WorldWideScience

Sample records for cooling heat transfer

  1. Gas turbine heat transfer and cooling technology

    CERN Document Server

    Han, Je-Chin; Ekkad, Srinath

    2012-01-01

    FundamentalsNeed for Turbine Blade CoolingTurbine-Cooling TechnologyTurbine Heat Transfer and Cooling IssuesStructure of the BookReview Articles and Book Chapters on Turbine Cooling and Heat TransferNew Information from 2000 to 2010ReferencesTurbine Heat TransferIntroductionTurbine-Stage Heat TransferCascade Vane Heat-Transfer ExperimentsCascade Blade Heat TransferAirfoil Endwall Heat TransferTurbine Rotor Blade Tip Heat TransferLeading-Edge Region Heat TransferFlat-Surface Heat TransferNew Information from 2000 to 20102.10 ClosureReferencesTurbine Film CoolingIntroductionFilm Cooling on Rotat

  2. Heat Transfer Augmentation for Electronic Cooling

    Directory of Open Access Journals (Sweden)

    Suabsakul Gururatana

    2012-01-01

    Full Text Available Problem statement: The performance of electronic devices has been improving along with the rapid technology development. Cooling of electronic systems is consequently essential in controlling the component temperature and avoiding any hot spot. The study aims to review the present electronic cooling methods which are widely used in electronic devices. Approach: There are several methods to cool down the electronics components such as the pin-fin heat sink, confined jet impingement, heat pipe, micro heat sink and so on. Results: The cooling techniques can obviously increase heat transfer rate. Nonetheless, for active and passive cooling methods the pressure drop could extremely rise, when the heat transfer rate is increased. Conclusion: When the cooling techniques are used, it is clearly seen that the heat transfer increases with pressure drop. To avoid excessive expense due to high pressure drop, optimization method is required to obtain optimum cost and cooling rate.

  3. Heat Transfer and Cooling Techniques at Low Temperature

    CERN Document Server

    Baudouy, B

    2014-07-17

    The first part of this chapter gives an introduction to heat transfer and cooling techniques at low temperature. We review the fundamental laws of heat transfer (conduction, convection and radiation) and give useful data specific to cryogenic conditions (thermal contact resistance, total emissivity of materials and heat transfer correlation in forced or boiling flow for example) used in the design of cooling systems. In the second part, we review the main cooling techniques at low temperature, with or without cryogen, from the simplest ones (bath cooling) to the ones involving the use of cryocoolers without forgetting the cooling flow techniques.

  4. Fundamental Research on Convective Heat Transfer in Electronic Cooling Technology

    Institute of Scientific and Technical Information of China (English)

    C.F.Ma; Y.P.Gan; 等

    1992-01-01

    During the past six years comprehensive research programs have been conducted at the Beijing Polytechnic University to provide a better understanding of heat transfer characteristics of existing and condidate cooling techniques for electronic and microelestanding of heat transfer characteristics of existing and condidate cooling techniques for electronic and microleectronic devices.This paper provides a review and summary of the programs with emphasis on direct liquid cooling.Included in this review are the heat transfer investigations related to the following cooling modes:liquid free,mixed and forced convection.liquid jet impingement,flowing liquid film cooling,pool boiling,spray cooling,foreign gas jet impingement in liquid pool,and forced convection air-cooling.

  5. Analysis of Heat Transfer in Actively Cooled Compound Gun Barrel

    Institute of Scientific and Technical Information of China (English)

    WU Bin; XIA Wei

    2005-01-01

    when a gun fires, a large amount of heat is brought in the barrel. Erosion/wear and security problems(self ignition of the propellant) associated with this high thermal energy have to be solved owing to the use of higher combustion gas temperature for improved cannon performance and firing at the sustained high rates. Barrel cooling technologies are the effective measures for addressing this issue. In view of the importance of having knowledge of the heat flux, an approach to calculate heat flux based on measurements was presented and validated. The calculated heat flux is used as the inner boundary condition for modeling heat transfer in a 155 mm mid-wall cooled compound gun barrel. Theoretical analysis and simulated results show that natural air cooling is dramatically slower than the forced liquid mid-wall cooling, accordingly wear life of actively cooled barrel is increased and barrel overheating is prevented.

  6. Advanced turbine cooling, heat transfer, and aerodynamic studies

    Energy Technology Data Exchange (ETDEWEB)

    Je-Chin Han; Schobeiri, M.T. [Texas A& M Univ., College Station, TX (United States)

    1995-10-01

    The contractual work is in three parts: Part I - Effect of rotation on enhanced cooling passage heat transfer, Part II - Effect on Thermal Barrier Coating (TBC) spallation on surface heat transfer, and Part III - Effect of surface roughness and trailing edge ejection on turbine efficiency under unsteady flow conditions. Each section of this paper has been divided into three parts to individually accommodate each part. Part III is further divided into Parts IIIa and IIIb.

  7. Heat and mass transfer problems for film cooling

    Energy Technology Data Exchange (ETDEWEB)

    Leontiev, A.I.

    1999-07-01

    An advance in many branches of engineering is connected with using of more and more high working temperatures, perfection of cooling systems of power installations and further development of the theory of heat transfer. One of the most promising methods of thermal protection of heating surfaces is using of the gas film cooling. Despite intensive development of numerical methods of calculation of film cooling problems, simple and reliable correlations, which are based on clear physical models, that make it possible to generalize experimental data for complex boundary conditions, are necessary for complex engineering calculations. It is well known, that an increase in an initial gas temperature of the gas at the turbine inlet is the basic method to advance technical and economical parameters of the gas turbine units and engines. Modern gas turbine engines are designed to operate at inlet temperatures of 1,800--2,000 K, which are far above the allowable temperatures of the metal. Under these conditions, the turbine blades should be cooled in order to ensure a reasonable lifetime. In the paper the review of calculation methods and of experimental results on heat transfer under film cooling is presented. The effect of an arrangement of film cooling, longitudinal gradient of pressure, nonisothermality and compressibility of gas, swirling of flow, and turbulent pulsations of the main gas flow on effectiveness of the gas film cooling is considered. A method of calculation of combined cooling (film, porous or transpiration and convective) is proposed.

  8. Heat Transfer on a Film-Cooled Rotating Blade

    Science.gov (United States)

    Garg, Vijay K.

    1999-01-01

    A multi-block, three-dimensional Navier-Stokes code has been used to compute heat transfer coefficient on the blade, hub and shroud for a rotating high-pressure turbine blade with 172 film-cooling holes in eight rows. Film cooling effectiveness is also computed on the adiabatic blade. Wilcox's k-omega model is used for modeling the turbulence. Of the eight rows of holes, three are staggered on the shower-head with compound-angled holes. With so many holes on the blade it was somewhat of a challenge to get a good quality grid on and around the blade and in the tip clearance region. The final multi-block grid consists of 4784 elementary blocks which were merged into 276 super blocks. The viscous grid has over 2.2 million cells. Each hole exit, in its true oval shape, has 80 cells within it so that coolant velocity, temperature, k and omega distributions can be specified at these hole exits. It is found that for the given parameters, heat transfer coefficient on the cooled, isothermal blade is highest in the leading edge region and in the tip region. Also, the effectiveness over the cooled, adiabatic blade is the lowest in these regions. Results for an uncooled blade are also shown, providing a direct comparison with those for the cooled blade. Also, the heat transfer coefficient is much higher on the shroud as compared to that on the hub for both the cooled and the uncooled cases.

  9. Spray mist cooling heat transfer in glass tempering process

    Science.gov (United States)

    Sozbir, Nedim; Yao, S. C.

    2016-10-01

    Energy saving is a very important issue in glass plants, especially in a glass tempering process, where very high velocity air jet impingement is applied during the cooling process of glass tempering. In fact, air compressor energy may be reduced by a spray cooling due to its high heat transfer capabilities. Presently, in this paper, both pure air and water mist spray cooling are investigated in the glass tempering process. The test results indicate that thin and low-cost tempered glass can be made by mist cooling without fracture. It is possible to find the optimal water flux and duration of mist application to achieve a desirable temperature distribution in the glass for deep penetration of the cooling front but without inducing cracking during the tempering. The use of mist cooling could give about 29 % air pressure reduction for 2-mm glass plate and 50 % reduction for both 3- and 4-mm glass plates.

  10. Heat Transfer Measurements for a Film Cooled Turbine Vane Cascade

    Science.gov (United States)

    Poinsatte, Philip E.; Heidmann, James D.; Thurman, Douglas R.

    2008-01-01

    Experimental heat transfer and pressure measurements were obtained on a large scale film cooled turbine vane cascade. The objective was to investigate heat transfer on a commercial high pressure first stage turbine vane at near engine Mach and Reynolds number conditions. Additionally blowing ratios and coolant density were also matched. Numerical computations were made with the Glenn-HT code of the same geometry and compared with the experimental results. A transient thermochromic liquid crystal technique was used to obtain steady state heat transfer data on the mid-span geometry of an instrumented vane with 12 rows of circular and shaped film cooling holes. A mixture of SF6 and Argon gases was used for film coolant to match the coolant-to-gas density ratio of a real engine. The exit Mach number and Reynolds number were 0.725 and 2.7 million respectively. Trends from the experimental heat transfer data matched well with the computational prediction, particularly for the film cooled case.

  11. Unsteady conjugate heat transfer analysis for impinging jet cooling

    Science.gov (United States)

    Tejero, F.; Flaszyński, P.; Szwaba, R.; Telega, J.

    2016-10-01

    The paper presents the numerical investigations of the heat transfer on a flat plate cooled by a single impinging jet. The thermal conductivity of the plate was modified from a high thermal case (steel -λ= 35 W/m/K) to a low one (steel alloy Inconel -λ= 9.8 W/m/K). The numerical simulations results are compared with the experimental data from the Institute of Fluid-Flow Machinery Polish Academy of Sciences, Gdansk (Poland). The numerical simulations are carried out by means of Ansys/Fluent and k-ω SST turbulence model and the temperature evolution on the target plate is investigated by conjugated heat transfer computations.

  12. Analyzing the Heat Transfer Property of Heat Pipe Influenced by Integrated Cooling Apparatus

    Directory of Open Access Journals (Sweden)

    Chen-Ching Ting

    2014-01-01

    Full Text Available Heat pipe with discrete heat transfer property is often called thermal superconductor because it has extremely large thermal conductivity. This special heat transfer property is destroyed by integrating cooling apparatus and further reducing the cooling power of a heat pipe cooler. This paper experimentally studied the heat transfer property of heat pipe influenced by integrated cooling apparatus. To simplify the investigating process, a home-made square heat pipe with the dimensions of L×W×H=10×10×100 mm3 was built with two pieces of copper plates and two pieces of glass plates face to face, respectively. The two pieces of copper plates were constructed with inside walls of capillary structure and the two pieces of glasses were with antifog inside walls for observing the inner phenomenon. Moreover, isothermal circulating cooling water was applied outside the heat pipe instead of cooling fin. The results show that heat vapor in the heat pipe is condensed earlier and cannot reach the remote section of condenser. In other words, the heat transfer property of heat pipe is destroyed by integrating cooling water. This phenomenon causes the unfavorable cooling power of the heat pipe cooler.

  13. Heat transfer in two-component internal mist cooling

    Energy Technology Data Exchange (ETDEWEB)

    Novak, V.; Sadowski, D.L.; Schoonover, K.G.; Abdel-Khalik, S.I. [G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801 Ferst Drive, Atlanta, GA 30332-0405 (United States); Ghiaasiaan, S.M. [G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801 Ferst Drive, Atlanta, GA 30332-0405 (United States)], E-mail: mghiaasiaan@gatech.edu

    2008-09-15

    An experimental investigation was conducted to examine steady, internal, nozzle-generated, gas/liquid mist cooling in vertical channels. The ideal primary cooling mechanism in this situation is surface evaporation of an ultra-thin, subcooled liquid film that forms on the heated surface. The aim was to quantify the effects of various operating and design parameters on the cooling effectiveness. Parameters tested included the liquid atomization nozzle design, inlet flow condition (liquid mass fraction; carrier gas velocity, temperature and humidity; liquid temperature; liquid droplet size distribution; and gas/liquid combination), channel characteristics (cross-section geometry, length and surface wettability), and flow direction. Interest in this research has been motivated by the need for a highly efficient cooling mechanism in high-power lasers for inertial fusion reactor applications. A fully instrumented experimental test facility that included three cylindrical and two rectangular electrically heated test sections with different cross-sections and unheated entry lengths was used. The channel hydraulic diameters covered the range 16-26.7 mm, and the heated length-to-hydraulic-diameter ratio varied in the range from 23.3 to 51. Water was used as the mist liquid, with air or helium as the carrier gas. Three types of mist generating nozzles with significantly different spray characteristics were used. Local heat transfer coefficients, defined based on the temperature difference between the heated surface and the bulk gas, were obtained along the channels for a wide range of operating conditions. The data indicate that mist cooling can increase the heat transfer coefficient by more than an order of magnitude compared to forced convection using only the carrier gas.

  14. Turbulence convective heat transfer for cooling the photovoltaic cells

    Science.gov (United States)

    Arianmehr, Iman

    Solar PV (photovoltaic) is a rapidly advancing renewable energy technology which converts sunlight directly into electricity. One of the outstanding challenges of the current PV technology is the reduction in its conversion efficiency with increasing PV panel temperature, which is closely associated with the increase in solar intensity and the ambient temperature surrounding the PV panels. To more effectively capture the available energy when the sun is most intense, significant efforts have been invested in active and passive cooling research over the last few years. While integrated cooling systems can lead to the highest total efficiencies, they are usually neither the most feasible nor the most cost effective solutions. This work examines some simple passive means of manipulating the prevailing wind turbulence to enhance convective heat transfer over a heated plate in a wind tunnel.

  15. Heat transfer problems in gas-cooled solid blankets

    Energy Technology Data Exchange (ETDEWEB)

    Fillo, J.A.; Powell, J.R.

    1976-01-01

    In all fusion reactors using the deuterium-tritium fuel cycle, a large fraction approximately 80 percent of the fusion energy will be released as approximately 14 MeV neutrons which must be slowed down in a relatively thick blanket surrounding the plasma, thereby, converting their kinetic energy to high temperature heat which can be continuously removed by a coolant stream and converted in part to electricity in a conventional power turbine. Because of the primary goal of achieving minimum radioactivity, to date Brookhaven blanket concepts have been restricted to the use of some form of solid lithium, with inert gas-cooling and in some design cases, water-cooling of the shell structure. Aluminum and graphite have been identified as very promising structural materials for fusion blankets, and conceptual designs based on these materials have been made. Depending on the thermal loading on the ''first'' wall which surrounds the plasma as well as blanket design, heat transfer problems may be noticeably different in gas-cooled solid blankets. Approaches to solution of heat removal problems as well as explanation of: (a) the after-heat problems in blankets; (b) tritium breeding in solids; and (c) materials selection for radiation shields relative to the minimum activity blanket efforts at Brookhaven are discussed.

  16. Leading edge film cooling effects on turbine blade heat transfer

    Science.gov (United States)

    Garg, Vijay K.; Gaugler, Raymond E.

    1995-01-01

    An existing three dimensional Navier-Stokes code, modified to include film cooling considerations, has been used to study the effect of spanwise pitch of shower-head holes and coolant to mainstream mass flow ratio on the adiabatic effectiveness and heat transfer coefficient on a film-cooled turbine vane. The mainstream is akin to that under real engine conditions with stagnation temperature = 1900 K and stagnation pressure = 3 MPa. It is found that with the coolant to mainstream mass flow ratio fixed, reducing P, the spanwise pitch for shower-head holes, from 7.5 d to 3.0 d, where d is the hole diameter, increases the average effectiveness considerably over the blade surface. However, when P/d= 7.5, increasing the coolant mass flow increases the effectiveness on the pressure surface but reduces it on the suction surface due to coolant jet lift-off. For P/d = 4.5 or 3.0, such an anomaly does not occur within the range of coolant to mainstream mass flow ratios analyzed. In all cases, adiabatic effectiveness and heat transfer coefficient are highly three-dimensional.

  17. Experimentally Determined Heat Transfer Coefficients for Spacesuit Liquid Cooled Garments

    Science.gov (United States)

    Bue, Grant; Watts, Carly; Rhodes, Richard; Anchondo, Ian; Westheimer, David; Campbell, Colin; Vonau, Walt; Vogel, Matt; Conger, Bruce

    2015-01-01

    A Human-In-The-Loop (HITL) Portable Life Support System 2.0 (PLSS 2.0) test has been conducted at NASA Johnson Space Center in the PLSS Development Laboratory from October 27, 2014 to December 19, 2014. These closed-loop tests of the PLSS 2.0 system integrated with human subjects in the Mark III Suit at 3.7 psi to 4.3 psi above ambient pressure performing treadmill exercise at various metabolic rates from standing rest to 3000 BTU/hr (880 W). The bulk of the PLSS 2.0 was at ambient pressure but effluent water vapor from the Spacesuit Water Membrane Evaporator (SWME) and the Auxiliary Membrane Evaporator (Mini-ME), and effluent carbon dioxide from the Rapid Cycle Amine (RCA) were ported to vacuum to test performance of these components in flight-like conditions. One of the objectives of this test was to determine the heat transfer coefficient (UA) of the Liquid Cooling Garment (LCG). The UA, an important factor for modeling the heat rejection of an LCG, was determined in a variety of conditions by varying inlet water temperature, flowrate, and metabolic rate. Three LCG configurations were tested: the Extravehicular Mobility Unit (EMU) LCG, the Oceaneering Space Systems (OSS) LCG, and the OSS auxiliary LCG. Other factors influencing accurate UA determination, such as overall heat balance, LCG fit, and the skin temperature measurement, will also be discussed.

  18. Numerical investigation of transient heat transfer to hydromagnetic channel flow with radiative heat and convective cooling

    Science.gov (United States)

    Makinde, O. D.; Chinyoka, T.

    2010-12-01

    This present study consists of a numerical investigation of transient heat transfer in channel flow of an electrically conducting variable viscosity Boussinesq fluid in the presence of a magnetic field and thermal radiation. The temperature dependent nature of viscosity is assumed to follow an exponentially model and the system exchanges heat with the ambient following Newton's law of cooling. The governing nonlinear equations of momentum and energy transport are solved numerically using a semi-implicit finite difference method. Solutions are presented in graphical form and given in terms of fluid velocity, fluid temperature, skin friction and heat transfer rate for various parametric values. Our results reveal that combined effect of thermal radiation, magnetic field, viscosity variation and convective cooling have significant impact in controlling the rate of heat transfer in the boundary layer region.

  19. Investigation of heat transfer for extruded polymers cooled in water

    CSIR Research Space (South Africa)

    Kumar, R

    2015-10-01

    Full Text Available part, the time taken by PE, PP and PLA to lose heat in water was analyzed theoretically with the help of MATLAB software package by taking into account the density, thermal conductivity, heat transfer coefficient and specific heat. The time taken...

  20. Heat transfer and core neutronics considerations of the heat pipe cooled thermionic reactor

    Science.gov (United States)

    Determan, W. R.; Lewis, Brian

    1991-01-01

    The authors summarize the results of detailed neutronic and thermal-hydraulic evaluations of the heat pipe cooled thermionic (HPTI) reactor design, identify its key design attributes, and quantify its performance characteristics. The HPTI core uses modular, liquid-metal core heat transfer assemblies to replace the liquid-metal heat transport loop employed by in-core thermionic reactor designs of the past. The nuclear fuel, power conversion, heat transport, and heat rejection functions are all combined into a single modular unit. The reactor/converter assembly uses UN fuel pins to obtain a critical core configuration with in-core safety rods and reflector controls added to complete the subassembly. By thermally bonding the core heat transfer assemblies during the reactor core is coupled neutronically, thermally, and electrically into a modular assembly of individual power sources with cross-tied architecture. A forward-facing heat pipe radiator assembly extends from the reactor head in the shape of a frustum of a cone on the opposite side of the power system from the payload. Important virtues of the concept are the absence of any single-point failures and the ability of the core to effectively transfer the TFE waste heat load laterally to other in-core heat transfer assemblies in the event of multiple failures in either in-core and radiator heat pipes.

  1. Heat transfer and core neutronics considerations of the heat pipe cooled thermionic reactor

    Science.gov (United States)

    Determan, W. R.; Lewis, Brian

    The authors summarize the results of detailed neutronic and thermal-hydraulic evaluations of the heat pipe cooled thermionic (HPTI) reactor design, identify its key design attributes, and quantify its performance characteristics. The HPTI core uses modular, liquid-metal core heat transfer assemblies to replace the liquid-metal heat transport loop employed by in-core thermionic reactor designs of the past. The nuclear fuel, power conversion, heat transport, and heat rejection functions are all combined into a single modular unit. The reactor/converter assembly uses UN fuel pins to obtain a critical core configuration with in-core safety rods and reflector controls added to complete the subassembly. By thermally bonding the core heat transfer assemblies during the reactor core is coupled neutronically, thermally, and electrically into a modular assembly of individual power sources with cross-tied architecture. A forward-facing heat pipe radiator assembly extends from the reactor head in the shape of a frustum of a cone on the opposite side of the power system from the payload. Important virtues of the concept are the absence of any single-point failures and the ability of the core to effectively transfer the TFE waste heat load laterally to other in-core heat transfer assemblies in the event of multiple failures in either in-core and radiator heat pipes.

  2. Heat pipe and surface mass transfer cooling of hypersonic vehicle structures

    Science.gov (United States)

    Colwell, Gene T.; Modlin, James M.

    1992-01-01

    The problem of determining the feasibility of cooling hypersonic vehicle leading-edge structures exposed to severe aerodynamic surface heating using heat pipe and mass transfer cooling techniques is addressed. A description is presented of a numerical finite-difference-based hypersonic leading-edge cooling model incorporating poststartup liquid metal heat pipe cooling with surface transpiration and film cooling to predict the transient structural temperature distributions and maximum surface temperatures of hypersonic vehicle leading edge. An application of this model to the transient cooling of a typical aerospace plane wing leading-edge section. The results of this application indicated that liquid metal heat pipe cooling alone is insufficient to maintain surface temperatures below an assumed maximum level of 1800 K for about one-third of a typical aerospace plane ascent trajectory through the earth's atmosphere.

  3. The lumping of heat transfer parameters in cooled packed beds: effect of the bed entry

    NARCIS (Netherlands)

    Westerink, E.J.; Gerner, J.W.; Gerner, J.W.; Westerterp, K.R.; van der Wal, S.

    1993-01-01

    The lumping of the heat transfer parameters of the one- and the two-dimensional pseudo-homogeneous model of a cooled fixed bed were compared. It appeared that the lumping of the two-dimensional parameters, being the effective radial conductivity h-eff and the heat transfer coefficient at the wall (a

  4. Average Natural Convective Heat Transfer of Air-cooled Condensing Heat Exchanger of Emergency Cooldown Tank - Effect of Tube Banks

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Seon Jeong; Lee, Hee Joon [Kookmin University, Seoul (Korea, Republic of); Kim, Myoung Jun; Moon, Joo Hyung; Bae, Youngmin; Kim, Young-In [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Recently emergency cooldown tank(ECT) is a great concern of passive cooling system for the safety of nuclear reactor. After the operation of a conventional passive cooling system for an extended period, however, the water level falls as a result of the evaporation from the ECT, as steam is emitted from the open top of the tank. In this study, the effect of heat transfer area at the air cooled condensing heat exchanger was investigated by changing 5×5 tube banks into 4×4 and 3×3. Moreover, each of air-side natural convective heat transfer coefficient of tube banks was compared to existing correlations. This study presents the effect of heat transfer area at air-cooled condensing heat exchanger. As heat transfer area decreased, the temperature of outlet increased. In other words, the cooling performance got lower with the decrease of heat transfer area. In addition, the average natural convective heat transfer coefficient was 15.3 W/m{sup 2}/K from the 4×4 tube banks, and 4.92 W/m{sup 2}/K from the 3×3 tube banks, which had quite a large error more than 46% especially with the value of 4×4 tube banks compared to the value from correlation equation. Therefore, according to this result, it is needed to measure the local heat transfer coefficient of vertical cylinder more elaborately in further study.

  5. Study on heat transfer coefficients during cooling of PET bottles for food beverages

    Science.gov (United States)

    Liga, Antonio; Montesanto, Salvatore; Mannella, Gianluca A.; La Carrubba, Vincenzo; Brucato, Valerio; Cammalleri, Marco

    2016-08-01

    The heat transfer properties of different cooling systems dealing with Poly-Ethylene-Terephthalate (PET) bottles were investigated. The heat transfer coefficient (Ug) was measured in various fluid dynamic conditions. Cooling media were either air or water. It was shown that heat transfer coefficients are strongly affected by fluid dynamics conditions, and range from 10 W/m2 K to nearly 400 W/m2 K. PET bottle thickness effect on Ug was shown to become relevant under faster fluid dynamics regimes.

  6. Improving heat transfer in stirred tanks cooled by helical coils

    Directory of Open Access Journals (Sweden)

    S.M.C.P. Pedrosa

    2003-06-01

    Full Text Available Stirred Tank Reactors are extensively used in chemical industries. When they are used for highly exothermic reactions, jackets or coils are employed for heat removal. Internal coils can be either helical or axial and they considerably affect the flow inside the reactor because they impose an additional resistance to flow circulation. The aim of this work is to show that the design of vessels cooled by helical coils can be further improved. The design of these reactors follows very much the geometry proposed by Oldshue and Gretton (1954, and some minor modifications in the coil arrangements are likely to improve internal circulation inside these vessels mainly in the region between coils and wall of the vessel. Results show a gain in performance when small alterations are made specially in the shape of the coil arrangement.

  7. Evaluation of the Impact of Slab Foundation Heat Transfer on Heating and Cooling in Florida

    Energy Technology Data Exchange (ETDEWEB)

    Parker, D. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Kono, J. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Vieira, R. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Gu, L. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States)

    2016-09-01

    During the last three decades of energy-efficiency research, there has been limited study of heat transfer to slab-on-grade foundations in cooling-dominated climates. Most experimental research has focused on the impact of slab-on-grade foundations and insulation schemes on heat losses in heating-dominated climates. This is surprising because the floor area in single-family homes is generally equal to wall area, window area, or attic area, all of which have been extensively evaluated for heat-transfer properties. Moreover, slab foundations are the most common foundation type in cooling-dominated climates. Slab-on-grade construction is very popular in southern states, accounting for 77% of new home floors according to 2014 U.S. Census data. There is a widespread perception that tile flooring, as opposed to carpet, provides a cooler home interior in warm climates. Empirical research is needed because building energy simulation software programs running DOE-2 and EnergyPlus engines often rely on simplified models to evaluate the influence of flooring on interior temperature, even though in some cases more detailed models exist. The U.S. Department of Energy Building America Partnership for Improved Residential Construction (BA-PIRC) performed experiments in the Florida Solar Energy Center’s Flexible Residential Test Facility intended to assess for the first time (1) how slab-on-grade construction influences interior cooling in a cooling-dominated climate and (2) how the difference in a carpeted versus uncarpeted building might influence heating and cooling energy use. Two nominally identical side-by-side residential buildings were evaluated during the course of 1 year, from 2014 to 2015: the east building with a pad and carpet floor and the west building with a bare slab floor. A detailed grid shows temperature measurements taken on the slab surface at various locations as well as at depths of 1.0 ft, 2 ft, 5.0 ft, 10.0 ft, and 20.0 ft below the surface. Temperature

  8. Convective Heat and Mass Transfer in Water at Super—Critical Pressures under Heating or Cooling Conditions in Vertical Tubes

    Institute of Scientific and Technical Information of China (English)

    Pei-XueJiang; Ze-PeiRen; 等

    1995-01-01

    Forced and mixed convection heat and mass transfer are studied numerically for water containing metallic corrosion products in a heated or cooled vertical tube with variable thermophysical properties at super-citical pressures.the fouling mechanisms and fouling models are presented.The influence of variable properties at super-critical pressures on forced or mixed convection has been analyzed.The differences between heat and mass transfer under heating and cooling conditions are discussed.It is found that variable properties,especially buoyancy,greatly influence the fluid flow and heat mass fransfer.

  9. Cooling load optimization of an irreversible refrigerator with combined heat transfer

    Directory of Open Access Journals (Sweden)

    M. El Haj Assad

    2013-01-01

    Full Text Available In this work a mathematical model to study the performance of an irreversible refrigerator has been presented with the consideration of heat exchange by combined convection and radiation. The external irreversibility effects due to finite rate heat transfer as well as the effects of internal dissipations have been considered in the analysis. The relation between the cooling load and the coefficient of performance of the refrigerator has been derived. Furthermore an expression for the maximum cooling rate has been derived. The parameters that affect the cooling load have been investigated. The cooling load has been discussed and the effect of internal irreversibility has been investigated.

