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Sample records for finned tube performance

  1. Thermal performance analysis of a tube finned surface

    Energy Technology Data Exchange (ETDEWEB)

    Bilen, Kadir [Ataturk Univ., Dept. of Mechanical Engineering, Erzurum (Turkey); Akyol, Ugur [Trakya Univ., Dept. of Mechanical Engineering, Corlu/Tekirdag (Turkey); Yapici, Sinan [Ataturk Univ., Dept. of Chemical Engineering, Erzurum (Turkey)

    2002-07-01

    The present work submits an experimental work on the heat transfer and friction loss characteristic, employing a tube finned heating surface kept at a constant temperature in a rectangular channel. The tube fins attached on the surface (o.d.=29 mm) were arranged as either in-line or staggered. The parameters for the study were Reynolds number (3700-30 000), depending on hydraulic diameter, the distance between the tube fins in the flow direction (S{sub y}/D=1.72-3.45) and the fin arrangement. The change in the Nusselt number with these parameters was determined. For both tube fin arrangements, it was observed that increasing Reynolds number increased Nusselt number, and maximum heat transfer occurred at S{sub y}/D=2.59. Thermal performance for both arrangements were also determined and compared with respect to heat transfer from the same surface without fins. With staggered array, a heat transfer enhancement up to 25 per cent for S{sub y}/D=3.45 in staggered array was achieved in constant pumping power. (Author)

  2. Performance of residential air-conditioning systems with flow maldistribution in fin-and-tube evaporators

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Brix, Wiebke; Elmegaard, Brian; Larsen, Lars Finn Sloth

    2011-01-01

    Refrigerant and airflow maldistribution in fin-and-tube evaporators for residential air-conditioning was investigated with numerical modeling. Fin-and-tube heat exchangers usually have a pre-defined circuitry. However, the objective in this study was to perform a generic investigation of each individual maldistribution source in an independent manner. Therefore, the evaporator and the condenser were simplified to be straight tubes for the purposes of this study. The numerical model of the R410A ...

  3. Experimental and numerical investigation to evaluate the performance of triangular finned tube heat exchanger

    Directory of Open Access Journals (Sweden)

    Vinous M. Hameed, Bashar Muslem Essa

    2015-01-01

    Full Text Available Experimental and numerical investigation has been performed in this work to evaluate the performance for triangular finned tube heat exchanger. Experimental work included designing and manufacturing of shaped triangular fins from copper material of (10mm length, (10mm height, (1mm thickness, (22 mm distance between every two fins shaped and (15mm pitch between each two of fins which are install on the straight copper tube of (2m length having (20mm inner diameter and (22mm outer diameter. The inner tube is inserted inside the Perspex tube of (54mm inner diameter and (60mm outer diameter. Cold Air and hot water are used as working fluids in the shell side and tube side, respectively. Air at various mass flow rates (0.001875 to 0.003133 kg/sec flows through annuli and water at Reynold's numbers ranging from (10376.9 to 23348.03 flows through the inner tube. Performance of (smooth and finned tube heat exchanger was investigated experimentally. Experimental results showed that the enhancement of heat dissipation for triangular finned tube is (3.252 to4.502 times than that of smooth tube respectively. Numerical simulation has been carried out on present heat exchanger to analyze flow field and heat transfer using COMSOL computational fluid dynamic (CFD package model. The comparison between experimental work and numerical results showed good agreement.

  4. Study on turbulent flow and heat transfer performance of tubes with internal fins in EGR cooler

    Science.gov (United States)

    Liu, Lin; Ling, Xiang; Peng, Hao

    2015-01-01

    In this paper, flow and heat transfer performances of the tubes with internal longitudinal fins in Exhaust Gas Recirculation (EGR ) cooler were investigated by three-dimension computation and experiment . Each test tube was a single-pipe structure, without inner tube. Three-dimension computation was performed to determine the thermal characteristics difference between the two kinds of tubes, that is, the tube with an inner solid staff as a blocked structure and the tube without the blocked structure. The effects of fin width and fin height on heat transfer and flow are examined. For proving the validity of numerical method, the calculated results were compared with corresponding experimental data. The tube-side friction factor and heat transfer coefficient were examined. As a result, the maximum deviations between the numerical results and the experimental data are approximately 5.4 % for friction factor and 8.6 % for heat transfer coefficient, respectively. It is found that two types of internally finned tubes enhance significantly heat transfer. The heat transfer of the tube with blocked structure is better, while the pressure drop of the tube without blocked structure is lower. The comprehensive performance of the unblocked tube is better to applied in EGR cooler.

  5. Performance of residential air-conditioning systems with flow maldistribution in fin-and-tube evaporators

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Brix, Wiebke

    2011-01-01

    Refrigerant and airflow maldistribution in fin-and-tube evaporators for residential air-conditioning was investigated with numerical modeling. Fin-and-tube heat exchangers usually have a pre-defined circuitry. However, the objective in this study was to perform a generic investigation of each individual maldistribution source in an independent manner. Therefore, the evaporator and the condenser were simplified to be straight tubes for the purposes of this study. The numerical model of the R410A system, its verification and an investigation of individual maldistribution sources are presented in this paper. The maldistribution sources of interest were: inlet liquid/vapor phase distribution, feeder tube bending and airflow distribution. The results show that maldistribution reduced the cooling capacity and the coefficient of performance of the system. In particular, different phase distribution and non-uniform airflow distribution reduced the performance significantly. Different feeder tube bendings only caused a minor decrease in performance.

  6. Study on performance of plate fin - oval tube heat exchanger with vortex generators

    International Nuclear Information System (INIS)

    An experimental study was carried out to investigate the enhancement of heat transfer from the in-line and staggered arrays of oval tubes in the plate fin - tube heat exchanger with Delta - Wing type Vortex Generators(DWVG). Measurements of average heat(mass) - transfer coefficients on the tube surface were made using a naphthalene sublimation technique, and the flow losses were measured for Reynolds number ranging from 2000 to 3200. The influence of vortex generators parameters such as position and angle of attack was investigated. It was found that the heat transfer enhancement were increased by the existence of a vortex generators and flow losses were decreased by the oval tubes. The results indicate that performance of plate fin - tube heat exchanger can be improved simultanously by using vortex generators and oval tubes

  7. Study on performance of plate fin - oval tube heat exchanger with vortex generators

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hyeon Sik; Chun, Young Woo; Chung, In Kee [Yeungnam Univ., Gyeongsan (Korea, Republic of)

    2005-07-01

    An experimental study was carried out to investigate the enhancement of heat transfer from the in-line and staggered arrays of oval tubes in the plate fin - tube heat exchanger with Delta - Wing type Vortex Generators(DWVG). Measurements of average heat(mass) - transfer coefficients on the tube surface were made using a naphthalene sublimation technique, and the flow losses were measured for Reynolds number ranging from 2000 to 3200. The influence of vortex generators parameters such as position and angle of attack was investigated. It was found that the heat transfer enhancement were increased by the existence of a vortex generators and flow losses were decreased by the oval tubes. The results indicate that performance of plate fin - tube heat exchanger can be improved simultanously by using vortex generators and oval tubes.

  8. Thermal performance of a spirally coiled finned tube heat exchanger under wet-surface conditions

    International Nuclear Information System (INIS)

    This paper is a continuation of the author's previous work on spiral coil heat exchangers. In the present study, the heat transfer characteristics and the performance of a spirally coiled finned tube heat exchanger under wet-surface conditions are theoretically and experimentally investigated. The test section is a spiral-coil heat exchanger which consists of a steel shell and a spirally coiled tube unit. The spiral-coil unit consists of six layers of concentric spirally coiled finned tubes. Each tube is fabricated by bending a 9.6 mm diameter straight copper tube into a spiral-coil of four turns. The innermost and outermost diameters of each spiral-coil are 145.0 and 350.4 mm, respectively. Aluminium crimped spiral fins with thickness of 0.6 mm and outer diameter of 28.4 mm are placed around the tube. The edge of fin at the inner diameter is corrugated. Air and water are used as working fluids in shell side and tube side, respectively. The experiments are done under dehumidifying conditions. A mathematical model based on the conservation of mass and energy is developed to simulate the flow and heat transfer characteristics of working fluids flowing through the heat exchanger. The results obtained from the present model show reasonable agreement with the experimental data

  9. Experimental and numerical gas-side performance evaluation of finned-tube heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, Rene

    2009-07-01

    The objective of this work is to develop new heat transfer coefficient and pressure drop coefficient correlations for a heat exchanger with different numbers of consecutively arranged U-shaped finned-tubes in staggered layout, to characterize the global behavior at the gas-side (The overall heat transfer coefficients are averaged values across the entire fin surface of each tube (fin efficiency) as well as above all tubes within the bundle (average mean between inlet and outlet)). The experimental investigations at a semi-industrial scale test facility, at the Institute for Thermodynamics and Energy Conversion, were performed at different finned-tube bundle configurations. The tube bundles were arranged at equal transverse pitch, and in case of up to eight consecutively arranged tubes, with equal longitudinal pitch in staggered formation. Thus, a maximum total number of 88 tubes at different configurations was investigated. The Reynolds-Number was varied in the range between 4500 and 3500. The measurements were accomplished at the gas-side and at the water-side. The scope of a subsequently performed measurement validation should be addressed to fulfill the energy balance of the used system boundaries. The experimental setup, the measurement technique, and the measurement uncertainties are presented. As a result of measurements at different tube row configurations, a row correction factor for the heat transfer from the finned-tubes was derived. The average mean heat transfer seems to increase degressively from row to row. A comparison of the developed heat transfer and pressure drop correlations with available literature is presented. A three dimensional steady state numerical analysis of fluid flow and heat transfer across a tube row with a periodic array of solid and segmented fins was performed. For this reason, five different models of a single row finned-tube heat exchanger, with solid and segmented circular and helical I/U-shaped fins, were developed. The thermal field has been examined for convective transport phenomena. The effect of the parametrically varied Reynolds-number to the Nusselt-number was analyzed. Especially the difference between solid and serrated fins as well as the influence at the fin surface between two adjacent fins of I-shape and U-shape was analyzed. Apart from the application of a k-{epsilon} turbulence model, for modeling turbulence, a renormalization group theory (RNG) based on a k-{epsilon} turbulence model was applied to resolve near wall treatment between the adjacent fins. It is intended to verify the results of the CFC-calculations within the computational model boundaries with those calculated from the measurements at the test rig, to draw any conclusions from global to local effects of conjugated heat transfer and fluid flow. Therefore, at the gas-side of the test rig, a flow rectifier and an inflow channel should provide the same inlet conditions and the investigation of an array of finned-tubes represents the periodic boundaries as in the computational domain of the simulation. A comparison of the proposed equation for the Nusselt number with the simulation as well as most measurement results are found to be accurate with about {+-}15%; for the equation of the pressure drop coefficient an uncertainty of {+-}20% may be found. A performance evaluation criterion for single-phase flows was applied to characterize the effectivity of the various finned-tube bundles (solid/segmented I/U-shaped). The result of the comparison of heat transfer data from measurements, performed on a single U-segmented finned-tube row in cross-flow with a semi-tube installed at the channel wall, and the corresponding CFD calculations is found to be in excellent agreement, with only a small deviation. A qualitative and quantitative pressure drop coefficient comparison of the experiment at 8 tube rows (evaluated for a single tube row) with the CFD-calculation shows good agreement especially in the Re-range of about 6000 {<=} Re {<=} 20000. At higher Reynolds numbers than 20000 up to 50000, a diverging eff

  10. An experimental investigation on air-side performances of finned tube heat exchangers for indirect air-cooling tower

    Directory of Open Access Journals (Sweden)

    Du Xueping

    2014-01-01

    Full Text Available A tremendous quantity of water can be saved if the air cooling system is used, comparing with the ordinary water-cooling technology. In this study, two kinds of finned tube heat exchangers in an indirect air-cooling tower are experimentally studied, which are a plain finned oval-tube heat exchanger and a wavy-finned flat-tube heat exchanger in a cross flow of air. Four different air inlet angles (90°, 60 °, 45°, and 30° are tested separately to obtain the heat transfer and resistance performance. Then the air-side experimental correlations of the Nusselt number and friction factor are acquired. The comprehensive heat transfer performances for two finned tube heat exchangers under four air inlet angles are compared. For the plain finned oval-tube heat exchanger, the vertical angle (90° has the worst performance while 45° and 30° has the best performance at small ReDc and at large ReDc, respectively. For the wavy-finned flat-tube heat exchanger, the worst performance occurred at 60°, while the best performance occurred at 45° and 90° at small ReDc and at large ReDc, respectively. From the comparative results, it can be found that the air inlet angle has completely different effects on the comprehensive heat transfer performance for the heat exchangers with different structures.

  11. Effect of refrigerant mal-distribution in fin-and-tube evaporators on system performance

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian; Larsen, Lars Finn Sloth

    2009-01-01

    Refrigerant mal-distribution in fin-and-tube evaporators for residential air-conditioning (RAC) is investigated numerically in this paper. A model of the system is developed in the object-oriented modeling language Modelica. Themodels of the compressor and expansion valve are static, whereas the condenser is a dynamic moving boundary model. The evaporator model is a dynamic distributed one-dimensional homogeneous equilibrium model, in order to capture the distribution phenomena. Fin-and-tube hea...

  12. Experimental Performance of a Finned-tube Silica Gel Adsorption Chiller for Air-Conditioning Application

    Directory of Open Access Journals (Sweden)

    Mohammed A. Atiya

    2014-09-01

    Full Text Available This work presents the construction of a test apparatus for air-conditioning application that is flexible in changing a scaled down adsorbent bed modules. To improve the heat and mass transfer performance of the adsorbent bed, a finned-tube of the adsorbent bed heat exchanger was used. The results show that the specific cooling power (SCP and the coefficient of performance (COP are 163 W/kg and 0.16, respectively, when the cycle time is 40 min, the hot water temperature is 90oC, the cooling water temperature is 30oC and the evaporative water temperature is 11.4oC.

  13. Effect of fin thickness on the air-side performance of wavy fin-and-tube heat exchangers under dehumidifying conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kuvannarat, Thirapat; Wongwises, Somchai [Department of Mechanical Engineering, Fluid Mechanics, Thermal Engineering and Multiphase Flow Research Lab (FUTURE), King Mongkut' s University of Technology Thonburi, Bangmod, Bangkok 10140 (Thailand); Wang, Chi-Chuan [Energy and Resources Laboratory, Industrial Technology Research Institute, Hsinchu 310, Taiwan (China)

    2006-07-15

    This study investigated the effect of fin thickness on the air-side performance of wavy fin-and-tube heat exchangers under dehumidifying conditions. A total of 10 samples were tested with associated fin thickness ({delta}{sub f}) of 0.115mm and 0.25mm, respectively. For a heat exchanger with two rows (N=2) and fin pitch F{sub p} of 1.41mm, the effect of fin thickness on the heat transfer coefficient is more pronounced. The heat transfer coefficients for {delta}{sub f}=0.25mm is about 5-50% higher than those for {delta}{sub f}=0.115mm whereas the pressure drop for {delta}{sub f}=0.25mm is about 5-20% higher. The unexpected difference in heat transfer coefficient subject to fin thickness is attributable to better interactions between the directed main flow and the swirled flow caused by the condensate droplet for {delta}{sub f}=0.25mm. The maximum difference in heat transfer coefficients for N=2 and F{sub p}=2.54mm subject to the influence of fin thickness is reduced to about 20%, and there is no difference in heat transfer coefficient when the frontal velocity is above 3m/s. For N>=4 and F{sub p}=2.54mm, the influence of fin thickness on the heat transfer coefficients diminishes considerably. This is because of the presence of tube row, and the unsteady/vortex shedding feature at the down stream of wavy channel. Based on the present test results, a correlation is proposed to describe the air-side performance for wavy fin configurations, the mean deviations of the proposed heat transfer and friction correlations are 7.9% and 7.7%, respectively. (author)

  14. Three-dimensional performance analysis of plain fin tube heat exchangers in transitional regime

    International Nuclear Information System (INIS)

    Three-dimensional CFD simulations are carried out to investigate heat transfer and fluid flow characteristics of a four-row plain fin-and-tube heat exchanger using the Commercial Computational Fluid Dynamics Code ANSYS CFX 12.0. Heat transfer and pressure drop characteristics of the heat exchanger are investigated for Reynolds numbers ranging from 400 to 2000. Fluid flow and heat transfer are simulated and results compared using both laminar and turbulent flow models (k-?) with steady and incompressible fluid flow. Model validation is carried out by comparing the simulated case friction factor (f) and Colburn factor (j) with the experimental data of Wang et al.. Reasonable agreement is found between the simulations and experimental data. In this study the effect of geometrical parameters such as fin pitch, longitudinal pitch and transverse pitch of tube spacing are studied. Results are presented in the form of friction factor (f) and Colburn factor (j). For both laminar and transitional flow conditions heat transfer and friction factor decrease with the increase of longitudinal and transverse pitches of tube spacing whereas they increase with fin pitches for both in-line and staggered configurations. Efficiency index increases with the increase of longitudinal and transverse pitches of tube spacing but decreases with increase of fin pitches. For a particular Reynolds number, the efficiency index is higher in in-line arrangement than the staggered case. - Highlights: ? 3D CFD simulations for plain-fin-and-tube heat exchanger. ? Validated with experimental data. ? Parametric study for the effects of fluid flow and heat transfer.

  15. Effect of refrigerant mal-distribution in fin-and-tube evaporators on system performance

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian

    2009-01-01

    Refrigerant mal-distribution in fin-and-tube evaporators for residential air-conditioning (RAC) is investigated numerically in this paper. A model of the system is developed in the object-oriented modeling language Modelica. Themodels of the compressor and expansion valve are static, whereas the condenser is a dynamic moving boundary model. The evaporator model is a dynamic distributed one-dimensional homogeneous equilibrium model, in order to capture the distribution phenomena. Fin-and-tube heat exchangers usually have a complex circuitry, however the evaporator will be simplified to be two straight tubes. The refrigerant mal-distribution is then induced to the evaporator by varying the vapor quality at the inlet to each feeder tube, the pressure drop through each feeder tube and the air-flow across each tube. Finally it is shown that air-flow mal-distribution can be compensated by an intelligent distributor, that ensures equal superheat in both tubes. The refrigerant is R410a.

  16. Structure optimization and performance experiments of a solar-powered finned-tube adsorption refrigeration system

    International Nuclear Information System (INIS)

    Highlights: • New-structure finned-tube adsorption bed for enhancing heat and mass transfer. • Temperatures on different parts of the adsorption tubes differ little. • Maximum COP of 0.122 and maximum daily ice-making of 6.5 kg are achieved by experiments. • Cooling efficiency of system with valve control higher than that without valve control. - Abstract: A large-diameter aluminum-alloy finned-tube absorbent bed collector was designed and optimized by enhancing the heat and mass transfer in the collector. The collection efficiency of the adsorbent bed collector was between 31.64% and 42.7%, and the temperature distribution in the absorbent bed was relatively uniform, beneficial to adsorption/desorption of the adsorbate in the absorbent bed. A solar-powered solid adsorption refrigeration system with the finned-tube absorbent bed collector was built. Some experiments corresponding to the adsorption/desorption process with and without a valve control were conducted in four typical weather conditions: sunny with clear sky, sunny with partly cloudy sky, cloudy sky and overcast sky. Activated carbon–methanol was utilized as the working pair for adsorption refrigeration in the experiments. The experiments achieved the maximum COP of 0.122 and the maximum daily ice-making of 6.5 kg. Under the weather conditions of sunny with clear sky, sunny with partly cloudy sky, and cloudy sky, ice-making phenomenon were observed. Even in the overcast-sky weather condition, the cooling efficiency of the system still reached 0.039 when the total solar radiation was 11.51 MJ. The cooling efficiency of the solar-powered adsorption refrigeration system with a valve control in the adsorption/desorption process was significantly higher than that without a valve control

  17. Numerical Study on Heat Transfer Performance of Crossflow Fin-tube Heat Exchanger Depending on Different Fan Positions

    International Nuclear Information System (INIS)

    The convective heat transfer of a crossflow fin-tube heat exchanger was studied numerically. In order to investigate the dependence of the heat transfer performance on the fan position, several cases with different blowing and suction types were selected for the fan position. A staggered tube arrangement was used for the heat exchanger, and the temperatures of the tube wall and air were 50 .deg. C and 30 .deg. C, respectively. The three-dimensional flow structures were examined based on the results. In addition, the convective heat transfer coefficient and mean temperature difference between the inlet and outlet of the heat exchanger were analyzed for the various fan positions, and the heat transfer performance was investigated.

  18. Experimental performance evaluation of multi-row, plate finned-tube, direct expansion air cooling and dehumidifying coils

    Energy Technology Data Exchange (ETDEWEB)

    Turaga, M.

    1989-03-01

    Experimental studies were conducted on plate finned-tube, direct expansion (DX) air cooling and dehumidifying heat exchangers to determine the effects of significant coil geometric parameters and the fluid flow parameters on the coil performance. Tests were conducted on 10 coils with varied fin densities (3.1-5.5 fins/cm) and tube rows (3-8) under both dry and wet surface conditions for the air-side. Correlations for the average heat transfer and pressure drop factors for the working fluids (air and refrigerant) are developed from the experimental data. Regression analysis is used to determine the influential coil geometric parameters on the heat exchanger performance. In the range of air flow Reynolds number considered (300-1500), the air-side average heat transfer and pressure drop factors were found to be independent of the number of tube rows and decrease when the fin density increases (for a given Reynolds number). The refrigerant-side average Nusselt number was found to be an increasing linear function of the two phase heat transfer parameter, and the corresponding pressure drop factor was found to be a decreasing linear function of the two phase pressure drop parameter. The presence of oil (ca 2 wt %) was found to increase the average Nusselt number by 30-40% and the average pressure drop factor by 25% compared to oil-free flow. A method for selection of DX coils is developed from the correlations which may be used to estimate the part-load performance of DX coils. 58 refs., 59 figs., 15 tabs.

  19. Experimental performance evaluation of multi-row, plate finned-tube, direct expansion air cooling and dehumidifying coils

    Energy Technology Data Exchange (ETDEWEB)

    Turaga, M.

    1989-01-01

    Experimental studies are conducted on Plate finned-tube, Direct expansion (DX), air cooling and dehumidifying heat exchangers to determine the effects of significant coil geometric parameters and the fluid flow parameters on the coil performance. Tests are conducted on ten (10) coils with varied fin densities (3.1 to 5.5 fins/cm) and tube rows (3 to 8) under both dry and wet surface conditions for the air-side. Such studies, on the performance of DX-coils for comfort air conditioning applications, are very limited in the open literature. Correlations for the average heat transfer and pressure drop factors for the working fluids (air and refrigerant) are developed from the experimental data; such correlations for refrigerant in DX-coils are very limited in the present literature. Regression analysis is used to determine the influential coil geometric parameters on the heat exchanger performance. In the range of the air flow Reynolds number considered (300 < Re{sub a} < 1,500), the air-side average heat transfer and pressure drop factors (for both dry and wet surface conditions) are found to be independent of the number of tube rows and decrease when the fin density increases (for a given Reynolds number). The refrigerant-side average Nusselt number (Nu{sub r}) is found to be an increasing linear function of the two-phase heat transfer parameter (Re{sub r,l}{sup 2} K{sub f}) and the corresponding pressure drop factor (f{sub r}) is found to be decreasing linear function of the two-phase pressure drop parameter (Re{sub r,l}/K{sub f}). The presence of oil (about 2% by weight), is found to increase both the average Nusselt number (by 30 to 40%) and the average pressure drop factor (by 25%), compared to the corresponding oil free flow. A method for selection of DX-coils is developed from the correlations for prediction of the average heat transfer and pressure drop factors.

  20. CFD Analysis of Plate Fin Tube Heat Exchanger for Various Fin Inclinations

    OpenAIRE

    Subodh Bahirat,; P. V. Joshi

    2014-01-01

    ANSYS Fluent software is used for three dimensional CFD simulations to investigate heat transfer and fluid flow characteristics of six different fin angles with plain fin tube heat exchangers. The numerical simulation of the fin tube heat exchanger was performed by using a three dimensional numerical computation technique. Geometry of model is created and meshed by using ANSYS Workbench software. To solve the equation for the fluid flow and heat transfer analysis ANSYS FLUENT ...

  1. Performance study of silica gel coated fin-tube heat exchanger cooling system based on a developed mathematical model

    International Nuclear Information System (INIS)

    Research highlights: ? A dynamic mathematical model is built to predict the performance of DCHE system. ? Operation time in dehumidification is a crucial parameter to system performance. ? Under ARI summer condition, the largest cooling power can reach to 2.6 kW. ? Under ARI humid condition, the largest cooling power can reach to 3.4 kW. ? System performs better with smaller fin distance and tube diameter. -- Abstract: Desiccant coated heat exchanger (DCHE) system can handle latent and sensible load simultaneously by removing the released adsorption heat in dehumidification process. The system can also be driven by low grade thermal energy such as solar energy. In this paper, a dynamic one-dimensional mathematical model validated by experimental data is established to predict the performance of DCHE system, using conventional silica gel as desiccant material. Cooling performance of DCHE system is calculated under ARI (American Air-conditioning and Refrigeration Institute) summer and humid conditions. Simulated results show that the operation time in dehumidification process is a crucial factor for cooling capacity of DCHE system, which can be enhanced by eliminating the initial period with higher outlet air temperature, the largest cooling power of DCHE system increase from 2.6 kW to 3.5 kW by eliminating first 50 s of operation time under ARI summer condition. The results also prove that the system can provide cooling power to indoor condition with selective operation time when regeneration temperature varies from 50 oC to 80 oC. Besides, the model is adopted to analyze the effects of some structural parameters on system performance under simulated condition. The system performs well in smaller cobber tube external diameter condition, while both transient heat and mass transfer capacity can be enhanced under the condition of smaller distance between the fins.

  2. PHASE CHANGE AROUND A FINNED TUBE

    Directory of Open Access Journals (Sweden)

    Aytunç EREK

    2003-01-01

    Full Text Available This study presents the heat transfer enhancement in the thermal energy storage system by using radially finned tube. The solution of the system consists of the solving the equations of the heat transfer fluid (HTF, the pipe wall and fin, and the phase change material (PCM as one domain. The control volume finite difference approach and the semi implicit solver (SIS are used to solve the equations. Fully developed velocity distribution is taken in the HTF. Flow parameters (Re number and inlet temperature of coolant and fin parameters (the number of fins, fin length, fin thickness are found to influence solidification fronts and the total stored energy.

  3. Enhance heat transfer for PCM melting in triplex tube with internal–external fins

    International Nuclear Information System (INIS)

    Highlights: • Three heating methods were applied to melt the PCM in TTHX without fin. • Heat transfer enhanced by using fin to inner, middle tubes, and both tubes. • Performances of TTHX with fin were compared with finned, internally finned tube. - Abstract: Thermal energy storage is critical for eliminating the discrepancy between energy supply and demand as well as for improving the efficiency of solar energy systems. This study numerically investigates the melting process in a triplex-tube heat exchanger with phase-change material (PCM) RT82. A two-dimensional numerical model is developed using the Fluent 6.3.26 software program. Three heating methods were used to melt the PCM from the inside tube, outside tube, and both tubes. Internal, external, and internal–external fin enhancement techniques were studied to improve the heat transfer between the PCM and heat transfer fluid. Enhancement techniques were compared with the inside tube heating, outside tube heating, both tube heating as well as the finned and internally finned tube. The effects of fin length on the enhancement techniques were investigated. Using a triplex-tube heat exchanger with internal–external fins, predicted results indicated that melting time is reduced to 43.3% in the triplex tube without fins. Experiments were conducted to validate the proposed model. Simulated results correspond with the experimental results

  4. CFD Analysis of Plate Fin Tube Heat Exchanger for Various Fin Inclinations

    Directory of Open Access Journals (Sweden)

    Subodh Bahirat,

    2014-08-01

    Full Text Available ANSYS Fluent software is used for three dimensional CFD simulations to investigate heat transfer and fluid flow characteristics of six different fin angles with plain fin tube heat exchangers. The numerical simulation of the fin tube heat exchanger was performed by using a three dimensional numerical computation technique. Geometry of model is created and meshed by using ANSYS Workbench software. To solve the equation for the fluid flow and heat transfer analysis ANSYS FLUENT was used in the fin-tube heat exchanger. The fluid flow and heat transfer are simulated and result compared for both laminar and turbulent flow models k-epsilon and SST k-omega, with steady state solvers to calculate heat transfer, flow velocity and temperature fields of variable inclined fin angles (? = 00 ,100 , 200 , 300 , 400 ,500 . Model is validate by comparing the simulated value of velocity, temperature and colburn factor with experimental and numerical results investigated by WANG [1] and GHORI KIRAR [10]. Reasonable agreement is found between the simulations and other results, and the ANSYS Fluent software is sufficient for simulating the flow fields in tube fin heat exchanger.

  5. Air side flow analysis of fin-tube heat exchanger with vortex generator

    International Nuclear Information System (INIS)

    Fin-tube heat exchangers are widely used in refrigeration systems. To improve the performance of fin-tube heat exchangers, the shape of plain fin was developed in slit fin and louver fin. These pins have higher heat transfer performance as well as larger pressure drop. Recent studies of a Delta Winglet Vortex Generator (DWVG) show less heat transfer capacity than louver fin. However, the DWVG has very small pressure drop. This paper compares the performance for the plain fin and DWVG fin in terms of flow characteristics and heat transfer based on CFD analyses. The DWVG generates vortex and delayed flow separation and leads to a reduction of a wake region behind a tube. The results show that the DWVG produces improved heat transfer and reduced pressure drop compared to a plain fin. This result is opposite to the Reynolds analogy.

  6. Shape optimization of a heat exchanger with internally finned tube

    International Nuclear Information System (INIS)

    Optimization of a heat exchanger with internally finned circular tubes has been performed for three-dimensional periodically fully developed turbulent flow and heat transfer. The design variables of fin number N, fin width (d1,d2) and fin height(H) , are numerically optimized for the limiting conditions of N = 22?37, d1= 0.5?1.5 mm, d2 0.5?1.5 mm, H = 0.1?1.5. Due to the periodic boundary conditions along main flow direction, the three layers of meshes are considered. The CFD and the mathematical optimization are coupled to optimize the heat exchanger. The flow and thermal fields are predicted using the finite volume method and the optimization is carried out by using the Sequential Quadratic Programming (SQP) method which is widely used in the constrained nonlinear optimization problem

  7. Heat transfer, erosion and acid condensation characteristics for novel H-type finned oval tube

    Science.gov (United States)

    Wang, Y.; Zhao, X.; Tang, G.

    2015-09-01

    Low efficiency of heat transfer, acid corrosion and erosion of economizers affect the economy and security in coal-fired power plants significantly. The H-type finned oval tube is proposed to alleviate these problems. Based on the H-type finned oval tube, we investigated three novel types of fins, including bleeding dimples, longitudinal vortex generators (LVGs), and compound dimple-LVG. We considered the three aspects together, and obtained the heat transfer, acid condensation rate and erosion loss. The results show that the tube bank with the new structured fins can improve the performance on the three aspects, and the compound dimple-LVG performs the highest comprehensive effect.

  8. Investigations into the dynamic behaviour of finned tube heat exchangers

    International Nuclear Information System (INIS)

    Atmospheric disturbances due to thunder storms, side wind effects on the shell or ground inversion can impair the heat dissipation of a cooling tower. These effects react on the overall power plant, which is reflected in the varied electrical output. This uncontrolled behaviour has been investigated in detail for the case of a boiling water reactor nuclear power station with indirect natural draught dry cooling and compared with controlled performance. A computer model, which has been checked out by means of experimental investigations on three different types of tube, is presented to describe the dynamic behaviour of finned tube heat exchangers. (orig.)

  9. Pressure loss and heat transfer studies performed on axial-flow finned-tube bundle heat exchangers

    International Nuclear Information System (INIS)

    The experimental studies intend to determine the dependence on the parameters of influence state of flow, tube length, and bundle pitch of the heat transfer and pressure loss characteristic of two tube types in the bundle. By means of suitable parameters for heat flow and pressure loss a comparison will be made of the heat transfer and pressure loss power of the axial-flow furried-tube bundle systems investigated here and conventional heat exchangers. (orig.)

  10. Development of auto balancing fin tube ECT instrument

    International Nuclear Information System (INIS)

    Eddy Current Testing (ECT) instrument for copper fin tube was developed in this research. The instrument was composed of signal generator, signal detector, phase detector, phase controller, digital signal processor and PC software. And this on-line instrument was installed at LG for fin copper tube inspection which enabled small defects to detect and reported for evaluation.

  11. Heat exchanger with several parallel tubes with fins attached

    International Nuclear Information System (INIS)

    The tubes of the heat exchanger convey a first fluid. They are provided with ripple shaped sheet metal fins, which are distributed over the tubes length. A second fluid flows in the remaining spaces between the fins. The corrugations on each fin are only on the outer part of which immediately surrounds the corresponding tube and extend towards the neighbouring tube in the same row. The corrugations are free from perforations. The pressure loss of the second fluid is thereby significantly reduced and maintains good heat transfer properties. 7 figs

  12. Compensation of flow maldistribution in fin-and-tube evaporators for residential air-conditioning

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Brix, Wiebke; Elmegaard, Brian; Larsen, Lars Finn Sloth

    2011-01-01

    Compensation of flow maldistribution in multi-channel fin-and-tube evaporators for residential air-conditioning is investigated by numerical modeling. The considered sources of maldistribution are distribution of the liquid and vapor phases in the distributor and non-uniform airflow distribution. Fin-and-tube heat exchangers usually have a predefined circuitry, however, the evaporator model is simplified to have straight tubes, in order to perform a generic investigation. The compensation of flo...

  13. Laminar forced convection inside externally finned tubes

    International Nuclear Information System (INIS)

    Analytical solutions are obtained for thermal entry region problems inside ducts with axially varying heat transFer coefficient, by making use of the ideas in the recently advanced generalized integral transform technique. The analysis is applied to stepwise variations of Biot number that simulate intermitent rows of external fins. Numerical results are obtained for different fin arrangements, in a systematic manner, so as to critically examine the relative marits of wider and/or more numerous fin rows. (author)

  14. Performance analysis of a small regenerative gas turbine system adopting steam injection and side-wall in finned tube evaporator

    International Nuclear Information System (INIS)

    Small gas turbines in power range of several MWs are quite suitable for application in distributed generation as well as Community Energy Systems (CES). Humidification is an effective way to improve gas turbine performance, and steam injection is the most general and practically feasible method. This study intended to examine the effect of steam injection on the performance of several MW class gas turbines. A primary concern is given to the regenerative cycle gas turbine. The steam injection effect on the performance of a system without the regenerator (i.e. a simple cycle) is also examined. In addition, the influence of bypass of some of the exhaust gas on the performance of the gas turbine, especially the regenerative cycle gas turbine, is evaluated.

  15. 3D analysis of thermal exchange in finned batteries. A comparison between round and elliptical tubes

    International Nuclear Information System (INIS)

    In this paper a numerical 3D analysis of the thermal exchange in air-cooled finned batteries has been carried out. Speed and temperature values in each hub of the numerical simulation domain have been reckoned both at different air flows and with different shapes of the tubes. The thermal power exchanged between tubes and air is obtained by the simulation of a numerical model of a finned battery with round section tubes and is compared to the values obtained for three batteries with elliptical section tubes. The comparison has been performed for different values of the air input speed

  16. Experimental Research on heat transfer enhancement of lubricating-oil cooler with mixing integral pin-fin tubes and plain tubes

    International Nuclear Information System (INIS)

    A lot of comparison experimental research has been done to the lubricating-oil cooler with mixing integral pin-fin tubes and plain tubes. It is discovered that the mixing integral pin-fin tubes heat transfer capacity in unit volume is higher, pressure drop is lower, and the very strong heat transfer ability than plain tubes when oil volume flow rate is at constant value. The results show the performance of lubricating-oil cooler with mixing integral pin-fin tubes and plain tubes is superiority. So this can made lubricating-oil cooler miniaturize in the same Heat changing condition. (authors)

  17. Effective Heat Transfer Enhancement in Finned Tube Heat Exchanger with Different Fin Profiles

    Directory of Open Access Journals (Sweden)

    J.A.Livingston1 , P. Selvakumar2

    2013-04-01

    Full Text Available During cross flow in a heat exchanger, heat transfer in the front portion of the tube is more compared to back portion of the tube. This is due to less formation of vortices at the backside of the tube. For uniform heat transfer to take place throughout the tube, it is necessary to increase the vortex formation at the rear side of the tube. The aim of this study is to explore the possibilities of improving the flow structure and thereby increasing uniform heat transfer around the tubes by introducing special type of fin arrangement over the tubes. The effect of shape and orientation of the fin on vortex generation and respective heat transfers are studied numerically. It have been identified that by introducing special type of fin arrangement over the tube there is a possibility for increase the vortex formation at the rear portion of the tube, which significantly leads to creation of uniform heat transfer all around the tube.

  18. Fast breeder cladding tubes provided with helical fins

    International Nuclear Information System (INIS)

    Development of fast breeder tubes with helical fins started around 1966. The development was initiated mainly by the search for a more favorable alternative to the conventional spacers such as grids and spiral wires. First of all the possibility was investigated of fabricating them on an industrial scale. The first thermohydraulic and fluiddynamic tests were made in parallel by AEG, GfK and Interatom. Besides the possibility of industrial fabrication the problems of non-destructive testing for geometry and material defects had to be treated with priority. In this report the different stages of development are shown and, finally, two rather large projects are described. These projects are the study ready for the licensing procedure concerning the irradiation of finned tube oxide fuel elements in KNK II and the already completed 19-rod fuel element bundle irradiation experiment Mol 7D of GfK performed in the 500 kW sodium loop of the Belgian BR2 reactor. In this BR2 experiment the maximum target burnup of 85,000 MWd/t of oxide was attained without trouble. (orig.)

  19. CFD analysis of tube-fin 'no-frost' evaporators

    Scientific Electronic Library Online (English)

    Jader R, Barbosa, Jr; Christian J. L, Hermes; Cláudio, Melo.

    2010-12-01

    Full Text Available The purpose of this paper is to assess some aspects of the design of evaporators for household refrigeration appliances using Computational Fluid Dynamics (CFD). The evaporators under study are tube-fin 'no-frost' heat exchangers with forced convection on the air-side and a staggered tube configurat [...] ion. The calculation methodology was verified against experimental data for the heat transfer rate, thermal conductance and pressure drop obtained for two evaporators with different geometries. The average errors of the heat transfer rate, thermal conductance and pressure drop were 10%, 3% and 11%, respectively. The CFD model was then used to assess the influence of geometric parameters such as the presence and position of the electrical heater coil relative to the tubes, the fin configuration and the width of the by-pass clearance between the outer edge of the fins and the tube bank for conditions typical of the design of household refrigeration appliances

  20. Experimental study of heat transfer and pressure drop characteristics on shell-side of pin-fin tube oil cooler

    International Nuclear Information System (INIS)

    The comparative experimental study for one smooth tube oil cooler and three pin-fin tube oil coolers was performed by using lubricating oil as heat transfer medium. The experimental results indicate that in the range of experimental study, total heat transfer coefficient of pin-fin tube oil coolers is about 1.4-2 times higher than that of the smooth tube oil cooler. The heat transfer and pressure drop characteristics are greatly different for different structures of pin-fin tube oil coolers. The effects of the structure of pin-fin tube and shell-side flow path number are dominant to influence heat transfer and pressure drop characteristics of oil coolers. In the range of experimental study, large pin-fin height is conducive to the oil flow disturbance, but not conducive to the heat transfer on the tube-base heat transfer surface of pin-fin tube; single-pass pin-fin tube oil cooler offers high total heat transfer coefficient and volumetric heat transfer capacity, the global heat transfer performance and the friction characteristics are better than that of two-pass pin-fin tube oil cooler. (authors)

  1. Finned double-tube PCM system as a waste heat storage

    Science.gov (United States)

    Alhamdo, M. H.; Theeb, M. A.; Golam, A. S.

    2015-11-01

    In this work, focus is taken on developing a waste heat recovery system for capturing potential of exhaust heat from an air conditioner unit to be reused later. This system has the ability to store heat in phase change material (PCM) and then release it to a discharge water system when required. To achieve this goal, a system of Finned, Water-PCM, Double tube (FWD) has been developed and tested. Different profiles of fins attached to the (FWD) system have been investigated for increasing the thermal conductivity of the PCM. These include using Circular Finned, Water-PCM, Double tube (CFWD) system; Longitudinal Finned, Water-PCM, Double tube (LFWD) system; Spiral Finned, Water-PCM, Double tube (SFWD) system; as well as; Without Fins, Water-PCM, Double tube (WFWD) system. An experimental test rig that attached to an air-conditioner unit has been built to include 32- tubes of the FWD systems for both vertical and horizontal layouts during charging and water discharging processes. Results show a significant performance improvement when using spiral and circular fins during charging process at vertical position. However, longitudinal and without fins showed better performance in horizontal position. Overall, the developed SFWD system in vertical position has been found to exhibit the most effective type due to the fastest PCM melting and solidification. As compared to the WFWD system, the FWD systems have been found to increase the PCM temperature gain of about 15.3% for SFWD system; 8.2% for CFWD; and 4.3% for LFWD system.

  2. Experimental investigation of water sprayed finned heat exchanger tube bundles

    International Nuclear Information System (INIS)

    Experimental investigations have been made to study the performance of two finned tube-bundle heat exchangers (FORGO type) when wetted by water sprays. The heat exchangers are designed to cool water in a dry cooling tower. The test-elements had a frontal area of 1 m2. The water sprays were created by 20 nozzles, 200 mm in front of the heat exchangers. Air velocities at the inlet of the coolers were in the range 0,8 m/s to 12 m/s and initial temperature differences ITD reached 45 degrees C. The test facility was designed to determine the combined latent and sensible heat fluxes in the wetted heat exchanger, the airside pressure drop and the air humidity and temperature at the exchanger inlet and outlet, and to measure the weight of the water wetting the cooler's surface. The sprayed test elements were investigated in different positions, but most of the experiments were carried out in the position with the fins horizontal

  3. Transfer coefficients in elliptical tubes and plate fin heat exchangers

    International Nuclear Information System (INIS)

    Mean transfer coefficients in elliptical tubes and plate fin heat exchangers were determined by application of heat and mass transfer analogy in conjunction with the naphthalene sublimation technique. The transfer coefficients are presented in a dimensionless form as functions of the Reynolds number. By using the least squares method analytical expressions for the transfer coefficients were determined with low scattering. (E.G.)

  4. Experimental studies on pressure drop characteristics of cryogenic cross-counter flow coiled finned tube heat exchangers

    Science.gov (United States)

    Gupta, Prabhat Kumar; Kush, P. K.; Tiwari, Ashesh

    2010-04-01

    Cross-counter flow coiled finned tube heat exchangers used in medium capacity helium liquefiers/refrigerators were developed in our lab. These heat exchangers were developed using integrated low finned tubes. Experimental studies have been performed to know the pressure drop characteristics of tube side and shell side flow of these heat exchangers. All experiments were performed at room temperature in the Reynolds number range of 3000-30,000 for tube side and 25-155 for shell side. The results of present experiments indicate that available correlations for tube side can not be used for prediction of tube side pressure drop data due to complex surface formation at inner side of tube during formation of fins over the outer surface. Results also indicate that surface roughness effect becomes more pronounced as the value of di/ D m increases. New correlations based on present experimental data are proposed for predicting the friction factors for tube side and shell side.

  5. CFD analysis of fin tube heat exchanger with a pair of delta winglet vortex generators

    International Nuclear Information System (INIS)

    Among tubular heat exchangers, fin tube types are the most widely used in refrigeration and air-conditioning equipment. Efforts to enhance the performance of these heat exchangers included variations in the fin shape from a plain fin to a slit and louver type. In the context of heat transfer augmentation, the performance of vortex generators has also been investigated. Delta winglet vortex generators have recently attracted research interest, partly due to experimental data showing that their addition to fin-tube heat exchangers considerably reduces pressure loss at heat transfer capacity of nearly the same level. The efficiency of the delta winglet vortex generators widely varies depending on their size and shape, as well as the locations where they are implemented. In this paper, the flow field around delta winglet vortex generators in a common flow up arrangement was analyzed in terms of flow characteristics and heat transfer using computational fluid dynamics methods. Flow mixing due to vortices and delayed separation due to acceleration influence the overall fin performance. The fin with delta winglet vortex generators exhibited a pressure loss lower than that of a plain fin, and the heat transfer performance was enhanced at high air velocity or Reynolds number

  6. The optimization of fin-tube heat exchanger with longitudinal vortex generators using response surface approximation and genetic algorithm

    Science.gov (United States)

    Wu, Xuehong; Liu, DanDan; Zhao, Min; Lu, YanLi; Song, Xiaoyong

    2015-11-01

    Delta winglet works better than other vortex generators in improving the performance of fin-tube heat exchangers. In this paper, Response Surface Approximation is used to study the effects of the fin pitch, the ratio of the longitudinal tube pitch to transverse tube pitch, the ratio of both sides V 1 , V h of delta winglets and the attack angle of delta winglets on the performance of fin-tube heat exchanger. Firstly, Twenty-nine numerical group experiments including five times repeated experiments at the central point are conducted. Then, the analyses of variable (ANOVA) and regression are performed to verify the accuracy of the polynomial coefficients. Finally, the optimization of the fin-tube heat exchanger using the Genetic Algorithm is conducted and the best performance of j/f (1/3) is found to be 0.07945, which is consistent with the numerical result.

  7. Fouling of HVAC fin and tube heat exchangers

    International Nuclear Information System (INIS)

    Fin and tube heat exchangers are used widely in residential, commercial and industrial HVAC applications. Invariably, indoor and outdoor air contaminants foul these heat exchangers. This fouling can cause decreased capacity and efficiency of the HVAC equipment as well as indoor air quality problems related to microbiological growth. This paper describes laboratory studies to investigate the mechanisms that cause fouling. The laboratory experiments involve subjecting a 4.7 fins/cm (12 fins/inch) fin and tube heat exchanger to an air stream that contains monodisperse particles. Air velocities ranging from 1.5-5.2 m/s (295 ft/min-1024 ft/min) and particle sizes from 1-8.6(micro)m are used. The measured fraction of particles that deposit as well as information about the location of the deposited material indicate that particles greater than about 1(micro)m contribute to fouling. These experimental results are used to validate a scaling analysis that describes the relative importance of several deposition mechanisms including impaction, Brownian diffusion, turbophoresis, thermophoresis, diffusiophoresis, and gravitational settling. The analysis is extended to apply to different fin spacings and particle sizes typical of those found in indoor air

  8. Experimental Investigation of Heat Transfer and Pressure Drop Characteristics of H-type Finned Tube Banks

    OpenAIRE

    Heng Chen; Yungang Wang; Qinxin Zhao; Haidong Ma; Yuxin Li; Zhongya Chen

    2014-01-01

    H-type finned tube heat exchanger elements maintain a high capacity for heat transfer, possess superior self-cleaning properties and retain the ability to effect flue gas waste heat recovery in boiler renovations. In this paper, the heat transfer and pressure drop characteristics of H-type finned tube banks are studied via an experimental open high-temperature wind tunnel system. The effects of fin width, fin height, fin pitch and air velocity on fin efficiency, convective heat transfer coe...

  9. Compensation of airflow maldistribution in fin-and-tube evaporators

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Tiedemann, Thomas

    2012-01-01

    Compensation of airflow maldistribution in fin-and tube evaporators for residential air-conditioning is investigated with regards to circuitry design and control of individual channel superheats. In particularly, the interlaced and the face split circuitry designs are compared numerically using a linear velocity profile and a CFD predicted velocity profile obtained from Kærn (2011d) in dry and wet conditions. The circuitry models are validated experimentally in wet conditions, and for this purpose a test case interlaced evaporator (17.58 kW) was reconstructed in order to become a face split evaporator by modifying its U-bend connections. Furthermore, a 14% and 28% blockage of the face split evaporator is studied experimentally with control of individual channel superheats. It is shown that the face split circuitry with compensation gives the best performance in both dry and wet conditions, however with lower gains in wet conditions (around 3% in cooling capacity and 7-9% in UA-value). This performance gain incooling capacity is below the uncertainty in standard experiments, however the gain may be revealed and/or validated by the possible area savings experimentally, i.e. in terms of overall UA-value.

  10. Numerical Analysis of Tube-Fin Heat Exchanger using Fluent

    Directory of Open Access Journals (Sweden)

    M. V. Ghori

    2012-08-01

    Full Text Available Three-dimensional CFD simulations are carried out to investigate heat transfer and fluid flow characteristics of two-row plain Tube and Fin heat exchanger using FLUENT software. Heat transfer and pressure drop characteristics of the heat exchanger are investigated for Reynolds numbers ranging from 330 to 7000. Model geometry is created and meshed by using GAMBIT software. Fluid flow and heat transfer are simulated and results compared using both laminar and turbulent flow models k-, and SST k-omega, with steady-state solvers to calculate pressure drop, flow, and temperature fields. Model validation is carried out by comparing the simulated value friction factor f and Colburn factor j to experimental results investigate by Wang. Reasonable agreement is found between the simulations and experimental data, and the fluent software has been sufficient for simulating the flow fields in tube-fin heat exchangers.

  11. Numerical Analysis of Tube-Fin Heat Exchanger using Fluent

    OpenAIRE

    M. V. Ghori; R. K. Kirar

    2012-01-01

    Three-dimensional CFD simulations are carried out to investigate heat transfer and fluid flow characteristics of two-row plain Tube and Fin heat exchanger using FLUENT software. Heat transfer and pressure drop characteristics of the heat exchanger are investigated for Reynolds numbers ranging from 330 to 7000. Model geometry is created and meshed by using GAMBIT software. Fluid flow and heat transfer are simulated and results compared using both laminar and turbulent flow models k-, and SST k...

  12. Compensation of airflow maldistribution in fin-and-tube evaporators

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Tiedemann, Thomas

    2012-01-01

    Compensation of airflow maldistribution in fin-and tube evaporators for residential air-conditioning is investigated with regards to circuitry design and control of individual channel superheats. In particularly, the interlaced and the face split circuitry designs are compared numerically using a linear velocity profile and a CFD predicted velocity profile obtained from Kærn (2011d) in dry and wet conditions. The circuitry models are validated experimentally in wet conditions, and for this purpo...

  13. Mixed convection laminar flow and heat transfer of liquids in horizontal internally finned tubes

    Energy Technology Data Exchange (ETDEWEB)

    Shome, B. [Univ. of Delaware, Newark, DE (United States). Dept. of Mechanical Engineering

    1998-01-01

    Energy and material savings, as well as economic incentives, have led to concentrated efforts over the past several decades in the field of heat transfer enhancement to produce more efficient and compact heat exchangers. Internally finned tubes are widely used for heat transfer enhancement, particularly in chemical process and petroleum industries. A finned tube heat exchanger with optimum geometry could offer 35--40% increase in heat duty for equal pumping power and size over a smooth tube heat exchanger or a comparable decrease in the heat exchanger size for a given heat duty. Developing mixed convection flow in internally finned tubes with variable viscosity was numerically investigated for a fin geometry range of 8 {le} N {le} 24, 0.1 {le} H {le} 0.3 and an operating condition range of 50 {le} Pr{sub in} {le} 1,250, 0 {le} Ra{sub in} {le} 10{sup 7}, and 0 {le} q{sub w}d/k{sub in} {le} 2,000. The numerical model was validated by comparison with existing numerical and experimental data. Internal finning was found to produce a complex two-cell, buoyancy-induced vortex structure. The results show that coring (retarded velocity in the interfin region) leads to poor heat transfer performance of tubes with large numbers of fins or with tall fins. The overall results indicated that large enhancement in the heat transfer can be obtained in the entrance region. Furthermore, variable viscosity effects are seen to have a pronounced effect on the friction factor and Nusselt number predictions.

  14. Analysis of flow maldistribution in fin-and-tube evaporators for residential air-conditioning systems

    OpenAIRE

    Kærn, Martin Ryhl

    2011-01-01

    This thesis is concerned with the effects of flow maldistribution in fin-and-tube A-coil evaporators for residential air-conditioning and compensation potentials with regards to system performance. The goal is to create a better understanding of flow maldistribution and the involved physical phenomenons. Moreover, the study investigates the individual and combined effects of non-uniform inlet liquid/vapor distribution, different feeder tube bending and non-uniform airflow. I...

  15. Analysis of flow maldistribution in fin-and-tube evaporators for residential air-conditioning systems

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl

    2011-01-01

    This thesis is concerned with the effects of flow maldistribution in fin-and-tube A-coil evaporators for residential air-conditioning and compensation potentials with regards to system performance. The goal is to create a better understanding of flow maldistribution and the involved physical phenomenons. Moreover, the study investigates the individual and combined effects of non-uniform inlet liquid/vapor distribution, different feeder tube bending and non-uniform airflow. In addition, the possi...

  16. Compensation of flow maldistribution in fin-and-tube evaporators for residential air-conditioning

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Brix, Wiebke

    2011-01-01

    Compensation of flow maldistribution in multi-channel fin-and-tube evaporators for residential air-conditioning is investigated by numerical modeling. The considered sources of maldistribution are distribution of the liquid and vapor phases in the distributor and non-uniform airflow distribution. Fin-and-tube heat exchangers usually have a predefined circuitry, however, the evaporator model is simplified to have straight tubes, in order to perform a generic investigation. The compensation of flow maldistribution is performed by control of the superheat in the individual channels. Furthermore, the effect of combinations of individual maldistribution sources is investigated for different evaporator sizes and outdoor temperatures. It is shown that a decrease in cooling capacity and coefficient of performance by flow maldistribution can be compensated by the control of individual channel superheat. Alternatively, a larger evaporator may be used.

  17. Analysis of internal helically finned tubes for parabolic trough design by CFD tools

    International Nuclear Information System (INIS)

    Highlights: ? Parabolic trough collectors life improvement by internally finned tubes. ? Solar thermal oil degradation reduction by homogenization of temperature profile in parabolic trough collectors. ? Efficiency enhancement of parabolic trough collectors by finned tubes. ? CFD analysis of finned parabolic trough collector tubes. -- Abstract: This paper has analysed the effect of the utilization of internal finned tubes for the design of parabolic trough collectors with computational fluid dynamics tools. Our numerical approach has been qualified with the computational estimation of reported experimental data regarding phenomena involved in finned tube applications and solar irradiation of parabolic trough collector. The application of finned tubes to the design of parabolic trough collectors must take into account features as the pressure losses, thermal losses and thermo-mechanical stress and thermal fatigue. Our analysis shows an improvement potential in parabolic trough solar plants efficiency by the application of internal finned tubes.

  18. Experimental study on thermal performance of filled-type evacuated tube with U-tube

    Science.gov (United States)

    Liang, Ruobing; Ma, Liangdong; Zhang, Jili; Zhao, Dan

    2012-06-01

    The filled-type evacuated tube with U-tube, in which the filled layer is used to transfer energy absorbed by working fluid in the U-tube, is proposed to eliminate the effect of thermal resistance between the absorber tube and copper fin of the conventional solar collector. In this paper, the thermal performance of the filled-type evacuated tube was researched by means of experimental study. In order to avoid the effect of some uncertain factors, the single collector tube was considered as investigated objective. The test setup of the thermal performance of the filled-type evacuated tube with U-tube was established. The results show that the filled-type evacuated tube with U-tube has a favorable thermal performance compared with the evacuated tube with copper fin. The heat efficiency of filled-type evacuated tube is higher than that of copper fin evacuated tube by 12%. The useful energy gain of filled-type evacuated tube is 22% higher than that of copper fin evacuated tube at the practical irradiance received I T = 800 W/m2 and flow rate M f = 0.005 L/s. In addition, the exergy efficiency of the filled-type evacuated tube is higher than that of copper fin evacuated tube.

  19. A study on the development of fouling evaluation method for finned tube heat exchanger

    International Nuclear Information System (INIS)

    Heat exchangers in nuclear power plants are used for various purposes, such as safe shutdown of nuclear reactor, increase of thermal efficiency, maintenance of temperature inside building, final heat sink, reduction of thermal stress by cold water injection, etc. As operating time of these heat exchangers progresses, fouling generated by water-borne deposits increases and thermal performance decreases. Even though thermal performance tests for heat exchangers without phase change in domestic nuclear power plants have performed with a fixed interval, thermal performance tests for finned tube heat exchangers with condensation have not performed to date. This paper describes the development of fouling evaluation method for finned tube heat exchangers and the result of prototype evaluation for the heat exchanger using the mixture of C3 and N-C4 as a refrigerant

  20. Study made of heat transfer and pressure drop through tubes with internal interrupted fins

    Science.gov (United States)

    Namkoong, D., Jr.

    1967-01-01

    Argon gas flow through an internal interrupted finned tube was investigated to obtain heat transfer and frictional pressure drop data. The results were plotted against the same data for corresponding louvered plate-finned surfaces.

  1. Experimental Investigation of Heat Transfer and Pressure Drop Characteristics of H-type Finned Tube Banks

    Directory of Open Access Journals (Sweden)

    Heng Chen

    2014-11-01

    Full Text Available H-type finned tube heat exchanger elements maintain a high capacity for heat transfer, possess superior self-cleaning properties and retain the ability to effect flue gas waste heat recovery in boiler renovations. In this paper, the heat transfer and pressure drop characteristics of H-type finned tube banks are studied via an experimental open high-temperature wind tunnel system. The effects of fin width, fin height, fin pitch and air velocity on fin efficiency, convective heat transfer coefficient, integrated heat transfer capacity and pressure drop are examined. The results indicate that as air velocity, fin height and fin width increase, fin efficiency decreases. Convective heat transfer coefficient is proportional to fin pitch, but inversely proportional to fin height and fin width. Integrated heat transfer capacity is related to fin efficiency, convective heat transfer coefficient and finned ratio. Pressure drop increases with the increase of fin height and fin width. Finally, predictive correlations of fin efficiency, Nusselt number and Euler Number are developed based on the experimental data.

  2. Development and production of tubes with inner finning for nuclear power

    International Nuclear Information System (INIS)

    Increased heat transfer due to inner finning of tubes results in increasing the life of tubes in steam generators of sodium cooled reactors and in limiting unfavourable effects of temperature changes on the tubes. The development was therefore commenced of tubes with inner longitudinal and inner helical fins. The technology of drawing tubes on linear drawing benches using a short cylindrical mandrel was accepted as most suitable. The effect was studied of the geometry of tools and fixtures and the relationships were tested between the size of drawing reduction of the diameter and the initial wall thickness of different tubes. It was found that the increase in the fin height depended on the size of the wall thickness reduction. Tubes 18 mm in diameter, 3 mm in wall thickness and 0.5 and 1 mm in fin height, 2 mm in fin width and 5.5 to 7 m in length, and tubes with helical fins of 0.5 mm and 1 mm in fin height and with a pitch of 200, 250 and 300 mm were subject to tests confirming that for longitudinal fins heat transfer improved by 20% and for helical fins by 50%. (Z.M.)

  3. Flow/heat transfer analysis and shape optimization of a heat exchanger with internally finned tube

    International Nuclear Information System (INIS)

    Analyses of flow and heat transfer characteristics and shape optimization of internally finned circular tubes have been performed for three-dimensional periodically fully developed turbulent flow and heat transfer. CFD and mathematical optimization are coupled in order to optimize the shape of heat exchanger. The design variables such as fin widths (d1, d2) and fin height (h) are numerically optimized by minimizing the pressure loss and maximizing the heat transfer rate for limiting conditions of d1=0.2?1.5 mm, d2=0.2?1.5 mm, and h=0.2?1.5 mm. Due to the periodic boundary conditions along main flow direction, the three layers of meshes are considered. The flow and thermal fields are predicted using the finite volume method and the optimization is carried out by means of the Sequential Quadratic Programming(SQP) method which is widely used in the constrained nonlinear optimization problem

  4. Effects of biofouling on air-side heat transfer and pressure drop for finned tube heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Pu, Hui; Ding, Guo-liang; Ma, Xiao-kui; Hu, Hai-tao [Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, No. 800 Dongchuan Road, Shanghai 200240 (China); Gao, Yi-feng [International Copper Association Shanghai Office, 381 Huaihaizhong Road, Shanghai 200020 (China)

    2009-08-15

    Experimental investigations on the effects of biofouling on air-side heat transfer and pressure drop for three biofouled finned tube heat exchangers and one clean finned tube heat exchanger were performed. Artificial accelerated method of microorganism growth on the fin surface was used for simulating the biofouled finned tube heat exchangers. Experimental results indicate that the effects of biofouling on the air-side heat transfer coefficient decreases 7.2% at 2.0 m/s when the biofouled area ratio is 10%, while it decreases 15.9% at 2.0 m/s when the biofouled area ratio is 60%, and biofouling causes a 21.8% {proportional_to} 41.3% increase in pressure drop when the air velocity is between 0.5 and 2.0 m/s. The increase of inlet air velocity is helpful to improve the long-term performance of finned tube heat exchanger. Biofouling makes the hydrophilic coating failure, and the condensation water easily converges on the fin surface where biofouling grows. (author)

  5. Steam generator tube performance

    International Nuclear Information System (INIS)

    A review of the performance of steam generator tubes in 116 water-cooled nuclear power reactors showed that tubes were plugged at 54 (46 percent) of the reactors. The number of tubes removed from service decreased from 4 692 (0.30 percent) in 1981 to 3 222 (0.20 percent) in 1982. The leading causes of tube failures were stress corrosion cracking from the primary side, stress corrosion cracking (or intergranular attack) from the secondary side and pitting corrosion. The lowest incidence of corrosion-induced defects from the secondary side occurred in reactors that have used only volatile treatment, with or without condensate demineralization

  6. Steam generator tube performance

    International Nuclear Information System (INIS)

    A review of the performance of steam generator tubes in 110 water-cooled nuclear power reactors showed that tubes were plugged at 46 (42 percent) of the reactors. The number of tubes removed from service increased from 1900 (0.14 percent) in 1980 to 4692 (0.30 percent) in 1981. The leading causes of tube failures were stress corrosion cracking from the primary side, stress corrosion cracking (or intergranular attack) from the secondary side and pitting corrosion. The lowest incidence of corrosion-induced defects from the secondary side occurred in reactors that used all-volatile treatment since start-up. At one reactor a large number of degraded tubes were repaired by sleeving which is expected to become an important method of tube repair in the future

  7. Research on heat transfer and pressure drop characteristics of integral pin-fin tube

    International Nuclear Information System (INIS)

    Taking lubricating oil as the heat transfer medium, heat transfer and pressure drop characteristics of integral pin-fin tubes were researched both in terms of theoretical and experiments. The results can provide a reference for pin-fin tube optimization. Under the condition of heat transfer medium longitudinally flushing the heat exchanger tube surface, the heat transfer and resistance experiments of plain tube and integral pin-fin tubes (in three different length) were carried out in the present work. The results show that the integral pin-fin tubes can improve the heat transfer ability of lubricating oil. The oil flow fluctuation caused by integral pin-fin tubes is intense and the heat transfer intensity of integral pin-fin tubes is 2-6 times of plain tube at the same experiment condition. The length of fin makes main influence on pressure drop, and the pressure drop curve turns around when the values of Reynolds number reaches to 300. (authors)

  8. Laminar fluid flow and heat transfer in a fin-tube heat exchanger with vortex generators

    Energy Technology Data Exchange (ETDEWEB)

    Yanagihara, J.I.; Rodriques, R. Jr. [Polytechnic School of Univ. of Sao Paolo, Sao Paolo (Brazil). Dept. of Mechanical Engineering

    1996-12-31

    Development of heat transfer enhancement techniques for fin-tube heat exchangers has great importance in industry. In recent years, heat transfer augmentation by vortex generators has been considered for use in plate fin-tube heat exchangers. The present work describes a numerical investigation about the influence of delta winglet pairs of vortex generators on the flow structure and heat transfer of a plate fin-tube channel. The Navier-Stokes and Energy equations are solved by the finite volume method using a boundary-fitted coordinate system. The influence of vortex generators parameters such as position, angle of attack and aspect ratio were investigated. Local and global influences of vortex generators in heat transfer and flow losses were analyzed by comparison with a model using smooth fin. The results indicate great advantages of this type of geometry for application in plate fin-tube heat exchangers, in terms of large heat transfer enhancement and small pressure loss penalty. (author)

  9. Flow structure of natural dehumidification over a horizontal finned-tube

    Science.gov (United States)

    Hirbodi, Kamran; Yaghoubi, Mahmood

    2015-08-01

    In the present study, structure of water drops formation, growth, coalescence and departure over a horizontal finned-tube during natural dehumidification is investigated experimentally. Starting time of repelling the drops as well as heat transfer rate and the rate of dripping condensates in quasi-steady-state conditions are presented. Furthermore, cold airflow pattern around the horizontal finned-tube is visualized by using smoke generation scheme during natural dehumidification process. The finned-tube has a length of 300 mm, and inner and outer fin diameters, fin thickness and fin spacing are 25.4, 56, 0.4 and 2 mm, respectively. The tests are conducted in an insulated control room with dimensions of 5.8 m × 3 m × 4 m. Ambient air temperature, relative humidity and fin base temperature are selected from 25 to 35 °C, from 40 to 70 % and from 4 to 8 °C, respectively. Observations show that natural condensation from humid air over the test case is completely dropwise. Droplets only form on the edge of the fin and lateral fin surfaces remain almost dry. Dehumidification process over the tested finned-tube is divided into four stages; nucleation, formation, growth and departure of drops. It is also observed that the condensate inundation leaves the tube bottom in the form of droplets. Smoke visualization depicts that humid airflows downward around the cold finned-tube surface without noticeable turbulence and separation in the initial stages of dehumidification process. But the airflow has some disturbances in the intermediate stage and especially during drop departure on the edge of the fins.

  10. Analysis of refrigerant mal-distribution : in fin-and-tube evaporators

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian

    2009-01-01

    Refrigerant mal-distribution in fin-and-tube evaporators for residential air-conditioning is investigated numerically in this paper. Essentially the influence of refrigerant mal-distribution on capacity of an evaporator is reported. In order to investigate, a model of a fin-and-tube evaporator is developed in the object-oriented modeling language Modelica. The evaporator model is a dynamic distributed one-dimensional homogeneous model, but will be used here to present results in steady state. Fin-and-tube evaporators usually have a complex circuitry, however the evaporator will be simplified to be two straight tubes. The refrigerant maldistribution is then induced to the evaporator by varying the vapor quality at the inlet to each tube and the air-flow across each tube. Finally it is shown that mal-distribution can be compensated by an intelligent distributor, that ensures equal superheat temperature in both tubes. The refrigerant is R410a.

  11. Burnout in the boiling of water and freon-113 on tubes with annular fins

    International Nuclear Information System (INIS)

    This paper presents the results of numerical calculations of burnout heat flux associated with the boiling of Freon-113 and water on an annular fin of constant thickness which have been approximated by simple analytical relations. These are used to calculate the critical burnout parameters of tubes with an annular fin assembly. The calculated data may be used for the analysis of tubes with an annular fin assembly over a wide range of variation of the thermophysical properties of the material and geometrical parameters of the fin assembly

  12. High temperature design of finned-tube sodium-to-air heat exchanger in a sodium test loop

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyeong-Yeon, E-mail: hylee@kaeri.re.kr; Eoh, Jae-Hyuk; Lee, Yong-Bum

    2013-12-15

    Highlights: • High temperature design of finned-tube heat exchanger (FHX) in SFR were conducted. • Full 3D FE analyses for the sodium-to-air heat exchanger unit were performed. • Stress levels of the FHX unit based on full 3D analyses were not severe. • Creep–fatigue damage as per design rules was evaluated to be within allowable limit. - Abstract: A sodium test loop called ‘SELFA’ (sodium thermal-hydraulic experiment loop for finned-tube sodium-to-air heat exchanger) for simulating thermal hydraulic behavior of the FHX (finned-tube sodium-to-air heat exchanger) unit in a Korean prototype sodium-cooled fast reactor is planned to be constructed at KAERI (Korea Atomic Energy Research Institute). In this study, the elevated temperature design for a model FHX and creep–fatigue damage evaluation have been conducted for the model according to the design codes of ASME section III subsection NH and RCC-MRx based on full 3D finite element analyses. Design optimization for the finned-tubes and tube arrangements in the scaled-down FHX has been performed. The materials of the FHX and piping systems are austenitic stainless steel type 316. The design temperature of the SELFA test loop is 600 °C and the design pressure is 1 MPa. The damage evaluation results have shown that no creep–fatigue damage occurs in the present design of the FHX under the intended test conditions.

  13. Steam generator tube performance

    International Nuclear Information System (INIS)

    The performance of steam generator tubes in water-cooled nuclear power reactors has been reviewed for 1980. Tube defects occurred at 38% of the 97 reactors surveyed. This is a marginal improvement over 1979 when defects occurred at 41% of the reactors. The number of failed tubes was also lower, 0.14% of the tubes in service in 1980 compared with 0.20% of those in service in 1979. Analysis of the causes of these failures indicates that stress corrosion cracking was the leading failure mechanism. Reactors that used all-volatile treatment of secondary water, with or without full-flow condensate demineralization since start-up showed the lowest incidence of corrosion-related defects

  14. Investigation on flow and heat transfer for a staggered tube bank of low finned tubes at high Reynolds numbers

    International Nuclear Information System (INIS)

    A ten rows deep tube bundle with 15 tubes in each row all of which were cooled has been tested (root diameter of the tubes D = 22,2 mm, fin height h = 1,46 mm, fin pitch t = 1,25 mm). The mean heat transfer coefficient and pressure drop has been determined in the range of 5 .(period on line) 103 5. The results were compared with semiempirical formulas given by Th.E. Schmidt, A. Skrinska and J. Stasiulewitschius and W. Kast. In the same test series the heat transfer of each row has been measured. Besides that the influence of half tubes which were fixed at the walls of the duct on heat transfer and flow resistance was investigated. Finally was made an attempt to judge about the advantes due to finning the tubes. (orig.)

  15. Studi Analitik dan Numerik Perpindahan Panas pada Fin Trapesium (Studi Kasus pada Finned Tube Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Ahmad Zaini

    2013-09-01

    Full Text Available Penambahan fin pada pipa penukar kalor merupakan suatu upaya memperbesar perpindahan kalor konduksi dan konveksi, dengan cara memperluas bidang geometri. Pada penelitian ini dianalisa secara analitik dan numerik perpindahan kalor pada fin dengan profil longitudinal tidak seragam atau berubah terhadap jarak dari dasar fin, dengan memvariasikan ketebalan ujung fin. Hasil dari kedua studi ini tidak jauh berbeda, pada keduanya menjelaskan bahwa fin dengan ketebalan ujung 0,9 mm (fin trapesium terbalik paling baik dari 5 variasi lainnya; serta perubahan temperatur paling besar terjadi pada sepertiga pertama dari panjang  fin, ini artinya pelepasan kalor terbesar terjadi pada daerah tersebut. Perbedaannya adalah pada persentase penurunan temperatur sepanjang  fin terhadap temperatur dasar fin, untuk ketebalan 0,9 mm pada studi analitik sebesar 91,92% dan pada studi numerik sebesar 91,78%. Hal ini berarti metode penyelesaian persamaan diferensial orde 2 dengan koefisien variabel dengan cara pembedahan koefisien variabel pada ODE, sudah benar dan valid. Namun bila ditinjau dari waktu yang diperlukan untuk komputasinya, studi analitik membutuhkan waktu lebih lama. Waktu yang diperlukan dalam komputasinya tergantung dari fungsi koefisien variabel.

  16. Experimental analysis of ammonia condensation on smooth and integral-fin titanium tubes

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Seara, Jose; Uhia, Francisco J.; Diz, Ruben [Area de Maquinas y Motores Termicos, E.T.S. de Ingenieros Industriales, University of Vigo, Campus Lagoas-Marcosende No 9, 36310 Vigo (Spain)

    2009-09-15

    This paper reports on the experimental research conducted to study the condensation of ammonia on smooth and integral-fin (32 fpi) titanium tubes of 19.05 mm outer diameter. Experiments were carried out at saturation temperatures of 30, 35, 40 and 45 C and wall subcoolings from 1 to 8 C. The results show that the condensation coefficients on the smooth tubes are well predicted by the Nusselt theory with an average error of +0.66% and within a deviation between -6.6% and +8.3%. The enhancement factors provided by the integral-fin tubes range from 0.77 to 1.22. The low enhancement factors are due to the high condensate retention between fins, which brings about flooded fractions of the tube perimeter from 62.9% to 73.2%, and the low thermal conductivity of titanium. The Briggs and Rose [1994. Effect of fin efficiency on a model for condensation heat transfer on a horizontal, integral-fin tube. Int. J. Heat Mass Transfer 37, 457-463.] model, which accounts for the conduction in the fins, predicts the experimental data with a mean overestimation of 20%. The analysis of the partial thermal resistances in the overall heat transfer process points out the convenience of enhancing the outside ammonia condensation when high water velocities are considered inside the tubes. (author)

  17. The numerical analysis of the flow fields near fin surface of a plate fin-oval tube heat exchanger with delta wing vortex generators

    International Nuclear Information System (INIS)

    In present study, the flow field near the fin surface of plate fin - oval tube heat exchanger with delta wing vortex generator was numerically analyzed. As results, the well developed vortex behind delta wing was observed. These vortex can improve heat transfer fin surface behind delta wing vortex generators

  18. Comparative design evaluation of plate fin heat exchanger and coiled finned tube heat exchanger for helium liquefier in the temperature range of 300-80 K

    International Nuclear Information System (INIS)

    Present indigenous helium liquefaction system at RRCAT uses the cross-counter flow coiled-finned tube heat exchangers developed completely from Indian resources. These coiled-finned tube heat exchangers are mainly suitable up to medium capacity helium liquefiers. For large capacity helium liquefier, plate fin heat exchangers are more suitable options. This paper presents the comparative evaluation of the design of both types of heat exchangers in the temperature range of 300-80 K for helium liquefier. (author)

  19. Design and optimization of coil finned-tube heat exchangers for cryogenic applications

    Science.gov (United States)

    Gupta, Prabhat Kumar; Kush, P. K.; Tiwari, Ashesh

    2007-05-01

    Coiled finned-tube heat exchangers have been used in small and medium helium refrigerators/liquefiers, miniature J-T refrigeration systems for many years. The efficiency of these cryogenic systems strongly depends on the thermal and pressure drop performance of these heat exchangers. A considerable improvement in the performance of heat exchanger is possible by choosing an appropriate geometrical configuration for a given process requirement. In the present study, geometry of heat exchanger has been derived taking into consideration the clearance provided for manufacturing of the heat exchangers and an optimized geometrical configurations have been find out. The results show the possibility of adjusting the thermal and pressure drop performance by varying the clearance. The predictions of four end temperatures from present design method have been compared with the actual experimental results of one of the prototypes fabricated in our lab.

  20. Numerical Investigation of Air-Side Heat Transfer and Pressure Drop in Circular Finned-Tube Heat Exchangers

    OpenAIRE

    Mon, Mi Sandar

    2009-01-01

    A three-dimensional numerical study is performed to investigate the heat transfer and pressure drop performance on the air-side of circular finned tube bundles in cross flow. New heat transfer and pressure drop correlations for the air-cooled heat exchangers have been developed with the Reynolds number ranging from 5000 to 70000. The heat transfer and pressure drop results agree well with several existing experimental correlations. In addition, the influence of the geometric parameters on the...

  1. Local Heat Transfer Characteristics on Fin Surface of Plate Fin-Oval Tube with Delta Wing Vortex Generators

    International Nuclear Information System (INIS)

    In the present study, the effect of delta-wing vortex generators(DWVG) on the local heat transfer of the plate fin-oval tube was experimentally analyzed for Reynolds numbers for 2000, 2500 and 3200. The local heat transfer coefficient of the fin surface for four type DWVGs was measured by the naphthalene sublimation technique. As the results, the distribution of the heat transfer coefficient at rear of DWVGs showed longitudinal contours for common flow down DWVGs and wavy contours for common flow up DWVGs. The distribution showed many cell type contours at near wall and downstream for all DWVGs. Compared to case without DWVGs in present experimental tests, all DWVGs showed the best enhancement of heat transfer at Re=2000. Of 4 cases of DWVGs, D type showed the best enhancement of heat transfer

  2. Studi Eksperimen Analisa Performa Compact Heat Exchanger Louvered Fin Flat Tube untuk pemanfaatan Waste Energy

    Directory of Open Access Journals (Sweden)

    Taqwim Ismail

    2014-03-01

    Full Text Available Waste Heat Recovery merupakan instalasi yang digunakan untuk memanfaatkan kembali waste energy seperti exhaust gas. Penelitian dilakukan pada compact heat exchanger tipe louvered fin flat tube sebagai salah satu komponen penyusun waste heat recovery system. Eksperimen dilakukan dengan mendesain compact heat exchanger tipe louvered fin flat tube kemudian dilakukan pengujian pada compact heat exchanger yang telah didesain. Pengujian dilakukan dengan memberikan tiga variasi kecepatan putaran fan sisi exhaust gas, yaitu 0.2, 0.3, dan 0.4 m/s untuk mengetahui unjuk kerja yang berbeda dari compact heat exchanger yang telah didesain.  Hasil yang didapatkan dari studi eksperimen ini adalah dimensi dari compact heat exchanger tipe louvered fin flat tube dan beberapa parameter yang menunjukkan unjuk kerja dari compact heat exchanger seperti nilai heat transfer baik dari sisi air maupun sisi exhaust gas, effectiveness, number of transfer unit (NTU, overall heat transfer coefficient, dan  ?TLMTD dari compact heat exchanger.

  3. HEAT TRANSFER AND FLUID FLOW ANALYSIS IN PLATE-FIN AND TUBE HEAT EXCHANGERS WITH DIFFERENT SHAPED VORTEX GENERATORS

    Directory of Open Access Journals (Sweden)

    K.Thirumalai kannan

    2012-03-01

    Full Text Available Numerical analyses were carried out to study the heat transfer and flow in the plate-fin and tube heat exchangers with different shaped vortex generators mounted behind the tubes. The effects of different span angles a (? = 30°, 45° and 60° are investigated in detail for the Reynolds number ranging from 500 to 2500. Numerical simulation was performed by computational fluid dynamics of the heat transfer and fluid flow. The results indicated that the triangle shaped winglet is able to generate longitudinal vortices and improve the heat transfer performance in the wake regions. The case of ? = 45° provides the best heat transfer augmentation than rectangle shape winglet generator in case of inline tubes. Common flow up configuration causes significant separation delay, reduces form drag, and removes the zone of poor heat transfer from the near wake of the tubes.

  4. High Temperature of Finned-tube Sodium-to-Air Heat Exchanger in the SELFA Test Loop

    International Nuclear Information System (INIS)

    A medium-scale sodium test loop named as the ‘SELFA’(Sodium Thermal?hydraulic Experiment Loop for Finned?tube Sodium?to?Air heat exchanger) for simulating thermal hydraulic behavior of the FHX (Finned-tube Sodium-to-Air heat Exchanger) in Korean prototype sodium-cooled fast reactor is planned to be constructed at KAERI (Korea Atomic Energy Research Institute). In this study, elevated temperature design for the FHX and creep-fatigue damage evaluation have been conducted according to the design codes of ASME section III subsection NH and RCC-MRx based on full 3D finite element analyses. Design optimization for the finned-tubes and tube arrangements in the scaled-down FHX mock-up has been performed. The materials of the FHX and piping systems are austenitic stainless steel 316, the design temperature and of the SELFA test loop is 600°C and design pressure is 1MPa. The damage evaluation results have shown that no creep-fatigue damage occurrs in the present design of the FHX under the intended test conditions. (author)

  5. Comparison of fin-and-tube interlaced and face split evaporators with flow maldistribution and compensation

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian

    2013-01-01

    Flow maldistribution in fin-and tube evaporators for residential air-conditioning is investigated by numerical simulation. In particular, the interlaced and the face split evaporator are compared in flow maldistribution conditions. The considered sources of maldistribution are the liquid/vapor distribution and the airflow distribution. Furthermore, compensation of flow maldistribution by control of individual channel superheat is studied for each evaporator type. It is shown that the interlaced evaporator is better at flow maldistribution than the face split evaporator. However, if individual channel superheats are controlled, the face split evaporator achieves the best performance, i.e. an increase of 7% in overall UA-value and 1.6–2.4% in COP compared to the interlaced evaporator without compensation.

  6. Heat transfer characteristics of a new helically coiled crimped spiral finned tube heat exchanger

    Science.gov (United States)

    Srisawad, Kwanchanok; Wongwises, Somchai

    2009-02-01

    In the present study, the heat transfer characteristics in dry surface conditions of a new type of heat exchanger, namely a helically coiled finned tube heat exchanger, is experimentally investigated. The test section, which is a helically coiled fined tube heat exchanger, consists of a shell and a helical coil unit. The helical coil unit consists of four concentric helically coiled tubes of different diameters. Each tube is constructed by bending straight copper tube into a helical coil. Aluminium crimped spiral fins with thickness of 0.5 mm and outer diameter of 28.25 mm are placed around the tube. The edge of fin at the inner diameter is corrugated. Ambient air is used as a working fluid in the shell side while hot water is used for the tube-side. The test runs are done at air mass flow rates ranging between 0.04 and 0.13 kg/s. The water mass flow rates are between 0.2 and 0.4 kg/s. The water temperatures are between 40 and 50°C. The effects of the inlet conditions of both working fluids flowing through the heat exchanger on the heat transfer coefficients are discussed. The air-side heat transfer coefficient presented in term of the Colburn J factor is proportional to inlet-water temperature and water mass flow rate. The heat exchanger effectiveness tends to increase with increasing water mass flow rate and also slightly increases with increasing inlet water temperature.

  7. Hydrodynamic Performance of a Flexible Fish Pectoral Fin

    Science.gov (United States)

    Mittal, Rajat; Dong, Haibo; Bozkurttas, Meliha; Lauder, George; Madden, Peter

    2006-11-01

    Numerical simulations have been used to examine in detail the hydrodynamic performance of a pectoral fin of a bluegill sunfish. The pectoral fin of this fish is highly flexible and undergoes significant shape and area change during its flapping cycle. The numerical simulations employ a 3D immersed boundary solver that allows us to examine in detail the hydrodynamics of the fin. Simulations reveal that the fish uses the fin flexibility to produce a highly complex and asymmetric stroke that does not fit any of the classic notions of ``paddling'' or ``flapping.'' The numerical simulations clearly reveal the distinct vortex structured produced by the fin and the connection between the vortex structures and hydrodynamic performance is examined. Finally, comparison between a flexible fish fin and a rigid flapping foil allows us to assess the benefits of flexibility on the hydrodynamic performance.

  8. The influence of the finned-tube assembly on the dimensions of natural-draft dry-type cooling towers

    International Nuclear Information System (INIS)

    For various heat exchanger systems the required heights of the towers are evaluated by means of a simplifying mathematical model for dimensioning cooling towers. The characteristics of the cooling systems are for each case taken from literature. The number of tube banks of the heat exchanger systems in flow direction was optimized using the operational data of the Schnehausen dry-type cooling tower. It may be assumed that by changing the tube configuration the performance of very closely spaced, aligned finned systems can be considerably improved. (GL)

  9. Analysis of flow maldistribution in fin-and-tube evaporators for residential air-conditioning systems

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl

    2011-01-01

    This thesis is concerned with the effects of flow maldistribution in fin-and-tube A-coil evaporators for residential air-conditioning and compensation potentials with regards to system performance. The goal is to create a better understanding of flow maldistribution and the involved physical phenomenons. Moreover, the study investigates the individual and combined effects of non-uniform inlet liquid/vapor distribution, different feeder tube bending and non-uniform airflow. In addition, the possible compensation of these maldistribution sources is investigated by control of individual channel superheat by distributing individual channel mass flow rate continuously (perfect control). The compensation method is compared to the use of a larger evaporator in order to study their trade-off in augmenting system performance (cooling capacity and COP). The studies are performed by numerical modeling in the object-oriented programming language Modelicar and by using the commercial modeling environment Dymola 7.4 (2010). The evaporator model needs to be capable of predicting the flow distribution and circuitry effects, and for these reasons the dynamic distributed one-dimensional mixture two-phase flow model is implemented. The model is verified in steady state with commercial software Coil-Designer (Jiang et al., 2006) and compared to steady state experiments with acceptable results considering the unknown degrees of flow maldistribution for these experiments. Furthermore, the system dynamics in the model were validated and showed that a slip flow model need be used. A test case 8.8 kW residential air-conditioning system with R410A as refrigerant is chosen as baseline for the numerical investigations, and the simulations are performed at standard rating conditions from ANSI/AHRI Standard 210/240 (2008). The investigations are performed on a simplified evaporator tube circuitry (two straight channels), a face split evaporator circuitry and an interlaced evaporator circuitry. The first case is a generic study and serves to provide general results independent of specific type of tube circuitry. The second and third cases are standard tube circuitry designs and these results are thus tube circuitry specific. In addition, a novel method of compensating flow maldistribution is analyzed, i.e. the discontinuous liquid injection principle. The method is based upon the recently developed EcoFlowTM valve by Danfoss A/S, and controls the individual channel superheat by distributing individual mass flow rate discontinuously (on/off injection). The results in this thesis show that flow maldistribution decreases system performance in terms of cooling capacity and COP, but may be compensated significantly by control of individual channel superheat. The generic study (two straight channels) shows that the airflow maldistribution has the largest effect, whereas the liquid/vapor maldistribution has smaller effect and the different feeder tube bending has a minor effect on system performance. The comparison between the face split and interlaced circuitry shows that the face split evaporator performs better at uniform flow conditions, whereas the interlaced evaporator performs better at flow maldistribution conditions. When compensating, the face split evaporator always performs best. A similar result is also obtained as the airflow profile across the A-coil evaporator was predicted by means of CFD simulation software STAR-CD 3.26 (2005) and applied in the numerical model. The main reason for the better face split evaporator performance at uniform conditions or when compensating, is that the superheated "weak" zones with low UA-value is located in the first tube row, where the heat transfer driving potential (temperature difference) is highest. The discontinuous liquid injection principle showed that the cycle time is an important parameter for the performance of this compensation method. The cycle time is essentially the time it takes for distributing mass flow to each evaporator channels. It should be kept as low as possible. Furthermore, it is bett

  10. Degradation of finned tubes heat exchangers in presence of non condensable gases and aerosols

    International Nuclear Information System (INIS)

    Full text of publication follows: If a severe accident occurs in a nuclear power plant, then large amounts of steam and aerosols will enter to the containment, increasing the pressure and the temperature inside the containment building. To reduce these thermal and pressure loads, the next generation of European Passive Nuclear Power Plants, incorporates into the containment passive heat exchangers (HX) driven by natural circulation. These passive HX condense the steam inside the containment and transport by natural circulation the heat to a large pool with capability to act as a heat sink at least during 72 hours. These innovative passive systems consist of several units of horizontal or slightly inclined finned tubes bundles internally cooled by water. The cooling water is heated inside the tubes by the condensation heat removed from the containment and moves by natural circulation to a large pool located outside the containment. The main problem that arises in this kind of HX, is the degradation in the heat transfer produced by the non-condensable gases and the aerosols that are present in large amounts after a severe accident inside the containment. This degradation can increase the containment loads after a severe accident and we must be able to predict this effect as better as possible. This paper presents a mechanistic model to predict the steam condensation on containment finned tube heat exchangers in the presence of non-condensable gases (NC) and aerosols. The total thermal resistance from the bulk gas to the coolant is formulated as a parallel combination of the convective and condensation gas resistances coupled in series to those of condensate layer, the aerosol fouling layer, the wall, and the coolant. The condensate layer thermal resistance is calculated by means of an Adamek-based condensation model. The aerosol fouling layer is computed based on diffusiophoresis, settling and impaction mechanisms. The gas mixture (Steam plus NC) thermal resistance is formulated based on a diffusion layer modeling. Finally this paper presents a Monte Carlo method implemented in the Fortran code TAEROSOL that is able to compute the amount of aerosol mass that is deposited by impaction on the top of the finned tubes. The model results are compared with available experimental data of the CONGA European project. Finally we want to mention that Monte Carlo calculations and fluid flow calculations with the code TAEROSOL were performed to compute the amount of aerosols deposited on the top of the fins by impaction during the aerosol phase of Suckow et al. experiments. Also we compute the aerosol mass deposited by diffusiophoresis and settling. The calculations performed show that the mass deposited by settling is always smaller than 3 g in all the cases, and that impaction and diffusiophoresis mechanisms are the main deposition mechanisms for aerosols in CONGA experiments. (authors)

  11. Optimum parameters of transversely finned tubes in the case of simultaneous sooling by natural convection and radiations

    International Nuclear Information System (INIS)

    The optimum parameters of minimum-weight finned tubes for the case of heat transfer by free convection and radiation are determined using the mathematical model with boundary conditions of the 3-type by the method of calculational experiment. The effects of the coolant and air temperatures diameter and thickness of the bimetallic wall, contamination and other factors on optimal finning parameters are investigated. It is obtained that for the case of heat transfer by free convection and radiation, the optimum finning parameters for the heat transfer surface of minimum-weight tubes by absolute value are larger than those of tube finning with forced convection

  12. Effect of tube finning coefficient and straggered arranged bundle configuration on heat transfer intensity in a gas flow

    International Nuclear Information System (INIS)

    Experimental data on heat transfer of finning tubes transversely stream-lined by the gas flow in a gas-liquid heat exchangers are generalized. Effect of staggered bundle geometrical parameters and tube finning coefficient on the heat transfer in a gas flow is considered

  13. Steam generator tube performance

    International Nuclear Information System (INIS)

    A survey of steam generator operating experience for 1986 has been carried out for 184 pressurized water and pressurized heavy-water reactors, and 1 water-cooled, graphite-moderated reactor. Tubes were plugged at 75 of the reactors (40.5%). In 1986, 3737 tubes were plugged (0.14% of those in service) and 3148 tubes were repaired by sleeving. A small number of reactors accounted for the bulk of the plugged tubes, a phenomenon consistent with previous years. For 1986, the available tubesheet sludge data for 38 reactors has been compiled into tabular form, and sludge/deposit data will be incorporated into all future surveys

  14. A study of the air-side heat transfer and pressure drop characteristics of tube-fin 'no-frost' evaporators

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Jader R. Jr.; Melo, Claudio; Hermes, Christian J.L.; Waltrich, Paulo J. [POLO - National Institute of Science and Technology of Refrigeration and Thermophysics, Federal University of Santa Catarina, 88040-900, Florianopolis, SC (Brazil)

    2009-09-15

    A study is presented on the influence of the air flow rate and surface geometry on the thermal-hydraulic performance of commercial tube-fin 'no-frost' evaporators. A specially constructed wind-tunnel calorimeter was used in the experiments from which data on the overall thermal conductance, pressure drop, Colburn j-factor and Darcy friction factor, f, were extracted. Eight different evaporator samples with distinct geometric characteristics, such as number of tube rows, number of fins and fin pitch were tested. Semi-empirical correlations for j and f are proposed in terms of the air-side Reynolds number and the finning factor. A discussion is presented on the performance of the evaporators with respect to specific criteria such as the pumping power as a function of heat transfer capacity and the volume of material in each evaporator. (author)

  15. Burnout experiments on the externally-finned swirl tube for steady-state and high-heat flux beam stops

    International Nuclear Information System (INIS)

    An experimental study to develop beam stops for the next generation of neutral beam injectors was started, using an ion source developed for the JT-60 neutral beam injector. A swirl tube is one of the most promising candidates for a beam stop element which can handle steady-state and high-heat flux beams. In the present experiments, a modified swirl tube, namely an externally-finned swirl tube, was tested together with a simple smooth tube, an externally finned tube, and an internally finned tube. The major dimensions of the tubes are 10 mm in outer-diameter, 1.5 mm in wall thickness, 15 mm in external fin width, and 700 mm in length. The burnout heat flux (CHF) normal to the externally finned swirl tube was 4.1±0.1 kW/cm2, where the Gaussian e-folding half-width of the beam intensity distribution was about 90 mm, the flow rate of the cooling water was 30 l/min, inlet and outlet gauge pressures were about 1 MPa and 0.2 MPa, respectively, and the temperature of the inlet water was kept to 200C during a pulse. A burnout heat flux ratio, which is defined by the ratio of the CHF value of the externally-finned swirl tube to that of the externally-finned tube, turned out to be about 1.5. Burnout heat fluxes of the tubes with a swirl tape or internal fins increase linearly with an increase of the flow rate. It was found that the tube with external fins has effects that not only reduce the thermal stress but also improve the characteristics of boiling heat transfer. (orig.)

  16. Conceptual designs and cost estimates of mechanical draft wet/dry and natural draft dry cooling systems using Curtiss-Wright integral fin-tube heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Haberski, R.J.; Bentz, J.C.

    1979-04-01

    This study was performed to establish a conceptual design and cost evaluation of an advanced technology mechanical draft wet/dry and natural draft dry cooling systems for large electric power plants using a high performance integral fin-tube heat transfer surface. This study was part of an overall DOE program to develop and demonstrate advanced concept cooling systems for large electric power plants. The results obtained show significant economic advantages compared to results previously published for conventional cooling systems. These advantages are due to the higher heat transfer and lower pressure loss which occur with the use of the selected multi-port integral fin-tubes.

  17. Flexible nanoscale high-performance FinFETs.

    Science.gov (United States)

    Torres Sevilla, Galo A; Ghoneim, Mohamed T; Fahad, Hossain; Rojas, Jhonathan P; Hussain, Aftab M; Hussain, Muhammad Mustafa

    2014-10-28

    With the emergence of the Internet of Things (IoT), flexible high-performance nanoscale electronics are more desired. At the moment, FinFET is the most advanced transistor architecture used in the state-of-the-art microprocessors. Therefore, we show a soft-etch based substrate thinning process to transform silicon-on-insulator (SOI) based nanoscale FinFET into flexible FinFET and then conduct comprehensive electrical characterization under various bending conditions to understand its electrical performance. Our study shows that back-etch based substrate thinning process is gentler than traditional abrasive back-grinding process; it can attain ultraflexibility and the electrical characteristics of the flexible nanoscale FinFET show no performance degradation compared to its rigid bulk counterpart indicating its readiness to be used for flexible high-performance electronics. PMID:25185112

  18. Flexible nanoscale high-performance FinFETs

    KAUST Repository

    Sevilla, Galo T.

    2014-10-28

    With the emergence of the Internet of Things (IoT), flexible high-performance nanoscale electronics are more desired. At the moment, FinFET is the most advanced transistor architecture used in the state-of-the-art microprocessors. Therefore, we show a soft-etch based substrate thinning process to transform silicon-on-insulator (SOI) based nanoscale FinFET into flexible FinFET and then conduct comprehensive electrical characterization under various bending conditions to understand its electrical performance. Our study shows that back-etch based substrate thinning process is gentler than traditional abrasive back-grinding process; it can attain ultraflexibility and the electrical characteristics of the flexible nanoscale FinFET show no performance degradation compared to its rigid bulk counterpart indicating its readiness to be used for flexible high-performance electronics.

  19. Numerical analysis of fin-tube plate heat exchanger by using CFD technique

    OpenAIRE

    Ahmed F. Khudheyer; Mahmoud Sh. Mahmoud

    2011-01-01

    Three-dimensional CFD simulations are carried out to investigate heat transfer and fluid flow characteristics of a two-row plain fin-and-tube heat exchanger using Open FOAM, an open-source CFD code. Heat transfer and pressure drop characteristics of the heat exchanger are investigated for Reynolds numbers ranging from 330 to 7000. Model geometry is created, meshed, calculated, and post-processed using open source software. Fluid flow and heat transfer are simulated and results compared using ...

  20. Investigation of Scaling Effects on Fish Pectoral Fin Performance

    Science.gov (United States)

    Bozkurttas, Meliha; Dong, Haibo; Mittal, Rajat; Madden, Peter; Lauder, George

    2006-11-01

    Reynolds and Strouhal numbers are two key parameters that can potentially affect the performance of rigid and deformable flapping foils. Flow past a deformable pectoral fin of a fish in steady forward motion (speed of 1 BL/s) is simulated using a Cartesian grid immersed boundary solver. Investigation of the scaling of the performance with these two parameters allows us to gain better insight into the fundamental mechanisms of the thrust production as well as address the practical question of how the performance of a fin is expected to change with changes in size, speed and frequency. It is found that the essential fluid dynamic mechanisms are unchanged with Reynolds number. We observe that although the vortex structures get more complicated with increasing Re, the key features (like the strong tip vortex, leading and trailing edge vortices) are similar in all the cases. On the other hand, the hydrodynamic performance of the fin is found to be quite sensitive to the Strouhal number. A set of numerical simulations of fin gaits synthesized from the POD modes are also carried out. This approach allows us to connect specific features in the fin gait with the observed vortex dynamics and hydrodynamic force production.

  1. Numerical Simulation of Plain Fin-and-Round Tube Heat Exchanger under Frost Condition

    Science.gov (United States)

    Hussein, Amar Ali; Talib, A. R. Abu; Adam, N. M.

    2010-06-01

    Three-dimensional numerical simulations are carried out to investigate the amount of heat transfer of a plain fin-and-four staggered layout and round tube rows for different fin pitch namely 25.4, 12.7, 6.35 and 4.23 mm. The simulations were conducted for two different frost thermal conductivity of 0.1 and 0.3 W/m-1K-1 using FLUENT 6.3 CFD code. The amount of heat transfer of the plain fin-and-round tube heat exchanger under frost condition (0, 1, 2, and 3 mm frost thickness) was investigated. Fluid flow and heat transfer are simulated and results calculated using two turbulence models (k-epsilon, and Transitional SST k-omega), with steady-state solver. Model validation was carried out by comparing the pressure drop of simulated case to experimental results from the literature. Reasonable agreement was found between the present simulations compared to existing numerical study and experimental data.

  2. Experimental Study on the Air-Side Heat Transfer Characteristics of a Spirally- Coiled Circular Fin-Tube Heat Exchanger According to Geometric Parameters

    International Nuclear Information System (INIS)

    The objective of this study is to investigate the air-side heat transfer characteristics of a spirally-coiled circular fin tube heat exchanger for various geometric parameters under non-frosting conditions. The heat transfer characteristics of the heat exchanger were analyzed with respect to heat exchanger geometries, and then, the characteristics were compared with those of rectangular-plate fin-tube heat exchangers with discrete fins. The heat transfer coefficient increased with a decrease in the number of tube rows and an increase in the fin pitch. The optimum length of the L-foot was 2.7 mm. In addition, the heat transfer rate increased with a decrease in the tube pitch and the tube thickness. The heat transfer coefficient of the spirally coiled circular fin-tube heat exchanger was 24.3% higher than that of the rectangular-plate fin-tube heat exchanger

  3. Experimental investigation of forced-convection in a finned rhombic tube of the flat-plate solar collectors

    DEFF Research Database (Denmark)

    Taherian, Hessam; Yazdanshenas, Eshagh

    2006-01-01

    Due to scarcity of literature on forced-convection heat transfer in a solar collector with rhombic cross-section absorbing tubes, a series of experiments was arranged and conducted to determine heat transfer coefficient. In this study, a typical rhombic cross-section finned tube of flat-plate collectors used as the test section. Two correlations were proposed for the Nusselt number as a function of the Reynolds number and the Prandtl number based on hydraulic diameter for various heat fluxes. The temperature distribution along the finned tube for the fluid and the wall were also illustrated.

  4. Numerical estimation of heat transfer characteristics for two-row plate-finned tube heat exchangers with experimental data

    Science.gov (United States)

    Chen, Han-Taw; Lu, Chih-Han; Huang, Yao-Sheng; Liu, Kuo-Chi

    2015-06-01

    This study applies a three-dimensional computational fluid dynamics commercial software in conjunction with various flow models to estimate the heat transfer and fluid flow characteristics of the two-row plate-finned tube heat exchanger in staggered arrangement. The effect of air speed and fin spacing on the results obtained is investigated. Temperature and velocity distributions of air between the two fins and heat transfer coefficient on the fins are determined using the laminar flow and RNG k-? turbulence models. More accurate results can be obtained, if the heat transfer coefficient obtained is close to the inverse results and matches existing correlations. Furthermore, the fin temperature measured at the selected locations also coincides with the experimental temperature data. The results obtained using the RNG k-? turbulence model are more accurate than those using the laminar flow model. An interesting finding is the number of grid points may also need to change with fin spacing and air speed.

  5. Experimental testing of the thermal performance of finned air coolers

    International Nuclear Information System (INIS)

    Finned heat exchangers are often used as regenerators in heat recovery systems or as a heat source for heat pump installations. These exchangers are usually operating as air coolers. Heat is extracted from the air flowing through the heat exchanger. If the fin temperature lies below the dew point at the air inlet, water vapour may be condensed, increasing the thermal performance of the cooler. If the air/water heat exchanger is installed outdoors, the blower is usually mounted directly at the exchaner's case. In general this leads to non-ideal air flow conditions. For the sizing of such components the manufacturers dispose of design rules which are based either on theoretical models or on experiments using a uniform air stream. These rules which are mostly internal codes of the individual companies presumably do not take into account some non-ideal conditions such as an inhomogeneous air flow, a poorly sized blower or an increased pressure drop between the fins due to condensed water vapour. Moreover, these codes are possibly not sophisticated enough to enable a correct sizing of the products for any given condition of operation, especially in heat pumps operating under condensation conditions. Therfore, the Swiss Federal Institute for Reactor Research (EIR) carried out a research program dealing with the thermal performance of commercially available finned air coolers. The results give a strong evidence that the sizing of finned air coolers involving a phase change in one of the heat transfer fluids is not yet a procedure belonging to the common knowledge of most of the manufacturers. Moreover, the correct sizing of the blower is at least as important as the sizing of the finned exchanger itself. However, it is evident that there are companies on the Swiss market which use already reliable design tools. 25 refs., 81 figs., 12 tabs

  6. In-service inspection method for low-finned ferritic stainless steel tubes for new heat exchanger

    International Nuclear Information System (INIS)

    Conventional inner eddy current test cannot obtain sufficient evaluation for low finned ferritic stainless steel tube inspection. The authors tried various methods and developed special partial saturation eddy current method. This paper summarizes typical experimental results of fundamental studies and trials, and introduces developed ECT data acquisition and evaluation system. Moisture Separator Heater (MSH) used in ABWR (Advanced Boiling Water Reactor) plant is a new type heat exchanger to increase plant thermal efficiency. There are four single tubesheet heaters in a MSH vessel. Each heater has hundreds of low finned tubes made of ferritic stainless steel. In nuclear power plants, non-magnetic materials (austenitic stainless steel, titanium, aluminum brass, etc.,) are mainly used as heat exchanger tubes such as the tubes of feedwater heater, condenser, evaporator and so on. Conventional ECT (Eddy Current Test) method are easily applied for the inspection of these heat exchanger tubes. In recent years, the authors started using ferritic stainless steel tube for new heat exchangers such as MSH because of its superior heat transfer efficiency. However, high permeability of ferritic stainless steel prevents the inspection of these tubes using conventional ECT method. To inspect MSH tubes periodically is important to confirm and maintain reliability of MSH. They tried applying various inspection methods and have developed special ECT method for low finned ferritic stainless steel tubes

  7. High performance flexible CMOS SOI FinFETs

    KAUST Repository

    Fahad, Hossain M.

    2014-06-01

    We demonstrate the first ever CMOS compatible soft etch back based high performance flexible CMOS SOI FinFETs. The move from planar to non-planar FinFETs has enabled continued scaling down to the 14 nm technology node. This has been possible due to the reduction in off-state leakage and reduced short channel effects on account of the superior electrostatic charge control of multiple gates. At the same time, flexible electronics is an exciting expansion opportunity for next generation electronics. However, a fully integrated low-cost system will need to maintain ultra-large-scale-integration density, high performance and reliability - same as today\\'s traditional electronics. Up until recently, this field has been mainly dominated by very weak performance organic electronics enabled by low temperature processes, conducive to low melting point plastics. Now however, we show the world\\'s highest performing flexible version of 3D FinFET CMOS using a state-of-the-art CMOS compatible fabrication technique for high performance ultra-mobile consumer applications with stylish design. © 2014 IEEE.

  8. Comparison of fin-and-tube interlaced and face split evaporators with flow mal-distribution and compensation

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian

    2011-01-01

    Flow mal-distribution in fin-and tube evaporators for residential air-conditioning is investigated by numerical simulation. In particularly, the interlaced and the face split evaporator are compared in flow maldistribution conditions. The considered sources of mal-distribution are: Liquid/vapor distribution and airflow distribution. Furthermore, compensation of flow mal-distribution by control of individual channel superheat is studied for each type of evaporator. It is shown that the interlaced evaporator is better at flow maldistribution than the face split evaporator. However, if individual channel superheats are controlled, the face split evaporator achieves the best performance, i.e. an increase of 7% in UA-value and 1.6% to 2.4% in COP compared to the interlaced evaporator without compensation.

  9. Volume Averaging Theory (VAT) based modeling and closure evaluation for fin-and-tube heat exchangers

    Science.gov (United States)

    Zhou, Feng; Catton, Ivan

    2012-10-01

    A fin-and-tube heat exchanger was modeled based on Volume Averaging Theory (VAT) in such a way that the details of the original structure was replaced by their averaged counterparts, so that the VAT based governing equations can be efficiently solved for a wide range of parameters. To complete the VAT based model, proper closure is needed, which is related to a local friction factor and a heat transfer coefficient of a Representative Elementary Volume (REV). The terms in the closure expressions are complex and sometimes relating experimental data to the closure terms is difficult. In this work we use CFD to evaluate the rigorously derived closure terms over one of the selected REVs. The objective is to show how heat exchangers can be modeled as a porous media and how CFD can be used in place of a detailed, often formidable, experimental effort to obtain closure for the model.

  10. Experimental and numerical investigation of a louvered fin and elliptical tube compact heat exchanger

    Directory of Open Access Journals (Sweden)

    Pooranachandran Karthik

    2015-01-01

    Full Text Available In the present work, an experimental investigation is carried out to analyze the heat transfer characteristics of a louvered fin and elliptical tube compact heat exchanger used as a radiator in an internal combustion engine. Experiments are conducted by positioning the radiator in an open-loop wind tunnel. A total of 24 sets of air, water flow rate combinations are tested, and the temperature drops of air and water were acquired. A numerical analysis has been carried out using Fluent software (a general purpose computational fluid dynamics simulation tool for three chosen data from the experiments. The numerical air-side temperature drop is compared with those of the experimental values. A good agreement between the experimental and numerical results validates the present computational methodology.

  11. Numerical analysis of fin-tube plate heat exchanger by using CFD technique

    Directory of Open Access Journals (Sweden)

    Ahmed F. Khudheyer

    2011-07-01

    Full Text Available Three-dimensional CFD simulations are carried out to investigate heat transfer and fluid flow characteristics of a two-row plain fin-and-tube heat exchanger using Open FOAM, an open-source CFD code. Heat transfer and pressure drop characteristics of the heat exchanger are investigated for Reynolds numbers ranging from 330 to 7000. Model geometry is created, meshed, calculated, and post-processed using open source software. Fluid flow and heat transfer are simulated and results compared using both laminar and turbulent flow models (k-epsilon, and Menter SST k-omega, with steady-state solvers to calculate pressure drop, flow, and temperature fields. Model validation is carried out by comparing the simulated case friction factor f and Colburn factor j to experimental results from the literature. For friction factor determination, little difference is found between the flow models simulating laminar flow, while in transitional flow, the laminar flow model produced the most accurate results and the k-omega SST turbulence model was more accurate in turbulent flow regimes. The most accurate simulations for heat transfer in laminar flow are found using the laminar flow model, while heat transfer in transitional flow is best represented with the SST k-omega turbulence model, and heat transfer in turbulent flow is more accurately simulated with the k-epsilon turbulence model. Reasonable agreement is found between the simulations and experimental data, and the open-source software has been sufficient for simulating the flow fields in tube-fin heat exchangers.

  12. Numerical simulation and experimental verification on thermal performance of a novel fin-plate thermosyphon

    International Nuclear Information System (INIS)

    Numerical investigation of a novel fin-plate thermosyphon (FPT), used to cool the high heat dissipation electronic devices, was performed. Three dimensional model of FPT is established using the Fluent software. The effects of fin pinch, fin thickness and fin type at the air side on thermal characteristics of FPT are presented with the air flow velocity various from 1.0 m/s to 4.0 m/s. The numerical results showed a good agreement with the corresponding experimental data. The heat transfer efficiency and pressure drops of FPT for plain fins were reduced by increasing the fin space. It also can be indicated that the cooling performance of FPT with serrated fins was better than plain fins for the same structural parameters. - Highlights: ? A novel diffusion welded fin-plate thermosyphon (FPT) was designed and performed. ? The plain fins heat transfer efficiency increases with the decrease of fin spaces. ? The fin thickness is less influential on FPT performance. ? Thermal performance of serrated fins is significantly much higher than that of plain fins.

  13. Thermal behavior of crimped spiral fin tube bank under dehumidifying process: A case study of inline arrangement

    Directory of Open Access Journals (Sweden)

    Atipoang Nuntaphan

    2004-05-01

    Full Text Available Cross flow heat exchangers having crimped spiral fin and inline arrangement configurations under dehumidification are studied. The effect of tube diameter, fin spacing, fin height, transverse tube pitch are examined. From the experiment, it is found that the heat transfer and the frictional characteristics of the heat exchanger under dehumidification is close to that of the non-dehumidifying process. However, the air stream pressure drop and the heat transfer coefficient of the wet surface heat exchanger are higher and lower than those of the dry surface respectively. Moreover, equations are developed for predicting the f and the j factors of a tested heat exchanger. Results from the developed equations agree well with the experimental data.

  14. Numerical study of the pressure drop in a plain fin-and-circular tube heat exchanger under frost condition

    International Nuclear Information System (INIS)

    Full text: Three-dimensional computational fluid dynamics (CFD) simulations are carried out to study the pressure drop behavior in a plain fin-and-four staggered layout and circular tube rows for different fin pitches under frost conditions using FLUENT 6.3 CFD code. Models geometry is created and meshed using GAMBIT 2.3. Fluid flow and heat transfer are simulated and results calculated using (Transitional SST k-omega) turbulence model, with steady-state solver. Model validation is carried out by comparing the pressure drop of a simulated case with experimental results from the literature. It was found that Fluent 6.3 software has been sufficient for simulating the flow characteristics in tube-fin heat exchangers. (author)

  15. How can the heat transfer correlations for finned-tubes influence the numerical simulation of the dynamic behavior of a heat recovery steam generator?

    International Nuclear Information System (INIS)

    This paper presents the results of a theoretical investigation on the influence of different heat transfer correlations for finned-tubes to the dynamic behavior of a heat recovery steam generator (HRSG). The investigation was done for a vertical type natural circulation HRSG with 3 pressure stages under hot start-up and shutdown conditions. For the calculation of the flue gas-side heat transfer coefficient the well known correlations for segmented finned-tubes according to Schmidt, VDI and ESCOATM (traditional and revised) as well as a new correlation, which was developed at the Institute for Energy Systems and Thermodynamics, are used. The simulation results show a good agreement in the overall behavior of the boiler between the different correlations. But there are still some important differences found in the detail analysis of the boiler behavior. - Research highlights: ? Numerical simulation is performed to explore the influence of different heat transfer correlations for finned-tubes to the dynamic behavior of a heat recovery steam generator. ? Differences in the steam generator behavior are found. ? In the worst case the boiler can lead to unfavorable operation conditions, e.g. reverse flow.

  16. 3D-CFD simulation and neural network model for the j and f factors of the wavy fin-and-flat tube heat exchangers

    Scientific Electronic Library Online (English)

    M, Khoshvaght Aliabadi; M, Gholam Samani; F, Hormozi; A, Haghighi Asl.

    2011-09-01

    Full Text Available A three dimensional (3D) computational fluid dynamics (CFD) simulation and a neural network model are presented to estimate the behaviors of the Colburn factor (j) and the Fanning friction factor (f) for wavy fin - and - flat tube (WFFT) heat exchangers. Effects of the five geometrical factors of fi [...] n pitch, fin height, fin length, fin thickness, and wavy amplitude are investigated over a wide range of Reynolds number (600

  17. Non-Destructive Testing Methods Applied to Multi-Finned SAP Tubing for Nuclear-Fuel Elements

    International Nuclear Information System (INIS)

    The Danish Atomic Energy Commission has undertaken a design study oi an organic-cooled, heavy- water-moderated power reactor. The fuel element for the reactor is a 19-rod bundle; the fuel rods contain sintered uranium-dioxide pellets canned in 2-m long, helically-finned tubes of Sintered Aluminium Product (SAP). A very high quality of the canning tubes is necessary to obtain the optimum heat-transfer conditions and to maintain the integrity of the fuel element during reactor service. Two examples of tube design illustrate the narrow dimensional tolerances. In order to ensure an adequate quality of the canning tubes, a stringent quality control has been established, to a wide extent based upon non-destructive methods. An account is presented of the non-destructive techniques developed for measuring wall thickness and diameters and for detecting defects. The complex 24-finned cross-section prevents the application of ultrasonic or eddy-current methods for wall-thickness measurements. Therefore, a special recording beta-gauge has been developed, based upon the attenuation of beta radiation from a Sr90 source placed inside the tube. An ultrasonic immersion resonance method is used for the continuous recording of the wall thickness of the more simple 12-finned tube design. Inner and outer (across fin tips) diameters are continuously recorded by rapid air-gauge systems. Flaw detection is carried out by the ultrasonic pulse-echo immersion technique and by eddy-current inspection.. Transverse cracks can easily be detected by the ultrasonic method whereas inspection for longitudinal flaws has not appeared feasible with this method. Therefore, eddy-current inspection is applied in addition to the ultrasonic testing. (author)

  18. Pyramidal Fin Arrays Performance Using Streamwise Anisotropic Materials by Cold Spray Additive Manufacturing

    Science.gov (United States)

    Cormier, Yannick; Dupuis, Philippe; Jodoin, Bertrand; Corbeil, Antoine

    2015-07-01

    This work evaluates the thermal and hydrodynamic performance of pyramidal fin arrays produced using cold spray as an additive manufacturing process. Near-net-shaped pyramidal fin arrays of pure aluminum, pure nickel, and stainless steel 304 were manufactured. Fin array characterization such as fin porosity level and surface roughness evaluation was performed. The thermal conductivities of the three different coating materials were measured by laser flash analysis. The results obtained show a lower thermal efficiency for stainless steel 304, whereas the performances of the aluminum and nickel fin arrays are similar. This result is explained by looking closely at the fin and substrate roughness induced by the cold gas dynamic additive manufacturing process. The multi-material fin array sample has a better thermal efficiency than stainless steel 304. The work demonstrates the potential of the process to produce streamwise anisotropic fin arrays as well as the benefits of such arrays.

  19. Steam generator tubing NDE performance

    Energy Technology Data Exchange (ETDEWEB)

    Henry, G. [Electric Power Research Institute, Charlotte, NC (United States); Welty, C.S. Jr. [Electric Power Research Institute, Palo Alto, CA (United States)

    1997-02-01

    Steam generator (SG) non-destructive examination (NDE) is a fundamental element in the broader SG in-service inspection (ISI) process, a cornerstone in the management of PWR steam generators. Based on objective performance measures (tube leak forced outages and SG-related capacity factor loss), ISI performance has shown a continually improving trend over the years. Performance of the NDE element is a function of the fundamental capability of the technique, and the ability of the analysis portion of the process in field implementation of the technique. The technology continues to improve in several areas, e.g. system sensitivity, data collection rates, probe/coil design, and data analysis software. With these improvements comes the attendant requirement for qualification of the technique on the damage form(s) to which it will be applied, and for training and qualification of the data analysis element of the ISI process on the field implementation of the technique. The introduction of data transfer via fiber optic line allows for remote data acquisition and analysis, thus improving the efficiency of analysis for a limited pool of data analysts. This paper provides an overview of the current status of SG NDE, and identifies several important issues to be addressed.

  20. A three-dimensional numerical study and comparison between the air side model and the air/water side model of a plain fin-and-tube heat exchanger

    International Nuclear Information System (INIS)

    CFD is becoming an important heat exchanger research technique. It constitutes an inexpensive prediction method, avoiding the need of testing numerous prototypes. Current work in this field is mostly based on air flow models assuming constant temperature of fin-and-tube surface. The purpose of this paper is to present an enhanced model, whose innovation lies in considering additionally the water flow in the tubes and the conduction heat transfer through the fin and tubes, to demonstrate that the neglect of these two phenomena causes a simulation result accuracy reduction. 3-D Numerical simulations were accomplished to compare both an air side and an air/water side model. The influence of Reynolds number, fin pitch, tube diameter, fin length and fin thickness was studied. The exchanger performance was evaluated through two non-dimensional parameters: the air side Nusselt number and a friction factor. It was found that the influence of the five parameters over the mechanical and thermal efficiencies can be well reported using these non-dimensional coefficients. The results from the improved model showed more real temperature contours, with regard to those of the simplified model. Therefore, a higher accuracy of the heat transfer was achieved, yielding better predictions on the exchanger performance.

  1. Experimental investigation of forced-convection in a finned rhombic tube of the flat-plate solar collectors

    DEFF Research Database (Denmark)

    Taherian, Hessam; Yazdanshenas, Eshagh

    2006-01-01

    Due to scarcity of literature on forced-convection heat transfer in a solar collector with rhombic cross-section absorbing tubes, a series of experiments was arranged and conducted to determine heat transfer coefficient. In this study, a typical rhombic cross-section finned tube of flat-plate collectors used as the test section. Two correlations were proposed for the Nusselt number as a function of the Reynolds number and the Prandtl number based on hydraulic diameter for various heat fluxes. Th...

  2. Heat transfer and pressure loss for smoke gas in finned tube heat exchangers. Varmeovergang og tryktab for roeggas i ribberoersvarmevekslere

    Energy Technology Data Exchange (ETDEWEB)

    Krighaar, M.; Wit, J. de; Ingerslev, I.; Paulsen, O. (Energiteknologi, Dansk Teknologisk Institut (DK))

    1990-01-01

    The aim was to investigate heat transfer and pressure loss in relation to transverse flow round bunches of pipes fitted into a finned tube heat exchanger. Conditions of both condensing and non-condensing operation were dealt with. Various pipe types were examined in order to discover potentials for utilization in gas-fired boilers. Measurements were taken on ribbed pipe heat exchangers, and computer calculations were made to determine convection conditions. (AB).

  3. Geometrical optimization and mould wear effect on HPD type steel offset strip fin performance

    International Nuclear Information System (INIS)

    Aiming at studying the influence and importance of the geometrical parameters on steel HPD type offset strip fin performance, this paper reports experimental and numerical studies at low Reynolds number. A novel test rig with electrically heated single layer fin assembly as test object was constructed. Only the effects of fin height and fin wavelength on the fin characteristics were considered because of the pressing mould limitation. Through comparisons of experimental, simulated and Muzychka's results, the tendencies agree well. The deviations between them are due to the difference of fin material and the influences of the pressing mould process technique on the fins. Based on the Taguchi method and uniform design, the importance of the geometrical factors on the fin thermal-hydraulic performance was investigated. The sequence of degrees of effect for each parameter is s, h, ?, s 0, b and t. The paper obtained the optimum model and numerically proved its validity among the considered ranges. Eleven sample fins were collected during different periods of the mould life time, and the influences of mould wear on fin friction performance were examined. The mould wear includes three stages, and the performance of fins pressed during 100 thousand times to 1,050 thousand times is more stable. The recommended life time for the mould type is about 1,050 thousand times

  4. Effects of hydrophilic coating on air side heat transfer and friction characteristics of wavy fin and tube heat exchangers under dehumidifying conditions

    International Nuclear Information System (INIS)

    The air side heat transfer and friction characteristics of wavy fin and tube heat exchangers with and without hydrophilic coating are studied under dehumidifying conditions experimentally. The effects of a hydrophilic coating on air side performance are investigated. The results indicated that the influence of the hydrophilic coating on heat transfer performance is mainly related to the flow conditions of condensation water on the fin surface without hydrophilic coating. The hydrophilic coating can enhance the heat transfer performance when plenty of condensation water flows and weakens the heat transfer performance when little condensation water forms on the fin surface. The pressure drops for the hydrophilic coating surface are lower than those of the corresponding uncoated surface. A maximum 44% reduction is observed. The proposed heat transfer coefficient ratio correlation and pressure drop ratio have a mean deviation of 9.9% and 8.2% from experimental data and can predict 76.6% and 82.8% of the experimental data within the deviation limit of ±15%, respectively

  5. Effects of hydrophilic coating on air side heat transfer and friction characteristics of wavy fin and tube heat exchangers under dehumidifying conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Xiaokui; Ding, Guoliang; Zhang, Yuanming [Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030 (China); Wang, Kaijian [Fujitsu General Institute of Air Conditioning Technology Limited, 1116 Suenaga, Takatsu-Ku, Kawasaki 213-8502 (Japan)

    2007-09-15

    The air side heat transfer and friction characteristics of wavy fin and tube heat exchangers with and without hydrophilic coating are studied under dehumidifying conditions experimentally. The effects of a hydrophilic coating on air side performance are investigated. The results indicated that the influence of the hydrophilic coating on heat transfer performance is mainly related to the flow conditions of condensation water on the fin surface without hydrophilic coating. The hydrophilic coating can enhance the heat transfer performance when plenty of condensation water flows and weakens the heat transfer performance when little condensation water forms on the fin surface. The pressure drops for the hydrophilic coating surface are lower than those of the corresponding uncoated surface. A maximum 44% reduction is observed. The proposed heat transfer coefficient ratio correlation and pressure drop ratio have a mean deviation of 9.9% and 8.2% from experimental data and can predict 76.6% and 82.8% of the experimental data within the deviation limit of {+-}15%, respectively. (author)

  6. How can the heat transfer correlations for finned-tubes influence the numerical simulation of the dynamic behavior of a heat recovery steam generator?

    OpenAIRE

    Walter, H.; Hofmann, R.

    2010-01-01

    Abstract This paper presents the results of a theoretical investigation on the influ- ence of different heat transfer correlations for finned-tubes to the dynamic behavior of a heat recovery steam generator (HRSG). The investigation was done for a vertical type natural circulation HRSG with 3 pressure stages under hot start-up and shutdown conditions. For the calculation of the flue gas side heat transfer coefficient the well known correlations for segmented finned-tubes according ...

  7. Algebraic modeling and thermodynamic design of fan-supplied tube-fin evaporators running under frosting conditions

    International Nuclear Information System (INIS)

    In this study, the method of entropy generation minimization (i.e., design aimed at facilitating both heat, mass and fluid flows) is used to assess the evaporator design (aspect ratio and fin density) considering the thermodynamic losses due to heat and mass transfer, and viscous flow processes. A fully algebraic model was put forward to simulate the thermal-hydraulic behavior of tube-fin evaporator coils running under frosting conditions. The model predictions were validated against experimental data, showing a good agreement between calculated and measured counterparts. The optimization exercise has pointed out that high aspect ratio heat exchanger designs lead to lower entropy generation in cases of fixed cooling capacity and air flow rate constrained by the characteristic curve of the fan. - Highlights: • An algebraic model for frost accumulation on tube-fin heat exchangers was advanced. • Model predictions for cooling capacity and air flow rate were compared with experimental data, with errors within ±5% band. • Minimum entropy generation criterion was used to optimize the evaporator geometry. • Thermodynamic analysis led to slender designs for fixed cooling capacity and fan characteristics

  8. The impact of fin profile and interface condition on performance characteristics of heat sinks

    International Nuclear Information System (INIS)

    Thermal management of electronic products relies mainly on the effective dissipation of heat. Heat sinks (containing multiple extended surfaces or fin array) are commonly used for heat dissipation network. The performance of an individual fin depends on its geometry, material properties and operating environment (i.e. free or forced convection). In the first part of this paper, the four most commonly used fin profiles are studied for pin, longitudinal and annular fins using non-dimensional finite element formulation. In the second part, the performance of different thermal interfaces is studied for polymer and metallic fins. Polymer composite materials result in significant increase in the performance of a fin; however manufacturing can be a constraint to construct an effective heat sink due to interface conditions at the fin and base plate junction. It is found that the joint at fin base plate has considerable stress effect in the heat sink system. The press fit joint must have high contact pressure to maintain an appropriate thermal contact conductance (TCC) in order to have thermal performance comparable to an adhesive joint, but the two joints have different state of thermal and contact stresses. -- Highlights: ? The effect of fin profile on performance for pin, longitudinal and annular fins is studied. ? The significant effect is found only for pin fins under considered conditions. ? The effect of interface at orthotropic pin fin and metallic base plate is studied. ? Two interface conditions called epoxy-bonded and press-fitted are studied. ? The contact pressure and stresses decrease at high temperature for press-fitted interface

  9. Evaluación de Intercambiadores de Calor Compactos de Tubos Aletados / Evaluation of Compact Finned-Tube Heat Exchangers

    Scientific Electronic Library Online (English)

    M.T., Martínez; E., Torres; J.A., Soto.

    Full Text Available En este trabajo, se presenta el análisis térmico teórico de un intercambiador de calor compacto, con y sin condensación de agua en el lado del aire. El fenómeno de la condensación del vapor de agua en la corriente de aire entrante produce una película de agua en la superficie cubriéndola en forma pa [...] rcial o completa. El análisis considera varias configuraciones geométricas con respecto a: la superficie de las aletas y a la forma de los tubos considerando la forma circular tradicional y también un caso para tubos planos. Los resultados obtenidos reflejan la eficiencia de la aleta en ambos casos: una aleta totalmente seca (sin condensación) y a una totalmente húmeda es decir, totalmente cubierta por la película de condensado. Se concluye que la metodología propuesta es una buena alternativa de análisis y caracterización de un intercambiador, ya que los resultados obtenidos coinciden con los reportados en la literatura Abstract in english This study presents a theoretical thermal analysis of a compact heat exchanger, with and without water condensation on the air side. The phenomenon of condensation of water vapor in the entering air current produces a film of water on the surface, partially or completely covering the surface. The an [...] alysis considers various geometric configurations with respect to the surfaces of the fins and the form of the tubes, including the traditional round form as well as flattened tubes. The results obtained reflect the efficiency of the fins in both cases , including a completely dry fin (no condensation) and a completely wet fin, that is completely covered with a film of condensate. It is concluded that the methodology proposed is a good alternative for the analysis and characterization of a heat exchanger since the results agree with those reported in the literature

  10. Evaluación de Intercambiadores de Calor Compactos de Tubos Aletados Evaluation of Compact Finned-Tube Heat Exchangers

    Directory of Open Access Journals (Sweden)

    M.T. Martínez

    2004-01-01

    Full Text Available En este trabajo, se presenta el análisis térmico teórico de un intercambiador de calor compacto, con y sin condensación de agua en el lado del aire. El fenómeno de la condensación del vapor de agua en la corriente de aire entrante produce una película de agua en la superficie cubriéndola en forma parcial o completa. El análisis considera varias configuraciones geométricas con respecto a: la superficie de las aletas y a la forma de los tubos considerando la forma circular tradicional y también un caso para tubos planos. Los resultados obtenidos reflejan la eficiencia de la aleta en ambos casos: una aleta totalmente seca (sin condensación y a una totalmente húmeda es decir, totalmente cubierta por la película de condensado. Se concluye que la metodología propuesta es una buena alternativa de análisis y caracterización de un intercambiador, ya que los resultados obtenidos coinciden con los reportados en la literaturaThis study presents a theoretical thermal analysis of a compact heat exchanger, with and without water condensation on the air side. The phenomenon of condensation of water vapor in the entering air current produces a film of water on the surface, partially or completely covering the surface. The analysis considers various geometric configurations with respect to the surfaces of the fins and the form of the tubes, including the traditional round form as well as flattened tubes. The results obtained reflect the efficiency of the fins in both cases , including a completely dry fin (no condensation and a completely wet fin, that is completely covered with a film of condensate. It is concluded that the methodology proposed is a good alternative for the analysis and characterization of a heat exchanger since the results agree with those reported in the literature

  11. Thermal performance of a porus radial fin with natural convection and radiative heat losses

    Directory of Open Access Journals (Sweden)

    Darvishi M.T.

    2015-01-01

    Full Text Available An analytic (series solution is developed to describe the thermal performance of a porous radial fin with natural convection in the fluid saturating the fin and radiation heat loss from the top and bottom surfaces of the fin. The HAM results for the temperature distribution and base heat flux are compared with the direct numerical results and found to be very accurate.

  12. Alloy 800 steam generator tube performance

    International Nuclear Information System (INIS)

    This paper reviews the reasoning behind the selection of Alloy 800 nuclear grade (800NG) for tubing of steam generators in pressurized water reactor (PWR) plants designed by Siemens/Kraftwerk Union (KWU) (now AREVA) and pressurized heavy water reactor (PHWR) plants designed by Atomic Energy of Canada Limited (AECL). The PWR and PHWR plants where Alloy 800NG is used are identified. The very good operating performance of the steam generator tubes in these plants is described. The limited numbers of tubes removed from service due to indications of tube degradation in these plants are described, and the probable causes and possible future progression of the tube degradation modes involved are discussed. (author)

  13. An experimental study of the air-side particulate fouling in finned-tube heat exchangers of air conditioners through accelerated tests

    International Nuclear Information System (INIS)

    The air-side particulate fouling in the heat exchangers of HVAC applications degrades the performance of cooling capacity, pressure drop across a heat exchanger, and indoor air quality. Indoor and outdoor air contaminants foul heat exchangers. The purpose of this study is to investigate the fouling characteristics trough accelerated tests. The fouling characteristics are analyzed as functions of a dust concentration (1.28 and 3.84 g/m3), a face velocity (0.5, 1.0, and 1.5 m/s), and a surface condition. The cooling capacity in the slitted finned-tube heat exchangers at the face velocity of 1 m/s decreases about 2% and the pressure drop increases up to 57%. The rate of build-up of fouling is observed to be 3 times slower for this three-fold reduction of dust concentration whilst still approaching the same asymptotic level

  14. Analysis of Steam Condensation in a Finned Tube of Air-Water Combined Cooling System

    International Nuclear Information System (INIS)

    A Passive Auxiliary Feedwater System (PAFS) is one of the passive cooling systems of the existing power plant and the operating period is 8 hours because of the limited capacity of the cooling water tank. Therefore, to increase the operating period from 8 to 72 hours for an existing PAFS, the capacity of the cooling water tank should be increased up to 3-4 times. To resolve the excessive increase of the cooling tank volume in water cooling systems, an air-water combined passive cooling system is proposed. In this combined cooling system, the core cooling during the initial stage of an accident having high decay power depends on the water cooling systems such as PAFS. For the later phase of an accident, an air-cooling system is applied to the core cooling. In the operation of the air-cooling system, the steam from the cooling water tank of the PAFS is condensed and recirculated to the cooling water tank by an air-cooling heat exchanger. In this way, the increase of the cooling water tank volume can be minimized. To design an air-water combined cooling system, the steam condensation characteristics of an air-cooling heat exchanger tube was calculated using a CFX code. The results show that the air velocities around the tube at the steam inlet/outlet regions are quite different with each other. Therefore, dense installation of thermocouples at the tube bottom region is required to measure the steam condensation in the tube. Otherwise, the detection and measurement of steam condensation at the steam inlet region may be very difficult. The velocity distribution of air is not uniform and the distributions of air temperature and velocity around the heat exchanger tube are strongly asymmetric. In the design of the measurement system of the test facility, the problems mentioned above should be considered

  15. Experimental study of heat transfer and thermal performance with longitudinal fins of solar air heater

    Directory of Open Access Journals (Sweden)

    Foued Chabane

    2014-03-01

    Full Text Available The thermal performance of a single pass solar air heater with five fins attached was investigated experimentally. Longitudinal fins were used inferior the absorber plate to increase the heat exchange and render the flow fluid in the channel uniform. The effect of mass flow rate of air on the outlet temperature, the heat transfer in the thickness of the solar collector, and the thermal efficiency were studied. Experiments were performed for two air mass flow rates of 0.012 and 0.016 kg s?1. Moreover, the maximum efficiency values obtained for the 0.012 and 0.016 kg s?1 with and without fins were 40.02%, 51.50% and 34.92%, 43.94%, respectively. A comparison of the results of the mass flow rates by solar collector with and without fins shows a substantial enhancement in the thermal efficiency.

  16. Heat transfer and friction correlations and thermal performance analysis for a finned surface

    Energy Technology Data Exchange (ETDEWEB)

    Bilen, K. [University of Ataturk, Erzurum (Turkey). Dept. of Mechanical Engineering; Akyol, U. [University of Trakya (Turkey). Dept. of Mechanical Engineering; Yapici, S. [University of Ataturk, Erzurum (Turkey). Dept. of Chemical Engineering

    2001-07-01

    In the present work, the heat transfer and friction loss characteristics were investigated experimentally, employing a finned heating surface kept at a constant temperature of 45{sup o}C in a rectangular channel through which air was passed as a working fluid. The position of the cylindrical fins attached on the surface was arranged either in-line or staggered. The parameters for the study were chosen as Reynolds number (3700-30000), depending on hydraulic diameter, the distance between fins in the flow direction (S{sub y}/D = 1.96-4.41) and fin arrangement. The variation of Nusselt number with these parameters was determined and presented graphically. For both fin arrangements, it was found that increasing Reynolds number increased Nusselt number and friction factor were developed for both fin arrangements and smooth channel, and the thermal performances of the arrangements were also determined and compared with respect to heat transfer from the same surface without fins. With the staggered array, a heat transfer enhancement up to 33% at constant pumping power was achieved. (Author)

  17. Heat transfer and thermal performance analysis of a surface with hollow rectangular fins

    Energy Technology Data Exchange (ETDEWEB)

    Akyol, Ugur [Department of Mechanical Engineering, Faculty of Corlu Engineering, University of Trakya, 59860 Corlu/Tekirdag (Turkey); Bilen, Kadir [Department of Mechanical Engineering, Faculty of Engineering, University of Ataturk, 25240 Erzurum (Turkey)

    2006-02-01

    An experimental study was conducted to investigate the heat transfer and friction loss characteristics in a horizontal rectangular channel having attachments of hollow rectangular profile fins over one of its heated surface. The Reynolds number based on the flow averaged inlet velocity and the hydraulic diameter, ranged from 3000 to 32,000. The hollow rectangular profile fins in 10cm height and axb=2cmx4cm dimensions with a thickness of 0.2cm were mounted on a heating surface vertically. Reynolds number, fin arrangement and fin pitch in the flow direction were the experimental parameters. Both in-line and staggered fin arrangements were studied for one-fixed spanwise (S{sub x}/a=3) and four different streamwise (S{sub y}/b=1.5, 1.875, 2.5 and 3.75) distances. Correlation equations for Nu, f and thermal performances were determined for fin configurations and the straight channel case without fins. (author)

  18. Thermal performance of plate fin heat sink cooled by air slot impinging jet with different cross-sectional area

    Science.gov (United States)

    Mesalhy, O. M.; El-Sayed, Mostafa M.