  10. Sensible Heat Transfer during Droplet Cooling: Experimental and Numerical Analysis

    Directory of Open Access Journals (Sweden)

    Emanuele Teodori

    2017-06-01

    Full Text Available This study presents the numerical reproduction of the entire surface temperature field resulting from a water droplet spreading on a heated surface, which is compared with experimental data. High-speed infrared thermography of the back side of the surface and high-speed images of the side view of the impinging droplet were used to infer on the solid surface temperature field and on droplet dynamics. Numerical reproduction of the phenomena was performed using OpenFOAM CFD toolbox. An enhanced volume of fluid (VOF model was further modified for this purpose. The proposed modifications include the coupling of temperature fields between the fluid and the solid regions, to account for transient heat conduction within the solid. The results evidence an extremely good agreement between the temporal evolution of the measured and simulated spreading factors of the considered droplet impacts. The numerical and experimental dimensionless surface temperature profiles within the solid surface and along the droplet radius, were also in good agreement. Most of the differences were within the experimental measurements uncertainty. The numerical results allowed relating the solid surface temperature profiles with the fluid flow. During spreading, liquid recirculation within the rim, leads to the appearance of different regions of heat transfer that can be correlated with the vorticity field within the droplet.

  11. Natural Convective Heat and Mass Transfer of Water with Corrosion Products at Super—Critical Pressures under Cooling COnditions

    Institute of Scientific and Technical Information of China (English)

    Pei-XueJiang; Ze-PeiRen; 等

    1993-01-01

    A numerical study is reported of laminar natural convective heat and mass transfer on a vertical cooled plate for water containing metal corrosion products at super-critical pressures.The influence of variable properties at super-critical pressures on natural convertion has been analyzed.The difference between heat and mass transfer under cooling or heating conditions is also discussed and some correlations for heat and mass transfer under cooling conditions are recommended.

  12. The cooling heat transfer characteristics of the supercritical CO2 in micro-fin tube

    Science.gov (United States)

    Lee, Ho-Saeng; Kim, Hyeon-Ju; Yoon, Jung-In; Choi, Kwang-Hwan; Son, Chang-Hyo

    2013-02-01

    This study intended to verify the cooling heat transfer characteristics of supercritical gas for refrigerating and air-conditioning devices that use CO2, a natural refrigerant, as the operating fluid. Experiments were performed with a gas cooler, which was the test part. The gas cooler was a heat exchanger made of a micro-fin tube with an inner diameter of 4.6 mm and an outer diameter of 5.0 mm. The experiment results are summarized as follows. The heat transfer coefficient, according to the mass flux, peaked at the low cooling pressure of 8.0 MPa in the gas cooler, and reached its minimum at the high pressure of 10.0 MPa. Furthermore, when the mass flux of the refrigerant increased, the coefficient increased faster with the lower cooling pressure in the gas cooler. The heat transfer coefficient, according to the shape of the heat transfer tube, showed that the maximum values of the CO2 cooling heat transfer coefficients of the smooth tube and the micro-fin tube were found at 44.7 °C, which were the pseudo-critical temperatures for the entrance pressures. It was found that the cooling heat transfer coefficient of the micro-fin tube increased by 12-39 % more than that of the smooth tube. The experiment results for the CO2 heat transfer coefficients of the smooth tube and the micro-fin tube were compared with the results estimated from previous correlations. It was found that the experiment values generally significantly differed from and the experiment values greater than the estimated values. The differences were especially greater in the vicinity of the critical temperature points. Based on these results, a new correlation was suggested that includes the density ratio and the specific heat ratio.

  13. Heat Transfer Characteristics and Performance of a Spirally Coiled Heat Exchanger under Sensible Cooling Conditions

    Science.gov (United States)

    Wongwises, Somchai; Naphon, Paisarn

    In the present study, new experimental data on the heat transfer characteristics and the performance of a spirally coiled heat exchanger under sensible cooling conditions is presented. The spiral-coil heat exchanger consists of a steel shell and a spirally coiled tube unit. The spiral-coil unit consists of six layers of concentric spirally coiled tubes. Each tube is fabricated by bending a 9.27mm diameter straight copper tube into a spiral-coil of five turns. The innermost and outermost diameters of each spiral-coil are 67.7 and 227.6mm, respectively. Air and water are used as working fluids in shell side and tube side, respectively. A mathematical model based on the conservation of energy is developed to determine the heat transfer characteristics. There is a reasonable agreement between the results obtained from the experiment and those obtained from the model and a good agreement for the high air mass flow rate region. The results obtained from the parametric study are also discussed.

  14. Influence of Different Vortex Generators on Heat Transfer in Direct Air-Cooled Condensers

    Institute of Scientific and Technical Information of China (English)

    ZHOU Guobing; YANG Laishun

    2012-01-01

    With the capacity of air cooling turbines increasing, the air-cooled steam condenser has been developed to the single fiat tube. Fig.1 shows the studied single-row wavy-finned flat tube. Vortex generators are more and more used in oil and chemical industry, power generation, and refrigeration industry in the heat exchanger. The analyses are performed to investigate the effect of vortex generators on pressure drop and heat transfer of single-row wavy-finned fiat tubes of direct air-cooled condensers.

  15. Heat Transfer and Fluid Flow of Nanofluids in Laminar Radial Flow Cooling Systems

    Institute of Scientific and Technical Information of China (English)

    Gilles ROY; Samy Joseph PALM; Cong Tam NGUYEN

    2005-01-01

    Nanofluids are considered as interesting alternatives to conventional coolants. It is well known that traditional fluids have limited heat transfer capabilities when compared to common metals. It is therefore quite conceivable that a small amount of extremely fine metallic particles placed in suspension in traditional fluids will considerably increase their heat transfer performances. A numerical investigation into the heat transfer enhancement capabilities of coolants with suspended metallic nanoparticles inside a radial, laminar flow cooling configuration is presented. Temperature dependant nanofluid properties are evaluated from experimental data available in recent literature. Results indicate that considerable heat transfer increases are possible with the use of relatively small volume fractions of nanoparticles. Generally, however, these are accompanied by considerable increases in wall shear-stress. Results also show that predictions obtained with temperature variable nanofluid properties yield greater heat transfer capabilities and lower wall shear stresses when compared to predictions using constant properties.

  16. The influence of nanoparticle migration on forced convective heat transfer of nanofluid under heating and cooling regimes.

    Science.gov (United States)

    Kozlova, Sofya V; Ryzhkov, Ilya I

    2014-09-01

    In this paper, laminar convective heat transfer of water-alumina nanofluid in a circular tube with uniform heat flux at the tube wall is investigated. The investigation is performed numerically on the basis of two-component model, which takes into account nanoparticle transport by diffusion and thermophoresis. Two thermal regimes at the tube wall, heating and cooling, are considered and the influence of nanoparticle migration on the heat transfer is analyzed comparatively. The intensity of thermophoresis is characterized by a new empirical model for thermophoretic mobility. It is shown that the nanoparticle volume fraction decreases (increases) in the boundary layer near the wall under heating (cooling) due to thermophoresis. The corresponding variations of nanofluid properties and flow characteristics are presented and discussed. The intensity of heat transfer for the model with thermophoresis in comparison to the model without thermophoresis is studied by plotting the dependence of the heat transfer coefficient on the Peclet number. The effectiveness of water-alumina nanofluid is analyzed by plotting the average heat transfer coefficient against the required pumping power. The analysis of the results reveals that the water-alumina nanofluid shows better performance in the heating regime than in the cooling regime due to thermophoretic effect.

  17. Advanced multistage turbine blade aerodynamics, performance, cooling, and heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Fleeter, S.; Lawless, P.B. [Purdue Univ., West Lafayette, IN (United States)

    1995-10-01

    The gas turbine has the potential for power production at the highest possible efficiency. The challenge is to ensure that gas turbines operate at the optimum efficiency so as to use the least fuel and produce minimum emissions. A key component to meeting this challenge is the turbine. Turbine performance, both aerodynamics and heat transfer, is one of the barrier advanced gas turbine development technologies. This is a result of the complex, highly three-dimensional and unsteady flow phenomena in the turbine. Improved turbine aerodynamic performance has been achieved with three-dimensional highly-loaded airfoil designs, accomplished utilizing Euler or Navier-Stokes Computational Fluid Dynamics (CFD) codes. These design codes consider steady flow through isolated blade rows. Thus they do not account for unsteady flow effects. However, unsteady flow effects have a significant impact on performance. Also, CFD codes predict the complete flow field. The experimental verification of these codes has traditionally been accomplished with point data - not corresponding plane field measurements. Thus, although advanced CFD predictions of the highly complex and three-dimensional turbine flow fields are available, corresponding data are not. To improve the design capability for high temperature turbines, a detailed understanding of the highly unsteady and three-dimensional flow through multi-stage turbines is necessary. Thus, unique data are required which quantify the unsteady three-dimensional flow through multi-stage turbine blade rows, including the effect of the film coolant flow. This requires experiments in appropriate research facilities in which complete flow field data, not only point measurements, are obtained and analyzed. Also, as design CFD codes do not account for unsteady flow effects, the next logical challenge and the current thrust in CFD code development is multiple-stage analyses that account for the interactions between neighboring blade rows.

  18. Heat and Mass Transfer of Vacuum Cooling for Porous Foods-Parameter Sensitivity Analysis

    Directory of Open Access Journals (Sweden)

    Zhijun Zhang

    2014-01-01

    Full Text Available Based on the theory of heat and mass transfer, a coupled model for the porous food vacuum cooling process is constructed. Sensitivity analyses of the process to food density, thermal conductivity, specific heat, latent heat of evaporation, diameter of pores, mass transfer coefficient, viscosity of gas, and porosity were examined. The simulation results show that the food density would affect the vacuum cooling process but not the vacuum cooling end temperature. The surface temperature of food was slightly affected and the core temperature is not affected by the changed thermal conductivity. The core temperature and surface temperature are affected by the changed specific heat. The core temperature and surface temperature are affected by the changed latent heat of evaporation. The core temperature is affected by the diameter of pores. But the surface temperature is not affected obviously. The core temperature and surface temperature are not affected by the changed gas viscosity. The parameter sensitivity of mass transfer coefficient is obvious. The core temperature and surface temperature are affected by the changed mass transfer coefficient. In all the simulations, the end temperature of core and surface is not affected. The vacuum cooling process of porous medium is a process controlled by outside process.

  19. Heat transfer analysis during cooling of die with use of water mist

    Directory of Open Access Journals (Sweden)

    R. Władysiak

    2011-07-01

    Full Text Available The paper presents the results of the heat transfer area during the cooling process of steel test die with water mist which consist the flow of air in the range 150÷350 l/min and 0.05 0.24 l/min of water. Temperature change in the thickness of die by means showing with the thermal curves and the temperature gradient and temperature distribution in the space between the nozzle and the cooled surface of the metal mold using a thermal imaging camera and thermocouples measurement. The course of changes in the temperature gradient and the received heat flux from the die while cooling its with the flow of air and water mist stream. It has been shown that the use of water mist with a variable flow of air and water controls the process of heat transfer process between the permanent molds, and a stream of water mist.

  20. Heating, ventilation and cooling

    CSIR Research Space (South Africa)

    Osburn, L

    2009-02-01

    Full Text Available content and is evaporated by the air stream with less moisture. Enthalpy wheels are more effective at transferring energy between the air streams as both sensible and latent heat is transferred. Ground-Coupled Heat Exchanger Ground-coupled heat... with high diurnal temperature variations. Evaporative Coolers Evaporative coolers work on the concept that the evaporation of water has a cooling effect on its immediate environment due to the latent heat that it absorbs in order to evaporate...

  1. Analysis of heat transfer of loop heat pipe used to cool high power LED

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A novel loop heat pipe(LHP)cooling device for high power LED is developed.The thermal capabilities, including startup performance,temperature uniformity and thermal resistance of the loop heat pipe under different heat loads and incline angles have been investigated experimentally.The obtained results indicate that the thermal resistance of the heat pipe heat sink is in the range of 0.19―3.1 K/W,the temperature uniformity in the evaporator is controlled within 1.5℃,and the junction temperature of high power LED can be controlled steadily under 100℃for a heat load of 100 W.

  2. Heat-transfer dynamics during cryogen spray cooling of substrate at different initial temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Jia Wangcun [Beckman Laser Institute, University of California, 1002 Health Sciences Road East, Irvine, CA 92612-1475 (United States); Aguilar, Guillermo [Beckman Laser Institute, University of California, 1002 Health Sciences Road East, Irvine, CA 92612-1475 (United States); Wang Guoxiang [Department of Mechanical Engineering, University of Akron, OH 44325 (United States); Nelson, J Stuart [Beckman Laser Institute, University of California, 1002 Health Sciences Road East, Irvine, CA 92612-1475 (United States)

    2004-12-07

    Cryogen spray cooling (CSC) is used to minimize the risk of epidermal damage during laser dermatologic therapy. However, the dominant mechanisms of heat transfer during the transient cooling process are incompletely understood. The objective of this study is to elucidate the physics of CSC by measuring the effect of initial substrate temperature (T{sub 0}) on cooling dynamics. Cryogen was delivered by a straight-tube nozzle onto a skin phantom. A fast-response thermocouple was used to record the phantom temperature changes before, during and after the cryogen spray. Surface heat fluxes (q'') and heat-transfer coefficients (h) were computed using an inverse heat conduction algorithm. The maximum surface heat flux (q''{sub max}) was observed to increase with T{sub 0}. The surface temperature corresponding to q''{sub max} also increased with T{sub 0} but the latter has no significant effect on h. It is concluded that heat transfer between the cryogen spray and skin phantom remains in the nucleate boiling region even if T{sub 0} is 80 {sup 0}C.

  3. Numerical comparison of convective heat transfer augmentation devices used in cooling channels of hypersonic vehicles

    Science.gov (United States)

    Maldonado, Jaime J.

    1994-01-01

    Hypersonic vehicles are exposed to extreme thermal conditions compared to subsonic aircraft; therefore, some level of thermal management is required to protect the materials used. Normally, hypersonic vehicles experience the highest temperatures in the nozzle throat, and aircraft and propulsion system leading edges. Convective heat transfer augmentation techniques can be used in the thermal management system to increase heat transfer of the cooling channels in those areas. The techniques studied in this report are pin-fin, offset-fin, ribbed and straight roughened channel. A smooth straight channel is used as the baseline for comparing the techniques. SINDA '85, a lumped parameter finite difference thermal analyzer, is used to model the channels. Subroutines are added to model the fluid flow assuming steady one dimensional compressible flow with heat addition and friction. Correlations for convective heat transfer and friction are used in conjunction with the fluid flow analysis mentioned. As expected, the pin-fin arrangement has the highest heat transfer coefficient and the largest pressure drop. All the other devices fall in between the pin-fin and smooth straight channel. The selection of the best heat augmentation method depends on the design requirements. A good approach may be a channel using a combination of the techniques. For instance, several rows of pin-fins may be located at the region of highest heat flux, surrounded by some of the other techniques. Thus, the heat transfer coefficient is maximized at the region of highest heat flux while the pressure drop is not excessive.

  4. Enhancement of heat transfer in Czochralski growth of silicon crystals with a chemical cooling technique

    Science.gov (United States)

    Ding, Junling; Liu, Lijun; Zhao, Wenhan

    2017-06-01

    The cost of producing single-crystalline silicon with the Czochralski method can be reduced by promoting the crystal size and/or crystal pulling rate. However, more latent heat of solidification needs to be released from the melt-crystal (m-c) interface during the crystal growth process. In this study, the C-CO2 chemical endothermic reaction is proposed as a novel and efficient cooling technique to solve this problem. Compared with the conventional gas cooling method, C-CO2 endothermic reaction method can significantly enhance the heat transfer in the crystal at the m-c interface. It was found that the heat transfer is more enhanced with a chemical reaction of smaller activation energy, and the m-c interface becomes flatter. The influence of the carbon concentration in the chemical reactive gas flow on the heat removal in the crystal at the m-c interface is also investigated. The cooling effect is significantly increased with the increase in the carbon concentration when it is small. However, when the carbon concentration in the reactive gas is high, the cooling effect just increases slightly. The research demonstrates that the proposed chemical endothermic reaction is a promising cooling technique to be applied in CZ-Si crystal growth with large size/high pulling rate.

  5. Heat transfer in a bundle cooled with supercritical Freon-12

    Energy Technology Data Exchange (ETDEWEB)

    Peiman, W.; Milner, A.; Pascoe, C.; Patel, H.; Richards, G.; Pioro, I., E-mail: wargha.peiman@mycampus.uoit.ca, E-mail: igor.pioro@uoit.ca [Univ. of Ontario Inst. of Tech., Faculty of Energy Systems and Nuclear Science, Oshawa, Ontario (Canada)

    2010-07-01

    This paper focuses on analyzing experimental data on Freon-12 at a supercritical pressure of 4.65 MPa. Experiments were conducted at the Institute of Physics and Power Engineering in Russia. The test section consisted of a pressure tube, ceramic inserts, a hexagonal flow tube and a vertical 7-element bundle installed inside the flow tube. The seven elements of the bundle were made of stainless steel and had an outer diameter of 9.5 mm and a heated length of one meter. Bulk-fluid temperature of the coolant at the inlet and the outlet of the test section and the temperature profile of the central heated element were recorded using thermocouples. For comparison, bulk-fluid, and sheath temperature profiles were calculated using various correlations and results were compared with the experimental values. (author)

  6. A new simplified model to calculate surface temperature and heat transfer of radiant floor heating and cooling systems

    DEFF Research Database (Denmark)

    Wu, Xiaozhou; Zhao, Jianing; Olesen, Bjarne W.

    2015-01-01

    In this paper, a new simplified model to calculate surface temperature and heat transfer of radiant floor heating and cooling system was proposed and established using the conduction shape factor. Measured data from references were used to validate the proposed model. The results showed that the ......In this paper, a new simplified model to calculate surface temperature and heat transfer of radiant floor heating and cooling system was proposed and established using the conduction shape factor. Measured data from references were used to validate the proposed model. The results showed...... that the maximum differences between the calculated surface temperature and heat transfer using the proposed model and the measured data were 0.8 ºC and 8.1 W/m2 for radiant floor heating system when average water temperature between 40 ºC and 60 ºC. For the corresponding values were 0.3 ºC and 2.0 W/m2...... for radiant floor cooling systems when average water temperature between 10 ºC and 20 ºC. Numerically simulated data in this study were also used to validate the proposed model. The results showed that the surface temperature and heat transfer of radiant floor calculated by the proposed model agreed very well...

  7. Heat transfer coefficient distribution over the inconel plate cooled from high temperature by the array of water jets

    Science.gov (United States)

    Malinowski, Z.; Telejko, T.; Cebo-Rudnicka, A.; Szajding, A.; Rywotycki, M.; Hadała, B.

    2016-09-01

    The industrial rolling mills are equipped with systems for controlled water cooling of hot steel products. A cooling rate affects the final mechanical properties of steel which are strongly dependent on microstructure evolution processes. In case of water jets cooling the heat transfer boundary condition can be defined by the heat transfer coefficient. In the present study one and three dimensional heat conduction models have been employed in the inverse solution to heat transfer coefficient. The inconel plate has been heated to about 900oC and then cooled by one, two and six water jets. The plate temperature has been measured by 30 thermocouples. The heat transfer coefficient distributions at plate surface have been determined in time of cooling.

  8. Heat transfer enhancement in a natural draft dry cooling tower under crosswind operation with heterogeneous water distribution

    Energy Technology Data Exchange (ETDEWEB)

    Goodarzi, Mohsen; Amooie, Hossein [Bu-Ali Sina Univ., Hamedan (Iran, Islamic Republic of). Dept. of Mechanical Engineering

    2016-04-15

    Crosswind significantly decreases cooling efficiency of a natural draft dry cooling tower. The possibility of improving cooling efficiency with heterogeneous water distribution within the cooling tower radiators under crosswind condition is analysed. A CFD approach was used to model the flow field and heat transfer phenomena within the cooling tower and airflow surrounding the cooling tower. A mathematical model was developed from various CFD results. Having used a trained Genetic Algorithm with the result of mathematical model, the best water distribution was found among the others. Remodeling the best water distribution with the CFD approach showed that the highest enhancement of the heat transfer compared to the usual uniform water distribution.

  9. Effect of controlling parameters on heat transfer during spray impingement cooling of steel plate

    Directory of Open Access Journals (Sweden)

    Purna C. Mishra

    2013-09-01

    Full Text Available The heat transfer characteristics of air-water spray impingement cooling of stationary steel plate was experimentally investigated. Experiments were conducted on an electrically heated flat stationary steel plate of dimension 120 mm x 120 mm x 4 mm. The controlling parameters taken during the experiments were airwater pressures, water flow rate, nozzle tip to target distance and mass impingement density. The effects of the controlling parameters on the cooling rates were critically examined during spray impingement cooling. Air assisted DM water was used as the quenchant media in the work. The cooling rates were calculated from the time dependent temperature profiles were recorded by NI-cRIO DAS at the desired locations of the bottom surface of the plate embedded with K-type thermocouples. By using MS-EXCEL the effects of these cooling rate parameters were analysed The results obtained in the study confirmed the higher efficiency of the spray cooling system and the cooling strategy was found advantageous over the conventional cooling methods in the present steel industries

  10. Heat transfer and performance characteristics of axial cooling fans with downstream guide vanes

    Science.gov (United States)

    Terzis, Alexandros; Stylianou, Ioannis; Kalfas, Anestis I.; Ott, Peter

    2012-04-01

    This study examines experimentally the effect of stators on the performance and heat transfer characteristics of small axial cooling fans. A single fan impeller, followed by nine stator blades in the case of a complete stage, was used for all the experimental configurations. Performance measurements were carried out in a constant speed stage performance test rig while the transient liquid crystal technique was used for the heat transfer measurements. Full surface heat transfer coefficient distributions were obtained by recording the temperature history of liquid crystals on a target plate. The experimental data indicated that the results are highly affected by the flow conditions at the fan outlet. Stators can be beneficial in terms of pressure drop and efficiency, and thus more economical operation, as well as, in the local heat transfer distribution at the wake of the stator blades if the fan is installed very close to the cooling object. However, as the separation distance increases, enhanced heat transfer rate in the order of 25% is observed in the case of the fan impeller.

  11. Experimental Study on Cooling Heat Transfer of Supercritical Carbon Dioxide Inside Horizontal Micro-Fin Tubes

    Science.gov (United States)

    Kuwahara, Ken; Higashiiu, Shinya; Ito, Daisuke; Koyama, Shigeru

    This paper deals with the experimental study on cooling heat transfer of supercritical carbon dioxide inside micro-fin tubes. The geometrical parameters in micro-fin tubes used in the present study are 6.02 mm in outer diameter, 4.76 mm to 5.11 mm in average inner diameter, 0.15 mm to 0.24 mm in fin height, 5 to 25 in helix angle, 46 to 52 in number of fins and 1.4 to 2.3 in area expansion ratio. Heat transfer coefficients were measured at 8-10 MPa in pressure, 360-690 kg/(m2•s) in mass velocity and 20-75 °C in CO2 temperature. The measured heat transfer coefficients of micro-fin tubes were 1.4 to 2 times higher than those of the smooth tube having 4.42 in inner diameter. The predicted heat transfer coefficients using the correlation equation, which was developed for single-phase turbulent fluid flow inside micro-fin-tubes, showed large deviations to the measured values. The new correlation to predict cooling heat transfer coefficient of supercritical carbon dioxide inside micro-fin tubes was developed taking into account the shape of fins based on experimental data empirically. This correlation equation agreed within ±20% of almost all of the experimental data.

  12. Conjugate heat transfer investigation on the cooling performance of air cooled turbine blade with thermal barrier coating

    Science.gov (United States)

    Ji, Yongbin; Ma, Chao; Ge, Bing; Zang, Shusheng

    2016-08-01

    A hot wind tunnel of annular cascade test rig is established for measuring temperature distribution on a real gas turbine blade surface with infrared camera. Besides, conjugate heat transfer numerical simulation is performed to obtain cooling efficiency distribution on both blade substrate surface and coating surface for comparison. The effect of thermal barrier coating on the overall cooling performance for blades is compared under varied mass flow rate of coolant, and spatial difference is also discussed. Results indicate that the cooling efficiency in the leading edge and trailing edge areas of the blade is the lowest. The cooling performance is not only influenced by the internal cooling structures layout inside the blade but also by the flow condition of the mainstream in the external cascade path. Thermal barrier effects of the coating vary at different regions of the blade surface, where higher internal cooling performance exists, more effective the thermal barrier will be, which means the thermal protection effect of coatings is remarkable in these regions. At the designed mass flow ratio condition, the cooling efficiency on the pressure side varies by 0.13 for the coating surface and substrate surface, while this value is 0.09 on the suction side.

  13. Heat Transfer Model with Two Heat Transfer Coefficients Along a Multiperforated Plate--Application to Combustion Chamber Wall Cooling

    Institute of Scientific and Technical Information of China (English)

    Brice Pêtre; Eva Dorignac; Jean Jacques Vullierme

    2003-01-01

    Walls'cooling of aeronautic propeller combustion chamber is performed with the injection, through the combustion chamber wall, of a part of the air coming from compressors placed upstream. Measurements of the wall thermal fields are made by infrared thermography along the injection wall. This injection wall is pierced by 9 rows of 8 holes (α=90°) in staggered configuration (p/D=s/D=6). We propose a model using two heat transfer coefficients to represent the convective exchanges. The results are non-dimensioned and presented in comparison with the case without holes. The use of this model allows us to define 4 zones. Those 4 zones exist for the 5 blowing rates.

  14. Experimental Investigation of Convective Heat Transfer during Night Cooling with Different Ventilation Systems and Surface Emissivities

    DEFF Research Database (Denmark)

    Le Dreau, Jerome; Heiselberg, Per; Jensen, Rasmus Lund

    2013-01-01

    Night-time ventilation is a promising approach to reduce the energy needed for cooling buildings without reducing thermal comfort. Nevertheless actual building simulation tools have showed their limits in predicting accurately the efficiency of night-time ventilation, mainly due to inappropriate...... air and the room, and floor emissivities. This extensive experimental study enabled a detailed analysis of the convective and radiative flow at the different surfaces of the room. The experimentally derived convective heat transfer coefficients (CHTC) have been compared to existing correlations...... ventilation, the convective heat transfer was well predicted by existing correlations. Nevertheless the change of floor emissivity influenced the CHTC at the surface of interest....

  15. Validation of Heat Transfer and Film Cooling Capabilities of the 3-D RANS Code TURBO

    Science.gov (United States)

    Shyam, Vikram; Ameri, Ali; Chen, Jen-Ping

    2010-01-01

    The capabilities of the 3-D unsteady RANS code TURBO have been extended to include heat transfer and film cooling applications. The results of simulations performed with the modified code are compared to experiment and to theory, where applicable. Wilcox s k-turbulence model has been implemented to close the RANS equations. Two simulations are conducted: (1) flow over a flat plate and (2) flow over an adiabatic flat plate cooled by one hole inclined at 35 to the free stream. For (1) agreement with theory is found to be excellent for heat transfer, represented by local Nusselt number, and quite good for momentum, as represented by the local skin friction coefficient. This report compares the local skin friction coefficients and Nusselt numbers on a flat plate obtained using Wilcox's k-model with the theory of Blasius. The study looks at laminar and turbulent flows over an adiabatic flat plate and over an isothermal flat plate for two different wall temperatures. It is shown that TURBO is able to accurately predict heat transfer on a flat plate. For (2) TURBO shows good qualitative agreement with film cooling experiments performed on a flat plate with one cooling hole. Quantitatively, film effectiveness is under predicted downstream of the hole.

  16. Use of a laser-induced fluorescence thermal imaging system for film cooling heat transfer measurement

    Energy Technology Data Exchange (ETDEWEB)

    Chyu, M.K. [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    1995-10-01

    This paper describes a novel approach based on fluorescence imaging of thermographic phosphor that enables the simultaneous determination of both local film effectiveness and local heat transfer on a film-cooled surface. The film cooling model demonstrated consists of a single row of three discrete holes on a flat plate. The transient temperature measurement relies on the temperature-sensitive fluorescent properties of europium-doped lanthanum oxysulfide (La{sub 2}O{sub 2}S:EU{sup 3+}) thermographic phosphor. A series of full-field surface temperatures, mainstream temperatures, and coolant film temperatures were acquired during the heating of a test surface. These temperatures are used to calculate the heat transfer coefficients and the film effectiveness simultaneously. Because of the superior spatial resolution capability for the heat transfer data reduced from these temperature frames, the laser-induced fluorescence (LIF) imaging system, the present study observes the detailed heat transfer characteristics over a film-protected surface. The trend of the results agrees with those obtained using other conventional thermal methods, as well as the liquid crystal imaging technique. One major advantage of this technique is the capability to record a large number of temperature frames over a given testing period. This offers multiple-sample consistency.

  17. Heat transfer and film-cooling for the endwall of a first stage turbine vane

    Energy Technology Data Exchange (ETDEWEB)

    Thole, Karen A.; Knost, Daniel G. [Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060 (United States)

    2005-12-01

    Secondary flows that result in turbomachines from inherent pressure gradients in airfoil passages, are the main contributors to aerodynamic losses and high heat transfer to the airfoil endwalls. The endwalls present a challenge to durability engineers in maintaining the integrity of the airfoils. One means of preventing degradation in the turbine is to film-cool components whereby coolant is extracted from the compressor and injected through small cooling holes in the airfoil surfaces. In addition to film-cooling, leakage flows from component interfaces, such as the combustor and turbine, can provide cooling in localized areas but also provide a change to the inlet boundary condition to the passage. This paper presents measurements relevant to the endwall region of a vane, which indicate the importance of considering the inlet flow condition. (author)

  18. Heat transfer in rocket engine combustion chambers and regeneratively cooled nozzles

    Science.gov (United States)

    1993-01-01

    A conjugate heat transfer computational fluid dynamics (CFD) model to describe regenerative cooling in the main combustion chamber and nozzle and in the injector faceplate region for a launch vehicle class liquid rocket engine was developed. An injector model for sprays which treats the fluid as a variable density, single-phase media was formulated, incorporated into a version of the FDNS code, and used to simulate the injector flow typical of that in the Space Shuttle Main Engine (SSME). Various chamber related heat transfer analyses were made to verify the predictive capability of the conjugate heat transfer analysis provided by the FDNS code. The density based version of the FDNS code with the real fluid property models developed was successful in predicting the streamtube combustion of individual injector elements.

  19. SOLAR ABSORBING COOLING SYSTEMS BASED ON MULTISTAGE HEAT-MASS-TRANSFER DEVICES

    Directory of Open Access Journals (Sweden)

    Doroshenko A.V.

    2014-08-01

    Full Text Available The article presents the worked out schematics for the alternative refrigeration systems and of air-conditioning systems, based on the use of absorbing cycle and of the sunny energy for the regeneration (renewals of absorbent solution. We use here the cascade principle of construction of all heat-mass-transfer apparatus with variation of both the temperature level and the growth of absorbent concentration on the cascade stages. The heat-mass-transfer equipment as a part of the drying and cooling units is standardized and is executed by means of multistage monoblock compositions from poly-meric materials. The preliminary analysis of possibilities of the sunny systems in application to the tasks of cooling of environment and air-conditioning systems is carried out.

  20. Heat Transfer on a Film-Cooled Rotating Blade Using a Two-Equation Turbulence Model

    OpenAIRE

    Vijay K Garg

    1998-01-01

    A three-dimensional Navier–Stokes code has been used to compare the heat transfer coefficient on a film-cooled, rotating turbine blade. The blade chosen is the ACE rotor with five rows containing 93 film cooling holes covering the entire span. This is the only filmcooled rotating blade over which experimental data is available for comparison. Over 2.278 million grid points are used to compute the flow over the blade including the tip clearance region, using Coakley's q-ω turbulence model. Res...

  1. Experimental analysis of heat and mass transfer phenomena in a direct contact evaporative cooling tower

    Energy Technology Data Exchange (ETDEWEB)

    Lemouari, M. [Department of Processes Engineering, Faculty of Sciences and Engineering, University of Bejaia (Algeria); Boumaza, M. [Department of Chemical Engineering, College of Engineering - King Saud University, P.O. Box 800, Riyadh (Saudi Arabia); Kaabi, A. [Department of Genie Climatique, Faculty of Engineering, University of Constantine, Constantine (Algeria)

    2009-06-15

    This paper deals with an experimental analysis of simultaneous heat and mass transfer phenomena between water and air by direct contact in a packed cooling tower. The tower is filled with a ''VGA.'' (Vertical Grid Apparatus) type packing. The packing is 0.42 m high and consists of four (04) galvanised sheets having a zigzag form, between which are disposed three (03) metallic vertical grids in parallel with a cross-sectional test area of 0.15 m x 0.148 m. This study investigates the effect of the air and water flow rates on the global heat and mass transfer coefficient as well as the evaporation rate of water into the air stream, for different inlet water temperatures. Two operating regimes were observed during the air/water contact inside the tower, a Pellicular Regime (PR) and a Bubble and Dispersion Regime (BDR). These two regimes can determine the best way to promote the heat and mass transfer phenomena in such device. The BDR regime seems to be more efficient than the Pellicular Regime, as it enables to achieve relatively higher values of the global heat and mass transfer coefficient and larger water evaporation rates. The comparison between the obtained results and some of those available in the literature for other types of packing indicates that this type possesses good heat and mass transfer characteristics. (author)

  2. Heat transfer in a vertical 7-element bundle cooled with supercritical Freon-12

    Energy Technology Data Exchange (ETDEWEB)

    Richards, G.; Milner, A.; Pascoe, C.; Patel, H.; Peiman, W.; Saltanov, Eu. [Univ. of Ontario Inst. of Tech., Faculty of Energy Systems and Nuclear Science, Oshawa, Ontario (Canada); Pometko, R.S.; Opanasenko, A.N. [Inst. of Physics and Power Engineering, Obninsk (Russian Federation); Shelegov, A.S. [IATE, Obninsk (Russian Federation); Kirillov, P.L. [Inst. of Physics and Power Engineering, Obninsk (Russian Federation); Pioro, I. [Univ. of Ontario Inst. of Tech., Faculty of Energy Systems and Nuclear Science, Oshawa, Ontario (Canada)

    2010-07-01

    Currently, SuperCritical Water-cooled nuclear Reactor (SCWR) concepts are being developed worldwide with an objective to increase thermal efficiencies of future Nuclear Power Plants (NPPs) on 10 -15% compared to those of current water-cooled NPPs. With such an increase in the thermal efficiencies, SCW NPPs will be at the current level of the most advanced thermal power plants: coal-fired SCW NPPs and combined-cycle gas-fired NPPs. However, to be able to develop SCWRs at least several key technical problems should be resolved. One of these problems is limited amount of experimental data on heat transfer in fuel bundles and based on that SCW heat-transfer correlations. Experiments in SCW are very complicated and expensive due to high critical parameters of water (pressure 22.064 MPa and temperature 374.95°C). Moreover, there are only few SCW test rigs, which capable to perform experiments in full-scale bundles. As a preliminary approach supercritical-pressure heat-transfer experiments in bundles can be performed in modeling fluids such as Freons or carbon dioxide. Therefore, a set of experimental data was obtained in Freon-12-cooled bundle simulator at the Institute of Physics and Power Engineering (IPPE, Obninsk, Russia). A vertical 7-element bundle was installed in a hexagonal flow channel. The test section consisted of elements that were 9.5 mm in diameter with the total heated length of 1 m. Bulk-fluid and wall temperature profiles were recorded using thermocouples. Several heat-transfer regimes were tested. Also, this paper references thermophysical properties of supercritical Freon-12 at the critical pressure (4.1361 MPa) and test pressure of 4.65 MPa. (author)

  3. Nanofluids for power engineering: Emergency cooling of overheated heat transfer surfaces

    Science.gov (United States)

    Bondarenko, B. I.; Moraru, V. N.; Sidorenko, S. V.; Komysh, D. V.

    2016-07-01

    The possibility of emergency cooling of an overheated heat transfer surface using nanofluids in the case of a boiling crisis is explored by means of synchronous recording of changes of main heat transfer parameters of boiling water over time. Two nanofluids are tested, which are derived from a mixture of natural aluminosilicates (AlSi-7) and titanium dioxide (NF-8). It is found that the introduction of a small portions of nanofluid into a boiling coolant (distilled water) in a state of film boiling ( t heater > 500°C) can dramatically decrease the heat transfer surface temperature to 130-150°C, which corresponds to a transition to a safe nucleate boiling regime without affecting the specific heat flux. The fact that this regime is kept for a long time at a specific heat load exceeding the critical heat flux for water and t heater = 125-130°C is particularly important. This makes it possible to prevent a potential accident emergency (heater burnout and failure of the heat exchanger) and to ensure the smooth operation of the equipment.

  4. ANALYSIS OF HEAT TRANSFER OF WORK ROLL COOLING IN HOT ROLLING

    Directory of Open Access Journals (Sweden)

    Marcio Rodrigo Solimani

    2013-10-01

    Full Text Available The roll cooling in Hot Rolling of flats directly affects two fundamental characteristics of the rolls:.the durability due to surface degradation. The other is the thermal expansion, which affects the shape and dimensions of the strip. Cooling is done by water jets that need to be properly adjusted. The determination of heat transfer coefficients is essential to optimize the process and thus increase its durability and quality of the strip. Results of experimental and numerical effects of cooling using a water jet fan-shaped on a prototype roll at temperatures between 50°C and 350°C are performed. Water pressure, nozzle type and the position along the length of the fan-shaped (center and edge influence the efficiency of roll cooling. The maximum value found in the coefficient of heat transfer was 6.0 kW/m2°C, and a 14.3% difference between the center and end of the jet fan-shaped is observed.

  5. Convection heat transfer from discrete heat sources in a liquid cooled rectangular channel

    Energy Technology Data Exchange (ETDEWEB)

    Bhowmik, H. [Department of Mechanical Engineering, Dhaka University of Engineering and Technology, Gazipur 1700 (Bangladesh); Tso, C.P. [Faculty of Engineering and Technology, Multimedia University, Jalan Ayer Keroh Lama, 75450 Melaka (Malaysia); Tou, K.W.; Tan, F.L. [School of Mechanical and Production Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2005-11-01

    Steady-state experiments are performed to study general convective heat transfer from an in-line four simulated electronic chips in a vertical rectangular channel using water as the working fluid. The experimental data covers a wide range for laminar flow under natural, mixed and forced convection conditions with Reynolds number based on channel hydraulic diameter ranging from 40 to 2220 and Reynolds number based on heat source length ranging from 50 to 2775, respectively. The heat flux ranges from 0.1W/cm{sup 2} to 0.6W/cm{sup 2}. The inlet water temperature is at 24{sup o}C. The effect of heat fluxes, flow rates and geometrical parameters such as chip number are investigated. The experimental results indicate that the heat transfer coefficient is strongly affected by Reynolds number and fully-developed values of heat transfer coefficient are reached before the first chip. Empirical correlations are developed for relations using Nusselt number, Reynolds number and Grashof number, based on channel hydraulic diameter. (author)

  6. Thermal chip fabrication with arrays of sensors and heaters for micro-scale impingement cooling heat transfer analysis and measurements.

    Science.gov (United States)

    Shen, C H; Gau, C

    2004-07-30

    The design and fabrication for a thermal chip with an array of temperature sensors and heaters for study of micro-jet impingement cooling heat transfer process are presented. This thermal chip can minimize the heat loss from the system to the ambient and provide a uniform heat flux along the wall, thus local heat transfer processes along the wall can be measured and obtained. The fabrication procedure presented can reach a chip yield of 100%, and every one of the sensors and heaters on the chip is in good condition. In addition, micro-jet impingement cooling experiments are performed to obtain the micro-scale local heat transfer Nusselt number along the wall. Flow visualization for the micro-impinging jet is also made. The experimental results indicate that both the micro-scale impinging jet flow structure and the heat transfer process along the wall is significantly different from the case of large-scale jet impingement cooling process.

  7. Simulation of the Effects of Cooling Techniques on Turbine Blade Heat Transfer

    Science.gov (United States)

    Shaw, Vince; Fatuzzo, Marco

    Increases in the performance demands of turbo machinery has stimulated the development many new technologies over the last half century. With applications that spread beyond marine, aviation, and power generation, improvements in gas turbine technologies provide a vast impact. High temperatures within the combustion chamber of the gas turbine engine are known to cause an increase in thermal efficiency and power produced by the engine. However, since operating temperatures of these engines reach above 1000 K within the turbine section, the need for advances in material science and cooling techniques to produce functioning engines under these high thermal and dynamic stresses is crucial. As with all research and development, costs related to the production of prototypes can be reduced through the use of computational simulations. By making use of Ansys Simulation Software, the effects of turbine cooling techniques were analyzed. Simulation of the Effects of Cooling Techniques on Turbine Blade Heat Transfer.

  8. Adiabatic Effectiveness and Heat Transfer Coefficient on a Film-Cooled Rotating Blade

    Science.gov (United States)

    Garg, Vijay K.

    1997-01-01

    three-dimensional Navier-Stokes code has been used to compute the adiabatic effectiveness and heat transfer coefficient on a rotating film-cooled turbine blade. The blade chosen is the United Technologies Research Center(UTRC) rotor with five film-cooling rows containing 83 holes, including three rows on the shower head with 49 holes, covering about 86% of the blade span. The mainstream is akin to that under real engine conditions with stagnation temperature 1900 K and stagnation pressure 3 MPa. The blade speed is taken to be 5200 rpm. The adiabatic effectiveness is higher for a rotating blade as compared to that for a stationary blade. Also, the direction of coolant injection from the shower-head holes considerably affects the effectiveness and heat transfer coefficient values on both the pressure and suction surfaces. In all cases the heat transfer coefficient and adiabatic effectiveness are highly three-dimensional in the vicinity of holes but tend to become two-dimensional far downstream.

  9. Radial and temporal variations in surface heat transfer during cryogen spray cooling

    Energy Technology Data Exchange (ETDEWEB)

    Franco, Walfre [Department of Mechanical Engineering, University of California, Riverside, CA 92521 (United States); Liu Jie [Department of Mechanical Engineering, University of California, Riverside, CA 92521 (United States); Wang Guoxiang [Department of Mechanical Engineering, University of Akron, Akron, OH 44325 (United States); Nelson, J Stuart [Beckman Laser Institute, University of California, Irvine, CA 92617 (United States); Aguilar, Guillermo [Department of Mechanical Engineering, University of California, Riverside, CA 92521 (United States)

    2005-01-21

    Cryogen spray cooling (CSC) is a heat extraction process that protects the epidermis from thermal damage during dermatologic laser surgery. The objective of the present work is to investigate radial and temporal variations in the heat transferred through the surface of a skin phantom during CSC. A fast-response thermal sensor is used to measure surface temperatures every 1 mm across a 16 mm diameter of the sprayed surface of the phantom. An analytical expression based on Fourier's law and Duhamel's theorem is used to compute surface heat fluxes from temperature measurements. Results show that radial and temporal variations of the boundary conditions have a strong influence on the homogeneity of heat extraction from the skin phantom. However, there is a subregion of uniform cooling whose size is time dependent. It is also observed that the surface heat flux undergoes a marked dynamic variation, with a maximum heat flux occurring at the centre of the sprayed surface early in the spurt followed by a quick decrease. The study shows that radial and temporal variations of boundary conditions must be taken into account and ideally controlled to guarantee uniform protection during CSC of human skin.

  10. Experimental and numerical investigation of heat transfer and pressure drop for innovative gas cooled systems

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, R., E-mail: rodrigo.leija@kit.edu [Karlsruhe Institute of Technology, Institute for Neutron Physics and Reactor Technology, Hermann-von-Helmholtz No. 1, 76344 Eggenstein-Leopoldshafen (Germany); Buchholz, S. [Gesellschaft für Anlagen- und Reaktorsicherheit GRS mbH, Boltzmannstraße 2, 85748 Garching (Germany); Suikkanen, H. [Lappeenranta University of Technology, LUT Energy, PO Box 20, FI-53851 Lappeenranta (Finland)

    2015-08-15

    Highlights: • Experimental results of the L-STAR within the first stage of THINS project. • CFD validation for the heat transfer and pressure losses in innovative gas cooled systems. • The results indicate a strong dependency Turbulent Prandtl at the rod wall temperature distribution. • Gas loop facility suitable for the investigation of thermohydraulic issues of GFR, however there might be flow instabilities when flow is very low. - Abstract: Heat transfer enhancement through turbulence augmentation is recognized as a key factor for improving the safety and economic conditions in the development of both critical and subcritical innovative advanced gas cooled fast reactors (GFR) and transmutation systems. The L-STAR facility has been designed and erected at the Karlsruhe Institute of Technology (KIT) to study turbulent flow behavior and its heat transfer enhancement characteristics in gas cooled annular channels under a wide range of conditions. The test section consists of an annular hexagonal cross section channel with an inner electrical heater rod element, placed concentrically within the test section, which seeks to simulate the flow area of a fuel rod element in a GFR. The long term objective of the experimental study is to investigate and improve the understanding of complex turbulent convective enhancement mechanisms as well as the friction loss penalties of roughened fuel rods compared to smooth ones and to generate an accurate database for further development of physical models. In the first step, experimental results of the fluid flow with uniform heat release conditions for the smooth heater rod are presented. The pressure drops, as well as the axial temperature profiles along the heater rod surface have been measured at Reynolds numbers in the range from 4000 to 35,000. The experimental results of the first stage were compared with independently conducted CFD analyses performed at Lappeenranta University of Technology (LUT) with the code ANSYS

  11. Study of heat transfer and pressure drop characteristics of air heat exchanger using PCM for free cooling applications

    Directory of Open Access Journals (Sweden)

    Kalaiselvam Sivakumar

    2016-01-01

    Full Text Available Free cooling is the process of storing the cool energy available in the night ambient air and using it during the day. The heat exchanger used in this work is a modular type which is similar to the shell and tube heat exchanger. The shell side is filled with Phase Change Materials (PCM and air flow is through the tubes in the module. The modules of the heat exchanger are arranged one over other with air spacers in between each module. The air space provided in between the module in-creases the retention time of the air for better heat transfer. Transient Computational Fluid Dynamics modeling is carried out for single air passage in a modular heat exchanger. It shows that the PCM phase transition time in the module in which different shape of fins is adopted. The module with rectangular fins has 17.2 % reduction in solidification compared with the plain module. Then steady state numerical analysis is accomplished to the whole module having the fin of high heat transfer, so that pressure drop, flow and thermal characteristics across the module and the air spacers are deter-mined for various air inlet velocities of 0.4 to 1.6 m/s. To validate the computational results, experiments are carried out and the agreement was found to be good.

  12. Heat transfer characteristics of coconut oil as phase change material to room cooling application

    Science.gov (United States)

    Irsyad, M.; Harmen

    2017-03-01

    Thermal comfort in a room is one of human needs in the workplace and dwellings, so that the use of air conditioning system in tropical countries is inevitable. This equipment has an impact on the increase of energy consumption. One method of minimizing the energy use is by using the phase change material (PCM) as thermal energy storage. This material utilizes the temperature difference between day and night for the storage and release of thermal energy. PCM development on application as a material for air cooling inlet, partitioning and interior needs to be supported by the study of heat transfer characteristics when PCM absorbs heat from ambient temperature. This study was conducted to determine the heat transfer characteristics on coconut oil as a phase change material. There are three models of experiments performed in this research. Firstly, an experiment was conducted to analyze the time that was needed by material to phase change by varying the temperature. The second experiment analyzed the heat transfer characteristics of air to PCM naturally convection. The third experiment analyzed the forced convection heat transfer on the surface of the PCM container by varying the air velocity. The data of experimental showed that, increasing ambient air temperature resulted in shorter time for phase change. At temperatures of 30°C, the time for phase change of PCM with the thickness of 8 cm was 1700 min, and it was stable at temperatures of 27°C. Increasing air temperature accelerated the phase change in the material. While for the forced convection heat transfer, PCM could reduce the air temperature in the range of 30 to 35°C at about 1 to 2°C, with a velocity of 1-3 m/s.

  13. Heat transfer technology for internal passages of air-cooled blades for heavy-duty gas turbines.

    Science.gov (United States)

    Weigand, B; Semmler, K; von Wolfersdorf, J

    2001-05-01

    The present review paper, although far from being complete, aims to give an overview about the present state of the art in the field of heat transfer technology for internal cooling of gas turbine blades. After showing some typical modern cooled blades, the different methods to enhance heat transfer in the internal passages of air-cooled blades are discussed. The complicated flows occurring in bends are described in detail, because of their increasing importance for modern cooling designs. A short review about testing of cooling design elements is given, showing the interaction of the different cooling features as well. The special focus of the present review has been put on the cooling of blades for heavy-duty gas turbines, which show several differences compared to aero-engine blades.

  14. Numerical study on film cooling and convective heat transfer characteristics in the cutback region of turbine blade trailing edge

    Directory of Open Access Journals (Sweden)

    Xie Yong-Hui

    2016-01-01

    Full Text Available Gas turbine blade trailing edge is easy to burn out under the exposure of high-temperature gas due to its thin shape. The cooling of this area is an important task in gas turbine blade design. The structure design and analysis of trailing edge is critical because of the complexity of geometry, arrangement of cooling channels, design requirement of strength, and the working condition of high heat flux. In the present paper, a 3-D model of the trailing edge cooling channel is constructed and both structures with and without land are numerically investigated at different blowing ratio. The distributions of film cooling effectiveness and convective heat transfer coefficient on cutback and land surface are analyzed, respectively. According to the results, it is obtained that the distributions of film cooling effectiveness and convective heat transfer coefficient both show the symmetrical characteristics as a result of the periodic structure of the trailing edge. The increase of blowing ratio significantly improves the film cooling effectiveness and convective heat transfer coefficient on the cutback surface, which is beneficial to the cooling of trailing edge. It is also found that the land structure is advantageous for enhancing the streamwise film cooling effectiveness of the trailing edge surface while the film cooling effectiveness on the land surface remains at a low level. Convective heat transfer coefficient exhibits a strong dependency with the blowing ratio, which suggests that film cooling effectiveness and convective heat transfer coefficient must be both considered and analyzed in the design of trailing edge cooling structure.

  15. Influence mechanism on flow and heat transfer characteristics for air-cooled steam condenser cells

    Science.gov (United States)

    He, Wei Feng; Dai, Yi Ping; Li, Mao Qing; Ma, Qing Zhong

    2012-09-01

    Air-cooled steam condensers (ACSCs) have been extensively utilized to reject waste heat in power industry to save water resources. However, ACSC performance is so sensitive to ambient wind that almost all the air-cooled power plants in China are less efficient compared to design conditions. It is shown from previous research that the influence of ambient wind on the cell performance differs from its location in the condenser. As a result, a numerical model including two identical ACSC cells are established, and the different influence on the performance of the cells is demonstrated and analyzed through the computational fluid dynamics method. Despite the great influence from the wind speeds, similar cell performance is obtained for the two cells under both windless and wind speed conditions when the wind parallels to the steam duct. Fan volumetric effectiveness which characterizes the fan performance, as well as the exchanger heat transfer rate, drops obviously with the increasing wind speed, and performance difference between the exchanger pair in the same A-frame also rises continuously. Furthermore, different flow and heat transfer characteristics of the windward and leeward cell are obtained at different wind angles, and ambient wind enhances the performance of the leeward cell, while that of the windward one changes little.

  16. Effect of spurt duration on the heat transfer dynamics during cryogen spray cooling

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, Guillermo [Department of Biomedical Engineering, University of California, Irvine, CA 92697 (United States); Wang, Guo-Xiang [Department of Mechanical Engineering, University of Akron, OH 44325 (United States); Nelson, J Stuart [Department of Biomedical Engineering, University of California, Irvine, CA 92697 (United States)

    2003-07-21

    Although cryogen spray cooling (CSC) is used to minimize the risk of epidermal damage during laser dermatologic surgery, optimization of the current cooling approach is needed to permit the safe use of higher light doses, which should improve the therapeutic outcome in many patients. The objective of this study was to measure the effect of spurt duration ({delta}t) on the heat transfer dynamics during CSC using a model skin phantom. A fast-response temperature sensor was constructed to record the changes in surface temperature during CSC. Temperature measurements as a function of {delta}t at two nozzle-to-skin distances (z = 50 and 20 mm) were performed. The average surface heat fluxes (q) and heat transfer coefficients (h) for each {delta}t were computed using an inverse heat conduction problem algorithm. It was observed that q undergoes a marked dynamic variation during the entire {delta}t, with a maximum heat flux (q{sub c}) occurring early in the spurt (5-15 ms), followed by a quick decrease. The estimated q{sub c} vary from 450 to 600 kW m{sup -2}, corresponding to h maxima of 10 and 17-22 kW m{sup -2} K{sup -1} for z = 50 and 20 mm, respectively. For z = 50 mm, spurts longer than 40 ms do not increase the total heat removal (Q) within the first 200 ms. However, for z = 20 mm, {delta}t longer than 100 ms are required to achieve the same Q. It is shown that the heat transfer dynamics and the time it takes to reach q{sub c} during CSC can be understood through classic boiling theory as a transition from transient to nucleate boiling. Based on the results of this model skin phantom, it is shown that spurts longer than 40 ms have a negligible impact on both q and Q within clinically relevant cooling times (10-100 ms)

  17. Experimental study on the heat transfer characteristics of a nuclear reactor containment wall cooled by gravitationally falling water

    Science.gov (United States)

    Pasek, Ari D.; Umar, Efrison; Suwono, Aryadi; Manalu, Reinhard E. E.

    2012-06-01

    Gravitationally falling water cooling is one of mechanism utilized by a modern nuclear Pressurized Water Reactor (PWR) for its Passive Containment Cooling System (PCCS). Since the cooling is closely related to the safety, water film cooling characteristics of the PCCS should be studied. This paper deals with the experimental study of laminar water film cooling on the containment model wall. The influences of water mass flow rate and wall heat rate on the heat transfer characteristic were studied. This research was started with design and assembly of a containment model equipped with the water cooling system, and calibration of all measurement devices. The containment model is a scaled down model of AP 1000 reactor. Below the containment steam is generated using electrical heaters. The steam heated the containment wall, and then the temperatures of the wall in several positions were measure transiently using thermocouples and data acquisition. The containment was then cooled by falling water sprayed from the top of the containment. The experiments were done for various wall heat rate and cooling water flow rate. The objective of the research is to find the temperature profile along the wall before and after the water cooling applied, prediction of the water film characteristic such as means velocity, thickness and their influence to the heat transfer coefficient. The result of the experiments shows that the wall temperatures significantly drop after being sprayed with water. The thickness of water film increases with increasing water flow rate and remained constant with increasing wall heat rate. The heat transfer coefficient decreases as film mass flow rate increase due to the increases of the film thickness which causes the increasing of the thermal resistance. The heat transfer coefficient increases slightly as the wall heat rate increases. The experimental results were then compared with previous theoretical studied.

  18. Conjugate Heat Transfer Study of Combined Impingement and Showerhead Film Cooling Near NGV Leading Edge

    Directory of Open Access Journals (Sweden)

    Dileep Chandran

    2015-01-01

    Full Text Available A computational and experimental study is carried out on the leading edge region of a typical gas turbine NGV, cooled by a combination of impingement and showerhead film cooling. A detailed flow and conjugate heat transfer study has revealed the complex flow structure owing to the coolant-mainstream interaction and the influence of vane material thermal conductivity. The local effectiveness values obtained by the computations agreed well with the experimental data from IR thermography. The effect of blowing ratio on the overall effectiveness is found to be strongly dependent on the vane material conductivity. The effect of blowing ratio is also found to be different towards the pressure and suction sides of the stagnation region. However, the overall effectiveness is found to decrease by about 12% and 6% for low and high conducting materials, respectively, with an increase in mainstream Reynolds number from Re=4.8×105 to 14.4×105.

  19. Film cooling on a convex wall: Heat transfer and hydrodynamic measurements for full and partial coverage

    Science.gov (United States)

    Furuhama, K.; Moffat, R. J.; Johnston, J. P.; Kays, W. M.

    1985-08-01

    Turbine-blade cooling is an important issue for high-efficiency turbine engines, and discrete-hole injection is widely used as a cooling method. In the present study, detailed measurements were made of the heat transfer and hydrodynamics of a film-cooled flow on a convex wall, both for full and partial coverage. Two important parameters were altered: the blowing ratio, m, and the number of rows of injection holes. Three values of m were tested: m = 0.2, 0.4, and 0.6. In the blown region, m = 0.4 results in the lowest Stanton numbers of the three blowing ratios tested. This indicates that the value of m = 0.4 is near optimum on the convex wall from the point of view of cooling effect by injection. In the recovery region, Stanton numbers gradually approach the no injection values. Although the heat-transfer behavior during recovery from injection looks relatively complicated, the behavior of Stanton number can be explained in terms of two mechanisms: recovery from the thermal effect of injection and recovery from the turbulence augmentation. This interpretation of the data is supported by the hydrodynamic and temperture-profile measurements. For partial blowing cases, the data follow the full-coverage values inside the blown region. In the unblown region, both in the curved and in the flat plate, the effect of the number of blown rows is clearly seen. Hydrodynamic boundary-layer profiles were measured with the aid of a triple hot-water probe. Three mean-velocity components and six turbulence quantities were simultaneously measured, and inside the blown region strong three-dimensionality was observed.