    2015-06-01

    Flow and heat transfer characteristics of a plate-fin heat sink cooled by a rectangular impinging jet with different cross-sectional area were studied experimentally and numerically. The study concentrated on investigating the effect of jet width, fin numbers, and fin heights on thermal performance. Entropy generation minimization method was used to define the optimum design and operating conditions. It is found that, the jet width that minimizes entropy generation changes with heat sink height and fin numbers.

  19. Performance and cost benefits analysis of double-pass solar collector with and without fins

    International Nuclear Information System (INIS)

    Highlights: • The thermal performances and cost analysis of the double-pass solar collector with and without fins absorber were discussed. • The theoretical and experimental study on the double-pass solar air collector with and without fins absorber was conducted. • The ratio of AC/AEG or the cost benefit ratio was presented. • The double-pass solar collector with fins absorber is more cost-effective compared to without fins absorber. - Abstract: The performance and cost benefit analysis of double-pass solar collector with and without fins have been conducted. The theoretical model using steady state analysis has been developed and compared with the experimental results. The performance curves of the double-pass solar collector with and without fins, which included the effects of mass flow rate and solar intensity on the thermal efficiency of the solar collector, were obtained. Results indicated that the thermal efficiency is proportional to the solar intensity at a specific mass flow rate. The thermal efficiency increased by 9% at a solar intensity of 425–790 W/m2 and mass flow rate of 0.09 kg/s. The theoretical and experimental analysis showed a similar trend as well as close agreement. Moreover, a cost-effectiveness model has been developed examine the cost benefit ratio of double-pass solar collector with and without fins. Evaluation of the annual cost (AC) and the annual energy gain (AEG) of the collector were also performed. The results show that the double-pass solar collector with fins is more cost-effective compared to the double-pass solar collector without fins for mass flow rate of 0.01–0.07 kg/s. Also, simulations were obtained for the double-pass solar collector with fins at Nusselt number of 5.42–36.21. The energy efficiency of collector increases with the increase of Nusselt number. The results show that by increasing the Nusselt number simultaneously would drop the outlet temperature at any solar intensity. Increase in Nusselt number causes an increase in energy efficiency. On the other hand, the exergy efficiency has been obtained, which the fluctuation of exergy efficiency was based on the Nusselt number, collector length and solar intensity level

  20. Fin Field Effect Transistors Performance in Analog and RF for High-k Dielectrics

    Directory of Open Access Journals (Sweden)

    D. Nirmal

    2011-04-01

    Full Text Available The high-k is needed to replace SiO2 as the gate dielectric to reduce the gate leakage current. The impact of a high-k gate dielectric on the device short channel performance and scalability of nanoscale double gate Fin Field Effect Transistors (FinFET CMOS is examined by 2-D device simulations. DG FinFETs are designed with high-k at the high performance node of the 2008 Semiconductor Industry Association International Technology Roadmap for Semiconductors (ITRS. DG FinFET CMOS can be optimally designed to yield outstanding performance with good trade-offs between speed and power consumption as the gate length is scaled to < 10 nm. Using technology computer aided design (TCAD tools a 2-D FinFET device is created and the simulations are performed on it. The optimum value of threshold voltage is identified as VT=0.653V with e=23(ZrO2 for the 2-D device structure. For the 2-D device structure, the leakage current has been reduced to 9.47´10-14 A. High-k improves the Ion/Ioff ratio of transistors for future high-speed logic applications and also improves the storage capability.Defence Science Journal, 2011, 61(3, pp.235-240, DOI:http://dx.doi.org/10.14429/dsj.61.695

  1. Comparative Study for Improving the Thermal and Fluid Flow Performance of Micro Channel Fin Geometries Using Numerical Simulation

    Directory of Open Access Journals (Sweden)

    S.Subramanian

    2015-07-01

    Full Text Available There is a continuous quest for improving the performance of micro channels for handling the increased dissipation of heat from electronics circuits. The Oblique fin micro channels are attractive as they perform better than plate fin & pin fin configurations. There are scopes for further improvements in oblique fin micro channels. Hence this work is about the investigation for the performance enhancement by modifying the oblique fin geometry. Seven variants of micro channel geometries have been explored using three dimensional numerical simulations. The variants are plate fin, in-line pin fin, staggered pin fin, oblique fin, oblique fin with two slit angles, oblique with nozzle type slit and improved oblique fin. The simulation results are validated using the published data. To ensure a common reference for comparison, hydraulic diameter, inlet flow conditions, heat loads and the boundary conditions are kept identical across all the geometries. The results of simulation are compared for the thermal & fluid flow performances. Heat transfer correlations have been developed using the simulation data. The proposed modification is found to enhance the performance significantly

  2. Orientation effect on natural convective performance of square pin fin heat sinks

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Ren-Tsung; Sheu, Wen-Junn [Department of Power Mechanical Engineering, National Tsing Hua University, 101, Section 2, Kuang Fu Road, Hsinchu 300 (China); Wang, Chi-Chuan [Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu 310 (China)

    2008-05-15

    Experiments are carried out on natural convection heat transfer from square pin fin heat sinks subject to the influence of orientation. A flat plate and seven square pin fin heat sinks with various arrangements are tested under a controlled environment. Test results indicate that the downward facing orientation yields the lowest heat transfer coefficient. However, the heat transfer coefficients for upward and sideward facing orientations are of comparable magnitude. Depending on the fin structure, the performance of these two orientations shows a competitive nature. It is found that the sideward arrangement outperforms the upward one for small finning factors below 2.7, beyond which the situation is reversed. In addition, with the gradual increase in the finning factor, the performance of sideward arrangement approaches that of downward arrangement. Aside from the finning factor, the heat sink porosity has a secondary effect on the pin fin performance. The comparison among three orientations shifts in favour of upward and sideward arrangements with raising the heat sink porosity in consequence of reducing the flow resistance. The optimal heat sink porosity is around 83% for the upward arrangement and is around 91% for the sideward arrangement. In particular, the addition of surface is comparatively more effective for the downward arrangement whereas it is less effective for the sideward arrangement. This argument is supported by showing that the augmentation factor, defined as the heat transfer of a heat sink relative to that of a flat plate, is around 1.1-2.5 for the upward arrangement, around 0.8-1.8 for the sideward arrangement, and around 1.2-3.2 for the downward arrangement. (author)

  3. Performance comparison of pin fin in-duct flow arrays with various pin cross-sections

    Energy Technology Data Exchange (ETDEWEB)

    Sahiti, N. [LSTM-Erlangen, Institute of Fluid Mechanics, Friedrich-Alexander-University, Erlangen-Nuremberg, Cauerstr. 4, D-91058 Erlangen (Germany)]. E-mail: sahiti@lstm.uni-erlangen.de; Lemouedda, A. [Department of Process Engineering, Georg-Simon-Ohm University of Applied Sciences, Wassertorstr. 10, D-90489 Nuremberg (Germany); Stojkovic, D. [LSTM-Erlangen, Institute of Fluid Mechanics, Friedrich-Alexander-University, Erlangen-Nuremberg, Cauerstr. 4, D-91058 Erlangen (Germany); Durst, F. [LSTM-Erlangen, Institute of Fluid Mechanics, Friedrich-Alexander-University, Erlangen-Nuremberg, Cauerstr. 4, D-91058 Erlangen (Germany); Franz, E. [Department of Process Engineering, Georg-Simon-Ohm University of Applied Sciences, Wassertorstr. 10, D-90489 Nuremberg (Germany)

    2006-08-15

    Pin fin arrays are frequently used for cooling of high thermal loaded electronic components. Whereas the pin fin accomplishment regarding heat transfer is always higher than that of other fin configurations, the high pressure drop accompanying pins seriously reduces their overall performance. In order to check how the form of pin cross-section influences the pressure drop and heat transfer capabilities, six forms of pin cross-section were numerically investigated. By employing the conjugate heat transfer boundary conditions, numerical simulations close to realistic working conditions were performed. Two geometric comparison criteria were applied so that the conclusions derived from numerical computations were valid for various possible geometric parameters and working conditions. Both staggered and inline pin arrangements were investigated as these are common in practical applications. The heat transfer and pressure drop characteristics are presented in terms of appropriate dimensionless variables. The final judgment of the performance of the pin fin cross-section was performed based on the heat exchanger performance plot. Such a plot allows the assessment of the pin performance including their heat transfer and the pressure drop.

  4. Corrosion performance of tube support materials

    International Nuclear Information System (INIS)

    The problem of denting in steam generators leads to change in the conception of the tube support plates. A new material is now used for this component, a 13% Cr steel, which composition has been adjusted for weldability and mechanical resistance criteria. The geometry of trefoil support plate (TSP) has also been improved, using a broached TSP (quadrifoiled holes) instead of a drilled TSP. Tests have been performed on 13% Cr and C-steel broached TSP, and drilled TSP, to confirm the better resistance to denting of this new configuration

  5. Natural convective performance of perforated heat sinks with circular pin fins

    Science.gov (United States)

    Wen, Mao-Yu; Yeh, Cheng-Hsiung

    2015-10-01

    This study examines heat transfer performance under natural convection for two different types (Type A and Type B) of pin-fin heat sinks with/without a hollow in the heated base. The effects of the rate of heat transfer, the height of fin and base plate, the heat sink porosity and the perforated base plate on the heat-transfer coefficient and enhancement factor were investigated and evaluated. In order to obtain insight into the fluid flow phenomena, flow visualization was also made to observe the detailed fluid flow characteristics of the present pin-fin heat sinks. Experimental results show that heat transfer, using pin-fin heat sinks, is significantly different for Type A and Type B. Comparisons of the heat transfer coefficients, with respect to the unfinned base plate under the same experimental conditions, for the pin-fin heat sinks were about 1.48-fold-1.64-fold (Type A) and 1.81-fold-1.94-fold (Type B), respectively. In addition, results also show that a Type B-heat sink has a higher enhancement factor than a Type A-heat sink.

  6. Hydrodynamic Performance of an Undulatory Robot: Functional Roles of the Body and Caudal Fin Locomotion

    Directory of Open Access Journals (Sweden)

    Li Wen

    2013-01-01

    Full Text Available Both body undulation and caudal fin flapping play essential locomotive roles while a fish is swimming, but how these two affect the swimming performance and hydrodynamics of fish individually is yet to be known. We implemented a biomimetic robotic fish that travel along a servo towing system, which can be regarded as “treadmill” of the model. Hydrodynamics was studied as a function of the principal kinetic parameters of the undulatory body and caudal fin of the model in a self?propelled condition, under which the time?averaged measured axial net force becomes zero. Thrust efficiency was estimated from two?dimensional digital particle image velocimetry (DPIV measurements in the horizontal and mid?caudal fin plane. The Single?Row Reverse Karman wake (2S is commonly observed in many previous studies of live fish swimming. However, we show that a Double?Row Two?Paired vortices (2P wake was generated by the robotic model for most kinetic parameter combinations. Interestingly, the 2S wake emerged within the results of a narrow range of robotic caudal fin pitch angles (0???10°, occurring concurrently with enhanced thrust efficiency. We also show that, compared with the effect of body wavelength (?, the wake structure behind the robotic swimmer is more sensitive to the Strouhal number (St and caudal fin pitch angle (?.

  7. Effect of tube bank inclination on the thermal hydraulic performance of air-cooled heat exchangers

    International Nuclear Information System (INIS)

    This paper compares the experimental thermal hydraulic performance of an inclined tube bundle of staggered high finned tubes with that of the same bank in cross flow. The data are shown on a relative basis with the conventional cross-flow arrangement used as the reference layout. The results, presented as plots of heat transfer coefficient and pressure drop per row versus face velocity, are compared with other published data for bare and extended-surface tube banks. Correction factors that account for the deviation from cross-flow performance are presented. Estimated savings in plot area are shown for typical cases. Some possible cost reduction opportunities in specific fields of application are also suggested

  8. MODERN MANUFACTURING TECHNIQUES OF PRECISED MISSILE REAR FIN ASSEMBLY

    Directory of Open Access Journals (Sweden)

    Md Akhtar khan

    2013-11-01

    Full Text Available Missile rear fin is mainly used for direction control. The fin includes number of components likepanels, pins, tubes, lamina and caps. The performance of actuation system plays a decisive role indetermining the performance of the flight control system for a highly maneuverable missile. To controlthe missiles by aerodynamics, control surfaces, sometimes called fins, are used. The manufacturingprocess of missile fin components involves different operations like CNC turning, CNC milling,drilling, EDM, grinding, and surface treatments. The paper presents the study of manufacturingprocesses of missile rear fin assembly.

  9. The Study of Local Heat Transfer Characteristics of the Surface of a Plate Fin - Oval Tube with Delta Wing Vortex Generators

    International Nuclear Information System (INIS)

    In the present paper, the effect of Delta-Wing Vortex Generators(DWVGs) on heat transfer of the plate fin-oval tube heat exchanger was experimentally studied. The local heat transfer coefficient of the tube surface of one kind of DWVGs arrangement were measured by naphthalene sublimation technique for Reynolds numbers of 2000 ? 3200 and angles of attack of DWVG of 30 .deg. ? 60 .deg.. As the results, compared to the case without DWVGs, the heat transfer of the plate fin surface with DWVGs was enhanced from upstream to downstream in the test region. The heat transfer were significantly affected by angles of attack of DWVGs as well as Reynolds number. It showed that the result of 45 .deg. was best within test angles

  10. Performance of multi tubes in tube helically coiled as a compact heat exchanger

    Science.gov (United States)

    Nada, S. A.; El Shaer, W. G.; Huzayyin, A. S.

    2014-12-01

    Multi tubes in tube helically coiled heat exchanger is proposed as a compact heat exchanger. Effects of heat exchanger geometric parameters and fluid flow parameters; namely number of inner tubes, annulus hydraulic diameter, Reynolds numbers and input heat flux, on performance of the heat exchanger are experimentally investigated. Different coils with different numbers of inner tubes, namely 1, 3, 4 and 5 tubes, were tested. Results showed that coils with 3 inner tubes have higher values of heat transfer coefficient and compactness parameter (bar{h} Ah ). Pressure drop increases with increasing both of Reynolds number and number of inner tubes. Correlations of average Nusselt number were deduced from experimental data in terms of Reynolds number, Prandtl number, Number of inner coils tubes and coil hydraulic diameter. Correlations prediction was compared with experimental data and the comparison was fair enough.

  11. Verification of the performance of impact limiting fins for transportation containers

    International Nuclear Information System (INIS)

    Empirical data are frequently applied in designing the crush limiting fins for the special transport containers used for shipping radioactive materials. One of the most widely accepted sets of design curves was derived from research work done at Oak Ridge National Laboratories (ORNL) in 1971. This report presents the results of experimental work aimed at verifying particular aspects of the applicability of the ORNL design curves. The main objective was to check the fundamental assumption inherent in the ORNL data - namely that the design curve data can be extrapolated to any fin configuration regardless of the length and number of fins. Using a drop facility similar to ORNL, but with a modern computerized data capture system, data were collected from 625 specimens. These comprised both single and multiple fin types, that differed in height, thickness, length, angle of inclination and orientation. Included were several duplicate ORNL fin specimens for reference. Results obtained from the work reported here indicate that the basic premise regarding the extrapolation from the design curve data is reasonable. However, the results do not produce curves consistent with the ORNL curves. The newer curves of absorbed energy versus percent deformation are flatter, indicating that the percent deformation for a given energy input can sometimes vary considerably. For plots of the peak force per fin width versus height/thickness ratios the sharp upward trend for height/thickness ratios below 10 is not observed. The results obtained indicate that further work should be performed to determine the reason for the differences between the ORNL data and those data obtained from this project

  12. Experimental analysis on thermal performance of a solar air collector with longitudinal fins in a region of Biskra, Algeria

    Directory of Open Access Journals (Sweden)

    Foued Chabane

    2013-01-01

    Full Text Available This paper presents a thermal performance of a single pass solar air heater with fins attached was investigated experimentally. Longitudinal fins were used inferior the absorber plate for an increase the heat exchange and uniform the flow fluid in the channel. The effects of mass flow rate of air on the outlet temperature, the heat transfer in a thickness of solar collector and thermal efficiency were studied. Experiments were performed for two air mass flow rates of 0.012 kg/s., Moreover; the maximum efficiency was obtained by using five longitudinal fins and without fins. The maximum efficiency obtained for the 0.012 kg/s with and without fins were 40.02 % and 34.92 %, respectively. Comparison of the results as an effect the solar collector’s with and without fins shows a substantial enhancement in the thermal efficiency.

  13. Design and performance of a straw tube drift chamber

    Science.gov (United States)

    Oh, S. H.; Wesson, D. K.; Cooke, J.; Goshaw, A. T.; Robertson, W. J.; Walker, W. D.

    1991-06-01

    The design and performance of the straw drift chambers used in E735 is reported. The chambers are constructed from 2.5 cm radius aluminized mylar straw tubes with wall thickness less than 0.2 mm. Also, presented are the results of tests with 2 mm radius straw tubes. The small tube has a direct detector application at the Superconducting Super Collider.

  14. Parametric study of the swimming performance of a fish robot propelled by a flexible caudal fin

    Energy Technology Data Exchange (ETDEWEB)

    Low, K H; Chong, C W, E-mail: mkhlow@ntu.edu.s, E-mail: ch0018ee@ntu.edu.s [School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2010-12-15

    In this paper, we aim to study the swimming performance of fish robots by using a statistical approach. A fish robot employing a carangiform swimming mode had been used as an experimental platform for the performance study. The experiments conducted aim to investigate the effect of various design parameters on the thrust capability of the fish robot with a flexible caudal fin. The controllable parameters associated with the fin include frequency, amplitude of oscillation, aspect ratio and the rigidity of the caudal fin. The significance of these parameters was determined in the first set of experiments by using a statistical approach. A more detailed parametric experimental study was then conducted with only those significant parameters. As a result, the parametric study could be completed with a reduced number of experiments and time spent. With the obtained experimental result, we were able to understand the relationship between various parameters and a possible adjustment of parameters to obtain a higher thrust. The proposed statistical method for experimentation provides an objective and thorough analysis of the effects of individual or combinations of parameters on the swimming performance. Such an efficient experimental design helps to optimize the process and determine factors that influence variability.

  15. Parametric study of the swimming performance of a fish robot propelled by a flexible caudal fin

    International Nuclear Information System (INIS)

    In this paper, we aim to study the swimming performance of fish robots by using a statistical approach. A fish robot employing a carangiform swimming mode had been used as an experimental platform for the performance study. The experiments conducted aim to investigate the effect of various design parameters on the thrust capability of the fish robot with a flexible caudal fin. The controllable parameters associated with the fin include frequency, amplitude of oscillation, aspect ratio and the rigidity of the caudal fin. The significance of these parameters was determined in the first set of experiments by using a statistical approach. A more detailed parametric experimental study was then conducted with only those significant parameters. As a result, the parametric study could be completed with a reduced number of experiments and time spent. With the obtained experimental result, we were able to understand the relationship between various parameters and a possible adjustment of parameters to obtain a higher thrust. The proposed statistical method for experimentation provides an objective and thorough analysis of the effects of individual or combinations of parameters on the swimming performance. Such an efficient experimental design helps to optimize the process and determine factors that influence variability.

  16. Performance of a tapered pulse tube

    International Nuclear Information System (INIS)

    In a well instrumented pulse tube refrigerator having 1,500 W of cooling power at 125 K, the authors have measured the figure of merit of a tapered pulse tube at several operating points. At operating points near the operating point for which the taper was designed, the figure of merit is 0.96. This is close to the theoretical optimum figure of merit 0.97 calculated for this pulse tube considering only two loss mechanisms: heat conduction in the metal pulse tube wall and ordinary thermoacoustic heat transport in the gas within a few thermal penetration depths of the wall. At operating points farther from the design operating point, the measured figure of merit is much lower, as streaming driven convection adds a third loss mechanism

  17. A novel 1D/2D model for simulating conjugate heat transfer applied to flow boiling in tubes with external fins

    Science.gov (United States)

    Oc?o?, Pawe?; ?opata, Stanis?aw; Nowak, Marzena

    2015-04-01

    This study presents a novel, simplified model for the time-efficient simulation of transient conjugate heat transfer in round tubes. The flow domain and the tube wall are modeled in 1D and 2D, respectively and empirical correlations are used to model the flow domain in 1D. The model is particularly useful when dealing with complex physics, such as flow boiling, which is the main focus of this study. The tube wall is assumed to have external fins. The flow is vertical upwards. Note that straightforward computational fluid dynamics (CFD) analysis of conjugate heat transfer in a system of tubes, leads to 3D modeling of fluid and solid domains. Because correlation is used and dimensionality reduced, the model is numerically more stable and computationally more time-efficient compared to the CFD approach. The benefit of the proposed approach is that it can be applied to large systems of tubes as encountered in many practical applications. The modeled equations are discretized in space using the finite volume method, with central differencing for the heat conduction equation in the solid domain, and upwind differencing of the convective term of the enthalpy transport equation in the flow domain. An explicit time discretization with forward differencing was applied to the enthalpy transport equation in the fluid domain. The conduction equation in the solid domain was time discretized using the Crank-Nicholson scheme. The model is applied in different boundary conditions and the predicted boiling patterns and temperature fields are discussed.

  18. Design and performance of a straw tube drift chamber

    International Nuclear Information System (INIS)

    The design and performance of the straw drift chambers used in E735 is reported. The chambers are constructed from 2.5 cm radius aluminized mylar straw tubes with wall thickness less than 0.2 mm. Also, presented are the results of tests with 2 mm radius straw tubes. The small tube has a direct detector application at the Superconducting Super Collider. (orig.)

  19. Numerical analysis for the air-side convective heat transfer characteristics in a compact heat exchanger with flat tubes and plate fins according to the aspect ratio

    Energy Technology Data Exchange (ETDEWEB)

    Moh, Jeong Hah [Wonkwang Univ., Iksan (Korea, Republic of)

    2008-09-15

    Numerical analysis has been carried out to investigate air-side convective heat transfer characteristics in a compact heat exchanger with flat tubes and continuous plate fins according to the aspect ratio. RNG k-{epsilon} model is applied for turbulence analysis. Simulation results such as air velocity and temperature distributions are presented, and heat transfer coefficients are compared with previous correlations for circular tubes. The numerical conditions are considered for the aspect ratios ranging from 3.06 to 5.44 and Reynolds number ranging from 1000 to 10,000. The results showed that heat transfer coefficients decreased with the increase of aspect ratio. From the calculated results a correlation of Colburn j factor for the considered aspect ratio in the compact heat exchanger system is suggested. The predicted results in this study can be applied to the optimal design of air conditioning system.

  20. Evacuated-tube solar collector--performance evaluation

    Science.gov (United States)

    1980-01-01

    Report gives thermal performance test procedures and results for commercially produced, water-filled, 8-tube collectors. Tests include efficiency, time constant for temperature drop after solar flux is cut, change in efficiency as function of sun angle, and test to see if tubes break when filled with hot water.

  1. Windsurfer Fin

    Science.gov (United States)

    1994-01-01

    A NASA report detailing a wind tunnel investigation of a variable camber and twist could effectively reduce drag, thus improving performance. The resulting VooDoo fin is made of composite materials, has a rigid internal spar and a flexible polymer exterior coating. It is computer-designed and exceptionally durable.

  2. Thermal performance of plate-fin heat exchanger using passive techniques: vortex-generator and nanofluid

    Science.gov (United States)

    Khoshvaght-Aliabadi, Morteza

    2015-06-01

    This experimental study investigates the effects of vortex-generator (VG) and Cu/water nanofluid flow on performance of plate-fin heat exchangers. The Cu/water nanofluids are produced by using a one-step method, namely electro-exploded wire technique, with four nanoparticles weight fractions (i.e. 0.1, 0.2, 0.3, and 0.4 %). Required properties of nanofluids are systematically measured, and empirical correlations are developed. A highly precise test loop is fabricated to obtain accurate results of the heat transfer and pressure drop characteristics. Experiments are conducted for nanofluids flow inside the plain and VG channels. Based on the experimental results, utilizing the VG channel instead of the plain channel enhances the heat transfer rate, remarkably. Also, the results show that the VG channel is more effective than the nanofluid on the performance of plate-fin heat exchangers. It is observed that the combination of the two heat transfer enhancement techniques has a noticeably high thermal-hydraulic performance, about 1.67. Finally, correlations are developed to predict Nusselt number and friction factor of nanofluids flow inside the VG channel.

  3. Mechanical actuator for biomimetic propulsion and the effect of the caudal fin elasticity on the swimming performance

    OpenAIRE

    Apalkov, Andrey; Fernández, Roemi; Fontaine, Jean-Guy; Akinfiev, Teodor; Armada Rodríguez, Manuel Ángel

    2012-01-01

    This paper presents a mechanical actuator for the biomimetic propulsion of swimming devices and the experimental study of the effect of the caudal fin elasticity on the overall performance. The design of the proposed drive allows the DC motor to operate at constant speed, so all the power of the motor is spent only for the motion of the caudal fin. A prototype of the actuator, in which the caudal fin serves as a driving element, is manufactured and tested in both laboratory and natural condit...

  4. Leak and burst tests performed on pulled tubes

    International Nuclear Information System (INIS)

    The plugging criteria for tubes used in France for PWR plant steam generator tubes allow the presence of through wall cracks during operation. Calculations and tests show the cracks remain stable under accidental conditions and feedback shows that they do not generally result in large leaks. Tests performed on pulled tubes confirm the safety margins provided by the plugging criteria selected with respect to the risks of leakage and sudden propagation of corrosion cracks under accidental conditions. This paper proposes a method for roughly estimating the leakage rate under accidental conditions for a steam generator with corrosion at the top of the tubesheet or at the tube support plate elevation, which is based on tests performed exclusively on pulled tubes and the results of on-site inspections. (authors). 3 figs., 2 tabs., 7 refs

  5. Studying the performance of solid/perforated pin-fin heat sinks using entropy generation minimization

    Science.gov (United States)

    Elsayed, Mohamed L.; Mesalhy, Osama

    2015-05-01

    Heat transfer and pressure drop characteristics of a set of pin-fins with uniform heat flux were investigated experimentally and numerically. Test set-up was designed to assess the effects of mass flow rate, fin height, and fin density on convection heat transfer and pressure drop. In the numerical investigation, the flow field of various design parameters of the heat sink was simulated. It was found that heat sinks having fin heights of 20 and 30 mm operated at a lower Reynolds number reached minimum value for thermal resistance when the fin density 10 × 10. Which means it is the optimum number of fins for this case. Also, friction factor increased with a decrease in the bypass flow area or inter-fin distance spacing and using perforated fins reduced the pressure losses and thermal resistance for all studied cases.

  6. Advanced microchannel heat exchanger with S-shaped fins

    International Nuclear Information System (INIS)

    Fin shape effects on thermal-hydraulic characteristics were studied for a Microchannel Heat Exchanger (MCHE) with S-shaped fins using 3D-CFD and changing the fin parameters: fin angle, overlapping length, fin width, fin length, and edge roundness. The fin angle effect on the pressure drop is consistent with the equation obtained experimentally by Weisbach for a circular bent tube: the pressure drop in the S-shaped fin configuration results from bent flow. The overlap of fins with those located immediately downstream at the offset position provides a guide wing effect that reduces the pressure drop remarkably. The overlap was changed by changing the fin radial position and arc length. The pressure drop was minimized when the downstream fins are placed in the middle of the bent flow channels formed by the fins upstream, which differs from Ito's configuration obtained from experiments with a single bent duct. Regarding arc length, the pressure drop is minimized at the standard overlapping length, which was formed to have the longest arc without a change in channel width. Shorter arc lengths from the optimum value by 30 and 50%, respectively, give 2.4 and 4.6% decreases in the heat transfer rate and 17 and 13% increases in the pressure drop. Thinner fins show better thermal-hydraulic performance for fin widths of 0.2-0.8 mm. However, the pressure drop reduced by the longer fin and heat transfer rate was also reduced. Rounded fins with 0.1 mm radius increased the pressure drop by about 30% compared with that of the fin designed with no roundness. (author)

  7. WWER Steam Generators Tubing Performance and Aging Management

    International Nuclear Information System (INIS)

    At WWER NPPs the horizontal steam generators (SGs), are used that differ in design concept from vertical SGs mostly used at western NPPs. Reliable operation of SG heat-exchanging tubes is the crucial worldwide problem for NPP of various types. According to the operation feedback the water chemistry is the governing factor affecting operability of SG tubing. The secondary side corrosion is considered to be the main mechanism of SG heat-exchanging tubes damage at WWER plants. To make the assessment of the tubing integrity the combination of pressure tests and eddy-current tests is used. Assessment of the tubing performance is an important part of SG life extension practice. The given paper deals with the description of the tube testing strategy and the approach to tube integrity assessment based on deterministic and probabilistic methods of fracture mechanics. Requirements for eddy-current test are given as well. Practice of condition monitoring and implementing the database on steam generators operation are presented. The approach to tubes plugging criteria is described. The research activities on corrosion mechanism studies and residual lifetime evaluation are mentioned. (authors)

  8. Numerical Analysis for the Air-Side Convective Heat Transfer Characteristics in a Compact Heat Exchanger with Circular Tubes and Continuous Plate Fins

    International Nuclear Information System (INIS)

    Numerical analysis has been carried out to investigate air-side convective heat transfer characteristics in a compact heat exchanger with circular tubes and continuous plate fins. Simulation results such as air velocity and temperature distributions are presented, and heat transfer coefficients are compared with previous experimental correlations. Three models of standard and RNG k-?, and Reynolds stress are applied for turbulence model applicability. Predicted heat transfer coefficient from the models of standard and RNG k-? are very close to those of the heat transfer correlations while there are relatively large difference, more than 17 percentage in the result from the Reynolds stress model. From the calculated results a correlation for Colburn j factor in the compact heat exchanger system is suggested

  9. Numerical Analysis for the Air-Side Convective Heat Transfer Characteristics in a Compact Heat Exchanger with Circular Tubes and Continuous Plate Fins

    Energy Technology Data Exchange (ETDEWEB)

    Moh, Jeong Hah; Lee, Sang Ho [Wonkwang Univ., Iksan (Korea, Republic of)

    2007-12-15

    Numerical analysis has been carried out to investigate air-side convective heat transfer characteristics in a compact heat exchanger with circular tubes and continuous plate fins. Simulation results such as air velocity and temperature distributions are presented, and heat transfer coefficients are compared with previous experimental correlations. Three models of standard and RNG k-{epsilon}, and Reynolds stress are applied for turbulence model applicability. Predicted heat transfer coefficient from the models of standard and RNG k-{epsilon} are very close to those of the heat transfer correlations while there are relatively large difference, more than 17 percentage in the result from the Reynolds stress model. From the calculated results a correlation for Colburn j factor in the compact heat exchanger system is suggested.

  10. Numeric Simulation on the Performance of an Undulating Fin in the Wake of a Periodic Oscillating Plate

    Directory of Open Access Journals (Sweden)

    Zhang Yong-Hua

    2013-10-01

    Full Text Available A two-dimensional unsteady computational fluid dynamics (CFD method using an unstructured, grid-based and unsteady Navier-Stokes solver with automatic adaptive re-meshing to compute the unsteady flow was adopted to study the hydrodynamic interaction between a periodic oscillating plate and a rigid undulating fin in tandem arrangement. The user-defined function (UDF program was compiled to define the undulating and oscillating motion. First, the influence of the distance between the anterior oscillating plate and the posterior undulating fin on the non-dimensional drag coefficient of the fin was investigated. Ten different distances, D=0.2L, 0.4L, 0.6L, 0.8L, 1.0L, 1.2L, 1.4L, 1.6L, 1.8L and 2.0L, were considered. The performance of the fin for different distances (D is different. Second, the plate oscillating angle (5.7o, 10 o, 20 o, 30 o, 40 o, 45 o, 50 o and frequency (0.5 Hz, 1.0 Hz, 1.5 Hz, 2.0 Hz, 2.5 Hz, 3.0 Hz, 3.5 Hz, 4.0 Hz effects on the non-dimensional drag coefficient of the fin were also implemented. The pressure distribution on the fin was computed and integrated to provide fin forces, which were decomposed into lift and thrust. Meanwhile, the flow field was demonstrated and analysed. Based on the flow structures, the reasons for different undulating performances were discussed. It shows that the results largely depend on the distance between the two objects. The plate oscillating angle and frequency also make a certain contribution to the performance of the posterior undulating fin. The results are similar to the interaction between two undulating objects in tandem arrangement and they may provide a physical insight into the understanding of fin interaction in fishes or bio-robotic underwater propulsors that are propelled by multi fins.

  11. Finned heat exchanger. Ib. General and basic aspects

    International Nuclear Information System (INIS)

    This paper is a review of the main literature studies about the finned heat exchanger modelling and simulation. Finned heat exchangers are used in cryogenic industry, nuclear industry, food industry, medicine, etc.. The aspects concerning the air circulation through the heat exchanger component tubes are studied, as well as those involved in the thermal transfer from technological fluid to wall or from fin to air. A particular attention is devoted to the physical and mathematical complete models of finned heat exchangers, as well as to the criterial relationship for the calculation of the partial heat transfer to air (?2), fin efficiency (?a) and friction coefficient (f). Details are also given about the influence of the thermal contact resistance on the finned heat exchanger performance. This study is a useful tool for a correct technological sizing of this type of heat exchangers. (authors)

  12. Finned heat exchangers. Ia. General and basic aspects

    International Nuclear Information System (INIS)

    This paper is a review of the main literature studies about the finned heat exchanger modelling and simulation. Finned heat exchangers are used in cryogenic industry, nuclear industry, food industry, medicine, etc. The aspects concerning the air circulation through the heat exchanger component tubes are studied, as well as those involved in the thermal transfer from technological fluid to wall or from fin to air. A particular attention is devoted to the physical and mathematical complete models of finned heat exchangers, as well as to the criterial relationship for the calculation of the partial thermal transfer to air, ?2, fin efficiency, ?a and friction coefficient, f. Details are also given about the influence of the thermal contact resistance on the finned heat exchanger performance. This study is a useful tool for a correct technological sizing of this heat exchanger type. (authors)

  13. Thermal and friction drop characteristic of heat exchangers with elliptical tubes and smooth fins / Caracterización térmica e hidráulica de intercambiadores de calor con tubos elípticos y aletas lisas

    Scientific Electronic Library Online (English)

    Rubén, Borrajo-Pérez; Jurandir, Ititzo Yanagihara; Juan José, González-Bayón.

    2012-12-01

    Full Text Available Caída de presión y transferencia de calor son importantes parámetros en intercambiadores de calor. Existe falta de información cuando de intercambiadores de calor y tubos elípticos se trata. El objetivo del trabajo fue caracterizar experimentalmente modelos de intercambiadores de calor con tubos elí [...] pticos y aletas lisas. El numero de Reynolds y los espaciamientos fueron variados, dentro del régimen laminar. Los experimentos fueron desarrollados en un túnel de viento de circuito abierto usando la sublimación de naftaleno y la analogía calor y masa. Los números de Nusselt medio, locales y el factor de fricción fueron obtenidos en forma de correlaciones de Factores de Fricción y Colburn. Las correlaciones, validas para 200 Abstract in english Pressure drop and heat transfer are the most important parameters in compact heat exchanger. There is a lack of information in the literature about heat exchanger with elliptical tube. The objective of this work was the experimental characterization of compact heat exchangers models using elliptical [...] tube with eccentricity of 0,5 and smooth fins. The Reynolds numbers and the spacing were varied and always inside laminar regime. The experiments were conducted in an open wind tunnel using sublimation of naphthalene and the heat and mass transfer analogy. As results, the average and local Nusselt number and friction factor for 36 models were obtained. Correlations for Colburn and friction factors were presented. This correlations were obtained for 200

  14. In-reactor performance of pressure tubes in CANDU reactors

    Science.gov (United States)

    Rodgers, D. K.; Coleman, C. E.; Griffiths, M.; Bickel, G. A.; Theaker, J. R.; Muir, I.; Bahurmuz, A. A.; Lawrence, S. St.; Resta Levi, M.

    2008-12-01

    The pressure tubes in CANDU reactors have been operating for times up to about 25 years. The in-reactor performance of Zr-2.5Nb pressure tubes has been evaluated by sampling and periodic inspection. This paper describes the behaviour and discusses the factors controlling the behaviour of these components in currently operating CANDU reactors. The mechanical properties (such as ultimate tensile strength, UTS, and fracture toughness), and delayed-hydride-cracking properties (crack growth rate Vc, and threshold stress intensity factor, KIH) change with irradiation; the former reach a limiting value at a fluence of <1 × 10 25 n m -2, while Vc and KIH reach a steady-state condition after a fluence of about 3 × 10 25 n m -2 and 3 × 10 24 n m -2, respectively. At saturation the UTS is raised by about 200 MPa, toughness is reduced to about 40% of its initial value, Vc increases by about a factor of ten while KIH is only slightly reduced. The role of microstructure and trace elements in these behaviours is described. Pressure tubes exhibit elongation and diametral expansion. The deformation behaviour is a function of operating conditions and material properties that vary from tube-to-tube and as a function of axial location. Semi-empirical predictive models have been developed to describe the deformation response of average tubes as a function of operating conditions. For corrosion and, more importantly deuterium pickup, semi-empirical predictive models have also been developed to represent the behaviour of an average tube. The effect of material variability on corrosion behaviour is less well defined compared with other properties. Improvements in manufacturing have increased fracture resistance by minimising trace elements, especially H and Cl, and reduced variability by tightening controls on forming parameters, especially hot-working temperatures.

  15. Performance of double –pass solar collector with CPC and fins for heat transfer enhancement

    International Nuclear Information System (INIS)

    The temperature of photovoltaic modules increases when it absorbs solar radiation, causing a decrease in efficiency. This undesirable effect can be partially avoided by applying a heat recovery unit with fluid circulation (air or water) with the photovoltaic module. Such unit is called photovoltaic / thermal collector (pv/t) or hybrid (pv/t). In this unit, photovoltaic cells were pasted directly on the flat plate absorber. An experimental study of a solar air heater with photovoltaic cell located at the absorber with fins and compound parabolic collector for heat transfer enhancement and increasing the number of reflection on the cells have been conducted. The performance of the photovoltaic, thermal, and combined pv/t collector over range of operating conditions and the results was discussed. Results at solar irradiance of 500 W/m2 show that the combined pv/t efficiency is increasing from 37.28 % to 81.41 % at mass flow rates various from 0.029 to 0.436 kg/s.

  16. Thermal/hydraulic design and performance of an LMFBR double wall tube seven tube steam generator model

    International Nuclear Information System (INIS)

    This paper describes the thermal/hydraulic design and performance of a full-length LMFBR steam generator. This seven-tube model (the few tube model-FTM), uses straight, prestressed double wall tubes with third fluid leak detection capabilities. This paper describes the FTM design and instrumentation, the test facility including digital data acquisition system, and a comparison between pretest predictions and actual experimental thermal/hydraulic performance results for 100 percent load. 7 refs

  17. An approximate analytical prediction about thermal performance and optimum design of pin fins subject to condensation of saturated steam flowing under forced convection

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, B.; Ghosh, G.K. [Department of Mechanical Engineering, Jadavpur University, Jadavpur, Kolkata 700 032, West Bengal (India)

    2009-08-15

    An approximate analytical method has been suggested for solving the governing equation for horizontal pin fins subject to condensation while saturated steam flowing over its under laminar forced convection. Adomian decomposition method is used for determination of the temperature distribution, performance and optimum dimensions of pin fins with temperature dependent thermal conductivity under the condensation of steam on the fin surface. From the results, a significant effect on the temperature distribution in the fin and its performances are noticed with the variation in fin-geometric parameters and thermo-physical properties of saturated vapor. Next, a generalized scheme for optimization has been demonstrated in such a way that either heat-transfer duty or fin volume can be taken as a constraint. Finally, the curves for the optimum design have been generated for the variation of different thermo-physical and geometric parameters, which may be helpful to a designer for selecting an appropriate design condition. (author)

  18. Experimental study of thermal–hydraulic performance of cam-shaped tube bundle with staggered arrangement

    International Nuclear Information System (INIS)

    Highlights: • Thermal–hydraulic performance of a non-circular tube bundle has been investigated experimentally. • Tubes were mounted in staggered arrangement with two longitudinal pitch ratios 1.5 and 2. • Drag coefficient and Nusselt number of tubes in second row was measured. • Friction factor of this tube bundle is lower than circular tube bundle. • Thermal–hydraulic performance of this tube bundle is greater than circular tube bundle. - Abstract: Flow and heat transfer from cam-shaped tube bank in staggered arrangement is studied experimentally. Tubes were located in test section of an open loop wind tunnel with two longitudinal pitch ratios 1.5 and 2. Reynolds number varies in range of 27,000 ? ReD ? 42,500 and tubes surface temperature is between 78 and 85 °C. Results show that both drag coefficient and Nusselt number depends on position of tube in tube bank and Reynolds number. Tubes in the first column have maximum value of drag coefficient, while its Nusselt number is minimum compared to other tubes in tube bank. Moreover, pressure drop from this tube bank is about 92–93% lower than circular tube bank and as a result thermal–hydraulic performance of this tube bank is about 6 times greater than circular tube bank

  19. Thermal performance in circular tube fitted with coiled square wires

    International Nuclear Information System (INIS)

    The effects of wires with square cross section forming a coil used as a turbulator on the heat transfer and turbulent flow friction characteristics in a uniform heat flux, circular tube are experimentally investigated in the present work. The experiments are performed for flows with Reynolds numbers ranging from 5000 to 25,000. Two different spring coiled wire pitches are introduced. The results are also compared with those obtained from using a typical coiled circular wire, apart from the smooth tube. The experimental results reveal that the use of coiled square wire turbulators leads to a considerable increase in heat transfer and friction loss over those of a smooth wall tube. The Nusselt number increases with the rise of Reynolds number and the reduction of pitch for both circular and square wire coils. The coiled square wire provides higher heat transfer than the circular one under the same conditions. Also, performance evaluation criteria to assess the real benefits in using both coil wires of the enhanced tube are determined

  20. Predicting optimum vortex tube performance using a simplified CFD model

    International Nuclear Information System (INIS)

    The Ranque-Hilsch tube is a particular type of vortex tube device. The flow enters the device tangentially near one end and exits from the open ends of the tube. The inlet air is of a uniform temperature throughout while the outputs are of different temperatures. One outlet is hotter and the other is colder than the inlet air. This device has no moving parts and does not require any additional power for its operation other than that supplied to the device to compress the inlet air. It has, however, not been widely used, mainly because of its low efficiency. In this paper, a simplified 2-dimensional computational fluid dynamics model for the flow in the vortex tube is developed using FLUENT. This model makes use of the assumption of axial symmetry throughout the entire flow domain. Compared to a three-dimensional computational solution, the simplified model requires significantly less computational time. This is important because the model is to be used for an optimization study. A user-defined function is generated to implement a modified version of the k-epsilon model to account for turbulence. This model is validated by comparing a particular solution with available experimental data. The variation of cold temperature drop and efficiency of the device with orifice diameter, inlet pressure and cold mass flow ratio qualitatively agree with experimental results. Variation of these performance indices with tube length did not agree with the experiments for small values of tube length. However, it did agree qualitatively for large values. (author)

  1. A Comparative Study of Conventional and Tip-Fin Propeller Performance

    DEFF Research Database (Denmark)

    Andersen, Poul

    1997-01-01

    During more than a decade several attempts have been made to obtain higher propeller efficiencies by radically modifying the geometry in the tip region of the blade. In the tip-fin propeller a tip fin or winglet is attached to the blade tip and integrated into the blade in such a way that the blade tip is softly curved towards the suction side.Whereas the developments previously have been concentrated mainly on increasing the efficiency of the propeller, the emphasis of current efforts has been on both high efficiency as well as good cavitation properties. This has resulted in a design with a combination of skew and tip fin. To evaluate the design, open-water, self-propulsion and cavitation model tests have been carried out. The tests are done for the conventional propeller originally designed for the ship and for a tip-fin propeller designed for the same ship under the same operation conditions.The results of the model tests show higher open-water efficiency of the tip-fin propeller as well as higher over-all propulsive efficency. Depending on the method used in the full-scale extrapolation this corresponds to reduction in propulsive power of 3.7 to 4.7 per cent. Both propellers suffer from slight wake field behind the ship. The tip-fin propeller suffered a little more from cavitation than the conventional propeller which gave rise to maximum, measured, first-order pressure pulses of 1.3 to 1.4 times those of the conventional propeller.

  2. Performance of the CMS Drift Tube Chambers with Cosmic Rays

    CERN Document Server

    Chatrchyan, S; Sirunyan, A M; Adam, W; Arnold, B; Bergauer, H; Bergauer, T; Dragicevic, M; Eichberger, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kastner, K; Krammer, M; Liko, D; Magrans de Abril, I; Mikulec, I; Mittermayr, F; Neuherz, B; Oberegger, M; Padrta, M; Pernicka, M; Rohringer, H; Schmid, S; Schöfbeck, R; Schreiner, T; Stark, R; Steininger, H; Strauss, J; Taurok, A; Teischinger, F; Themel, T; Uhl, D; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C E; Chekhovsky, V; Dvornikov, O; Emeliantchik, I; Litomin, A; Makarenko, V; Marfin, I; Mossolov, V; Shumeiko, N; Solin, A; Stefanovitch, R; Suarez Gonzalez, J; Tikhonov, A; Fedorov, A; Karneyeu, A; Korzhik, M; Panov, V; Zuyeuski, R; Kuchinsky, P; Beaumont, W; Benucci, L; Cardaci, M; De Wolf, E A; Delmeire, E; Druzhkin, D; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Adler, V; Beauceron, S; Blyweert, S; D'Hondt, J; De Weirdt, S; Devroede, O; Heyninck, J; Kalogeropoulos, A; Maes, J; Maes, M; Mozer, M U; Tavernier, S; Van Doninck, W; Van Mulders, P; Villella, I; Bouhali, O; Chabert, E C; Charaf, O; Clerbaux, B; De Lentdecker, G; Dero, V; Elgammal, S; Gay, A P R; Hammad, G H; Marage, P E; Rugovac, S; Vander Velde, C; Vanlaer, P; Wickens, J; Grunewald, M; Klein, B; Marinov, A; Ryckbosch, D; Thyssen, F; Tytgat, M; Vanelderen, L; Verwilligen, P; Basegmez, S; Bruno, G; Caudron, J; Delaere, C; Demin, P; Favart, D; Giammanco, A; Grégoire, G; Lemaitre, V; Militaru, O; Ovyn, S; Piotrzkowski, K; Quertenmont, L; Schul, N; Beliy, N; Daubie, E; Alves, G A; Pol, M E; Souza, M H G; Carvalho, W; De Jesus Damiao, D; De Oliveira Martins, C; Fonseca De Souza, S; Mundim, L; Oguri, V; Santoro, A; Silva Do Amaral, S M; Sznajder, A; Fernandez Perez Tomei, T R; Ferreira Dias, M A; Gregores, E M; Novaes, S F; Abadjiev, K; Anguelov, T; Damgov, J; Darmenov, N; Dimitrov, L; Genchev, V; Iaydjiev, P; Piperov, S; Stoykova, S; Sultanov, G; Trayanov, R; Vankov, I; Dimitrov, A; Dyulendarova, M; Kozhuharov, V; Litov, L; Marinova, E; Mateev, M; Pavlov, B; Petkov, P; Toteva, Z; Chen, G M; Chen, H S; Guan, W; Jiang, C H; Liang, D; Liu, B; Meng, X; Tao, J; Wang, J; Wang, Z; Xue, Z; Zhang, Z; Ban, Y; Cai, J; Ge, Y; Guo, S; Hu, Z; Mao, Y; Qian, S J; Teng, H; Zhu, B; Avila, C; Baquero Ruiz, M; Carrillo Montoya, C A; Gomez, A; Gomez Moreno, B; Ocampo Rios, A A; Osorio Oliveros, A F; Reyes Romero, D; Sanabria, J C; Godinovic, N; Lelas, K; Plestina, R; Polic, D; Puljak, I; Antunovic, Z; Dzelalija, M; Brigljevic, V; Duric, S; Kadija, K; Morovic, S; Fereos, R; Galanti, M; Mousa, J; Papadakis, A; Ptochos, F; Razis, P A; Tsiakkouri, D; Zinonos, Z; Hektor, A; Kadastik, M; Kannike, K; Müntel, M; Raidal, M; Rebane, L; Anttila, E; Czellar, S; Härkönen, J; Heikkinen, A; Karimäki, V; Kinnunen, R; Klem, J; Kortelainen, M J; Lampén, T; Lassila-Perini, K; Lehti, S; Lindén, T; Luukka, P; Mäenpää, T; Nysten, J; Tuominen, E; Tuominiemi, J; Ungaro, D; Wendland, L; Banzuzi, K; Korpela, A; Tuuva, T; Nedelec, P; Sillou, D; Besancon, M; Chipaux, R; Dejardin, M; Denegri, D; Descamps, J; Fabbro, B; Faure, J L; Ferri, F; Ganjour, S; Gentit, F X; Givernaud, A; Gras, P; Hamel de Monchenault, G; Jarry, P; Lemaire, M C; Locci, E; Malcles, J; Marionneau, M; Millischer, L; Rander, J; Rosowsky, A; Rousseau, D; Titov, M; Verrecchia, P; Baffioni, S; Bianchini, L; Bluj, M; Busson, P; Charlot, C; Dobrzynski, L; Granier de Cassagnac, R; Haguenauer, M; Miné, P; Paganini, P; Sirois, Y; Thiebaux, C; Zabi, A; Agram, J L; Besson, A; Bloch, D; Bodin, D; Brom, J M; Conte, E; Drouhin, F; Fontaine, J C; Gelé, D; Goerlach, U; Gross, L; Juillot, P; Le Bihan, A C; Patois, Y; Speck, J; Van Hove, P; Baty, C; Bedjidian, M; Blaha, J; Boudoul, G; Brun, H; Chanon, N; Chierici, R; Contardo, D; Depasse, P; Dupasquier, T; El Mamouni, H; Fassi, F; Fay, J; Gascon, S; Ille, B; Kurca, T; Le Grand, T; Lethuillier, M; Lumb, N; Mirabito, L; Perries, S; Vander Donckt, M; Verdier, P; Djaoshvili, N; Roinishvili, N; Roinishvili, V; Amaglobeli, N; Adolphi, R; Anagnostou, G; Brauer, R; Braunschweig, W; Edelhoff, M; Esser, H; Feld, L; Karpinski, W; Khomich, A; Klein, K; Mohr, N; Ostaptchouk, A; Pandoulas, D; Pierschel, G; Raupach, F; Schael, S; Schultz von Dratzig, A; Schwering, G; Sprenger, D; Thomas, M; Weber, M; Wittmer, B; Wlochal, M; Actis, O; Altenhöfer, G; Bender, W; Biallass, P; Erdmann, M; Fetchenhauer, G; Frangenheim, J; Hebbeker, T; Hilgers, G; Hinzmann, A; Hoepfner, K; Hof, C; Kirsch, M; Klimkovich, T; Kreuzer, P; Lanske, D; Merschmeyer, M; Meyer, A; Philipps, B; Pieta, H; Reithler, H; Schmitz, S A; Sonnenschein, L; Sowa, M; Steggemann, J; Szczesny, H; Teyssier, D; Zeidler, C; Bontenackels, M; Davids, M; Duda, M; Flügge, G

    2010-01-01

    Studies of the performance of the CMS drift tube barrel muon system are described, with results based on data collected during the CMS Cosmic Run at Four Tesla. For most of these data, the solenoidal magnet was operated with a central field of 3.8 T. The analysis of data from 246 out of a total of 250 chambers indicates a very good muon reconstruction capability, with a coordinate resolution for a single hit of about 260 microns, and a nearly 100% efficiency for the drift tube cells. The resolution of the track direction measured in the bending plane is about 1.8 mrad, and the efficiency to reconstruct a segment in a single chamber is higher than 99%. The CMS simulation of cosmic rays reproduces well the performance of the barrel muon detector.

  3. Performance analysis of double basin solar still with evacuated tubes

    International Nuclear Information System (INIS)

    Solar still is a very simple device, which is used for solar distillation process. In this research work, double basin solar still is made from locally available materials. Double basin solar still is made in such a way that, outer basin is exposed to sun and lower side of inner basin is directly connected with evacuated tubes to increase distillate output and reducing heat losses of a solar still. The overall size of the lower basin is about 1006 mm x 325 mm x 380 mm, the outer basin is about 1006 mm x 536 mm x 100 mm Black granite gravel is used to increase distillate output by reducing quantity of brackish or saline water in the both basins. Several experiments have conducted to determine the performance of a solar still in climate conditions of Mehsana (latitude of 23 degree 59' and longitude of 72 degree 38'), Gujarat, like a double basin solar still alone, double basin solar still with different size black granite gravel, double basin solar still with evacuated tubes and double basin solar still with evacuated tubes and different size black granite gravel. Experimental results show that, connecting evacuated tubes with the lower side of the inner basin increases daily distillate output of 56% and is increased by 60%, 63% and 67% with average 10 mm, 20 mm and 30 mm size black granite gravel. Economic analysis of present double basin solar still is 195 days. (authors)

  4. Complicações em lipoaspiração clássica para fins estéticos Complications of classical liposuction performed for cosmetic purposes

    Directory of Open Access Journals (Sweden)

    Fernando Fabrício Franco

    2012-03-01

    Full Text Available A lipoaspiração realizada para procedimentos estéticos tem como objetivo a retirada de gordura em pacientes saudáveis e redução do acúmulo de gordura localizada, a chamada lipodistrofia, levando à melhora no contorno corporal. Nas últimas três décadas, a lipoaspiração vem sendo aperfeiçoada; porém, como qualquer outro procedimento cirúrgico, não é isenta de complicações. O objetivo deste estudo é realizar revisão da bibliografia, por meio do PubMed, identificando as complicações após lipoaspiração clássica, incluindo apenas aquelas realizadas com finalidade estética. Foram encontrados 210 artigos empregando a expressão "complication in liposuction", 86 artigos com "complication after liposuction", 27 artigos com "fat embolism after liposuction", 7 artigos com "fat embolism following liposuction" e 16 artigos com "deaths related to liposuction". Dentre esses artigos, apenas 84 foram considerados relacionados ao assunto, sendo encontrados casos de embolia gordurosa após lipoaspiração, perfuração visceral, lesão vascular, cegueira e infecção por herpes zoster, entre outros relatos. Com base nos artigos analisados foi possível concluir que a lipoaspiração é um procedimento altamente eficaz quando bem indicado e bem realizado, porém existem riscos inerentes ao ato cirúrgico. Este levantamento constatou que existem muitos artigos abordando complicações após lipoaspiração para fins estéticos, e a embolia gordurosa pulmonar apresenta alta incidência.Liposuction for esthetic purposes aims to remove fat in healthy patients and reduce localized fat accumulation, called lipodystrophy, in order to improve body contour. In the last 3 decades, the liposuction technique has improved dramatically. However, like any other surgical procedure, it is not without complications. Here, we reviewed the literature on PubMed to identify complications after classic liposuction performed solely for esthetic purposes. In total, 210 articles were found using the term "complication in liposuction," 86 with "complication after liposuction," 27 with "fat embolism after liposuction," 7 with "fat embolism following liposuction," and 16 with "deaths related to liposuction." Among these articles, only 84 including cases of fat embolism after liposuction, visceral perforation, vascular injury, blindness, and herpes zoster infection among others were considered to be related to the subject. Based on the analyzed articles, we can conclude that liposuction is a highly effective procedure when well indicated and performed accurately. Despite this, there are inherent risks. This review found many articles addressing complications, predominantly pulmonary fat embolism, after liposuction for esthetic purposes.

  5. Complicações em lipoaspiração clássica para fins estéticos / Complications of classical liposuction performed for cosmetic purposes

    Scientific Electronic Library Online (English)

    Fernando Fabrício, Franco; Rafael de Campos Ferreira, Basso; Alfio José, Tincani; Paulo, Kharmandayan.

    2012-03-01

    Full Text Available A lipoaspiração realizada para procedimentos estéticos tem como objetivo a retirada de gordura em pacientes saudáveis e redução do acúmulo de gordura localizada, a chamada lipodistrofia, levando à melhora no contorno corporal. Nas últimas três décadas, a lipoaspiração vem sendo aperfeiçoada; porém, [...] como qualquer outro procedimento cirúrgico, não é isenta de complicações. O objetivo deste estudo é realizar revisão da bibliografia, por meio do PubMed, identificando as complicações após lipoaspiração clássica, incluindo apenas aquelas realizadas com finalidade estética. Foram encontrados 210 artigos empregando a expressão "complication in liposuction", 86 artigos com "complication after liposuction", 27 artigos com "fat embolism after liposuction", 7 artigos com "fat embolism following liposuction" e 16 artigos com "deaths related to liposuction". Dentre esses artigos, apenas 84 foram considerados relacionados ao assunto, sendo encontrados casos de embolia gordurosa após lipoaspiração, perfuração visceral, lesão vascular, cegueira e infecção por herpes zoster, entre outros relatos. Com base nos artigos analisados foi possível concluir que a lipoaspiração é um procedimento altamente eficaz quando bem indicado e bem realizado, porém existem riscos inerentes ao ato cirúrgico. Este levantamento constatou que existem muitos artigos abordando complicações após lipoaspiração para fins estéticos, e a embolia gordurosa pulmonar apresenta alta incidência. Abstract in english Liposuction for esthetic purposes aims to remove fat in healthy patients and reduce localized fat accumulation, called lipodystrophy, in order to improve body contour. In the last 3 decades, the liposuction technique has improved dramatically. However, like any other surgical procedure, it is not wi [...] thout complications. Here, we reviewed the literature on PubMed to identify complications after classic liposuction performed solely for esthetic purposes. In total, 210 articles were found using the term "complication in liposuction," 86 with "complication after liposuction," 27 with "fat embolism after liposuction," 7 with "fat embolism following liposuction," and 16 with "deaths related to liposuction." Among these articles, only 84 including cases of fat embolism after liposuction, visceral perforation, vascular injury, blindness, and herpes zoster infection among others were considered to be related to the subject. Based on the analyzed articles, we can conclude that liposuction is a highly effective procedure when well indicated and performed accurately. Despite this, there are inherent risks. This review found many articles addressing complications, predominantly pulmonary fat embolism, after liposuction for esthetic purposes.

  6. Experimental study and numerical simulation of flow and heat transfer performance on an offset plate-fin heat exchanger

    Science.gov (United States)

    Du, Juan; Qian, Zuo-Qin; Dai, Zhong-yuan

    2015-10-01

    An experimental investigation of heat transfer and pressure drop characteristics of an offset plate-fin heat exchanger for cooling of lubricant oil is conducted. The empirical correlations for j-factor and f-factor are obtained by evaluating the experimental data with a modified Wilson plot method. A numerical simulation is performed and the comparison between numerical results and experimental data are presented and discussed. The results show that the simulation results are consistent with experimental data.

  7. Development and performance of a double diaphragm shock tube

    International Nuclear Information System (INIS)

    After recalling the techniques used to produce intense shocks in gases, the double diaphragm shock tube (T.C.D.2), studied and developed at the Vaujours Research Center, is presented. The theoretical and experimental performances were compared, argon being used as the test gas. In this way, it was shown that shock waves having velocities as high as 15 km/s could be produced. Various diagnostic techniques were employed to measure the velocity of the wave front and its attenuation, as well as the thickness of the gas heated by the shock (expressed generally by the test time, ?, at a given point). An estimation of the temperature and electron number density of the plasma behind the shock was effected spectroscopically. The experimental results obtained confirm theoretical predictions. It is shown that the velocity gain of T.C.D.2 over a simple shock tube may be as high as 60 per cent. (author)

  8. Performance of a lead radiator, gas tube calorimeter

    International Nuclear Information System (INIS)

    Design and performance of a 4.2 radiation length lead-sandwich, gas tube hodoscope are discussed. The device, measuring 1 /times/ 2 m2 in area and 12 cm in depth, was employed in Fermi National Accelerator Laboratory experiment 705. Multiple samplings of anode wires situated within three-walled aluminum tubes were used to generate an X coordinate; similarly, capacitively coupled copper-clad strips were ganged together to yield a Y coordinate. The results reviewed are based on an analysis of electron calibration data taken during a recent six-month running period. In particular, position resolution (in millimeters) is seen to be 0.8 + 3.3/?E + 31/E for the 9.92 mm spaced wires and 0.6 + 3.2/?E + 32/E for the 12.5 mm strips, where E represents the electron beam energy in GeV. 5 refs., 6 figs

  9. Modeling the discontinuous individual channel injection into fin-and-tube evaporators for residential air-conditioning

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian

    2012-01-01

    In this paper a working principle based upon the novel expansion and distributor device EcoFlowTM is analyzed. The device enables compensation of flow maldistribution by control of individual channel superheat. The working principle is discontinuous liquid injection (pulsating flow) into each individual channels during a specified cycle time. Moreover, the influence of the injection cycle time is investigated together with an optional secondary flow into the other channels with regards to cooling capacity, overall UA-value and COP. The results showed spurious fluctuations in pressure when simulating the pulsating flow, thus the dynamic behavior in the mixture two-phase flow model is insufficient to model the discontinuous liquid injection principle. Despite, the fluctuations and imperfections of the model we found that the cycle time should be kept as low as possible and that the optional secondary flow increases performance. Moreover, the paper reports on the applicability of Modelica developed models to analyze and optimize the working principle and design of expansion devices such that Modelica may be used in future development of novel discontinuous expansion devices.

  10. Performance evaluation of a natural-convection solar air-heater with a rectangular-finned absorber plate

    Energy Technology Data Exchange (ETDEWEB)

    Fakoor Pakdaman, M.; Lashkari, A.; Basirat Tabrizi, H.; Hosseini, R. [Department of Mechanical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2011-02-15

    This paper deals with an experimental investigation to evaluate different thermal characteristics of a natural-convection flat-plate solar air-heater with longitudinal rectangular fins array. Having determined the thermal performance of the system a Nusselt number correlation is presented for such finned duct devices. In the presented empirical model which may have industrial applications, solar radiation and ambient temperature have been considered as independent parameters. Other characteristics of the system such as different dimensionless variables, plates and outflow temperatures, efficiency, and mass flow rate have been empirically modeled based on these variables. The particular difference in this study in comparison with the other similar studies is the presentation of an empirical model for rectangular-finned solar air-heaters. This model proposes design concepts and rules of thumb, and demonstrates the calculations of the design parameters. Based on the order of magnitude analysis, solar radiation has been found to be the main parameter which characterizes the thermal behavior of the system. Besides, exergy analysis has been carried out, and optimum conditions in which the system has the highest performance have been determined. (author)

  11. Performance evaluation of a natural-convection solar air-heater with a rectangular-finned absorber plate

    International Nuclear Information System (INIS)

    This paper deals with an experimental investigation to evaluate different thermal characteristics of a natural-convection flat-plate solar air-heater with longitudinal rectangular fins array. Having determined the thermal performance of the system a Nusselt number correlation is presented for such finned duct devices. In the presented empirical model which may have industrial applications, solar radiation and ambient temperature have been considered as independent parameters. Other characteristics of the system such as different dimensionless variables, plates and outflow temperatures, efficiency, and mass flow rate have been empirically modeled based on these variables. The particular difference in this study in comparison with the other similar studies is the presentation of an empirical model for rectangular-finned solar air-heaters. This model proposes design concepts and rules of thumb, and demonstrates the calculations of the design parameters. Based on the order of magnitude analysis, solar radiation has been found to be the main parameter which characterizes the thermal behavior of the system. Besides, exergy analysis has been carried out, and optimum conditions in which the system has the highest performance have been determined.

  12. COMPARISON OF TEMPORAL PARAMETERS OF SWIMMING RESCUE ELEMENTS WHEN PERFORMED USING DOLPHIN AND FLUTTER KICK WITH FINS - DIDACTICAL APPROACH

    Directory of Open Access Journals (Sweden)

    Marek Rejman

    2012-12-01

    Full Text Available The aim of this study was an analysis of the time required to swim to a victim and tow them back to shore, while perfoming the flutter-kick and the dolphin-kick using fins. It has been hypothesized that using fins while using the dolphin-kick when swimming leads to reduced rescue time. Sixteen lifeguards took part in the study. The main tasks performed by them, were to approach and tow (double armpit a dummy a distance of 50m while applying either the flutter-kick, or the dolphin-kick with fins. The analysis of the temporal parameters of both techniques of kicking demonstrates that, during the approach to the victim, neither the dolphin (tmean = 32.9s or the flutter kick (tmean = 33.0s were significantly faster than the other. However, when used for towing a victim the flutter kick (tmean = 47.1s was significantly faster when compared to the dolphin-kick (tmean = 52.8s. An assessment of the level of technical skills in competitive swimming, and in approaching and towing the victim, were also conducted. Towing time was significantly correlated with the parameter that linked the temporal and technical dimensions of towing and swimming (difference between flutter kick towing time and dolphin-kick towing time, 100m medley time and the four swimming strokes evaluation. No similar interdependency has been discovered in flutter kick towing time. These findings suggest that the dolphin-kick is a more difficult skill to perform when towing the victim than the flutter-kick. Since the hypothesis stated was not confirmed, postulates were formulated on how to improve dolphin-kick technique with fins, in order to reduce swimming rescue time

  13. Performance of 2mm radius straw tube drift cells

    International Nuclear Information System (INIS)

    The performance of a 128 channel test module made with straw tubes of 2mm radius has been studied in a test beam and with cosmic rays. Different gases were used and for each one the time-to-distance relation and the hit efficiency was measured. Comparison are made between results when two different electronics readouts were used. The information was recorded with 106 MHz FADC units and also with TDCs (50ps resolution). The best resolution, of 135 ?m, was obtained using 50% ethane, 50% argon and reading out the information with the TDCs, at an operating HV of 1,750V

  14. Felipe Neto em performance no YouTube: uma responsabilidade mútua entre performer e audiências

    Directory of Open Access Journals (Sweden)

    Tiago Barcelos Pereira Salgado

    2012-12-01

    Full Text Available This paper aims at understanding to what extent Felipe Netos performance on his video Desabafo e coisas da madrugada published on YouTube explicits a responsibility between performer and audiences. We understand performance as a relacional practice that is performed for different audiences that are called together to participate therein. We also emphasize the espetacular and entertained dimension of Netos performance on web.