  20. Study of Nano Particles for Enhanced Heat Transfer Characteristics of Base Fluids for Cool Thermal Energy System

    Directory of Open Access Journals (Sweden)

    Promit Choudhury

    2014-04-01

    Full Text Available Reliable heat transfer is very crucial for heat demand and supply related applications where the optimum demand is not met. Cool thermal energy systems are the units which find application in conditioning and preserving items. A colloidal mixture of nano particles in a base fluid tremendously enhances the heat transfer characteristics of the original base fluid and is ideally suited for practical application due to its marvelous characteristics.

  1. Enhancement and performance evaluation for heat transfer of air cooling zone for reduction system of sponge titanium

    Science.gov (United States)

    Wang, Wenhao; Wu, Fuzhong; Jin, Huixin

    2016-05-01

    Since the magnesiothermic reduction employed in current sponge titanium is a highly exothermic reaction, the TiCl4 feed rate is carried out slowly to keep a suitable temperature in reduction reactor, which accounts for an extremely low level of productivity and energy efficiency. In order to shorten the production cycle and improve the energy efficiency, an enhancing scheme is proposed to enhance the heat transfer of air cooling zone for reduction system. The air cooling zone and enhancing scheme are firstly introduced. And then, the heat transfer characteristics of cooling zone are obtained by theoretical analysis and experimental date without enhancing scheme. Finally, the enhancement is analyzed and evaluated. The results show that the fitting results of heat transfer coefficients can be used to evaluate the heat transfer enhancement of cooling zone. Heat sources temperatures have a limited decreasing, heat transfer rate increases obviously with the enhanced cooling, and the TiCl4 feed rate can be increased significantly by 9.61 %. And the measured and calculated results are good enough to meet the design requirements.

  2. Heat transfer in a microvascular network: the effect of heart rate on heating and cooling in reptiles (Pogona barbata and Varanus varius).

    Science.gov (United States)

    Seebacher, F

    2000-03-21

    Thermally-induced changes in heart rate and blood flow in reptiles are believed to be of selective advantage by allowing animal to exert some control over rates of heating and cooling. This notion has become one of the principal paradigms in reptilian thermal physiology. However, the functional significance of changes in heart rate is unclear, because the effect of heart rate and blood flow on total animal heat transfer is not known. I used heat transfer theory to determine the importance of heat transfer by blood flow relative to conduction. I validated theoretical predictions by comparing them with field data from two species of lizard, bearded dragons (Pogona barbata) and lace monitors (Varanus varius). Heart rates measured in free-ranging lizards in the field were significantly higher during heating than during cooling, and heart rates decreased with body mass. Convective heat transfer by blood flow increased with heart rate. Rates of heat transfer by both blood flow and conduction decreased with mass, but the mass scaling exponents were different. Hence, rate of conductive heat transfer decreased more rapidly with increasing mass than did heat transfer by blood flow, so that the relative importance of blood flow in total animal heat transfer increased with mass. The functional significance of changes in heart rate and, hence, rates of heat transfer, in response to heating and cooling in lizards was quantified. For example, by increasing heart rate when entering a heating environment in the morning, and decreasing heart rate when the environment cools in the evening a Pogona can spend up to 44 min longer per day with body temperature within its preferred range. It was concluded that changes in heart rate in response to heating and cooling confer a selective advantage at least on reptiles of mass similar to that of the study animals (0. 21-5.6 kg). Copyright 2000 Academic Press.

  3. Heat transfer and material temperature conditions in the leading edge area of impingement-cooled turbine vanes

    Science.gov (United States)

    Berg, H. P.; Pfaff, K.; Hennecke, D. K.

    The resultant effects on the cooling effectiveness at the leading edge area of an impingement-cooled turbine vane by varying certain geometrical parameters is described with reference to local internal heat transfer coefficients determined from experiment and temperature calculations. The local heat transfer on the cooling-air side is determined experimentally with the aid of the analogy between heat- and mass transfer. The impingement cooling is provided from an inserted sheet-metal containing a single row of holes. The Reynolds Number and several of the cooling geometry parameters were varied. The results demonstrate the high local resolution of the method of measurement, which allows improved analytical treatment of the leading-edge cooling configuration. These experiments also point to the necessity of not always performing model tests under idealized conditions. This becomes very clear in the case of the tests performed on an application-oriented impingement-cooling configuration like that often encountered in engine manufacture. In conclusion, as an example, temperature calculations are employed to demonstrate the effect on the cooling effectiveness of varying the distances between insert and inner surface of the leading edge. It shows how the effectiveness of the leading edge cooling can be increased by simple geometrical measures, which results in a considerable improvement in service life.

  4. Experimental Study on Heat Transfer Enhancement of Natural Circulation Liquid Cooling System for Electronic Component

    Institute of Scientific and Technical Information of China (English)

    张正国; 李倩侠; 方晓明; 本田博司

    2004-01-01

    The present research is an experimental study on heat transfer characteristics of a natural circulation cooling system for electronic components. A smooth chip and two micro-pin-finned chips were tested. The chip is mounted on the base of a rectangular horizontal duct located at the bottom of 250 mm high natural circulation loop.FC-72 is used as a coolant. The test conditions are set that the operation pressure of experimental system is 1. 013× 105 Pa, the flow rate of FC-72 is 150 g/min and the subcoolings are 10 K, 25 K and 35 k, respectively. Effect of the subcooling on nucleate boiling and critical heat flux(CHF) were investigated. The results show that subcoolingis found to significantly affect CHF for all chips and micro-pin-finned chips sharply enhanced the boiling heat transfer, CHF of micro-pin-finned chips are 2.5~3 times as large as that of smooth chip at the same subcooling.

  5. Subchannel analysis and correlation of the Rod Bundle Heat Transfer (RBHT) steam cooling experimental data

    Energy Technology Data Exchange (ETDEWEB)

    Riley, M.P.; Mohanta, L.; Miller, D.J.; Cheung, F.B. [Pennsylvania State Univ., University Park, PA (United States); Bajorek, S.M.; Tien, K.; Hoxie, C.L. [U.S. Nuclear Regulatory Commission, Washington, DC (United States). Office of Nuclear Regulatory Research

    2016-07-15

    A subchannel analysis of the steam cooling data obtained in the Rod Bundle Heat Transfer (RBHT) test facility has been performed in this study to capture the effect of spacer grids on heat transfer. The RBHT test facility has a 7 x 7 rod bundle with heater rods and with seven spacer grids equally spaced along the length of the rods. A method based on the concept of momentum and heat transport analogy has been developed for calculating the subchannel bulk mean temperature from the measured steam temperatures. Over the range of inlet Reynolds number, the local Nusselt number was found to exhibit a minimum value between the upstream and downstream spacer grids. The presence of a spacer grid not only affects the local Nusselt number downstream of the grid but also affects the local Nusselt number upstream of the next grid. A new correlation capturing the effect of Reynolds number on the local flow restructuring downstream as well as upstream of the spacer grids was proposed for the minimum Nusselt number. In addition, a new enhancement factor accounting for the effects of the upstream as well as downstream spacer grids was developed from the RBHT data. The new enhancement factor was found to compare well with the data from the ACHILLLES test facility.

  6. Conjugate Heat Transfer of an Internally Air-Cooled Nozzle Guide Vane and Shrouds

    Directory of Open Access Journals (Sweden)

    Leiyong Jiang

    2014-04-01

    Full Text Available In order to assess the life of gas turbine critical components, it is essential to adequately specify their aerothermodynamic working environments. Steady-state analyses of the flow field and conjugate heat transfer of an internally air-cooled nozzle guide vane (NGV and shrouds of a gas turbine engine at baseline operating conditions are numerically investigated. A high-fidelity CFD model is generated and the simulations are carried out with properly defined boundary conditions. The features of the complicated flow and temperature fields are revealed. In general, the Mach number is lower and the temperature is higher on the NGV pressure side than those on the suction side. There are two high temperature regions on the pressure side, and the temperature across the middle section is relatively low. These findings are closely related to the locations of the holes and outlets of the cooling flow passage, and consistent with the field observations of damaged NGVs. As a technology demonstration, the results provide required information for the life analysis of the NGV/shrouds assembly and improvement of the cooling flow arrangement.

  7. Heat Transfer on a Film-Cooled Rotating Blade Using Different Turbulence Models

    Science.gov (United States)

    Garg, Vijay K.

    1999-01-01

    A three-dimensional Navier Stokes code has been used to compute the heat transfer coefficient on a film-cooled, rotating turbine blade. The blade chosen is the ACE rotor with five rows containing 93 film cooling holes covering the entire span. This is the only film-cooled rotating blade over which experimental data is available for comparison. Over 2.278 million grid points are used to compute the flow over the blade including the tip clearance region. using Wilcox's k-omega model, Coakley's q-omega model, and the zero-equation Baldwin-Lomax (B-L) model. A reasonably good comparison with the experimental data is obtained on the suction surface for all the turbulence models. At the leading edge, the B-L model yields a better comparison than tile two-equation models. On the pressure surface however the comparison between the experimental data and the prediction from the k-omega model is much better than from the other two models. Overall, the k-omega model provides the best comparison with the experimental data. However, the two-equation models require at least 40% more computational resources than the B-L model.

  8. Heat Transfer on a Film-Cooled Rotating Blade Using a Two Equation Turbulence Model

    Science.gov (United States)

    Garg, Vijay K.

    1998-01-01

    A three-dimensional Navier-Stokes code has been used to compare the heat transfer coefficient on a film-cooled, rotating turbine blade. The blade chosen is the ACE rotor with five rows containing 93 film cooling holes covering the entire span. This is the only film-cooled rotating blade over which experimental data is available for comparison. Over 2.278 million grid points are used to compute the flow over the blade including the tip clearance region, using Coakley's q-omega turbulence model. Results are also compared with those obtained by Garg and Abhari (1997) using the zero-equation Baldwin-Lomax (B-L) model. A reasonably good comparison with the experimental data is obtained on the suction surface for both the turbulence models. At the leading edge, the B-L model yields a better comparison than the q-omega model. On the pressure surface, however, the comparison between the experimental data and the prediction from either turbulence model is poor. A potential reason for the discrepancy on the pressure surface could be the presence of unsteady effects due to stator-rotor interaction in the experiments which are not modeled in the present computations. Prediction using the two-equation model is in general poorer than that using the zero-equation model, while the former requires at least 40% more computational resources.

  9. Heat Transfer Analysis to Optimize The Water Cooling Scheme For Combustion Device

    Directory of Open Access Journals (Sweden)

    B. Usha Rani

    2014-08-01

    Full Text Available Thermal Propulsion system is one kind of propulsion system which is used to drive torpedo. The present study focuses mainly on design of combustion device known to be thrust chamber or thrust cylinder. The chamber and nozzle wall and the injector face plate must be made of metals selected for high strength at elevated temperature coupled with good thermal conductivity, resistance to high temperature oxidation. chemical inertness on the coolant on the coolant side, and suitability for the fabrication method to be employed. In the case of certain monopropellants, the metal must not catalyze the decomposition. Although aluminum and copper alloys have been used successfully for combustion chambers and nozzles, stainless steels and carbon steels are in widest use today.A cooling jacket permits the circulation of a coolant, which, in the case of flight engines is usually one of the propellants. Water is the only coolant recommended. The cooling jacket consists of an inner and outer wall. The combustion chamber forms the inner wall and another concentric but larger cylinder provides the outer wall. The space between the walls serves as the coolant passage. The nozzle throat region usually has the highest heat transfer intensity and is, therefore, the most difficult to cool.

  10. Experimental study of the heat transfers and passive cooling potential of a ventilated plenum designed for uniform air distribution

    DEFF Research Database (Denmark)

    Hviid, Christian Anker; Lessing, Julian

    2016-01-01

    suspended ceiling to uniformly distribute the supply air to the occupied zone. This, in effect, increases the thermal mass of the room because the upper slab of the room no longer is isolated from the occupied zone. In this study, the cooling potential of a diffuse ceiling ventilation system...... is investigated by experiments focused toward characterizing the convective heat transfer of the plenum. The heat transfers are quantified from four different air flow rates, the temperature of the air supplied to the plenum and the mean surface temperature, i.e. the total heat transfer coefficient of the plenum...... with unventilated plenum. In conclusion this study disclosed the mean heat transfer of the plenum with an inlet jet of approx. 1.2-0.4 m/s and temperature differences of 0.5-4.5 °C and showed that ventilation supply through the plenum can be used to augment the night cooling potential....

  11. Numerical Investigation on Supercritical Heat Transfer of RP3 Kerosene Flowing inside a Cooling Channel of Scramjet

    Directory of Open Access Journals (Sweden)

    Ning Wang

    2014-06-01

    Full Text Available Supercritical convective heat transfer characteristics of hydrocarbon fuel play a fundamental role in the active cooling technology of scramjet. In this paper, a 2D-axisymmetric numerical study of supercritical heat transfer of RP3 flowing inside the cooling channels of scramjet has been conducted. The main thermophysical properties of RP3, including density, specific heat, and thermal conductivity, are obtained from experimental data, while viscosity is evaluated from a commercial code with a ten-species surrogate. Effects of heat flux, mass flow rate, and inlet temperature on supercritical heat transfer processes have been investigated. Results indicate that when the wall temperature rises above the pseudocritical temperature of RP3, heat transfer coefficient decreases as a result of drastic decrease of the specific heat. The conventional heat transfer correlations, that is, Gnielinski formula, are no longer proper for the supercritical heat transfer of RP3. The modified Jackson and Hall formula, which was proposed for supercritical CO2 and water, gives good prediction except when the wall temperature is near or higher than the pseudocritical temperature.

  12. Heat Transfer on a Film-Cooled Blade - Effect of Hole Physics

    Science.gov (United States)

    Garg, Vijay K.; Rigby, David L.

    1998-01-01

    A multi-block, three-dimensional Navier-Stokes code has been used to study the within-hole and near-hole physics in relation to heat transfer on a film-cooled blade. The flow domain consists of the coolant flow through the plenum and hole-pipes for the three staggered rows of shower-head holes on the VK1 rotor, and the main flow over the blade. A multi-block grid is generated that is nearly orthogonal to the various surfaces. It may be noted that for the VK1 rotor the shower-head holes are inclined at 30 deg. to the spanwise direction, and are normal to the streamwise direction on the blade. Wilcox's k-omega turbulence model is used. The present study provides a much better comparison for the heat transfer coefficient at the blade mid-span with the experimental data than an earlier analysis wherein coolant velocity and temperature distributions were specified at the hole exits rather than extending the computational domain into the hole-pipe and plenum. Details of the distributions of coolant velocity, temperature, k and omega at the hole exits are also presented.

  13. Heat Transfer on a Film-Cooled Blade: Effect of Hole Physics

    Science.gov (United States)

    Garg, Vijay K.; Rigby, David L.

    1999-01-01

    A multiblock, three-dimensional Navier Stokes code has been used to study the within-hole and near-hole physics in relation to heat transfer on a film-cooled blade. The flow domain consists of the coolant flow through the plenum and hole-pipes for the three staggered rows of shower-head holes on the VKI rotor, and the main flow over the blade. A multiblock grid is generated that is nearly orthogonal to the various surfaces. It may be noted that for the VKI rotor the shower-head holes are inclined at 30 deg to the spanwise direction, and are normal to the streamwise direction on the blade. Wilcox's k-omega turbulence model is used. The present study provides a much better comparison for the span-averaged heat transfer coefficient on the blade surface with the experimental data than an earlier analysis wherein coolant velocity and temperature distributions were specified at the hole exits rather than extending the computational domain into the hole-pipe and plenum. Details of the distributions of coolant velocity, temperature, k and omega at the hole exits are also presented.

  14. Heat transfer and turbulence measurements of a film-cooled flow over a convexly curved surface

    Science.gov (United States)

    Furuhama, K.; Moffat, R. J.; Frota, M. N.

    1984-01-01

    Heat transfer and hydrodynamic boundary layer measurements were made in a turbulent boundary layer on a convex surface with 13 rows of injection. Both full- and partial-coverage cases were tested for three blowing ratios: 0.2, 0.4, and 0.6. Heat transfer results are discussed in terms of Stanton number with injection air temperature equal to wall temperature. In the blown region, for both m (blowing ratio) = 0.2 and 0.4, the local response of the boundary layer is dominated by curvature, and m = 0.4 shows higher cooling effects than m = 0.2 or 0.6, as expected, based on flat-plate results. Hydrodynamic measurements with a triple-hot-wire suggest the existence of two streamwise lanes. Lanes containing injection holes are highly affected by injection and show a definite streamwise evolution. Lanes which do not contain holes are not affected much by injection and show little change in the streamwise direction.

  15. Unsteady High Turbulence Effects on Turbine Blade Film Cooling Heat Transfer Performance Using a Transient Liquid Crystal Technique

    Science.gov (United States)

    Han, J. C.; Ekkad, S. V.; Du, H.; Teng, S.

    2000-01-01

    Unsteady wake effect, with and without trailing edge ejection, on detailed heat transfer coefficient and film cooling effectiveness distributions is presented for a downstream film-cooled gas turbine blade. Tests were performed on a five-blade linear cascade at an exit Reynolds number of 5.3 x 10(exp 5). Upstream unsteady wakes were simulated using a spoke-wheel type wake generator. Coolant blowing ratio was varied from 0.4 to 1.2; air and CO2 were used as coolants to simulate different density ratios. Surface heat transfer and film effectiveness distributions were obtained using a transient liquid crystal technique; coolant temperature profiles were determined with a cold wire technique. Results show that Nusselt numbers for a film cooled blade are much higher compared to a blade without film injection. Unsteady wake slightly enhances Nusselt numbers but significantly reduces film effectiveness versus no wake cases. Nusselt numbers increase only slic,htly but film cooling, effectiveness increases significantly with increasing, blowing ratio. Higher density coolant (CO2) provides higher effectiveness at higher blowing ratios (M = 1.2) whereas lower density coolant (Air) provides higher 0 effectiveness at lower blowing ratios (M = 0.8). Trailing edge ejection generally has more effect on film effectiveness than on the heat transfer, typically reducing film effectiveness and enhancing heat transfer. Similar data is also presented for a film cooled cylindrical leading edge model.

  16. Evaluation of radiation heat transfer in porous medial: Application for a pebble bed modular reactor cooled by CO2 gas

    Directory of Open Access Journals (Sweden)

    Sidi-Ali Kamel

    2013-01-01

    Full Text Available This work analyses the contribution of radiation heat transfer in the cooling of a pebble bed modular reactor. The mathematical model, developed for a porous medium, is based on a set of equations applied to an annular geometry. Previous major works dealing with the subject have considered the forced convection mode and often did not take into account the radiation heat transfer. In this work, only free convection and radiation heat transfer are considered. This can occur during the removal of residual heat after shutdown or during an emergency situation. In order to derive the governing equations of radiation heat transfer, a steady-state in an isotropic and emissive porous medium (CO2 is considered. The obtained system of equations is written in a dimensionless form and then solved. In order to evaluate the effect of radiation heat transfer on the total heat removed, an analytical method for solving the system of equations is used. The results allow quantifying both radiation and free convection heat transfer. For the studied situation, they show that, in a pebble bed modular reactor, more than 70% of heat is removed by radiation heat transfer when CO2 is used as the coolant gas.

  17. Experimentally Determined Overall Heat Transfer Coefficients for Spacesuit Liquid Cooled Garments

    Science.gov (United States)

    Bue, Grant; Rhodes, Richard; Anchondo, Ian; Westheimer, David; Campbell, Colin; Vogel, Matt; Vonaue, Walt; Conger, Bruce; Stein, James

    2015-01-01

    A Human-In-The-Loop (HITL) Portable Life Support System 2.0 (PLSS 2.0) test has been conducted at NASA Johnson Space Center in the PLSS Development Laboratory from October 27, 2014 to December 19, 2014. These closed-loop tests of the PLSS 2.0 system integrated with human subjects in the Mark III Suit at 3.7 psi to 4.3 psi above ambient pressure performing treadmill exercise at various metabolic rates from standing rest to 3000 BTU/hr (880 W). The bulk of the PLSS 2.0 was at ambient pressure but effluent water vapor from the Spacesuit Water Membrane Evaporator (SWME) and the Auxiliary Membrane Evaporator (Mini-ME), and effluent carbon dioxide from the Rapid Cycle Amine (RCA) were ported to vacuum to test performance of these components in flight-like conditions. One of the objectives of this test was to determine the overall heat transfer coefficient (UA) of the Liquid Cooling Garment (LCG). The UA, an important factor for modeling the heat rejection of an LCG, was determined in a variety of conditions by varying inlet water temperature, flow rate, and metabolic rate. Three LCG configurations were tested: the Extravehicular Mobility Unit (EMU) LCG, the Oceaneering Space Systems (OSS) LCG, and the OSS auxiliary LCG. Other factors influencing accurate UA determination, such as overall heat balance, LCG fit, and the skin temperature measurement, will also be discussed.

  18. Cool sound: the future of refrigeration? Thermodynamic and heat transfer issues in thermoacoustic refrigeration

    Science.gov (United States)

    Herman, C.; Travnicek, Z.

    2006-04-01

    During the past two decades the thermoacoustic refrigeration and prime mover cycles gained importance in a variety of refrigeration applications. Acoustic work, sound, can be used to generate temperature differences that allow the transport of heat from a low temperature reservoir to an ambient at higher temperature, thus forming a thermoacoustic refrigeration system. The thermoacoustic energy pumping cycle can also be reversed: temperature difference imposed along the stack plates can lead to sound generation. In this situation the thermoacoustic system operates as a prime mover. Sound generated by means of this thermoacoustic energy conversion process can be utilized to drive different types of refrigeration devices that require oscillatory flow for their operation, such as thermoacoustic refrigerators, pulse tubes and Stirling engines. In order for a thermoacoustic refrigeration or prime mover system as well as a thermoacoustic prime mover driving a non-thermoacoustic refrigeration system to be competitive on the current market, it has to be optimized in order to improve its overall performance. Optimization can involve improving the performance of the entire system as well as its components. The paper addresses some of the thermodynamic and heat transfer issues relevant in improving the performance of the thermoacoustic system, such as optimization for maximum COP, maximum cooling load and the role of the heat exchangers. Results obtained using the two optimization criteria are contrasted in the paper to illustrate the complexity of the optimization process.

  19. Fully dry PMMA transfer of graphene on h-BN using a heating/cooling system

    Science.gov (United States)

    Uwanno, T.; Hattori, Y.; Taniguchi, T.; Watanabe, K.; Nagashio, K.

    2015-12-01

    The key to achieve high-quality van der Waals heterostructure devices made of stacking various two-dimensional (2D) layered materials lies in the clean interface without bubbles and wrinkles. Although polymethylmethacrylate (PMMA) is generally used as a sacrificial transfer film due to its strong adhesion property, it is always dissolved in the solvent after the transfer, resulting in the unavoidable PMMA residue on the top surface. This makes it difficult to locate clean interface areas. In this work, we present a fully dry PMMA transfer of graphene onto h-BN using a heating/cooling system which allows identification of clean interface area for high quality graphene/h-BN heterostructure fabrication. The mechanism lies in the utilization of the large difference in thermal expansion coefficients between polymers (PMMA/PDMS) and inorganic materials (graphene/h-BN substrate) to mechanically peel off PMMA from graphene by the thermal shrinkage of polymers, leaving no PMMA residue on the graphene surface. This method can be applied to all types of 2D layered materials.

  20. Control of heat transfer in continuous-feeding Czochralski-silicon crystal growth with a water-cooled jacket

    Science.gov (United States)

    Zhao, Wenhan; Liu, Lijun

    2017-01-01

    The continuous-feeding Czochralski method is an effective method to reduce the cost of single crystal silicon. By promoting the crystal growth rate, the cost can be reduced further. However, more latent heat will be released at the melt-crystal interface under a high crystal growth rate. In this study, a water-cooled jacket was applied to enhance the heat transfer at the melt-crystal interface. Quasi-steady-state numerical calculation was employed to investigate the impact of the water-cooled jacket on the heat transfer at the melt-crystal interface. Latent heat released during the crystal growth process at the melt-crystal interface and absorbed during feedstock melting at the feeding zone was modeled in the simulations. The results show that, by using the water-cooled jacket, heat transfer in the growing crystal is enhanced significantly. Melt-crystal interface deflection and thermal stress increase simultaneously due to the increase of radial temperature at the melt-crystal interface. With a modified heat shield design, heat transfer at the melt-crystal interface is well controlled. The crystal growth rate can be increased by 20%.

  1. Heat transfer analysis of catheters used for localized tissue cooling to attenuate reperfusion injury.

    Science.gov (United States)

    Merrill, Thomas L; Mitchell, Jennifer E; Merrill, Denise R

    2016-08-01

    Recent revascularization success for ischemic stroke patients using stentrievers has created a new opportunity for therapeutic hypothermia. By using short term localized tissue cooling interventional catheters can be used to reduce reperfusion injury and improve neurological outcomes. Using experimental testing and a well-established heat exchanger design approach, the ɛ-NTU method, this paper examines the cooling performance of commercially available catheters as function of four practical parameters: (1) infusion flow rate, (2) catheter location in the body, (3) catheter configuration and design, and (4) cooling approach. While saline batch cooling outperformed closed-loop autologous blood cooling at all equivalent flow rates in terms of lower delivered temperatures and cooling capacity, hemodilution, systemic and local, remains a concern. For clinicians and engineers this paper provides insights for the selection, design, and operation of commercially available catheters used for localized tissue cooling.

  2. Impact of plant shoot architecture on leaf cooling: a coupled heat and mass transfer model.

    Science.gov (United States)

    Bridge, L J; Franklin, K A; Homer, M E

    2013-08-01

    Plants display a range of striking architectural adaptations when grown at elevated temperatures. In the model plant Arabidopsis thaliana, these include elongation of petioles, and increased petiole and leaf angles from the soil surface. The potential physiological significance of these architectural changes remains speculative. We address this issue computationally by formulating a mathematical model and performing numerical simulations, testing the hypothesis that elongated and elevated plant configurations may reflect a leaf-cooling strategy. This sets in place a new basic model of plant water use and interaction with the surrounding air, which couples heat and mass transfer within a plant to water vapour diffusion in the air, using a transpiration term that depends on saturation, temperature and vapour concentration. A two-dimensional, multi-petiole shoot geometry is considered, with added leaf-blade shape detail. Our simulations show that increased petiole length and angle generally result in enhanced transpiration rates and reduced leaf temperatures in well-watered conditions. Furthermore, our computations also reveal plant configurations for which elongation may result in decreased transpiration rate owing to decreased leaf liquid saturation. We offer further qualitative and quantitative insights into the role of architectural parameters as key determinants of leaf-cooling capacity.

  3. Dimensionless Model of a Thermoelectric Cooling Device Operating at Real Heat Transfer Conditions: Maximum Cooling Capacity Mode

    Science.gov (United States)

    Melnikov, A. A.; Kostishin, V. G.; Alenkov, V. V.

    2016-09-01

    Real operating conditions of a thermoelectric cooling device are in the presence of thermal resistances between thermoelectric material and a heat medium or cooling object. They limit performance of a device and should be considered when modeling. Here we propose a dimensionless mathematical steady state model, which takes them into account. Analytical equations for dimensionless cooling capacity, voltage, and coefficient of performance (COP) depending on dimensionless current are given. For improved accuracy a device can be modeled with use of numerical or combined analytical-numerical methods. The results of modeling are in acceptable accordance with experimental results. The case of zero temperature difference between hot and cold heat mediums at which the maximum cooling capacity mode appears is considered in detail. Optimal device parameters for maximal cooling capacity, such as fraction of thermal conductance on the cold side y, fraction of current relative to maximal j' are estimated in range of 0.38-0.44 and 0.48-0.95, respectively, for dimensionless conductance K' = 5-100. Also, a method for determination of thermal resistances of a thermoelectric cooling system is proposed.

  4. Analysis of Fluid Flow and Heat Transfer Model for the Pebble Bed High Temperature Gas Cooled Reactor

    Directory of Open Access Journals (Sweden)

    S. Yamoah

    2012-06-01

    Full Text Available The pebble bed type high temperature gas cooled nuclear reactor is a promising option for next generation reactor technology and has the potential to provide high efficiency and cost effective electricity generation. The reactor unit heat transfer poses a challenge due to the complexity associated with the thermalflow design. Therefore to reliably simulate the flow and heat transport of the pebble bed modular reactor necessitates a heat transfer model that deals with radiation as well as thermal convection and conduction. In this study, a model with the capability to simulate fluid flow and heat transfer in the pebble bed modular reactor core has been developed. The developed model was implemented on a personal computer using FORTRAN 95 programming language. Several important fluid flow and heat transfer parameters have been examined: including the pressure drop over the reactor core, the heat transfer coefficient, the Nusselt number and the effective thermal conductivity of the fuel pebbles. Results obtained from the simulation experiments show a uniform pressure in the radial direction for a core to fuel element diameter (D/d ratio>20 and the heat transfer coefficient increases with increasing temperature and coolant mass flow rate. The model can adequately account for the flow and heat transfer phenomenon and the loss of pressure through friction in the pebble bed type high temperature nuclear reactor.

  5. Effects of Tube Diameter and Tubeside Fin Geometry on the Heat Transfer Performance of Air-Cooled Condensers

    Science.gov (United States)

    Wang, H. S.; Honda, Hiroshi

    A theoretical study has been made on the effects of tube diameter and tubeside fin geometry on the heat transfer performance of air-cooled condensers. Extensive numerical calculations of overall heat transfer from refrigerant R410A flowing inside a horizontal microfin tube to ambient air were conducted for a typical operating condition of the air-cooled condenser. The tubeside heat transfer coefficient was calculated by applying a modified stratified flow model developed by Wang et al.8). The numerical results show that the effects of tube diameter, fin height, fin number and helix angle of groove are significant, whereas those of the width of flat portion at the fin tip, the radius of round corner at the fin tip and the fin half tip angle are small.

  6. Experimental study of convective heat transfer during cooling with low air velocity in a stack of objects

    Energy Technology Data Exchange (ETDEWEB)

    Ben Amara, Sami; Laguerre, Onrawee [Cemagref - Refrigeration Processes Engineering Research Unit, parc de Tourvoie, BP 44, 92163 cedex, Antony (France); Flick, Denis [National Agronomic Institute - INAPG, 16 rue Claude Bernard, 75231 cedex 05, Paris (France)

    2004-12-01

    During cooling with low air velocity (u{<=}0.2 m.s{sup -1}) of a stack of foodstuffs (a few centimeters dimension), the radiation and conduction between products can be of the same order of magnitude as convection. A method was developed to quantify these various transfer modes. The experiment was carried out using an in-line spherical arrangement; however, the same methodology can be applied to other product shapes. The results confirm that the heat transfers by radiation and conduction cannot be neglected. In addition, the convective heat transfer coefficient varies not only with air velocity but also with the product position in the stack. (authors)

  7. Fundamental study of transpiration cooling. [pressure drop and heat transfer data from porous metals

    Science.gov (United States)

    Koh, J. C. Y.; Dutton, J. L.; Benson, B. A.

    1973-01-01

    Isothermal and non-isothermal pressure drop data and heat transfer data generated on porous 304L stainless steel wire forms, sintered spherical stainless steel powder, and sintered spherical OFHC copper powder are reported and correlated. Pressure drop data was collected over a temperature range from 500 R to 2000 R and heat transfer data collected over a heat flux range from 5 to 15 BTU/in2/sec. It was found that flow data could be correlated independently of transpirant temperature and type (i.e., H2, N2). It was also found that no simple relation between heat transfer coefficient and specimen porosity was obtainable.

  8. Secondary flow and heat transfer coefficient distributions in the developing flow region of ribbed turbine blade cooling passages

    Science.gov (United States)

    Forsyth, Peter; McGilvray, Matthew; Gillespie, David R. H.

    2017-01-01

    This paper reports an experimental and numerical study of the development and coupling of aerodynamic flows and heat transfer within a model ribbed internal cooling passage to provide insight into the development of secondary flows. Static instrumentation was installed at the end of a long smooth passage and used to measure local flow features in a series of experiments where ribs were incrementally added upstream. This improves test turnaround time and allows higher-resolution heat transfer coefficient distributions to be captured, using a hybrid transient liquid crystal technique. A composite heat transfer coefficient distribution for a 12-rib-pitch passage is reported: notably the behaviour is dominated by the development of the secondary flow in the passage throughout. Both the aerodynamic and heat transfer test data were compared to numerical simulations developed using a commercial computational fluid dynamics solver. By conducting a number of simulations it was possible to interrogate the validity of the underlying assumptions of the experimental strategy; their validity is discussed. The results capture the developing size and strength of the vortical structures in secondary flow. The local flow field was shown to be strongly coupled to the enhancement of heat transfer coefficient. Comparison of the experimental and numerical data generally shows excellent agreement in the level of heat transfer coefficient predicted, though the numerical simulations fail to capture some local enhancement on both the ribbed and smooth surfaces. Where this was the case, the coupled flow and heat transfer measurements were able to identify missing velocity field characteristics.

  9. Heat Transfer Modeling of an Annular On-Line Spray Water Cooling Process for Electric-Resistance-Welded Steel Pipe.

    Science.gov (United States)

    Chen, Zejun; Han, Huiquan; Ren, Wei; Huang, Guangjie

    2015-01-01

    On-line spray water cooling (OSWC) of electric-resistance-welded (ERW) steel pipes can replace the conventional off-line heat treatment process and become an important and critical procedure. The OSWC process improves production efficiency, decreases costs, and enhances the mechanical properties of ERW steel pipe, especially the impact properties of the weld joint. In this paper, an annular OSWC process is investigated based on an experimental simulation platform that can obtain precise real-time measurements of the temperature of the pipe, the water pressure and flux, etc. The effects of the modes of annular spray water cooling and related cooling parameters on the mechanical properties of the pipe are investigated. The temperature evolutions of the inner and outer walls of the pipe are measured during the spray water cooling process, and the uniformity of mechanical properties along the circumferential and longitudinal directions is investigated. A heat transfer coefficient model of spray water cooling is developed based on measured temperature data in conjunction with simulation using the finite element method. Industrial tests prove the validity of the heat transfer model of a steel pipe undergoing spray water cooling. The research results can provide a basis for the industrial application of the OSWC process in the production of ERW steel pipes.

  10. Heat Transfer Modeling of an Annular On-Line Spray Water Cooling Process for Electric-Resistance-Welded Steel Pipe

    Science.gov (United States)

    Chen, Zejun; Han, Huiquan; Ren, Wei; Huang, Guangjie

    2015-01-01

    On-line spray water cooling (OSWC) of electric-resistance-welded (ERW) steel pipes can replace the conventional off-line heat treatment process and become an important and critical procedure. The OSWC process improves production efficiency, decreases costs, and enhances the mechanical properties of ERW steel pipe, especially the impact properties of the weld joint. In this paper, an annular OSWC process is investigated based on an experimental simulation platform that can obtain precise real-time measurements of the temperature of the pipe, the water pressure and flux, etc. The effects of the modes of annular spray water cooling and related cooling parameters on the mechanical properties of the pipe are investigated. The temperature evolutions of the inner and outer walls of the pipe are measured during the spray water cooling process, and the uniformity of mechanical properties along the circumferential and longitudinal directions is investigated. A heat transfer coefficient model of spray water cooling is developed based on measured temperature data in conjunction with simulation using the finite element method. Industrial tests prove the validity of the heat transfer model of a steel pipe undergoing spray water cooling. The research results can provide a basis for the industrial application of the OSWC process in the production of ERW steel pipes. PMID:26201073

  11. Heat transfer in a channel with inclined target surface cooled by single array of centered impinging jets

    Directory of Open Access Journals (Sweden)

    Al Mubarak Ali A.

    2013-01-01

    Full Text Available An experimental investigation has been carried out to study the heat transfer characteristics in a channel with heated target plate inclined at an angle cooled by single array of equally spaced centered impinging jets for three different jet Reynolds numbers (Re=9300, 14400 and 18800. Air ejected from an array of orifices impinges on the heated target surface The target plate forms the leading edge of a gas turbine blade cooled by jet impingement technique. The work includes the effect of jet Reynolds numbers and feed channel aspect ratios (H/d = 5, 7, 9 where H=2.5, 3.5, 4.5 cm and d=0.5 cm on the heat transfer characteristics for a given orifice jet plate configuration with equally spaced centered holes with outflow exiting in both directions (with inclined heated target surface. In general, It has been observed that, H/d=9 gives the maximum heat transfer over the entire length of the target surface as compared to all feed channel aspect ratios. H/d=9 gives 3% more heat transfer from the target surface as compared to H/d=5 (for Re=14400. Also, it has been observed that the magnitude of the averaged local Nusselt number increases with an increase in the jet Reynolds number for all the feed channel aspect ratios studied.

  12. The effect of ultrasound irradiation on the convective heat transfer rate during immersion cooling of a stationary sphere.

    Science.gov (United States)

    Kiani, Hossein; Sun, Da-Wen; Zhang, Zhihang

    2012-11-01

    It has been proven that ultrasound irradiation can enhance the rate of heat transfer processes. The objective of this work was to study the heat transfer phenomenon, mainly the heat exchange at the surface, as affected by ultrasound irradiation around a stationary copper sphere (k=386W m(-1)K(-1), C(p)=384J kg(-1)K(-1), ρ=8660kg m(-3)) during cooling. The sphere (0.01m in diameter) was immersed in an ethylene glycol-water mixture (-10°C) in an ultrasonic cooling system that included a refrigerated circulator, a flow meter, an ultrasound generator and an ultrasonic bath. The temperature of the sphere was recorded using a data logger equipped with a T-type thermocouple in the center of the sphere. The temperature of the cooling medium was also monitored by four thermocouples situated at different places in the bath. The sphere was located at different positions (0.02, 0.04 and 0.06m) above the transducer surface of the bath calculated considering the center of the sphere as the center of the reference system and was exposed to different intensities of ultrasound (0, 120, 190, 450, 890, 1800, 2800, 3400 and 4100W m(-2)) during cooling. The frequency of the ultrasound was 25kHz. It was demonstrated that ultrasound irradiation can increase the rate of heat transfer significantly, resulting in considerably shorter cooling times. Higher intensities caused higher cooling rates, and Nu values were increased from about 23-27 to 25-108 depending on the intensity of ultrasound and the position of the sphere. However, high intensities of ultrasound led to the generation of heat at the surface of the sphere, thus limiting the lowest final temperature achieved. An analytical solution was developed considering the heat generation and was fitted to the experimental data with R(2) values in the range of 0.910-0.998. Visual observations revealed that both cavitation and acoustic streaming were important for heat transfer phenomenon. Cavitation clouds at the surface of the sphere

  13. An experimental investigation on liquid methane heat transfer enhancement through the use of longitudinal fins in cooling channels

    Science.gov (United States)

    Galvan, Manuel de Jesus

    In the past years, hydrocarbon fuels have been the focus of attention as the interest in developing reusable, high-performing liquid rocket engines has grown. Liquid methane (LCH4) has been of particular interest because of the cost, handling, and storage advantages that it presents when compared to currently used propellants. Deep space exploration requires thrusters that can operate reliably during long-duration missions. One of the challenges in the development of a reliable engine has been providing adequate combustion chamber cooling to prevent engine failure. Regenerative (regen) cooling has presented itself as an appealing option because it provides improved cooling and engine efficiency over other types of cooling, such as film or dump cooling. Due to limited availability of experimental sub-critical liquid methane cooling data for pressure-fed regen engine design, there has been an interest in studying the heat transfer characteristics of the propellant. For this reason, recent experimental studies at the Center for Space Exploration Technology Research (cSETR) at the University of Texas at El Paso (UTEP) have focused on investigating the heat transfer characteristics of sub-critical CH4 flowing through smooth sub-scale cooling channels. In addition to investigating smooth channels, the cSETR has conducted experiments to investigate the effects of internal longitudinal fins on the heat transfer of methane. To conduct the experiments, the cSETR developed a conduction-based thermal concentrator known as the High Heat Flux Test Facility (HHFTF) in which the channels are heated. In this study, a smooth channel and three channels with longitudinal fins all with cross sectional geometries of 3.2 mm x 3.2 mm were tested. The Nusselt numbers ranged from 70 and 510, and Reynolds numbers were between 50,000 and 128,000. Sub-cooled film-boiling phenomena were discovered in the data pertaining to the smooth and two finned channels. Sub-cooled film-boiling was not

  14. Heat Transfer and Friction Characteristics of the Microfluidic Heat Sink with Variously-Shaped Ribs for Chip Cooling

    Directory of Open Access Journals (Sweden)

    Gui-Lian Wang

    2015-04-01

    Full Text Available This paper experimentally and numerically investigated the heat transfer and friction characteristics of microfluidic heat sinks with variously-shaped micro-ribs, i.e., rectangular, triangular and semicircular ribs. The micro-ribs were fabricated on the sidewalls of microfluidic channels by a surface-micromachining micro-electro-mechanical system (MEMS process and used as turbulators to improve the heat transfer rate of the microfluidic heat sink. The results indicate that the utilizing of micro-ribs provides a better heat transfer rate, but also increases the pressure drop penalty for microchannels. Furthermore, the heat transfer and friction characteristics of the microchannels are strongly affected by the rib shape. In comparison, the triangular ribbed microchannel possesses the highest Nusselt number and friction factor among the three rib types.

  15. Heat transfer and friction characteristics of the microfluidic heat sink with variously-shaped ribs for chip cooling.

    Science.gov (United States)

    Wang, Gui-Lian; Yang, Da-Wei; Wang, Yan; Niu, Di; Zhao, Xiao-Lin; Ding, Gui-Fu

    2015-04-22

    This paper experimentally and numerically investigated the heat transfer and friction characteristics of microfluidic heat sinks with variously-shaped micro-ribs, i.e., rectangular, triangular and semicircular ribs. The micro-ribs were fabricated on the sidewalls of microfluidic channels by a surface-micromachining micro-electro-mechanical system (MEMS) process and used as turbulators to improve the heat transfer rate of the microfluidic heat sink. The results indicate that the utilizing of micro-ribs provides a better heat transfer rate, but also increases the pressure drop penalty for microchannels. Furthermore, the heat transfer and friction characteristics of the microchannels are strongly affected by the rib shape. In comparison, the triangular ribbed microchannel possesses the highest Nusselt number and friction factor among the three rib types.

  16. A look-up table for trans-critical heat transfer in water-cooled tubes

    Energy Technology Data Exchange (ETDEWEB)

    Zahlan, H.; Tavoularis, S., E-mail: stavros.tavoularis@uottawa.ca; Groeneveld, D.C.

    2015-04-15

    Highlights: • A new look-up table has been created for high subcritical and supercritical heat transfer. • The table is more accurate than previous methods. • The table can be expanded to account for different effects. - Abstract: This article describes the development and validation of a trans-critical heat transfer look-up table for water at high subcritical and supercritical pressures. As a basis for constructing the table, an extensive database of near-critical and supercritical heat transfer measurements was compiled and upgraded by the rejection of unreliable or inappropriate data, the removal of duplicates and outliers and the reduction of data scatter. A large number of available single-phase and supercritical heat transfer correlations were assessed against the database and the most accurate correlations for each heat transfer regime were identified. These correlations were then used to construct a skeleton table, which provides values of the heat transfer coefficient for a matrix of combinations of 11 values of pressure in the range from 19 to 30 MPa, 9 values of mass flux in the range from 100 to 5000 kg/m{sup 2} s, 17 values of bulk enthalpy in the range from 1000 to 3000 kJ/kg, and 8 values of wall superheat in the range from 10 to 500 K. For the construction of the final table, the predictions of correlations were replaced by experimental values, adjusted following established trends to conform to the skeleton table value matrix. Unlike all previous prediction methods, the table applies not only to normal heat transfer conditions but also to conditions with heat transfer deterioration and enhancement, as it includes data obtained under such conditions. The table values were further adjusted so that apparent discontinuities that were not related to physically plausible changes in heat transfer were smoothened out. The predictions of the table were assessed statistically against the experimental database. When compared to predictions of other

  17. Conjugate Heat Transfer Study at Interior Surface of NGV Leading Edge with Combined Shower Head and Impingement Cooling

    Directory of Open Access Journals (Sweden)

    Arun Kumar Pujari

    2014-01-01

    Full Text Available A computational study on conjugate heat transfer is carried out to present the behavior of nondimensional temperature and heat transfer coefficient of a Nozzle Guide Vane (NGV leading edge. Reynolds number of both mainstream flow and coolant impinging jets are varied. The NGV has five rows of film cooling holes arranged in shower head manner and four rows of impingement holes arranged in staggered manner. The results are presented by considering materials of different thermal conductivity. The results show that the mainstream flow affects the temperature distribution on the interior side of the vane leading edge for high conductivity material whereas it has negligible effects for low conductivity material. The effect of changing blowing ratio on internal heat transfer coefficient and internal surface temperature is also presented.

  18. Numerical investigations of transient heat transfer characteristics and vitrification tendencies in ultra-fast cell cooling processes.

    Science.gov (United States)

    Jiao, Anjun; Han, Xu; Critser, John K; Ma, Hongbin

    2006-06-01

    During freezing, cells are often damaged directly or indirectly by ice formation. Vitrification is an alternative approach to cryopreservation that avoids ice formation. The common method to achieve vitrification is to use relatively high concentrations of cryoprotectant agents (CPA) in combination with a relatively slow cooling rate. However, high concentrations of CPAs have potentially damaging toxic and/or osmotic effects on cells. Therefore, establishing methods to achieve vitrification with lower concentrations of CPAs through ultra-fast cooling rates would be advantageous in these aspects. These ultra-fast cooling rates can be realized by a cooling system with an ultra-high heat transfer coefficient (h) between the sample and coolant. The oscillating motion heat pipe (OHP), a novel cooling device utilizing the pressure change to excite the oscillation motion of the liquid plugs and vapor bubbles, can significantly increase h and may fulfill this aim. The current investigation was designed to numerically study the effects of different values of h on the transient heat transfer characteristics and vitrification tendencies of the cell suspension during the cooling processes in an ultra-thin straw (100 microm in diameter). The transient temperature distribution, the cooling rate and the volume ratio (x) of the ice quantity to the maximum crystallizable ice of the suspension were calculated. From these numerical results, it is concluded that the ultra-high h (>10(4) W/m2 K) obtained by OHPs could facilitate vitrification by efficiently decreasing x as well as the time to pass through the dangerous temperature region where the maximum ice formation happens. For comparison, OHPs can decrease both of the parameters to less than 20% of those from the widely used open pulled straw methods. Therefore, the OHP method will be a promising approach to improving vitrification tendencies of CPA solutions and could also decrease the required concentration of CPAs for

  19. Measurements and computational analysis of heat transfer and flow in a simulated turbine blade internal cooling passage

    Science.gov (United States)

    Russell, Louis M.; Thurman, Douglas R.; Simonyi, Patricia S.; Hippensteele, Steven A.; Poinsatte, Philip E.

    1993-01-01

    Visual and quantitative information was obtained on heat transfer and flow in a branched-duct test section that had several significant features of an internal cooling passage of a turbine blade. The objective of this study was to generate a set of experimental data that could be used to validate computer codes for internal cooling systems. Surface heat transfer coefficients and entrance flow conditions were measured at entrance Reynolds numbers of 45,000, 335,000, and 726,000. The heat transfer data were obtained using an Inconel heater sheet attached to the surface and coated with liquid crystals. Visual and quantitative flow field results using particle image velocimetry were also obtained for a plane at mid channel height for a Reynolds number of 45,000. The flow was seeded with polystyrene particles and illuminated by a laser light sheet. Computational results were determined for the same configurations and at matching Reynolds numbers; these surface heat transfer coefficients and flow velocities were computed with a commercially available code. The experimental and computational results were compared. Although some general trends did agree, there were inconsistencies in the temperature patterns as well as in the numerical results. These inconsistencies strongly suggest the need for further computational studies on complicated geometries such as the one studied.

  20. Convective Heat Transfer with and without Film Cooling in High Temperature, Fuel Rich and Lean Environments

    Science.gov (United States)

    2014-09-01

    the test section, a metal sleeve was placed around the entire ceramic transition as seen at the bottom left of Fig. 3.4. Despite the structural...Wade, W. R. Measurements of Total Hemispherical Emissivity of Several Stably Oxidized Metals and Some Refractory Oxide Coatings. Technical report...materials. Ceramics are capable of withstanding the high Taw condition but crack after repeated heating and cooling cycles. Thus, ceramics not viable in

  1. Parametric investigation on transient boiling heat transfer of metal rod cooled rapidly in water pool

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chi Young [Department of Fire Protection Engineering, Pukyong National University, 45, Yongso-ro, Nam-gu, Busan 48513 (Korea, Republic of); Kim, Sunwoo, E-mail: swkim@alaska.edu [Mechanical Engineering Department, University of Alaska Fairbanks, P. O. Box 755905, Fairbanks, AK 99775-5905 (United States)

    2017-03-15

    Highlights: • Effects of liquid subcooling, surface coating, material property, and surface oxidation are examined. • Liquid subcooling affects remarkably the quenching phenomena. • Cr-coated surfaces for ATF might extend the quenching duration. • Solids with low heat capacity shorten the quenching duration. • Surface oxidation can affect strongly the film boiling heat transfer and MFB point. - Abstract: In this work, the effects of liquid subcooling, surface coating, material property, and surface oxidation on transient pool boiling heat transfer were investigated experimentally using the vertical metal rod and quenching method. The change in rod temperature was measured with time during quenching, and the visualization of boiling around the test specimen was performed using the high-speed video camera. As the test materials, the zircaloy (Zry), stainless steel (SS), niobium (Nb), and copper (Cu) were tested. In addition, the chromium-coated niobium (Cr-Nb) and chromium-coated stainless steel (Cr-SS) were prepared for accident tolerant fuel (ATF) application. Low liquid subcooling and Cr-coating shifted the quenching curve to the right, which indicates a prolongation of quenching duration. On the other hand, the material with small heat capacity and surface oxidation caused the quenching curve to move to the left. To examine the influence of the material property and surface oxidation on the film boiling heat transfer performance and minimum film boiling (MFB) point in more detail, the wall temperature and heat flux were calculated from the present transient temperature profile using the inverse heat transfer analysis, and then the curves of wall temperature and heat flux in the film boiling regime were obtained. In the present experimental conditions, the effect of material property on the film boiling heat transfer performance and MFB point seemed to be minor. On the other hand, based on the experimental results of the Cu test specimen, the surface

  2. Heat transfer in electrical insulation of LHC cables cooled with superfluid helium

    CERN Document Server

    Meuris, C; Leroy, D; Szeless, Balázs

    1999-01-01

    The electrical insulation of the Large Hadron Collider (LHC) cables constitutes a thermal barrier between the conductor and the superfluid helium bath. This can prevent removal of the heat dissipated in the cable by the current rise in the dipoles or by the beam losses. The main experimental results, obtained with stacks of insulated conductors representing a piece of the actual coil, are given. The mock-ups vary only by the material composition and the structure of the electrical insulation. Analysis of the temperature distribution measured in the conductors as a function of the dissipated heat power makes it possible to determine the dominant heat transfer mode in each type of tested insulation and to classify these according to their permeability to superfluid helium. Thermal numerical modelling of the experimental mock-ups clarifies the heat transfer path in the complex structure of the insulation and enables calculation of values of the thermal quantities characteristic of each insulation. The results of...

  3. Effect of plenum crossflow on heat (mass) transfer near and within the entrance of film cooling holes

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, R.J. [Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Mechanical Engineering; Cho, H.H. [Yonsei Univ., Seoul (Korea, Republic of). Dept. of Mechanical Engineering; Jabbari, M.Y. [Saginaw Valley State Univ., University Center, MI (United States). Dept. of Mechanical Engineering

    1997-10-01

    Convective heat/mass transfer near and within the entrance region of film cooling holes supplied with air from an internal duct (plenum) behind the cooling holes has been measured using a naphthalene sublimation technique. The experiments are conducted for duct Reynolds number, based on the duct inlet flow condition, of 1,800 to 13,500, which results in a range of hole Reynolds numbers of 8000 to 30,000, close to actual engine operating conditions. The flow entering the hole can be considered a combination of flow along a 90 deg tube bend and a sudden contraction duct flow. The flow separates at the inner corner and a secondary flow is induced by the centrifugal force associated with the streamline curvature. The mass transfer coefficient for the duct wall (surface of film-cooled plate) with a cooling hole is three to five times higher than for a fully developed duct flow. With a smaller duct, the overall transfer coefficient on the hole entrance surface increases due to the higher duct Reynolds numbers, but the flow has less secondary flow effects within the smaller space. Generally, transfer coefficients on the hole entrance surface are largely unaffected by the duct end presence, but the transfer coefficient is larger downstream for a short distance from the center of the last hole to the duct end. In tests with multiple film cooling holes, the flow at the first hole is more of a curved duct flow (strong secondary flow) and the flow at the last hole is more of a sink-like flow. At the middle hole, the flow is a combination of both flows. The mass transfer rates on the inner hole surfaces are found to be the same for holes with corresponding positions relative to the duct end, although the total number of open holes is different.

  4. Comparison of Two-Equation Turbulence Models for Prediction of Heat Transfer on Film-Cooled Turbine Blades

    Science.gov (United States)

    Garg, Vijay K.; Ameri, Ali A.

    1997-01-01

    A three-dimensional Navier-Stokes code has been used to compute the heat transfer coefficient on two film-cooled turbine blades, namely, the VKI rotor with six rows of cooling holes, including three rows on the shower head and the C3X vane with nine rows of holes, including five rows on the shower head. Predictions of heat transfer coefficient at the blade surface using three two-equation turbulence model specifically, Coakley's q-omega model, Chien's k-epsilon model and Wilcox's k-omega model with Menter's modifications, have been compared with the experimental data of Camci and Arts for the VKI rotor, and of Hylton et al. for the C3X vane along with predictions using the Baldwin-Lomar (B-L) model taken from Garg and Gaugler. It is found that for the cases considered here the two equation models predict the blade heat transfer somewhat better than the B-L model except immediately downstream of the film-cooled holes on the suction surface of the VKI rotor, and over most of the suction surface of the C3X vane. However, all two-equation models require 40% more computer core than the B-L model for solution, and while the q-omega and k-epsilon models need 40% more computer time than the B-L model the k-omega model requires at least 65% more time because of the slower rate of convergence. It is found that the heat transfer coefficient exhibit a strong spanwise as well as streamwise variation for both blades and all turbulence models.

  5. Heat transfer on HLM cooled wire-spaced fuel pin bundle simulator in the NACIE-UP facility

    Energy Technology Data Exchange (ETDEWEB)

    Di Piazza, Ivan, E-mail: ivan.dipiazza@enea.it [Italian National Agency for New Technologies, Energy and Sustainable Economic Development, C.R. ENEA Brasimone, Camugnano (Italy); Angelucci, Morena; Marinari, Ranieri [University of Pisa, Dipartimento di Ingegneria Civile e Industriale, Pisa (Italy); Tarantino, Mariano [Italian National Agency for New Technologies, Energy and Sustainable Economic Development, C.R. ENEA Brasimone, Camugnano (Italy); Forgione, Nicola [University of Pisa, Dipartimento di Ingegneria Civile e Industriale, Pisa (Italy)

    2016-04-15

    Highlights: • Experiments with a wire-wrapped 19-pin fuel bundle cooled by LBE. • Wall and bulk temperature measurements at three axial positions. • Heat transfer and error analysis in the range of low mass flow rates and Péclet number. • Comparison of local and section-averaged Nusselt number with correlations. - Abstract: The NACIE-UP experimental facility at the ENEA Brasimone Research Centre (Italy) allowed to evaluate the heat transfer coefficient of a wire-spaced fuel bundle cooled by lead-bismuth eutectic (LBE). Lead or lead-bismuth eutectic are very attractive as coolants for the GEN-IV fast reactors due to the good thermo-physical properties and the capability to fulfil the GEN-IV goals. Nevertheless, few experimental data on heat transfer with heavy liquid metals (HLM) are available in literature. Furthermore, just a few data can be identified on the specific topic of wire-spaced fuel bundle cooled by HLM. Additional analysis on thermo-fluid dynamic behaviour of the HLM inside the subchannels of a rod bundle is necessary to support the design and safety assessment of GEN. IV/ADS reactors. In this context, a wire-spaced 19-pin fuel bundle was installed inside the NACIE-UP facility. The pin bundle is equipped with 67 thermocouples to monitor temperatures and analyse the heat transfer behaviour in different sub-channels and axial positions. The experimental campaign was part of the SEARCH FP7 EU project to support the development of the MYRRHA irradiation facility (SCK-CEN). Natural and mixed circulation flow regimes were investigated, with subchannel Reynolds number in the range Re = 1000–10,000 and heat flux in the range q″ = 50–500 kW/m{sup 2}. Local Nusselt numbers were calculated for five sub-channels in different ranks at three axial positions. Section-averaged Nusselt number was also defined and calculated. Local Nusselt data showed good consistency with some of the correlation existing in literature for heat transfer in liquid metals

  6. Numerical Simulation of Heat Transfer in Porous Metals for Cooling Applications

    Science.gov (United States)

    Gauna, Edgar Avalos; Zhao, Yuyuan

    2017-08-01

    Porous metals have low densities and novel physical, mechanical, thermal, electrical, and acoustic properties. Hence, they have attracted a large amount of interest over the last few decades. One of their applications is for thermal management in the electronics industry because of their fluid permeability and thermal conductivity. The heat transfer capability is achieved by the interaction between the internal channels within the porous metal and the coolant flowing through them. This paper studies the fluid flow and heat transfer in open-cell porous metals manufactured by space holder methods by numerical simulation using software ANSYS Fluent. A 3D geometric model of the porous structure was created based on the face-centered-cubic arrangement of spheres linked by cylinders. This model allows for different combinations of pore parameters including a wide range of porosity (50 to 80 pct), pore size (400 to 1000 µm), and metal particle size (10 to 75 µm). In this study, water was used as the coolant and copper was selected as the metal matrix. The flow rate was varied in the Darcian and Forchheimer's regimes. The permeability, form drag coefficient, and heat transfer coefficient were calculated under a range of conditions. The numerical results showed that permeability increased whereas the form drag coefficient decreased with porosity. Both permeability and form drag coefficient increased with pore size. Increasing flow rate and decreasing porosity led to better heat transfer performance.