  15. Thermal Performance of Convective-Radiative Heat Transfer in Porous Fins

    Directory of Open Access Journals (Sweden)

    Majid SHAHBABAEI

    2014-01-01

    Full Text Available Forced and natural convection in porous fins with convective coefficient at the tips under radiation and convection effects are investigated in this paper. Aluminum and copper as fin materials are investigated. In forced and natural convection, air and water are applied as working fluids, respectively. In order to solve this nonlinear equation, Homotopy Perturbation Method (HPM and Variational Iteration Method (VIM are used. To verify the accuracy of the methods, a comparison is made to the exact solution (BVP. In this work, the effects of porosity parameter (, Radiation parameter (? and Temperature-Ratio parameter (µ on non-dimensional temperature distribution for both of the flows are shown. The results show that the effects of (? and (µ on temperature distribution in natural convection are based on porosity and in forced convection are uniform, approximately. Also, it is shown that both VIM and HPM are capable of being used to solve this nonlinear heat transfer equation.doi:10.14456/WJST.2014.64

  16. Steam generator tube performance. Experience with water-cooled nuclear power reactors during 1985

    International Nuclear Information System (INIS)

    The performance of steam generator tubes at water-cooled reactors during 1985 has been reviewed. Seventy-three of 168 reactors in the survey experienced tube degradation sufficient for the tubes to be plugged. The number of tubes plugged was 6837 or 0.28% of those in service. The leading cause of tube failure was stress corrosion cracking from the primary side. Stress corrosion cracking or intergranular attack from the secondary side and pitting were also major causes of tube failure. Unlike most previous years, fretting was a substantial problem at some reactors. Overall, corrosion continued to account for more than 80% of the defects. 20 refs

  17. Effects of intraspecific variation in reproductive traits, pectoral fin use and burst swimming on metabolic rates and swimming performance in the Trinidadian guppy (Poecilia reticulata)

    DEFF Research Database (Denmark)

    Svendsen, Jon Christian; Banet, Amanda I.

    2013-01-01

    There is considerable intraspecific variation in metabolic rates and locomotor performance in aquatic ectothermic vertebrates; however, the mechanistic basis remains poorly understood. Using pregnant Trinidadian guppies (Poecilia reticulata), a livebearing teleost, we examined the effects of reproductive traits, pectoral fin use and burse-assisted swimming on swimming metabolic rate, standard metabolic rate (MO2std) and prolonged swimming performance (Ucrit). Reproductive traits included reproductive allocation and pregnancy stage, the former defined as the mass of the reproductive tissues divided by the total body mass. Results showed that the metabolic rate increased curvilinearly with swimming speed. The slope of the relationship was used as an index of swimming cost. There was no evidence that reproductive traits correlated with swimming cost, MO2std or Ucrit. In contrast, data revealed strong effects of pectoral fin use on swimming cost and Ucrit. Poecilia reticulata employed body-caudal fin (BCF) swimming at all tested swimming speeds; however, fish with a high simultaneous use of the pectoral fins exhibited increased swimming cost and decreased Ucrit. These data indicated that combining BCF swimming and pectoral fin movement over a wide speed range, presumably to support swimming stability and control, is an inefficient swimming behaviour. Finally, transition to burst-assisted swimming was associated with an increase in aerobic metabolic rate. Our study highlights factors other than swimming speed that affect swimming cost and suggests that intraspecific diversity in biomechanical performance, such as pectoral fin use, is an important source of variation in both locomotor cost and maximal performance.

  18. Experimental analysis on frosting characteristic of SK-type finned refrigerating heat exchanger with large-diameter circular holes

    International Nuclear Information System (INIS)

    This paper presents the construction of both a plane fin-and-tube heat exchanger and a SK-type fin-and-tube heat exchanger. Based on plane fin-and-tube heat exchanger, comparative industrial prototype experiments of SK-type fin-and-tube heat exchanger energy efficiency performance were carried out in the artificial climate chamber. Test results confirmed several findings: when the amount of the refrigerant charged is the same and face velocity u = 3.75 m s?1, SK-type fin-and-tube heat exchanger refrigeration capacity increases by an average of 9.13%; energy consumption reduces by an average of 11.25%, coefficient of performance (COP) of heat exchanger increases by an average of 22.65% with continuous operation during the first 2 h. Also, when the operation time exceeds 2 h, the COP of both types of heat exchangers are both less than 0.6, illustrating that under frost conditions, the defrost interval should not be too long, otherwise energy consumption may sharply spike. - Highlights: •The large holes of SK-type induced the generation of turbulence flow. •The refrigeration capacity and COP of SK-type exceeds that of plane one. •The SK-type fin-and-tube heat exchanger is a new kind of heat transfer equipment. •The defrost interval should not exceed 2 h under frost conditions

  19. Fluid-structure interaction numerical simulation of thermal performance and mechanical property on plate-fins heat exchanger

    Science.gov (United States)

    Zhang, Lingjie; Qian, Zuoqin; Deng, Jun; Yin, Yuting

    2015-09-01

    A numerical simulation and experimental study of heat transfer, fluid flow and fins mechanical property on plate-fin heat exchanger has been presented in this paper. The methods used in this study are experiment, CFD analysis, fluid-structure interaction and finite element method. An air-oil wind tunnel is established for this experiment. The temperature difference, pressure drop, streamlines are obtained in overall model, and the heat transfer coefficient, j/ f factor, temperature and stress distribution of plate-fin body are obtained in different fin thickness and fin offset. The prediction from the CFD simulation shows reasonably good agreement with the experimental results.

  20. Effect of gravity opientation on the thermal performance of Stirling-type pulse tube cryocoolers

    Science.gov (United States)

    Ronald, Ross G., Jr.; Johnson, D. L.

    2003-01-01

    This paper extends the investigation of angular orientation effects to the refrigeration performance of high frequency (-40 Hz) Stirling-type pulse tube cryocoolers typical of those used in long-life space applications. Strong orientation effects on the performance of such cryocoolers have recently been observed during system-level testing of both linear and U-tube type pulse tubes. To quantify the angular dependency effects, data have been gathered on both U-tube and linear type pulse tubes of two different manufacturers as a function of orientation angle, cold-tip temperature, and compressor stroke.

  1. The Impact of Uncertainties Associated with Regenerator Hydrodynamic Closure Parameters on the Performance of Inertance Tube Pulse Tube Cryocoolers

    Science.gov (United States)

    Cha, J. S.; Ghiaasiaan, S. M.; Kirkconnell, C. S.; Clearman, W. M.

    2008-03-01

    Recent investigations have shown that CFD techniques can be applied for modeling the entire pulse tube (PTC) cryocooler systems. However, the results of CFD simulations can be trusted only if they are based on correct closure relations. The hydrodynamic and heat transfer parameters associated with regenerators are among the most important closure relations for these cryocooler systems. In this investigation the impact of uncertainties associated with oscillatory and steady flow resistance parameters on the performance of Inertance Tube Pulse Tube Cryocoolers (ITPTC) is examined using CFD simulations. This objective is achieved by simulations where reference or baseline ITPTCs systems operating in near steady-periodic conditions are modeled in their entirety. Ten transient simulations is performed using oscillatory and steady flow hydrodynamic closure relations corresponding to some of the most widely used regenerator fillers. The effects of uncertainties in the regenerator closure parameters on the cryocoolers performance parameters, as well as their key local hydrodynamic transport processes, are thus quantified.

  2. High-rate performance of muon drift tube detectors

    International Nuclear Information System (INIS)

    The Large Hadron Collider (LHC) at the European Centre for Particle Physics, CERN, collides protons with an unprecedentedly high centre-of-mass energy and luminosity. The collision products are recorded and analysed by four big experiments, one of which is the ATLAS detector. In parallel with the first LHC run from 2009 to 2012, which culminated in the discovery of the last missing particle of the Standard Model of particle physics, the Higgs boson, planning of upgrades of the LHC for higher instantaneous luminosities (HL-LHC) is already progressing. The high instantaneous luminosity of the LHC puts high demands on the detectors with respect to radiation hardness and rate capability which are further increased with the luminosity upgrade. In this thesis, the limitations of the Muon Drift Tube (MDT) chambers of the ATLAS Muon Spectrometer at the high background counting rates at the LHC and performance of new small diameter muon drift tube (sMDT) detectors at the even higher background rates at HL-LHC are studied. The resolution and efficiency of sMDT chambers at high ?-ray and proton irradiation rates well beyond the ones expected at HL-LHC have been measured and the irradiation effects understood using detailed simulations. The sMDT chambers offer an about an order of magnitude better rate capability and are an ideal replacement for the MDT chambers because of compatibility of services and read-out. The limitations of the sMDT chambers are now in the read-out electronics, taken from the MDT chambers, to which improvements for even higher rate capability are proposed.

  3. Environment-friendly heat exchangers. CO2 applications and tubes with internal finning for glycol air coolers; Umweltfreundliche Waermetauscher. CO{sub 2}-Anwendungen und innen geriffelte Rohre fuer Glykol-Luftkuehler

    Energy Technology Data Exchange (ETDEWEB)

    Filippini, S. [LU-VE CONTARDO S.p.A., Uboldo-Varese (Italy)

    2006-07-01

    The contribution discusses two different aspects: 1. The use of tubes with internal finning for glycol air coolers. These special tubes have a higher internal HI even with very low REynolds numbers (1800 + 3000) without internal pressure loss. This makes for a new line of highly efficient glycol air coolers. 2. Identification of key parameters for the design of efficient CO2 heat exchangers. An air cooler analysis shows that simple battery reforming provides good results at higher pressure levels in spite of different CO2 characteristics. Gas coolers, on the other hand, necessitate a new design for higher pressure resistance and optimum utilisation of CO2 properties. Correct operation necessitates special mechanical solutions for the material and ocmponents. A new method of heat exchanger design was developed. In order to ensure high gas cooler efficiency especially in the summer season, LU-VE developed innovative designs for spraying of the battery surface with demineralized water. (orig.)

  4. Steam generator tube performance: experience with water-cooled nuclear power reactors during 1979

    International Nuclear Information System (INIS)

    The performance of steam generator tubes in water-cooled nuclear power reactors has been reviewed for 1979. Tube failures occurred at 38 of the 93 reactors surveyed. Causes of these failures and procedures designed to deal with them are described. The defect rate was twice that in 1978 but still lower than the two previous years. Methods being employed to detect defects include increasing use of multifrequency eddy-current testing and a trend to full-length inspection of all tubes. To reduce the incidence of tube failures by corrosion, plant operators are turning to full-flow condensate demineralization and more leak-resistant condenser tubes. (author)

  5. Subcooled boiling heat transfer on a finned surface

    International Nuclear Information System (INIS)

    Experimental and numerical studies have been performed to determine the heat transfer coefficients from a finned cylindrical surface to subcooled boiling water. The heat transfer rates were measured in an annular test section consisting of an electrically heated fuel element simulator (FES) with eight longitudinal, rectangular fins enclosed in a glass tube. A two-dimensional finite-element heat transfer model using the Galerkin method was employed to determine the heat transfer coefficients along the periphery of the FES surface. An empirical correlation was developed to predict the heat transfer coefficients during subcooled boiling. The correlation agrees well with the measured data. (6 figures) (Author)

  6. Effects of intraspecific variation in reproductive traits, pectoral fin use and burst swimming on metabolic rates and swimming performance in the Trinidadian guppy (Poecilia reticulata).

    Science.gov (United States)

    Svendsen, Jon C; Banet, Amanda I; Christensen, Rune H B; Steffensen, John F; Aarestrup, Kim

    2013-09-15

    There is considerable intraspecific variation in metabolic rates and locomotor performance in aquatic ectothermic vertebrates; however, the mechanistic basis remains poorly understood. Using pregnant Trinidadian guppies (Poecilia reticulata), a live-bearing teleost, we examined the effects of reproductive traits, pectoral fin use and burst-assisted swimming on swimming metabolic rate, standard metabolic rate (O2std) and prolonged swimming performance (Ucrit). Reproductive traits included reproductive allocation and pregnancy stage, the former defined as the mass of the reproductive tissues divided by the total body mass. Results showed that the metabolic rate increased curvilinearly with swimming speed. The slope of the relationship was used as an index of swimming cost. There was no evidence that reproductive traits correlated with swimming cost, O2std or Ucrit. In contrast, data revealed strong effects of pectoral fin use on swimming cost and Ucrit. Poecilia reticulata employed body-caudal fin (BCF) swimming at all tested swimming speeds; however, fish with a high simultaneous use of the pectoral fins exhibited increased swimming cost and decreased Ucrit. These data indicated that combining BCF swimming and pectoral fin movement over a wide speed range, presumably to support swimming stability and control, is an inefficient swimming behaviour. Finally, transition to burst-assisted swimming was associated with an increase in aerobic metabolic rate. Our study highlights factors other than swimming speed that affect swimming cost and suggests that intraspecific diversity in biomechanical performance, such as pectoral fin use, is an important source of variation in both locomotor cost and maximal performance. PMID:23737561

  7. Dorsal fin anatomy (Cetacean dorsal fin Anatomy)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Cetacean dorsal fin Anatomy for ONR. Comparison within populations to ascertain phenotypic differences. Findings corroborate field observation. dorsal fin description

  8. Steam generator tube performance: experience with water-cooled nuclear power reactors during 1983 and 1984

    International Nuclear Information System (INIS)

    A review of the performance of steam generator tubes in water-cooled nuclear power reactors showed that tubes were plugged at 47 (35.6%) of the reactors in 1983 and at 63 (42.6%) of the reactors during 1984. In 1983 and 1984 3291 and 3335 tubes, respectively, were removed from service, about the same as in 1982. The leading causes assigned to tube failure were stress corrosion cracking from the primary side and stress corrosion cracking or intergranular attack from the secondary side. In addition 5668 tubes were repaired for further service by installation of internal sleeves. Most of these were believed to have deteriorated by one of the above mechanisms or by pitting. There is a continuing trend towards high-integrity condenser tube materials at sites cooled by brackish or sea water. 31 refs

  9. Coiled tubing gaining respect : once considered headed for extinction, coiled tubing's focus on performance is paying dividends

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.

    2003-03-01

    Coiled tubing was introduced to the oil and gas industry about 20 years ago, at which time it was plagued with reliability problems, failures and costly repairs. Today, the technology is outpacing conventional pipe technology due to advances in metallurgy and improved manufacturing processes. Over the years, coiled tubing has expanded its uses and has moved into harsher environments, and the issue of reliability has been better addressed than in the early years. Tests are commonly performed to analyze the fatigue life of ultra-high-pressure coiled tubing springs to improve the reliability of the coiled tubing in the field. Advanced predictive fatigue algorithms measure the lifespan of each individual strings and consider factors such as cumulative fatigue from cyclical stress, internal pressures exerted on the pipe, reel dimensions and pipe grade and size. The CYCLE string fatigue management software has essentially eliminated fatigue-caused failures. The software program takes into account the effects of corrosive fluids, types of welds and repairs, along with maintenance, storage and operations history. Corrosion damage is still the industry's biggest challenge, topping the list of causes for premature pipe failing. Computer models are constantly being developed to approach the challenging issues from all sides. 3 figs.

  10. Study of the thermal performance of external and internal finned plate-heat exchangers for nuclear steam generator application

    International Nuclear Information System (INIS)

    The present study points out two main categories of steam generators for nuclear plants with PWR reactor, on one side of the Babcok and Wilcox type, and on the other side of the Westinghouse type. The present study examines, from a recent patent, the possibility to add internal and external fins in the steam generator exchangers of PWR reactors. The finned-plate heat exchanger is first described. The thermal characteristics of a finned-plate and of an exchanger including these plates are tested. The theoretical study and the experiment are both presented. The study deals more particularly with the evaluation of the global heat exchange coefficient that the internal fins allow to improve. The experiment has been carried out for different flow rates and at different temperatures

  11. Experimental performance of single and double pass solar air heater with fins and steel wire mesh as absorber

    Energy Technology Data Exchange (ETDEWEB)

    Omojaro, A.P.; Aldabbagh, L.B.Y. [Mechanical Engineering Dept., Eastern Mediterranean University, Gazimagusa, Mersin 10 (Turkey)

    2010-12-15

    Thermal performance of a single and double pass solar air heater with fins attached and using a steel wire mesh as absorber plate was investigated experimentally. The effects of air mass flow rate range between 0.012 kg/s and 0.038 kg/s on the outlet temperature and thermal efficiency was studied. The bed heights were 7 cm and 3 cm for the lower and upper channels respectively. Result shows that, the efficiency increase with increasing air mass flow rate. For the same flow rate, the efficiency of the double pass is found to be higher than the single pass by 7-19.4%. Maximum efficiency obtained for the single and double pass air heater was 59.62% and 63.74% respectively for air mass flow rate of 0.038 kg/s. Moreover, the thermal efficiency further decreases by increasing the height of the first pass of the double pass solar air heater. The temperature difference between the outlet flow and the ambient, {delta}T, reduces as the air mass flow rate increase The result of a single or double solar air heater using steel wire mesh arrange in layers as an absorber plate and packing material when compared with a conventional solar air heater shows a much more substantial enhancement in the thermal efficiency. (author)

  12. Experimental investigation on carbon nano tubes coated brass rectangular extended surfaces

    International Nuclear Information System (INIS)

    Finned surface has been extensively used for free convection cooling of internal combustion engines and several electronic kits etc. Here rectangular brass fin was preferred for analysis. Thermocouples were attached all over the surface of the fin in equal distances. The measurement of surface temperature and calculated convective heat transfer rate were reported for several heat input values. The overall system performance can be improved by enhancing heat transfer rate of extended surfaces. Based on the above requirement, brass surface was coated by carbon nano tubes. The temperature and heat transfer characteristics were investigated using Taguchi method for experimental design. Finally the performances of coated and non-coated rectangular brass fins were compared. The average percentage of increase in heat transfer rate was proved around 12% for carbon nanocoated rectangular brass fins. - Graphical abstract: The designed Natural and Forced convection Heat Transfer Test Rig measures the enhanced rate of heat transfer for nano coated rectangular fins than in non-coated fins. Highlights: ? Rectangular brass fins were preferred for convective heat transfer process. ? The rectangular brass fins are coated with multi wall carbon nano tubes in EBPVD process with nanometer thickness. ? Temperature and heat transfer rate were investigated for nanocoated and non-coated fins by using Taguchi method. ? Multi wall carbon nanotubes act as a pin fin to enhance surface area for effective convective heat transfer rate.

  13. Test plan for Fauske and Associates to perform tube propagation experiments with simulated Hanford tank wastes

    International Nuclear Information System (INIS)

    This test plan, prepared at Pacific Northwest National Laboratory for Westinghouse Hanford Company, provides guidance for performing tube propagation experiments on simulated Hanford tank wastes and on actual tank waste samples. Simulant compositions are defined and an experimental logic tree is provided for Fauske and Associates (FAI) to perform the experiments. From this guidance, methods and equipment for small-scale tube propagation experiments to be performed at the Hanford Site on actual tank samples will be developed. Propagation behavior of wastes will directly support the safety analysis (SARR) for the organic tanks. Tube propagation may be the definitive tool for determining the relative reactivity of the wastes contained in the Hanford tanks. FAI have performed tube propagation studies previously on simple two- and three-component surrogate mixtures. The simulant defined in this test plan more closely represents actual tank composition. Data will be used to support preparation of criteria for determining the relative safety of the organic bearing wastes

  14. Test for Fauske and Associates to perform tube propagation experiments with simulated Hanford tank wastes

    International Nuclear Information System (INIS)

    This test plan, prepared at Pacific Northwest National Laboratory for Westinghouse Hanford Company, provides guidance for performing tube propagation experiments on simulated Hanford tank wastes and on actual tank waste samples. Simulant compositions are defined and an experimental logic tree is provided for Fauske and Associates (FAI) to perform the experiments. From this guidance, methods and equipment for small-scale tube propagation experiments to be performed at the Hanford Site on actual tank samples will be developed. Propagation behavior of wastes will directly support the safety analysis (SARR) for the organic tanks. Tube propagation may be the definitive tool for determining the relative reactivity of the wastes contained in the Hanford tanks. FAI have performed tube propagation studies previously on simple two- and three-component surrogate mixtures. The simulant defined in this test plan more closely represents actual tank composition. Data will be used to support preparation of criteria for determining the relative safety of the organic bearing wastes

  15. Effects of intraspecific variation in reproductive traits, pectoral fin use and burst swimming on metabolic rates and swimming performance in the Trinidadian guppy (Poecilia reticulata)

    DEFF Research Database (Denmark)

    Svendsen, Jon Christian; Banet, Amanda I.; Christensen, Rune Haubo Bojesen; Steffensen, John F.; Aarestrup, Kim

    2013-01-01

    There is considerable intraspecific variation in metabolic rates and locomotor performance in aquatic ectothermic vertebrates; however, the mechanistic basis remains poorly understood. Using pregnant Trinidadian guppies (Poecilia reticulata), a livebearing teleost, we examined the effects of reproductive traits, pectoral fin use and burse-assisted swimming on swimming metabolic rate, standard metabolic rate (MO2std) and prolonged swimming performance (Ucrit). Reproductive traits included reprodu...

  16. Heat transfer and pressure drop correlations for the multi-louvered fin compact heat exchangers

    International Nuclear Information System (INIS)

    Experimental studies on the air side heat transfer and pressure drop characteristics for 20 types of multi-louvered fin and flat tube heat exchangers were performed. A series of tests were conducted for air Reynolds numbers of 200-2500 based on the louver pitch with different fin pitch, fin height, fin thickness, fin louver angle and flow length at a constant tube side flow rate of 2.8m3/h.The air side thermal performance data were analyzed using the effectiveness-NTU method. Characteristics of the heat transfer and pressure drop for the different geometry parameters were reported in terms of Colburn j-factor and Fanning friction f-factor as a function of ReLp. The general correlations for the j and f factors were derived by regression analysis and F test of significance. The correlations of the j and f factors predict the test data within a rms error of +/-10% and +/-12%, and the mean deviations are 4.1% and 5.6%, respectively. In addition, two comparison methods were adopted to evaluate the air side thermal hydraulic performance of the multi-louvered fins

  17. Performance comparison of high speed microchannel plate photomultiplier tubes

    Science.gov (United States)

    Varghese, Thomas; Selden, Michael; Oldham, Thomas

    1993-01-01

    The transit time spread characteristics of high speed microchannel photomultipliers has improved since the upgrade of the NASA CDSLR network to MCP-PMT's in the mid-1980's. The improvement comes from the incorporation of 6 micron (pore size) microchannels and offers significant improvement to the satellite ranging precision. To examine the impact on ranging precision, two microchannel plate photomultiplier tubes (MCP-PMT) were evaluated for output pulse characteristics and temporal jitter. These were a Hamamatsu R 2566 U-7 MCP-PMT (6 micron) and an ITT 4129f MCP-PMT (12 micron).

  18. Performance of long straw tubes using dimethyl ether

    International Nuclear Information System (INIS)

    A cylindrical tracking detector with an inner radius of one meter employing straw tubes is being envisaged for the FINUDA experiment aimed at hyper-nuclear physics at DA?NE, the Frascati ?-factory. A prototype using several 10 mm and 20 mm diameter, two meter long aluminized mylar straws has been assembled and tested with a one GeV/c pion beam. While operating with dimethyl ether, gas gain, space resolution, and device systematics have been studied. A simple method of correction for systematics due to straw eccentricity has been developed and, once applied, a space resolution better than 40 ?m can be reached. (orig.)

  19. Performance of long straw tubes using dimethyl ether

    Science.gov (United States)

    Benussi, L.; Bertani, M.; Bianco, S.; Fabbri, F. L.; Gianotti, P.; Giardoni, M.; Guaraldo, C.; Lanaro, A.; Lucherini, V.; Mecozzi, A.; Passamonti, L.; Russo, V.; Sarwar, S.

    1995-02-01

    A cylindrical tracking detector with an inner radius of one meter employing straw tubes is being envisaged for the FINUDA experiment aimed at hyper-nuclear physics at DA?NE, the Frascati ?-factory. A prototype using several 10 mm and 20 mm diameter, two meter long aluminized mylar straws has been assembled and tested with a one GeV/ c pion beam. While operating with dimethyl ether, gas gain, space resolution, and device systematics have been studied. A simple method of correction for systematics due to straw eccentricity has been developed and, once applied, a space resolution better than 40 ?m can be reached.

  20. Enhancement of Performance of Shell and Tube Heat Exchanger Using Pertinent Leakage Flow Between Baffle and Tube Bundles

    International Nuclear Information System (INIS)

    In this study, the effects of the leakage flow between the baffle and tube bundles on the performance of a shell and tube heat exchanger (STHE) were examined using the commercial software ANSYS FLUENT v.14. A computational fluid dynamics model was developed for a small STHE with five different cases for the ratio of the leakage cross-sectional area to the baffle cross-sectional area, ranging from 0 to 40%, in order to determine the optimum leakage flow corresponding to the maximum outlet temperature. Using fixed tube wall and inlet temperatures for the shell side of the STHE, the flow and temperature fields were calculated by increasing the Reynolds number from 4952 to 14858. The present results showed that the outlet temperature, pressure drop, and heat transfer coefficient were strongly affected by the leakage flow, as well as the Reynolds number. In contrast with a previous researchers finding that the leakage flow led to simultaneous decreases in the pressure drop and heat transfer rate, the present study found that the pertinent leakage flow provided momentum in the recirculation zone near the baffle plate and thus led to the maximum outlet temperature, a small pressure drop, and the highest heat transfer rate. The optimum leakage flow was shown in the case with a ratio of 20% among the five different cases.

  1. Steam generator tube performance: experience with water-cooled nuclear power reactors during 1978

    International Nuclear Information System (INIS)

    The performance of steam generator tubes in water-cooled nuclear power reactors has been reviewed for 1978. Tube failures occurred at 31 of the 86 reactors surveyed. Causes of these failures and procedures designed to deal with them are described. A dramatic decrease in the number of tubes plugged was evident in 1978 compared to the previous year. This is attributed to diligent application of techniques developed from in-plant experience and research and development programs over the past several years. (auth)

  2. Functional and Biomechanical Performance of Stentless Extracellular Matrix Tricuspid Tube Graft

    DEFF Research Database (Denmark)

    Ropcke, Diana M; Ilkjær, Christine; Skov, Søren N; Tjørnild, Marcell J; Sørensen, Anders Vibæk; Jensen, Henrik; Jensen, Morten O J; Hjortdal, Vibeke E; Nielsen, Sten L

    2015-01-01

    BACKGROUND: Stentless porcine extracellular matrix tricuspid tubular valves have been developed for tricuspid valve reconstruction. The purpose of this study was to compare biomechanical and functional performance of native and tube graft valves in an acute porcine model. METHODS: Twenty-two 65-kg pigs were randomized to tube graft or control with native valve preservation. Anterior papillary muscle force was measured with a dedicated force transducer. Microtip pressure catheters were placed in ...

  3. Steam generator tube performance: experience with water-cooled nuclear power reactors during 1977

    International Nuclear Information System (INIS)

    The performance of steam generator tubes in water-cooled nuclear power reactors has been reviewed for 1977. Failures were reported in 34 of the 79 reactors surveyed. Causes of these failures and inspection and repair procedures designed to deal with them are presented. Although corrosion remained the leading cause of tube failures, specific mechanisms have been identified and methods of dealing with them developed. These methods are being applied and should lead to a reduction of corrosion failures in future. (author)

  4. Performance investigation of capillary tubes for machine tool coolers retrofitted with HFC-407C refrigerant

    Science.gov (United States)

    Wang, Fujen; Chang, Tongbou; Chiang, Weiming; Lee, Haochung

    2012-09-01

    The machine tool coolers are the best managers of coolant temperature in avoiding the deviation of spindle centerline for machine tools. However, the machine coolers are facing the compressed schedule to phase out the HCFC (hydro-chloro-floro-carbon) refrigerant and little attention has been paid to comparative study on sizing capillary tube for retrofitted HFC (hydro-floro-carbon) refrigerant. In this paper, the adiabatic flow in capillary tube is analyzed and modeled for retrofitting of HFC-407C refrigerant in a machine tool cooler system. A computer code including determining the length of sub-cooled flow region and the two phase region of capillary tube is developed. Comparative study of HCFC-22 and HFC-407C in a capillary tube is derived and conducted to simplify the traditional trial-and-error method of predicting the length of capillary tubes. Besides, experimental investigation is carried out by field tests to verify the simulation model and cooling performance of the machine tool cooler system. The results from the experiments reveal that the numerical model provides an effective approach to determine the performance data of capillary tube specific for retrofitting a HFC-407C machine tool cooler. The developed machine tool cooler system is not only directly compatible with new HFC-407C refrigerant, but can also perform a cost-effective temperature control specific for industrial machines.

  5. Flow and heat transfer enhancement in tube heat exchangers

    Science.gov (United States)

    Sayed Ahmed, Sayed Ahmed E.; Mesalhy, Osama M.; Abdelatief, Mohamed A.

    2015-08-01

    The performance of heat exchangers can be improved to perform a certain heat-transfer duty by heat transfer enhancement techniques. Enhancement techniques can be divided into two categories: passive and active. Active methods require external power, such as electric or acoustic field, mechanical devices, or surface vibration, whereas passive methods do not require external power but make use of a special surface geometry or fluid additive which cause heat transfer enhancement. The majority of commercially interesting enhancement techniques are passive ones. This paper presents a review of published works on the characteristics of heat transfer and flow in finned tube heat exchangers of the existing patterns. The review considers plain, louvered, slit, wavy, annular, longitudinal, and serrated fins. This review can be indicated by the status of the research in this area which is important. The comparison of finned tubes heat exchangers shows that those with slit, plain, and wavy finned tubes have the highest values of area goodness factor while the heat exchanger with annular fin shows the lowest. A better heat transfer coefficient ha is found for a heat exchanger with louvered finned and thus should be regarded as the most efficient one, at fixed pumping power per heat transfer area. This study points out that although numerous studies have been conducted on the characteristics of flow and heat transfer in round, elliptical, and flat tubes, studies on some types of streamlined-tubes shapes are limited, especially on wing-shaped tubes (Sayed Ahmed et al. in Heat Mass Transf 50: 1091-1102, 2014; in Heat Mass Transf 51: 1001-1016, 2015). It is recommended that further detailed studies via numerical simulations and/or experimental investigations should be carried out, in the future, to put further insight to these fin designs.

  6. Performance studies of tubular flat plate collectors

    International Nuclear Information System (INIS)

    Computations have been performed for flat plate efficiency factor, heat removal factor, heat gained by fluid for different materials used for the tubes and fins of flat plate tubular solar collectors. 3 refs, 17 figs, 4 tabs

  7. HEAT TRANSFER EVALUATION OF HFC-236EA WITH HIGH PERFORMANCE ENHANCED TUBES IN CONDENSATION AND EVAPORATION

    Science.gov (United States)

    The report gives results of an evaluation of the heat transfer performance of pure hydrofluorocarbon (HFC)-236ea for high performance enhanced tubes which had not been previously used in Navy shipboard chillers. Shell-side heat transfer coefficient data are presented for condensa...

  8. The Effect of the Capillary Tube Coil Number on the Refrigeration System Performance

    Directory of Open Access Journals (Sweden)

    Thamir K. Salim

    2012-06-01

    Full Text Available The capillary tube performance for (R134a is experimentally investigated. The experimental setup is a real vapor compression refrigeration system. All properties of the refrigeration system are measured for various mass flow rate from (13 – 23 kg/hr and capillary tube coil number (0-4 with fixed length (150 cm and capillary diameter(2.5mm.The results showed that the theoretical compression power increases by (65.8 % as the condenser temperature increases by (2.71%, also the theoretical compression power decreases by (10.3 % as the capillary tube coil number increases.The study shows also that the cooling capacity increases by (65.3% as the evaporator temperature increases by (8.4 %, and the cooling capacity increases by (1.6%as the capillary tube coil number increases in the range (0-4.The coefficient of performance decreases by (43.4 %, as the mass flow rateincreases by (76.9%, also the coefficient of performance increases by (13.51 % as thecapillary tube coil number increases in the range (0-4.Through this study, it was found that the best coil number in refrigeration cycle at the lowest mass flow rate (31 Kg/hr and at high mass flow rate (23 Kg/hr is (coil number = 4, this will give the highest performance, cooling capacity and lowest theoretical compression power.

  9. Functional and Biomechanical Performance of Stentless Extracellular Matrix Tricuspid Tube Graft : An Acute Experimental Porcine Evaluation

    DEFF Research Database (Denmark)

    Ropcke, Diana M; Ilkjær, Christine

    2015-01-01

    BACKGROUND: Stentless porcine extracellular matrix tricuspid tubular valves have been developed for tricuspid valve reconstruction. The purpose of this study was to compare biomechanical and functional performance of native and tube graft valves in an acute porcine model. METHODS: Twenty-two 65-kg pigs were randomized to tube graft or control with native valve preservation. Anterior papillary muscle force was measured with a dedicated force transducer. Microtip pressure catheters were placed in the right atrium and ventricle. Leaflet motion and three-dimensional valve geometry were evaluated using 13 sonomicrometry crystals: six in the tricuspid annulus, one on each leaflet free edge, one on each papillary muscle tip, and one in the right ventricular apex. RESULTS: No regurgitation and no significant differences in intracavitary pressures, annular motion, or leaflet excursion angles were observed after tube graft implantation (p > 0.05). Compared with the native valve, the tricuspid annulus, leaflet orificearea, annular diameters, and the septal segment of the annulus were significantly smaller in the tube graft group (p < 0.05). Maximum anterior papillary muscle force was significantly lower in the tube graft group (p < 0.005). The implantation technique led to an annular circumferential downsizing of 20% ± 17%. CONCLUSIONS: An extracellular matrix tube graft implanted in the tricuspid position produces a competent valve with physiologic performance that, despite downsizing, makes the tube graft an attractive alternative to valve replacement. The downsizing of the implantation should be considered when planning tube graft size and may be potentially beneficial by relieving tension on the repaired tissue, thereby increasing durability.

  10. Performance Study of Concrete-Filled Steel Tubes

    Directory of Open Access Journals (Sweden)

    Chair A.

    2014-04-01

    This type of structure can be used in Algeria for rehabilitating old buildings, or strengthening reinforced concretecolumns to improve their structural performance. However, new regulatory measures should be considered in order tointroduce this compound element in the construction.

  11. Procedimiento para el cálculo de circuitos en el modelado del flujo en intercambiadores de calor de aletas y tubos / Procedure for Calculating Circuits in the Modeling of Flow in fin-and-tube Heat Exchangers

    Scientific Electronic Library Online (English)

    Edwin, Córdoba-Tuta; David, Fuentes-Díaz.

    2015-01-01

    Full Text Available En este trabajo se presenta un procedimiento general para la simulación del comportamiento del flujo en los intercambiadores de tubos y aletas con una gran flexibilidad en el manejo de la información. Este procedimiento está basado en el uso de Programación Orientada a Objetos y específicamente al u [...] so de C++, esto debido a todas las ventajas de este tipo de programación. La entrada de datos se lleva a cabo por medio de archivos, de forma que programas de terceros puedan generar la configuración del intercambiador y permitir calcular el intercambiador en forma paramétrica. Los resultados para el análisis se presentan en tres formatos diferentes: valores separados por comas (CSV), texto plano estructurado y autodocumentado (XML) y un formato para la visualización gráfica de resultados (VTK). Abstract in english This paper presents a general method for simulating the flow behavior in the fin-and-tube heat exchangers with high flexibility in handling the information. This procedure is based on the use of Object-Oriented Programming and specifically using C++, this because of all the advantages of this type o [...] f programming. Data entry is carried out by files, so that third-party programs can generate configuration and permit calculation in parametric form. The results for the analysis are presented in three different formats: comma separated value (CSV), structured plain text and self-documenting (XML) and a graphical display of results (VTK).

  12. Heated ion implantation for high-performance and highly reliable silicon-on-insulator complementary metal–oxide–silicon fin field-effect transistors

    Science.gov (United States)

    Mizubayashi, Wataru; Onoda, Hiroshi; Nakashima, Yoshiki; Ishikawa, Yuki; Matsukawa, Takashi; Endo, Kazuhiko; Liu, Yongxun; O’uchi, Shinichi; Tsukada, Junichi; Yamauchi, Hiromi; Migita, Shinji; Morita, Yukinori; Ota, Hiroyuki; Masahara, Meishoku

    2015-04-01

    We have investigated the impact of heated ion implantation (I/I) on the performance and reliability of silicon-on-insulator (SOI) complementary metal–oxide–silicon (CMOS) fin field-effect transistors (FinFETs). An implantation temperature equal to and higher than 400 °C is needed to maintain the crystallinity of the Si substrate during I/I within the experimental conditions of ion species, implantation energy, and ion dose in this study. By heated I/I at 500 °C, the 11-nm-thick SOI layer perfectly maintains the crystallinity even after I/I, and a defect-free crystal is obtained by activation annealing. It was clarified that the cap layer is essential for the suppression of the out-diffusion during heated I/I. Heated I/I on the source and drain improves the on-current–off-current (Ion–Ioff), threshold voltage (Vth) variability, and bias temperature instability (BTI) characteristics of nMOS and pMOS FinFETs as compared with those after room-temperature I/I.

  13. A modular straw drift tube tracking system for the solenoidal detector collaboration experiment. Pt. II. Performance

    International Nuclear Information System (INIS)

    For pt.I see ibid., p.355-71, 1996. Several investigations were conducted to demonstrate the capabilities of a straw drift tube outer tracking system for the SDC detector as described in the previous article. These include electrical properties and aging properties of the tubes as well as measurements of electron drift times in a 2 T magnetic field. Measurements characterizing the radiation hardness of the processes used to fabricate the front-end electronics are also included. We present the performance characteristics of prototype straw modules read out through this front-end electronics as well as some data on the performance of the track trigger system. (orig.)

  14. Steady-state and transient heat transfer through fins of complex geometry

    Directory of Open Access Journals (Sweden)

    Taler Dawid

    2014-06-01

    Full Text Available Various methods for steady-state and transient analysis of temperature distribution and efficiency of continuous-plate fins are presented. For a constant heat transfer coefficient over the fin surface, the plate fin can be divided into imaginary rectangular or hexangular fins. At first approximate methods for determining the steady-state fin efficiency like the method of equivalent circular fin and the sector method are discussed. When the fin geometry is complex, thus transient temperature distribution and fin efficiency can be determined using numerical methods. A numerical method for transient analysis of fins with complex geometry is developed. Transient temperature distributions in continuous fins attached to oval tubes is computed using the finite volume - finite element methods. The developed method can be used in the transient analysis of compact heat exchangers to calculate correctly the heat flow rate transferred from the finned tubes to the fluid.

  15. A biorobotic model of the sunfish pectoral fin for investigations of fin sensorimotor control

    Energy Technology Data Exchange (ETDEWEB)

    Phelan, Chris; Tangorra, James [Department of Mechanical Engineering, Drexel University, Philadelphia, PA 19104 (United States); Lauder, George [Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138 (United States); Hale, Melina, E-mail: tangorra@coe.drexel.ed [Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637 (United States)

    2010-09-15

    A comprehensive understanding of the control of flexible fins is fundamental to engineering underwater vehicles that perform like fish, since it is the fins that produce forces which control the fish's motion. However, little is known about the fin's sensory system or about how fish use sensory information to modulate the fin and to control propulsive forces. As part of a research program that involves neuromechanical and behavioral studies of the sunfish pectoral fin, a biorobotic model of the pectoral fin and of the fin's sensorimotor system was developed and used to investigate relationships between sensory information, fin ray motions and propulsive forces. This robotic fin is able to generate the motions and forces of the biological fin during steady swimming and turn maneuvers, and is instrumented with a relatively small set of sensors that represent the biological lateral line and receptors hypothesized to exist intrinsic to the pectoral fin. Results support the idea that fin ray curvature, and the pressure in the flow along the wall that represents the fish body, capture time-varying characteristics of the magnitude and direction of the force created throughout a fin beat. However, none of the sensor modalities alone are sufficient to predict the propulsive force. Knowledge of the time-varying force vector with sufficient detail for the closed-loop control of fin ray motion will result from the integration of characteristics of many sensor modalities.

  16. A biorobotic model of the sunfish pectoral fin for investigations of fin sensorimotor control

    International Nuclear Information System (INIS)

    A comprehensive understanding of the control of flexible fins is fundamental to engineering underwater vehicles that perform like fish, since it is the fins that produce forces which control the fish's motion. However, little is known about the fin's sensory system or about how fish use sensory information to modulate the fin and to control propulsive forces. As part of a research program that involves neuromechanical and behavioral studies of the sunfish pectoral fin, a biorobotic model of the pectoral fin and of the fin's sensorimotor system was developed and used to investigate relationships between sensory information, fin ray motions and propulsive forces. This robotic fin is able to generate the motions and forces of the biological fin during steady swimming and turn maneuvers, and is instrumented with a relatively small set of sensors that represent the biological lateral line and receptors hypothesized to exist intrinsic to the pectoral fin. Results support the idea that fin ray curvature, and the pressure in the flow along the wall that represents the fish body, capture time-varying characteristics of the magnitude and direction of the force created throughout a fin beat. However, none of the sensor modalities alone are sufficient to predict the propulsive force. Knowledge of the time-varying force vector with sufficient detail for the closed-loop control of fin ray motion will result from the integration of characteristics of many sensor modalities.

  17. Performance demonstration tests for eddy current inspection of steam generator tubing

    International Nuclear Information System (INIS)

    This report describes the methodology and results for development of performance demonstration tests for eddy current (ET) inspection of steam generator tubes. Statistical test design principles were used to develop the performance demonstration tests. Thresholds on ET system inspection performance were selected to ensure that field inspection systems would have a high probability of detecting and and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented in detail. Statistical test design calculations for probability of detection and flaw sizing tests are described. A recommended performance demonstration test based on the design calculations is presented. A computer program for grading the probability of detection portion of the performance demonstration test is given

  18. Effects of draft tube on the hydraulic performance of a Francis turbine

    Science.gov (United States)

    Jeon, J. H.; Byeon, S. S.; Kim, Y. J.

    2013-12-01

    The draft tube is an important component of a Francis turbine which influences the hydraulic performance. It is located just under the runner and allowed to decelerate the flow velocity exiting the runner, thereby converting the excess of kinetic energy into static pressure. In this study, we have numerically investigated the hydraulic performance of a Francis turbine on the 15MW hydropower generation with various design parameters (three types of draft tube, thickness of guide vane) through a three-dimensional numerical method with the SST turbulent model. The vortex rope characteristics of the draft tube were confirmed. The results of the vortex flow fields and flow characteristics were graphically depicted with different design parameters and operating conditions.

  19. Heat transfer augmentation due to surface radiative exchange effect of internal fins in an annulus

    International Nuclear Information System (INIS)

    Heat transfer augmentation due to surface radiation in an annulus with fins was investigated both theoretically and experimentally for fully developed laminar flow. The system considered in the present study was an array of axially internal and straight fins attached to the outer tube wall. Analytical solutions were given for 4, 8, 16, 24, 32 fins and for the ratios of the fin height to the passage clearance, 0, 0.2, 0.4, 0.5, 0.6, 0.8. The experiments were performed with air as the working fluid for radius ratio of 1.45, 16 fins and for Reynolds numbers ranging from 500 to 2000. The numerically predicted results of the convective/radiative heat transfer for the present case were in good agreement with the experimental data. It was found that the heat transfer augmentation coefficient attained a maximum value of 1.45 for 32 fins and for a dimensionless fin height of 0.65

  20. Coupled heat and mass transfer in absorption of water vapor into LiBr-H2O solution flowing on finned inclined surfaces

    International Nuclear Information System (INIS)

    The absorption characteristics of water vapor into a LiBr-H2O solution flowing down on finned inclined surfaces are numerically investigated in order to study the absorbing performances of different surface shapes of finned tubes as an absorber element. A three-dimensional numerical model is developed. The momentum, energy, and diffusion equations are solved simultaneously using a finite difference method. In order to obtain the temperature and concentration distributions, the Runge-Kutta and the successive over relaxation methods are used. The flat, circular, elliptic, and parabolic shapes of the tube surfaces are considered in order to find the optimal surface shapes for absorption. In addition, the effects of the fin intervals and Rynolds numbers are studied. The results show that the absorption mainly happens near the fin tip due to the temperature and concentration gradient, and the absorbing performance of the parabolic surface is better than those of the other surfaces

  1. Improving heat exchanger performance by using on-line automatic tube cleaning system

    Energy Technology Data Exchange (ETDEWEB)

    Someah, Kaveh; Beauchesne, Guy [OVIVO Water (United States)], email: kaveh.someah@ovivowater.com, email: guy.beauchesne@ovivowater.com

    2011-07-01

    In this presentation, OVIVO demonstrates an innovative solution for enhancing the performance and output of heat exchangers used in oil recovery plants. The solution proposed for reducing tube failure due to deposit buildup, corrosion, micro fouling, and scaling caused by the high mineral content of the water used, is to use an on-line automatic tube cleaning system (ATCS). The first ATCS type is the ball type, which injects rubber balls into the water entering the heat exchanger. The scrubbing and wiping action of the balls keeps the tubes clean, and the balls are subsequently collected by means of a strainer and can be re-circulated as needed. A second system aligns a brush and basket to each tube and, by periodically reversing water flow using a diverter valve, cleans each tube several times daily without process interruption or the need for unit shut down. The use of ATCS has been proven to improve plant performance and increase output while reducing operating and maintenance costs.

  2. The ATLAS Transition Radiation Tracker (TRT) proportional drift tube: design and performance

    International Nuclear Information System (INIS)

    A straw proportional counter is the basic element of the ATLAS Transition Radiation Tracker (TRT). Its detailed properties as well as the main properties of a few TRT operating gas mixtures are described. Particular attention is paid to straw tube performance in high radiation conditions and to its operational stability

  3. Muscle activity during knee-extension strengthening exercise performed with elastic tubing and isotonic resistance

    DEFF Research Database (Denmark)

    Jakobsen, Markus Due; Sundstrup, Emil; Andersen, Christoffer H; Bandholm, Thomas; Thorborg, Kristian; Zebis, Mette Kreutzfeldt; Andersen, Lars L

    2012-01-01

    While elastic resistance training, targeting the upper body is effective for strength training, the effect of elastic resistance training on lower body muscle activity remains questionable. The purpose of this study was to evaluate the EMG-angle relationship of the quadriceps muscle during 10-RM knee-extensions performed with elastic tubing and an isotonic strength training machine.

  4. High Fin Width Mosfet Using Gaa Structure

    Directory of Open Access Journals (Sweden)

    S.L.Tripathi

    2012-11-01

    Full Text Available This paper describes the design and optimization of gate-all-around (GAA MOSFETs structures. The optimum value of Fin width and Fin height are investigated for superior subthreshold behavior. Also the performance of Fin shaped GAA with gate oxide HfO2 are simulated and compared with conventional gate oxide SiO2 for the same structure. As a result, it was observed that the GAA with high K dielectric gate oxide has more possibility to optimize the Fin width with improved performance. All the simulations are performed on 3-D TCAD device simulator.

  5. Quench gas and preamplifier selection influence on 3He tube performance for spent fuel applications

    International Nuclear Information System (INIS)

    Current 3He tubes utilized in neutron coincidence counting use different quench gas admixtures to shorten the avalanche process. In addition amplifier modules with different shaping characteristics are used to process detector signals. Both of these aspects affect the detector response. In the current paper, 3He tubes with several quench gas admixtures (CO2, N2, Ar+CH4 and CF4) and amplifier modules (PDT, AMPTEK, BOT) are compared. The plateau characteristics, gamma-sensitivity and deadtime of individual counters in combination with the listed amplifier modules are compared to determine optimum amplifier module/counter performance for the spent fuel applications.

  6. Performance of drift-tube detectors at high counting rates for high-luminosity LHC upgrades

    Energy Technology Data Exchange (ETDEWEB)

    Bittner, Bernhard; Dubbert, Jörg; Kortner, Oliver [Max-Planck-Institut für Physik, Munich (Germany); Kroha, Hubert, E-mail: kroha@mppmu.mpg.de [Max-Planck-Institut für Physik, Munich (Germany); Manfredini, Alessandro; Nowak, Sebastian; Ott, Sebastian; Richter, Robert; Schwegler, Philipp; Zanzi, Daniele [Max-Planck-Institut für Physik, Munich (Germany); Biebel, Otmar; Hertenberger, Ralf; Ruschke, Alexander; Zibell, Andre [Ludwig-Maximilians University, Garching (Germany)

    2013-12-21

    The performance of pressurized drift-tube detectors at very high background rates has been studied at the Gamma Irradiation Facility (GIF) at CERN and in an intense 20 MeV proton beam at the Munich Van-der-Graaf tandem accelerator for applications in large-area precision muon tracking at high-luminosity upgrades of the Large Hadron Collider (LHC). The ATLAS muon drift-tube (MDT) chambers with 30 mm tube diameter have been designed to cope with ? and neutron background hit rates of up to 500 Hz/cm{sup 2}. Background rates of up to 14 kHz/cm{sup 2} are expected at LHC upgrades. The test results with standard MDT readout electronics show that the reduction of the drift-tube diameter to 15 mm, while leaving the operating parameters unchanged, vastly increases the rate capability well beyond the requirements. The development of new small-diameter muon drift-tube (sMDT) chambers for LHC upgrades is completed. Further improvements of tracking efficiency and spatial resolution at high counting rates will be achieved with upgraded readout electronics employing improved signal shaping for high counting rates.

  7. Performance of the Hamamatsu R11410 photomultiplier tube in cryogenic xenon environments

    International Nuclear Information System (INIS)

    The Hamamatsu R11410 photomultiplier, a tube of 3'' diameter and with a very low intrinsic radioactivity, is an interesting light sensor candidate for future experiments using liquid xenon (LXe) as target for direct dark matter searches. We have performed several experiments with the R11410 with the goal of testing its performance in environments similar to a dark matter detector setup. In particular, we examined its long-term behavior and stability in LXe and its response in various electric field configurations.

  8. Improving the Performance of Two-Stage Gas Guns By Adding a Diaphragm in the Pump Tube

    Science.gov (United States)

    Bogdanoff, D. W.; Miller, Robert J.

    1995-01-01

    Herein, we study the technique of improving the gun performance by installing a diaphragm in the pump tube of the gun. A CFD study is carried out for the 0.28 in. gun in the Hypervelocity Free Flight Radiation (HFF RAD) range at the NASA Ames Research Center. The normal, full-length pump tube is studied as well as two pump tubes of reduced length (approximately 75% and approximately 33% of the normal length). Significant improvements in performance are calculated to be gained for the reduced length pump tubes upon the addition of the diaphragm. These improvements are identified as reductions in maximum pressures in the pump tube and at the projectile base of approximately 20%, while maintaining the projectile muzzle velocity or as increases in muzzle velocity of approximately 0.5 km/sec while not increasing the maximum pressures in the gun. Also, it is found that both guns with reduced pump tube length (with diaphragms) could maintain the performance of gun with the full length pump tube without diaphragms, whereas the guns with reduced pump tube lengths without diaphragms could not. A five-shot experimental investigation of the pump tube diaphragm technique is carried out for the gun with a pump tube length of 75% normal. The CFD predictions of increased muzzle velocity are borne out by the experimental data. Modest, but useful muzzle velocity increases (2.5 - 6%) are obtained upon the installation of a diaphragm, compared to a benchmark shot without a diaphragm.

  9. QuantiFERON-TB Gold In-Tube test performance in Denmark

    DEFF Research Database (Denmark)

    Hermansen, Thomas; Lillebaek, Troels; Hansen, Ann-Brit E; Andersen, Peter H; Ravn, Pernille

    2014-01-01

    BACKGROUND: Little is known about the QuantiFERON-TB Gold In-Tube Test (QFT) in extreme age groups. The test performance has been reported to be impaired in children and elderly, but reports are diverging. The aim of this study was to evaluate QFT performance in patients with and without Tuberculosis (TB). METHODS: A retrospective study analysing the results of 18,850 QFT performed in Denmark 2005-2010. The effect of age, sex, localisation of TB, and result of culture on QFT performance (positiv...

  10. QuantiFERON–TB Gold In-Tube test performance in Denmark

    DEFF Research Database (Denmark)

    Hermansen, Thomas; Lillebaek, Troels; Hansen, Ann-Brit E; Andersen, Peter H; Ravn, Pernille

    2014-01-01

    BACKGROUND: Little is known about the QuantiFERON-TB Gold In-Tube Test (QFT) in extreme age groups. The test performance has been reported to be impaired in children and elderly, but reports are diverging. The aim of this study was to evaluate QFT performance in patients with and without Tuberculosis (TB). METHODS: A retrospective study analysing the results of 18,850 QFT performed in Denmark 2005-2010. The effect of age, sex, localisation of TB, and result of culture on QFT performance (positiv...

  11. Wave-shaping of pulse tube cryocooler components for improved performance

    Science.gov (United States)

    Antao, Dion Savio; Farouk, Bakhtier

    2014-11-01

    The method of wave-shaping acoustic resonators is applied to an inertance type cryogenic pulse tube refrigerator (IPTR) to improve its performance. A detailed time-dependent axisymmetric experimentally validated computational fluid dynamic (CFD) model of the PTR is used to predict its performance. The continuity, momentum and energy equations are solved for both the refrigerant gas (helium) and the porous media regions (the regenerator and the three heat-exchangers) in the PTR. An improved representation of heat transfer in the porous media is achieved by employing a thermal non-equilibrium model to couple the gas and solid (porous media) energy equations. The wave-shaped regenerator and pulse tube studied have cone geometries and the effects of different cone angles and the orientation (nozzle v/s diffuser mode) on the system performance are investigated. The resultant spatio-temporal pressure, temperature and velocity fields in the regenerator and pulse tube components are evaluated. The performance of these wave-shaped PTRs is compared to the performance of a non wave-shaped system with cylindrical components. Better cooling is predicted for the cryocooler using wave-shaped components oriented in the diffuser mode.

  12. Thermal and Sensitivity Analysis of Multi-Fin Devices

    OpenAIRE

    Swahn, B; Hassoun, S.

    2006-01-01

    As device dimensions shrink into the nanometer range, power and performance constraints prohibit the longevity of traditional MOS devices in circuit design. A finFET, a quasi-planar double-gated device, has emerged as a replacement. FinFETs are formed by creating a silicon em fin which protrudes out of the wafer, wrapping a gate around the fin, and then doping the ends of the fin to form the source and drain. Wider finFETs are formed using multiple fins between the source and drain regions. W...

  13. Experimental characterization of thermal hydraulic performance of louvered brazed plate fin heat exchangers / Caracterización térmico-hidraulica experimental del rendimiento de intercambiadores de placa y barras con aletas ventaneadas

    Scientific Electronic Library Online (English)

    John, Turizo-Santos; Oscar, Barros-Ballesteros; Armando, Fontalvo-Lascano; Ricardo, Vasquez-Padilla; Antonio, Bula-Silvera.

    2015-03-01

    Full Text Available Las aletas tipo persianas se utilizan comúnmente en los intercambiadores de calor compactos para aumentar el área de superficie, la turbulencia, y producir una regeneración de la capa límite requerido para mejorar el rendimiento de transferencia de calor sin un aumento significativo en la caída de p [...] resión en comparación con otro tipo aletas. Un estudio experimental sobre la transferencia de calor y la caída de presión del lado del aire en aletas tipo persiana con patrón simétrico usada en intercambiadores de calor de placas soldadas, ha sido llevado a cabo. El números de Reynolds osciló entre 350 - 1270, basado en el pitch de la aleta, mientras se mantuvo un caudal de agua constante de 1,82 m³/h. La transferencia de calor y caída de presión para la geometría probada se presenta en términos del factor de Colburn (j) y el factor de fricción de Fanning (f) como función del número de Reynolds. Los resultados experimentales para j y f presentan un comportamiento acorde comparados con los modelos de regresión sugeridos para intercambiadores de calor compactos con aletas tipo persiana y tubos planos, presentando una desviación de 5,48 % y 5,39 % respectivamente. Por otra parte, cuando se compara con el análisis de CFD para la misma geometría, se obtiene una desviación media de 6,3%. Por último, un modelo de regresión para los factores j y f se logró con base en el número de Reynolds, presentando una desviación de 1,51 % y 2,19 % respectivamente. Abstract in english Louvered fins are commonly used in compact heat exchangers to increase the surface area, turbulence, and initiate new boundary layer growth required to improve the heat transfer performance without a significant increase in pressure drop compared with other fins. An experimental study on the air sid [...] e heat transfer and pressure drop characteristics for a louvered fin with symmetrical patterns in brazed plate heat exchangers had been performed. Reynolds numbers ranged from 350 - 1270, based on the louver pitch while a constant 1.82 m3/h water flow was held. The heat transfer and pressure drop for the geometry tested was reported in terms of Colburn factor (j) and Fanning friction factor (f) as a function of the Reynolds number. The experimental results for j and f are in good agreement compared to regression models suggested for compact heat exchanger with louvered fin and flat tubes, obtaining a deviation of 5.48% and 5.39% respectively. Moreover, when compared to CFD analysis for the same geometry, an average deviation of 6.3% is obtained. Finally a regression model for j and f factors was attained based on the Reynolds number, presenting a deviation of 1.51% and 2.19% respectively.

  14. Survey of the heat transfer correlations for helically coiled tubes to analyze the performance of the SMART steam generator

    International Nuclear Information System (INIS)

    Helically coiled tubes are widely used for making compact heat exchangers. In the nuclear industry, once-through helically coiled heat exchangers are one of the options for small and medium sized reactors. SMART, which has been designed at KAERI, has 12 cassettes of once-through type heat exchangers using helically coiled tubes as a steam generator. To analyze the performance of the steam generator, information on the heat transfer characteristics of the helical coil tubes is required

  15. Performance of a 260 Hz pulse tube cooler with metal fiber as the regenerator material

    Science.gov (United States)

    Wang, Xiaotao; Zhang, Shuang; Yu, Guoyao; Dai, Wei; Luo, Ercang

    2014-01-01

    Pulse tube coolers operating at higher frequency lead to a high energy density and result in a more compact system. This paper describes the performance of a 300 Hz pulse tube cooler driven by a linear compressor. Such high frequency operation leads to decreased thermal penetration, which requires a smaller hydraulic diameter and smaller wire diameter in the regenerator. In our previous experiments, the stainless steel mesh with a mesh number of 635 was used as the regenerator material, and a no-load temperature of 63 K was obtained. Both the numerical and experimental results indicate this material causes a large loss in the regenerator. A stainless steel fiber regenerator is introduced and studied in this article. Because this fiber has a wide range of wire diameter and porosity, such material might be more suitable for higher frequency pulse tube coolers. With the fiber as the regenerator material and after a series of optimizations, a no-load temperature of 45 K is acquired in the experiment. Influences of various parameters such as frequency and inertance tube length have been investigated experimentally.

  16. A minichannel aluminium tube heat exchanger - Pt. 3: Condenser performance with propane

    Energy Technology Data Exchange (ETDEWEB)

    Fernando, Primal; Palm, Bjoern; Ameel, Tim; Lundqvist, Per; Granryd, Eric [Department of Energy Technology, Division of Applied Thermodynamics and Refrigeration, Royal Institute of Technology (KTH), Stockholm (Sweden)

    2008-06-15

    This paper reports heat transfer results obtained during condensation of refrigerant propane inside a minichannel aluminium heat exchanger vertically mounted in an experimental setup simulating a water-to-water heat pump. The condenser was constructed of multiport minichannel aluminium tubes assembled as a shell-and-tube heat exchanger. Propane vapour entered the condenser tubes via the top end and exited sub-cooled from the bottom. Coolant water flowed upward on the shell-side. The heat transfer areas of the tube-side and the shell-side of the condenser were 0.941 m{sup 2} and 0.985 m{sup 2}, respectively. The heat transfer rate between the two fluids was controlled by varying the evaporation temperature while the condensation temperature was fixed. The applied heat transfer rate was within 3900-9500 W for all tests. Experiments were performed at constant condensing temperatures of 30{sup o}C, 40{sup o}C and 50{sup o}C, respectively. The cooling water flow rate was maintained at 11.90 l min{sup -1} for all tests. De-superheating length, two-phase length, sub-cooling length, local heat transfer coefficients and average heat transfer coefficients of the condenser were calculated. The experimental heat transfer coefficients were compared with predictions from correlations found in the literature. The experimental heat transfer coefficients in the different regions were higher than those predicted by the available correlations. (author)

  17. Thermal performance testing of two Thales 9310 pulse-tube cryocoolers for PHyTIR

    International Nuclear Information System (INIS)

    PHyTIR is a NASA-funded technology demonstration for a near-term earth-observing instrument in the thermal infrared spectrum, intended for use in the HyspIRI mission. PHyTIR will use two Thales 9310 single-stage pulse tube cryocoolers, one to directly cool the FPA, the other to simulate a passive radiator. We report performance measurements for the two Thales 9310 cryocoolers intended for inclusion in the PHyTIR demonstrator

  18. Thermal performance testing of two Thales 9310 pulse-tube cryocoolers for PHyTIR

    Energy Technology Data Exchange (ETDEWEB)

    Paine, Christopher G. [Jet Propulsion Laboratory, California Institute of Technology 4800 Oak Grove Drive, Pasadena CA 91109 (United States)

    2014-01-29

    PHyTIR is a NASA-funded technology demonstration for a near-term earth-observing instrument in the thermal infrared spectrum, intended for use in the HyspIRI mission. PHyTIR will use two Thales 9310 single-stage pulse tube cryocoolers, one to directly cool the FPA, the other to simulate a passive radiator. We report performance measurements for the two Thales 9310 cryocoolers intended for inclusion in the PHyTIR demonstrator.

  19. Thermal performance testing of two Thales 9310 pulse-tube cryocoolers for PHyTIR

    Science.gov (United States)

    Paine, Christopher G.

    2014-01-01

    PHyTIR is a NASA-funded technology demonstration for a near-term earth-observing instrument in the thermal infrared spectrum, intended for use in the HyspIRI mission. PHyTIR will use two Thales 9310 single-stage pulse tube cryocoolers, one to directly cool the FPA, the other to simulate a passive radiator. We report performance measurements for the two Thales 9310 cryocoolers intended for inclusion in the PHyTIR demonstrator.

  20. Muscle activity during knee-extension strengthening exercise performed with elastic tubing and isotonic resistance

    DEFF Research Database (Denmark)

    Jakobsen, Markus Due; Sundstrup, Emil; Andersen, Christoffer H; Bandholm, Thomas; Thorborg, Kristian; Zebis, Mette K; Andersen, Lars L

    2012-01-01

    BACKGROUND/PURPOSE: While elastic resistance training, targeting the upper body is effective for strength training, the effect of elastic resistance training on lower body muscle activity remains questionable. The purpose of this study was to evaluate the EMG-angle relationship of the quadriceps muscle during 10-RM knee-extensions performed with elastic tubing and an isotonic strength training machine. METHODS: 7 women and 9 men aged 28-67 years (mean age 44 and 41 years, respectively) participa...

  1. A model for the performance of a vertical tube condenser in the presence of noncondensable gases

    International Nuclear Information System (INIS)

    Some proposed vertical tube condensers are designed to operate at high noncondensable fractions, which warrants a simple model to predict their performance. Models developed thus far are usually non self-contained as they require the specification of the wall temperature to predict the local condensation rate. The present model attempts to fill this gap by addressing the secondary side heat transfer as well. Starting with momentum balance which includes the effect of interfacial shear stress, a Nusselt-type algebraic equation is derived for the film thickness as a function of flow and geometry parameters. The heat and mass transfer analogy relations are then invoked to deduce the condensation rate of steam onto the tube wall. Lastly, the heat transfer to the secondary side is modelled to include cooling by forced, free or mixed convection flows. The model is used for parametric simulations to determine the impact on the condenser performance of important factors such as the inlet gas fraction, the mixture inlet flowrate, the total pressure, and the molecular weight of the noncondensable gas. The model performed simulations of some experiments with pure steam and air-steam mixtures flowing down a vertical tube. The model predicts the data quite well

  2. A model for the performance of a vertical tube condenser in the presence of noncondensable gases

    Energy Technology Data Exchange (ETDEWEB)

    Guentay, A.D.S.

    1995-09-01

    Some proposed vertical tube condensers are designed to operate at high noncondensable fractions, which warrants a simple model to predict their performance. Models developed thus far are usually non self-contained as they require the specification of the wall temperature to predict the local condensation rate. The present model attempts to fill this gap by addressing the secondary side heat transfer as well. Starting with momentum balance which includes the effect of interfacial shear stress, a Nusselt-type algebraic equation is derived for the film thickness as a function of flow and geometry parameters. The heat and mass transfer analogy relations are then invoked to deduce the condensation rate of steam onto the tube wall. Lastly, the heat transfer to the secondary side is modelled to include cooling by forced, free or mixed convection flows. The model is used for parametric simulations to determine the impact on the condenser performance of important factors such as the inlet gas fraction, the mixture inlet flowrate, the total pressure, and the molecular weight of the noncondensable gas. The model performed simulations of some experiments with pure steam and air-steam mixtures flowing down a vertical tube. The model predicts the data quite well.

  3. Improved Performance of an Indigenous Stirling Type Pulse Tube Cooler and Pressure Wave Generator

    Science.gov (United States)

    Kumar, J. Kranthi; Jacob, S.; Karunanithi, R.; Narasimham, G. S. V. L.; Damu, C.; Praveen, T.; Samir, M.

    Sustained efforts have been made in our laboratory to improve the performance of an indigenously developed pressure wave gen- erator by reducing the mechanical losses and the required input power. An acoustically matching pulse tube cooler, with a design target of 0.5 W at 80 K, was designed using Sage and experience gained from previous studies. The pulse tube cooler was fabri- cated and tested. The effect of regenerator stacking pattern on the cooler performance was studied by filling the regenerator with mesh of the same size #400 and with multi meshes #250, 325, 400. In present experiments, regenerator with #400 mesh at 30 bar filling pressure performed better with more energy efficiency. A no load temperature of 74 K was achieved with input power of 59 W corresponding to a cooling power of 0.22 W at 80 K. Parasitic heat load to the cooler was measured be 0.68 W. This heat load is primarily by heat conduction through the regenerator and pulse tube wall. By reducing the wall thickness from 0.30 mm to 0.15 mm, the parasitic loads can be reduced by 50%.