  7. BEM/FDM Conjugate Heat Transfer Analysis of a Two-dimensional Air-cooled Turbine Blade Boundary Layer

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A coupled boundary element method (BEM) and finite difference method (FDM) are applied to solve conjugate heat transfer problem of a two-dimensional air-cooled turbine blade boundary layer. A loosely coupled strategy is adopted, in which each set of field equations is solved to provide boundary conditions for the other. The Navier-Stokes equations are solved by HIT-NS code. In this code, the FDM is adopted and is used to resolve the convective heat transfer in the fluid region. The BEM code is used to resolve the conduction heat transfer in the solid region. An iterated convergence criterion is the continuity of temperature and heat flux at the fluid-solid interface. The numerical results from the BEM adopted in this paper are in good agreement with the results of analyrical solution and the results of commercial code, such as Fluent 6.2. The BEM avoids the complicated mesh needed in other computation method and saves the computation time. The results prove that the BEM adopted in this paper can give the same precision in numerical results with less boundary points. Comparing the conjugate results with the numerical results of an adiabatic wall flow solution, it reveals a significant difference in the distribution of metal temperatures. The results from conjugate heat transfer analysis are more accurate and they are closer to realistic thermal environment of turbines.

  8. Heat pipe turbine vane cooling

    Energy Technology Data Exchange (ETDEWEB)

    Langston, L.; Faghri, A. [Univ. of Connecticut, Storrs, CT (United States)

    1995-10-01

    The applicability of using heat pipe principles to cool gas turbine vanes is addressed in this beginning program. This innovative concept involves fitting out the vane interior as a heat pipe and extending the vane into an adjacent heat sink, thus transferring the vane incident heat transfer through the heat pipe to heat sink. This design provides an extremely high heat transfer rate and an uniform temperature along the vane due to the internal change of phase of the heat pipe working fluid. Furthermore, this technology can also eliminate hot spots at the vane leading and trailing edges and increase the vane life by preventing thermal fatigue cracking. There is also the possibility of requiring no bleed air from the compressor, and therefore eliminating engine performance losses resulting from the diversion of compressor discharge air. Significant improvement in gas turbine performance can be achieved by using heat pipe technology in place of conventional air cooled vanes. A detailed numerical analysis of a heat pipe vane will be made and an experimental model will be designed in the first year of this new program.

  9. Study of heat transfer in a 7-element bundle cooled with the upward flow of supercritical Freon-12

    Science.gov (United States)

    Richards, Graham

    Experimental data on SuperCritical-Water (SCW) cooled bundles are very limited. Major problems with performing such experiments are: 1) small number of operating SCW experimental setups and 2) difficulties in testing and experimental costs at very high pressures, temperatures and heat fluxes. However, SuperCritical Water-cooled nuclear Reactor (SCWRs) designs cannot be finalized without such data. Therefore, as a preliminary approach experiments in SCW-cooled bare tubes and in bundles cooled with SC modeling fluids can be used. One of the SC modeling fluids typically used is Freon- 12 (R-12) where the critical pressure is 4.136 MPa and the critical temperature is 111.97ºC. These conditions correspond to a critical pressure of 22.064 MPa and critical temperature of 373.95ºC in water. A set of experimental data obtained in a Freon-12 cooled vertical bare bundle at the Institute of Physics and Power Engineering (IPPE, Obninsk, Russia) was analyzed. This set consisted of 20 cases of a vertically oriented 7-element bundle installed in a hexagonal flow channel. To secure the bundle in the flow channel 3 thin spacers were used. The dataset was obtained at equivalent parameters of the proposed SCWR concepts. Data was collected at pressures of about 4.65 MPa for several different combinations of wall and bulk-fluid temperatures that were below, at, or above the pseudocritical temperature. Heat fluxes ranged from 9 kW/m2 to 120 kW/m2 and mass fluxes ranged from 440 kg/m2s to 1320 kg/m2s. Also inlet temperatures ranged from 70ºC -- 120ºC. The test section consisted of fuel elements that were 9.5 mm in diameter with the total heated length of 1 m. Bulk-fluid and wall temperature profiles were recorded using a combination of 8 different thermocouples. The data was analyzed with respect to its temperature profile and heat transfer coefficient along the heated length of the test section. In a previous study it was confirmed that there is the existence of three distinct

  10. Analysis of Heat Transfer in Berman Flow of Nanofluids with Navier Slip, Viscous Dissipation, and Convective Cooling

    Directory of Open Access Journals (Sweden)

    O. D. Makinde

    2014-01-01

    Full Text Available Heat transfer characteristics of a Berman flow of water based nanofluids containing copper (Cu and alumina (Al2O3 as nanoparticles in a porous channel with Navier slip, viscous dissipation, and convective cooling are investigated. It is assumed that the exchange of heat with the ambient surrounding takes place at the channel walls following Newton’s law of cooling. The governing partial differential equations and boundary conditions are converted into a set of nonlinear ordinary differential equations using appropriate similarity transformations. These equations are solved analytically by regular perturbation methods with series improvement technique and numerically using an efficient Runge-Kutta Fehlberg integration technique coupled with shooting scheme. The effects of the governing parameters on the dimensionless velocity, temperature, skin friction, pressure drop, and Nusselt numbers are presented graphically and discussed quantitatively.

  11. Experimental investigation of the influence of the air jet trajectory on convective heat transfer in buildings equipped with air-based and radiant cooling systems

    DEFF Research Database (Denmark)

    Le Dreau, Jerome; Heiselberg, Per; Jensen, Rasmus Lund

    2015-01-01

    The complexity and diversity of airflow in buildings make the accurate definition of convective heat transfer coefficients (CHTCs) difficult. In a full-scale test facility, the convective heat transfer of two cooling systems (active chilled beam and radiant wall) has been investigated under steady......-state and dynamic conditions. With the air-based cooling system, a dependency of the convective heat transfer on the air jet trajectory has been observed. New correlations have been developed, introducing a modified Archimedes number to account for the air flow pattern. The accuracy of the new correlations has been...... evaluated to±15%. Besides the study with an air-based cooling system, the convective heat transfer with a radiant cooling system has also been investigated. The convective flow at the activated surface is mainly driven by natural convection. For other surfaces, the complexity of the flow and the large...

  12. Effects of Hot Streak and Phantom Cooling on Heat Transfer in a Cooled Turbine Stage Including Particulate Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bons, Jeffrey [The Ohio State Univ., Columbus, OH (United States); Ameri, Ali [The Ohio State Univ., Columbus, OH (United States)

    2016-01-08

    The objective of this research effort was to develop a validated computational modeling capability for the characterization of the effects of hot streaks and particulate deposition on the heat load of modern gas turbines. This was accomplished with a multi-faceted approach including analytical, experimental, and computational components. A 1-year no cost extension request was approved for this effort, so the total duration was 4 years. The research effort succeeded in its ultimate objective by leveraging extensive experimental deposition studies complemented by computational modeling. Experiments were conducted with hot streaks, vane cooling, and combinations of hot streaks with vane cooling. These studies contributed to a significant body of corporate knowledge of deposition, in combination with particle rebound and deposition studies funded by other agencies, to provide suitable conditions for the development of a new model. The model includes the following physical phenomena: elastic deformation, plastic deformation, adhesion, and shear removal. It also incorporates material property sensitivity to temperature and tangential-normal velocity rebound cross-dependencies observed in experiments. The model is well-suited for incorporation in CFD simulations of complex gas turbine flows due to its algebraic (explicit) formulation. This report contains model predictions compared to coefficient of restitution data available in the open literature as well as deposition results from two different high temperature turbine deposition facilities. While the model comparisons with experiments are in many cases promising, several key aspects of particle deposition remain elusive. The simple phenomenological nature of the model allows for parametric dependencies to be evaluated in a straightforward manner. This effort also included the first-ever full turbine stage deposition model published in the open literature. The simulations included hot streaks and simulated vane cooling

  13. Three dimensional simulation of nucleate boiling heat and mass transfer in cooling passages of internal combustion engines

    Science.gov (United States)

    Mehdipour, R.; Baniamerian, Z.; Delauré, Y.

    2016-05-01

    An accurate knowledge of heat transfer and temperature distribution in vehicle engines is essential to have a good management of heat transfer performance in combustion engines. This may be achieved by numerical simulation of flow through the engine cooling passages; but the task becomes particularly challenging when boiling occurs. Neglecting two phase flow processes in the simulation would however result in significant inaccuracy in the predictions. In this study a three dimensional numerical model is proposed using Fluent 6.3 to simulate heat transfer of fluid flowing through channels of conventional size. Results of the present theoretical and numerical model are then compared with some empirical results. For high fluid flow velocities, departure between experimental and numerical results is about 9 %, while for lower velocity conditions, the model inaccuracy increases to 18 %. One of the outstanding capabilities of the present model, beside its ability to simulate two phase fluid flow and heat transfer in three dimensions, is the prediction of the location of bubble formation and condensation which can be a key issue in the evaluation of the engine performance and thermal stresses.

  14. Theoretical prediction of the effect of heat transfer parameters on cooling rates of liquid-filled plastic straws used for cryopreservation of spermatozoa.

    Science.gov (United States)

    Sansinen, M; Santos, M V; Zaritzky, N; Baez, R; Chirife, J

    2010-01-01

    Heat transfer plays a key role in cryopreservation of liquid semen in plastic straws. The effect of several parameters on the cooling rate of a liquid-filled polypropylene straw when plunged into liquid nitrogen was investigated using a theoretical model. The geometry of the straw containing the liquid was assimilated as two concentric finite cylinders of different materials: the fluid and the straw; the unsteady-state heat conduction equation for concentric cylinders was numerically solved. Parameters studied include external (convection) heat transfer coefficient (h), the thermal properties of straw manufacturing material and wall thickness. It was concluded that the single most important parameter affecting the cooling rate of a liquid column contained in a straw is the external heat transfer coefficient in LN2. Consequently, in order to attain maximum cooling rates, conditions have to be designed to obtain the highest possible heat transfer coefficient when the plastic straw is plunged in liquid nitrogen.

  15. Heat and mass transfer with evaporation cooling of a porous plate

    Science.gov (United States)

    Makarova, S. N.; Shibaev, A. A.

    2016-10-01

    In this paper the results of experimental and theoretical investigation of heat and mass transfer with adiabatic evaporation of bicomponent water/ethanol fluid to an air flow are presented. An innovative test section for the wind tunnel with an active thermal stabilization system, maintaining the cuvette temperature equal to the evaporation surface temperature, is used to provide the evaporation adiabatic conditions. The wall temperature obtained experimentally shows the presence of expressed quasi-stationary evaporation area, qualitatively similar to sublimation curves of volatile organometallic compounds. A theoretical model based on the similarity of heat and mass transfer processes for each of the evaporating solution component is suggested. This model allows to determine evaporation surface temperature (sublimation temperature) accounting for radiation effect.

  16. Kerosene-alumina nanofluid flow and heat transfer for cooling application

    Institute of Scientific and Technical Information of China (English)

    M Mahmoodi; Sh Kandelousi

    2016-01-01

    Kerosene−alumina nanofluid flow and heat transfer in the presence of magnetic field are studied. The basic partial differential equations are reduced to ordinary differential equations which are solved semi analytically using differential transformation method. Velocity and temperature profiles as well as the skin friction coefficient and the Nusselt number are determined analytically. The influence of pertinent parameters such as magnetic parameter, nanofluid volume fraction, viscosity parameter and Eckert number on the flow and heat transfer characteristics is discussed. Results indicate that skin friction coefficient decreases with increase of magnetic parameter, nanofluid volume fraction and viscosity parameter. Nusselt number increases with increase of magnetic parameter and nanofluid volume fraction while it decreases with increase of Eckert number and viscosity parameter.

  17. Core flows and heat transfer induced by inhomogeneous cooling with sub- and supercritical convection

    CERN Document Server

    Dietrich, Wieland; Wicht, Johannes

    2016-01-01

    The amount and spatial pattern of heat extracted from cores of terrestrial planets is ultimately controlled by the thermal structure of the lower rocky mantle. Using the most common model to tackle this problem, a rapidly rotating and differentially cooled spherical shell containing an incompressible and viscous liquid is numerically investigated. To gain the physical basics, we consider a simple, equatorial symmetric perturbation of the CMB heat flux shaped as a spherical harmonic $Y_{11}$. The thermodynamic properties of the induced flows mainly depend on the degree of nonlinearity parametrised by a horizontal Rayleigh number $Ra_h=q^\\ast Ra$, where $q^\\ast$ is the relative CMB heat flux anomaly amplitude and $Ra$ is the Rayleigh number which controls radial buoyancy-driven convection. Depending on $Ra_h$ we characterise three flow regimes through their spatial patterns, heat transport and flow speed scalings: in the linear conductive regime the radial inward flow is found to be phase shifted $90^\\circ$ eas...

  18. Heat transfer performance comparison of steam and air in gas turbine cooling channels with different rib angles

    Science.gov (United States)

    Shi, Xiaojun; Gao, Jianmin; Xu, Liang; Li, Fajin

    2013-11-01

    Using steam as working fluid to replace compressed air is a promising cooling technology for internal cooling passages of blades and vanes. The local heat transfer characteristics and the thermal performance of steam flow in wide aspect ratio channels ( W/ H = 2) with different angled ribs on two opposite walls have been experimentally investigated in this paper. The averaged Nusselt number ratios and the friction factor ratios of steam and air in four ribbed channels were also measured under the same test conditions for comparison. The Reynolds number range is 6,000-70,000. The rib angles are 90°, 60°, 45°, and 30°, respectively. The rib height to hydraulic diameter ratio is 0.047. The pitch-to-rib height ratio is 10. The results show that the Nusselt number ratios of steam are 1.19-1.32 times greater than those of air over the range of Reynolds numbers studied. For wide aspect ratio channels using steam as the coolant, the 60° angled ribs has the best heat transfer performance and is recommended for cooling design.

  19. Investigation on heat transfer characteristic and optimization of the cooling air inlet for the twin-web turbine disk

    Science.gov (United States)

    Zhang, Mengchuang; Gou, Wenxuan; Yao, Qin; Li, Lei; Yue, Zhufeng

    2017-08-01

    With a higher operation temperature, the conventional aero-turbine single web disk (SWD) has reached its limits. The twin-web disk (TWD) has been designed as a breakthrough, which has an expected performance in weight loss, strength and heat transfer efficiency. However, the lack of investigation on the position of the cooling air inlet is slowing down further application of TWD. Therefore, for a further study, inlet position optimization with maximum average Nusselt number is conducted for TWD flow structure study. The average Nusselt number result shows that the TWD has a better performance in heat transfer. All the works, including modeling and analyzing, can be referred for engineering design. And the conclusions obtained in this paper could be valuable for the future improvement of the TWD.

  20. A mathematical model of endovascular heat transfer for human brain cooling

    Science.gov (United States)

    Salsac, Anne-Virginie; Lasheras, Juan Carlos; Yon, Steven; Magers, Mike; Dobak, John

    2000-11-01

    Selective cooling of the brain has been shown to exhibit protective effects in cerebral ischemia, trauma, and spinal injury/ischemia. A multi-compartment, unsteady thermal model of the response of the human brain to endovascular cooling is discussed and its results compared to recent experimental data conducted with sheep and other mammals. The model formulation is based on the extension of the bioheat equation, originally proposed by Pennes(1) and later modified by Wissler(2), Stolwijk(3) and Werner and Webb(4). The temporal response of the brain temperature and that of the various body compartments to the cooling of the blood flowing through the common carotid artery is calculated under various scenarios. The effect of the boundary conditions as well as the closure assumptions used in the model, i.e. perfusion rate, metabolism heat production, etc. on the cooling rate of the brain are systematically investigated. (1) Pennes H. H., “Analysis of tissue and arterial blood temperature in the resting forearm.” J. Appl. Physiol. 1: 93-122, 1948. (2) Wissler E. H., “Steady-state temperature distribution in man”, J. Appl. Physiol., 16: 764-740, 1961. (3) Stolwick J. A. J., “Mathematical model of thermoregulation” in “Physiological and behavioral temperature regulation”, edited by J. D. Hardy, A. P. Gagge and A. J. Stolwijk, Charles C. Thomas Publisher, Springfiels, Ill., 703-721, 1971. (4) Werner J., Webb P., “A six-cylinder model of human thermoregulation for general use on personal computers”, Ann. Physiol. Anthrop., 12(3): 123-134, 1993.

  1. Comparative analysis of steady state heat transfer in a TBC and functionally graded air cooled gas turbine blade

    Indian Academy of Sciences (India)

    Nilanjan Coomar; Ravikiran Kadoli

    2010-02-01

    Internal cooling passages and thermal barrier coatings (TBCs) are presently used to control metal temperatures in gas turbine blades. Functionally graded materials (FGMs), which are typically mixtures of ceramic and metal, have been proposed for use in turbine blades because they possess smooth property gradients thereby rendering them more durable under thermal loads. In the present work, a functionally graded model of an air-cooled turbine blade with airfoil geometry conforming to the NACA0012 is developed which is then used in a finite element algorithm to obtain a non-linear steady state solution to the heat equation for the blade under convection and radiation boundary conditions. The effects of external gas temperature, coolant temperature, surface emissivity changes and different average ceramic/metal content of the blade on the temperature distributions are examined. Simulations are also carried out to compare cooling effectiveness of functionally graded blades with that of blades having TBC. The results highlight the effect of including radiation in the simulation and also indicate that external gas temperature influences the blade heat transfer more strongly. It is also seen that graded blades with about 70% ceramic content can deliver better cooling effectiveness than conventional blades with TBC.

  2. Transient heat transfer characteristics of mist cooling from horizontal upward-facing surface. Suihei uemuki heimen kei deno hiteijo mist reikyaku netsu dentatsu tokusei ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Okubo, H.; Nishio, S. (Univ. of Tokyo, Tokyo (Japan). Inst. of Industrial Science)

    1991-07-25

    As mist cooling comprising of cooling heated surface by colliding with a group of pulverized droplet, one of sprayed cooling, is known to show heat transfer feature expressed by letter N curve like boiling one, it represents another complex phenomenone by adding some other new factors such as behavior of the collided particles, effect of air flow and others except boiling phenomenone. On the other hand, it is required to control the cooling ability with high accuracy in the field of heat treatment of steel widely applied such mist cooling. In this paper, an effect of unsteadiness of heat transfer face was examined in a plain system upper-faced holizontally by using the heat transfer face having different thickness. All specimens used in this experiment had 15mm in diameter of the heat transfer face, which were made of silver in seven kinds of thickness, and of SUS and quartz glass in four. Consequently, some informations were obtained that in unsteady region heat transfer coefficients of high temperature region could be well related with heat capacity of the face. 22 refs., 9 figs., 1 tab.

  3. Heat transfer

    CERN Document Server

    Holman, J P

    2010-01-01

    As one of the most popular heat transfer texts, Jack Holman's "Heat Transfer" is noted for its clarity, accessible approach, and inclusion of many examples and problem sets. The new tenth edition retains the straight-forward, to-the-point writing style while covering both analytical and empirical approaches to the subject. Throughout the book, emphasis is placed on physical understanding while, at the same time, relying on meaningful experimental data in those situations that do not permit a simple analytical solution. New examples and templates provide students with updated resources for computer-numerical solutions.

  4. Effect of sintering columns on the heat transfer and flow characteristics of the liquid cooling vapor chambers

    Science.gov (United States)

    Naphon, Paisarn; Wiriyasart, Songkran

    2016-09-01

    The results of the heat and flow characteristics of working fluid inside the vapor chamber with different sintering columns of 20, 81, 225 are presented. The vapor chambers with one inlet port and four outlet ports are tested by using water as coolant. Parametric studies including different heat fluxes, number and size of wick columns, and flow rate of coolants on the cooling performance are considered. A three-dimensional heat and mass transfer model for vapor chamber with wick and without sintering plate and sintering columns are developed. The numerical simulation results show the velocity and pressure distribution of liquid and vapor phases of the working fluid inside the vapor chamber. It is found that the number of wick column have an important influence to the velocity and pressure phenomena of working fluid which results in thermal performance of vapor chamber. Reasonable agreement is obtained from the comparison between the measured data and the predicted results.

  5. Mathematical model on heat transfer of water-cooling steel-stick bottom electrode of DC electric arc furnace

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    For predicting and controlling the melted depth of bottom electrode during the process of steelmaking, the water-cooling steel-stick electrode is taken as an example, to analyze the process of heat transfer, then 3D mathematical model by control capacity method is built. At the same time, the measurement on the melted depth of bottom electrode is conducted which verified the correctness of the built mathematical model. On the base of verification, all kinds of key parameters are calculated through the application and a series of results are simulated. Finally, the optimum parameters are found and the service lifeof bottom electrode is prolonged.

  6. Experimental and numerical study of near bleed hole heat transfer enhancement in internal turbine blade cooling channels

    CSIR Research Space (South Africa)

    Scheepers, G

    2006-01-01

    Full Text Available Conference on Computational and Applied Mechanics SACAM06 Cape Town, 16-18 January 2006 SACAM EXPERIMENTAL AND NUMERICAL STUDY OF NEAR BLEED HOLE HEAT TRANSFER ENHANCEMENT IN INTERNAL TURBINE BLADE COOLING CHANNELS Scheepers G*, Morris RM, Visser JA....5×104, while the hole suction ratio in terms of Reynolds number was varied from 0 to 5. 1. Introduction With the ever increasing demand for higher thermal efficiency, modern jet turbine blades are exposed to temperatures which comprehensively exceed...

  7. Comparison of heat transfer in liquid and slush nitrogen by numerical simulation of cooling rates for French straws used for sperm cryopreservation.

    Science.gov (United States)

    Sansinena, M; Santos, M V; Zaritzky, N; Chirife, J

    2012-05-01

    Slush nitrogen (SN(2)) is a mixture of solid nitrogen and liquid nitrogen, with an average temperature of -207 °C. To investigate whether plunging a French plastic straw (commonly used for sperm cryopreservation) in SN(2) substantially increases cooling rates with respect to liquid nitrogen (LN(2)), a numerical simulation of the heat conduction equation with convective boundary condition was used to predict cooling rates. Calculations performed using heat transfer coefficients in the range of film boiling confirmed the main benefit of plunging a straw in slush over LN(2) did not arise from their temperature difference (-207 vs. -196 °C), but rather from an increase in the external heat transfer coefficient. Numerical simulations using high heat transfer (h) coefficients (assumed to prevail in SN(2)) suggested that plunging in SN(2) would increase cooling rates of French straw. This increase of cooling rates was attributed to a less or null film boiling responsible for low heat transfer coefficients in liquid nitrogen when the straw is placed in the solid-liquid mixture or slush. In addition, predicted cooling rates of French straws in SN(2) tended to level-off for high h values, suggesting heat transfer was dictated by heat conduction within the liquid filled plastic straw.

  8. Mass Transfer Cooling Near The Stagnation Point

    Science.gov (United States)

    Roberts, Leonard

    1959-01-01

    A simplified analysis is made of mass transfer cooling, that is, injection of a foreign gas, near the stagnation point for two-dimensional and axisymmetric bodies. The reduction in heat transfer is given in terms of the properties of the coolant gas and it is shown that the heat transfer may be reduced considerably by the introduction of a gas having appropriate thermal and diffusive properties. The mechanism by which heat transfer is reduced is discussed.

  9. Heat transfer and parametric studies of an encapsulated phase change material based cool thermal energy storage system

    Institute of Scientific and Technical Information of China (English)

    CHERALATHAN M.; VELRAJ R.; RENGANARAYANAN S.

    2006-01-01

    This work investigates the transient behaviour of a phase change material based cool thermal energy storage (CTES)system comprised of a cylindrical storage tank filled with encapsulated phase change materials (PCMs) in spherical container integrated with an ethylene glycol chiller plant. A simulation program was developed to evaluate the temperature histories of the heat transfer fluid (HTF) and the phase change material at any axial location during the charging period. The results of the model were validated by comparison with experimental results of temperature profiles of HTF and PCM. The model was also used to investigate the effect of porosity, Stanton number, Stefan number and Peclet number on CTES system performance. The results showed that increase in porosity contributes to a higher rate of energy storage. However, for a given geometry and heat transfer coefficient, the mass of PCM charged in the unit decreases as the increase in porosity. The St number as well as the Ste number is also influential in the performance of the unit. The model is a convenient and more suitable method to determine the heat transfer characteristics of CTES system. The results reported are much useful for designing CTES system.

  10. Design of conformal cooling for plastic injection moulding by heat transfer simulation

    Directory of Open Access Journals (Sweden)

    Sabrina Marques

    2015-12-01

    Full Text Available The cooling channels of a mold for plastic injection have to be as close as possible to the part geometry in order to ensure fast and homogeneous cooling. However, conventional methods to manufacture cooling channels (drilling can only produce linear holes. Selective laser melting (SLM is an additive manufacturing technique capable to manufacture complex cooling channels (known as conformal cooling. Nevertheless, because of the high costs of SLM the benefits of conformal collings are still not clear. The current work investigates two designs of conformal coolings: i parallel circuit; ii serial circuit. Both coolings are evaluated against to traditional cooling circuits (linear channels by CAE simulation to produce parts of polypropylene. The results show that if the conformal cooling is not properly designed it cannot provide reasonable results. The deformation of the product can be reduced significantly after injection but the cycle time reduced not more than 6%.

  11. Digitized Heat Transfer

    Science.gov (United States)

    Mohseni, Kamran; Young, Patrick

    2007-11-01

    This presentation presents theoretical and numerical results describing digitized heat transfer (DHT), an active thermal management technique for high-power electronics and integrated micro systems. In digitized heat transfer discrete droplets are employed. The internal flow inside a discrete droplet is dominated by internal circulation imposed by the boundaries. This internal circulation imposes a new timescale for recirculating cold liquid from the middle of the droplet to the boundary. This internal circulation produces periodic oscillation in the overall convective heat transfer rate. Numerical simulations are presented for heat transfer in the droplet for both constant temperature and flux boundary conditions. The effectiveness of DHT for managing both localized temperature spikes and steady state cooling is demonstrated, identifying key parameters for optimization of the DHT method.

  12. Study on heat transfer characteristics of the one side-heated vertical channel with inserted porous materials applied as a vessel cooling system

    Directory of Open Access Journals (Sweden)

    Shinji Kuriyama

    2015-08-01

    Full Text Available In the very high temperature reactor (VHTR, which is a next generation nuclear reactor system, ceramics are used as a fuel coating material and graphite is used as a core structural material. Even if a depressurization accident occurs and the reactor power goes up instantly, the temperature of the core will change only slowly. This is because the thermal capacity of the core is so high. Therefore, the VHTR system can passively remove the decay heat of the core by natural convection and radiation from the surface of the reactor pressure vessel. The objectives of this study are to investigate the heat transfer characteristics of natural convection of a one-side heated vertical channel with inserted porous materials of high porosity and also to develop the passive cooling system for the VHTR. An experiment was carried out using a one-side heated vertical rectangular channel. To obtain the heat transfer and fluid flow characteristics of the vertical channel with inserted porous material, we have also carried out a numerical analysis using a commercial Computational Fluid Dynamics (CFD code. This paper describes the thermal performances of the one-side heated vertical rectangular channel with an inserted copper wire of high porosity.

  13. Heat transfer

    CERN Document Server

    Jorge, Kubie; Thomas, Grassie

    2012-01-01

    A core task of engineers is to analyse energy related problems. The analytical treatment is usually based on principles of thermodynamics, fluid mechanics and heat transfer, but is increasingly being handled computationally.This unique resource presents a practical textbook, written for both undergraduates and professionals, with a series of over 60 computer workbooks on an accompanying CD.The book emphasizes how complex problems can be deconstructed into a series of simple steps. All thermophysical property computations are illustrated using diagrams within text and on the compani

  14. NUMERICAL INVESTIGATION OF THE ADVERSE EFFECT OF WIND ON THE HEAT TRANSFER PERFORMANCE OF TWO NATURAL DRAFT COOLING TOWERS IN TANDEM ARRANGEMENT

    Institute of Scientific and Technical Information of China (English)

    符松; 翟志强

    2001-01-01

    This article reports the findings on the adverse effect of the crosswind on the performance of natural draft cooling towers through numerical computation with the k-ε eddy-viscosity turbulence model. It is observed here that the cause of the adverse effect of the crosswind on the cooling towers can be attributed to the around flow effect which destroys the radial inflow into the cooling towers when the wind is absent. Hence, a significant deterioration in the heat transfer from the heat exchangers at lateral sides occurs.

  15. Mathematical Model on heat transfer of water—cooling steel—stick bottom electrode of DC electric arc furnace

    Institute of Scientific and Technical Information of China (English)

    HaiXu; XiaoLiu; 等

    2002-01-01

    For predicting and controlling the melted depth of bottom electrode during the process of steelmaking,the water-cooling steel stick electrode is taken as an example.to analyze the process of heat transfer,then 3D mathematical model by control capacity method is built.At the same time,the measurement on the melted depth of bottom electrode is conducted which verified the correctness of the built mathematical model.On the base of verification,all kinds of key parameters are calculated through the application and a series of results are simulated.Finally,the optimum parameters are found and the service life of bottom electrode is prolonged.

  16. Assessment of external heat transfer coefficient during oocyte vitrification in liquid and slush nitrogen using numerical simulations to determine cooling rates.

    Science.gov (United States)

    Santos, M V; Sansinena, M; Zaritzky, N; Chirife, J

    2012-01-01

    In oocyte vitrification, plunging directly into liquid nitrogen favor film boiling and strong nitrogen vaporization. A survey of literature values of heat transfer coefficients (h) for film boiling of small metal objects with different geometries plunged in liquid nitrogen revealed values between 125 to 1000 W per per square m per K. These h values were used in a numerical simulation of cooling rates of two oocyte vitrification devices (open-pulled straw and Cryotop), plunged in liquid and slush nitrogen conditions. Heat conduction equation with convective boundary condition was considered a linear mathematical problem and was solved using the finite element method applying the variational formulation. COMSOL Multiphysics was used to simulate the cooling process of the systems. Predicted cooling rates for OPS and Cryotop when cooled at -196 degree C (liquid nitrogen) or -207 degree C (average for slush nitrogen) for heat transfer coefficients estimated to be representative of film boiling, indicated lowering the cooling temperature produces only a maximum 10 percent increase in cooling rates; confirming the main benefit of plunging in slush over liquid nitrogen does not arise from their temperature difference. Numerical simulations also demonstrated that a hypothetical four-fold increase in the cooling rate of vitrification devices when plunging in slush nitrogen would be explained by an increase in heat transfer coefficient. This improvement in heat transfer (i.e., high cooling rates) in slush nitrogen is attributed to less or null film boiling when a sample is placed in slush (mixture of liquid and solid nitrogen) because it first melts the solid nitrogen before causing the liquid to boil and form a film.

  17. Solar heating and cooling.

    Science.gov (United States)

    Duffie, J A; Beckman, W A

    1976-01-16

    We have adequate theory and engineering capability to design, install, and use equipment for solar space and water heating. Energy can be delivered at costs that are competitive now with such high-cost energy sources as much fuel-generated, electrical resistance heating. The technology of heating is being improved through collector developments, improved materials, and studies of new ways to carry out the heating processes. Solar cooling is still in the experimental stage. Relatively few experiments have yielded information on solar operation of absorption coolers, on use of night sky radiation in locations with clear skies, on the combination of a solar-operated Rankine engine and a compression cooler, and on open cycle, humidification-dehumidification systems. Many more possibilities for exploration exist. Solar cooling may benefit from collector developments that permit energy delivery at higher temperatures and thus solar operation of additional kinds of cycles. Improved solar cooling capability can open up new applications of solar energy, particularly for larger buildings, and can result in markets for retrofitting existing buildings. Solar energy for buildings can, in the next decade, make a significant contribution to the national energy economy and to the pocketbooks of many individual users. very large-aggregate enterprises in manufacture, sale, and installation of solar energy equipment can result, which can involve a spectrum of large and small businesses. In our view, the technology is here or will soon be at hand; thus the basic decisions as to whether the United States uses this resource will be political in nature.

  18. Heat transfer through a horizontal annular layer of magnetic fluid during the cooling of cylindrical current conductors

    Energy Technology Data Exchange (ETDEWEB)

    Polevikov, V.K.; Fertman, V.E.

    1977-01-01

    The results of a numerical study are presented for stationary natural convection in an annular magnetic fluid layer which cools a horizontal cylindrical current conductor. The system of two-dimensional hydrodynamics equations was solved in a non-inductive approximation by the finite differences method. A monotonic conservative differential system of second order accuracy was used. The studies were made in the ranges: 10 < or = to Pr < or = to 10/sup 4/, 0 < or = to Ra < or = to 10/sup 6/, 0 < or = to Ra/sub m/ < or = to 10/sup 8/, 1.5 < or = to r/sub 2//r/sub 1/ < or = to 5 (Pr--Prandtl number; Ra--Rayleigh number; Ra/sub m/--parameter of magnetic convection mechanism; r/sub 2//r/sub 1/--radius ratio of coaxial cylinders). The developmental characteristics of thermoconvective structures, local and integral thermal currents in an annular layer during a change in specific parameters are discussed. Critical formulae are constructed which describe convective heat transfer when Ra/sub m/ much greater than Ra and Ra/sub m/ much less than Ra in which case a good agreement is obtained with known experimental data. The results of the study may be used in devising cooling systems for electrical cables. 5 illustrations, 11 references.

  19. Numerical Simulation of Three-dimensional Heat and Mass Transfer in Spray Cooling of Converter Gas in a Venturi Scrubber

    Institute of Scientific and Technical Information of China (English)

    LU Tao; WANG Kuisheng

    2009-01-01

    In order to predict the pressure drop, collection efficiency, velocity, temperature and mole fraction of vapor in an industrial venturi scrubber with water spraying for converter gas cooling, a three-dimensional model of heat and mass transfer with phase change is established. The gas flow and liquid droplets are treated as a continuous phase with a Eulerian approach and as a discrete phase with a Lagrangian approach, respectively. The coupled problem of heat, force, and mass transfers between gas flow and liquid droplets is solved by a commercial computational fluid dynamics(CFD) package, FLUENT. The numerical results show that the water injections have an important influence on the distributions of pressure, velocity, temperature, and mole fraction of vapor, especially for the spraying region in the throat. In the spraying region, the pressure drop is higher and the velocity is lower than in other regions due to the gas-droplet drag, while the temperature is lower because the droplet absorbs large amounts of heat from the high temperature gas and the mole fraction of vapor is higher due to the phase change of the liquid droplet. A number of cases with different water-to-gas volume flow ratios and baffle openings were simulated. The dependence of pressure drop, velocity, temperature, mole fraction of vapor, and collection efficiency on both the water-to-gas volume flow ratio and baffle opening are analyzed. The good agreements between simulation results and experiment data of pressure drop, temperature, and collection efficiency validate the model. The model should facilitate optimization of the venturi scrubber design in order to give better performance with lower pressure drops and higher collection efficiency.

  20. Blade-to-coolant heat-transfer results and operating data from a natural-convection water-cooled single-stage turbine

    Science.gov (United States)

    Diaguila, Anthony J; Freche, John C

    1951-01-01

    Blade-to-coolant heat-transfer data and operating data were obtained with a natural-convection water-cooled turbine over range of turbine speeds and inlet-gas temperatures. The convective coefficients were correlated by the general relation for natural-convection heat transfer. The turbine data were displaced from a theoretical equation for natural convection heat transfer in the turbulent region and from natural-convection data obtained with vertical cylinders and plates; possible disruption of natural convection circulation within the blade coolant passages was thus indicated. Comparison of non dimensional temperature-ratio parameters for the blade leading edge, midchord, and trailing edge indicated that the blade cooling effectiveness is greatest at the midchord and least at the trailing edge.

  1. Evaporative CO2 heat transfer measurements for cooling systems of particle physics detectors

    NARCIS (Netherlands)

    Colijn, A.P.; Verlaat, B.

    2010-01-01

    A major challenge in particle physics detectors is to transport the heat developed in their electronics to the outside world. Particle detectors require a minimum of material in order not to disturb accurate measurements of particle trajectories. CO2 has superior behavior in small diameter - low mat

  2. Heat and mass transfer during cooling and storage of agricultural products as influenced by natural convection

    OpenAIRE

    Beukema, K.J.

    1980-01-01

    Three different models of bulk-stored agricultural products with air flow through the bulk, predicting the temperature profiles or the velocity of natural convection, are developed. The temperature distribution in a cylindrical container with insulated walls and open top and bottom, filled with heat-generating model material is studied experimentally, used to calculate the velocity of natural convection and compared with model predictions. A two-dimensional two-phase model of temper...

  3. A brief review on mixed convection heat transfer in channel flow with vortex generator for electronic chip cooling

    Directory of Open Access Journals (Sweden)

    S K Mandal

    2016-06-01

    Full Text Available In an effort to increase processor speeds, 3D IC architecture is being aggressively pursued by researchers and chip manufacturers. This architecture allows extremely high level of integration with enhanced electrical performance and expanded functionality, and facilitates realization of VLSI and ULSI technologies. However, utilizing the third dimension to provide additional device layers poses thermal challenges due to the increased heat dissipation and complex electrical interconnects among different layers. The conflicting needs of the cooling system requiring larger flow passage dimensions to limit the pressure drop, and the IC architecture necessitating short interconnect distances to reduce signal latency warrant paradigm shifts in both of their design approach. Additional considerations include the effects due to temperature non-uniformity, localized hot spots, complex fluidic connections, and mechanical design. This paper reviews the advances in electronic chip cooling in the last decade and provides a vision for code signing integrated cooling systems. For various heat fluxes on each side of a chip acting as discrete heat source, the current single-phase cooling technology is projected to provide adequate cooling, albeit with high pressure drops. Effectively mitigating the high temperatures surrounding local hot spots remains a challenging issue. Various forms of tabulators above the chips, different geometric arrangements of the chips positioned top and bottom wall of the duct serves very well in the heat augmentation technique with better performance

  4. Determination of blade-to-coolant heat-transfer coefficients on a forced-convection, water-cooled, single-stage turbine

    Science.gov (United States)

    Freche, John C; Schum, Eugene F

    1951-01-01

    Blade-to-coolant convective heat-transfer coefficients were obtained on a forced-convection water-cooled single-stage turbine over a large laminar flow range and over a portion of the transition range between laminar and turbulent flow. The convective coefficients were correlated by the general relation for forced-convection heat transfer with laminar flow. Natural-convection heat transfer was negligible for this turbine over the Grashof number range investigated. Comparison of turbine data with stationary tube data for the laminar flow of heated liquids showed good agreement. Calculated average midspan blade temperatures using theoretical gas-to-blade coefficients and blade-to-coolant coefficients from stationary-tube data resulted in close agreement with experimental data.

  5. Development of an integrated model for heat transfer and dynamic growth of Clostridium perfringens during the cooling of cooked boneless ham.

    Science.gov (United States)

    Amézquita, A; Weller, C L; Wang, L; Thippareddi, H; Burson, D E

    2005-05-25

    Numerous small meat processors in the United States have difficulties complying with the stabilization performance standards for preventing growth of Clostridium perfringens by 1 log10 cycle during cooling of ready-to-eat (RTE) products. These standards were established by the Food Safety and Inspection Service (FSIS) of the US Department of Agriculture in 1999. In recent years, several attempts have been made to develop predictive models for growth of C. perfringens within the range of cooling temperatures included in the FSIS standards. Those studies mainly focused on microbiological aspects, using hypothesized cooling rates. Conversely, studies dealing with heat transfer models to predict cooling rates in meat products do not address microbial growth. Integration of heat transfer relationships with C. perfringens growth relationships during cooling of meat products has been very limited. Therefore, a computer simulation scheme was developed to analyze heat transfer phenomena and temperature-dependent C. perfringens growth during cooling of cooked boneless cured ham. The temperature history of ham was predicted using a finite element heat diffusion model. Validation of heat transfer predictions used experimental data collected in commercial meat-processing facilities. For C. perfringens growth, a dynamic model was developed using Baranyi's nonautonomous differential equation. The bacterium's growth model was integrated into the computer program using predicted temperature histories as input values. For cooling cooked hams from 66.6 degrees C to 4.4 degrees C using forced air, the maximum deviation between predicted and experimental core temperature data was 2.54 degrees C. Predicted C. perfringens growth curves obtained from dynamic modeling showed good agreement with validated results for three different cooling scenarios. Mean absolute values of relative errors were below 6%, and deviations between predicted and experimental cell counts were within 0.37 log10

  6. Evaluation of a method for heat transfer measurements and thermal visualization using a composite of a heater element and liquid crystals. [thermal performance of turbine blade cooling configurations

    Science.gov (United States)

    Hippensteele, S. A.; Russell, L. M.; Stepka, F. S.

    1981-01-01

    Commercially available elements of a composite consisting of a plastic sheet coated with liquid crystal, another sheet with a thin layer of a conducting material (gold or carbon), and copper bus bar strips were evaluated and found to provide a simple, convenient, accurate, and low-cost measuring device for use in heat transfer research. The particular feature of the composite is its ability to obtain local heat transfer coefficients and isotherm patterns that provide visual evaluation of the thermal performances of turbine blade cooling configurations. Examples of the use of the composite are presented.

  7. Transient heat transfer behavior of water spray evaporative cooling on a stainless steel cylinder with structured surface for safety design application in high temperature scenario

    Science.gov (United States)

    Aamir, Muhammad; Liao, Qiang; Hong, Wang; Xun, Zhu; Song, Sihong; Sajid, Muhammad

    2017-02-01

    High heat transfer performance of spray cooling on structured surface might be an additional measure to increase the safety of an installation against any threat caused by rapid increase in the temperature. The purpose of present experimental study is to explore heat transfer performance of structured surface under different spray conditions and surface temperatures. Two cylindrical stainless steel samples were used, one with pyramid pins structured surface and other with smooth surface. Surface heat flux of 3.60, 3.46, 3.93 and 4.91 MW/m2 are estimated for sample initial average temperature of 600, 700, 800 and 900 °C, respectively for an inlet pressure of 1.0 MPa. A maximum cooling rate of 507 °C/s was estimated for an inlet pressure of 0.7 MPa at 900 °C for structured surface while for smooth surface maximum cooling rate of 356 °C/s was attained at 1.0 MPa for 700 °C. Structured surface performed better to exchange heat during spray cooling at initial sample temperature of 900 °C with a relative increase in surface heat flux by factor of 1.9, 1.56, 1.66 and 1.74 relative to smooth surface, for inlet pressure of 0.4, 0.7, 1.0 and 1.3 MPa, respectively. For smooth surface, a decreasing trend in estimated heat flux is observed, when initial sample temperature was increased from 600 to 900 °C. Temperature-based function specification method was utilized to estimate surface heat flux and surface temperature. Limited published work is available about the application of structured surface spray cooling techniques for safety of stainless steel structures at very high temperature scenario such as nuclear safety vessel and liquid natural gas storage tanks.

  8. Transient heat transfer behavior of water spray evaporative cooling on a stainless steel cylinder with structured surface for safety design application in high temperature scenario

    Science.gov (United States)

    Aamir, Muhammad; Liao, Qiang; Hong, Wang; Xun, Zhu; Song, Sihong; Sajid, Muhammad

    2016-05-01

    High heat transfer performance of spray cooling on structured surface might be an additional measure to increase the safety of an installation against any threat caused by rapid increase in the temperature. The purpose of present experimental study is to explore heat transfer performance of structured surface under different spray conditions and surface temperatures. Two cylindrical stainless steel samples were used, one with pyramid pins structured surface and other with smooth surface. Surface heat flux of 3.60, 3.46, 3.93 and 4.91 MW/m2 are estimated for sample initial average temperature of 600, 700, 800 and 900 °C, respectively for an inlet pressure of 1.0 MPa. A maximum cooling rate of 507 °C/s was estimated for an inlet pressure of 0.7 MPa at 900 °C for structured surface while for smooth surface maximum cooling rate of 356 °C/s was attained at 1.0 MPa for 700 °C. Structured surface performed better to exchange heat during spray cooling at initial sample temperature of 900 °C with a relative increase in surface heat flux by factor of 1.9, 1.56, 1.66 and 1.74 relative to smooth surface, for inlet pressure of 0.4, 0.7, 1.0 and 1.3 MPa, respectively. For smooth surface, a decreasing trend in estimated heat flux is observed, when initial sample temperature was increased from 600 to 900 °C. Temperature-based function specification method was utilized to estimate surface heat flux and surface temperature. Limited published work is available about the application of structured surface spray cooling techniques for safety of stainless steel structures at very high temperature scenario such as nuclear safety vessel and liquid natural gas storage tanks.

  9. Conjugate Heat transfer Analysis of helical fins with airfoil crosssection and its comparison with existing circular fin design for air cooled engines employing constant rectangular cross-section

    Directory of Open Access Journals (Sweden)

    Ashwin Shridhar

    2015-06-01

    Full Text Available Air Cooled Engines have been used in a variety of applications, ranging from airplanes to motorbikes and even stationary or portable engines. Since modern automobiles and airplanes use engines delivering more power, they have to be cooled more efficiently due to which a more complex water cooling system is used for cooling engines with large displacements. Hence air cooling is becoming a thing of the past, especially in the aviation sector due to the advent of more efficient gas turbine engines. However air cooled internal combustion engines are still being used in a wide variety of two-wheelers ranging from small single cylinder engines to heavy duty liter class V-twins and Inline fours, due to the non-practicalities associated with the installment of a bulky water cooling system in two-wheelers. So one can ascertain that there is a scope for improving the efficiency of air cooled engines even further. The objective of this paper is to analyze currently existing fin design employed in most of the air cooled engines and improve it by changing the cross-section to a streamlined one and also making the fins in a helical orientation as opposed to the regular circular fins employed. Our analysis comprises of a computational fluid dynamics study of both the fin models with identical dimensions and simulated in the same environment using ANSYS FLUENT 15 software and we attempt to compare their performance using the temperature and heat transfer coefficient distribution plots obtained.

  10. Cryogenic heat transfer

    CERN Document Server

    Barron, Randall F

    2016-01-01

    Cryogenic Heat Transfer, Second Edition continues to address specific heat transfer problems that occur in the cryogenic temperature range where there are distinct differences from conventional heat transfer problems. This updated version examines the use of computer-aided design in cryogenic engineering and emphasizes commonly used computer programs to address modern cryogenic heat transfer problems. It introduces additional topics in cryogenic heat transfer that include latent heat expressions; lumped-capacity transient heat transfer; thermal stresses; Laplace transform solutions; oscillating flow heat transfer, and computer-aided heat exchanger design. It also includes new examples and homework problems throughout the book, and provides ample references for further study.

  11. A Computational Fluid Dynamic and Heat Transfer Model for Gaseous Core and Gas Cooled Space Power and Propulsion Reactors

    Science.gov (United States)

    Anghaie, S.; Chen, G.

    1996-01-01

    A computational model based on the axisymmetric, thin-layer Navier-Stokes equations is developed to predict the convective, radiation and conductive heat transfer in high temperature space nuclear reactors. An implicit-explicit, finite volume, MacCormack method in conjunction with the Gauss-Seidel line iteration procedure is utilized to solve the thermal and fluid governing equations. Simulation of coolant and propellant flows in these reactors involves the subsonic and supersonic flows of hydrogen, helium and uranium tetrafluoride under variable boundary conditions. An enthalpy-rebalancing scheme is developed and implemented to enhance and accelerate the rate of convergence when a wall heat flux boundary condition is used. The model also incorporated the Baldwin and Lomax two-layer algebraic turbulence scheme for the calculation of the turbulent kinetic energy and eddy diffusivity of energy. The Rosseland diffusion approximation is used to simulate the radiative energy transfer in the optically thick environment of gas core reactors. The computational model is benchmarked with experimental data on flow separation angle and drag force acting on a suspended sphere in a cylindrical tube. The heat transfer is validated by comparing the computed results with the standard heat transfer correlations predictions. The model is used to simulate flow and heat transfer under a variety of design conditions. The effect of internal heat generation on the heat transfer in the gas core reactors is examined for a variety of power densities, 100 W/cc, 500 W/cc and 1000 W/cc. The maximum temperature, corresponding with the heat generation rates, are 2150 K, 2750 K and 3550 K, respectively. This analysis shows that the maximum temperature is strongly dependent on the value of heat generation rate. It also indicates that a heat generation rate higher than 1000 W/cc is necessary to maintain the gas temperature at about 3500 K, which is typical design temperature required to achieve high

  12. Numerical Investigation of Single Phase Fluid Flow and Heat Transfer In Rectangular Micro Channel Using Nanofluids as A Cooling Liquid

    Directory of Open Access Journals (Sweden)

    Mr. Sanjay V. Barad,

    2014-04-01

    Full Text Available In this paper The Thermal behaviour of Micro channel heat sink were investigated used Al2o3-water base nanoluid. The model have been solved by ANSYS fluent 14.5 solver. The Dimension of each rectangular channel is 215m width, 821m depth and 4.48cm length. The Reynolds number range from 200 to 400 for power input 100 w. The high thermal conductivity of nanoparticles is shown to enhance the single phase heat transfer coefficient, especially for laminar flow. Higher heat transfer coefficient were achieved mostly in entrances region of micro channels. The enhancement was weaker in fully developed region.

  13. Development and assessment of a coupled strategy for conjugate heat transfer with Large Eddy Simulation: Application to a cooled turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Duchaine, F., E-mail: florent.duchaine@cerfacs.f [CERFACS, 42 av. Coriolis, 31 057 Toulouse Cedex 01 (France); Corpron, A.; Pons, L. [Turbomeca (Safran Group), BP17, 64 511 Bordes Cedex (France); Moureau, V. [Turbomeca (Safran Group), BP17, 64 511 Bordes Cedex (France); CORIA, Site universitaire du Madrillet, BP8, 76 801 Saint Etienne du Rouvray Cedex (France); Nicoud, F. [Unviservite Montpellier II, Place Bataillon, 34 095 Montpellier Cedex 5 (France); Poinsot, T. [IMFT, Avenue Camille Soula, 31 400 Toulouse Cedex (France)

    2009-12-15

    Although Large Eddy Simulation (LES) is identified today as the most promising method for turbulent flow problems, few applications of LES coupled to heat transfer solvers in solids have been published. This paper describes a coupling strategy of a LES solver and a heat transfer code within solids on parallel architectures. The numerical methods used in both solvers are briefly recalled before discussing the coupling strategy in terms of physical quantities to exchange (fluxes and temperatures), stability and parallel efficiency. The stability study is performed using an amplification matrix analysis on a one-dimensional case and allows the determination and optimization of coupling parameters. The coupled tool is then applied to a cooled turbine blade model where results demonstrate both the efficiency of the parallel implementation and the quality of the results. Coupled and non-coupled simulations are compared to experimental results and discussed in terms of cooling efficiency and flow structures.

  14. Advances in heat transfer enhancement

    CERN Document Server

    Saha, Sujoy Kumar; Sundén, Bengt; Wu, Zan

    2016-01-01

    This Brief addresses the phenomena of heat transfer enhancement. A companion edition in the SpringerBrief Subseries on Thermal Engineering and Applied Science to three other monographs including “Critical Heat Flux in Flow Boiling in Microchannels,” this volume is idea for professionals, researchers, and graduate students concerned with electronic cooling.

  15. MULTIFUNCTIONAL SOLAR SYSTEMS FOR HEATING AND COOLING

    Directory of Open Access Journals (Sweden)

    Doroshenko A.V.

    2010-12-01

    Full Text Available The basic circuits of multifunctional solar systems of air drainage, heating (hot water supply and heating, cooling and air conditioning are developed on the basis of open absorption cycle with a direct absorbent regeneration. Basic decisions for new generation of gas-liquid solar collectors are developed. Heat-mass-transfer apparatus included in evaporative cooling system, are based on film interaction of flows of gas and liquid and in them, for the creation of nozzle, multi-channel structures from polymeric materials and porous ceramics are used. Preliminary analysis of multifunctional systems possibilities is implemented.

  16. Coeficientes de transferencia de calor experimental para el enfriamiento de licor en intercambiadores de placas//Experimental heat transfer coefficients for the liquor cooling in plate heat exchanger

    Directory of Open Access Journals (Sweden)

    Enrique Torres‐Tamayo

    2014-01-01

    Full Text Available La pérdida de eficiencia del proceso de enfriamiento del licor amoniacal, mediante el uso de intercambiadores de calor de placas, está asociada a imprecisiones en la estimación de los coeficientes de transferencia de calor y la acumulación de incrustaciones en la superficie de intercambio. El objetivo de la investigación es determinar los coeficientes de transferencia de calor y la influencia de lasincrustaciones en la pérdida de eficiencia de la instalación. Mediante un procedimiento iterativo se estableció la ecuación del número de Nusselt y su relación con el número de Reynolds y Prandtl. Se utilizó un diseño experimental multifactorial. Los resultados predicen el conocimiento de los coeficientespara el cálculo del número de Nusselt en ambos fluidos. Los valores de los coeficientes del licor amoniacal son inferiores, ello se debe a la presencia de componentes gaseosos. La ecuación obtenida muestra correspondencia con el modelo de Buonapane, el error comparativo es del 3,55 %.Palabras claves: intercambiador de calor de placas, coeficientes de transferencia de calor, eficiencia térmica.______________________________________________________________________________AbstractThe loss of efficiency of the ammonia liquor cooling process, by means of the plate heat exchanger, is associated to the incorrect estimate of the heat transfer coefficients and the accumulation of inlays in the exchange surface. The objective of the investigation is to determine the transfer coefficients and the influence of the inlays in the efficiency loss of the installation. By means of an iterative procedure was obtained the Nusselt number equation and the relationship with the Reynolds and Prandtl number, for it was used it a design experimental multifactorial. The results predict the knowledge of the coefficients forthe calculation of the Nusselt number for both fluids. The ammonia liquor coefficients values are inferior, due to the presence of gassy

  17. Code-to-code comparison for analysing the steady-state heat transfer and natural circulation in an air-cooled RCCS using GAMMA+ and Flownex

    Energy Technology Data Exchange (ETDEWEB)

    Rousseau, P.G., E-mail: pgr@mtechindustrial.com [School of Mechanical and Nuclear Engineering, North-West University, Private Bag X 6001, Potchefstroom (South Africa); Toit, C.G. du [School of Mechanical and Nuclear Engineering, North-West University, Private Bag X 6001, Potchefstroom (South Africa); Jun, J.S.; Noh, J.M. [Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon (Korea, Republic of)

    2015-09-15

    Highlights: • The GAMMA+ and Flownex codes are used in the analyses of the air-cooled RCCS system. • Radiation heat transfer comprises the bulk of the total rate of heat transfer. • It is possible to obtain reverse flow through the RCCS standpipes. • It has been found that the results obtained with the two codes are in good agreement. • RCCS remain functional for very high blockage ratios thus supporting the safety case. - Abstract: The GAMMA+ and Flownex codes are both based on a one-dimensional flow network modelling approach and both can account for any complex network of different heat transfer phenomena occurring simultaneously. However, there are notable differences in some of the detail modelling aspects, such as the way in which the convection in the reactor cavity is represented. Despite this, it was found in the analyses of the air-cooled RCCS system that the results provided by the two codes compare very well if similar input values are used for the pressure drop coefficients, heat transfer coefficients and view factors. The results show that the radiation heat transfer comprises the bulk of the total rate of heat transfer from the RPV surface. It is also shown that it is possible to obtain a stable and sustainable steady-state operational condition where the flow is in the reverse direction through the RCCS standpipes, resulting in excessively high values for the concrete wall temperature. It is therefore crucial in the design to ensure that such a flow reversal will not occur under any circumstances. In general the good comparison between the two codes provides confidence in the ability of both to correctly solve the fundamental conservation and heat transfer relations in an integrated manner for the complete RCCS system. Provided that appropriate input values are available, these codes can therefore be used effectively to evaluate the integrated performance of the system under various operating conditions. It is shown here that the RCCS

  18. Standard Practices for Simulated Service Testing for Corrosion of Metallic Containment Materials for Use With Heat-Transfer Fluids in Solar Heating and Cooling Systems

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1980-01-01

    1.1 These practices cover test procedures simulating field service for evaluating the performance under corrosive conditions of metallic containment materials in solar heating and cooling systems. All test results relate to the performance of the metallic containment material only as a part of a metal/fluid pair. Performance in these test procedures, taken by itself, does not necessarily constitute an adequate basis for acceptance or rejection of a particular metal/fluid pair in solar heating and cooling systems, either in general or in a particular design. 1.2 These practices describe test procedures used to evaluate the resistance to deterioration of metallic containment materials in the several conditions that may occur in operation of solar heating and cooling systems. These conditions include: (1) operating full flow; (2) stagnant empty vented; (3) stagnant, closed to atmosphere, non-draindown; and (4) stagnant, closed to atmosphere, draindown. 1.3 The recommended practices cover the following three te...

  19. Enhanced heat transfer using nanofluids

    Science.gov (United States)

    Choi, Stephen U. S.; Eastman, Jeffrey A.