  4. Experimental determination of shell side heat transfer coefficient and pressure drop for an oil cooler shell-and-tube heat exchanger with three different tube bundles

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, R.; Hosseini-Ghaffar, A. [Faculty of Mechanical Engineering Amirkabir University of Technology, 424 Hafez Avenue, P.O. Box 15875-4413, Tehran (Iran); Soltani, M. [Mechanical Systems Department, Niroo research Institute (NRI), End of Pounak Bakhtari Blvd., P.O. Box 14665-517, Shahrak Gharb, Tehran (Iran)

    2007-04-15

    In this paper, the heat transfer coefficient and pressure drop on the shell side of a shell-and-tube heat exchanger have been experimentally obtained for three different types of copper tubes (smooth, corrugated and with micro-fins). Also, experimental data has been compared with theoretical data available. Correlations have been suggested for both pressure drop and Nusselt number for the three tube types. A shell-and-tube heat exchanger of an oil cooler used in a power transformer has been modeled and built for this experimental work in order to investigate the effect of surface configuration on the shell side heat transfer as well as the pressure drop of the three types of tube bundles. The bundles with the same geometry, configuration, number of baffles and length, but with different external tube surfaces inside the same shell were used for the experiment. Corrugated and micro-fin tubes have shown degradation of performance at a Reynolds number below a certain value (Re<400). At a higher Reynolds number the performance of the heat exchanger greatly improved for micro-finned tubes. (author)

  5. Undulating fins produce off-axis thrust and flow structures.

    Science.gov (United States)

    Neveln, Izaak D; Bale, Rahul; Bhalla, Amneet Pal Singh; Curet, Oscar M; Patankar, Neelesh A; MacIver, Malcolm A

    2014-01-15

    While wake structures of many forms of swimming and flying are well characterized, the wake generated by a freely swimming undulating fin has not yet been analyzed. These elongated fins allow fish to achieve enhanced agility exemplified by the forward, backward and vertical swimming capabilities of knifefish, and also have potential applications in the design of more maneuverable underwater vehicles. We present the flow structure of an undulating robotic fin model using particle image velocimetry to measure fluid velocity fields in the wake. We supplement the experimental robotic work with high-fidelity computational fluid dynamics, simulating the hydrodynamics of both a virtual fish, whose fin kinematics and fin plus body morphology are measured from a freely swimming knifefish, and a virtual rendering of our robot. Our results indicate that a series of linked vortex tubes is shed off the long edge of the fin as the undulatory wave travels lengthwise along the fin. A jet at an oblique angle to the fin is associated with the successive vortex tubes, propelling the fish forward. The vortex structure bears similarity to the linked vortex ring structure trailing the oscillating caudal fin of a carangiform swimmer, though the vortex rings are distorted because of the undulatory kinematics of the elongated fin. PMID:24072799

  6. Analysis of critical heat flux during subcooled boiling for finned fuel elements

    International Nuclear Information System (INIS)

    Experimental and analytical studies were performed to determine the critical heat flux (CHF) during subcooled boiling on finned fuel elements. Tests were conducted in a vertical, concentric-annulus test section consisting of a glass tube containing a finned heater element with either six, eight, or ten longitudinal fins. The phenomena leading to CHF are described and the parametric trends are discussed.A two-dimensional finite-element heat transfer model using the Galerkin method was used to analyse the experimental data to obtain CHF values. A dimensionless correlation was derived to predict the CHF values during subcooled boiling. Over 90% of the predicted CHF values agreed with those obtained from the two-dimensional analysis within ±30%. ((orig.))

  7. Performance of the CMS drift-tube chamber local trigger with cosmic rays

    CERN Document Server

    Chatrchyan, S; Sirunyan, A M; Adam, W; Arnold, B; Bergauer, H; Bergauer, T; Dragicevic, M; Eichberger, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kastner, K; Krammer, M; Liko, D; Magrans de Abril, I; Mikulec, I; Mittermayr, F; Neuherz, B; Oberegger, M; Padrta, M; Pernicka, M; Rohringer, H; Schmid, S; Schöfbeck, R; Schreiner, T; Stark, R; Steininger, H; Strauss, J; Taurok, A; Teischinger, F; Themel, T; Uhl, D; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C E; Chekhovsky, V; Dvornikov, O; Emeliantchik, I; Litomin, A; Makarenko, V; Marfin, I; Mossolov, V; Shumeiko, N; Solin, A; Stefanovitch, R; Suarez Gonzalez, J; Tikhonov, A; Fedorov, A; Karneyeu, A; Korzhik, M; Panov, V; Zuyeuski, R; Kuchinsky, P; Beaumont, W; Benucci, L; Cardaci, M; De Wolf, E A; Delmeire, E; Druzhkin, D; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Adler, V; Beauceron, S; Blyweert, S; D'Hondt, J; De Weirdt, S; Devroede, O; Heyninck, J; Kalogeropoulos, A; Maes, J; Maes, M; Mozer, M U; Tavernier, S; Van Doninck, W; Van Mulders, P; Villella, I; Bouhali, O; Chabert, E C; Charaf, O; Clerbaux, B; De Lentdecker, G; Dero, V; Elgammal, S; Gay, A P R; Hammad, G H; Marage, P E; Rugovac, S; Vander Velde, C; Vanlaer, P; Wickens, J; Grunewald, M; Klein, B; Marinov, A; Ryckbosch, D; Thyssen, F; Tytgat, M; Vanelderen, L; Verwilligen, P; Basegmez, S; Bruno, G; Caudron, J; Delaere, C; Demin, P; Favart, D; Giammanco, A; Grégoire, G; Lemaitre, V; Militaru, O; Ovyn, S; Piotrzkowski, K; Quertenmont, L; Schul, N; Beliy, N; Daubie, E; Alves, G A; Pol, M E; Souza, M H G; Carvalho, W; De Jesus Damiao, D; De Oliveira Martins, C; Fonseca De Souza, S; Mundim, L; Oguri, V; Santoro, A; Silva Do Amaral, S M; Sznajder, A; Fernandez Perez Tomei, T R; Ferreira Dias, M A; Gregores, E M; Novaes, S F; Abadjiev, K; Anguelov, T; Damgov, J; Darmenov, N; Dimitrov, L; Genchev, V; Iaydjiev, P; Piperov, S; Stoykova, S; Sultanov, G; Trayanov, R; Vankov, I; Dimitrov, A; Dyulendarova, M; Kozhuharov, V; Litov, L; Marinova, E; Mateev, M; Pavlov, B; Petkov, P; Toteva, Z; Chen, G M; Chen, H S; Guan, W; Jiang, C H; Liang, D; Liu, B; Meng, X; Tao, J; Wang, J; Wang, Z; Xue, Z; Zhang, Z; Ban, Y; Cai, J; Ge, Y; Guo, S; Hu, Z; Mao, Y; Qian, S J; Teng, H; Zhu, B; Avila, C; Baquero Ruiz, M; Carrillo Montoya, C A; Gomez, A; Gomez Moreno, B; Ocampo Rios, A A; Osorio Oliveros, A F; Reyes Romero, D; Sanabria, J C; Godinovic, N; Lelas, K; Plestina, R; Polic, D; Puljak, I; Antunovic, Z; Dzelalija, M; Brigljevic, V; Duric, S; Kadija, K; Morovic, S; Fereos, R; Galanti, M; Mousa, J; Papadakis, A; Ptochos, F; Razis, P A; Tsiakkouri, D; Zinonos, Z; Hektor, A; Kadastik, M; Kannike, K; Müntel, M; Raidal, M; Rebane, L; Anttila, E; Czellar, S; Härkönen, J; Heikkinen, A; Karimäki, V; Kinnunen, R; Klem, J; Kortelainen, M J; Lampén, T; Lassila-Perini, K; Lehti, S; Lindén, T; Luukka, P; Mäenpää, T; Nysten, J; Tuominen, E; Tuominiemi, J; Ungaro, D; Wendland, L; Banzuzi, K; Korpela, A; Tuuva, T; Nedelec, P; Sillou, D; Besancon, M; Chipaux, R; Dejardin, M; Denegri, D; Descamps, J; Fabbro, B; Faure, J L; Ferri, F; Ganjour, S; Gentit, F X; Givernaud, A; Gras, P; Hamel de Monchenault, G; Jarry, P; Lemaire, M C; Locci, E; Malcles, J; Marionneau, M; Millischer, L; Rander, J; Rosowsky, A; Rousseau, D; Titov, M; Verrecchia, P; Baffioni, S; Bianchini, L; Bluj, M; Busson, P; Charlot, C; Dobrzynski, L; Granier de Cassagnac, R; Haguenauer, M; Miné, P; Paganini, P; Sirois, Y; Thiebaux, C; Zabi, A; Agram, J L; Besson, A; Bloch, D; Bodin, D; Brom, J M; Conte, E; Drouhin, F; Fontaine, J C; Gelé, D; Goerlach, U; Gross, L; Juillot, P; Le Bihan, A C; Patois, Y; Speck, J; Van Hove, P; Baty, C; Bedjidian, M; Blaha, J; Boudoul, G; Brun, H; Chanon, N; Chierici, R; Contardo, D; Depasse, P; Dupasquier, T; El Mamouni, H; Fassi, F; Fay, J; Gascon, S; Ille, B; Kurca, T; Le Grand, T; Lethuillier, M; Lumb, N; Mirabito, L; Perries, S; Vander Donckt, M; Verdier, P; Djaoshvili, N; Roinishvili, N; Roinishvili, V; Amaglobeli, N; Adolphi, R; Anagnostou, G; Brauer, R; Braunschweig, W; Edelhoff, M; Esser, H; Feld, L; Karpinski, W; Khomich, A; Klein, K; Mohr, N; Ostaptchouk, A; Pandoulas, D; Pierschel, G; Raupach, F; Schael, S; Schultz von Dratzig, A; Schwering, G; Sprenger, D; Thomas, M; Weber, M; Wittmer, B; Wlochal, M; Actis, O; Altenhöfer, G; Bender, W; Biallass, P; Erdmann, M; Fetchenhauer, G; Frangenheim, J; Hebbeker, T; Hilgers, G; Hinzmann, A; Hoepfner, K; Hof, C; Kirsch, M; Klimkovich, T; Kreuzer, P; Lanske, D; Merschmeyer, M; Meyer, A; Philipps, B; Pieta, H; Reithler, H; Schmitz, S A; Sonnenschein, L; Sowa, M; Steggemann, J; Szczesny, H; Teyssier, D; Zeidler, C; Bontenackels, M; Davids, M; Duda, M; Flügge, G

    2010-01-01

    The performance of the Local Trigger based on the drift-tube system of the CMS experiment has been studied using muons from cosmic ray events collected during the commissioning of the detector in 2008. The properties of the system are extensively tested and compared with the simulation. The effect of the random arrival time of the cosmic rays on the trigger performance is reported, and the results are compared with the design expectations for proton-proton collisions and with previous measurements obtained with muon beams.

  8. Estimation and optimization of thermal performance of evacuated tube solar collector system

    Science.gov (United States)

    Dikmen, Erkan; Ayaz, Mahir; Ezen, H. Hüseyin; Küçüksille, Ecir U.; ?ahin, Arzu ?encan

    2014-05-01

    In this study, artificial neural networks (ANNs) and adaptive neuro-fuzzy (ANFIS) in order to predict the thermal performance of evacuated tube solar collector system have been used. The experimental data for the training and testing of the networks were used. The results of ANN are compared with ANFIS in which the same data sets are used. The R2-value for the thermal performance values of collector is 0.811914 which can be considered as satisfactory. The results obtained when unknown data were presented to the networks are satisfactory and indicate that the proposed method can successfully be used for the prediction of the thermal performance of evacuated tube solar collectors. In addition, new formulations obtained from ANN are presented for the calculation of the thermal performance. The advantages of this approaches compared to the conventional methods are speed, simplicity, and the capacity of the network to learn from examples. In addition, genetic algorithm (GA) was used to maximize the thermal performance of the system. The optimum working conditions of the system were determined by the GA.

  9. Elimination of plume in laser welding of small diameter tubes with YAG high performance laser

    International Nuclear Information System (INIS)

    Bushing technique is the practical method for repairing the damaged tubes of the steam generators in operation. In this case, a bush of smaller diameter is inserted in a small diameter tube. The damaged place is in the supporting plate and on tube walls, and the welding must be carried out in very narrow space. The authors developed a YAG high performance welding system with optical fibers of 2 kW. The 2 kW YAG laser oscillator is placed outside the safety container, and laser beam is transmitted through optical fibers to the end part, therefore, it is very important to protect the optical components from the damage by plume arising at an adjoining place of welding. First, the behavior of plume was studied in Ar, Nz and He atmosphere by using a 20 kW CO2 laser. The action of O2 concentration in protecting gas on penetration depth was examined. The welding condition for YAG laser welding, the condition of gas to help eliminate plume, and the results of practical application of this laser welding of bushes are reported. (K.I.)

  10. Study on heat transfer performance of an aluminum flat plate heat pipe with fins in vapor chamber

    International Nuclear Information System (INIS)

    Highlights: • A novel flat plate heat pipe (FPHP) was designed and performed. • Maximum HS temperature is lower than 60 °C when the heat load reaches 100 W. • The FPHP will spend less time to start up with the increase of heat flux. • Liquid FR and VD have a significant influence on thermal performance of FPHP. - Abstract: The heat transfer performance of a novel flat plate heat pipe (FPHP) for electronic cooling was investigated experimentally. A variety of performance tests of FPHP were carried out with different air flow velocities (1.5 m/s < u < 6 m/s), working fluid filling ratios (10% < FR < 50%), and the vacuum degrees (0.002 Pa < VD < 0.25 Pa). Using distilled water and acetone as working fluids, the influence of the above parameters on steady-state heat transfer characteristics of the FPHP was also examined. The experimental results indicated that the filling ratio and vacuum degree had a significant influence on thermal performance of FPHP. Compared with cooling performance using distilled water and acetone, the FPHP cooling component using acetone had a stronger heat dissipation capacity for the same filling ratio

  11. Study on the manufacturing process, causes of the pressure tube failure and methods for improving its performance

    International Nuclear Information System (INIS)

    Manufacturing processes of Zr-2.5Nb pressure tube used in CANDU reactor, effects of impurities on the properties of the pressure tube, experiences and causes of the pressure tube cracking accident and the development programs on the fuel channel at AECL have been described. Fabrication processes on the pressure tube have been explained in detail from the sponge production step to the final product. Test methods that are performed to verify the integrity of the final product have also been described. Most of the pressure tube rupture accidents were caused by DHC (Delayed Hydride Cracking). In cases of Pickering units 3 and 4 and Bruce unit 2, excessive residual stresses induced by improper rolled joint process had played a role to cause DHC. In Pickering unit 2, cracks formed by contact between pressure and calandria tubes due to the movement of garter spring were direct cause of failure. After the accidents, a lot of R and D programs on each component of the fuel channel have been carried out. The study on the improvement of manufacturing processes such as increasing cold working rate, performing the intermediate and final annealing and adding the third element like Fe, V, Cr for enhancing the pressure tube performance are on progress. To suppress hydrogen uptake into the pressure tube, the methods such as zirconia coating on the pressure tube, Cr-plating on the end fitting and placing the yttrium getter on the pressure tube are considered. Experiments on each test specimen are currently under way. Owing to such an effort, more advanced fuel channel can be installed in the next CANDU reactor. 6 tabs., 20 figs., 20 refs. (Author)

  12. Development and application of an efficient method for performing modal analysis of steam generator tubes in nuclear power plants

    International Nuclear Information System (INIS)

    A typical pressurized water reactor (PWR) steam generator has approximately 10,000 tubes. These tubes have different geometries, supporting conditions, and different material properties due to the non-uniform temperature distribution throughout the steam generator. Even though some tubes may have the same geometry and boundary conditions, the non-uniform distribution of coolant densities adjacent to the tubes causes them to have different added mass effects and dynamic characteristics. Therefore, for a reliable design of the steam generator, a separate modal analysis for each tube is necessary to perform the FIV (flow-induced vibration) analysis. However, the modal analysis of a tube including the finite element modeling is cumbersome and takes lots of time. And when a commercial finite element code is used, interfacing the modal analysis result, such as natural frequencies and mode shapes, with the FIV analysis procedure requires an additional significant amount of time and can possibly incur inadvertent error due to the complexity of data processing. It is therefore impossible to perform the complete FIV analysis for ten thousands of tubes when designing or maintaining a steam generator although it is necessary. Rather, to verify the safe design against the FIV, only a couple of tubes are chosen based on engineering judgment or past experience. In this paper, a computer program, PIAT-MODE, was developed which is able to perform modal analysis of all tubes of a PWR steam generator in a very efficient way. The geometries and boundary conditions of every tube were incorporated into PIAT-MODE using appropriate mathematical formulae. Material property data including the added mass effect was also included in the program. Once a specific tube is selected, the program automatically constructs the finite element model and generates the modal data very quickly. Therefore, modal analysis can be performed for every single tube in a straight way. When PIAT-MODE is coupled with the FIV analysis program, it gives an amazing benefit, which makes the FIV analysis of all tubes possible within a limited time during the design or maintenance period. Using the developed program, the stability ratio regarding the fluid-elastic instability and the amplitude of vibration resulting from the turbulence flow excitation can be calculated for all tubes according the standard ASME Code, therefore, much more reliable design of the steam generator against the FIV related failures can be achieved. For an operating plant, there is a requirement that every single tube must be quantitatively checked whether wear would be more than 40% in thickness during the next operation period. If yes, the tube must be plugged to prevent severe failure including the tube wall penetration. In order to decide the tube plugging, which leads the plant performance degradation, the wear prediction is required. The wear prediction analysis needs wear data by ultrasonic testing and modal property data of tubes. PIAT-MODE will be a power tool enabling the wear prediction in a limited maintenance period by supplying modal data for all tubes.

  13. The effects of area contraction on the performance of UNITEN's shock tube: Numerical study

    International Nuclear Information System (INIS)

    Numerical study into the effects of area contraction on shock tube performance has been reported in this paper. The shock tube is an important component of high speed fluid flow test facility was designed and built at the Universiti Tenaga Nasional (UNITEN). In the above mentioned facility, a small area contraction, in form of a bush, was placed adjacent to the diaphragm section to facilitate the diaphragm rupturing process when the pressure ratio across the diaphragm increases to a certain value. To investigate the effects of the small area contraction on facility performance, numerical simulations were conducted at different operating conditions (diaphragm pressure ratios P4/P1 of 10, 15, and 20). A two-dimensional time-accurate Navier-Stokes CFD solver was used to simulate the transient flow in the facility with and without area contraction. The numerical results show that the facility performance is influenced by area contraction in the diaphragm section. For instance, when operating the facility with area contraction using diaphragm pressure ratio (P4/P1) of 10, the shock wave strength and shock wave speed decrease by 18% and 8% respectively.

  14. Experimental Study of Convective Heat Transfer and Thermal Performance in the Heat-Sink Channel with Various Geometrical Configurations Fins

    OpenAIRE

    Mohit Taneja, 2 Sandeep Nandal, 3Arpan Manchanda, 4Ajay Kumar Agarwal

    2013-01-01

    An experimental study was conducted to investigate the heat transfer & friction loss characteristics in a heat sink channel with various geometrical configurations under constant heat flux conditions. The experiments are performed for the Reynolds number and heat flux in the ranges of 300 to 900 and 1.50-5.50kw/m2, respectively. The heat sink with two different channel heights and two different channel widths are accomplished. Different geometrical configurations parameters effect of the micr...

  15. Plastic Guidance Fins for Long Rod Projectiles .

    Directory of Open Access Journals (Sweden)

    Mark L. Bundy

    1997-10-01

    Full Text Available Projectile tail fins on long rod kinetic energy (KE penetrators serve the same purpose as fletchings (feathers on an arrow, namely, they help align the projectile axis with its velocity vector. This reduces the projectile's yaw and hence reduces its aerodynamic drag. In addition, a low yaw angle at target impact helps to maximise the projectile's target penetration. It is typical for projectiles to exit the gun muzzle and enter free flight at some ndn-zero yaw angle. Aerodynamic forces acting on yawed tail fins create a stabilising torque about the projectile's centre of gravity (CG. This torque can be increased by making the fin material lighter. Most conventional long rod penetrators fired from high performance guns have tail fins made from aluminium. However, aluminium can undergo catastrophic oxidation (rapid burning in-bore. Coating aluminium with Al/sub 2/O/sub 3/ {hardcoat prevents ignition of the substrate, provided solid propellant grain impacts do not chip the brittle hardcoat off the surface. Plastic is lighter than aluminium and less exothermic when oxidized. Therefore, other factors aside, it is conceivable that plastic fins could increase projectile stability while incurring less thermal erosion than aluminium. However, thermal loads are not the only concern when considering plastic as an alternative tail fin material. The mechanical strength of plastic is also a critical factor. This paper discusses some of the successes and failures of plastic fins, at least relatively thin fins, for use as KE stabilisers.

  16. Performance of a prototype aerogel counter readout by fine mesh photo-tubes

    International Nuclear Information System (INIS)

    The BABAR experiment, in order to achieve its physics program, requires pion/kaon identification capability up to 4.3 GeV/c. The recent development of new processes has lead to the fabrication of low density silica aerogel with high optical quality. An aerogel threshold counter using the combination of 2 refractive indices (1.055 and 1.007) can be used to complete the angular coverage of the particle identification system in the forward region of the BABAR experiment. We present final test-beam results on a 2 layer aerogel prototype, readout by Hamamatsu fine mesh photo-tubes, as required by the high magnetic field environment of the BaBar experiment. Several configurations have been tested, with different aerogels, photo-tubes and reflective materials. We have performed a Monte-Carlo simulation, in order to understand the sensitivity of light collection to the optical parameters. The result of the test shows that such a detector can achieve the desired performances. (authors). 14 refs., 19 figs., 1 tab

  17. Evaluation of diameter measurements performed on the casing and tubing of shaft 4 in the Asse pit

    International Nuclear Information System (INIS)

    Out-of-round of casing and tubing as observed so far, amounts to less than 3.1 mm in all instances with the greatest out-of-round values to be found at the deepest measurement horizon in the cover rock. In-situ examinations show that there is a slight torsion with casing and tubing in the salinary owing to construction. The article gives the results of ultrasonic wall-width measurements performed on the casing and tubing by means of the pulse-echo method. (DG)

  18. Research on the Pin Fin Efficiency and Structure

    OpenAIRE

    Fan Bailin; Huang Ganghan; Xu Long; Wang Yanjun; Zhang Pei

    2013-01-01

    The performance of pin fin heat sink can be to measure through the temperature field. The temperature field and efficiency of the Pin Fin were analyzed, Pin fin efficiency curve was drowned also the distribution of the temperature field along the length of the pin fin curve was drawn. Thermal resistance was composed by thermal resistance of Aluminum substrate? thermal resistance of convective heat transfer and the thermal resistance of the cooling liquid. The change rule was studied through t...

  19. Experimental Evaluation of the Energy Performance of an Air Vortex Tube when the Inlet Parameters are Varied

    OpenAIRE

    Torrella Alcaraz, Enrique; Patiño Pérez, Jorge; Sánchez García-Vacas, Daniel; Llopis Doménech, Rodrigo; Cabello López, Ramón

    2013-01-01

    he paper presents the analysis of the energy performance of an air vortex cooling tube under variations of the air inlet properties, with t hree independent experimental tests validated through the energy balance in the device. The experimental analysis includes the following variations of the input conditions: First, the effect of the air inlet pressure to the vortex tube, focused on the analysis of temperature variations in the output cold stream and in the coo...

  20. Simulation of the performance of shell-and-tube condensers; Rohrbuendelverfluessiger - Simulation des Leistungsverhaltens

    Energy Technology Data Exchange (ETDEWEB)

    Ciconkov, R. [Univ. ' ' St. Kiril and Metodij' ' , Masinski Fakultet, Skopje (Yugoslavia); Hilligweg, A. [Georg-Simon-Ohm-Fachhochschule Nuernberg, FB Maschinenbau und Versorgungstechnik (Germany)

    2003-02-01

    The performance of cold vapour refrigerating plants is depending on a multitude of parameters which directly influence a single component only. However, they have an indirect effect on all other components as well. To predict the balance point as a result of the interaction of all components it is necessary to predict the performance of each component separately. In this paper a simulation tool for shell-and-tube condensers is introduced, selected results are shown and explained. (orig.) [German] Kompressionskaelteanlagen sind im Betrieb vielfaeltigen Einfluessen unterworfen, die direkt auf einzelne Komponenten, indirekt aber auf die gesamte Anlage einwirken. Um den Betriebspunkt, der sich im Zusammenspiel der Komponenten einstellt, zu bestimmen, muss im ersten Schritt das Leistungsverhalten der einzelnen Komponenten dargestellt werden. In diesem Beitrag wird eine Methode zur Vorhersage des Leistungsverhaltens von Rohrbuendelverfluessigern erlaeutert. Einzelne Ergebnisse werden vorgestellt. (orig.)

  1. QuantiFERON-TB Gold In-Tube test performance in Denmark

    DEFF Research Database (Denmark)

    Hermansen, Thomas; Lillebaek, Troels

    2014-01-01

    BACKGROUND: Little is known about the QuantiFERON-TB Gold In-Tube Test (QFT) in extreme age groups. The test performance has been reported to be impaired in children and elderly, but reports are diverging. The aim of this study was to evaluate QFT performance in patients with and without Tuberculosis (TB). METHODS: A retrospective study analysing the results of 18,850 QFT performed in Denmark 2005-2010. The effect of age, sex, localisation of TB, and result of culture on QFT performance (positive, negative and indeterminate results) was determined. RESULTS: Among 383 patients with TB, indeterminate rate was low (3.9%, 15/383). Sensitivity was high (86.1%, 317/368) and not affected by sex or localization of TB disease, but declined with increasing age (p 65 years (8.1%, 219/2715) compared tothe adult population 15-64 years (4.5%, 552/12,317). Indeterminate results were due to a low positive control in 99.6% (801/804). CONCLUSION: In Denmark, a TB low incidence country, the overall QFT performance was good. The sensitivity in children (?1) was high although few children were included, whereas sensitivity declined with increasing age. Indeterminate rates were higher in infants and elderly. In contrast to current guidelines, our data suggest that the QFT performs well in children ?1 years in low endemic regions but that the test should be used with care among the elderly.

  2. QuantiFERON–TB Gold In-Tube test performance in Denmark

    DEFF Research Database (Denmark)

    Hermansen, Thomas; Lillebaek, Troels

    2014-01-01

    BACKGROUND: Little is known about the QuantiFERON-TB Gold In-Tube Test (QFT) in extreme age groups. The test performance has been reported to be impaired in children and elderly, but reports are diverging. The aim of this study was to evaluate QFT performance in patients with and without Tuberculosis (TB). METHODS: A retrospective study analysing the results of 18,850 QFT performed in Denmark 2005-2010. The effect of age, sex, localisation of TB, and result of culture on QFT performance (positive, negative and indeterminate results) was determined. RESULTS: Among 383 patients with TB, indeterminate rate was low (3.9%, 15/383). Sensitivity was high (86.1%, 317/368) and not affected by sex or localization of TB disease, but declined with increasing age (p 65 years (8.1%, 219/2715) compared to the adult population 15-64 years (4.5%, 552/12,317). Indeterminate results were due to a low positive control in 99.6% (801/804). CONCLUSION: In Denmark, a TB low incidence country, the overall QFT performance was good. The sensitivity in children (? 1) was high although few children were included, whereas sensitivity declined with increasing age. Indeterminate rates were higher in infants and elderly. In contrast to current guidelines, our data suggest that the QFT performs well in children ? 1 years in low endemic regions but that the test should be used with care among the elderly.

  3. Performance of a prototype aerogel counter readout by fine mesh photo-tubes

    International Nuclear Information System (INIS)

    The BaBar experiment, in order to achieve its physics program, requires pion/kaon identification capability up to 4.3 GeV/c. The recent development of new processes has lead to the fabrication of low density silica aerogel with high optical quality. An aerogel threshold counter using the combination of two refractive indices (1.055 and 1.007) can be used to complete the angular coverage of the particle identification system in the forward region of the BaBar experiment. We present final test-beam results on a two-layer aerogel prototype, readout by Hamamatsu fine mesh photo-tubes, as required by the high magnetic field environment of the BaBar experiment. Several configurations have been tested, with different aerogels, photo-tubes and reflective materials. A comparison between data and a detailed Monte Carlo simulation is also presented. The result of the test shows that such a detector can achieve the desired performances. (orig.)

  4. Enhancement of ECR performances by means of carbon nano-tubes based electron guns

    International Nuclear Information System (INIS)

    The CANTES experiment at INFN-LNS tested the use of carbon nano-tubes (CNTs) to emit electrons by field emission effect, in order to provide additional electrons to the plasma core of an ECR ion source. This technique was used with the Caesar source, demonstrating that the total extracted ion current is increased and that a relevant reduction of the number of 'high energy' electrons (above 100 keV) may be observed. The injection of additional electrons inside the plasma increases the amount of cold and warm electrons, and then the number of ionizing collisions. Details of the construction of CNTs based electron gun and of the improvement of performances of the Caesar ECR ion source will be presented. The paper is followed by the associated poster. (authors)

  5. Crash Performance Evaluation of Hydro-formed DP-steel Tubes Considering Welding Heat Effects, Formability and Spring-back

    International Nuclear Information System (INIS)

    In order to numerically evaluate hydro-formed DP-steel tubes on crash performance considering welding heat effects, finite element simulations of crash behavior were performed for hydro-formed tubes with and without heat treatment effects. Also, finite element simulations were performed for the sequential procedures of bending and hydro-forming of tubes in order to design process parameters, particularly for the boost condition and axial feeding, considering formability and spring-back. Effects of the material property including strain-rate sensitivity on formability as well as spring-back were also considered. The mechanical properties of the metal active gas (MAG) weld zone and the heat affected zone (HAZ) were obtained utilizing the continuous indentation method in this work

  6. Development of colburn ` j' factor and fanning friction factor ` f' correlations for compact heat exchanger plain fins by using CFD

    Science.gov (United States)

    Bala Sundar Rao, R.; Ranganath, G.; Ranganayakulu, C.

    2013-07-01

    A numerical model has been developed for plain fin of plate fin heat exchanger. Plain fin performance has been analyzed with the help of CFD by changing the various parameters of the fin, Colburn ` j' and fanning friction ` f' factors are calculated. These values compared with the standard values. The correlations have been developed between Reynolds number Re, fin height h, fin thickness t, fin spacing s, Colburn factor ` j' and friction factor ` f'.

  7. THERMAL ANALYSIS OF CPU WITH COMPOSITE PIN FIN HEAT SINKS

    Directory of Open Access Journals (Sweden)

    R.Mohan

    2010-09-01

    Full Text Available This paper describes about pin fin and slot parallel plate heat sinks with copper and carbon carbon composite(CCC base plate material mounted on CPU’s. The parameters such as fin geometry, base plate material, base plate thickness, number of fins, fin thickness are considered and primarily in this paper fin geometry, base platethicknesses, base plate materials are optimized for improving the thermal performance of a heat sink in the next generation. In this research work, the thermal model of the computer system with various fin geometry heat sink design has been selected and the fluid flow, thermal flow characteristics of heat sinks have been studied. The plate, pin and Elliptical fin geometry heat sinks have been used with base plate to enhance the heat dissipation. In this study a complete computer chassis with different heat sinks are investigated and the performances of the heat sinks are compared.

  8. Performance of Subsurface Tube Drainage System in Saline Soils: A Case Study

    Science.gov (United States)

    Pali, A. K.

    2015-06-01

    In order to improve the saline and water logged soils caused due to groundwater table rise, installation of subsurface drainage system is considered as one of the best remedies. However, the design of the drainage system has to be accurate so that the field performance results conform to the designed results. In this investigation, the field performance of subsurface tube drainage system installed at the study area was evaluated. The performance was evaluated on the basis of comparison of the designed value of water table drop as 30 cm after 2 days of drainage and predicted and field measured hydraulic heads for a consecutive drainage period of 14 days. The investigation revealed that the actual drop of water table after 2 days of drainage was 25 cm, about 17 % less than the designed value of 30 cm after 2 days of drainage. The comparison of hydraulic heads predicted by Van Schilfgaarde equation of unsteady drainage with the field-measured hydraulic heads showed that the deviation of predicted hydraulic heads varied within a range of ±8 % indicating high acceptability of Van Schlifgaarde equation for designing subsurface drainage system in saline and water logged soils resembling to that of the study area.

  9. Lightweight Radiator Fins for Space Nuclear Power Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase 1 project shall investigate concept radiator fins that incorporate novel carbon materials for improved performance of segmented high temperature...

  10. Pectoral fins and paternal quality in sticklebacks.

    Science.gov (United States)

    Künzler, R; Bakker, T C

    2000-01-01

    Sexual selection through female mate choice exerts a strong selection pressure on males' sexual traits, particularly when direct benefits are involved. In species with male parental care, one would expect sexual selection to favour paternal quality, for instance through selection on morphological structures which promote quality. We experimentally studied the influence of pectoral fins on paternal quality in male three-spined sticklebacks (Gasterosteus aculeatus L.). After reductions of fin area to different degrees, similar-sized males had to perform a complete reproductive cycle in enclosures in the field. The collected data on fanning behaviour and egg development showed that a reduction in pectoral fin size affected paternal quality probably through an increased beat frequency of the pectorals. Thus, pectoral fins can potentially signal paternal quality to choosy females. PMID:10874749

  11. Performance of a split-type air conditioner matched with coiled adiabatic capillary tubes using HCFC22 and HC290

    International Nuclear Information System (INIS)

    This paper experimentally investigated the system performance of a split-type air conditioner matching with different coiled adiabatic capillary tubes for HCFC22 and HC290. Experiments were carried out in a room-type calorimeter. The results have shown that (1) similar cooling effects can be achieved by matching various capillary tubes of different inner diameters; (2) parallel capillary tubes presented better system performance and flow stability with weaker inlet pressure fluctuations than the single capillary tube; (3) with the coil diameter of the capillary tube increasing from 40 mm to 120 mm, the mass flow rate tended to increase slightly. But the cooling capacity, input power and energy efficiency ratio (EER) did not show evident tendency of change; (4) the refrigerant charge and mass flow rate for HC290 were only 44% and 47% of that for HCFC22, respectively, due to the much lower density. And HC290 had 4.7-6.7% lower cooling capacity and 12.1-12.3% lower input power with respect to HCFC22. However, the EER of HC290 can be 8.5% higher than that of HCFC22, which exhibits the advantage of using HC290. In addition, the experimental uncertainties were analyzed and some application concerns of HC290 were discussed.

  12. Cooling performance assessment of horizontal earth tube system and effect on planting in tropical greenhouse

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • The cooling ability of HETS is studied for planting in tropical greenhouse. • The effective of system was moderate with COP more than 2.0. • Increasing diameter and air velocity increase COP more than other parameters. • The plant growth with HETS was significantly better than no-HETS plant. - Abstract: The benefit of geothermal energy is used by the horizontal earth tube system (HETS); which is not prevalent in tropical climate. This study evaluated geothermal cooling ability and parameters studied in Thailand by mathematical model. The measurement of the effect on plant cultivation was carried out in two identical greenhouses with 30 m2 of greenhouse volume. The HETS supplied cooled air to the model greenhouse (MGH), and the plant growth results were compared to the growth results of a conventional greenhouse (CGH). The prediction demonstrated that the coefficient of performance (COP) in clear sky day would be more than 2.0 while in the experiment it was found to be moderately lower. The parameters study could be useful for implementation of a system for maximum performance. Two plants Dahlias and head lettuce were grown satisfactory. The qualities of the plants with the HETS were better than the non-cooled plants. In addition, the quality of production was affected by variations of microclimate in the greenhouses and solar intensity throughout the cultivation period

  13. Study on the Performance of Inhibitors for a SCC of SG Tube Materials

    International Nuclear Information System (INIS)

    Steam generator (SG) tube materials have severe problems of a stress corrosion cracking (SCC) in nuclear power plants. Most of SCCs have occurred near the top of a sludge pile on a tubesheet and within a tube support plate crevice in which it is thought to be caustic. Some inhibitors have been studied to reduce the SCC problems for a SG tube. Laboratory tests using C-ring and constant extension rate specimens have shown that some chemical compounds may inhibit a SCC of a SG tube. Several titanium compounds have been applied at PWR type nuclear power plants. While they have reported some beneficial effects, there is insufficient evidence as yet that would convince us of its positive effects as an inhibitor. The objectives of this research are to investigate the inhibition effects of a SCC with a variation of SG tube materials and the penetration property in a crevice of the inhibitors

  14. An approach to optimal fin diameter based on entropy minimization

    Directory of Open Access Journals (Sweden)

    Masoud Asadi

    2013-04-01

    Full Text Available Pin fin geometries provide a large surface area of heat transfer and reduce the thermal resistance of the package. One of the important features of this type of fins is that they often take less space and contribute less to the weight and cost of the product. Pin fin arrays are used widely in many applications such as gas turbine or electronic circuits cooling, where pin fin geometries use due to their low cost of manufacturing and easy installing. In gas turbine application heat transfer from the blade to the coolant air can be increased by installing pin fins. In fact, Pin fin arrays increase heat transfer by increasing the flow turbulence and surface area of the airfoil exposed to the coolant. The overall performance of a heat exchanger with pin-fin typically depends on a number of parameters including the fin diameter, dimensions of the baseplate and pin-fins, thermal joint resistance and location heat sources. These parameters have an impact on the optimal design of a heat exchanger. Fin diameter is a key parameter to determine overall heat exchanger efficiency and entropy generation. In this paper, our objective is introducing an Equation to calculate optimal fin diameter based on minimizing entropy generation.

  15. Study of the performance of ATLAS muon drift-tube chambers in magntic fields and at high irradiation rates

    International Nuclear Information System (INIS)

    The performance of ATLAS muon drift-tube (MDT) chambers has been studied in detail using high-energy muon beams. The measurements of the drift tube properties in magnetic fields showed that inelastic collisions of the drifting electrons with the CO2 molecules in the Ar:CO2 (93:7) gas mixture of the MDT chambers have to be taken into account in the simulation of the drift properties. Such inelastic collisions are now correctly treated by the Garfield simulation programme from version 9 providing an accurate description of the behaviour of the ATLAS muon drift tubes, in particular in the magnetic field. Measurements at the Gamma Irradiation Facility at CERN were performed to study the performance of the MDT chambers in the presence of high ? ray background fluences. The chambers have a spatial resolution better than 40 ?m at the nominal background rates expected at the Large Hadron Collider design luminosity of 1034 cm-2s-1 and a resolution better than 50 ?m for up to five times higher background rates. Efficient muon detection up to background counting rates of 500 kHz per tube corresponding to 35% occupancy was demonstrated.

  16. Study of the performance of ATLAS muon drift-tube chambers in magntic fields and at high irradiation rates

    Energy Technology Data Exchange (ETDEWEB)

    Valderanis, Chrysostomos

    2012-07-26

    The performance of ATLAS muon drift-tube (MDT) chambers has been studied in detail using high-energy muon beams. The measurements of the drift tube properties in magnetic fields showed that inelastic collisions of the drifting electrons with the CO{sub 2} molecules in the Ar:CO{sub 2} (93:7) gas mixture of the MDT chambers have to be taken into account in the simulation of the drift properties. Such inelastic collisions are now correctly treated by the Garfield simulation programme from version 9 providing an accurate description of the behaviour of the ATLAS muon drift tubes, in particular in the magnetic field. Measurements at the Gamma Irradiation Facility at CERN were performed to study the performance of the MDT chambers in the presence of high {gamma} ray background fluences. The chambers have a spatial resolution better than 40 {mu}m at the nominal background rates expected at the Large Hadron Collider design luminosity of 10{sup 34} cm{sup -2}s{sup -1} and a resolution better than 50 {mu}m for up to five times higher background rates. Efficient muon detection up to background counting rates of 500 kHz per tube corresponding to 35% occupancy was demonstrated.

  17. The effect of elastic modulus and friction coefficient on rubber tube sealing performance

    Science.gov (United States)

    Li, Zhimiao; Xu, Siyuan; Ren, Fushen; Liu, Jubao

    2015-03-01

    The packer is the key element in separating geosphere layers of water injection, water plugging and fracturing operations in the oilfield. The sealing ability of the packer is depending on the contact pressure between rubber tube and the casing. The circumferential strain of casing wall was tested by the strain gauge to get the contact pressure distribution along axial direction of the tube. The friction force between the casing and the rubber tube was taken by the pressure sensor in compression process. Under the 20,60 and 100 degrees Celsius conditions, the friction forces and the contact pressure distribution were taken in work condition of single rubber tube, double rubber tubes and combination rubber tubes after oil immersion .The result shows that elastic modulus of rubber tube has little effect on the friction force and contact pressure. With elastic modulus decreasing, the friction forces has gradually decreasing trend; The friction coefficient has much impact on friction force: the friction forces under the condition of dry friction and wet friction are respectively equivalent to 48.27% and 5.38% axial compression forces. At wet friction condition, the contact pressure distribution is more uniform and the sealing effect is better.

  18. Final Technical Report - High-Performance, Oxide-Dispersion-Strengthened Tubes for Production of Ethylene adn Other Industrial Chemicals

    Energy Technology Data Exchange (ETDEWEB)

    McKimpson, Marvin G.

    2006-04-06

    This project was undertaken by Michigan Technological University and Special Metals Corporation to develop creep-resistant, coking-resistant oxide-dispersion-strengthened (ODS) tubes for use in industrial-scale ethylene pyrolysis and steam methane reforming operations. Ethylene pyrolysis tubes are exposed to some of the most severe service conditions for metallic materials found anywhere in the chemical process industries, including elevated temperatures, oxidizing atmospheres and high carbon potentials. During service, hard deposits of carbon (coke) build up on the inner wall of the tube, reducing heat transfer and restricting the flow of the hydrocarbon feedstocks. About every 20 to 60 days, the reactor must be taken off-line and decoked by burning out the accumulated carbon. This decoking costs on the order of $9 million per year per ethylene plant, accelerates tube degradation, and requires that tubes be replaced about every 5 years. The technology developed under this program seeks to reduce the energy and economic cost of coking by creating novel bimetallic tubes offering a combination of improved coking resistance, creep resistance and fabricability not available in current single-alloy tubes. The inner core of this tube consists of Incoloy(R) MA956, a commercial ferritic Fe-Cr-Al alloy offering a 50% reduction in coke buildup combined with improved carburization resistance. The outer sheath consists of a new material - oxide dispersion strengthened (ODS) Alloy 803(R) developed under the program. This new alloy retains the good fireside environmental resistance of Alloy 803, a commercial wrought alloy currently used for ethylene production, and provides an austenitic casing to alleviate the inherently-limited fabricability of the ferritic Incoloy(R) MA956 core. To provide mechanical compatibility between the two alloys and maximize creep resistance of the bimetallic tube, both the inner Incoloy(R) MA956 and the outer ODS Alloy 803 are oxide dispersion strengthened materials produced using mechanical alloying technology. To minimize cost, the bimetallic tube is produced by direct powder co-extrusion. This technology has potential for domestic energy savings of up to 4.1 trillion BTU/year (4.3 x 1015J/year) and a reduction of 370,000 tons (340,000 tonnes) of CO2 emissions in short-residence-time ethylene furnaces. This represents an energy savings and CO2 emissions reduction of about 3.3%. If the technology is also applied to other types of ethylene pyrolysis furnaces, total energy savings and CO2 emissions reductions could increase by up to five times. The work involved: Developing powder and consolidation processing protocols to produce an oxide-dispersion strengthened variant of Alloy 803 exhibiting creep strength comparable to Incoloy? Alloy MA956, Developing a direct powder co-extrusion protocol for fabricating co-extruded bimetallic Incoloy? Alloy MA956 / ODS Alloy 803 tubes, Characterizing the properties of the ODS Alloy 803 material, the welding characteristics of the bimetallic tubes, and the coking characteristics of the Incoloy? MA956 alloy, and Documenting the potential energy savings and user requirements for these bimetallic pyrolysis furnace tubes. The project demonstrated that oxide dispersion strengthened Alloy 803 can be produced successfully using conventional mechanical alloying technology. The oxide dispersion strengthened bimetallic radiant coil technology explored under this program has significant potential for energy savings and productivity improvements for domestic ethylene producers. In today's competitive market, however, domestic furnace manufacturers and ethylene producers appear reluctant to pay any cost premium for higher-performance coil materials offering either higher temperature capabilities or longer service life. Interest in oxide dispersion strengthened radiant coils is likely to increase if furnace and ethylene producers begin to focus more on increasing tube wall temperatures to improve productivity.

  19. Performance Evaluation of a Forced Convection Solar Drier with Evacuated Tube Collector for Drying Amla

    Directory of Open Access Journals (Sweden)

    AR. Umayal Sundari

    2013-06-01

    Full Text Available A forced convection solar drier is designed with evacuated tube collector and a blower. The performance of the designed drier is evaluated by carrying drying experiments at Thanjavur District, Tamilnadu, India with amla. Solar drying of amla is carried at different air velocity flow rates – 4m/s, 4.25m/s and 4.5m/s and is compared with natural sun drying. The temperature of the dryingchamber ranges from 53ºC to 82ºC while the ambient temperature ranges from 29ºC to 32ºC. The efficiency of the designed drier varies from 38.61% to 43.7% where as the efficiency of sun drying varies from 12.5% to 14.15%. It is observed that the efficiency of the drier increases with increase in air velocity flow rates. Initial moisture content of amla ranges between 83.6% and 84.3% and the equilibrium moisture content ranges between 0.1% and 0.6%. Solar drying takes 5 to 7 hours to reach safe moisture content where as sun drying takes 13 to15 hours. Also the quality of solar dried amla is better in terms of colour, odour, flavour and appearance than the sun dried amla. The observed result of the present work shows that the proposed solar drier is good for drying amla in this region.

  20. Experimental research on heat transfer performance of supercritical water in vertical tube

    International Nuclear Information System (INIS)

    Experimental research under supercritical pressure conditions was carried out on heat transfer performance in vertical tube of ?10 mm with a wide range of experimental parameters. The impacts of heat flux, mass flow rate and pressure on wall temperature and heat transfer coefficient were investigated. The experimental parameters are following: The pressures are 23, 25, 26 MPa, the mass flow rate range is 450 1200 kg/(m2·s), and the heat flux range is 200-1200 kW/m2. Experimental results indicate that the wall temperature gradually increases with the bulk temperature, and heat transfer enhancement exists near the critical temperature as the drastic changes in physical properties. The increase in heat flux and the decrease in mass flow rate reduce heat transfer enhancement and lead to deterioration of heat transfer. The main effects of pressure are reflected in the difference of heat flux and bulk temperature of the start point where heat transfer deterioration and enhancement occur. (authors)

  1. Thermal performance of direct-flow coaxial evacuated-tube solar collectors with and without a heat shield

    International Nuclear Information System (INIS)

    Graphical abstract: Collection efficiency plots and linear characterization of evacuated tube solar collector with a heat shield (ETC-HS) and evacuated tube solar collector without a heat shield (ETC-NHS). - Highlights: • Evacuated solar collector (ETC) with a heat shield had better thermal performance. • Efficiency of ETC with a heat shield is 54.70% at inlet temperature 123.9 °C. • 31.49% higher than efficiency of ETC without a heat shield at this temperature. • Heat loss coefficients of ETC with a heat shield was 1.86 W/(m2 K). • A 50.80% improvement in heat loss reduced compared to ETC without a heat shield. - Abstract: Experimental performance evaluation and comparative analyses based on heat extraction of direct-flow coaxial evacuated-tube solar collectors with and without heat shields are presented in this paper. A test system to evaluate the thermal performance of medium-temperature solar collectors was developed. The experimental analysis shows the evacuated-tube solar collector performed better with a heat shield, especially at higher working temperatures. The collection efficiency of the solar collector with a heat shield was 54.70% at the highest inlet temperature of 123.9 °C during the test period, which is 31.49% higher than for the solar collector without a heat shield. The calculated heat-loss coefficient for the evacuated-tube solar collector with a heat shield was 1.86 W/(m2 K), which is an improvement of 50.80% compared with that of the collector without a heat shield

  2. Modelisation, conception et simulation des performances d'un collecteur solaire aeraulique a tubes sous vide en milieu nordique

    Science.gov (United States)

    Paradis, Pierre-Luc

    The global energy consumption is still increasing year after year even if different initiatives are set up to decrease fossil fuel dependency. In Canada 80% of the energy is used for space heating and domestic hot water heating in residential sector. This heat could be provided by solar thermal technologies despite few difficulties originating from the cold climate. The aim of this project is to design a solar evacuated tube thermal collector using air as the working fluid. Firstly, needs and specifications of the product are established in a clear way. Then, three concepts of collector are presented. The first one relies on the standard evacuated tube. The second one uses a new technology of tubes; both sides are open. The third one uses heat pipe to extract the heat from the tubes. Based on the needs and specification as criteria, the concept involving tubes with both sides open has been selected as the best idea. In order to simulate the performances of the collector, a model of the heat exchanges in an evacuated tube was developed in 4 steps. The first step is a model in steady state intended to calculate the stagnation temperature of the tube for a fixed solar radiation, outside temperature and wind speed. As a second step, the model is generalised to transient condition in order to validate it with an experimental setup. A root mean square error of 2% is then calculated. The two remainder steps are intended to calculate the temperature of airflow leaving the tube. In the same way, a first model in steady state is developed and then generalised to the transient mode. Then, the validation with an experimental setup gave a difference of 0.2% for the root mean square error. Finally, a preindustrial prototype intended to work in open loop for preheating of fresh air is presented. During the project, explosion of the both sides open evacuated tube in overheating condition blocked the construction of a real prototype for the test. Different path for further work are also identified. One of these is in relation with CFD simulation of the uniformity of the airflow inside of the collector. Another one is the analysis of the design with a design of experiment plan.

  3. Visualization Study of the Effect of the Prolonged Vertical Tube on the Separation Performance of a Cyclone

    Science.gov (United States)

    Qian, Fuping; Zhang, Mingyao

    2007-06-01

    Cyclones have been widely used in different industrial processes. The most widely used experimental observation techniques for the flow pattern include Pitot tubes; hot-wire anemometers, as well as the non-intrusive techniques such as laser Doppler anemometry (LDA). However, all these available techniques have the limitation of only one-point measurement at a time, by which the whole-field fluid characterization in cyclones cannot be obtained simultaneously. Particle image velocimetry (PIV) is a novel non-intrusive visualization experimental technique to measure the whole-field three-dimensional fluid velocity instantaneously. However, only a few papers that examined the flow pattern in cyclones with PIV have been found. The objective of this work is to carry out an elementary experimental investigation of the effect of the prolonged vertical tube on the separation performance of a cyclone by PIV. Since the tangential velocity results in the centrifugal force for particle separation, and is regarded as the most important component of the gas flow in a cyclone, this paper only presents this velocity component. To facilitate visual observation all cyclone parts are constructed of perspex. The lengths of the prolonged vertical tube (attaching a vertical tube at the bottom of the dust outlet) are 0.30m, 0.40m and 0.50m, respectively. Experiments were conducted at 18m/s inlet gas velocity. The model cyclone is set horizontally in order to take images by charge coupled device (CCD) easily. Particles of about 1 ?m in diameter are added as tracer particles. They are generated by the atomizer. Air with tracer particles is sucked into the cyclone through the entry, subsequently travels through outlet tube of the cyclone and the gate valve, and is discharged into the atmosphere. The experimental results show that a typical Rankine vortex with inner quasi-forced vortex and outer quasi-free vortex in the vertical tube and dustbin which are the same as that in the body of the cyclone; the tangential velocity in the dustbin reduces1 greatly when the prolonged vertical tube attaching into the dust outlet, which can avoid the re-entrainment of already separated dust effectively. The results also indicate that PIV technique can be used to measure the strong swirl gas flow such as cyclones, and the prolonged vertical tube has practical significance for improving the separation performance of a cyclone.

  4. Room to high temperature measurements of flexible SOI FinFETs with sub-20-nm fins

    KAUST Repository

    Diab, Amer El Hajj

    2014-12-01

    We report the temperature dependence of the core electrical parameters and transport characteristics of a flexible version of fin field-effect transistor (FinFET) on silicon-on-insulator (SOI) with sub-20-nm wide fins and high-k/metal gate-stacks. For the first time, we characterize them from room to high temperature (150 °C) to show the impact of temperature variation on drain current, gate leakage current, and transconductance. Variation of extracted parameters, such as low-field mobility, subthreshold swing, threshold voltage, and ON-OFF current characteristics, is reported too. Direct comparison is made to a rigid version of the SOI FinFETs. The mobility degradation with temperature is mainly caused by phonon scattering mechanism. The overall excellent devices performance at high temperature after release is outlined proving the suitability of truly high-performance flexible inorganic electronics with such advanced architecture.

  5. Benchmarking the Performance of the ANSYS-FLUENT Standard k- ? Turbulence Model in Fluid Flow and Heat Transfer Predictions for Complex Flows around Circular Pin-Fins Using Various near Wall Functions

    Directory of Open Access Journals (Sweden)

    A. Al-Witry

    2013-05-01

    Full Text Available This study compares CFD analyses of the fluid flow and heat transfer phenomena in a popular pin-fin geometry of X/D = 2.5, S/D = 2.5 and H/D = 1 for a range of Re = 5,000 to 30,000 to those from experiment to aid in the benchmarking the performance of the CFD code FLUENT. The CFD analyses use three ANSYS-FLUENT (version 13 near wall treatments available within the code: 1 the Standard Wall Function (SWF, 2 the Non-Equilibrium Wall Function (NEWF and 3 the enhanced wall treatment. Experimental data used in this study were obtained from two papers: 1 by Chyu et al. (1998 for heat transfer predictions and another 2 by Metzgeret al. (1984 for pressure loss predictions, both for the same setup. The study also differentiates between the heat transfer occurring by the body of the pin-fin itself and that by the end-wall areas surrounding it. Results from the CFD analyses based on the fourth pin-fin from the inlet (commonly assumed to have a stable flow around it, show very good prediction accuracies of heat transfer coefficients for the pin-fin body itself but rather low accuracies for the end-wall areas (based on heat flux and inlet temperature values. Better accuracies were obtained when using the enhanced wall treatment where pin-fin body heat transfer coefficients were almost identical between the CFD and experimental results. An alternative definition of heat transfer based on the averaged local temperatures around the fourth pin-fin showed that the heat transfer coefficient then (with CFD's capability to establish the local thermal field is really between 1.5 to 3.5 times that predicted by using the inlet temperature in deducing the local h values. The same accuracies cannot be said about its predictions of pressure loss coefficients where CFD results tended to be lower by 50-100%h.

  6. Research on Under-actuated Flexible Pectoral Fin of Labriform Fish

    OpenAIRE

    Qiang Liu

    2012-01-01

    The new propulsor, whose inspiration is from pectoral fins of fishes, has arisen increasing attention. To improve the performance of the existing labriform bionic pectoral fin, based on the structure and control mechanism of real fish pectoral fin, the under-actuated technology was utilized to design a new flexible bionic pectoral fin. Then, the kinematic model of pectoral fin during fish forward steady swimming and the dynamic model of bionic pectoral was built. Finally, Matlab was used to s...

  7. Compound heat transfer enhancement for shell side of double-pipe heat exchanger by helical fins and vortex generators

    Science.gov (United States)

    Zhang, Li; Guo, Hongmei; Wu, Jianhua; Du, Wenjuan

    2012-07-01

    To improve heat transfer performance of shell side of double-pipe heat exchanger with helical fins on its inner tube, some vortex generators (VGs) were installed along the centerline of the helical channel. Heat transfer performance and pressure drop characteristic of the enhanced heat exchangers were investigated using air as the working fluid and steam as the heating medium. The helical fins were in the annulus and span its full width at different helical pitch. Wing-type VGs (delta or rectangular wing) and winglet-type VGs (delta or rectangular winglet pair) were used to combine with helical fins. The friction factor and Nusselt number can be well correlated by power-law correlations in the Reynolds number range studied. In order to evaluate the thermal performance of the shell side enhanced over the shell side without enhancement, comparisons were made under three constraints: (1) identical mass flow rate, IMF; (2) identical pressure drop, IPD and (3) identical pumping power, IPP. The results show the shell side enhanced by the compound heat transfer enhancement has better performance than the shell side only enhanced by helical fins at shorter helical pitch under the three constraints.

  8. EXPERIMENTAL HEAT TRANSFER ANALYSIS ON ANNULAR CIRCULAR AND ELLIPTICAL FINS .

    OpenAIRE

    N.Nagarani,; K.Mayilsamy

    2010-01-01

    Most of the engineering problems require high performance heat transfer components with progressively less weights, volumes, accommodating shapes and costs. Extended surfaces (fins) are one of the heat exchanging devices that are employed extensively to increase heat transfer rates. The rate of heat transfer depends on the surfacearea of the fin. Radial or annular fins are one of the most popular choices for exchanging the heat transfer rate from the primary surface of cylindrical shape. In t...

  9. High heat load test of CFC divertor target plate with screw tube for JT-60 superconducting modification

    International Nuclear Information System (INIS)

    A flat carbon fiber composite (CFC) tile mock-up with screw tubes, which have helical fins like a nut, was fabricated aiming at further improvement of the heat removal performance of the cost-effectively manufactured divert or target for JT-60SC (modified JT-60 as a superconducting coil tokamak). The heat removal performance of the mock-up was successfully demonstrated on the JAERI Electron Beam Irradiation Stand. The estimated heat transfer coefficient of the screw tube at the non-boiling region was roughly three times higher than that of the smooth tube. This corresponds to 1.5 times that of the swirl tube. A heat cycle test of 10 MW/m2 showed that the mock-up with the screw tubes could withstand for 1400-cycles. These results indicate that the divertor target plate with the flat CFC tile and the screw tube can be a promising candidate for the JT-60SC divertor target

  10. Experimental performance investigation of a shell and tube heat exchanger by exergy based sensitivity analysis

    Science.gov (United States)

    Mert, Suha Orçun; Reis, Alper

    2015-07-01

    Heat exchangers are used extensively in many industrial branches, primarily so in chemical and energy sectors. They also have important household usage as they are used in central and local heating systems. Any betterment on heat exchangers will serve greatly in preserving our already dwindling and costly energy resources. Strong approach of exergy analysis -which helps find out where the first steps should be taken in determining sources of inefficiencies and how to remedy them- will be used as a means to this end. The maximum useful work that can be harnessed from systems relationships with its environment is defined as exergy. In this study, the inlet and outlet flow rate values of fluids and temperature of hot stream both on shell and tube parts of a shell-tube heat exchange system have been inspected and their effects on the exergy efficiency of this thermal system have been analyzed. It is seen that the combination of high tube side inlet temperature, low shell side flow rate and high tube side flow rate are found to be the optimum for this experimental system with reaching 75, 65, and 32 % efficiencies respectively. Selecting operating conditions suitable to this behavior will help to increase the overall efficiency of shell-tube heat exchange systems and cause an increment in energy conservation.

  11. Heat transfer in banks of tubes in crossflow

    International Nuclear Information System (INIS)

    This volume examines heat transfer, resistance, and characteristics of flow across banks of smooth, rough, and finned tubes over a wide range of parameters. The studies comprising the work are complemented by additional material on local and average heat transfer for in-line and staggered banks of tubes, and determination of optimal pitch, roughness parameters, finning, and effectiveness

  12. An Evaluation of Performance Metrics for High Efficiency Tube-and-Wing Aircraft Entering Service in 2030 to 2035

    Science.gov (United States)

    Perkins, H. Douglas; Wilson, Jack; Raymer, Daniel P.

    2011-01-01

    An analysis of basic vehicle characteristics required to meet the Fundamental Aeronautics Program s 70 percent energy consumption reduction goal for commercial airliners in the 2030 to 2035 timeframe was conducted. A total of 29 combinations of vehicle parasitic drag coefficient, vehicle induced drag coefficient, vehicle empty weight and engine Specific Fuel Consumption were used to create sized tube-and-wing vehicle models. The mission fuel burn for each of these sized vehicles was then compared to a baseline current technology vehicle. A response surface equation was generated of fuel burn reduction as a function of the four basic vehicle performance metrics, so that any values of the performance metrics up to a 50 percent reduction could be used to estimate fuel burn reduction of tube-and-wing aircraft for future studies.

  13. Sensitization and performances of S1 image converter tubes designed for laser fusion experiments

    International Nuclear Information System (INIS)

    S1 streak cameras with time resolution better than 10 ps are now currently available at the Centre d'Etudes de Limeil. They integrate a standard P 500 image converter tube slightly modified to allow the S1 photocathode's deposition. Almost 70% of the tubes have 1.06 ?m sensitivity greater than 50 ?A/w and 60% are in the 100 to 400 ?A/w range. It is also possible to regenerate the 1.06 ?m sensitivity when necessary, thus solving the difficult lifetime problem of these tubes. Dynamic range of a few hundreds is possible for 47 ps I.R. laser pulses and more than 64 for 12 ps pulses

  14. Hydrothermal Preparation of Gd3+Doped Titanate Nano tubes: Magnetic Properties and Photovoltaic Performance

    International Nuclear Information System (INIS)

    Pure and Gd3+ doped titanate nano tubes (TNTs) materials were synthesized by a hydrothermal method. Their morphology, optical properties, thermal stability, and magnetic properties were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), UV-Vis spectroscopy, thermal analysis, and magnetic measurements. It was found that doping renders Gd3+ TNT visible light active and results in smaller crystallite size and larger surface area as well as higher thermal stability compared to pure titanate nano tubes. The estimated magnetic moments point to presence of weak antiferromagnetic interaction. Application of the prepared Gd3+ TNT for modifying conventional photoanodes in polymer solar cells was attempted. Preliminary results show slightly improved photovoltaic energy conversion efficiency in the devices containing the newly designed Gd3+ doped nano tubes.

  15. A Three Dimensional Performance Analysis of a Developed Evacuated Tube Collector using a CFD Fluent Solar Load Model

    OpenAIRE

    Ali Basil. H.; Gilani S. I.; Al-Kayiem Hussain H.

    2014-01-01

    For the flow through type selected geometry of the designed evacuated tube collector ETC, a three dimensional simulation and analysis of the thermal performance was done, using the ray-tracing solar load model provided by the ANSYS-FLUENT software. In this model the solar radiation heat flux is solved using fair weather condition radiation equations, and then solar radiation load is considered as a heat source term in the energy equation. The thermal effects of the fluid flow and heat transfe...

  16. The Waveform Digitiser of the Double Chooz Experiment: Performance and Quantisation Effects on PhotoMultiplier Tube Signals

    OpenAIRE

    Abe, Y.; Akiri, T.; Cabrera, A.; Courty, B.; Dawson, J. V.; Gonzalez, L. F. G.; Hourlier, A.(AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cité, 75205, Paris Cedex 13, France); Ishitsuka, M.; De Kerret, H.; Kryn, D.; Novella, P.; Obolensky, M.(AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cité, 75205, Paris Cedex 13, France); Perasso, S.(AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cité, 75205, Paris Cedex 13, France); Remoto, A.; Roncin, R.(AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cité, 75205, Paris Cedex 13, France)

    2013-01-01

    We present the waveform digitiser used in the Double Chooz experiment. We describe the hardware and the custom-built firmware specifically developed for the experiment. The performance of the device is tested with regards to digitising low light level signals from photomultiplier tubes and measuring pulse charge. This highlights the role of quantisation effects and leads to some general recommendations on the design and use of waveform digitisers.

  17. Development of Remote Weld Testing Technique for Moisture Separator and Reheater Tubes in Nuclear Power Plants

    International Nuclear Information System (INIS)

    The heat exchanger tube in nuclear power plants is mainly fabricated from nonferromagnetic material such as a copper, titanium, and inconel alloy, but the moisture separator and reheater tube in the turbine system is fabricated from ferromagnetic material such as a carbon steel or ferrite stainless steel which has a good mechanical properties in harsh environments of high pressure and temperature. Especially, the moisture separator and reheater tubes, which use steam as a heat transfer media, typically employ a tubing with integral fins to furnish higher heat transfer rates. The ferromagnetic tube typically shows superior properties in high pressure and temperature environments than a nonferromagnetic material, but can make a trouble during the normal operation of power plants because the ferrous tube has service-induced damage forms including a steam cutting, erosion, mechanical wear, stress corrosion cracking, etc. Therefore, nondestructive examination is periodically performed to evaluate the tube integrity. Now, the remote field testing(RFT) technique is one of the solution for examination of ferromagnetic tube because the conventional eddy current technique typically can not be applied to ferromagnetic tube such as a ferrite stainless steel due to the high electrical permeability of ferrous tube. In this study, we have designed RFT probes, calibration standards, artificial flaw specimen, and probe pusher-puller necessary for field application, and have successfully carry out RFT examination of the moisture separator and reheater tube of nuclear power plants.

  18. Research on Under-actuated Flexible Pectoral Fin of Labriform Fish

    Directory of Open Access Journals (Sweden)

    Qiang Liu

    2012-06-01

    Full Text Available The new propulsor, whose inspiration is from pectoral fins of fishes, has arisen increasing attention. To improve the performance of the existing labriform bionic pectoral fin, based on the structure and control mechanism of real fish pectoral fin, the under-actuated technology was utilized to design a new flexible bionic pectoral fin. Then, the kinematic model of pectoral fin during fish forward steady swimming and the dynamic model of bionic pectoral was built. Finally, Matlab was used to simulate the kinematic and dynamic performance of bionic pectoral fin. The simulation result shows that the new flexible bionic pectoral fin can imitate the propulsion motion morphology of pectoral fin during fish forward steady swimming well. However, due to the restriction of kinematic model of pectoral fin and structure as well as physical properties of bionic fin ray, there is still tolerance between the locomotion morphology of bionic pectoral fin and that of real fish. Therefore, it is necessary to develop further research on kinematic modeling of pectoral fin and bionic design of fin ray. Additionally, the new bionic pectoral fin reduces the number of the driving variables, providing the possibility and the basis of further reducing the volume as well as the complexity of bionic device of pectoral fin.

  19. Thermal performance of an integrated collector storage solar water heater (ICSSWH) with a storage tank equipped with radial fins of rectangular profile

    Science.gov (United States)

    Chaabane, Monia; Mhiri, Hatem; Bournot, Philippe

    2013-01-01

    The thermal behavior of an integrated collector storage solar water heater (ICSSWH) is numerically studied using the package Fluent 6.3. Based on the good agreement between the numerical results and the experimental data of Chaouachi and Gabsi (Renew Energy Revue 9(2):75-82, 2006), an attempt to improve this solar system operating was made by equipping the storage tank with radial fins of rectangular profile. A second 3D CFD model was developed and a series of numerical simulations were conducted for various SWH designs which differ in the depth of this extended surface for heat exchange. As the modified surface presents a higher characteristic length for convective heat transfer from the storage tank to the water, the fins equipped storage tank based SWH is determined to have a higher water temperature and a reduced thermal losses coefficient during the day-time period. Regarding the night operating of this water heater, the results suggest that the modified system presents higher thermal losses.

  20. [Toxicity of puffer fish fins].

    Science.gov (United States)

    Honda, Shunichi; Ichimaru, Shunichi; Arakawa, Osamu; Takatani, Tomohiro; Noguchi, Tamao; Ishizaki, Shoichiro; Nagashima, Yuji

    2007-10-01

    Puffer fish is prized as a Japanese traditional food and its fin is also used in the cuisine. However, whether the fin is edible or not is determined for convenience from the toxicity of skin, since little information is available about the toxicity of puffer fish fins. In the present study, we examined the toxicity of fins and skin of three toxic species, Takifugu vermicularis, T. snyderi, and T. porphyreus. The toxicity of T. vermicularis fins (< 5-52.4 MU/g) was significantly lower than that of skin (<5-1200 MU/g). HPLC analysis showed that tetrodotoxin was a major toxic principle irrespective of the toxicity value in each tissue of T. vermicularis. In the case of T. snyderi and T. porphyreus, the toxicity of fins was at almost the same level as that of the skin. The toxicity (< 10-12 MU/g) of caudal fins of T. porphyreus was apparently increased to 16.5-22.0 MU/g by drying. However, the toxin amounts in the dried fins were slightly decreased as compared with those of the non-dried fins. These results demonstrate that puffer fish with toxic skin also have toxic fins. PMID:18027550

  1. DEVELOPMENT OF A REPRODUCIBLE SCREENING METHOD TO DETERMINE THE MECHANISM AND EFFECT OF ORGANIC ACIDS AND OTHER CONTAMINANTS ON THE CORROSION OF ALUMINUM-FINNED COPPER-TUBE HEAT EXCHANGE COILS

    Energy Technology Data Exchange (ETDEWEB)

    Richard A. Corbett; Dave Severance

    2005-02-01

    Formicary corrosion is an insidious form of localized pitting corrosion. Notoya (1997b) wrote, ?In Japan, this type of corrosion is found in approximately 10% of cases of premature failure of copper tubes.? Attack characteristically features very small surface pits which are not visible to the un-aided eye, and random directional changes in the underlying copper metal. Attack is rapid. Failures have occurred before installation, shortly thereafter, or within several years later. Objectives of this Research Project Conduct an in depth literature search on the subject of formicary corrosion. Define the corrosion mechanism. Develop a test method that will reproduce formicary corrosion. Develop a test method for screening candidate materials that could cause formicary corrosion.

  2. Enhancement of the Remote Field Eddy Current Testing Performed from Outside of a Magnetic Tube

    Directory of Open Access Journals (Sweden)

    Tomas Marek

    2006-01-01

    Full Text Available The paper deals with design of remote field eddy current probe for non-destructive testing dedicated for inspection of ferromagnetic tubular material from outside. The remote field effect inside the tube wall is achieved by the medium of a magnetic shield covering the probe. Results of numeric simulations made for verification of probe characteristics confirmed the effectiveness of probe design.

  3. In-pile performance of a double-walled tube and a tritium permeation barrier

    Energy Technology Data Exchange (ETDEWEB)

    Magielsen, A.J. E-mail: magielsen@nrg-nl.com; Bakker, K.; Chabrol, C.; Conrad, R.; Laan, J.G. van der; Rigal, E.; Stijkel, M.P

    2002-12-01

    In two recent irradiation experiments in the HFR Petten, tritium permeation rates through representative materials to be used as cooling tubes of the water-cooled lithium-lead blanket have been measured in-pile. These latest experiments in the EXOTIC 8 series (E 8.9 and E 8.10) are made of a double wall tube (DWT) and a T91 tube with an Fe-Al/Al{sub 2}O{sub 3} layer acting as tritium permeation barrier (TPB). These tubes contain annular pebble beds of ceramic breeder materials for the helium-cooled pebble bed concept blanket as tritium breeding material. Both experiments are built up of two concentric and independently purged containments allowing on-line tritium release rate and permeation rate measurements. In-pile operation has ended in March 2001 after 450 full power days and resulted in an irradiation damage of approximately 2.6 and 3.2 dpa, respectively in T91 steel. This paper reports on the experimental results obtained for in-pile tritium permeation and discusses the influence of purge gas compositions, temperature and irradiation on tritium permeation through the DWT and TPB.

  4. In-pile performance of a double-walled tube and a tritium permeation barrier

    International Nuclear Information System (INIS)

    In two recent irradiation experiments in the HFR Petten, tritium permeation rates through representative materials to be used as cooling tubes of the water-cooled lithium-lead blanket have been measured in-pile. These latest experiments in the EXOTIC 8 series (E 8.9 and E 8.10) are made of a double wall tube (DWT) and a T91 tube with an Fe-Al/Al2O3 layer acting as tritium permeation barrier (TPB). These tubes contain annular pebble beds of ceramic breeder materials for the helium-cooled pebble bed concept blanket as tritium breeding material. Both experiments are built up of two concentric and independently purged containments allowing on-line tritium release rate and permeation rate measurements. In-pile operation has ended in March 2001 after 450 full power days and resulted in an irradiation damage of approximately 2.6 and 3.2 dpa, respectively in T91 steel. This paper reports on the experimental results obtained for in-pile tritium permeation and discusses the influence of purge gas compositions, temperature and irradiation on tritium permeation through the DWT and TPB

  5. Design and performance of a charge-coupled device /CCD/-streak tube

    International Nuclear Information System (INIS)

    A new 'streak' tube has been developed for use in diagnostic applications involving very high-speed optical transients such as the Shiva laser-fusion studies at the University of California's Lawrence Livermore Laboratory. The tube combines the direct read-out characteristics of a CCD (charge-coupled device) with the high-speed deflection system incorporated in the light-shutter image tube to give immediate electronic read-out of information suitable for data processing. The front section of the tube is an image-intensifier stage with an infrared-sensitive photocathode (S-1) sensitive to the laser wavelength of 1.06 micrometers. When the laser beam is incident on the photocathode, the emitted stream of electrons is accelerated and deflected by a ramp voltage applied to deflecting electrodes. The deflected beam impacts the CCD, producing several thousand electron-hole pairs per photoelectron. The charge pattern is then scanned out providing a time-intensity profile of the laser beam

  6. Benchmarking the Performance of the ANSYS-FLUENT Standard k- ? Turbulence Model in Fluid Flow and Heat Transfer Predictions for Complex Flows around Circular Pin-Fins Using Various near Wall Functions

    OpenAIRE

    A. Al-Witry; M. Es-Saheb

    2013-01-01

    This study compares CFD analyses of the fluid flow and heat transfer phenomena in a popular pin-fin geometry of X/D = 2.5, S/D = 2.5 and H/D = 1 for a range of Re = 5,000 to 30,000 to those from experiment to aid in the benchmarking the performance of the CFD code FLUENT. The CFD analyses use three ANSYS-FLUENT (version 13) near wall treatments available within the code: 1) the Standard Wall Function (SWF), 2) the Non-Equilibrium Wall Function (NEWF) and 3) the enhanced wall treatment. Experi...

  7. A minichannel aluminium tube heat exchanger - Pt. 2: Evaporator performance with propane

    Energy Technology Data Exchange (ETDEWEB)

    Fernando, Primal; Palm, Bjoern; Ameel, Tim; Lundqvist, Per; Granryd, Eric [Department of Energy Technology, Division of Applied Thermodynamics and Refrigeration, Royal Institute of Technology (KTH), SE-100 44 Stockholm (Sweden)

    2008-06-15

    This paper presents heat transfer data for a multiport minichannel heat exchanger vertically mounted as an evaporator in a test-rig simulating a small water-to-water heat pump. The multiport minichannel heat exchanger was designed similar to a shell-and-tube type heat exchanger, with a six-channel tube of 1.42 mm hydraulic diameter, a tube-side heat transfer area of 0.777 m{sup 2} and a shell-side heat transfer area of 0.815 m{sup 2}. Refrigerant propane with a desired vapour quality flowed upward through the tubes and exited with a desired superheat of 1-4 K. A temperature-controlled glycol solution that flowed downward on the shell-side supplied the heat for the evaporation of the propane. The heat transfer rate between the glycol solution and propane was controlled by varying the evaporation temperature and propane mass flow rate while the glycol flow rate was fixed (18.50 l min{sup -1}). Tests were conducted for a range of evaporation temperatures from -15 to +10{sup o}C, heat flux from 2000 to 9000 W m{sup -2} and mass flux from 13 to 66 kg m{sup -2} s{sup -1}. The heat transfer coefficients were compared with 14 correlations found in the literature. The experimental heat transfer coefficients were higher than those predicted by many of the correlations. A correlation which was previously developed for a very large and long tube (21 mm diameter and 10 m long) was in good agreement with the experimental data (97% of the data within {+-}30%). Several other correlations were able to predict the data within a reasonable deviation (within {+-}30%) after some adjustments to the correlations. (author)

  8. Assessment of Blasting Performance Using Electronic Vis-à-Vis Shock Tube Detonators in Strong Garnet Biotite Sillimanite Gneiss Formations

    Science.gov (United States)

    Sharma, Suresh Kumar; Rai, Piyush

    2015-05-01

    This paper presents a comparative investigation of the shock tube and electronic detonating systems practised in bench blasting. The blast trials were conducted on overburden rocks of Garnet Biotite Sillimanite Gneiss formations in one of the largest metalliferous mine of India. The study revealed that the choice of detonating system was crucial in deciding the fragment size and its distribution within the blasted muck-piles. The fragment size and its distribution affected the digging rate of excavators. Also, the shape of the blasted muck-pile was found to be related to the degree of fragmentation. From the present work, it may be inferred that in electronic detonation system, timely release of explosive energy resulted in better overall blasting performance. Hence, the precision in delay time must be considered in designing blast rounds in such overburden rock formations. State-of-art image analysis, GPS based muck-pile profile plotting techniques were rigorously used in the investigation. The study revealed that a mean fragment size (K50) value for shock tube detonated blasts (0.55-0.59 m) was higher than that of electronically detonated blasts (0.43-0.45 m). The digging rate of designated shovels (34 m3) with electronically detonated blasts was consistently more than 5000 t/h, which was almost 13 % higher in comparison to shock tube detonated blasts. Furthermore, favourable muck-pile shapes were witnessed in electronically detonated blasts from the observations made on the dozer performance.

  9. Ear Tubes

    Science.gov (United States)

    ... Ear tubes are inserted through an outpatient surgical procedure called a myringotomy. A myringotomy refers to an incision (small hole) ... and adults may be able to tolerate the procedure without anesthetic. A myringotomy is performed and the fluid behind the ear ...

  10. Performance Analysis of Shell and Tube Heat Exchanger Using Miscible System

    Directory of Open Access Journals (Sweden)

    M. Thirumarimurugan

    2008-01-01

    Full Text Available An experimental investigation on comparative heat transfer study on a solvent and solution were made using 1-1 Shell and Tube Heat Exchanger. Steam is the hot fluid, whereas Water and Acetic acid-Water miscible solution serves as cold fluid. A series of runs were made between steam and water, steam and Acetic acid solution. In addition to, the volume fraction of Acetic acid was varied and the experiment was held. The flow rate of the cold fluid is maintained from 120 to 720 lph and the volume fraction of Acetic acid is varied from 10-50%. Experimental results such as exchanger effectiveness, overall heat transfer coefficients were calculated. A mathematical model was developed for the outlet temperatures of both the Shell and Tube side fluids and was simulated using MATLAB program. The model was compared with the experimental findings and found to be valid.

  11. Controlled Thermal-Mechanical Processing of Tubes and Pipes for Enhanced Manufacturing and Performance

    Energy Technology Data Exchange (ETDEWEB)

    Kolarik, Robert V.

    2005-11-11

    The Alloy Steel Business of The Timken Company won an award for the controlled thermo-mechanical processing (CTMP) project and assembled a strong international public/private partnership to execute the project. The premise of the CTMP work was to combine Timken's product understanding with its process expertise and knowledge of metallurgical and deformation fundamentals developed during the project to build a predictive process design capability. The CTMP effort succeeded in delivering a pc-based capability in the tube optimization model, with a virtual pilot plant (VPP) feature to represent the desired tube making process to predict the resultant microstructure tailored for the desired application. Additional tasks included a system for direct, online measurement of grain size and demonstration of application of CTMP via robotically enhanced manufacturing.

  12. The dependency of different stress-level SiN capping films and the optimization of D-SMT process for the device performance booster in Ge n-FinFETs

    Science.gov (United States)

    Liao, M.-H.; Chen, P.-G.

    2015-08-01

    The capping stressed SiN film is one of the most important process steps for the dislocation stress memorization technique (D-SMT), which has been used widely in the current industry, for the electron mobility booster in the n-type transistor beyond the 32/28 nm technology node. In this work, we found that the different stress-level SiN capping films influence the crystal re-growth velocities along different directions including [100] and [110] directions in Ge a lot. It can be further used to optimize the dislocation angle in the transistor during the D-SMT process and then results in the largest channel stress distribution to boost the device performance in the Ge n-FinFETs. Based on the theoretical calculation and experimental demonstration, it shows that the Ge three dimensional (3D) n-FinFETs device performance is improved ˜55% with the usage of +3 GPa tensile stressed SiN capping film. The channel stress and dislocation angle is ˜2.5 GPa and 30°, measured by the atomic force microscope-Raman technique and transmission electron microscopy, respectively.

  13. Toward quantum FinFET

    CERN Document Server

    Wang, Zhiming

    2013-01-01

    This book reviews a range of quantum phenomena in novel nanoscale transistors called FinFETs, including quantized conductance of 1D transport, single electron effect, tunneling transport, etc. The goal is to create a fundamental bridge between quantum FinFET and nanotechnology to stimulate readers' interest in developing new types of semiconductor technology. Although the rapid development of micro-nano fabrication is driving the MOSFET downscaling trend that is evolving from planar channel to nonplanar FinFET, silicon-based CMOS technology is expected to face fundamental limits in the near future. Therefore, new types of nanoscale devices are being investigated aggressively to take advantage of the quantum effect in carrier transport. The quantum confinement effect of FinFET at room temperatures was reported following the breakthrough to sub-10nm scale technology in silicon nanowires. With chapters written by leading scientists throughout the world, Toward Quantum FinFET provides a comprehensive introductio...

  14. PERFORMANCE OF EVACUATED TUBE SOLAR COLLECTOR USING WATER-BASED TITANIUM OXIDE NANOFLUID

    OpenAIRE

    M. Mahendran; Lee, G. C.; Sharma, K V; A. Shahrani; R. A. Bakar

    2012-01-01

    Experiments are undertaken to determine the efficiency of an evacuated tube solar collector using water-based Titanium Oxide (TiO2) nanofluid at the Pekan Campus (3?32’ N, 103?25’ E), Faculty of Mechanical Engineering, University Malaysia Pahang, for the conversion of solar thermal energy. Malaysia lies in the equatorial zone with an average daily solar insolation of more than 900 W/m², which can reach a maximum of 1200 W/m² for most of the year. Traditionally water is pumped through the coll...

  15. Feasibility study to perform coiled tubing drilling on Gullfaks-A

    OpenAIRE

    Albawi, Ahmed Haimet

    2013-01-01

    This report is carried out as part of Decision gate1 (DG1) feasibility study conducted for the possibility of commencing coiled tubing drilling to drill slim holes simultaneously with other drilling activities on Gullfaks A (GF-A). A number of wells on GF-A platform has been closed and experienced oil production drop due to different reasons. However there are still small reservoirs with oil left in place which can be drilled through their mother wells to act as producer or injector wells in ...

  16. Construction and performance of a 2.7 m long straw drift tube prototype chamber for the SSC

    International Nuclear Information System (INIS)

    We report the construction and testing of a 2.7 m long straw tube drift chamber consisting of 60 channels. The straw tubes with 2 mm radius are stacked in a pyramid shape up to eight tube layers. There are two wire supports inside each tube for electrostatic stability. 28 tubes out of 60 are instrumented for measurement of resolution, gas gain, and attentuation length. Resolution of close to 110 ?m and attenuaion length of 500 cm are obtained. (orig.)

  17. 50 CFR 600.1204 - Shark finning; possession at sea and landing of shark fins.

    Science.gov (United States)

    2010-10-01

    ...2010-10-01 2010-10-01 false Shark finning; possession at sea and landing of shark fins...COMMERCE MAGNUSON-STEVENS ACT PROVISIONS Shark Finning § 600.1204 Shark finning; possession at sea and landing of shark...

  18. A preliminary study into performing routine tube output and automatic exposure control quality assurance using radiology information system data

    International Nuclear Information System (INIS)

    Data are currently being collected from hospital radiology information systems in the North West of the UK for the purposes of both clinical audit and patient dose audit. Could these data also be used to satisfy quality assurance (QA) requirements according to UK guidance? From 2008 to 2009, 731 653 records were submitted from 8 hospitals from the North West England. For automatic exposure control QA, the protocol from Inst. of Physics and Engineering in Medicine (IPEM) report 91 recommends that milli amperes per second can be monitored for repeatability and reproducibility using a suitable phantom, at 70-81 kV. Abdomen AP and chest PA examinations were analysed to find the most common kilo voltage used with these records then used to plot average monthly milli amperes per second with time. IPEM report 91 also recommends that a range of commonly used clinical settings is used to check output reproducibility and repeatability. For each tube, the dose area product values were plotted over time for two most common exposure factor sets. Results show that it is possible to do performance checks of AEC systems; however more work is required to be able to monitor tube output performance. Procedurally, the management system requires work and the benefits to the workflow would need to be demonstrated. (authors)

  19. Finned Carbon-Carbon Heat Pipe with Potassium Working Fluid

    Science.gov (United States)

    Juhasz, Albert J.

    2010-01-01

    This elemental space radiator heat pipe is designed to operate in the 700 to 875 K temperature range. It consists of a C-C (carbon-carbon) shell made from poly-acrylonitride fibers that are woven in an angle interlock pattern and densified with pitch at high process temperature with integrally woven fins. The fins are 2.5 cm long and 1 mm thick, and provide an extended radiating surface at the colder condenser section of the heat pipe. The weave pattern features a continuous fiber bath from the inner tube surface to the outside edges of the fins to maximize the thermal conductance, and to thus minimize the temperature drop at the condenser end. The heat pipe and radiator element together are less than one-third the mass of conventional heat pipes of the same heat rejection surface area. To prevent the molten potassium working fluid from eroding the C C heat pipe wall, the shell is lined with a thin-walled, metallic tube liner (Nb-1 wt.% Zr), which is an integral part of a hermetic metal subassembly which is furnace-brazed to the inner surface of the C-C tube. The hermetic metal liner subassembly includes end caps and fill tubes fabricated from the same Nb-1Zr alloy. A combination of laser and electron beam methods is used to weld the end caps and fill tubes. A tungsten/inert gas weld seals the fill tubes after cleaning and charging the heat pipes with potassium. The external section of this liner, which was formed by a "Uniscan" rolling process, transitions to a larger wall thickness. This section, which protrudes beyond the C-C shell, constitutes the "evaporator" part of the heat pipe, while the section inside the shell constitutes the condenser of the heat pipe (see figure).

  20. Fish Pectoral Fin Hydrodynamics; Part II: Numerical Simulations and Analysis

    Science.gov (United States)

    Dong, H.; Madden, P. G.

    2005-11-01

    High-fidelity numerical simulations are being used to examine the key hydrodynamic features and thrust performance of the pectoral fin of a bluegill sunfish which is moving at a constant forward velocity. The numerical modeling approach employs a parallelized immersed boundary solver which can perform direct (DNS) or large-eddy simulation (LES) of flow past highly deformable bodies such as fish pectoral fins. The three-dimensional, time-dependent fin kinematics is obtained via a stereo-videographic technique and experiments also provide PIV data which is used to validate the numerical simulations. The primary objectives of the CFD effort are to quantify the thrust performance of the bluegill sunfish pectoral fin as well as to establish the mechanisms responsible for thrust production. Simulations show that the pectoral fin produces a relatively large amount of thrust at all phases in the fin motion while limiting the magnitude of the transverse forces. The motion of the fin produces a distinct system of connected vortices which are examined in detail in order to gain insight into the thrust producing mechanisms.

  1. Design, Implementation and Control of a Fish Robot with Undulating Fins

    OpenAIRE

    Mohsen Siahmansouri; Ahmad Ghanbari; Mir Masoud Seyyed Fakhrabadi

    2011-01-01

    Biomimetic robots can potentially perform better than conventional robots in underwater vehicle designing. This paper describes the design of the propulsion system and depth control of a robotic fish. In this study, inspired by knife fish, we have designed and implemented an undulating fin to produce propulsive force. This undulating fin is a segmental anal fin that produces sinusoidal wave to propel the robot. The relationship between the individual fin segment and phase angles with the over...

  2. Metal/ceramic niobium composite fin heat pipes for a low mass radiator

    International Nuclear Information System (INIS)

    Niobium/alumina composite materials show promise for providing low mass fin heat pipes for space heat rejection systems. These heat pipes would be incorporated into a large radiator for waste heat rejection from a space nuclear power source. Current fabrication technology limits the heat pipes to straight lengths, although different cross-sections can be fabricated. A radiator analytical model was developed and used to examine the effects of fin pipe cross-section and fin material on radiator mass. Carbon-Carbon, Compglas, and beryllia fins were examined. The overall radiator mass was only slightly affected by the choice of material, however, the carbon-carbon design required fewer fin heat pipes. Radiators with carbon-glass composite (Compglas) fins had a slightly higher mass, but may still be attractive based on the other properties of Compglas, including resistance to atomic oxygen, and the ability to be fabricated into thin sheets. Square Nb/Alumina tubes have already been fabricated, while rectangular niobium composite tube is under development. These tubes will be bonded to carbon-carbon or Compglas fins, and fabricated into sodium heat pipes

  3. Evaluating the Fin-ray Trajectory Tracking of Bio-inspired Robotic Undulating Fins via an Experimental-numerical Approach

    Directory of Open Access Journals (Sweden)

    Xiaojia Xiang

    2014-07-01

    Full Text Available In the past decade, biomimetic undulating fin propulsion has been one of the main topics considered by scientists and researchers in the field of robotic fish. This technology is inspired by the biological wave-like propulsion of ribbon-finned fish. The swimming modes have aquatic application potentials with greater manoeuvrability, less detectable noise or wake and better efficiency at low speeds. The present work concentrates on the evaluation of fin-ray trajectory tracking of biorobotic undulating fins at the levels of kinematics and hydrodynamics by using an experimental-numerical approach. Firstly, fin-ray tracking inconsistence between the desired and actual undulating trajectories is embodied with experimental data of the fin prototype. Next, the dynamics' nonlinearity is numerically and analytically unveiled by using the computational fluid dynamics (CFD method, from the viewpoint of vortex shedding and the hydro-effect. The evaluation of fin-ray tracking performance creates a good basis for control design to improve the fin-ray undulation of prototypes.

  4. Three-phase synchronous motor with HTSL rotor winding and HTSL bearings. Project: HTS motor cooling system with high-performance pulsed tube cooler. Final report

    International Nuclear Information System (INIS)

    A pulsed tube cooler was to be developed for the temperature range of 25-30 K and a high cooling capacity of 40-50 W, and an optimized cooler for the HTS motor was to be constructing. Problems to be solved related to the thermal coupling of the cooler to the rotating HTS rotor (coupled or stationary cooler?) and the performance stability of the pulsed tube boiler. (orig.)

  5. The dorsal fin engine of the seahorse (Hippocampus sp.).

    Science.gov (United States)

    Consi, T R; Seifert, P A; Triantafyllou, M S; Edelman, E R

    2001-04-01

    The muscles, fin ray joints, and supporting structures underlying the dorsal fin are described for two seahorse species: Hippocampus zosterae and Hippocampus erectus. A fan-shaped array of cartilaginous bones, the pterigiophores, form the internal supporting structure of the dorsal fin. Each pterigiophore is composed of a proximal radial that extends from a vertebra to the dorsal side of the animal, where it fuses to a middle radial. The middle radials fuse with each other to form a dorsal ridge upon which sit the spheroidal distal radials. Each distal radial articulates with a fin ray on its dorsal side and is attached to the dorsal ridge on its ventral side by a material that has been histologically identified as elastic cartilage. Together these connections form a two-axis joint that permits elevation, depression, and inclination of the ray. Each fin ray is actuated by two bilateral pairs of muscles, an anterior pair of inclinators, and a posterior pair of depressors. The anteriormost fin ray is actuated by three bilateral pair of muscles, the inclinators, the depressors, and a pair of elevator muscles that are positioned anterior to the inclinators. Preliminary examinations of the ray joints of the pectoral and anal fins of adult H. zostera and the pectoral fins of newborn H. erectus revealed structures similar to that seen in the dorsal fins. To further explore the structure and function of the dorsal fin gross dissections and simple functional tests were performed on H. erectus and H. barbouri and behavioral observations were made of all three species plus Hippocampus kuda. PMID:11268060

  6. Photon counting CT at elevated X-ray tube currents: contrast stability, image noise and multi-energy performance

    Science.gov (United States)

    Kappler, S.; Henning, A.; Kreisler, B.; Schoeck, F.; Stierstorfer, K.; Flohr, T.

    2014-03-01

    The energy-selectivity of photon counting detectors provides contrast enhancement and enables new material-identification techniques for clinical Computed Tomography (CT). Patient dose considerations and the resulting requirement of efficient X-ray detection suggest the use of CdTe or CdZnTe as detector material. The finite signal pulse duration of several nanoseconds present in those detectors requires strong reduction of the pixel size to achieve feasible count rates in the high-flux regime of modern CT scanners. Residual pulse pile-up effects in scans with high X-ray fluxes still can limit two key properties of the counting detector, namely count-rate linearity and spectral linearity. We have used our research prototype scanner with CdTe-based counting detector and 225?m small pixels to investigate these effects in CT imaging scenarios at elevated X-ray tube currents. We present measurements of CT images and provide a detailed analysis of contrast stability, image noise and multi-energy performance achieved with different phantom sizes at various X-ray tube settings.

  7. Development of high performance moving-coil linear compressors for space Stirling-type pulse tube cryocoolers

    Science.gov (United States)

    Dang, Haizheng

    2015-06-01

    This paper presents a review of the recent development of moving-coil linear compressors for space Stirling-type pulse tube cryocoolers in National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences. The design, manufacture and assembly methods are described with special emphases laid on linear motor, clearance seal, flexure springs, dual-opposed configuration and flexible design. Several key components are focused on and studied in a detailed way in terms of material selection, geometry design, configuration optimization, manufacture approaches and optimal assembly to achieve high efficiency, easy producibility, high reliability and long life. Experiences from the forerunners and the state-of-the-art approaches are reviewed and used for useful references, while our own successful experiences are emphasized and discussed in more detail together with some lessons learned. A series of compressors for space applications have been worked out with high confidence of reliability and long life expectation, which achieve input capacities of 0-500 W with motor efficiencies of 74.2-83.6%. Single-stage pulse tube cryocoolers driven by these compressors have already covered the temperature range of 25-200 K with cooling capacities varying from milliwatt levels to over 30 W. The commonly-used compressor types and purposes, performance characteristics and their applications in typical space cryocooler projects are also presented.

  8. Experimental Performance of a Solar Thermoelectric Cogenerator Comprising Thermoelectric Modules and Parabolic Trough Concentrator without Evacuated Tube

    Science.gov (United States)

    Miao, L.; Kang, Y. P.; Li, C.; Tanemura, S.; Wan, C. L.; Iwamoto, Y.; Shen, Y.; Lin, H.

    2015-06-01

    A prototype practical solar-thermoelectric cogenerator composed of (1) a primary component of a pile of solar-selective absorber (SSA) slab, thermoelectric (TE) modules, and a depressed water flow tube (multichannel cooling heat sink, MCS), and (2) a parabolic trough concentrator with aperture area of 2m × 2m and east-west focal axis was constructed. Its cogeneration performance under the best climatic and solar insolation conditions in Guangzhou, China was tested. For simplicity, the evacuated glass tube to cover the primary component was eliminated from the system. Six Bi2Te3 TE modules were arranged in series, directly bonded to the rear surface of the solar absorber slab. The hot-side temperature of the TE module reached up to 152°C. The experimentally obtained instantaneous results for the solar to electrical conversion efficiency, heat exchange coefficient of the MCS, and overall system efficiency under the best environmental and solar insolation conditions were about 1.14%, 56.1%, and 49.5%, respectively. To justify these values, an equivalent thermal network diagram based on a single-temperature-node heat transfer model representing the respective system components was used to analyze the thermal transfer and losses of the system. Finally, electrical power of 18° W was generated, with 2 L/min of hot water at 37°C being produced and stored in the insulated container.

  9. Performances of Dose Measurement of Commercial Electronic Dosimeters using Geiger Muller Tube and PIN Diode

    International Nuclear Information System (INIS)

    There are two categories in personal dosimeters, one is passive type dosimeter such as TLD (thermoluminescence dosimeter) and the other is active type dosimeter such as electronic dosimeter can show radiation dose immediately while TLD needs long time to readout its data by heating process. For improving the reliability of measuring dose for any energy of radiations, electronic dosimeter uses energy filter by metal packaging its detector using aluminum or copper, but measured dose of electronic dosimeter with energy filter cannot be completely compensated in wide radiation energy region. So, in this paper, we confirmed the accuracy of dose measurement of two types of commercial EPDs using Geiger Muller tube and PIN diode with CsI(Tl) scintillator in three different energy of radiation field. The experiment results for Cs-137 was almost similar with calculation value in the results of both electronic dosimeters, but, the other experiment values with Na-22 and Co-60 had higher error comparing with Cs-137. These results were caused by optimization of their energy filters. The optimization was depending on its thickness of energy filter. So, the electronic dosimeters have to optimizing the energy filter for increasing the accuracy of dose measurement or the electronic dosimeter using PIN diode with CsI(Tl) scintillator uses the multi-channel discriminator for using its energy information

  10. A performance study of the micro-channel plate photomultiplier tube (MCP-PMT)

    Science.gov (United States)

    Dixon, Kahlil; Chiu, Mickey

    2013-10-01

    PHENIX, the Pioneering High Energy Nuclear Interaction Experiment at Brookhaven National Laboratory (BNL), is developing particle detectors of exceptional time resolution. These world-class detectors will serve as upgrade options for future modifications to the Phenix detector, a part of BNL's Relativistic Heavy-Ion Collider (RHIC). This summer, we worked to optimize the timing resolution of the prototypes to ten picoseconds. The completed detectors will supply researchers with valuable data in the runs following installation, data that is currently in kinematically inaccessible regions. We setup the detectors in a cosmic ray test. The prototype detector I worked with is a Photonics 85012xp micro-channel-plate photomultiplier tube (MCP-PMT). Our testing setup makes use of two scintillator paddles, to trigger on the muons, and two MCP-PMT prototypes, to determine the time resolution. Currently, we are in the process of carefully analyzing the data acquired during experimentation. It will take just a little more time to study the correlations in detections between the top and bottom detectors; however, we are confident that this will be excellent option for serious consideration for installation in the Phenix detector. This project was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Visiting Faculty Program (VFP).

  11. Performances of Dose Measurement of Commercial Electronic Dosimeters using Geiger Muller Tube and PIN Diode

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Hyunjun; Kim, Chankyu; Kim, Yewon; Kim, Giyoon; Cho, Gyuseong [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2014-05-15

    There are two categories in personal dosimeters, one is passive type dosimeter such as TLD (thermoluminescence dosimeter) and the other is active type dosimeter such as electronic dosimeter can show radiation dose immediately while TLD needs long time to readout its data by heating process. For improving the reliability of measuring dose for any energy of radiations, electronic dosimeter uses energy filter by metal packaging its detector using aluminum or copper, but measured dose of electronic dosimeter with energy filter cannot be completely compensated in wide radiation energy region. So, in this paper, we confirmed the accuracy of dose measurement of two types of commercial EPDs using Geiger Muller tube and PIN diode with CsI(Tl) scintillator in three different energy of radiation field. The experiment results for Cs-137 was almost similar with calculation value in the results of both electronic dosimeters, but, the other experiment values with Na-22 and Co-60 had higher error comparing with Cs-137. These results were caused by optimization of their energy filters. The optimization was depending on its thickness of energy filter. So, the electronic dosimeters have to optimizing the energy filter for increasing the accuracy of dose measurement or the electronic dosimeter using PIN diode with CsI(Tl) scintillator uses the multi-channel discriminator for using its energy information.

  12. CACHE: an extended BASIC program which computes the performance of shell and tube heat exchangers

    International Nuclear Information System (INIS)

    An extended BASIC program, CACHE, has been written to calculate steady state heat exchange rates in the core auxiliary heat exchangers, (CAHE), designed to remove afterheat from High-Temperature Gas-Cooled Reactors (HTGR). Computationally, these are unbaffled counterflow shell and tube heat exchangers. The computational method is straightforward. The exchanger is subdivided into a user-selected number of lengthwise segments; heat exchange in each segment is calculated in sequence and summed. The program takes the temperature dependencies of all thermal conductivities, viscosities and heat capacities into account providing these are expressed algebraically. CACHE is easily adapted to compute steady state heat exchange rates in any unbaffled counterflow exchanger. As now used, CACHE calculates heat removal by liquid weight from high-temperature helium and helium mixed with nitrogen, oxygen and carbon monoxide. A second program, FULTN, is described. FULTN computes the geometrical parameters required as input to CACHE. As reported herein, FULTN computes the internal dimensions of the Fulton Station CAHE. The two programs are chained to operate as one. Complete user information is supplied. The basic equations, variable lists, annotated program lists, and sample outputs with explanatory notes are included

  13. Hydraulic performance evaluation of pressure compensating (pc) emitters and micro-tubing for drip irrigation system

    International Nuclear Information System (INIS)

    Drip irrigation system is necessary for those areas, where the water scarcity issues are present. The present study was conducted at the field station of Climate Change, Alternate Energy and Water Resources Institute (CAEWRI), National Agricultural Research Center (NARC), Islamabad, during 2013, regarding drip irrigation system. Drip irrigation system depends on uniform emitter application flow. All the emitters were tested and replicated thrice at pressure head (34 to 207Kpa) with an increment of 34 Kpa. The minimum and maximum discharges were 1.32 - 3.52, 3.36 - 5.42, and 43.22 - 100.99 Lph, with an average of 2.42, 4.63 and 73.66 Lph, for Bow Smith, RIS and Micro-tubing, respectively. It indicates that more than 90% of emission uniformity (EU) and uniformity coefficient (CU) for all Emitters, which shows excellent water application with least standard deviation, ranging 0.12 to 2.37, throughout the operating pressure heads in all emitters. An average coefficient of variation (CV) of all emitters were behaving less than 0.07, indicating an excellent class at all operating pressure heads between 34 to 207 Kpa. Moreover, the relationship of discharge and pressure of emitters indicates that discharge increased with the increase of pressure head. The Q-H curve plays key role in the selection of emitters. (author)

  14. Hydrodynamic analysis of a mechanical pectoral fin in viscous flows

    Science.gov (United States)

    Wang, Zhaoli; Su, Yumin; Yang, Liang; Li, Yanli

    2008-11-01

    A two-DoF (degree of freedom) motion model was established for a mechanical pectoral fin. The secondary development of FLUENT (CFD code) software, which is based on the Reynolds-Averaged Navier-Stokes equations (RANS) was adopted. The methods of dynamic mesh and post-processing system of FLUNET were also fully used. The hydrodynamic performances of mechanical pectoral fin in viscous flows were calculated and the calculating results were compared with the latest experimental results. The influences of kinetic parameters on the pectoral fin hydrodynamics were analyzed, which was a basis for the later physical experiments.

  15. Evaluating performance from spiral polyethylene tubes as solar collectors for heating swimming pools

    Energy Technology Data Exchange (ETDEWEB)

    Stefanelli, Anderson Thiago Pontes; Marchi Neto, Ismael de; Scalon, Vicente Luiz; Padilha, Alcides [UNESP, Universidade Estadual Paulista Julio de Mesquita Filho, Bauru, SP (Brazil). Dept. de Engenharia Mecanica], e-mails: scalon@feb.unesp.br, padilha@feb.unesp.br

    2010-07-01

    The solar energy is very common in the daily of citizens from different regions in world. Environmental questions and the consequent Development of renewable energy techniques were a decisive factor for expanding this market. Currently, the solar energy is present in many different devices: as direct conversion through photovoltaic panels as in solar domestic for hot water systems(SDHWS). Another common use is in the heating system for swimming pools, that could be utilized for therapeutic or comfort reasons. The main aspect that increments this use is the economy for operation of these systems. On the other hand, these systems need a high initial investment. Reducing this cost without reduction in collector efficiency using new materials and / or alternative projects is important target for new researches. Thus, this paper aims to analyze the efficiency of one of these alternative models for heating swimming pools. The conceptual device evaluated is a low cost model. It could be made from polyethylene tubes forming spiral heat exchangers. Analysis of the system is based on a dynamic model using differential equations system including solar collector and swimming pool. Experimental radiation and other environmental conditions in the region of Bauru-SP are used for analyse the dynamic behavior of the system. The simulations are based on analysis of three main parameters: number of collectors, the pump drive time and wall thickness of the collector of polyethylene. Based on these numerical tests one can conclude that this new model of solar collector for swimming pool has a better cost benefit ratio when superficial area is equal to 80% of pool area, pump operation is alternating with four minutes turned on and 28 turned off and the polyethylene wall thickness is 1.5 mm (author)

  16. Synchronized swimming: coordination of pelvic and pectoral fins during augmented punting by the freshwater stingray Potamotrygon orbignyi.

    Science.gov (United States)

    Macesic, Laura J; Mulvaney, Dana; Blevins, Erin L

    2013-06-01

    Benthic animals live at the juncture of fluid and solid environments, an interface that shapes many aspects of their behavior, including their means of locomotion. Aquatic walking and similar substrate-dependent forms of underwater propulsion have evolved multiple times in benthic invertebrate and vertebrate taxa, including batoid elasmobranchs. Skates (Rajidae) use the pelvic fins to punt across the substrate, keeping the pectoral fin disc still. Other batoids combine pelvic fin motions with pectoral fin undulation in augmented punting, but the coordination of these two modes has not been described. In this study of an augmented punter, the freshwater stingray Potamotrygon orbignyi, we demonstrate the synchrony of pelvic and pectoral fin cycles. The punt begins as the pelvic fins, held in an anterior position, are planted into the substrate and used to push the body forward. Meanwhile, a wave of pectoral fin undulation begins, increasing to maximum height just before the cycle's halfway point, when the pelvic fins reach their furthest posterior extension. The pectoral fin wave subsides as the pelvic fins return to their starting position for subsequent punts. Despite definitive links between pectoral and pelvic fin activity, we find no significant relationship between pectoral fin kinematics (frequency, wave height, and wave speed) and punt performance. However, slip calculations indicate that pectoral undulation can produce thrust and augment punting. Pelvic fin kinematics (frequency and duty factor) have significant effects, suggesting that while both sets of fins contribute to thrust generation, the pelvic fins likely determine punt performance. PMID:23477972

  17. Studies of single-photoelectron response and of performance in magnetic field of a H8500C-03 photomultiplier tube

    International Nuclear Information System (INIS)

    We studied the single-photoelectron detection capabilities of a multianode photomultiplier tube H8500C-03 and its performance in high magnetic field. Our results show that the device can readily resolve signals at the single photoelectron level making it suitable for photon detection in both threshold and ring imaging Cherenkov detectors. We also found that a large longitudinal magnetic field, up to 300 Gauss, induces a change in the relative output of at most 55% for an edge pixel, and of at most 15% for a central pixel. The H8500C-03 signal loss in transverse magnetic fields it is significantly more pronounced than for the longitudinal case. Our studies of single photoelectron reduction in magnetic fields point to the field induced misfocusing of the photoelectron extracted from the photocathode as primary cause of signal loss. With appropriate shielding this PMT could function in high magnetic field environments

  18. Indoor test for thermal performance of the Sunmaster evacuated tube (liquid) solar collector

    Science.gov (United States)

    1979-01-01

    The test procedures used to obtain the thermal performance data for a solar collector under simulated conditions are presented. Tests included a stagnation test, a time constant test, a thermal efficiency test, an incident angle modifier test, and a hot fill test. All tests were performed at ambient conditions and the transient effect and the incident angle effect on the collector were determined. The solar collector is a water working fluid type.

  19. Method for laser welding a fin and a tube

    Science.gov (United States)

    Fuerschbach, Phillip W. (Tijeras, NM); Mahoney, A. Roderick (Albuquerque, NM); Milewski, John O (Santa Fe, NM)

    2001-01-01

    A method of laser welding a planar metal surface to a cylindrical metal surface is provided, first placing a planar metal surface into approximate contact with a cylindrical metal surface to form a juncture area to be welded, the planar metal surface and cylindrical metal surface thereby forming an acute angle of contact. A laser beam, produced, for example, by a Nd:YAG pulsed laser, is focused through the acute angle of contact at the juncture area to be welded, with the laser beam heating the juncture area to a welding temperature to cause welding to occur between the planar metal surface and the cylindrical metal surface. Both the planar metal surface and cylindrical metal surface are made from a reflective metal, including copper, copper alloys, stainless steel alloys, aluminum, and aluminum alloys.

  20. PERFORMANCE OF EVACUATED TUBE SOLAR COLLECTOR USING WATER-BASED TITANIUM OXIDE NANOFLUID

    Directory of Open Access Journals (Sweden)

    M. Mahendran

    2012-12-01

    Full Text Available Experiments are undertaken to determine the efficiency of an evacuated tube solar collector using water-based Titanium Oxide (TiO2 nanofluid at the Pekan Campus (3?32’ N, 103?25’ E, Faculty of Mechanical Engineering, University Malaysia Pahang, for the conversion of solar thermal energy. Malaysia lies in the equatorial zone with an average daily solar insolation of more than 900 W/m², which can reach a maximum of 1200 W/m² for most of the year. Traditionally water is pumped through the collector at an optimum flow rate, for the extraction of solar thermal energy. If the outlet temperature of the water is high, further circulation of the water through the collector is useless. This is due to the low thermal conductivity of water of 0.6 W/m.K compared to metals which is many orders higher. Hence it is necessary to reduce the surface temperature either by pumping water at a higher flow rate or by enhancing the fluid’s properties by the dispersion of nanoparticles. Pumping water at higher flow rates is not advantageous as the overall efficiency of the system is lowered. Liquids in which nanosized particles of metal or their oxides are dispersed in a base liquid such as water are known as 'Nanofluids'. This results in higher values of thermal conductivity compared to the base liquid. The thermal conductivity increases with the concentration and temperature of the nanofluid. The increase in thermal conductivity with temperature is advantageous for application in collectors as the solar insolation varies throughout the day, with a minimum in the morning reaching a maximum at 2.00p.m and reducing thereafter. The efficiency of the collector estimated using a TiO2 nanofluid of 0.3% concentration is about 0.73, compared to water which is about 0.58. The efficiency is enhanced by 16.7% maximum with 30–50nm sized TiO2 nanoparticles dispersed in the water, compared to the system working solely with water. The flow rate is fixed at 2.7 liters per minute for both liquids.

  1. Labriform swimming of a ray-strengthened pectoral fin

    Science.gov (United States)

    Shoele, Kourosh; Zhu, Qiang

    2009-11-01

    Labriform swimming is a common locomotion mode used by fish in low speed swimming, in which thrust generation is achieved through a combination of flapping and rowing motions of pectoral fins. Pectoral fins of bony fishes usually consist of a soft collagen membrane strengthened by embedded flexible rays. Morphologically, each ray is connected to a group of muscles so that the fish can control the rotational motion of each ray individually, enabling multi-degree of freedom control over the fin motion and deformation. We have developed a fluid-structure interaction model to simulate the kinematics and dynamic performance of a structurally idealized fin. This method includes a boundary-element model of the fluid motion and a fully-nonlinear Euler-Bernoulli beam model of the embedded rays. Using this model we studied thrust generation and propulsion efficiency of the fin at different combinations of parameters. Effects of kinematic as well as structural properties are examined. It has been illustrated that the fish's capacity to control the motion of each individual ray, as well as the anisotropic deformability of the fin determined by distribution of the rays, are essential to high propulsion performance. Specifically, it is found that a reinforced ray at the leading edge leads to performance enhancement.

  2. Eddy-Current Testing of Finned Fuel Cladding

    International Nuclear Information System (INIS)

    Eddy-current methods of testing reactor-fuel components are well established. The literature, however, mainly describes tests which are applied to simple geometries such as cylindrical rods or tubes. Recent AECL fuel designs have called for cladding with heat transfer or locating fins along the length of the fuel. This paper describes the application of eddy-current techniques to three such designs. The function and geometry of the fins must be considered in the selection of the optimum test parameters and the most suitable test coil geometry. Thus, the presence of fins may limit or restrict the test but they will not prevent a successful test. Where the fin geometry is complex eddy currents may well be the most suitable of the non-destructive methods which can be used for flaw detection. The thickness of aluminium cladding over a uranium core is measured with a small probe coil placed between the fins and shielded from them. Two flaw detection tests are described, one on sintered aluminium product (SAP) tubing using an internal bobbin coil and the other on an aluminium-clad uranium-aluminium alloy rod with an external encircling coil. The instrumentation described is relatively simple. A small portable instrument was designed for the cladding thickness measurement. For flaw detection a standard oscilloscope with a plug-in carrier-amplifier module provides a means of sensing and displaying the test coil impedance variations. This equipment ,although it does not permit sophisticated methods of eliminating unwanted noise is adequate for a variety of testing applications and has been specified for routine fuel testing on a production basis. (author)

  3. Experimental investigation of the higher coefficient of thermal performance for water-in-glass evacuated tube solar water heaters in China

    International Nuclear Information System (INIS)

    Highlights: • The energy grades system for solar water heater (SWH) in China was introduced. • Heat loss and capacity of heat collection mainly affected SWH thermal performance. • Optimum ratio of tank volume to collector area for solar water heater is 57 to 72 L/m2. • The recommendation polyurethane insulation layer should be around 50 mm thick. • SWH with shorter tube has a better thermal performance. - Abstract: Solar water heaters (SWHs), now widely used in China, represent an environmentally friendly way to heat water. We tested the performance of more than 1000 water-in-glass evacuated tube SWHs according to Chinese standards and found that the heat loss from the storage tank and capacity of the solar collector affected their thermal performance. The optimum parameters to maximize the performance of water-in-glass evacuated tube SWHs included a ratio of tank volume to collector area of 57–72 L/m2, which should give a system efficiency of 0.49–0.57, meaning that the temperature of water in the tank will exceed 45 °C after one day of heat collection. In addition, the polyurethane insulation layer should be around 50 mm thick with a free foaming density of about 35 kg/m3, and the evacuated tube should be short. The tilt angle did not affect the performance of the SWHs. These results should aid in the design of highly efficient SWHs

  4. Highly sensitive copper fiber-in-tube solid-phase microextraction for online selective analysis of polycyclic aromatic hydrocarbons coupled with high performance liquid chromatography.

    Science.gov (United States)

    Sun, Min; Feng, Juanjuan; Bu, Yanan; Luo, Chuannan

    2015-08-21

    A fiber-in-tube solid-phase microextraction (SPME) device was developed with copper wire and copper tube, which was served as both the substrate and sorbent with high physical strength and good flexibility. Its morphology and surface properties were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. It was coupled with high performance liquid chromatography (HPLC) equipment by replacing the sample loop of six-port injection valve, building the online SPME-HPLC system conveniently. Using ten polycyclic aromatic hydrocarbons (PAHs) as model analytes, extraction conditions including sampling rate, extraction time, organic content and desorption time were investigated and optimized. The copper fiber-in-tube exhibits excellent extraction efficiency toward PAHs, with enrichment factors from 268 to 2497. The established online SPME-HPLC method provides good linearity (0.05-100?gL(-1)) and low detection limits (0.001-0.01?gL(-1)) for PAHs. It has been used to determine PAHs in water samples, with recoveries in the range of 86.2-115%. Repeatability on the same extraction tube is in the range of 0.6-3.6%, and repeatability among three tubes is in the range of 5.6-20.1%. Compared with phthalates, anilines and phenols, the copper fiber-in-tube possesses good extraction selectivity for PAHs. The extraction mechanism is probably related to hydrophobic interaction and ?-electron-metal interaction. PMID:26189674

  5. Forced Convection Heat Transfer Experiments of the Finned Plate in a Duct

    Energy Technology Data Exchange (ETDEWEB)

    Chae, Myeongseon; Moon, Jeyoung; Chung, Bumjin [Kyung Hee Univ., Yongin (Korea, Republic of)

    2014-05-15

    The studies have been focused on the optimization of fin geometries to maximize the heat transfer rate. The forced convection heat transfer rates were affected largely by the fin spacing, fin height, and tip clearance. As the fin spacing decreases and fin height increases, heat transfers from the fins to the ambient are enhanced as they are directly proportional to the surface area. For a large tip clearance, the fluid tends to escape from the inner fin region to the outer wall region resulting in the decrease of the overall heat removal capability. Thus, the parametric influences of these variables are to be investigated to develop a generalized heat transfer correlation for the geometry. This study is a preliminary experimental study for plate-fin geometries such as fin spacing, fin height and duct width. Mass transfer experiments were carried out based on the analogy concept, using a copper sulfate electroplating system. The work has the relevance with the Reactor Cavity Cooling System performance enhancement study in the VHTR. Forced convection heat transfer experiments were performed for the vertical plate-fins in a duct. Based on the analogy between heat and mass transfer systems, mass transfer rates were measured using the cupric acid copper sulfate electroplating system. The fin spacings were varied from 0.002m to 0.007m, fin heights 0.01m and 0.015m, Re{sub Dh} from 10 to 6,500, and duct widths from 0.010m to 0.02m. The test results showed that the heat transfer rates enhanced with the increase of fin height and the decrease of fin spacing as they enlarge the heat transfer area. And the heat transfer rates were impaired with the increase of the duct width as the bypass flows increased to tip clearance region.

  6. The cooling performance of SiC/water nano fluid during reflood heat transfer in a long vertical tube

    International Nuclear Information System (INIS)

    Many researchers have been trying to create new kinds of heat transfer fluids in order to enhance the heat transfer performance of the base fluids. Nano fluids as new kinds of heat transfer fluids are a new class of nano technology based heat transfer fluids engineered by dispersing nanoparticles into conventional heat transfer fluids such as water, ethylene glycol, and engine oil. Most of the studies on a heat transfer of nano fluids have been concentrated on the nucleate boiling region and the C HF phenomenon. A quenching phenomenon is important for analysis of the reflood phase associated with the emergency cooling in water cooled nuclear reactor core under a loss of coolant accident and the reflood is happened when water refills the reactor vessel and quenches the fuel rod at the time of the severe accident in nuclear power plant. The use of other fluids instead of water for the quenching experiment in the sphere and rod let specimens has been investigated by many researchers. In this work, we have observed a quenching phenomenon of a hot vertical tube during a reflood using SiC/water nano fluid as a coolant, instead of water. Experiments were conducted to investigate the effect of SiC/water nano fluid on reflood heat transfer in a long vertical tube. The cause selecting SiC nanoparticles is that applying SiC as a cladding material for a light water nuclear reactor is considering because the resistance of SiC to the high-temperature and high radiation environment is good. 0.01 volume fraction (%) SiC/water nano fluid was prepared by two step method

  7. Comparative Performance of the Photomultiplier Tube and the Silicon Avalanche Photodiode When Used as Detectors in Angular Scattering Measurements

    Science.gov (United States)

    Kroner, D. O.; Nelson, R. M.; Boryta, M. D.; Hapke, B. W.; Manatt, K.; Smythe, W. D.

    2014-12-01

    We report the results of a comparative study of two types of photometric detectors that are commonly used for, spacecraft, ground-based telescope, and laboratory observations in support of precise angular scattering investigations of the type described in a companion paper (Nelson et al., this meeting). The performance of the state of the art Hamamatsu C12703-01 Silicon Avalanche photodiode (SAD) was compared to that of the Hamamatsu R928 Photomultiplier tube (PMT). The Hamamatsu R928 evolved from a sequence of photometric detectors with a long history of use in support of laboratory and remote sensing studies, tracing backwards to include the RCA 1P21 and the RCA 931A. Two newly acquired SADs were bench tested along with a new R928 photomultiplier tube that was thermoelectrically cooled to -10 deg C. The SAD's employed electronic thermal compensation supplied by the manufacturer. The SADs and PMT measured electromagnetic radiation from solid-state lasers of wavelength 635 nm after the radiation was reflected from diffusely-scattering surfaces of varying albedos. The SADs were housed on tripods that were co-aligned with the PMT and laser. The photometric detectors were placed 4.3 meters from a reflecting disk. The disk was rotated to reduce the effect of laser speckle. All detectors in the experiment were equipped with notch filters that transmit light only of the wavelength emitted by the laser. Three SR830 DSP Lock-in Amplifiers were connected to the detectors and various setting configurations were compared in order to optimize signal to noise. Neutral Density filters (ND 0,3 and ND 0,9) were placed in the light path to determine the linearity in the response function of the detectors. We conclude that in this application SADs and PMTs produce comparable photometric precision and fidelity. SADs offer greater convenience because thermal compensation circuitry is integrated with the detector. This work was partially supported by NASA's Cassini Science Investigation program.

  8. High efficiency fluorescent tubes; Les tubes fluorescents haut rendement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-12-01

    This brochure presents all technical aspects relative to high efficiency fluorescent tubes: lighting efficiency, advantages, comfort, collection and processing of used tubes, labelling and warranties, costs and performances, regulatory texts and standards. (J.S.)

  9. Dynamics of tubes in fluid with tube-baffle interaction

    International Nuclear Information System (INIS)

    Three series of tests are performed to evaluate the effects of tube to tube-support-plate (TSP) clearance on tube dynamic characteristics and instability phenomena for tube arrays in crossflow. Test results show that, for relatively large clearances, tubes may possess TSP-inactive modes in which the tubes rattle inside some of the tube-support-plate holes, and that the natural frequencies of TSP-inactive modes are lower than those of TSP-active modes, in which the support plates provide knife-edge type support. Tube response characteristics associated with TSP-inactive modes are sensitive to tube-to-TSP clearance, TSP thickness, excitation amplitude, tube alignment, and the fluid inside the clearance. In addition, tube response is intrinsically nonlinear, with the dominance of TSP-inactive or TSP-active modes depending on the magnitudes of different system parameters. In general, such a system is difficult to model; only a full-scale test can provide all the necessary characteristics. A tube array supported by TSPs with relatively large clearances may be subjected to dynamic instability in some of the TSP-inactive modes; tube response characteristics and impact forces on TSPs for a tube row are studied in detail in this report. Tube displacements associated with the instability of a TSP-inactive mode are small; however, impacts of the tube against TSPs may result in significant damage in a relatively short time. 52 figures

  10. Stress analysis of plate-fin structures in recuperator

    International Nuclear Information System (INIS)

    A high performance compact recuperator with 95% effectiveness is required to achieve a high thermal efficiency power generation of up to 50% in High Temperature Gas Cooled Reactor (HTGR) coupled with closed cycle helium gas turbine. Though a plate-fin type heat exchanger is proposed for this recuperator, much research and development works are needed to establish this high performance goal since there exists no state-of-the-art technology in such a high pressure and high temperature one. One of the important works is to establish the structural analysis and evaluation method in this plate-fin type heat exchanger. This paper describes the results of stress analysis of the plate-fin structure under the internal pressure as the first step of this work. First, the modeling of a unit plate-fin structure for the analysis was examined and a three layers model was confirmed to be most adequate. The stress distribution within the structure was clarified by using this model. Second, the three layers model was simplified to one layer model with sufficient accuracy. By using this model, both the effects of an inclined angle of fin and a thickness of separate on the strength were examined parametrically. Under the relevant design conditions, it was revealed that the optimum inclined angle of fin locates in the neighborhood of 76 degree rather than most difficult fabrication angle 90 degree and there is possibility to adopt thinner thickness than 0.5 mm in the current design. (author)

  11. Thermal issues associated with the HVAC and lighting systems influences on the performance of the national ignition facility beam transport tubes

    International Nuclear Information System (INIS)

    This report summarizes an investigation of the thermal issues related to the National Ignition Facility. In particular, the influences of the HVAC system and lighting fixtures on the operational performance of the laser guide beam tubes are reviewed and discussed. An analytical model of the oscillating HVAC air temperatures in the NIF switchyard and target bay will cause significant amounts of beam distortion. However, these negative effects can be drastically reduced by adding thermal insulation to the outside of the beam tubes. A computational fluid dynamics model and an analytical investigation found that the light-fixture to beam-tube separation distance must be on the order of 5.7 m (18.7 ft) to maintain acceptable beam operating performance in the current NIF design. By reducing the fluorescent light fixture power by 33% this separation distance can be reduced to 3.5 m (11.5 ft). If in addition, thermal insulation with a reflective aluminum foil covering is added to the outside of the beam tubes, the separation distance can be reduced further to 1.6m (5.2 ft). A 1.27 cm (0.5 in.) rigid foam insulation sheet with aluminum foil covering will provide adequate insulation for the beam tubes in the NIF switchyards and target bay. The material cost for this amount of insulation would be roughly $30,000

  12. Method of making heat transfer tube with improved outside surface for nucleate boiling

    International Nuclear Information System (INIS)

    This patent describes a process for making a heat transfer tube with an improved outside surface for nucleate boiling comprising the steps of finning the tube to produce helical fins thereon, forming transverse grooves around the periphery of each fin, and progressively compressing the tips of the grooved fins to cause them to become flattened and of a width in an axial direction which is slightly less than their pitch, thereby defining a narrow opening between fins which is communication with a rather large cavity defined by the sides of adjacent fins in the region under the flattened fin tips. The improvement is described wherein the tips are variably compressed so that the width of the narrow openings adjacent fins is varied so as to produce a range of opening widths which is both larger and smaller than the optimum minimum pore size for nucleate boiling of a particular fluid under a particular set of operating conditions

  13. The ATLAS TRT straw proportional tubes performance at very high counting rate

    CERN Document Server

    Åkesson, T; Dolgoshein, B A; Fabjan, Christian Wolfgang; Farthouat, Philippe; Froidevaux, Daniel; Fuchs, W; Gavrilenko, I; Holder, M; Ivochkin, V G; Kondratev, O V; Konovalov, S V; Lichard, P; Malecki, P; Muraviev, S; Nadtochy, A; Nevski, P; Norton, P R; Peshekhonov, V D; Pavlenko, S; Richter, R H; Romaniouk, A; Saxon, D H; Schegelsky, V A; Shmeleva, A; Semenov, S V; Smirnov, S; Sosnovtsev, V V; Spiridenkov, E M; Stavrianakou, M; Schuh, S; White, D J

    1995-01-01

    A 864 channel prototype of an integrated straw tracker and transition radiation detector for tracking and electron identification has been tested with and without magnetic field at the CERN SPS. The rejection against hadrons and converted photons has been measured and the dependence of the rejection power on detector parameters has been investigated. Tracking and hadron rejection were also studied in a high multiplicity environment. The results are compared with Monte-Carlo simulations. Wherever possible, conclusions are drawn concerning the performance of a full-scale detector at the future Large Hadron Collider.

  14. Negative effect of smoking on the performance of the QuantiFERON TB gold in tube test

    Directory of Open Access Journals (Sweden)

    Aabye Martine G

    2012-12-01

    Full Text Available Abstract Background False negative and indeterminate Interferon Gamma Release Assay (IGRA results are a well documented problem. Cigarette smoking is known to increase the risk of tuberculosis (TB and to impair Interferon-gamma (IFN-? responses to antigenic challenge, but the impact of smoking on IGRA performance is not known. The aim of this study was to evaluate the effect of smoking on IGRA performance in TB patients in a low and high TB prevalence setting respectively. Methods Patients with confirmed TB from Denmark (DK, n?=?34; 20 smokers and Tanzania (TZ, n?=?172; 23 smokers were tested with the QuantiFERON-TB Gold In tube (QFT. Median IFN-? level in smokers and non smokers were compared and smoking was analysed as a risk factor for false negative and indeterminate QFT results. Results Smokers from both DK and TZ had lower IFN-? antigen responses (median 0.9 vs. 4.2 IU/ml, p?=?0.04 and 0.4 vs. 1.6, p? Conclusions Cigarette smoking was associated with false negative and indeterminate IGRA results in both a high and a low TB endemic setting independent of HIV status.

  15. The ATLAS TRT straw proportional tubes: performance at very high counting rate RD6 Collaboration

    International Nuclear Information System (INIS)

    Results on analog front-end electronics and straw performance studies at high counting rates are described. Prototypes of the electronics have been tested at counting rates up to 17.5 MHz. A drift-time accuracy of 180 ?m and a drift-time measurement efficiency of 53% were obtained at 17.5 MHz. The expected counting rate is between 5 and 15 MHz (depending on straw position) for the ATLAS straw tracker at LHC design luminosity, leading to an estimated drift-time accuracy at 160 ?m and hit registration efficiency of 68% for the average counting rate of 10 MHz. These results are in a good agreement with detailed MC simulations and could be improved with better front-end electronics. (orig.)

  16. QuantiFERON®-TB gold in-tube performance for diagnosing active tuberculosis in children and adults in a high burden setting

    DEFF Research Database (Denmark)

    Rose, Michala Vaaben; Kimaro, Godfather; Nissen, Thomas N; Kroidl, Inge; Hoelscher, Michael; Bygbjerg, Ib C; Mfinanga, Sayoki G; Ravn, Pernille

    2012-01-01

    To determine whether QuantiFERON®-TB Gold In-Tube (QFT) can contribute to the diagnosis of active tuberculosis (TB) in children in a high-burden setting and to assess the performance of QFT and tuberculin skin test (TST) in a prospective cohort of TB suspect children compared to adults with confirmed TB in Tanzania.

  17. Simulation study of a 3-D device integrating FinFET and UTBFET

    KAUST Repository

    Fahad, Hossain M.

    2015-01-01

    By integrating 3-D nonplanar fins and 2-D ultrathin bodies, wavy FinFETs merge two formerly competing technologies on a silicon-on-insulator platform to deliver enhanced transistor performance compared with conventional trigate FinFETs with unprecedented levels of chip-area efficiency. This makes it suitable for ultralarge-scale integration high-performance logic at and beyond the 10-nm technology node.

  18. Experimental investigation and thermodynamic performance analysis of a solar dryer using an evacuated-tube air collector

    International Nuclear Information System (INIS)

    Highlights: ? We evaluate an evacuated-tube solar air collector and use it to develop a novel dryer. ? Apple, carrot and apricot thin-layer drying experiments are conducted. ? Best overall fitting among several available thin-layer drying models is pursued. ? Thermodynamic analysis yields optimal collector area, energy utilization/exergy loss. ? The proposed dryer has a capacity for drying larger quantities of products. -- Abstract: The present work presents a thermodynamic performance analysis of a solar dryer with an evacuated-tube collector. Drying experiments for apples, carrots and apricots were conducted, after a preliminary stage of the investigation which included measurements for the determination of the collector efficiency. These results showed that the warm outlet air of the collector attains temperature levels suitable for drying of agricultural products without the need of preheating. Thus, the present collector was used as the heat source for a drying chamber in the frame of the development of a novel, convective, indirect solar dryer; given the fact that in the literature there are only a few studies about this type of collectors in conjunction with solar drying applications. Thin-layer drying models were fitted to the experimental drying curves, including the recent model of Diamante et al. which showed good correlation coefficients for all the tested products. Drying parameters such as moisture ratio and drying rates were calculated. Furthermore, an energetic/exergetic analysis of the dryer was also conducted and performance coefficients such as pick-up and exergy efficiencies, energy utilization ratio, exergy losses were determined for several configurations such as single and double-trays and several drying air velocities. On the other hand, an optimal collector surface area study was conducted, based on laws for minimum entropy generation. Design parameters such as optimum collector area were determined based on the minimum entropy generation number. The mass flow number, along with the maximum collector and fluid exit temperatures were studied in relation to the minimum entropy generation. The energy/exergy analysis proposed, provides a useful tool for the evaluation of this type of collectors regarding their effectiveness as part of a solar drying system. Moreover, the results of the present study showed that the proposed solar dryer has a capacity for drying larger quantities of the products than those considered (in the frame of the experimental study) given the high efficiency of the collector. In general, the proposed system provides an interesting option for the penetration of this type of collectors in large-scale applications in the agricultural and industrial sector.

  19. Thermal analysis of baffled shell and tube type EGR cooler for different types of tubes using CFD

    Directory of Open Access Journals (Sweden)

    Ibrahim Hussain Shah

    2014-08-01

    Full Text Available Exhaust Gas Recirculation (EGR technique using EGR cooler reduces the NOx content from the tailpipe emission of Diesel engines. Commercial computational fluid dynamics (CFD code is used to solve and simulate the flow-fields and temperature distribution of fluids inside the EGR cooler. In this investigation two models (model-a and model-b of EGR coolers are developed using Pro/Engineer Wildfire 4.0 software. Model-a is a single pass baffled shell and tube heat exchanger with staggered tube arrangement of plain tubes and having conical shaped stationary heads (gas inlet/outlet chamber [2]. Model-b is having the same tube arrangement and spacing as they were in model-a, but the plain tubes were replaced with internally finned tubes to increase the internal surface area of tubes. The finned tubes are of same outer diameter and same tube material as that of plain tubes. In model-a and model-b, the inlet conditions of both the cooling water and hot gases are the same. These models are analysed with Ansys Fluent 13.0 software. The CFD results show that, by replacing the plain tubes with internally finned tubes, the rate of heat exchange between the cooling water and hot gases enhanced.

  20. Performance of multiple mini-tube heat exchangers as an internal heat exchanger of a vapor-injection cycle heat pump

    Science.gov (United States)

    Jang, Jin Yong; Jeong, Ji Hwan

    2015-05-01

    A multiple mini-tube (MMT) heat exchanger was considered as an internal heat exchanger of vapor-injection cycle heat pump. Heat transfer and pressure drop in multiple mini-tube heat exchangers were numerically and experimentally investigated. Results show that the best performance of the MMT heat exchanger can be obtained when the intermediate-pressure two-phase refrigerant is supplied to the shell-side and this refrigerant reaches a saturated vapor state at the exit of the heat exchanger.

  1. High density turbulent plasma processes from a shock tube. Final performance report

    International Nuclear Information System (INIS)

    A broad-based set of measurements has begun on high density turbulent plasma processes. This includes determinations of new plasma physics and the initiation of work on new diagnostics for collisional plasmas as follows: (1) A transient increase is observed in both the spectral energy decay rate and the degree of chaotic complexity at the interface of a shock wave and a turbulent ionized gas. Even though the gas is apparently brought to rest by the shock wave, no evidence is found either of prompt relaminarization or of any systematic influence of end-wall material thermal conductivities on the turbulence parameters. (2) Point fluorescence emissions and averaged spectral line evolutions in turbulent plasmas produced in both the primary and the reflected shock wave flows exhibit ergodicity in the standard turbulence parameters. The data show first evidence of a reverse energy cascade in the collisional turbulent plasma. This suggests that the fully turbulent environment can be described using a stationary state formulation. In these same data, the author finds compelling evidence for a turbulent Stark effect on neutral emission lines in these data which is associated with evidence of large coherent structures and dominant modes in the Fourier analyses of the fluctuations in the optical spectra. (3) A neutral beam generator has been assembled by coupling a Colutron Ion Gun to a charge exchange chamber. Beam-target collisions where the target species is neutral and the beam is either singly charged or neutral have been performed using argon as the working gas. Spectral analysis of the emission shows specific radiative transitions characteristic of both Ar I and Ar II, indicating that some ionization of the target gas results. Gas and plasma parameters such as density, pressure, temperature and flow velocity and their fluctuations can now be followed in real time by spectroscopic analysis of carefully chosen radiative emissions

  2. Numerical Study of CNT Micro Fin Array for Cooling Application

    Directory of Open Access Journals (Sweden)

    Sajjad Nabizadeh

    2013-12-01

    Full Text Available Heat removing from a microelectronic chip packaging has grand effect on performance and durability of the chip. Today’s microchips with high power densities would require efficient methods of cooling. Recently, vertical alignment CNTs, due to their superior thermal, electrical and mechanical properties, was suggested as an effective micro cooler on the level of modern electronics demands. In this paper, the cooling performance of the CNT fin structures is studied numerically. Flow of air was considered as the working fluid flow. CFD simulations have been carried out for a series of CNT micro-fin cooling architectures based on one and two dimensional fin array models. The modeling results indicate that fluid speed is the key factor in heat transfer capacity of the device. Also, the results of 2D carbon nanotube fin array model show more precise and greater thermal performance than that of 1D model. Finally, the examination of pressure drop between inlet and outlet of the cooling device is presented as an important factor which could limit the fluid speed and fin height effect on heat sink performance also investigated.

  3. Numerical Study of CNT Micro Fin Array for Cooling Application

    Directory of Open Access Journals (Sweden)

    Sajjad Nabizadeh

    2013-12-01

    Full Text Available Heat removing from a microelectronic chip packaging has grand effect on performance and durability of the chip. Today’s microchips with high power densities would require efficient methods of cooling. Recently, vertical alignment CNTs, due to their superior thermal, electrical and mechanical properties, was suggested as an effective micro cooler on the level of modern electronics demands. In this paper, the cooling performance of the CNT fin structures is studied numerically. Flow of air was considered as the working fluid flow. CFD simulations have been carried out for a series of CNT micro-fin cooling architectures based on one and two dimensional fin array models. The modeling results indicate that fluid speed is the key factor in heat transfer capacity of the device. Also, the results of 2D carbon nanotube fin array model show more precise and greater thermal performance than that of 1D model. Finally, the examination of pressure drop between inlet and outlet of the cooling device is presented as an important factor which could limit the fluid speed and fin height effect on heat sink performance also investigated.

  4. Efficiency and entropy generation in fined tube solar collectors systems; Eficiencia e geracao de entropia em sistemas de tubos aletados coletores de energia solar

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Marcio Bueno dos [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. de Integracao e Testes; Saboya, Sergio Mourao [Instituto Tecnologico de Aeronautica, Sao Jose dos Campos, SP (Brazil). Dept. de Energia

    1998-07-01

    This paper studies the efficiency of a fined tube solar collector used in artificial satellites and the relation of this efficiency with the entropy generation in the fin. The mathematical modeling of heat transfer in the collector leads to a non-linear integrodifferential system of equations, which is solved numerically. The solution gives the efficiency, which is presented as function of geometrical and physical characteristics of the collector. It is also shown that a minimum entropy generation in the fins, in a collector, whose characteristics are subjected to constraints, corresponds to an optimum efficiency, that is, an efficiency value advantageous to collector performance. (author)

  5. Stretching/shrinking longitudinal fins of rectangular profile and heat transfer

    International Nuclear Information System (INIS)

    Highlights: • The stretching/shrinking parameter enhances the fin temperature. • The temperature is reduced by increasing the Biot number. • Higher fin efficiencies occur for shrinking fin profiles. • A shrinking fin surface performs better fin efficiency and heat transfer rate. - Abstract: The present study deals with the heat transfer enhancement and efficiency of longitudinal rectangular fin profiles when a stretching or shrinking mechanism is mounted on the surface of the fin. Exact analytic solutions are sought from which the combined effects of some physical parameters like the convection sink temperature parameter, the Peclet number, the stretching/shrinking parameter and the convection–conduction parameter (Biot number) on the efficiency of longitudinal rectangular fins against non stretched straight rectangular fins can be comparatively analyzed. It is shown that stretching degrades the efficiency, whereas shrinking provides better fin efficiency pointing to significant advantages in terms of fin design purposes. Moreover, the presented neat formulae serve a verification tool for the researchers actively working in the field, particularly when numerical methods are employed to investigate more complex phenomena

  6. Fin propulsion on a human-powered submarine

    Science.gov (United States)

    Anderson, Iain A.; Pocock, Benjamin; Harbuz, Antoni; Algie, Cam; Vochezer, Daniel; Chao, Ryan; Lu, Benjamin

    2015-03-01

    Nearly all surface and underwater vessels are driven by screw propulsion; ideal for coupling to rotary engines and well understood after over a century of development. But most aquatic creatures use fins for swimming. Although there are sound evolutionary reasons why fish have fins and not propellers, they are nevertheless agile, fast and efficient. Although fish-like robots such as the MIT Robotuna are providing good insight into fin-based swimming there are advantages for using humans in the experimental device. Like an airplane test pilot they can write crash reports. We present preliminary observations for the human powered finned submarine: Taniwha. The sub participated in the 2nd European International Submarine races in Gosport UK where it received a trophy for "Best Non-Propeller Performance". Two sets of Hobie Mirage fin drives fixed to the upper and lower rear surfaces of the sub are pedaled by the pilot. The pilot also has two levers at the front, one to pitch a pair of dive planes and one for yawing a large rudder. Good speed, we estimate to be greater than 6 m/s is possible with these fins although we haven't explored their full potential. Straying too near the surface or bottom can lead to an instability, synonymous to a stall, such that control is lost. The mechanism for this will be discussed and solutions offered. Fish are 400 million years in front of us but one day we'll catch them.

  7. Comparative Experimental Analysis of the Thermal Performance of Evacuated Tube Solar Water Heater Systems With and Without a Mini-Compound Parabolic Concentrating (CPC Reflector(C < 1

    Directory of Open Access Journals (Sweden)

    Yuehong Su

    2012-04-01

    Full Text Available Evacuated tube solar water heater systems are widely used in China due to their high thermal efficiency, simple construction requirements, and low manufacturing costs. CPC evacuated tube solar water heaters with a geometrical concentration ratio C of less than one are rare. A comparison of the experimental rig of evacuated tube solar water heater systems with and without a mini-CPC reflector was set up, with a series of experiments done in Hefei (31°53'N, 117°15'E, China. The first and second laws of thermodynamics were used to analyze and contrast their thermal performance. The water in the tank was heated from 26.9 to 55, 65, 75, 85, and 95 °C. Two types of solar water heater systems were used, and the data gathered for two days were compared. The results show that when attaining low temperature water, the evacuated tube solar water heater system without a mini-CPC reflector has higher thermal and exergy efficiencies than the system with a mini-CPC reflector, including the average and immediate values. On the other hand, when attaining high temperature water, the system with a mini-CPC reflector has higher thermal and exergy efficiencies than the other one. The comparison presents the advantages of evacuated tube solar water heater systems with and without a mini-CPC reflector, which can be offered as a reference when choosing which solar water system to use for actual applications.

  8. Feeding Tubes

    Science.gov (United States)

    ... rarely do EGID patients require total parenteral feeding (TPN). Special care and training are required to maintain the central line and administer the TPN. Tubes Used for Enteral Feeds NG (Nasogastric Tube) ...

  9. Performance Analysis of a Shell Tube Condenser for a Model Organic Rankine Cycle for Use in Geothermal Power Plant

    Directory of Open Access Journals (Sweden)

    Haile Araya Nigusse

    2014-08-01

    Full Text Available The global energy demand increases with the economic growth and population rise. Most electrical power is currently generated by conventional methods from fossil fuels. Despite the high energy demand, the conventional energy resources such as fossil fuels have been declining. In addition to this harmful combustion byproducts are resulting global warming. However, the increase of environmental concerns and energy crisis can be minimized by sustainable utilization of the low to medium temperature heat resources. The Organic Rankine Cycle power plant is a very effective option for utilization of low grade heat sources for power generation. Heat exchangers are the main components of the Organic Rankine Cycle power plant which receives heat energy from the heat source to evaporate and condense the low boiling temperature organic working fluid which in turn drives the turbine to generate power. This paper presents a simplified approach to the design, fabrication and performance assessment of a shell tube heat exchanger designed for condenser in a model Organic Rankine Cycle geothermal power plant. The design involved sizing of heat exchanger (condenser using the LMTD method based on an expected heat transfer rate. The heat exchanger of the model power plant was tested in which hot water simulated geothermal brine. The results of the experiment indicated that the heat exchanger is thermally suitable for the condenser of the model power plant.

  10. Modeling of heating and cooling performance of counter flow type vortex tube by using artificial neural network

    Energy Technology Data Exchange (ETDEWEB)

    Kocabas, Fikret [Bartin University, Faculty of Engineering, Civil Engineering Department, Bartin (Turkey); Korkmaz, Murat [Hacettepe University, Vocational High School, Department of Machinery, Polatli, Ankara (Turkey); Sorgucu, Ugur [Bartin University, Faculty of Engineering, Electrical and Electronics Engineering Department, Bartin (Turkey); Donmez, Senayi [Karatekin University Technical and Business College, Civil Engineering Department, Cankiri (Turkey)

    2010-08-15

    In this study, the effect of the nozzle number and the inlet pressures, which vary from 150 to 700 kPa with 50 kPa increments, on the heating and cooling performance of the counter flow type vortex tube has been modeled with an artificial neural network (ANN) and multi-linear regression (MLR) models by using the experimentally obtained data. In the developed system output parameter temperature gradiant between the cold and hot outlets ({delta}T) has been determined using inlet parameters such as the inlet pressure (P{sub inlet}), nozzle number (N), cold mass fraction ({mu}{sub c}) and inlet mass flow rate (m{sub inlet}). The back-propagation learning algorithm with variant which is Levenberg-Marquardt (LM) and Sigmoid transfer function have been used in the network. In addition, the statistical validity of the developed model has been determined by using the coefficient of determination (R{sup 2}), the root means square error (RMSE), and the relative absolute errors (RAE). R{sup 2}, RMSE and RAE have been determined for {delta}T as 0.9989, 0.5016, 0.0540 respectively. (author)

  11. Negative effect of smoking on the performance of the QuantiFERON TB gold in tube test

    DEFF Research Database (Denmark)

    Aabye, Martine G; Hermansen, Thomas Stig

    2012-01-01

    ABSTRACT: BACKGROUND: False negative and indeterminate Interferon Gamma Release Assay (IGRA) results are a well documented problem. Cigarette smoking is known to increase the risk of tuberculosis (TB) and to impair Interferon-gamma (IFN-gamma) responses to antigenic challenge, but the impact of smoking on IGRA performance is not known. The aim of this study was to evaluate the effect of smoking on IGRA performance in TB patients in a low and high TB prevalence setting respectively. METHODS: Patients with confirmed TB from Denmark (DK, n = 34; 20 smokers) and Tanzania (TZ, n = 172; 23 smokers) were tested with the QuantiFERON-TB Gold In tube (QFT). Median IFN-gamma level in smokers and non smokers were compared and smoking was analysed as a risk factor for false negative and indeterminate QFT results. RESULTS: Smokers from both DK and TZ had lower IFN-gamma antigen responses (median 0.9 vs. 4.2 IU/ml, p = 0.04 and 0.4 vs. 1.6, p <0.01), less positive (50 vs. 86%, p = 0.03 and 48 vs. 75%, p <0.01) and more false negative (45 vs. 0%, p <0.01 and 26 vs. 11%, p = 0.04) QFT results. In Tanzanian patients, logistic regression analysis adjusted for sex, age, HIV and alcohol consumption showed an association of smoking with false negative (OR 17.1, CI: 3.0-99.1, p <0.01) and indeterminate QFT results (OR 5.1, CI: 1.2-21.3, p = 0.02). CONCLUSIONS: Cigarette smoking was associated with false negative and indeterminate IGRA results in both a high and a low TB endemic setting independent of HIV status.

  12. Load characteristics of mechanical pectoral fin

    Science.gov (United States)

    Suzuki, Hiroyoshi; Kato, Naomi; Suzumori, Koichi

    2008-05-01

    This paper describes the use of a three-motor driven mechanical pectoral fin as a new device for maneuvering and stabilizing an underwater vehicle. The mechanical pectoral fin consists of three servomotors generating feathering, rowing, and flapping motions. The load properties are analyzed experimentally. The mechanical pectoral fin can generate a control load in three dimensions. The effect of flexibility of the fin on the load is also investigated experimentally.

  13. Fin efficiency analysis of convective straight fins with temperature dependent thermal conductivity using variational iteration method

    International Nuclear Information System (INIS)

    For enhancing heat transfer between primary surface and the environment, utilization of radiating extended surfaces are common. Especially for large temperature differences; variable thermal conductivity has a strong effect on performance of such a surface. In this paper, variational iteration method is used to analyze the efficiency of convective straight fins with temperature dependent thermal conductivity. VIM produces analytical expressions for the solution of nonlinear differential equations. In order to show the effectiveness of variational iteration method (VIM), the results obtained from VIM analysis is compared with available solutions obtained using Adomian decomposition method (ADM) and the results from finite element analysis. This work assures that VIM is a promising method for the efficiency analysis of convective straight fin problems

  14. Enteral Tube Feeding and Pneumonia

    Science.gov (United States)

    Gray, David Sheridan; Kimmel, David

    2006-01-01

    To determine the effects of enteral tube feeding on the incidence of pneumonia, we performed a retrospective review of all clients at our institution who had gastrostomy or jejunostomy tubes placed over a 10-year period. Ninety-three subjects had a history of pneumonia before feeding tube insertion. Eighty had gastrostomy and 13, jejunostomy…

  15. Effect of the sequence of tube rolling in a tube bundle of a shell and tube heat exchanger on the stress-deformed state of the tube sheet

    Science.gov (United States)

    Tselishchev, M. F.; Plotnikov, P. N.; Brodov, Yu. M.

    2015-11-01

    Rolling the tube sheet of a heat exchanger with U-shaped tubes, as exemplified by the vapor cooler GP-24, was simulated. The simulation was performed using the finite element method with account of elas- tic-plastic properties of the tube and tube sheet materials. The simulation consisted of two stages; at the first stage, maximum and residual contact stress in the conjunction of a separate tube and the tube sheet was determined using the "equivalent sleeve" model; at the second stage, the obtained contact stress was applied to the hole surface in the tube sheet. Thus, different tube rolling sequences were simulated: from the center to the periphery of the tube sheet and from the periphery to the center along a spiral line. The studies showed that the tube rolling sequence noticeably influences the value of the tube sheet residual deflection for the same rolling parameters of separate tubes. Residual deflection of the tube sheet in different planes was determined. It was established that the smallest residual deflection corresponds to the tube rolling sequence from the periphery to the center of the tube sheet. The following dependences were obtained for different rolling sequences: maximum deformation of the tube sheet as a function of the number of rolled tubes, residual deformation of the tube sheet along its surface, and residual deflection of the tube sheet as a function of the rotation angle at the periphery. The preferred sequence of tube rolling for minimizing the tube sheet deformation is indicated.

  16. Thrust production and wake structure of a batoid-inspired oscillating fin

    OpenAIRE

    Clark, R P; Smits, A.J.

    2006-01-01

    Experiments are reported on the hydrodynamic performance of a flexible fin. The fin replicates some features of the pectoral fin of a batoid fish (such as a ray or skate) in that it is actuated in a travelling wave motion, with the amplitude of the motion increasing linearly along the span from root to tip. Thrust is found to increase with non-dimensional frequency, and an optimal oscillatory gait is identified. Power consumption measurements lead to the computation of propulsive efficiency, ...

  17. A newton-Raphson method for calculating condenser performance based on the ASME single tube heat transfer data

    International Nuclear Information System (INIS)

    The calculation of condenser performance should include the response of the LP stage of the turbo-generator. The set of operating conditions for this subsystem, given a set of boundary conditions (e.g. MW load, cooling water inlet temperature and/or flow rate), recognizes the simultaneous presence of three heat transport mechanisms. Under steady state conditions, (1) the latent heat to be removed from the vapor equals (2) the amount of heat transferred through the thermal resistances consisting of the tube walls and film boundary layers; and this must also equal (3) the amount of heat acquired by the cooling water. This set of simultaneous equations is non-linear and is most readily solved by using the Newton-Raphson algorithm. With fossil plants the objective is to calculate the change in condenser duty due to fouling, given the present generated load. However, with nuclear plants the change in condenser duty now reflects a certain amount of generated power which has had to be foregone. In both cases, a reduction in condenser duty translates into a reduction in unit heat rate. With both types of plant there are a number of condenser configurations, including single compartment condensers with either single or double passes; and multi-compartment condensers, often with each compartment operating at a different pressure. Clearly, the equation set must be adjusted to take these variations into account. The attractiveness of the Newton-Raphson approach is that accurate loss estimates for any configuration can be achieved by merely modifying the set of variables and equations involved in the calculations, and adjusting the associated set of input/output data displays to suit. In this way the same basic software structure can be used to solve this whole family of problems

  18. Optimal design of plate-fin heat exchangers by a Bees Algorithm

    International Nuclear Information System (INIS)

    In this study, the application of Bees Algorithm (BA) in the optimum design of a cross flow plate-fin heat exchanger with offset strip fin is investigated. First, heat exchanger is optimized and designed according to the effectiveness optimization. Then, an analysis based on the second law of thermodynamics and minimizations of entropy generation units is performed. Specific heat duty, space restriction and permitted pressure drop are considered as the constraints for maximizing the effectiveness and minimizing the entropy generation units. Hot and cold flow length of the heat exchangers, number of fin layers, fin frequency, fin height, fin strip length and fin thickness are introduced as optimization variables. The effectiveness and accuracy of the suggested algorithm are compared with literature. The results have shown that BA can find optimum configuration with higher accuracy in comparison with Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Imperialist Competitive Algorithm (ICA) and preliminary design. - Highlights: •We analyzed a plate-fin heat exchanger with offset strip fins. •This is the first application of a Bees Algorithm for plate-fin heat exchanger design. •Preliminarily design and effectiveness of PFHE was improved by minimizing the entropy generation units. •The results show the superiority of this method over GA, PSO and ICA and preliminary design

  19. A novel nanoscale fin field effect transistor by amended channel: Investigation and fundamental physics

    Science.gov (United States)

    Karimi, Fa.; Orouji, Ali A.

    2015-11-01

    The present paper proposes a new Fin Field Effect Transistor (FinFET) with an amended Channel (AC). The fin region consists of two sections; the lower part which has a rounded shape and the upper part of fin as conventional FinFETs, is cubic. The AC-FinFET devices are proven to have a lower threshold voltage roll-off, reduced DIBL, better subthreshold slope characteristics, and a better gate capacitance in comparison with the C-FinFET. Moreover, the simulation result with three-dimensional and two-carrier device simulator demonstrates an improved output characteristic of the proposed structure due to reduction of self-heating effect. Due to the rounded shape of the lower fin region and decreasing corner effects there, the heat can flow easily, and the device temperature will decrease. Also the gate control over the channel increases due to the narrow upper part of the fin. The paper, thus, attempts to show the advantages of higher performance AC-FinFET device over the conventional one, and its effect on the operation of nanoscale devices.

  20. Fish Pectoral Fin Hydrodynamics; Part III: Low Dimensional Models via POD Analysis

    Science.gov (United States)

    Bozkurttas, M.; Madden, P.

    2005-11-01

    The highly complex kinematics of the pectoral fin and the resulting hydrodynamics does not lend itself easily to analysis based on simple notions of pitching/heaving/paddling kinematics or lift/drag based propulsive mechanisms. A more inventive approach is needed to dissect the fin gait and gain insight into the hydrodynamic performance of the pectoral fin. The focus of the current work is on the hydrodynamics of the pectoral fin of a bluegill sunfish in steady forward motion. The 3D, time-dependent fin kinematics is obtained via a stereo-videographic technique. We employ proper orthogonal decomposition to extract the essential features of the fin gait and then use CFD to examine the hydrodynamics of simplified gaits synthesized from the POD modes. The POD spectrum shows that the first two, three and five POD modes capture 55%, 67%, and 80% of the motion respectively. The first three modes are in particular highly distinct: Mode-1 is a ``cupping'' motion where the fin cups forward as it is abducted; Mode-2 is an ``expansion'' motion where the fin expands to present a larger area during adduction and finally Mode-3 involves a ``spanwise flick'' of the dorsal edge of the fin. Numerical simulation of flow past fin gaits synthesized from these modes lead to insights into the mechanisms of thrust production; these are discussed in detail.

  1. Replacement fin processing for III-V on Si: From FinFets to nanowires

    Science.gov (United States)

    Waldron, Niamh; Merckling, Clement; Teugels, Lieve; Ong, Patrick; Sebaai, Farid; Barla, Kathy; Collaert, Nadine; Thean, Voon-Yew (Aaron)

    2016-01-01

    In this paper we review the details and results of the replacement fin process technique used to successfully demonstrate InGaAs based channel devices from FinFets to ultra scaled nanowires on 300 mm Si substrates. For FinFet devices a Mg p-type doping solution was developed to counteract the unintentional n-type doping of the InP buffer layer which resulted in high source-drain leakage. However, the performance of these devices is found to be limited by the Mg doping as the mobility is degraded. By switching to a GAA architecture the problem of source-leakage through the InP buffer is effectively eliminated and best devices with LG = 60 nm have a peak transconductance of 1030 ?S/?m with a SSSAT of 125 mV/dec are achieved. A comparison of gate first to gate last processing highlights the importance of using a low thermal budget process to maintain the integrity of the InGaAs/high-K interface. Nanowires with a diameter of 6 nm were demonstrated to show quantization induced immunity to Dit resulting in a SSSAT as low as 66 mV/dec for 85 nm LG devices.

  2. ENERGY PERFORMANCE IMPROVEMENT, FLOW BEHAVIOR AND HEAT TRANSFER INVESTIGATION IN A CIRCULAR TUBE WITH V-DOWNSTREAM DISCRETE BAFFLES

    Directory of Open Access Journals (Sweden)

    Withada Jedsadaratanachai

    2013-01-01

    Full Text Available A mathematical study has been carried out to examine periodic laminar flow and heat transfer characteristics in a three-dimensional isothermal wall circular tube with 45° in-line V-discrete baffles. The computations are based on the Finite Volume Method (FVM and the SIMPLE algorithm has been implemented. The fluid flow and heat transfer characteristics are presented for Reynolds numbers based on the diameter of the circular tube ranging from 100 to 1200. To generate main streamwise vortex flows through the tested section, V-discrete baffles with an attack angle of 45° are mounted in tandem with in-line arrangement and pointing downstream (V-Downstream inserted in the middle of the tested tube. Effects of different Blockage Ratio (b/D, BR and Pitch Ratio (P/D, PR on heat transfer and pressure drop in the tube are studied. It is apparent that the main vortex flows can induce impinging flows on a wall of the interbaffle cavity leading to extreme increases in heat transfer rate over the circular tube. In addition, the rise in the BR and reduce of PR results in the increase in the Nusselt number and friction factor values. The computational results show that the optimum thermal enhancement factor is around 2.5 at BR = 0.15, PR = 1 and Re = 1200.

  3. Development of a high performance parallel computing platform and its use in the study of nanostructures: Clusters, sheets and tubes

    Science.gov (United States)

    Gowtham, S.

    Small clusters of gallium oxide, technologically important high temperature ceramic, together with interaction of nucleic acid bases with graphene and small-diameter carbon nanotube are focus of first principles calculations in this work. A high performance parallel computing platform is also developed to perform these calculations at Michigan Tech. First principles calculations are based on density functional theory employing either local density or gradient-corrected approximation together with plane wave and Gaussian basis sets. The bulk Ga2O3 is known to be a very good candidate for fabricating electronic devices that operate at high temperatures. To explore the properties of Ga2O3 at nanoscale, we have performed a systematic theoretical study on the small polyatomic gallium oxide clusters. The calculated results find that all lowest energy isomers of GamO n clusters are dominated by the Ga-O bonds over the metal-metal or the oxygen-oxygen bonds. Analysis of atomic charges suggest the clusters to be highly ionic similar to the case of bulk Ga2O3. In the study of sequential oxidation of these clusters starting from Ga3O, it is found that the most stable isomers display up to four different backbones of constituent atoms. Furthermore, the predicted configuration of the ground state of Ga2O is recently confirmed by the experimental results of Neumark's group. Guided by the results of calculations the study of gallium oxide clusters, performance related challenge of computational simulations, of producing high performance computers/platforms, has been addressed. Several engineering aspects were thoroughly studied during the design, development and implementation of the high performance parallel computing platform, RAMA, at Michigan Tech. In an attempt to stay true to the principles of Beowulf revolution, the RAMA cluster was extensively customized to make it easy to understand, and use - for administrators as well as end-users. Following the results of benchmark calculations and to keep up with the complexity of systems under study, RAMA has been expanded to a total of sixty four processors. Interest in the non-covalent interaction of DNA with carbon nanotubes has steadily increased during past several years. This hybrid system, at the junction of the biological regime and the nanomaterials world, possesses features which makes it very attractive for a wide range of applications. Using the in-house computational power available, we have studied details of the interaction between nucleic acid bases with graphene sheet as well as high-curvature small-diameter carbon nanotube. The calculated results find that the nucleic acid bases exhibited significantly different interaction strengths when physisorbed on graphene or carbon nanotube. The calculated trend in the binding energies strongly suggests that the polarizability of the base molecules determines the interaction strength of the nucleic acid bases with graphene. When comparing the results obtained here for physisorption on the small diameter nanotube considered with those from the study on graphene, it is observed that the interaction strength of nucleic acid bases is smaller for the tube. Thus, these results show that the effect of introducing curvature is to reduce the binding energy. The binding energies for the two extreme cases of negligible curvature (i.e. flat graphene sheet) and of very high curvature (i.e. small diameter nanotube) may be considered as upper and lower bounds. This finding represents an important step towards a better understanding of experimentally observed sequence-dependent interaction of DNA with carbon nanotubes.

  4. Numerical prediction of flow and heat transfer in a channel in the presence of a built-in circular tube with and without an integral wake splitter

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, S.; Chakraborty, D.; Biswas, G.; Panigrahi, P.K. [Indian Inst. of Technology, Kanpur (India). Dept. of Mechanical Engineering

    2005-01-01

    A numerical investigation was carried out to study the heat transfer behavior of a circular tube in cross-flow configuration with a longitudinal fin attached at the rear of the tube. The investigated configuration is intended to model either an element of a cross-flow heat exchanger or an element of the array of pin fins. The longitudinal finning of a circular tube is assumed to be in a configuration where the fin is attached at the back of the circular tube. The longitudinal fins, built-in with the tubes, are called integral splitter plates. The splitter plate creates a streamlined extension of the circular tube. It brings about enhancement of heat transfer from the tube surface. A reduction in the size of the wake zone in comparison with the wake of a circular tube is observed. Narrowing of the wake zone reduced convective heat transfer from the tube surface but the splitter plate itself generated an extra fin area for conduction. Overall, there is an improvement in heat transfer past the circular tube with an integral splitter plate compared with the case of flow past a circular tube without a splitter plate. Flow and heat transfer results are presented for three different chord lengths of the splitter plate and three different values of the Reynolds numbers (500, 1000 and 1500). The heat transfer enhancement obtained by finning was compared with that obtained by increasing the diameter of the unfinned tubes. (author)

  5. The performance study of the tube water wall PCCL and an experimental correlation for steam condensation in the presence of air under natural convection

    International Nuclear Information System (INIS)

    The object of this study was twofold. The first goal was to evaluate the thermal hydraulics performance of the tube water wall which is a proposed containment heat removal system for the Simplified Boiling Water Reactor (SBWR). The second goal was to develop a correlation for the condensation heat transfer coefficient of steam in the presence of various amounts of air. (author). 2 refs., 9 figs

  6. Dryout Quality for Refrigerants Flowing in Horizontal Evaporator Tubes

    Science.gov (United States)

    Mori, Hideo; Kakimoto, Yasushi; Ohishi, Katsumi

    The present paper reports an investigation of the dryout quality for refrigerants flowing in horizontal evaporator tubes. Experiments were made for the flow of boiling HFC-134a and HCFC-22 inside smooth tubes and a spirally grooved (micro-fin) tube. At given conditions, dryout proceeded over a certain quality range. Therefore two dryout qualities were defined; dryout inception quality at which the circumferentially averaged (axially local) heat transfer coefficient began to decrease rapidly, and dryout completion quality at which the decrease in the heat transfer coefficient ended. Based on the experimental data, the characteristics of both dryout qualities were clarified, and thereby the dryout qualities were classified into three characteristic regimes for the smooth tube and two regimes for the micro-fin tube. A dimensionless correlation of each dryout quality, which can reproduce the measurement successfully, was developed for the respective tubes.

  7. Thermohydraulic analysis of smooth and finned annular ducts

    International Nuclear Information System (INIS)

    The present work is concerned with the turbulent heat transfer and pressure drop in smooth and finned annular ducts overage heat transfer coefficients have been obtained by means of the heat exchanger theory. In addition, friction factors have also been determined. The experiments were performed by utilizing four double-pipe heat exchangers. The flowing fluids, in the heat exchangers, were air and water. The average heat transfer coefficients, for air flowing in the annular section, were determined by measuring the overall heat transfer coefficients of the heat exchangers. In order to attain fully developed conditions, the heat exchangers had a starting length of 30 hydraulic diameters. The thermal boundary conditions consisted of uniform temperature on the inner surface, the outer surface being insulated. The heat transfer coefficients and friction factors are presented in dimensionaless forms, as functions of the Reynolds number of the flow. The results for the smooth and finned annular ducts were compared. The purpose of such comparison was to study the influence of the fins on the pressure drop and heat transfer rate. In the case of the finned nular ducts, it is shown that the fin efficiency has some fluence on the heat transfer rates. The, a two-dimensional at transfer analysis was performed in order to obtain the n efficiency and the annular region efficiency. It is also shown that the overall thermal performance of finned surfaces epends mainly on the Nusselt number and on the region eficiency. These parameters are presented as functions of the Reynolds number of the flow and the geometry of the problem. (author)

  8. Collector Efficiency in Downward-Type Internal-Recycle Solar Air Heaters with Attached Fins

    Directory of Open Access Journals (Sweden)

    Chii-Dong Ho

    2013-10-01

    Full Text Available The internal-recycle operation effect on collector efficiency in downward-type rectangular solar air heaters with attached fins is theoretically investigated. It is found that considerable collector efficiency is obtainable if the collector has attached fins and the operation is carried out with internal recycling. The recycling operation increases the fluid velocity to decrease the heat transfer resistance, compensating for the undesirable effect of decreasing the heat transfer driving force (temperature difference due to remixing. The attached fins provide an enlarged heat transfer area. The order of performance in a device of same size is: double pass with recycle and fins > double pass with recycle but without fins > single pass without recycle and fins.

  9. Studying the effect of the shape parameters on the performance of the darrieus wind turbine using the multiple double disk stream tube theory

    International Nuclear Information System (INIS)

    The performance of the Darrieus vertical axis turbine is comparable with that of the more common horizontal axis machines. It has a number of aerodynamic and structural advantages over HAWTS. However the darrieus turbines are not self-starting at low wind speeds which is a considerable disadvantage for a simple small scale installation. Generally, papers concerning vertical axis turbine do not study the behavior of the rotor at low tip speed ratios. Therefore they do not deal with the self starting problems. A number of analytical methods were investigated to see whether they could predict the starting performance of vertical axis turbines. The chosen methods and 'actuator disc theory' for multiple stream tubes. In this paper the multiple stream tube model is applied using two discs in tandem. The computational analysis of all models simulates the blade aerodynamics throughout the full range of incidence from 180 degree centigrade. The effects of varying various geometric parameters of the windmill upon the performance of the rotor are investigated to find a design with improved self starting characteristics. The best agreement between theory and experiment was obtained using the multiple stream tube (double disc) models.(Author)

  10. Prospects for stronger calandria tubes

    International Nuclear Information System (INIS)

    The CANDU calandria tubes, made of seam welded and annealed Zircaloy-2, have given exemplary service in-reactor. Although not designed as a system pressure containment, calandria tubes may remain intact even in the face of pressure tube rupture. One such incident at Pickering Unit 2 demonstrated the economic advantage of such an outcome, and a case can be made for increasing the probability that other calandria tubes would perform in a similar fashion. Various methods of obtaining stronger calandria tubes are available, and reviewed here. When the tubes are internally pressurized, the weld is the weak section of the tube. Increasing the oxygen concentration in the starting sheet, and thickening the weld, are promising routes to a stronger tube

  11. Research on the Pin Fin Efficiency and Structure

    Directory of Open Access Journals (Sweden)

    Fan Bailin

    2013-06-01

    Full Text Available The performance of pin fin heat sink can be to measure through the temperature field. The temperature field and efficiency of the Pin Fin were analyzed, Pin fin efficiency curve was drowned also the distribution of the temperature field along the length of the pin fin curve was drawn. Thermal resistance was composed by thermal resistance of Aluminum substrate? thermal resistance of convective heat transfer and the thermal resistance of the cooling liquid. The change rule was studied through the calculation on Aluminum plate thermal resistance? thermal resistance of convective heat transfer and the thermal resistance of the cooling liquid. Its change regularity was simulated by toolbox In the MATLAB, and it was found that thermal resistance of convective heat transfer effect on the efficiency was most obvious in a certain amount of the heat and flow for thermal resistance of the Pin-fin radiator under the premise. The structural parameters of radiator were related to the size of thermal resistance.

  12. Control of a Supercavity-Piercing Fin

    Science.gov (United States)

    Syrstad, Justin

    2005-11-01

    Supercavitation provides a means of significantly reducing the drag of an underwater vehicle, thus enabling a dramatic increase in maximum speed. The control of supercavitating vehicles poses unique challenges. Only small regions at the nose (cavitator) and on the afterbody (fins) are in contact with water. Unlike for a fully wetted vehicle, there is an absence of lift on the body. Viable vehicle control options are limited to actuation of the cavitator and fins, and possibly thrust vectoring. Fin control is highly nonlinear due to the interaction of the fin with the cavity wall. Also, the cavity-fin interaction exhibits strong hysteresis effects. Tests were conducted in the high-speed water tunnel at St. Anthony Falls Laboratory with a semi-axisymmetric, ventilated cavity and a single wedged-shaped, 45 degree swept, cavity-piercing fin. Using a variety of fin control experiments, cavity stability and hysteresis effects were studied and compared to theoretical results. Fin torque was measured for different angles of attack with varying cavitation numbers. A closed-loop control experiment with fin responses to upstream/cavity disturbances is being carried out. Simulink models are being used to control the experimental setup and the measured parameters (fin position and torque) are compared to theoretical results.

  13. Influence of Chimney Width in Natural Convection Heat Transfer on a Vertical Finned Plate

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Jeyoung; Heo, Jeonghwan; Chung, Bumjin [Kyung Hee Univ., Yongin (Korea, Republic of)

    2014-05-15

    The RCCS adopts the chimney system to increase the flow rate. Also the fins installed in the inner walls of the chimney will provide an additional cooling performance by increasing the heat transfer area. On the other hand, the fins also increase the friction loss i. e. the pressure drop. Thus, in order to improve the heat transfer performance of the RCCS, an optimization among the fin parameters is necessary. Many experimental and numerical studies regarding the fin and the chimney are available. In this study, the natural convection heat transfer of the fin system located inside the chimney was measured. Based on the analogy concept, heat transfer experiments were replaced by mass transfer experiments using a sulfuric acid-copper sulfate (H{sub 2}SO{sub 4}-CuSO{sub 4}) electroplating system. The experiments were conducted by varying fin spacing, fin height, chimney width, and chimney height. This study experimentally investigated the natural convection heat transfer of the vertical finned plate in the chimney. Using an analogy, the heat transfer systems were replaced by mass transfer systems. The measured mass transfer coefficients was the difference with the existing heat transfer correlations due to the large value of the Pr, but exhibited similar trends with the existing heat transfer correlations. The heat transfer rate is increased by the decrease of the fin spacing and the increased fin height due to increased heat transfer area and chimney flow pattern. The chimney effect enhances heat transfer rate of vertical finned plate and the chimney effect on the Nu{sub s} In this study, the heat transfer rate on vertical finned plate in the chimney was confirmed by experiment for high values of Ra was stronger for the narrow chimney width, and became stronger by the higher chimney. The chimney effect was not observed when the chimney width becomes larger than a certain value depending on the Ra{sub s}.

  14. Effects of fin clipping on survival and position-holding behavior of brown darters, Etheostoma edwini

    Science.gov (United States)

    Champagne, C.E.; Austin, J.D.; Jelks, H.L.; Jordan, F.

    2008-01-01

    Advent of the polymerase chain reaction (PCR) has allowed conservation biologists to use small portions of tissue to obtain genetic material for population genetic and taxonomic study. Fin clips are used extensively in large-sized fishes, but it is unclear how clipping enough fin tissue for genetic analysis will affect survival of smaller fishes such as minnows and darters, which are among the most threatened organisms in North America. We tested for effects of fin clipping on survival and swimming performance of non-threatened Brown Darters (Etheostoma edwini) in order to justify similar tissue collection in co-occurring endangered Okaloosa Darters (E. okaloosae). We collected 48 E. edwini from a small stream in northwest Florida, transported them to the laboratory, and randomly assigned them to one of three experimental groups: control, entire right pectoral fin removed, or rear half of caudal fin removed. Successful amplification of DNA indicated that our fin clips were large enough for genetic analysis using PCR. No mortality occurred during a two-month observation period. Fin regeneration was almost complete and we could not visually distinguish clipped fins from control fins after two months. We then randomly assigned fish into the same three experimental groups, clipped fins, and evaluated their ability to hold position at 20 cm/sec in an experimental flow chamber. Neither fish size nor treatment type affected position-holding behavior. Fin clipping does not adversely affect survival and swimming performance of E. edwini maintained in the laboratory. Additional research on the effects of fin clipping on small-sized fishes should be conducted in the field to evaluate survival under natural conditions. ?? 2008 by the American Society of Ichthyologists and Herpetologists.

  15. Embedded SMA wire actuated biomimetic fin: a module for biomimetic underwater propulsion

    International Nuclear Information System (INIS)

    An embedded shape memory alloy (SMA) wire actuated biomimetic fin is presented, and based on this module for biomimetic underwater propulsion, a micro robot fish (146 mm in length, 30 g in weight) and a robot squid (242 mm in length, 360 g in weight) were developed. Fish swim by undulating their body and/or fins. Squid and cuttlefish can also swim by undulating their fins. To simplify engineering modeling, the undulating swimming movement is assumed to be the integration of the movements of many flexible bending segments connected in parallel or in series. According to this idea, a biomimetic fin which can bend flexibly was developed. The musculature of a cuttlefish fin was investigated to aid the design of the biomimetic fin. SMA wires act as 'muscle fibers' to drive the biomimetic fin just like the transverse muscles of the cuttlefish fin. During the bending phase, elastic energy is stored in the elastic substrate and skin, and during the return phase, elastic energy is released to power the return movement. Theorem analysis of the bending angle was performed to estimate the bending performance of the biomimetic fin. Experiments were carried out on single-face fins with latex rubber skin and silicone skin (SF-L and SF-S) to compare the bending angle, return time, elastic energy storage and reliability. Silicone was found to be the better skin. A dual-face fin with silicone skin (DF-S) was tested in water to evaluate the actuating performance and to validate the reliability. Thermal analysis of the SMA temperature was performed to aid the control strategy. The micro robot fish and robot squid employ one and ten DF-S, respectively. Swimming experiments with different actuation frequencies were carried out. The speed and steering radius of the micro robot fish reached 112 mm s?1 and 136 mm, respectively, and the speed and rotary speed of the robot squid reached 40 mm s?1 and 22° s?1, respectively

  16. Embedded SMA wire actuated biomimetic fin: a module for biomimetic underwater propulsion

    Science.gov (United States)

    Wang, Zhenlong; Hang, Guanrong; Wang, Yangwei; Li, Jian; Du, Wei

    2008-04-01

    An embedded shape memory alloy (SMA) wire actuated biomimetic fin is presented, and based on this module for biomimetic underwater propulsion, a micro robot fish (146 mm in length, 30 g in weight) and a robot squid (242 mm in length, 360 g in weight) were developed. Fish swim by undulating their body and/or fins. Squid and cuttlefish can also swim by undulating their fins. To simplify engineering modeling, the undulating swimming movement is assumed to be the integration of the movements of many flexible bending segments connected in parallel or in series. According to this idea, a biomimetic fin which can bend flexibly was developed. The musculature of a cuttlefish fin was investigated to aid the design of the biomimetic fin. SMA wires act as 'muscle fibers' to drive the biomimetic fin just like the transverse muscles of the cuttlefish fin. During the bending phase, elastic energy is stored in the elastic substrate and skin, and during the return phase, elastic energy is released to power the return movement. Theorem analysis of the bending angle was performed to estimate the bending performance of the biomimetic fin. Experiments were carried out on single-face fins with latex rubber skin and silicone skin (SF-L and SF-S) to compare the bending angle, return time, elastic energy storage and reliability. Silicone was found to be the better skin. A dual-face fin with silicone skin (DF-S) was tested in water to evaluate the actuating performance and to validate the reliability. Thermal analysis of the SMA temperature was performed to aid the control strategy. The micro robot fish and robot squid employ one and ten DF-S, respectively. Swimming experiments with different actuation frequencies were carried out. The speed and steering radius of the micro robot fish reached 112 mm s-1 and 136 mm, respectively, and the speed and rotary speed of the robot squid reached 40 mm s-1 and 22° s-1, respectively.

  17. Performance test results of mock-up model test facility with a full-scale reaction tube for HTTR hydrogen production system. Contract research

    Energy Technology Data Exchange (ETDEWEB)

    Inagaki, Yoshiyuki; Hayashi, Koji; Kato, Michio [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment] [and others

    2003-03-01

    Research on a hydrogen production system by steam reforming of methane, chemical reaction; CH{sub 4} + H{sub 2}O {yields} 3H{sub 2}O + CO, has been carried out to couple with the HTTR for establishment of high-temperature nuclear heat utilization technology and contribution to hydrogen energy society in future. The mock-up test facility with a full-scale reaction tube test facility, a model simulating one reaction tube of a steam reformer of the HTTR hydrogen production system in full scale, was fabricated to perform tests on controllability, hydrogen production performance etc. under the same pressure and temperature conditions as those of the HTTR hydrogen production system. The design and fabrication of the test facility started from 1997, and the all components were installed until September in 2001. In a performance test conducted from October in 2001 to February in 2002, performance of each component was examined and hydrogen of 120m{sup 3}{sub N}/h was successfully produced with high-temperature helium gas. This report describes the performance test results on components performance, hydrogen production characteristics etc., and main troubles and countermeasures. (author)

  18. Influence of Alumina Addition to Aluminum Fins for Compact Heat Exchangers Produced by Cold Spray Additive Manufacturing

    Science.gov (United States)

    Farjam, Aslan; Cormier, Yannick; Dupuis, Philippe; Jodoin, Bertrand; Corbeil, Antoine

    2015-10-01

    In this work, aluminum and aluminum-alumina powder mixtures were used to produce pyramidal fin arrays on aluminum substrates using cold spray as an additive manufacturing process. Using aluminum-alumina mixtures instead of pure aluminum powder could be seen as a cost-effective measure, preventing nozzle clogging or the need to use expensive polymer nozzles that wear out rapidly during cold spray. The fin geometries that were produced were observed using a 3D digital microscope to determine the flow passages width and fins' geometric details. Heat transfer and pressure drop tests were carried out using different ranges of appropriate Reynolds numbers for the sought commercial application to compare each fin array and determine the effect of alumina content. It was found that the presence of alumina reduces the fins' performance when compared to pure aluminum fins but that they were still outperforming traditional fins. Numerical simulations were performed to model the fin arrays and were used to predict the pressure loss in the fin array and compare these results with experimental values. The numerical model opens up new avenues in predicting different applicable operating conditions and other possible fin shapes using the same fin composition, instead of performing costly and time-consuming experiments.

  19. Influence of Alumina Addition to Aluminum Fins for Compact Heat Exchangers Produced by Cold Spray Additive Manufacturing

    Science.gov (United States)

    Farjam, Aslan; Cormier, Yannick; Dupuis, Philippe; Jodoin, Bertrand; Corbeil, Antoine

    2015-09-01

    In this work, aluminum and aluminum-alumina powder mixtures were used to produce pyramidal fin arrays on aluminum substrates using cold spray as an additive manufacturing process. Using aluminum-alumina mixtures instead of pure aluminum powder could be seen as a cost-effective measure, preventing nozzle clogging or the need to use expensive polymer nozzles that wear out rapidly during cold spray. The fin geometries that were produced were observed using a 3D digital microscope to determine the flow passages width and fins' geometric details. Heat transfer and pressure drop tests were carried out using different ranges of appropriate Reynolds numbers for the sought commercial application to compare each fin array and determine the effect of alumina content. It was found that the presence of alumina reduces the fins' performance when compared to pure aluminum fins but that they were still outperforming traditional fins. Numerical simulations were performed to model the fin arrays and were used to predict the pressure loss in the fin array and compare these results with experimental values. The numerical model opens up new avenues in predicting different applicable operating conditions and other possible fin shapes using the same fin composition, instead of performing costly and time-consuming experiments.

  20. Comparison between one-dimensional uncoupled and convection-conduction conjugated approaches in finned surface heat transfer

    Scientific Electronic Library Online (English)

    Cláudia R., Andrade; Edson L., Zaparoli.

    Full Text Available This work studies the forced convection problem in internal flow between concentric annular ducts, with radial fins at the internal tube surface. The finned surface heat transfer is analyzed by two different approaches. In the first one, it is assumed one-dimensional heat conduction along the intern [...] al tube wall and fins, with the convection heat transfer coefficient being a known parameter, determined by an uncoupled solution. In the other way, named conjugated approach, the mathematical model (continuity, momentum, energy and K-epsilon equations) applied to tube annuli problem was numerically solved using finite element technique in a coupled formulation. At first time, a comparison was made between results obtained for the conjugated problem and experimental data, showing good agreement. Then, the temperature profiles under these two approaches were compared to each other to analyze the validity of the one-dimensional classical formulation that has been utilized in the heat exchanger design.

  1. Parameter optimization through performance analysis of model based control of a batch heat treatment furnace with low NO x radiant tube burner

    International Nuclear Information System (INIS)

    A model based control structure for heat treating a 0.5% C steel slab in a batch furnace with low NO x radiant tube burner is designed and tested for performance to yield optimal parameter values using the model developed in the companion paper. Combustion is considered in a highly preheated and product gas diluted mode. Controlled combustion with a proposed arrangement for preheating and diluting the air by recirculating the exhaust gas that can be retrofitted with an existing burner yields satisfactory performance and emission characteristics. Finally, the effect of variable property considerations are presented and critically analyzed

  2. Thermal transport in oblique finned microminichannels

    CERN Document Server

    Fan, Yan; Singh, Pawan Kumar; Lee, Yong Jiun

    2015-01-01

    The main aim of this book is to introduce and give an overview of a novel, easy, and highly effective heat transfer augmentation technique for single-phase micro/minichannel heat sink. The specific objectives of the volume are to: Introduce a novel planar oblique fin microchannel and cylindrical oblique fin minichannel heat sink design using passive heat transfer enhancement techniques  Investigate the thermal transport in both planar and cylindrical oblique fin structures through numerical simulation and systematic experimental studies. Evaluate the feasibility of employing the proposed solution in cooling non-uniform heat fluxes and hotspot suppression Conduct the similarity analysis and parametric study to obtain empirical correlations to evaluate the total heat transfer rate of the oblique fin heat sink Investigate the flow mechanism and optimize the dimensions of cylindrical oblique fin heat sink Investigate the influence of edge effect on flow and temperature uniformity in these oblique fin chan...

  3. High-performance vacuum tubes for more energy efficiency. Building-integrated CPC vacuum tube collectors unite several functions.; Hochleistungs-Vakuumroehren fuer mehr Energieeffizienz. Gebaeudeintegrierte CPC-Vakuumroehren-Kollektoren vereinen mehrere Funktionen

    Energy Technology Data Exchange (ETDEWEB)

    Theiss, Eric

    2013-10-15

    The performance of solar collectors primarily contributes to increased efficiency and reduced operating costs of solar thermal systems. With the use of building-integrated CPC vacuum tube collectors an extremely high energy yield is achieved on a smaller collector gross area. As a building-integrated system solution the CPC facade provide panels in addition to its use as spandrel panels within the glazed buildings not only an architectural design element, but unite as a multifunctional component for several functions. [German] Die Leistungsfaehigkeit der Solarkollektoren traegt primaer zur Effizienzsteigerung und Reduzierung der Betriebskosten einer Solarthermieanlagen bei. Mit dem Einsatz gebaeudeintegrierter CPC-Vakuumroehrenkollektoren wird auf einer kleineren Kollektorbruttoflaeche ein extrem hoher Energieertrag erreicht. Als gebaeudeintegrierte Systemloesung bieten die CPC-Fassadenkollektoren neben dem Einsatz als Bruestungselemente auch innerhalb der verglasten Gebaeuden nicht nur ein architektonisches Gestaltungselement, sondern vereinen als multifunktionaler Bestandteil noch mehrere Funktionen.

  4. Coiled tubing

    Energy Technology Data Exchange (ETDEWEB)

    Curran, R.

    1999-03-01

    Continuous coiled tubing, which deploys a roll of steel pipe as the drill string off a huge spool, is described as one of the newer technologies that is gaining popularity in the Western Canadian Sedimentary Basin. In conjunction with underbalanced drilling systems which are used to limit damage in sensitive downhole formations, coiled tubing appears to have made the transition from experimental concept to commercial application. Although low oil prices have severely curtailed activities in the oilpatch throughout 1998, Haliburton Energy Services, a leading vendor of coiled tubing services, expects the demand for its services to remain reasonably steady during 1999, with coiled tubing technology even more dominant than it was last year. Coiled tubing drilling of vertical well extensions in low-pressure gas reservoirs are likely candidates for increased activity as a cold snap on the east coast of North America could increase demand for gas, and put pressure on producers to increase their gas production without major additional costs. Several variants of coiled tubing technology are described. One of these is Serval Integrated Energy Services` combination of coiled tubing injector and Maritime Hydraulics Ram Rig Concept, which was initially developed for offshore drilling. Coiled tubing deployed as a multi-point pressure and monitoring device called CT-MORE, for use with horizontal wells, was developed by PROMORE Engineering. In another development, a coil-deployed downhole submersible pump, developed by Petrospec Engineering and used exclusively by Caliber Coil Tubing Inc., is used to restore production in gas wells that have problems with liquid loading or have watered out.

  5. Physical Scaling Limits of FinFET Structure: A Simulation Study

    Directory of Open Access Journals (Sweden)

    Gaurav Saini

    2011-03-01

    Full Text Available In this work an attempt has been made to analyze the scaling limits of Double Gate (DG underlap andTriple Gate (TG overlap FinFET structure using 2D and 3D computer simulations respectively. Toanalyze the scaling limits of FinFET structure, simulations are performed using three variables: finthickness,fin-height and gate-length. From 2D simulation of DG FinFET, it is found that the gate-length(L and fin-thickness (Tfin ratio plays a key role while deciding the performance of the device. DrainInduced Barrier Lowering (DIBL and Subthreshold Swing (SS increase abruptly when (L/Tfin ratio goesbelow 1.5. So, there will be a trade-off in between SCEs and on- current of the device since on-off currentratio is found to be high at small dimensions. From 3D simulation study on TG FinFET, It is found thatboth fin-thickness (Tfin and fin-height (Hfin can control the SCEs. However, Tfin is found to be moredominant parameter than Hfin while deciding the SCEs. DIBL and SS increase as (Leff/Tfin ratiodecreases. The (Leff/Tfin ratio can be reduced below 1.5 unlike DG FinFET for the same SCEs. However,as this ratio approaches to 1, the SCEs can go beyond acceptable limits for TG FinFET structure. Therelative ratio of Hfin and Tfin should be maximum at a given Tfin and Leff to get maximum on-current perunit width. However, increasing Hfin degrades the fin stability and degrades SCEs.

  6. High temperature collecting performance of a new all-glass evacuated tubular solar air heater with U-shaped tube heat exchanger

    International Nuclear Information System (INIS)

    Highlights: • A novel solar air heater with simplified CPC and U-type heat exchanger is designed and tested. • The system is made up of 10 linked collecting panels. • Simplified CPC has a much lower cost at the expense of slight efficiency loss. • The air heater can propose the heated air exceeding 200 °C with great air flow rate. - Abstract: Experiment and simulation are conducted on a new-type all-glass evacuated tubular solar air heater with simplified compound parabolic concentrator (CPC). The system is made up of 10 linked collecting panels and each panel includes a simplified CPC and an all-glass evacuated tube with a U-shaped copper tube heat exchanger installed inside. Air is gradually heated when passing through each U-shaped copper tube. The heat transfer model of the solar air heater is established and the outlet air temperature, the heat power and heat efficiency are calculated. Calculated and experimental results show that the present experimental system can provide the heated air exceeding 200 °C. The whole system has an outstanding high-temperature collecting performance and the present heat transfer model can meet the general requirements of engineering calculations

  7. Experimental setup and the system performance for single-grid-based phase-contrast x-ray imaging (PCXI) with a microfocus x-ray tube

    Science.gov (United States)

    Lim, Hyunwoo; Park, Yeonok; Cho, Hyosung; Je, Uikyu; Hong, Daeki; Park, Chulkyu; Woo, Taeho; Lee, Minsik; Kim, Jinsoo; Chung, Nagkun; Kim, Jinwon; Kim, Jinguk

    2015-08-01

    In this work, we investigated a simplified approach to phase-contrast x-ray imaging (PCXI) by using a single antiscatter grid and a microfocus x-ray tube, which has potential to open the way to further widespread use of PCXI into the related application areas. We established a table-top setup for PCXI studies of biological and non-biological samples and investigated the system performance. The PCXI system consists of a focused-linear grid having a strip density of 200 lines/in. (JPI Healthcare Corp.), a microfocus x-ray tube having a focal spot size of about 5 ?m (Hamamatsu, L7910), and a high-resolution CMOS imaging detector having a pixel size of 48 ?m (Rad-icon Imaging Corp., Shad-o-Box 2048). By using our prototype system, we successfully obtained attenuation, scattering, and differential phase-contrast x-ray images of improved visibility from the raw images of several samples at x-ray tube conditions of 50 kVp and 6 mAs. Our initial results indicate that the single-grid-based approach seems a useful method for PCXI with great simplicity and minimal requirements on the setup alignment.

  8. Influence of Prandtl number and effects of disruption shape on the performance of enhanced tubes with the separation and reattachment mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Arman, B.; Rabas, T.J.

    1992-04-01

    The pressure-drop and heat-transfer performance of an enhanced tube with transverse disruptions can be predicted with a numerical modeling method, an accomplishment not previously achieved. Two computer codes were employed to achieve this goal - an orthogonal code and a nonorthogonal, body-fitted code. The turbulence closure was achieved with a two-layer turbulence model. The orthogonal computer code was used to determine the influence of the Prandti number. The numerical simulations demonstrated that six distinct regions exist and that three zones dominate the thermal performance. The nonorthogonal, body-fitted numerical code was used to determine the thermohydraulic performance of enhanced tubes with transverse, periodic sine-, semicircle-, arc-, and trapezoid-shaped disruptions. The research showed that there was a trade-off between the heat-transfer and pressure-drop performances when the disruption shape becomes more contoured, and that the local heat transfer is strongly dependent on the shape in the vicinity of the disruption, but it is less dependent in the downstream recirculation region and in the boundary-layer development zone.

  9. Influence of the receiver’s back surface radiative characteristics on the performance of a heat-pipe evacuated-tube solar collector

    International Nuclear Information System (INIS)

    Highlights: • A model for describing the heat transfer characteristics of the ETSC is derived. • A method by performing roughness treatment is proposed to change the emissivity. • Increasing the receiver’s back surface emissivity can greatly affect the heat loss. • Real weather test verifies the proposed method in controlling overheat phenomenon. - Abstract: The receiver’s back surface radiative characteristics of a heat-pipe evacuated-tube solar collector (ETSC) may have a significant influence on its performance. This influence is generally related to the back surface emissivity and temperature; however it has been not studied previously. This paper firstly presents a heat transfer model for the ETSC, which is then derived to characterize the relationship between the heat loss and the back surface emissivity of the ETSC. A steady state experiment has been also performed to measure the heat loss of ETSC with different back surface emissivity values. The experimental results indicate that the heat loss of the ETSC increases with the increase of the back surface emissivity, but the rate of increase differs for different operation temperatures. When the back surface emissivity increases from 0.03 to 0.12, the heat loss of ETSC only increases by 31% when the operation temperature is below 100 °C, but the heat loss will increase to 96% when the operation temperature is over 200 °C. This means that the change of back surface emissivity can significantly affect the performance of the ETSC at higher temperature but affect little at lower temperature. Based on this, a novel method by performing roughness treatment on the receiver’s back surface is proposed to solve the overheating problem of ETSC in summer. Two solar water heaters including 6 ETSCs with standard and roughness-treated tubes were tested under real weather condition. Experiment reveals that when the water temperature in tank is below 60 °C, the two solar water heaters own similar temperature change. But when the temperature is over 80 °C, the solar water heater with roughness-treated tube shows obviously lower temperature increase than that with standard tube. Therefore, it is very effective to prevent overheating of some solar water heaters used in high latitudes in summer by increasing the receiver’s back surface roughness

  10. Protective tubes for sodium heated water tubes

    International Nuclear Information System (INIS)

    A heat exchanger in which water tubes are heated by liquid sodium which minimizes the results of accidental contact between the water and the sodium caused by failure of one or more of the water tubes is described. A cylindrical protective tube envelopes each water tube and the sodium flows axially in the annular spaces between the protective tubes and the water tubes

  11. Reliability of steam generator tubing

    Energy Technology Data Exchange (ETDEWEB)

    Kadokami, E. [Mitsubishi Heavy Industries Ltd., Hyogo-ku (Japan)

    1997-02-01

    The author presents results on studies made of the reliability of steam generator (SG) tubing. The basis for this work is that in Japan the issue of defects in SG tubing is addressed by the approach that any detected defect should be repaired, either by plugging the tube or sleeving it. However, this leaves open the issue that there is a detection limit in practice, and what is the effect of nondetectable cracks on the performance of tubing. These studies were commissioned to look at the safety issues involved in degraded SG tubing. The program has looked at a number of different issues. First was an assessment of the penetration and opening behavior of tube flaws due to internal pressure in the tubing. They have studied: penetration behavior of the tube flaws; primary water leakage from through-wall flaws; opening behavior of through-wall flaws. In addition they have looked at the question of the reliability of tubing with flaws during normal plant operation. Also there have been studies done on the consequences of tube rupture accidents on the integrity of neighboring tubes.

  12. Study on antioxidant experiment on forged steel tube sheet and tube hole for steam generator

    International Nuclear Information System (INIS)

    Antioxidant experiment on forged steel tube sheet and tube hole for steam generator was studied and the influence of different simulated heat treatments on the antioxidant performance of tube sheet and tube hole was made. The influence of different antioxidant methods on the size of tube hole was drawn. Furthermore, the change of size and weight of 18MnD5 forged steel tube sheet on the condition of different simulated heat treatments was also studied. The analytical results have proved reference information for the use of 18MnD5 material and for key processes of processing tube hole and wearing and expanding U-style tube. (authors)

  13. Eddy current inspection of tubing

    International Nuclear Information System (INIS)

    The Experimental research work carried out to develop a Eddy current testing equipment is described. Search coils with ferrite or air cores were used and the obtained results are discussed. Valuable information was gained from a improved channel in which a direct measure of the defect and the reference signal phase difference is obtained. Artificial defect used to evaluate resolution and sensitivity were produced by electro-machining and mechanical means. Finned SAP tubing was tested in a routine basis with the described equipment and the results plotted. Basic and theoretical considerations on the Eddy current testing technique are given in the last section of this report. (Author)

  14. Steam generator tube integrity program

    Energy Technology Data Exchange (ETDEWEB)

    Dierks, D.R.; Shack, W.J. [Argonne National Laboratory, IL (United States); Muscara, J.

    1996-03-01

    A new research program on steam generator tubing degradation is being sponsored by the U.S. Nuclear Regulatory Commission (NRC) at Argonne National Laboratory. This program is intended to support a performance-based steam generator tube integrity rule. Critical areas addressed by the program include evaluation of the processes used for the in-service inspection of steam generator tubes and recommendations for improving the reliability and accuracy of inspections; validation and improvement of correlations for evaluating integrity and leakage of degraded steam generator tubes, and validation and improvement of correlations and models for predicting degradation in steam generator tubes as aging occurs. The studies will focus on mill-annealed Alloy 600 tubing, however, tests will also be performed on replacement materials such as thermally-treated Alloy 600 or 690. An overview of the technical work planned for the program is given.

  15. Convective–radiative radial fins with convective base heating and convective–radiative tip cooling: Homogeneous and functionally graded materials

    International Nuclear Information System (INIS)

    Highlights: • Convective–radiative radial fins with base convective heating were analyzed. • Homogeneous material and functionally graded material fins were investigated. • Fin efficiency and the effects of dimensionless parameters in fins were analyzed. - Abstract: This paper studies a radial fin of uniform thickness with convective heating at the base and convective–radiative cooling at the tip. The fin is assumed to experience uniform internal heat generation. The exposed surfaces of the fin lose heat by simultaneous convection and radiation to the surroundings. Two types of fin materials are investigated: homogeneous material and functionally graded material (FGM). For the homogeneous material, the thermal conductivity is assumed to be a linear function of temperature, while for the FGM fin the thermal conductivity is modeled as a linear function of the dimensionless radial coordinate. The analysis is conducted using the differential transformation method (DTM). The accuracy of DTM is verified by comparing the results for the simplified versions of the present model with an exact analytical solution derived here. Once the accuracy of DTM is authenticated, the method is used to generate results for the general problem formulated here. These results illustrate the effects of various dimensionless parameters on the thermal performance of homogeneous material fins and FGM fins

  16. Steam generator tube extraction

    International Nuclear Information System (INIS)

    To enable tube examination on steam generators in service, Framatome has now developed a process for removing sections of steam generator tubes. Tube sections can be removed without being damaged for treating the tube section expanded in the tube sheet

  17. Performance study on evacuated tube solar collector using therminol D-12 as heat transfer fluid coupled with parabolic trough

    International Nuclear Information System (INIS)

    Highlights: • Instant hot water at temperatures between 40 °C and 68 °C in the low solar radiation range of 240–540 W/m2. • Usage of therminol D-12 and parabolic trough in low temperature application. • Stability of thermal and flow properties of therminol D-12 are studied. - Abstract: Fossil fuels and electrical energy are widely used for instant hot water generation in rural and urban areas. Also, conventional solar water heaters do not support instant hot water generation because of various problems. A new system with evacuated tube collector using synthetic oil as heat transfer fluid coupled with parabolic trough is developed and studied experimentally for instant hot water generation in the presence of low solar irradiance. Among the different grades of therminol, therminol D-12 is chosen for the study because of its thermal stability. Parabolic trough is coupled to evacuated tube to enhance the flow as well as heating characteristics of therminol. Heating efficiency and temperature characteristics are determined for the newly developed system under low solar irradiance conditions. Instant hot water can be produced by the new system at a temperature of 60 °C in the presence of low solar radiation. This newly developed system has the ability to check the fossil fuel consumption and electrical energy consumption for instant hot water generation in household applications. The stability of the heat transfer fluid is also ensured by repeated experiments

  18. Performance of a reciprocal shaker in mechanical dispersion of soil samples for particle-size analysis / Avaliação do desempenho de mesa agitadora reciprocante na dispersão de amostras de solo para fins de análise granulométrica

    Scientific Electronic Library Online (English)

    Thayse Aparecida, Dourado; Laura Fernanda Simões da, Silva; Mara de Andrade, Marinho.

    2012-08-01

    Full Text Available A dispersão da amostra de solo é uma etapa fundamental da análise granulométrica, sendo realizada mediante o uso de dispersantes químicos e agitação mecânica. O objetivo deste trabalho foi avaliar a eficiência de mesa agitadora reciprocante de baixa rotação na dispersão mecânica de amostras de solos [...] de diferentes classes texturais. Foram realizadas análises granulométricas em 61 amostras com quatro repetições, empregando o método da pipeta para determinação da fração argila e tamisagem para determinação das frações areia grossa, areia fina e areia total, sendo o silte determinado por diferença. Na avaliação de desempenho, os resultados obtidos com uso da mesa agitadora reciprocante (MAR) foram comparados com dados disponíveis para as mesmas amostras oriundos de relatórios do Ensaio de Proficiência IAC para Laboratórios de Análises de Solos - Prolab/IAC. Análises de acurácia foram realizadas com base nos valores dos intervalos de confiança definidos para cada fração granulométrica componente de cada amostra ensaiada. Indicadores gráficos também foram utilizados na comparação de dados, por meio de dispersão e ajuste linear. A estatística descritiva indicou preponderância de baixa variabilidade em mais de 90 % dos resultados obtidos para as amostras de texturas arenosa, média e argilosa e em 68 % dos obtidos para as amostras de textura muito argilosa, indicando boa repetibilidade dos resultados obtidos com a MAR. Média variabilidade foi mais frequentemente associada à fração silte, seguida da fração areia fina. Os resultados das análises de sensibilidade indicam acurácia de 100 % nas três frações granulométricas - areia total, silte e argila - para todas as amostras analisadas pertencentes às classes texturais muito argilosa, argilosa e média. Para as nove amostras de textura arenosa, a acurácia média foi de 85,2 %, e os maiores desvios ocorreram em relação à fração silte. Nas aproximações lineares, coeficientes de correlação igual (silte) ou superiores (areia total e argila) a 0,93, bem como diferenças menores do que 0,16 entre os coeficientes angulares das retas e o valor unitário, indicam alta correlação entre os resultados de referência (Prolab/IAC) e os obtidos nos ensaios com a MAR. Conclui-se pelo desempenho satisfatório da mesa agitadora reciprocante de baixa rotação para dispersão mecânica de amostras de solo de diferentes classes texturais para fins de análise granulométrica, permitindo recomendar o uso alternativo do equipamento quando se emprega agitação lenta. As vantagens do uso do equipamento nacional incluem o baixo custo, a possibilidade de análise simultânea de grande número de amostras e o uso de frascos comuns, de vidro ou de plástico, baratos e de fácil reposição. Abstract in english The dispersion of the samples in soil particle-size analysis is a fundamental step, which is commonly achieved with a combination of chemical agents and mechanical agitation. The purpose of this study was to evaluate the efficiency of a low-speed reciprocal shaker for the mechanical dispersion of so [...] il samples of different textural classes. The particle size of 61 soil samples was analyzed in four replications, using the pipette method to determine the clay fraction and sieving to determine coarse, fine and total sand fractions. The silt content was obtained by difference. To evaluate the performance, the results of the reciprocal shaker (RSh) were compared with data of the same soil samples available in reports of the Proficiency testing for Soil Analysis Laboratories of the Agronomic Institute of Campinas (Prolab/IAC). The accuracy was analyzed based on the maximum and minimum values defining the confidence intervals for the particle-size fractions of each soil sample. Graphical indicators were also used for data comparison, based on dispersion and linear adjustment. The descriptive statistics indicated predominantly low variability in more than 90 % of the results for sand, medium-textured and cla

  19. Mechanical Properties of Cold Gas Dynamic-Sprayed Near-Net-Shaped Fin Arrays

    Science.gov (United States)

    Cormier, Yannick; Dupuis, Philippe; Jodoin, Bertrand; Corbeil, Antoine

    2015-02-01

    This work focuses on the study of the adhesion and thermal performance of near-net-shaped pyramidal fin arrays manufactured by cold spray on aluminum alloy substrate coated with various bond coats: a cold-sprayed bond coat as well as nitrogen- and air-propelled arc-sprayed bond coats. Furthermore, the effects of the fin density, fin height, and substrate surface roughness on the adhesion strength of the fins deposited on Al6061 substrates were characterized. It was found that the fin density, the fin height, and the substrate roughness have little impact on the adhesion strength of this system. The adhesion strength was found to be inversely proportional to the surface hardness when investigating these parameters for the different thermal-spray bond coatings, with all the fin systems having a much greater strength than the theoretical application stresses. Finally, it was found that the increase in the fin's base layer's roughness increases the overall heat transfer, with the bond coat material having a negligible effect on the thermal resistance for this type of heat-exchanger configuration.

  20. Automated attenuation-based tube voltage selection for body CTA: Performance evaluation of 192-slice dual-source CT

    Energy Technology Data Exchange (ETDEWEB)

    Winklehner, Anna; Gordic, Sonja; Lauk, Eliane; Frauenfelder, Thomas; Alkadhi, Hatem; Husarik, Daniela B. [University Hospital Zurich, Institute for Diagnostic and Interventional Radiology, Zurich (Switzerland); Leschka, Sebastian [University Hospital Zurich, Institute for Diagnostic and Interventional Radiology, Zurich (Switzerland); Division of Radiology and Nuclear Medicine, St. Gallen (Switzerland)

    2015-08-15

    To assess radiation dose and image quality in body CT-angiography (CTA) with automated attenuation-based tube voltage selection (ATVS) on a 192-slice dual-source CT (DSCT). Forty patients (69.5 ± 9.6 years) who had undergone body CTA with ATVS (ref.kVp 100, ref.mAs 90) using a 2x192-slice CT in single-source mode were retrospectively included. All patients had undergone prior CTA with a 2x128-slice CT and ATVS with identical imaging and contrast media protocols, serving for comparison. Images were reconstructed with iterative reconstruction at similar strength levels. Radiation dose was determined. Image quality was assessed semi-quantitatively (1:excellent, 5:non-diagnostic), aortic attenuation, noise and CNR were determined. As compared to 128-slice DSCT, 192-slice DSCT selected tube voltages were lower in 30 patients (75 %), higher in 3 (7.5 %), and similar in 7 patients (17.5 %). CTDI{sub vol} was lower with 192-slice DSCT (4.7 ± 1.9 mGy vs. 5.8 ± 2.1 mGy; p < 0.001). Subjective image quality, mean aortic attenuation (342 ± 67HU vs. 268 ± 67HU) and CNR (9.8 ± 2.5 vs. 8.2 ± 2.9) were higher with 192-slice DSCT (all p < 0.01), all datasets being diagnostic. Our study suggests that ATVS of 192-slice DSCT for body CTA is associated with an improved image quality and further radiation dose reduction of 19 % compared to 128-slice DSCT. (orig.)

  1. Automated attenuation-based tube voltage selection for body CTA: Performance evaluation of 192-slice dual-source CT

    International Nuclear Information System (INIS)

    To assess radiation dose and image quality in body CT-angiography (CTA) with automated attenuation-based tube voltage selection (ATVS) on a 192-slice dual-source CT (DSCT). Forty patients (69.5 ± 9.6 years) who had undergone body CTA with ATVS (ref.kVp 100, ref.mAs 90) using a 2x192-slice CT in single-source mode were retrospectively included. All patients had undergone prior CTA with a 2x128-slice CT and ATVS with identical imaging and contrast media protocols, serving for comparison. Images were reconstructed with iterative reconstruction at similar strength levels. Radiation dose was determined. Image quality was assessed semi-quantitatively (1:excellent, 5:non-diagnostic), aortic attenuation, noise and CNR were determined. As compared to 128-slice DSCT, 192-slice DSCT selected tube voltages were lower in 30 patients (75 %), higher in 3 (7.5 %), and similar in 7 patients (17.5 %). CTDIvol was lower with 192-slice DSCT (4.7 ± 1.9 mGy vs. 5.8 ± 2.1 mGy; p < 0.001). Subjective image quality, mean aortic attenuation (342 ± 67HU vs. 268 ± 67HU) and CNR (9.8 ± 2.5 vs. 8.2 ± 2.9) were higher with 192-slice DSCT (all p < 0.01), all datasets being diagnostic. Our study suggests that ATVS of 192-slice DSCT for body CTA is associated with an improved image quality and further radiation dose reduction of 19 % compared to 128-slice DSCT. (orig.)

  2. Design & modelling of a composite rudderless aeroelastic fin structure

    OpenAIRE

    Trapani, Matteo

    2010-01-01

    This thesis presents the study of a gapless and rudderless aeroelastic fin (GRAF) to enhance the directional stability and controllability of an aircraft. The GRAF concept was proposed and developed in the wake of previous research, targeted to improve flight performance and manoeuvrability, and to reduce fuel consumption and airframe weight. The study involved the subjects of aerodynamics, structural design and analysis, and flight mechanics. The work includes conceptual de...

  3. Performance investigation of a hospital-grade x-ray tube-based differential phase-contrast cone beam CT system

    Science.gov (United States)

    Yu, Yang; Ning, Ruola; Cai, Weixing; Liu, Jiangkun; Conover, David

    2012-03-01

    Differential phase contrast technique could be the next breakthrough in the field of CT imaging. While traditional absorption-based X-ray CT imaging is inefficient at differentiating soft tissues, phase-contrast technique offers great advantage as being able to produce higher contrast images utilizing the phase information of objects. Our long term goal is to develop a gantry-based hospital-grade X-ray tube differential phase contrast cone-beam CT (DPC-CBCT) technology which is able to achieve higher contrast noise ratio (CNR) in soft tissue imaging without increasing the dose level. Based on the micro-focus system built last year, a bench-top hospital-grade X-ray tube DPC-CBCT system is designed and constructed. The DPC-CBCT system consists of an X-ray source, i.e. a hospital-grade X-ray tube and a source grating, a high-resolution detector, a rotating phantom holder, a phase grating and an analyzer grating. Threedimensional (3-D) phase-coefficients are reconstructed, providing us with images enjoying higher CNR than, yet equivalent dose level to, a conventional CBCT scan. Three important aspects of the system are investigated: a) The The system's performance in term of CNR of the reconstruction image with regard to dose levels, b) the impacts of different phase stepping schemes, i.e. 5 steps to 8 steps, in term of CNR on the reconstruction images, and c) the influence of magnification or position of the phantom on image quality, chiefly CNR. The investigations are accomplished via phantom study.

  4. FLOW DISTRIBUTION IN A SOLAR COLLECTOR PANEL WITH HORIZONTAL FINS

    DEFF Research Database (Denmark)

    Fan, Jianhua; Shah, Louise Jivan

    2005-01-01

    The objective of this work is to theoretically and experimentally investigate the flow and temperature distribution in a solar collector panel with an absorber consisting of horizontal fins. Fluid flow and heat transfer in the collector panel are studied by means of computational fluid dynamics (CFD) calculations. Further, experimental investigations of a 12.5 m² solar collector panel with 16 parallel connected horizontal fins are carried out. The flow distribution through the absorber is evaluated by means of temperature measurements on the backside of the absorber tubes. The measured temperatures are compared to the temperatures determined by the CFD model and there is a good similarity between the measured and calculated results. Calculations with the CFD model elucidate the flow and temperature distribution in the collector. The influences of operating conditions such as flow rate, temperature of inlet flow and collector tilt angle are shown. Based on the investigations preliminary recommendations for theoperation of the investigated collector are given. For instance, minimum flow rate in order to avoid boiling in the horizontal strips is recommended.

  5. Fin shape thermal optimization using Bejan's constuctal theory

    CERN Document Server

    Lorenzini, Giulio

    2011-01-01

    The book contains research results obtained by applying Bejan's Constructal Theory to the study and therefore the optimization of fins, focusing on T-shaped and Y-shaped ones. Heat transfer from finned surfaces is an example of combined heat transfer natural or forced convection on the external parts of the fin, and conducting along the fin. Fin's heat exchange is rather complex, because of variation of both temperature along the fin and convective heat transfer coefficient. Furthermore possible presence of more fins invested by the same fluid flow has to be considered.Classical fin theory tri

  6. FinROSE - middle atmospheric chemistry transport model

    Energy Technology Data Exchange (ETDEWEB)

    Damski, J.; Thoelix, L.; Backman, L. (Research and Development, Finnish Meteorological Inst., Helsinki (FI)); Taalas, P. (Regional and Technical Cooperation for Development Dept. World Meteorological Organization, Geneve (CH)); Kulmala, M. (Helsinki Univ. (FI). Div. of Atmospheric Sciences)

    2007-07-01

    The development and performance of a three-dimensional global middle atmospheric chemistry transport model FinROSE is described. The FinROSE chemistry transport model includes a numerical scheme for stratospheric chemistry with parameterizations for heterogeneous processing on polar stratospheric clouds (PSC) and on liquid binary aerosols together with a parameterisation of large nitric acid trihydrate particles (i.e. NAT-rocks) and PSC sedimentation. The total number of trace species in the model is 34 and the total number of gas-phase reactions, photodissociation processes and heterogeneous reactions is about 150. The model is forced by external wind and temperature fields. The simulations are normally performed in a 5 deg x 10 deg (lat. x long.) grid from the surface up to around 0.1 hPa, with a vertical resolution of ca. 1.5 km in the stratosphere. Long-term simulations (40 to 50 years) have been done using winds and temperatures from ECMWF ERA40 analyses. The performance of the model in describing the stratospheric composition and chemistry is shown and evaluated in this paper. In general, the FinROSE results show a good comparison with measured total ozone. Also the timing, the depth and the deepening of the Antarctic ozone hole, and the responsible processes are captured well in the model simulations. (orig.)

  7. An experimental investigation into the deployment of 3-D, finned wing and shape memory alloy vortex generators in a forced air convection heat pipe fin stack

    International Nuclear Information System (INIS)

    Forced air convection heat pipe cooling systems play an essential role in the thermal management of electronic and power electronic devices such as microprocessors and IGBT's (Integrated Gate Bipolar Transistors). With increasing heat dissipation from these devices, novel methods of improving the thermal performance of fin stacks attached to the heat pipe condenser section are required. The current work investigates the use of a wing type surface protrusions in the form of 3-D delta wing tabs adhered to the fin surface, thin wings punched-out of the fin material and TiNi shape memory alloy delta wings which changed their angles of attack based on the fin surface temperature. The longitudinal vortices generated from the wing designs induce secondary mixing of the cooler free stream air entering the fin stack with the warmer fluid close to the fin surfaces. The change in angle of the attack of the active delta wings provide heat transfer enhancement while managing flow pressure losses across the fin stack. A heat transfer enhancement of 37% compared to a plain fin stack was obtained from the 3-D tabs in a staggered arrangement. The punched-out delta wings in the staggered and inline arrangements provided enhancements of 30% and 26% respectively. Enhancements from the active delta wings were lower at 16%. However, as these devices reduce the pressure drop through the fin stack by approximately 19% in the de-activate position, over the activated position, a reduction in fan operating cost may be achieved for systems operating with inlet air temperatures below the maximum inlet temperature specification for the device. CFD analysis was also carried out to provide additional detail of the local heat transfer enhancement effects. The CFD results corresponded well with previously published reports and were consistent with the experimental findings. - Highlights: ? Heat transfer enhancements of heat pipe fin stacks was successfully achieved using fixed and active delta wing vortex generators. ? The active vortex generators, made from Ti-Ni, protruded into the flow stream at high temperatures and resume a low profile position at a low temperature set point. ? By considering wing spacing and the distance from the leading edge of the fin stack, heat transfer enhancements of up to 37%, compared to plane fin stacks, were achieved. ? By replacing the fixed delta wings with the active vortex generators, heat transfer enhancements of up to 16% was achieved and the pressure loss associated with flow obstructions was effectively managed.

  8. Pectoral fins and paternal quality in sticklebacks.

    OpenAIRE

    Künzler, R; Bakker, T C

    2000-01-01

    Sexual selection through female mate choice exerts a strong selection pressure on males' sexual traits, particularly when direct benefits are involved. In species with male parental care, one would expect sexual selection to favour paternal quality, for instance through selection on morphological structures which promote quality. We experimentally studied the influence of pectoral fins on paternal quality in male three-spined sticklebacks (Gasterosteus aculeatus L.). After reductions of fin a...

  9. The use of pelvic fins for benthic locomotion during foraging behavior in Potamotrygon motoro (Chondrichthyes: Potamotrygonidae)

    Scientific Electronic Library Online (English)

    Akemi, Shibuya; Marcelo R. de, Carvalho; Jansen, Zuanon; Sho, Tanaka.

    2015-06-01

    Full Text Available Synchronized bipedal movements of the pelvic fins provide propulsion (punting) during displacement on the substrate in batoids with benthic locomotion. In skates (Rajidae) this mechanism is mainly generated by the crural cartilages. Although lacking these anatomical structures, some stingray species [...] show modifications of their pelvic fins to aid in benthic locomotion. This study describes the use of the pelvic fins for locomotory performance and body re-orientation in the freshwater stingray Potamotrygon motoro (Müller & Henle, 1841) during foraging. Pelvic fin movements of juvenile individuals of P. motoro were recorded in ventral view by a high-speed camera at 250-500 fields/s-1. Potamotrygon motoro presented synchronous, alternating and unilateral movements of the pelvic fins, similar to those reported in skates. Synchronous movements were employed during straightforward motion for pushing the body off the substrate as well as for strike feeding, whereas unilateral movements were used to maneuver the body to the right or left during both locomotion and prey capture. Alternating movements of the pelvic fins are similar to bipedal movements in terrestrial and semi-aquatic tetrapods. The pelvic fins showed coordinated movements during feeding even when stationary, indicating that they have an important function in maintaining body posture (station holding) during prey capture and manipulation. The use of pelvic fins during prey stalking may be advantageous because it results in less substrate disturbance when compared to movements generated by pectoral fin undulation. The range of pelvic fin movements indicates more complex control and coordination of the pelvic radial muscles.

  10. Fin development in stream- and hatchery-reared Atlantic salmon

    Science.gov (United States)

    Pelis, R.M.; McCormick, S.D.

    2003-01-01

    To determine the effect of development and environment on fin growth, we measured fin lengths of juvenile Atlantic salmon (Salmo salar) from two hatcheries (August, October and April-May), stream-reared fish (July and October) stocked as fry into two tributaries, and smelts from the main stem of the Connecticut River (May). For stream-reared parr, there was a linear relationship between the dorsal, caudal and anal fins with fork length, while the pectoral, pelvic and adipose fins exhibited a curvilinear relationship with fork length. Parr from a high gradient stream had larger caudal fins than fish from a low gradient stream, but other fins did not differ. Regression lines for the fins of stream-reared smelts were all linear when fin length was regressed against fork length. Stream-reared parr had larger pectoral, pelvic and anal fins than smolts of similar size while dorsal and caudal fin lengths did not differ. Regression equations formulated using the fins of stream-reared parr were used to calculate the percent difference (100 x observed fin length/expected) in fin lengths between stream- and hatchery-reared parr. The pelvic, adipose, caudal and anal fins of hatchery-reared parr showed no signs of degeneration by the first sampling period 7 months after hatching, whereas degeneration in the pectoral (13-20%) and dorsal (15-18%) fins was evident at this time. By the end of the study, degeneration was present in every fin except the adipose, with the pectoral (35-65%) and dorsal (32-58%) fins exhibiting the greatest amount of fin loss. All fins of hatchery-reared parr became shorter with time. There were minor differences in fin degeneration among parr from the two hatcheries, but the overall pattern of decreasing fin size was similar, indicating a common cause of fin degeneration. Comparison of stream- and hatchery-reared fish is a valuable means of determining the impact of captive environments on fin growth.

  11. Computational heat transfer analysis and combined ANN–GA optimization of hollow cylindrical pin fin on a vertical base plate

    Indian Academy of Sciences (India)

    C Balachandar; S Arunkumar; M Venkatesan

    2015-09-01

    In the devices like laptops, microprocessors, the electric circuits generate heat while performing work which necessitates the use of fins. In the present work, the heat transfer characteristics of hollow cylindrical pin fin array on a vertical rectangular base plate is studied using commercial CFD code ANSYS FLUENT© . The hollow cylindrical pin fins are arranged inline. The heat transfer augmentation is studied for different parameters such as inner radius, outer radius, height of the fins and number of pin fins. The base plate is supplied with a constant heat flux in the range of 20–500W. The base plate dimensions are kept constant. The base plate temperature is predicted using Artificial Neural Network (ANN) by training the network based on the results of numerical simulation. The trained ANN is used to analyse the fin in terms of enhanced heat transfer and weight reduction when compared to solid pin fin. Optimization of the hollow cylindrical pin fin parameters to obtain maximum heat transfer from the base plate is carried out using Genetic Algorithm (GA) applied on the trained neural network. The analysis using the numerical simulation and neural network shows that the hollow fins provide an increased heat transfer and a weight reduction of about 90% when compared to solid cylindrical pin fins.

  12. Template-assisted formation of microsized nanocrystalline CeO(2) tubes and their catalytic performance in the carboxylation of methanol.

    Science.gov (United States)

    Schneider, Jörg J; Naumann, Meike; Schäfer, Christian; Brandner, Armin; Hofmann, Heiko J; Claus, Peter

    2011-01-01

    Polymethylmethacrylate (PMMA)/ceria composite fibres were synthesized by using a sequential combination of polymer electrospinning, spray-coating with a sol, and a final calcination step to yield microstructured ceria tubes, which are composed of nanocrystalline ceria particles. The PMMA template is removed from the organic/inorganic hybrid material by radio frequency (rf) plasma etching followed by calcination of the ceramic green-body fibres. Microsized ceria (CeO(2)) tubes, with a diameter of ca. 0.75 µm, composed of nanocrystalline agglomerated ceria particles were thus obtained. The 1-D ceramic ceria material was characterized by X-ray diffraction, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), UV-vis and photoluminescence spectroscopy (PL), as well as thermogravimetric analysis (TGA). Its catalytic performance was studied in the direct carboxylation of methanol with carbon dioxide leading to dimethyl carbonate [(CH(3)O)(2)CO, DMC], which is widely employed as a phosgene and dimethyl sulfate substitute, and as well as a fuel additive. PMID:22259761

  13. Template-assisted formation of microsized nanocrystalline CeO2 tubes and their catalytic performance in the carboxylation of methanol

    Directory of Open Access Journals (Sweden)

    Jörg J. Schneider

    2011-11-01

    Full Text Available Polymethylmethacrylate (PMMA/ceria composite fibres were synthesized by using a sequential combination of polymer electrospinning, spray-coating with a sol, and a final calcination step to yield microstructured ceria tubes, which are composed of nanocrystalline ceria particles. The PMMA template is removed from the organic/inorganic hybrid material by radio frequency (rf plasma etching followed by calcination of the ceramic green-body fibres. Microsized ceria (CeO2 tubes, with a diameter of ca. 0.75 µm, composed of nanocrystalline agglomerated ceria particles were thus obtained. The 1-D ceramic ceria material was characterized by X-ray diffraction, scanning electron microscopy (SEM, high-resolution transmission electron microscopy (HRTEM, UV–vis and photoluminescence spectroscopy (PL, as well as thermogravimetric analysis (TGA. Its catalytic performance was studied in the direct carboxylation of methanol with carbon dioxide leading to dimethyl carbonate [(CH3O2CO, DMC], which is widely employed as a phosgene and dimethyl sulfate substitute, and as well as a fuel additive.

  14. Drift tube beam blocking experiments performed on the ORNL/PLT neutral beam line at the ORNL medium energy test facility

    International Nuclear Information System (INIS)

    The Fusion Energy Division of the Oak Ridge National Laboratory (ORNL) in cooperation with the Princeton Plasma Physics Laboratory (PPPL) designed, constructed, and tested four high power neutral beam injectors for application on the Princeton Large Torus (PLT). This system employs a modified duoPIGatron ion source which has produced ion beams with parameters up to 70 A, 45 keV, and 500 msec. Nominal extraction parameters were 60-A, 40-keV, and 300-msec pulses, simultaneously. Neutral power up to 750 kW for 100 msec was calorimetrically measured on a simulated PLT target behind a PLT-sized aperture of 20 x 25 cm located at 4.10 m. Initial performance of these beam lines on PLT was near these parameters. Calorimetric measurements of beam power delivered to the PLT torus with a 3.65-m beam line length and with 100-msec full power pulses indicate a 10 to 15% reionization loss when the beam line pulse is synchronized to the pulsed torus magnetic fields. Data taken at ORNL are presented to show that this power loss is approximately equal to that calculated on drift tube pressure measurements taken without drift tube magnetic fields

  15. Collector Efficiency in Downward-Type Double-Pass Solar Air Heaters with Attached Fins and Operated by External Recycle

    Directory of Open Access Journals (Sweden)

    Chii-Dong Ho

    2012-07-01

    Full Text Available The collector efficiency in a downward-type double-pass external-recycle solar air heater with fins attached on the absorbing plate has been investigated theoretically. Considerable improvement in collector efficiency is obtainable if the collector is equipped with fins and the operation is carried out with an external recycle. Due to the recycling, the desirable effect of increasing the heat transfer coefficient compensates for the undesirable effect of decreasing the driving force (temperature difference of heat transfer, while the attached fins provide an enlarged heat transfer area. The order of performances in the devices of same size is: double pass with recycle and fins > double pass with recycle but without fins > single pass without recycle and fins.

  16. Necropsy report of a fin whale (Balaenoptera physalus) stranded in Denmark in 2010

    DEFF Research Database (Denmark)

    Alstrup, Aage K. O.; Hedayat, Abdi

    2013-01-01

    There is little detailed information on stranded fin whales (Balaenoptera physalus) in the scientific literature (Notarbartolo di Sciara et al., 2003). In Denmark, at least eight fin whales stranded between the years 1603 and 1958 (Kinze, 1995). On 16 June 2010, a live subadult or adult male fin whale stranded in the Bay of Vejle (55º 69' N, 9º 58' E), Denmark. Despite several attempts, it was not possible to rescue the fin whale, which was only partially exposed by the water. The fin whale succumbed after 5 d stranded in shallow water. The dead fin whale was transported to a nearby pier, and a necropsy was performed by a multidisciplinary team, including biologists, conservationists, physicians, and veterinarians representing three universities and several museums.

  17. Photon counting performance measurements of transfer electron InGaAsP photocathode hybrid photomultiplier tubes at 1064 nm wavelength

    Science.gov (United States)

    Sun, Xiaoli; Krainak, Michael A.; Hasselbrack, William B.; La Rue, Ross A.

    2007-05-01

    We report the test results of a hybrid photomultiplier tube (HPMT) with a transfer electron (TE) InGaAsP photocathode and GaAs Schottky avalanche photodiode (APD) anode. Unlike Geiger mode InGaAsP APDs, these HPMTs (also known as intensified photodiode (IPD), vacuum APD, or hybrid photodetector) operate in linear mode without the need for quenching and gating. Their greatest advantages are wide dynamic range, high speed, large photosensitive area, and potential for photon counting and analog detection dual mode operation. The photon detection efficiency we measured was 25% at 1064 nm wavelength with a dark count rate of 60,000/s at -22 degrees Celsius. The output pulse width in response to a single photon detection is about 0.9 ns. The maximum count rate was 90 Mcts/s and was limited solely by the speed of the discriminator used in the measurement (10 ns dead time). The spectral response of these devices extended from 900 to 1300 nm. We also measured the HPMT response to 60 ps laser pulses. The average output pulse amplitude increased monotonically with the input pulse energy, which suggested that we can resolve photon number in an incident pulse. The jitter of the HPMT output was found to be about 0.5 ns standard deviation and depended on bias voltage applied to the TE photocathode. To our knowledge, these HPMTs are the most sensitive non gating photon detectors at 1064 nm wavelength, and they will have many applications in laser altimeters, atmospheric lidars, and free space laser communication systems.

  18. Electron tube

    Science.gov (United States)

    Suyama, Motohiro (Hamamatsu, JP); Fukasawa, Atsuhito (Hamamatsu, JP); Arisaka, Katsushi (Los Angeles, CA); Wang, Hanguo (North Hills, CA)

    2011-12-20

    An electron tube of the present invention includes: a vacuum vessel including a face plate portion made of synthetic silica and having a surface on which a photoelectric surface is provided, a stem portion arranged facing the photoelectric surface and made of synthetic silica, and a side tube portion having one end connected to the face plate portion and the other end connected to the stem portion and made of synthetic silica; a projection portion arranged in the vacuum vessel, extending from the stem portion toward the photoelectric surface, and made of synthetic silica; and an electron detector arranged on the projection portion, for detecting electrons from the photoelectric surface, and made of silicon.

  19. Neutron tubes

    Science.gov (United States)

    Leung, Ka-Ngo (Hercules, CA); Lou, Tak Pui (Berkeley, CA); Reijonen, Jani (Oakland, CA)

    2008-03-11

    A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

  20. Three-dimensional Monte Carlo simulation of bulk fin field effect transistor

    International Nuclear Information System (INIS)

    In this paper, we investigate the performance of the bulk fin field effect transistor (FinFET) through a three-dimensional (3D) full band Monte Carlo simulator with quantum correction. Several scattering mechanisms, such as the acoustic and optical phonon scattering, the ionized impurity scattering, the impact ionization scattering and the surface roughness scattering are considered in our simulator. The effects of the substrate bias and the surface roughness scattering near the Si/SiO2 interface on the performance of bulk FinFET are mainly discussed in our work. Our results show that the on-current of bulk FinFET is sensitive to the surface roughness and that we can reduce the substrate leakage current by modulating the substrate bias voltage

  1. When to change a tracheostomy tube.

    Science.gov (United States)

    White, Alexander C; Kher, Sucharita; O'Connor, Heidi H

    2010-08-01

    Knowing when to change a tracheostomy tube is important for optimal management of all patients with tracheostomy tubes. The first tracheostomy tube change, performed 1-2 weeks after placement, carries some risk and should be performed by a skilled operator in a safe environment. The risk associated with changing the tracheostomy tube then usually diminishes over time as the tracheo-cutaneous tract matures. A malpositioned tube can be a source of patient distress and patient-ventilator asynchrony, and is important to recognize and correct. Airway endoscopy can be helpful to ensure optimal positioning of a replacement tracheostomy tube. Some of the specialized tracheostomy tubes available on the market are discussed. There are few data available to guide the timing of routine tracheostomy tube changes. Some guidelines are suggested. PMID:20667154

  2. Experimental Analysis Of Heat Transfer From Square Perforated Fins In Staggered Arrangement

    Directory of Open Access Journals (Sweden)

    Siddiqui. M. Abdullah

    2015-08-01

    Full Text Available This project gives the experimental analysis of heat transfer over a flat surface equipped with Square perforated pin fins in staggered arrangement in a rectangular channel. The Fin dimensions are 100mm in height & 25mm in width. The range of Reynolds number is fixed & about 13,500– 42,000, the clearance ratio (C/H 0, 0.33 and 1, the inter-fin spacing ratio (Sy /D 1.208, 1.524, 1.944 and 3.417. Sy i.e. stream wise distance is varies and Sx i.e. span wise distance is constant. The friction factor, enhancement efficiency and heat transfer correlate in equations with each other. Here we are comparing Square pin fins with cylindrical pin fins. Staggered arrangement and perforation will enhance the heat transfer rate. Clearance ratio and inter-fin spacing ratio affect on Enhancement efficiency. Both lower clearance ratio and lower inter-fin spacing ratio and comparatively lower Reynolds number give higher thermal performance. Friction factor & Nusselt number are Key parameter which relates with efficiency enhancement and heat transfer rate.

  3. Design, Implementation and Control of a Fish Robot with Undulating Fins

    Directory of Open Access Journals (Sweden)

    Mohsen Siahmansouri

    2011-11-01

    Full Text Available Biomimetic robots can potentially perform better than conventional robots in underwater vehicle designing. This paper describes the design of the propulsion system and depth control of a robotic fish. In this study, inspired by knife fish, we have designed and implemented an undulating fin to produce propulsive force. This undulating fin is a segmental anal fin that produces sinusoidal wave to propel the robot. The relationship between the individual fin segment and phase angles with the overall fin trajectory has also been discussed. This propulsive force can be adjusted and directed for fish robot manoeuvre by a mechanical system with two servomotors. These servomotors regulate the direction and depth of swimming. A wireless remote control system is designed to adjust the servomotors which enables us to control revolution, speed and phase differences of neighbor servomotors of fins. Finally, Field trials are conducted in an outdoor pool to demonstrate the relationship between robotic fish speed and fin parameters like phase difference, the number of phase and undulatory amplitude.

  4. Fish's Muscles Distortion and Pectoral Fins Propulsion of Lift-Based Mode

    Science.gov (United States)

    Yang, S. B.; Han, X. Y.; Qiu, J.

    As a sort of MPF(median and/or paired fin propulsion), pectoral fins propulsion makes fish easier to maneuver than other propulsion, according to the well-established classification scheme proposed by Webb in 1984. Pectoral fins propulsion is classified into oscillatory propulsion, undulatory propulsion and compound propulsion. Pectoral fins oscillatory propulsion, is further ascribable to two modes: drag-based mode and lift-based mode. And fish exhibits strong cruise ability by using lift-based mode. Therefore to robot fish design using pectoral fins lift-based mode will bring a new revolution to resources exploration in blue sea. On the basis of the wave plate theory, a kinematic model of fish’s pectoral fins lift-based mode is established associated with the behaviors of cownose ray (Rhinoptera bonasus) in the present work. In view of the power of fish’s locomotion from muscle distortion, it would be helpful benefit to reveal the mechanism of fish’s locomotion variation dependent on muscles distortion. So this study puts forward the pattern of muscles distortion of pectoral fins according to the character of skeletons and muscles of cownose ray in morphology and simulates the kinematics of lift-based mode using nonlinear analysis software. In the symmetrical fluid field, the model is simulated left-right symmetrically or asymmetrically. The results qualitatively show how muscles distortion determines the performance of fish locomotion. Finally the efficient muscles distortion associated with the preliminary dynamics is induced.

  5. Heat transfer and pressure drop characteristics of mini-fin structures

    International Nuclear Information System (INIS)

    Forced convection heat transfer of air and water in bronze and pure copper mini-fin structures and mini-channel structures was investigated experimentally. The mini-fin dimensions were 0.7 mm x 0.2 mm and 0.8 mm x 0.4 mm. The tests included both staggered diamond-shaped and in-line square mini-fin arrangements. The tests investigated the effects of structures, mini-fin dimensions and arrangement, test section materials, and fluid properties on the convection heat transfer and heat transfer enhancement. For the tested conditions, the convection heat transfer coefficient was increased 9-21 fold for water and 12-38 fold for air in the mini-fin structures compared with an empty plate channel. The friction factor and flow resistance in the mini-channel structures and the in-line square mini-fin arrangement were much less than in the staggered diamond-shaped mini-fin arrangement. For the small channel width, Wc = 0.2 mm, the convection heat transfer with the in-line square array structure was more intense than with the staggered diamond-shaped structure, the mini-channel structure or the porous media. For the larger channel width, Wc = 0.4 mm, the convection heat transfer in the staggered diamond-shaped array structure was more intense than in the others systems while the in-line square structure had the best overall thermal-hydraulic performance

  6. Out-of-plane strain effect on silicon-based flexible FinFETs

    KAUST Repository

    Ghoneim, Mohamed T.

    2015-06-21

    Summary form only given. We report out-of-plane strain effect on silicon based flexible FinFET, with sub 20 nm wide fins and hafnium silicate based high-? gate dielectric. Since ultra-thin inorganic solid state substrates become flexible with reduced thickness, flexing induced strain does not enhance performance. However, detrimental effects arise as the devices are subject to various out-of-plane stresses (compressive and tensile) along the channel length.

  7. Diversification of the pectoral fin shape in damselfishes (Perciformes, Pomacentridae) of the Eastern Pacific

    OpenAIRE

    Aguilar-Medrano, Rosalia; Frederich, Bruno; Balart, Eduardo F; De Luna, Efrain

    2013-01-01

    Fin shape strongly influences performance of locomotion across all swimming styles. In this study, we focused on the diversity of the pectoral fin morphology in damselfishes of the Eastern Pacific. Underwater observations and a review of literature allowed the characterization of ten behavioral groups. Territorial and non-territorial species were discriminated easily with traditional morphometrics. Five ecomorphological groups were recognized by geometric morphometric analyses. Geometric data...

  8. Negative effect of smoking on the performance of the QuantiFERON TB gold in tube test

    OpenAIRE

    Aabye Martine G; Hermansen Thomas Stig; Ruhwald Morten; PrayGod George; Faurholt-Jepsen Daniel; Jeremiah Kidola; Faurholt-Jepsen Maria; Range Nyagosya; Friis Henrik; Changalucha John; Andersen Aase B; Ravn Pernille

    2012-01-01

    Abstract Background False negative and indeterminate Interferon Gamma Release Assay (IGRA) results are a well documented problem. Cigarette smoking is known to increase the risk of tuberculosis (TB) and to impair Interferon-gamma (IFN-?) responses to antigenic challenge, but the impact of smoking on IGRA performance is not known. The aim of this study was to evaluate the effect of smoking on IGRA performance in TB patients in a low and high TB prevalence setting respectively. Methods Patients...

  9. Negative effect of smoking on the performance of the QuantiFERON TB gold in tube test

    DEFF Research Database (Denmark)

    Aabye, Martine G; Hermansen, Thomas Stig; Ruhwald, Morten; Praygod, George Amani; Faurholt-Jepsen, Daniel; Kidola, Jeremiah; Faurholt-Jepsen, Maria; Range, Nyagosya; Friis, Henrik; Changalucha, John; Andersen, Aase B; Ravn, Pernille

    2012-01-01

    ABSTRACT: BACKGROUND: False negative and indeterminate Interferon Gamma Release Assay (IGRA) results are a well documented problem. Cigarette smoking is known to increase the risk of tuberculosis (TB) and to impair Interferon-gamma (IFN-gamma) responses to antigenic challenge, but the impact of smoking on IGRA performance is not known. The aim of this study was to evaluate the effect of smoking on IGRA performance in TB patients in a low and high TB prevalence setting respectively. METHODS: Pati...

  10. Whole shaft visibility and mechanical performance for active MR catheters using copper-nitinol braided polymer tubes

    OpenAIRE

    McVeigh Elliot R; Ozturk Cengizhan; Ratnayaka Kanishka; Faranesh Anthony Z; Guttman Michael A; Saikus Christina E; Kocaturk Ozgur; Lederman Robert J

    2009-01-01

    Abstract Background Catheter visualization and tracking remains a challenge in interventional MR. Active guidewires can be made conspicuous in "profile" along their whole shaft exploiting metallic core wire and hypotube components that are intrinsic to their mechanical performance. Polymer-based catheters, on the other hand, offer no conductive medium to carry radio frequency waves. We developed a new "active" catheter design for interventional MR with mechanical performance resembling braide...

  11. Pressure tube procurement for CANDU reactors

    International Nuclear Information System (INIS)

    The procurement practice on pressure tubes for CANDU reactors is described. The reference design, the metallurgical and the quality assurance requirements relating to the procurement actions are noted. The objectives of procurement engineering are related to improving the tube quality and performance by specific changes in the pressure tube fabrication and the qualification procedure governing changes is briefly outlined. The future direction of pressure tube procurement practice is discussed

  12. Design of spiral fin type condenser for hydrogen cryogenic distillation column

    International Nuclear Information System (INIS)

    The purpose of this paper is the proposal of new concept condenser for hydrogen cryogenic distillation column of Hydrogen Isotope Separation System (ISS) in a fusion reactor, and the establishment of numerical evaluation method of the hydrogen isotope inventory in the condenser. A large amount of hydrogen isotopes including high concentration of tritium, radioactive hydrogen isotope, has been handled in the cryogenic distillation column. Therefore, from the safety point of view, cryogenic coolant tube was commonly arranged to surround the condensed area to prevent the mixing of tritium into the coolant. This inevitable arrangement leads the difficulty in the minimization of the condenser. The scale of condenser has influence on the scale of the ISS and its earthquake-resistance. The spiral fin type condenser, which introduces fins inside it and in coolant tube to enhance heat exchange, is proposed as a new concept condenser for hydrogen cryogenic distillation column to miniaturize the condenser. The volume of spiral fin type condenser is estimated to become less than half of that of coil tube type condenser currently in use. Accordingly, it is found that the adoption of spiral fin type condenser realizes the significant miniaturization of the ISS. Moreover, the numerical evaluation method of the hydrogen isotope inventory in the condenser is proposed. The validity of this method was confirmed by the experimental data. The synthetic design of the condenser for the hydrogen cryogenic distillation column is achieved by the combination of the proposed new concept condenser with the numerical evaluation method of the hydrogen isotope inventory. (author)

  13. Optimization of fin-swim training for SCUBA divers.

    Science.gov (United States)

    Wylegala, J; Schafer-Owczarzak, M; Pendergast, D R

    2007-01-01

    Underwater swimming is a unique exercise and its fitness is not accomplished by other types of training. This study compared high intensity intermittent fin-swim training (HIIT) with moderate intensity continuous (MICT). Divers (n = 20; age = 23 +/- 4 yrs; weight = 82.57 +/- 10.38 kg; height = 180 +/- 6 cm) were assigned to MICT (65%-75% heart rate max (HRmax), for 45 min) or HIIT three 10 min swims/rest cycles (77%, 83%, and 92% HRmax, respectively) for 50 min. They trained using snorkel and fins at the surface paced by an underwater light system 3 times per week for 4 weeks. Swim tests were the energy cost of swimming, VO2max and timed endurance swim (at 70%/VO2max). The VO2 was a non-significantly reduced at any velocity with either HIIT or MICT. Maximal swim velocity increased after HIIT (10%) (p 0.05). VO2max increased 18% after HIIT and 6% after MICT (p swim lactate was not significantly different and averaged 4.69 +/- 1.10mM (p > 0.05). Although both training methods significantly improved fin swimming performance with similar time commitments, the HIIT improved VO2max and endurance more than MICT (p swim fitness. PMID:18251440

  14. Performance improvement of small gamma camera using NaI(Tl) plate and position sensitive photo-multiplier tubes

    International Nuclear Information System (INIS)

    The purpose of this study was to improve the performance of a small gamma camera, utilizing a NaI(Tl) plate and a 5'' position sensitive PMT. We attempted to build a NaI(Tl) plate crystal system which retained all its advantages, while at the same time integrating some of the advantages inherent in an array-type scintillation crystal system. Flood images were obtained with a lead hole mask, and position mapping was performed by detecting hole positions in the flood image. Energy calibration was performed using the energy spectra obtained from each hole position. Flood correction was performed using a uniformity correction table containing the relative efficiency of each image element. The spatial resolution was improved about 16% after correction at the centre field of view. Resolution deterioration at the outer field of view (OFOV) was considerably ameliorated, from 6.7 mm to 3.2 mm after correction. The sensitivity at the OFOV was also increased after correction, from 0.7 cps ?Ci-1 to 2.0 cps ?Ci-1. The correction also improved uniformity, from 5.2% to 2.1%, and linearity, from 0.5 mm to 0 mm. The results of this study indicate that the revised correction method can be employed to considerably improve the performance of a small gamma camera using a NaI(Tl) plate-type crystal. This method also provides high spatial resolution and linearity, like array-type crystals do, while retaining the specific advantages of plate-type crystals

  15. photomultiplier tubes

    CERN Multimedia

    photomultiplier tubes. A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  16. photomultiplier tube

    CERN Multimedia

    photomultiplier tubes. A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  17. Blue shark Prionace glauca fin-to-carcass-mass ratios in Spain and implications for finning ban enforcement.

    Science.gov (United States)

    Santana-Garcon, J; Fordham, S; Fowler, S

    2012-04-01

    This study examines the processing of fins from blue sharks Prionace glauca caught by the Spanish longline fleet and landed in Vigo, Spain, and implications of these practices for enforcing the E.U. ban on shark finning, which relies on a maximum fin-to-carcass-mass ratio. Two major sources of variability in fin-to-carcass ratios are quantified and discussed: (1) the fin set (type and number of fins retained from each shark) and (2) the cutting method used to separate fins from carcasses. The significant differences in fin-to-carcass-mass ratios between fin sets or cutting procedure demonstrates that the ratio limit is problematic and, conclusively, in order to facilitate proper enforcement, fishermen should be required to land all sharks with the fins still naturally attached to the bodies. PMID:22497411

  18. Thermoelectric generator with hinged assembly for fins

    International Nuclear Information System (INIS)

    A cylindrical casing has a central shielded capsule of radioisotope fuel. A plurality of thermonuclear modules are axially arranged with their hot junctions resiliently pressed toward the shield and with their cold junctions adjacent a transition member having fins radiating heat to the environment. For each module, the assembly of transition member and fins is hinged to the casing for swinging to permit access to and removal of such module. A ceramic plate having gold layers on opposite faces prevents diffusion bonding of the hot junction to the shield

  19. Whole shaft visibility and mechanical performance for active MR catheters using copper-nitinol braided polymer tubes

    Directory of Open Access Journals (Sweden)

    McVeigh Elliot R

    2009-08-01

    Full Text Available Abstract Background Catheter visualization and tracking remains a challenge in interventional MR. Active guidewires can be made conspicuous in "profile" along their whole shaft exploiting metallic core wire and hypotube components that are intrinsic to their mechanical performance. Polymer-based catheters, on the other hand, offer no conductive medium to carry radio frequency waves. We developed a new "active" catheter design for interventional MR with mechanical performance resembling braided X-ray devices. Our 75 cm long hybrid catheter shaft incorporates a wire lattice in a polymer matrix, and contains three distal loop coils in a flexible and torquable 7Fr device. We explored the impact of braid material designs on radiofrequency and mechanical performance. Results The incorporation of copper wire into in a superelastic nitinol braided loopless antenna allowed good visualization of the whole shaft (70 cm in vitro and in vivo in swine during real-time MR with 1.5 T scanner. Additional distal tip coils enhanced tip visibility. Increasing the copper:nitinol ratio in braiding configurations improved flexibility at the expense of torquability. We found a 16-wire braid of 1:1 copper:nitinol to have the optimum balance of mechanical (trackability, flexibility, torquability and antenna (signal attenuation properties. With this configuration, the temperature increase remained less than 2°C during real-time MR within 10 cm horizontal from the isocenter. The design was conspicuous in vitro and in vivo. Conclusion We have engineered a new loopless antenna configuration that imparts interventional MR catheters with satisfactory mechanical and imaging characteristics. This compact loopless antenna design can be generalized to visualize the whole shaft of any general-purpose polymer catheter to perform safe interventional procedures.

  20. Performance characterization of high quantum efficiency metal package photomultiplier tubes for time-of-flight and high-resolution PET applications

    International Nuclear Information System (INIS)

    Purpose: Metal package photomultiplier tubes (PMTs) with a metal channel dynode structure have several advanced features for devising such time-of-flight (TOF) and high spatial resolution positron emission tomography (PET) detectors, thanks to their high packing density, large effective area ratio, fast time response, and position encoding capability. Here, we report on an investigation of new metal package PMTs with high quantum efficiency (QE) for high-resolution PET and TOF PET detector modules. Methods: The latest metal package PMT, the Hamamatsu R11265 series, is served with two kinds of photocathodes that have higher quantum efficiency than normal bialkali (typical QE ? 25%), super bialkali (SBA; QE ? 35%), and ultra bialkali (UBA; QE ? 43%). In this study, the authors evaluated the performance of the new PMTs with SBA and UBA photocathodes as a PET detector by coupling various crystal arrays. They also investigated the performance improvements of high QE, focusing in particular on a block detector coupled with a lutetium-based scintillator. A single 4 × 4 × 10 mm3 LYSO, a 7 × 7 array of 3 × 3 × 20 mm3 LGSO, a 9 × 9 array of 1.2 × 1.2 × 10 mm3 LYSO, and a 6 × 6 array of 1.5 × 1.5 × 7 mm3 LuYAP were used for evaluation. All coincidence data were acquired with a DRS4 based fast digitizer. Results: This new PMT shows promising crystal positioning accuracy, energy and time discrimination performance for TOF, and high-resolution PET applications. The authors also found that a metal channel PMT with SBA was enough for both TOF and high-resolution application, although UBA gave a minor improvement to time resolution. However, significant performance improvement was observed in relative low light output crystals (LuYAP) coupled with UBA. Conclusions: The results of this study will be of value as a useful reference to select PMTs for high-performance PET detectors

  1. Artificial Neural Network Modelling of the Thermal Performance of a Compact Heat Exchanger

    OpenAIRE

    Tan, C.K.; Ward, J; Wilcox, S.J.; Payne, R.

    2009-01-01

    Abstract This paper reports the use of artificial neural network models to simulate the thermal performance of a compact, fin-tube heat exchanger with air and water/ethylene glycol anti-freeze mixtures as the working fluids. The model predictions were compared with experimental data over a range of flow rates and inlet temperatures and with various ethylene glycol concentrations. In addition, the inlet air flow was distorted by obstructing part of the inlet ducting near the front f...

  2. The use of hand paddles and fins in front crawl: biomechanical and physiological responses

    Directory of Open Access Journals (Sweden)

    Cristiano Cardoso de Matos

    2013-04-01

    Full Text Available Paddles and fins are used during swim training and practice as tools for improving performance. The use of these equipment can alter physiological and kinematic parameters of swimming. The purpose of this literature review was to present and discussthe effects of paddles and fins on kinematic and physiological variables in front crawl,and provide update on the topic for teachers, researchers, coaches and swimmers. Thirty articles were reviewed. To crawl, paddles can change the averages of stroke length and stroke rate, the average swimming speed, the absolute duration of the stroke phases and the index of coordination. Fins can modify the average stroke rate, the average swimming speed, the kick frequency and deep, and the energy cost. We found no studies that verified the longitudinal effects of the use of paddles and fins on these parameters.

  3. Influence of Pr on Natural Convection Heat Transfer of an Open Channel Finned Plate

    International Nuclear Information System (INIS)

    The finned plate provides the extended heat transfer area and improves the heat transfer. However when the fin spacing becomes small, the pressure drop increases due to frictional loss, heat transfer is impaired. Thus there is an optimal fin spacing. For the natural convection heat transfer, the heated thermal boundary layer drives the flow and the influence of the Prandtl number on the heat transfer will be very important as the thickness of the thermal boundary layer depends on it. This study aims at investigating the influence of the Prandtl number on the natural convection heat transfer of the finned plate. Numerical analyses were performed by varying the Pr from 2 to 2,014. Numerical analysis was performed for the natural convection heat transfer of a finned plate in an open channel. In order to investigate the influence of the Prandtl number on the heat transfer, four different values of Prandtl numbers were simulated and compared. As expected, the velocity profiles were almost similar except for the fact that the boundary layer develops earlier for smaller Prandtl number fluid. However the temperature profiles varied drastically depending on the values of the Prandtl number. As the Prandtl number increases, the thermal boundary layer reduces. The comparisons of the results with Le Fevre natural convection heat transfer correlation for vertical plate shows that as the Pr increases, the NuL of the finned plate becomes similar to that of the flat plate of the same heat transfer area

  4. Exotic wakes of flapping fins

    DEFF Research Database (Denmark)

    Schnipper, Teis

    2011-01-01

    We present, in 8 chapters, experiments on and numerical simulations of bodies flapping in a fluid. Focus is predominantly on a rigid foil, a model fish, that performs prescribed pitching oscillations where the foil rotates around its leading edge. In a flowing soap film is measured, with unprecedented accuracy, the vortex wake structure behind the flapping foil in the space spanned by dimensionless flapping frequency 0

  5. X-ray tubes

    International Nuclear Information System (INIS)

    An improved form of x-ray tube is described which consists of a rotatable anode disc and an electron beam source enclosed in an envelope. The beam of electrons strikes the edge of the anode disc at an acute angle, producing x-rays which are transmitted through a window in the envelope. To improve performance and life of the anode disc it is additionally reciprocated back and forth along its axis of rotation. Dimensions are specified. (U.K.)

  6. Temperature-time distribution and thermal stresses on the RTG fins and shell during water cooling

    Science.gov (United States)

    Turner, R. H.

    1983-01-01

    Radioisotope thermoelectric generator (RTG) packages designed for space missions generally do not require active cooling. However, the heat they generate cannot remain inside of the launch vehicle bay and requires active removal. Therefore, before the Shuttle bay door is closed, the RTG coolant tubes attached to the heat rejection fins must be filled with water, which will circulate and remove most of the heat from the cargo bay. There is concern that charging a system at initial temperature around 200 C with water at 24 C can cause unacceptable thermal stresses in the RTG shell and fins. A computer model is developed to estimate the transient temperature distribution resulting from such charging. The thermal stresses resulting from the temperature gradients do not exceed the elastic deformation limit for the material. Since the simplified mathematical model for thermal stresses tends to overestimate stresses, it is concluded that the RTG can be cooled by introducing water at 24 C to the initially hot fin coolant tubes while the RTG is in the Shuttle cargo bay.

  7. Experimental investigation of vortex-fin interaction

    Science.gov (United States)

    Washburn, Anthony E.; Jenkins, Luther N.; Ferman, Marty A.

    1993-01-01

    An experimental investigation has been conducted to examine the mechanisms of vortex-fin interaction on a twin-fin configuration. The investigation included a parametric study of the effect of tail location. The vortices were generated by a 76 deg sharp-edged delta wing with vertical tails mounted behind the wing. The model included both a dynamically-scaled flexible tail and a pressure instrumented rigid tail. Surface oil-flow patterns, off-body laser light sheet visualizations, aerodynamic load measurements, mean and unsteady flexible tail response, and unsteady tail surface pressure measurements were obtained. The results show that the tail location did not affect the upstream trajectory of the delta wing vortex. The tail location did affect the location of vortex breakdown, the global structure of the flow field, the aerodynamic loads, and the fin buffeting levels. The buffeting levels were reduced as the fins were moved laterally toward the vortex core trajectory. Two distinct peaks were observed in the pressure excitation spectra in the post-breakdown flow. Finally, the presence of the flexible tail opposite the rigid pressure tail altered the pressure measurements at one angle of attack.

  8. Numerical study of finned heat pipe-assisted thermal energy storage system with high temperature phase change material

    International Nuclear Information System (INIS)

    Highlights: • A finned heat pipe-assisted latent heat thermal energy storage system is studied. • The effects of heat pipes spacing and fins geometrical features are investigated. • Smaller heat pipes spacing and longer fins improve the melting rate. • The optimal heat pipe and fin arrangements are determined. - Abstract: In the present study, the thermal characteristics of a finned heat pipe-assisted latent heat thermal energy storage system are investigated numerically. A transient two-dimensional finite volume based model employing enthalpy-porosity technique is implemented to analyze the performance of a thermal energy storage unit with square container and high melting temperature phase change material. The effects of heat pipe spacing, fin length and numbers and the influence of natural convection on the thermal response of the thermal energy storage unit have been studied. The obtained results reveal that the natural convection has considerable effect on the melting process of the phase change material. Increasing the number of heat pipes (decreasing the heat pipe spacing) leads to the increase of melting rate and the decrease of base wall temperature. Also, the increase of fin length results in the decrease of temperature difference within the phase change material in the container, providing more uniform temperature distribution. It was also shown that number of the fins does not have a significant effect on the performance of the system

  9. Liquid-metal pin-fin pressure drop by correlation in cross flow

    International Nuclear Information System (INIS)

    The pin-fin configuration is widely used as a heat transfer enhancement method in high-heat-flux applications. Recently, the pin-fin design with liquid-metal coolant was also applied to synchrotron-radiation beamline devices. This paper investigates the pressure drop in a pin-post design beamline mirror with liquid gallium as the coolant. Because the pin-post configuration is a relatively new concept, information in literature about pin-post mirrors or crystals is rare, and information about the pressure drop in pin-post mirrors with liquid metal as the coolant is even more sparse. Due to this the authors considered the cross flow in cylinder-array geometry, which is very similar to that of the pin-post, to examine the pressure drop correlation with liquid metals over pin fins. The cross flow of fluid with various fluid characteristics or properties through a tube bank was studied so that the results can be scaled to the pin-fin geometry with liquid metal as the coolant. Study lead to two major variables to influence the pressure drop: fluid properties, viscosity and density, and the relative length of the posts. Correlation of the pressure drop between long and short posts and the prediction of the pressure drop of liquid metal in the pin-post mirror and comparison with an existing experiment are addressed

  10. Fin width and height dependence of bipolar amplification in bulk FinFETs submitted to heavy ion irradiation

    Science.gov (United States)

    Yu, Jun-Ting; Chen, Shu-Ming; Chen, Jian-Jun; Huang, Peng-Cheng

    2015-11-01

    FinFET technologies are becoming the mainstream process as technology scales down. Based on a 28-nm bulk p-FinFET device, we have investigated the fin width and height dependence of bipolar amplification for heavy-ion-irradiated FinFETs by 3D TCAD numerical simulation. Simulation results show that due to a well bipolar conduction mechanism rather than a channel (fin) conduction path, the transistors with narrower fins exhibit a diminished bipolar amplification effect, while the fin height presents a trivial effect on the bipolar amplification and charge collection. The results also indicate that the single event transient (SET) pulse width can be mitigated about 35% at least by optimizing the ratio of fin width and height, which can provide guidance for radiation-hardened applications in bulk FinFET technology. Project supported by the National Natural Science of China (Grant No. 61376109).

  11. Investigation of negative bias temperature instability dependence on fin width of silicon-on-insulator-fin-based field effect transistors

    Science.gov (United States)

    Young, Chadwin D.; Neugroschel, Arnost; Majumdar, Kausik; Matthews, Ken; Wang, Zhe; Hobbs, Chris

    2015-01-01

    The fin width dependence of negative bias temperature instability (NBTI) of double-gate, fin-based p-type Field Effect Transistors (FinFETs) fabricated on silicon-on-insulator (SOI) wafers was investigated. The NBTI degradation increased as the fin width narrowed. To investigate this phenomenon, simulations of pre-stress conditions were employed to determine any differences in gate oxide field, fin band bending, and electric field profile as a function of the fin width. The simulation results were similar at a given gate stress bias, regardless of the fin width, although the threshold voltage was found to increase with decreasing fin width. Thus, the NBTI fin width dependence could not be explained from the pre-stress conditions. Different physics-based degradation models were evaluated using specific fin-based device structures with different biasing schemes to ascertain an appropriate model that best explains the measured NBTI dependence. A plausible cause is an accumulation of electrons that tunnel from the gate during stress into the floating SOI fin body. As the fin narrows, the sidewall device channel moves in closer proximity to the stored electrons, thereby inducing more band bending at the fin/dielectric interface, resulting in a higher electric field and hole concentration in this region during stress, which leads to more degradation. The data obtained in this work provide direct experimental proof of the effect of electron accumulation on the threshold voltage stability in FinFETs.

  12. Investigation of negative bias temperature instability dependence on fin width of silicon-on-insulator-fin-based field effect transistors

    International Nuclear Information System (INIS)

    The fin width dependence of negative bias temperature instability (NBTI) of double-gate, fin-based p-type Field Effect Transistors (FinFETs) fabricated on silicon-on-insulator (SOI) wafers was investigated. The NBTI degradation increased as the fin width narrowed. To investigate this phenomenon, simulations of pre-stress conditions were employed to determine any differences in gate oxide field, fin band bending, and electric field profile as a function of the fin width. The simulation results were similar at a given gate stress bias, regardless of the fin width, although the threshold voltage was found to increase with decreasing fin width. Thus, the NBTI fin width dependence could not be explained from the pre-stress conditions. Different physics-based degradation models were evaluated using specific fin-based device structures with different biasing schemes to ascertain an appropriate model that best explains the measured NBTI dependence. A plausible cause is an accumulation of electrons that tunnel from the gate during stress into the floating SOI fin body. As the fin narrows, the sidewall device channel moves in closer proximity to the stored electrons, thereby inducing more band bending at the fin/dielectric interface, resulting in a higher electric field and hole concentration in this region during stress, which leads to more degradation. The data obtained in this work provide direct experimental proof of the effect of electron accumulation on the threshold voltage stability in FinFETs

  13. Exotic wakes of flapping fins

    DEFF Research Database (Denmark)

    Schnipper, Teis

    2011-01-01

    We present, in 8 chapters, experiments on and numerical simulations of bodies flapping in a fluid. Focus is predominantly on a rigid foil, a model fish, that performs prescribed pitching oscillations where the foil rotates around its leading edge. In a flowing soap film is measured, with unprecedented accuracy, the vortex wake structure behind the flapping foil in the space spanned by dimensionless flapping frequency 0

  14. Experimental studies on heat and mass transfer performance of a coiled tube absorber for R134a-DMAC based absorption cooling system

    Science.gov (United States)

    Mohideen, S. Tharves; Renganarayanan, S.

    2008-04-01

    Absorber is an important component in vapor absorption refrigeration system and its performance has greater influence in overall efficiency of absorption machines. Falling film heat and mass transfer in an absorber is greatly influenced by fluid properties, geometry of heat exchanger and its operating parameters. This paper presents on the results of experimental studies on the heat and mass transfer characteristics of a coiled tube falling film absorber, using 1,1,1,2-Tetrafluroethane(R-134a) and N-N Dimethyl Acetamide (DMAC) as working fluids. The effects of film Reynolds number, inlet solution temperature and cooling water temperature on absorber heat load, over all heat transfer coefficient and mass of refrigerant absorbed are presented and discussed. Normalized solution and coolant temperature profiles and refrigerant mass absorbed along the height of absorber are also observed from the experimental results. The optimum over all heat transfer coefficient for R-134a DMAC solution found to be 726 W/m2K for a film Reynolds number of 350. The R-134a vapour absorption rate is maximum in the normalized coil height of 0.6 to 1.

  15. Experimental studies on heat and mass transfer performance of a coiled tube absorber for R134a-DMAC based absorption cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Mohideen, S.T. [Institute of Road and Transport Technology, Erode, Tamil Nadu (India); Renganarayanan, S. [Institute for Energy Studies, Anna University, Chennai, Tamil Nadu (India)

    2008-11-15

    Absorber is an important component in vapor absorption refrigeration system and its performance has greater influence in overall efficiency of absorption machines. Falling film heat and mass transfer in an absorber is greatly influenced by fluid properties, geometry of heat exchanger and its operating parameters. This paper presents on the results of experimental studies on the heat and mass transfer characteristics of a coiled tube falling film absorber, using 1,1,1,2-Tetrafluroethane(R-134a) and N-N Dimethyl Acetamide (DMAC) as working fluids. The effects of film Reynolds number, inlet solution temperature and cooling water temperature on absorber heat load, over all heat transfer coefficient and mass of refrigerant absorbed are presented and discussed. Normalized solution and coolant temperature profiles and refrigerant mass absorbed along the height of absorber are also observed from the experimental results. The optimum over all heat transfer coefficient for R-134a-DMAC solution found to be 726 W/m{sup 2}K for a film Reynolds number of 350. The R-134a vapour absorption rate is maximum in the normalized coil height of 0.6 to 1. (orig.)

  16. Effect of tube depth on the photovoltaic performance of CdS quantum dots sensitized ZnO nanotubes solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lili [Institute of Condensed State Physics, Jilin Normal University, Siping 136000, People' s Republic of China (China); Institute of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, People' s Republic of China (China); Key Laboratory of Functional Materials Physics and Chemistry (Jilin Normal University), Ministry of Education, Siping 136000, People' s Republic of China (China); Zhang, Zhiqiang [Institute of Condensed State Physics, Jilin Normal University, Siping 136000, People' s Republic of China (China); Key Laboratory of Functional Materials Physics and Chemistry (Jilin Normal University), Ministry of Education, Siping 136000, People' s Republic of China (China); Yang, Jinghai, E-mail: jhyang1@jlnu.edu.cn [Institute of Condensed State Physics, Jilin Normal University, Siping 136000, People' s Republic of China (China); Key Laboratory of Functional Materials Physics and Chemistry (Jilin Normal University), Ministry of Education, Siping 136000, People' s Republic of China (China); Yan, Yongsheng [Institute of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, People' s Republic of China (China); Sun, Yunfei [Key Laboratory of Excited State Physics, Changchun Institute of Optics Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, People' s Republic of China (China); Cao, Jian; Gao, Ming [Institute of Condensed State Physics, Jilin Normal University, Siping 136000, People' s Republic of China (China); Key Laboratory of Functional Materials Physics and Chemistry (Jilin Normal University), Ministry of Education, Siping 136000, People' s Republic of China (China); and others

    2012-12-05

    Highlights: Black-Right-Pointing-Pointer ZnO nanotubes as photoanode can enhance the energy conversion efficiency. Black-Right-Pointing-Pointer ZnO nanotubes with larger surface area can load more CdS QDs to absorb more light. Black-Right-Pointing-Pointer ZnO nanotubes can provide two transfer channels for photo-injected carrier. - Abstract: High-density and vertically-aligned ZnO nanotubes (ZNTs) with different depth and ZnO nanorods (ZNRs) were used as photoelectrodes to assemble the CdS quantum dots sensitized solar cells (QDSSCs). In comparison with the CdS sensitized ZNRs solar cell, up to 170% enhancement in energy conversion efficiency was achieved for the CdS sensitized ZNTs under the white light illumination intensity of 100 mW/cm{sup 2}. The investigation about the effects of tube depth on the photovoltaic performance of ZNTs/CdS electrodes revealed that at least two factors induce the enhancement of their conversion efficiency. One is that the higher surface-volume ratio of ZNTs can effectively increase the loading amount of CdS QDs, which can effectively absorb the light. The other is that the outer and inner wall of ZNTs can provide two transfer channels for photo-injected carriers, which can improve the efficiency of current collection.

  17. Embryonic development of fin spines in Callorhinchus milii (Holocephali); implications for chondrichthyan fin spine evolution.

    Science.gov (United States)

    Jerve, Anna; Johanson, Zerina; Ahlberg, Per; Boisvert, Catherine

    2014-01-01

    Fin spines are commonly known from fossil gnathostomes (jawed vertebrates) and are usually associated with paired and unpaired fins. They are less common among extant gnathostomes, being restricted to the median fins of certain chondrichthyans (cartilaginous fish), including chimaerids (elephant sharks) and neoselachians (sharks, skates, and rays). Fin spine growth is of great interest and relevance but few studies have considered their evolution and development. We investigated the development of the fin spine of the chimaerid Callorhinchus milii using stained histological sections from a series of larval, hatchling, and adult individuals. The lamellar trunk dentine of the Callorhinchus spine first condenses within the mesenchyme, rather than at the contact surface between mesenchyme and epithelium, in a manner more comparable to dermal bone formation than to normal odontode development. Trabecular dentine forms a small component of the spine under the keel; it is covered externally with a thin layer of lamellar trunk dentine, which is difficult to distinguish in sectioned adult spines. We suggest that the distinctive characteristics of the trunk dentine may reflect an origin through co-option of developmental processes involved in dermal bone formation. Comparison with extant Squalus and a range of fossil chondrichthyans shows that Callorhinchus is more representative than Squalus of generalized chondrichthyan fin-spine architecture, highlighting its value as a developmental model organism. PMID:25378057

  18. Comparative Experimental Analysis of the Thermal Performance of Evacuated Tube Solar Water Heater Systems With and Without a Mini-Compound Parabolic Concentrating (CPC) Reflector(C < 1)

    OpenAIRE

    Yuehong Su; Gang Pei; Guiqiang Li; Xi Zhou; Jie Ji

    2012-01-01

    Evacuated tube solar water heater systems are widely used in China due to their high thermal efficiency, simple construction requirements, and low manufacturing costs. CPC evacuated tube solar water heaters with a geometrical concentration ratio C of less than one are rare. A comparison of the experimental rig of evacuated tube solar water heater systems with and without a mini-CPC reflector was set up, with a series of experiments done in Hefei (31°53'N, 117°15'E), China. The first and secon...

  19. The impact of process variations on input impedance and mitigation using a circuit technique in FinFET-based LNA

    Science.gov (United States)

    Suresh, D.; Nagarajan, K. K.; Srinivasan, R.

    2015-04-01

    The effect of process variations of a FinFET-based low noise amplifier (LNA) are mitigated by using the device in an independently driven mode, i.e. an independently driven double gate (IDDG) FinFET. A 45 nm gate length IDDG FinFET-based cascoded LNA, operating at 5 GHz, is designed and studied to assess the impact of process variation on the LNA performance metrics such as input impedance, gain and noise figure. Four geometrical parameters, gate length, channel width, gate oxide thickness and fin width, and one non-geometrical parameter, channel doping concentration, are considered in the study. The effect of these variations on the input impedance (the desired value is 50 ? purely real) of the LNA is compensated by the second gate bias of the IDDG FinFET. Project supported by the Defense Research Development Organization (DRDO), Government of India.

  20. Fabrication of AlGaN/GaN ?-shaped nanowire fin-shaped FETs by a top-down approach

    Science.gov (United States)

    Im, Ki-Sik; Sindhuri, Vodapally; Jo, Young-Woo; Son, Dong-Hyeok; Lee, Jae-Hoon; Cristoloveanu, Sorin; Lee, Jung-Hee

    2015-06-01

    An AlGaN/GaN-based ?-shaped nanowire fin-shaped FET (FinFET) with a fin width of 50 nm was fabricated using tetramethylammonium hydroxide (TMAH)-based lateral wet etching. An atomic layer deposited (ALD) HfO2 side-wall layer served as the etching mask. ALD Al2O3 and TiN layers were used as the gate dielectric and gate metal, respectively. The ?-shaped gate structure fully depletes the active fin body and almost completely separates the depleted fin from the underlying thick GaN buffer layer, resulting in superior device performance. The top-down processing proposed in this work provides a viable pathway towards gate-all-around devices for III–nitride semiconductors.