    2001-01-01

    This invention is directed to a method of and apparatus for enhancing heat transfer in fluids such as deionized water. ethylene glycol, or oil by dispersing nanocrystalline particles of substances such as copper, copper oxide, aluminum oxide, or the like in the fluids. Nanocrystalline particles are produced and dispersed in the fluid by heating the substance to be dispersed in a vacuum while passing a thin film of the fluid near the heated substance. The fluid is cooled to control its vapor pressure.

  20. Correlation Equations of Heat Transfer in Nanofluid Al2O3-Water as Cooling Fluid in a Rectangular Sub Channel Based CFD Code

    Directory of Open Access Journals (Sweden)

    Anwar Ilmar Ramadhan

    2015-03-01

    Full Text Available Safety is a major concern in the design, operation and development of a nuclear reactor. One aspect of nuclear reactor safety factor is thermal-hydraulics aspect. In a PWR-type nuclear power plant has been used lighter fluid coolant is water or H2O. In this research, using nanofluid Al2O3-Water with volume fraction of (1%, (2% and also (3%, used as a cooling fluid in a nuclear reactor core with sub channel PWR fuel element rectangular arrangement. This research was carried out modeling of fuel elements are arranged rectangular, then performed numerical simulations using Computational Fluid Dynamics (CFD code. In order to obtain the characteristic pattern of flow velocity of each fluid, the fluid temperature distribution along the cylinder wall temperature distribution of the fuel element. Then analyzed the heat transfer in a nuclear reactor core with sub channel PWR fuel element rectangular arrangement, including heat transfer coefficient, Nusselt number (Nu, as well as heat transfer correlations. Heat transfer correlation for nanofluid Al2O3-Water (1%, (2% and also (3% proved to core of PWR nuclear reactor fuel element sub channel rectangular arrangement with the Reynolds number (Re is stretched, namely: 404 096 heat flux is 2600 W / m2, and the composition ratio (pitch / diameter 1.33.

  1. Introduction to heat transfer

    CERN Document Server

    SUNDÉN, B

    2012-01-01

    Presenting the basic mechanisms for transfer of heat, Introduction to Heat Transfer gives a deeper and more comprehensive view than existing titles on the subject. Derivation and presentation of analytical and empirical methods are provided for calculation of heat transfer rates and temperature fields as well as pressure drop. The book covers thermal conduction, forced and natural laminar and turbulent convective heat transfer, thermal radiation including participating media, condensation, evaporation and heat exchangers.

  2. Optimization of convective heat transfer coefficient in water jet cooled mirror%射流式水冷镜对流换热系数的优化

    Institute of Scientific and Technical Information of China (English)

    李斌; 焦路光; 刘亮; 李兰; 周琼; 袁圣付; 刘文广

    2011-01-01

    介绍了射流水冷技术并将其应用到高能激光器反射镜的冷却中,设计了射流式水冷镜.采用计算流体力学的方法,利用通用有限元软件ANSYS的流体分析模块FLOTRAN对单孔内射流进行了数值模拟,详细讨论了各孔参数对换热性能的影响.实现了孔参数的优化.结果表明:在水冷镜中采用射流技术可以获得很好的对流换热效果,换热系数可达100 KW/(m·K)以上,且具有结构简单、可控性强等特点.%The jet cooling technology was introduced and used in the cooling of high power laser mirror, then the water jet cooled mirror was designed.Computational fluid dynamics method was adopted to simulate the jet in a hole by the fluid analysis module FLOTRAN of the finite element analysis software ANSYS, then the influence on the capability of heat transfer of the parameters of the hole was discussed and optimization of the parameters was achieved.The results show that great capability of heat transfer can be achieved by using the jet cooling technology, with simple structure and good controllability, and the heat transfer coefficient can be higher than 100 kW/(m2 · K).

  3. Fluid-cooled heat sink for use in cooling various devices

    Energy Technology Data Exchange (ETDEWEB)

    Bharathan, Desikan; Bennion, Kevin; Kelly, Kenneth; Narumanchi, Sreekant

    2017-09-12

    The disclosure provides a fluid-cooled heat sink having a heat transfer base, a shroud, and a plurality of heat transfer fins in thermal communication with the heat transfer base and the shroud, where the heat transfer base, heat transfer fins, and the shroud form a central fluid channel through which a forced or free cooling fluid may flow. The heat transfer pins are arranged around the central fluid channel with a flow space provided between adjacent pins, allowing for some portion of the central fluid channel flow to divert through the flow space. The arrangement reduces the pressure drop of the flow through the fins, optimizes average heat transfer coefficients, reduces contact and fin-pin resistances, and reduces the physical footprint of the heat sink in an operating environment.

  4. Numerical studies on the heat transfer and friction characteristics of the first wall inserted with the screw blade for water cooled ceramic breeder blanket of CFETR

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Kecheng [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); University of Science and Technology of China, Hefei, Anhui 230037 (China); Ma, Xuebin; Cheng, Xiaoman [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Liu, Songlin, E-mail: slliu@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

    2016-03-15

    Highlights: • Enhanced heat transfer and friction characteristics of the FW inserted with screw blade is investigated. • The screw blade structure optimization was done on the screw pitch and diameter. • Decreasing screw pitch and increasing screw diameter could further enhance heat transfer accompanied with increasing flow resistance. • Evaluate the overall enhanced heat performance by using the PEC value. - Abstract: The Water Cooled Ceramic Breeder (WCCB) blanket based on Pressurized Water Reactor (PWR) condition is one of the blanket candidates for Chinese Fusion Engineering Test Reactor (CFETR). The first wall (FW) which plays an important part in the blanket design must remove the high heat flux radiated from plasma and nuclear heat deposition on the structure in any operating conditions. In this paper, the characteristics of enhanced heat transfer and friction for the FW with the inserted screw blade are studied by the numerical method. After the comparison between the numerical and experimental results, the standard k–ε turbulent model is selected to do the numerical calculation. The numerical results show that the peak temperature of RAFM steel could be reduced by decreasing screw pitch or increasing screw diameter, while accompanied with ascending flow resistance. Besides, among all of the chosen calculation cases compared with the smooth channel, the maximum value of temperature reduction is 10 °C under the conditions of heat flux of 0.5 MW/m{sup 2} as well as screw pitch of 18 mm and screw diameter of 6 mm. The maximum increment ratio of the friction factor is 257% under the conditions of screw pitch of 10 mm and screw diameter of 4 mm. Furthermore, screw blade of 74 mm pitch and 4 mm diameter presents the highest overall performance evaluation criterion (PEC) value of 0.93 under Reynolds number of 270 000 conditions, and shows the best overall heat transfer enhancement performance.

  5. An experimental investigation of supercritical heat transfer in a three-rod bundle equipped with wire-wrap and grid spacers and cooled by carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Eter, Ahmad, E-mail: eng.eter@yahoo.com; Groeneveld, Dé, E-mail: degroeneveld@gmail.com; Tavoularis, Stavros, E-mail: stavros.tavoularis@uottawa.ca

    2016-07-15

    Highlights: • Heat transfer at supercritical pressures was studied experimentally in a three-rod bundle equipped with wire-wrap spacers or grid spacers. • Heat transfer deterioration occurred near the heated inlet under certain conditions. • Normal heat transfer was generally comparable to that in a tube and the predictions of a correlation. - Abstract: Heat transfer measurements in a three-rod bundle equipped with wire-wrap and grid spacers were obtained at supercritical pressures in the Supercritical University of Ottawa Loop (SCUOL). The tests were performed using carbon dioxide, as a surrogate fluid for water, flowing upwards for wide ranges of conditions, including conditions equivalent to the nominal and near-normal operating conditions of the proposed Canadian Super-Critical Water-Cooled Reactor. The test section contained three heated rods and three unheated rod segments with an outer diameter of 10 mm and a pitch-to-diameter ratio of 1.14; the heated length was 1500 mm. Detailed surface temperature measurements along and around the three heated rods were collected using internally traversed thermocouples. The following ranges of test conditions were covered, with equivalent water conditions given inside parentheses: pressure from 6.6 to 8.36 MPa (19.7–25 MPa); inlet temperature from 11 to 30 °C (330–371 °C); mass flux from 200 to 1175 kg m{sup −2} s{sup −1} (340–1822 kg m{sup −2} s{sup −1}); and wall heat flux from 1 to 175 kW m{sup −2} (11–1847 kW m{sup −2}). For one set of tests, the heated rods were fitted with a 1.3 mm OD wire wrap, having an axial pitch of 200 mm along the entire heated length; for a second set, the heated rods were fitted with grid spacers having a 5.3% flow blockage and located at 500 mm axial intervals. The effects of spacer configuration on heat transfer at supercritical pressures were documented and analyzed. The observed experimental trends were compared to those obtained in a experiment in a heated

  6. Convective heat transfer

    CERN Document Server

    Kakac, Sadik; Pramuanjaroenkij, Anchasa

    2014-01-01

    Intended for readers who have taken a basic heat transfer course and have a basic knowledge of thermodynamics, heat transfer, fluid mechanics, and differential equations, Convective Heat Transfer, Third Edition provides an overview of phenomenological convective heat transfer. This book combines applications of engineering with the basic concepts of convection. It offers a clear and balanced presentation of essential topics using both traditional and numerical methods. The text addresses emerging science and technology matters, and highlights biomedical applications and energy technologies. What’s New in the Third Edition: Includes updated chapters and two new chapters on heat transfer in microchannels and heat transfer with nanofluids Expands problem sets and introduces new correlations and solved examples Provides more coverage of numerical/computer methods The third edition details the new research areas of heat transfer in microchannels and the enhancement of convective heat transfer with nanofluids....

  7. Heat Transfer Analysis of Fin Tube

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Woo-Jin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Choi, Cheng-Ryul [ELSOLTEC Co., Yongin (Korea, Republic of)

    2015-10-15

    This paper describes a preliminary numerical analysis of fin tube used for a heat exchanger of the air-water cooling system. The internal flow in a fin tube is steam and the external of the fin is cooled by air. Cooling system in a nuclear power plant can be divided into two categories; 1) active pump driven system powered by alternating current and 2) passive cooling system drived by natural circulation phenomena. After the accident in Hukushima Nuclear Power Plants, the importance of the passive cooling system that can provide a long-term cooling of reactor decay heat during station blackout condition is emphasized. However, the effectiveness of passive cooling system based on cooling water is limited by the capacity of water storage tank. To overcome the limit due to the exhaustion of the cooling water, an natural convection air cooling system is proposed. As the air operated cooling system utilizes natural circulation phenomena of air, it does not require cooling water. However, the heat transfer area of the air operated cooling system should be increased much as the heat removal capacity per unit area is much lower than that of water cooling system. The air-water combined cooling system can resolve this excess increase of the heat transfer area in the air operated cooling system. This air-water cooling system can be also used in the passive containment cooling system. The effect of design parameters such as fin tube arrangement, the fin height, and pitch has been analyzed and the chimney effect on the simulation of heat transfer in a heat exchanger is evaluated. The internal flows in a fin tube heat exchanger for natural circulation flow condition and forced convection (suction) condition were investigated.

  8. Multi-flow-field heat transfer parameters optimization on first wall of dual-cooled lithium lead blanket for FDS-II

    Energy Technology Data Exchange (ETDEWEB)

    Wang Weihua; Liu Songlin; Bai Yunqing; Chen Hongli; Wu Yican [Chinese Academy of Sciences, Anhui (China). Inst. of Plasma Physics

    2007-07-01

    The dual-cooled lithium lead (DLL) blanket, which is one of the most important parts of the fusion power reactor FDS-II, has been designed. Reduced activation ferritic/martensitic (e.g. China low activate martensitic CLAM) steel is selected as structural material and helium gas is used to cool the main structure and the self-cooled eutectic LiPb alloy serves both as breeder material and coolant. To decrease magnetohydrodynamic pressure drop and increase output temperature of lithium lead, insulating coating and flow channel inserts have been selected and assessed. The first wall (FW) as the key component of the DLL blanket must withstand and remove the heat flux from the plasma chamber and high power density LiPb Breeding zone. Consequently, the unique design of the blanket (e.g. multi-flow field and dual coolant) results in the complicated thermal-hydraulic characteristics like the coupling of multi-field. Under the limit of temperature 550 C and stress 3Sm of the CLAM steel structural material, Multiflow- field Heat transfer parameters of FW are studied by the computational fluid dynamics FLUENT code and finite element ANSYS code. Heat flux distribution, temperature field, heat transfer coefficients between liquid LiPb and RAFM steel are obtained and optimized accordingly while considering the helium gas flow velocity 20 m/s{proportional_to}120 m/s, heat flux 0.1MW/m{sup 2}{proportional_to}0.7MW/m{sup 2} from the plasma and LiPb Breeding zone. The results can benefit the thermal-hydraulic parameters selection and optimization of the FW. (orig.)

  9. CHARACTERIZATION OF CATALYTIC COMBUSTOR TURBULENCE AND ITS INFLUENCE ON VANE AND ENDWALL HEAT TRANSFER AND ENDWALL FILM COOLING

    Energy Technology Data Exchange (ETDEWEB)

    Forrest E. Ames

    2002-10-01

    Endwall heat transfer distributions taken in a large-scale low speed linear cascade facility are documented for mock catalytic and dry low NOx (DLN) combustion systems. Inlet turbulence levels range from about 1.0 percent for the mock Catalytic combustor condition to 14 percent for the mock dry low NOx combustor system. Stanton number contours are presented at both turbulence conditions for Reynolds numbers based on true chord length and exit conditions ranging from 500,000 to 2,000,000. Catalytic combustor endwall heat transfer shows the influence of the complex three-dimensional flow field, while the effects of individual vortex systems are less evident for the mock dry low NOx cases. Turbulence scales have been documented for both cases. Inlet boundary layers are relatively thin for the mock catalytic combustor case while inlet flow approximates a channel flow with high turbulence for the mock DLN combustor case. Inlet boundary layer parameters are presented across the inlet passage for the three Reynolds numbers and both the mock catalytic and DLN combustor inlet cases. Both midspan and 95 percent span pressure contours are included. This research provides a well-documented database taken across a range of Reynolds numbers and turbulence conditions for assessment of endwall heat transfer predictive capabilities.

  10. Evaporation of Droplets in Plasma Spray-Physical Vapor Deposition Based on Energy Compensation Between Self-Cooling and Plasma Heat Transfer

    Science.gov (United States)

    Liu, Mei-Jun; Zhang, Meng; Zhang, Qiang; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2017-08-01

    In the plasma spray-physical vapor deposition process (PS-PVD), there is no obvious heating to the feedstock powders due to the free molecular flow condition of the open plasma jet. However, this is in contrast to recent experiments in which the molten droplets are transformed into vapor atoms in the open plasma jet. In this work, to better understand the heating process of feedstock powders in the open plasma jet of PS-PVD, an evaporation model of molten ZrO2 is established by examining the heat and mass transfer process of molten ZrO2. The results reveal that the heat flux in PS-PVD open plasma jet (about 106 W/m2) is smaller than that in the plasma torch nozzle (about 108 W/m2). However, the flying distance of molten ZrO2 in the open plasma jet is much longer than that in the plasma torch nozzle, so the heating in the open plasma jet cannot be ignored. The results of the evaporation model show that the molten ZrO2 can be partly evaporated by self-cooling, whereas the molten ZrO2 with a diameter heat transfer.

  11. Utilization of heat pipes for transfer heat from the flue gas into the heat transfer medium

    Directory of Open Access Journals (Sweden)

    Lenhard Richard

    2014-03-01

    Full Text Available The contribution is listed possible application of heat pipes in systems for obtaining heat from flue gas of small heat sources. It is also stated in the contribution design an experimental device on which to study the impact of fill (the quantity, type of load at various temperature parameters (temperature heating and cooling thermal power transferred to the heat pipe. Is listed measurement methodology using heat pipes designed experimental facility, measurement results and analysis of the results obtained.

  12. Heat Transfer and Observation of Droplet-Surface Interactions During Air-Mist Cooling at CSP Secondary System Temperatures

    Science.gov (United States)

    Huerta L., Mario E.; Mejía G., M. Esther; Castillejos E., A. Humberto

    2016-04-01

    Air-mists are key elements in the secondary cooling of modern thin steel slab continuous casters. The selection of water, W, and air, A, flow rates, and pressures in pneumatic nozzles open up a wide spectrum of cooling possibilities by their influence on droplet diameter, d, droplet velocity, v, and water impact flux, w. Nonetheless, due to the harsh environment resulting from the high temperatures and dense mists involved, there is very little information about the correlation between heat flux extracted, - q, and mist characteristics, and none about the dynamics of drop-wall interactions. For obtaining both kinds of information, this work combines a steady-state heat flux measuring method with a visualization technique based on a high-speed camera and a laser illumination system. For wall temperatures, T w, between ~723 K and ~1453 K (~450 °C and ~1180 °C), which correspond to film boiling regime, it was confirmed that - q increases with increase in v, w, and T w and with decrease in d. It should be noticed, however, that the increase in w generally decreases the spray cooling effectiveness because striking drops do not evaporate efficiently due to the interference by liquid remains from previous drops. Visualization of the events happening close to the surface also reveals that the contact time of the liquid with the surface is very brief and that rebounding, splashing, sliding, and levitation of drops lead to ineffective contact with the surface. At the center of the mist footprint, where drops impinge nearly normal to the surface those with enough momentum establish intimate contact with it before forming a vapor layer that pushes away the remaining liquid. Also, some drops are observed sliding upon the surface or levitating close to it; these are drops with low momentum which are influenced by the deflecting air stream. At footprint positions where oblique impingement occurs, frequently drops are spotted sliding or levitating and liquid films flowing in

  13. Solving the heat transfer in the cold rain of a cross flow cooling tower. N3S code - cooling tower release; Traitement thermique de la zone de pluie des aerorefrigerants a contre-courant. Code N3S - version aerorefrigerants

    Energy Technology Data Exchange (ETDEWEB)

    Grange, J.L.

    1996-09-01

    A simplified model for heat and mass transfer in the lower rainfall of a counter-flow cooling toward had to be implemented in the N3S code-cooling tower release It is built from an old code: ZOPLU. The air velocity field is calculated by N3S. The air and water temperature fields are solved by a Runge-Kutta method on a mesh in an adequate number of vertical plans. Heat exchange and drags correlations are given. And all the necessary parameters are specified. All the subroutines are described. They are taken from ZOPLU and modified in order to adapt their abilities to the N3S requirements. (author). 6 refs., 3 figs., 3 tabs., 3 appends.

  14. Heat transfer, diffusion, and evaporation

    Science.gov (United States)

    Nusselt, Wilhelm

    1954-01-01

    Although it has long been known that the differential equations of the heat-transfer and diffusion processes are identical, application to technical problems has only recently been made. In 1916 it was shown that the speed of oxidation of the carbon in iron ore depends upon the speed with which the oxygen of the combustion air diffuses through the core of gas surrounding the carbon surface. The identity previously referred to was then used to calculate the amount of oxygen diffusing to the carbon surface on the basis of the heat transfer between the gas stream and the carbon surface. Then in 1921, H. Thoma reversed that procedure; he used diffusion experiments to determine heat-transfer coefficients. Recently Lohrisch has extended this work by experiment. A technically very important application of the identity of heat transfer and diffusion is that of the cooling tower, since in this case both processes occur simultaneously.

  15. Basic heat transfer

    CERN Document Server

    Bacon, D H

    2013-01-01

    Basic Heat Transfer aims to help readers use a computer to solve heat transfer problems and to promote greater understanding by changing data values and observing the effects, which are necessary in design and optimization calculations.The book is concerned with applications including insulation and heating in buildings and pipes, temperature distributions in solids for steady state and transient conditions, the determination of surface heat transfer coefficients for convection in various situations, radiation heat transfer in grey body problems, the use of finned surfaces, and simple heat exc

  16. Economics of heat pump systems for simultaneous heating and cooling

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, S.; Devotta, S.; Patwardhan, V.S.

    1987-01-01

    Heat pumps can be incorporated advantageously into processes which require simultaneously both cooling and heating. The economics of heat pumps in India for simultaneous heat and cooling is assessed with respect to process, design and economic parameters. For the typical conditions of various parameters in India, a heat pump system for simultaneous heating and cooling is very attractive.

  17. Renewables for Heating and Cooling

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    This timely report examines the technologies, current markets and relative costs for heat and cold production using biomass, geothermal and solar-assisted systems. It evaluates a range of national case studies and relevant policies. Should the successful and more cost-effective policies be implemented by other countries, then the relatively untapped economic potential of renewable energy heating and cooling systems could be better realised, resulting in potential doubling of the present market within the next few years.

  18. Experimental Study of the Effect of Graphite Dispersion on the Heat Transfer Phenomena in a Reactor Cavity Cooling System

    Energy Technology Data Exchange (ETDEWEB)

    Vaghetto, Rodolfo; Capone, Luigi; Hassan, Yassin A

    2011-05-31

    An experimental activity was performed to observe and study the effects of graphite dispersion and deposition on thermal-hydraulic phenomena in a reactor cavity cooling system (RCCS). The small-scale RCCS experimental facility (16.5 x 16.5 x 30.4 cm) used for this activity represents half of the reactor cavity with an electrically heated vessel. Water flowing through five vertical pipes removes the heat produced in the vessel and releases it into the environment by mixing with cold water in a large tank. The particle image velocimetry technique was used to study the velocity field of the air inside the cavity. A set of 52 thermocouples was installed in the facility to monitor the temperature profiles of the vessel, pipe walls, and air. Ten grams of a fine graphite powder (average particle size 2 m) was injected into the cavity through a spraying nozzle placed at the bottom of the vessel. The temperatures and air velocity field were recorded and compared with the measurements obtained before the graphite dispersion, showing a decrease of the temperature surfaces that was related to an increase in their emissivity. The results contribute to the understanding of RCCS capability in an accident scenario.

  19. Thermal radiation heat transfer

    CERN Document Server

    Howell, John R; Siegel, Robert

    2016-01-01

    Further expanding on the changes made to the fifth edition, Thermal Radiation Heat Transfer, 6th Edition continues to highlight the relevance of thermal radiative transfer and focus on concepts that develop the radiative transfer equation (RTE). The book explains the fundamentals of radiative transfer, introduces the energy and radiative transfer equations, covers a variety of approaches used to gauge radiative heat exchange between different surfaces and structures, and provides solution techniques for solving the RTE.

  20. Superior heat transfer fluids for solar heating and cooling applications. Final report, 21 August 1978-31 December 1979. Report MRC-DA-953

    Energy Technology Data Exchange (ETDEWEB)

    Parts, L; Miller, D R; Leffingwell, J W; Thompson, Q E

    1980-09-01

    The major objective of this program was the identification of superior, currently available organic heat transfer fluids for solar collector applications. Organic fluids used in the form of aqueous solutions were also to be identified. The required design and handling properties of the fluids were determined through a survey in which 115 designers and manufacturers of solar collectors and collection systems participated. A state-of-the-art survey of commercially available organic heat transfer fluids provided information on fifty fluids. These were grouped into nine classes. This report contains information on limiting, design, and handling properties of these fluids. The limiting properties affix the use temperature ranges of the fluids. The design properties include the following thermophysical data: densities, vapor pressures, viscosities, specific heats, thermal conductivities, heats of vaporization, and coefficients of thermal expansion. The handling properties include: compatibility and incompatibility, with construction materials, chemical sensitivity, ignitability, physiological effects, and biodegradability characteristics. Mutagenicity tests with Salmonella typhimurium bacteria, and ignitability tests were conducted with a number of fluids in this program. The properties of the fluids were analyzed with reference to the required design and handling properties established in the survey of collector manufacturers. Guidelines are provided for the selection of superior fluids to meet specific collector operational and compatibility requirements. These guidelines include the use of heat transfer efficiency factors, that were calculated or the temperature ranges for which thermophysical data were available.

  1. Local heat/mass transfer and pressure drop in a two-pass rib-roughened channel for turbine airfoil cooling

    Science.gov (United States)

    Han, J. C.; Chandra, P. R.

    1987-01-01

    The heat transfer characteristics of turbulent air flow in a multipass channel were studied via the naphthalene sublimation technique. The naphthalene-coated test section, consisting of two straight, square channels joined by a 180 deg turn, resembled the internal cooling passages of gas turbine airfoils. The top and bottom surfaces of the test channel were roughened by rib turbulators. The rib height-to-hydraulic diameter ratio (e/D) were 0.063 and 0.094, and the rib pitch-to-height ratio (P/e) were 10 and 20. The local heat/mass transfer coefficients on the roughened top wall and on the smooth divider and side walls of the test channel were determined for three Reynolds numbers of 15, 30, and 60, thousand, and for three angles of attack (alpha) of 90, 60, and 45 deg. Results showed that the local Sherwood numbers on the ribbed walls were 1.5 to 6.5 times those for a fully developed flow in a smooth square duct. The average ribbed-wall Sherwood numbers were 2.5 to 3.5 times higher than the fully developed values, depending on the rib angle of attack and the Reynolds number. The results also indicated that, before the turn, the heat/mass transfer coefficients in the cases of alpha = 60 and 45 deg were higher than those in the case of alpha=90 deg. However, after the turn, the heat/mass transfer coefficients in the oblique-rib cases were lower than those in the transverse rib case. Correlations for the average Sherwood number ratios for individual channel surfaces and for the overall Sherwood number ratios are reported. Correlations for the fully developed friction factors and for the loss coefficients are also provided.

  2. Peltier Junction heats and cools car seat

    Energy Technology Data Exchange (ETDEWEB)

    Gottschalk, M.A.

    1994-10-10

    Electrically heated seats may soon become heated and cooled seats. The design called the CCS module exploits the heat-pump capability of a class of semiconductor thermoelectric devices (TEDs) known as Peltier Junction. Every CCS module contain two TEDs. Heating and cooling occurs through convection and conduction. The heart of the system is the thermoelectric heat pump. This is originally conceived as the sole heating/cooling options for a prototype electric vehicle.

  3. Pressure drop, heat transfer, critical heat flux, and flow stability of two-phase flow boiling of water and ethylene glycol/water mixtures - final report for project "Efficent cooling in engines with nucleate boiling."

    Energy Technology Data Exchange (ETDEWEB)

    Yu, W.; France, D. M.; Routbort, J. L. (Energy Systems)

    2011-01-19

    Because of its order-of-magnitude higher heat transfer rates, there is interest in using controllable two-phase nucleate boiling instead of conventional single-phase forced convection in vehicular cooling systems to remove ever increasing heat loads and to eliminate potential hot spots in engines. However, the fundamental understanding of flow boiling mechanisms of a 50/50 ethylene glycol/water mixture under engineering application conditions is still limited. In addition, it is impractical to precisely maintain the volume concentration ratio of the ethylene glycol/water mixture coolant at 50/50. Therefore, any investigation into engine coolant characteristics should include a range of volume concentration ratios around the nominal 50/50 mark. In this study, the forced convective boiling heat transfer of distilled water and ethylene glycol/water mixtures with volume concentration ratios of 40/60, 50/50, and 60/40 in a 2.98-mm-inner-diameter circular tube has been investigated in both the horizontal flow and the vertical flow. The two-phase pressure drop, the forced convective boiling heat transfer coefficient, and the critical heat flux of the test fluids were determined experimentally over a range of the mass flux, the vapor mass quality, and the inlet subcooling through a new boiling data reduction procedure that allowed the analytical calculation of the fluid boiling temperatures along the experimental test section by applying the ideal mixture assumption and the equilibrium assumption along with Raoult's law. Based on the experimental data, predictive methods for the two-phase pressure drop, the forced convective boiling heat transfer coefficient, and the critical heat flux under engine application conditions were developed. The results summarized in this final project report provide the necessary information for designing and implementing nucleate-boiling vehicular cooling systems.

  4. Heat transfer equipment design

    Science.gov (United States)

    Shah, R. K.; Subbarao, Eleswarapu Chinna; Mashelkar, R. A.

    A comprehensive presentation is made of state-of-the-art configurations and design methodologies for heat transfer devices applicable to industrial processes, automotive systems, air conditioning/refrigeration, cryogenics, and petrochemicals refining. Attention is given to topics in heat exchanger mechanical design, single-phase convection processes, thermal design, two-phase exchanger thermal design, heat-transfer augmentation, and rheological effects. Computerized analysis and design methodologies are presented for the range of heat transfer systems, as well as advanced methods for optimization and performance projection.

  5. Effects of high free-flow turbulence, intensive cooling, and wake on the external heat transfer of a gas turbine blade with external heat transfer. Zum Einfluss hoher Freistromturbulenz, intensiver Kuehlung und einer Nachlaufstroemung auf den aeusseren Waermeuebergang einer konvektiv gekuehlten Gasturbinenschaufel

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, A.V.

    1986-04-18

    The effects of free flow turbulence on the heat transfer characteristics of a gas turbine blade with convective cooling are investigated in hot-gas conditions, making a rigid distribution between isotropic turbulence and the free laminar turbulence of a wake flow. The influence of different Reynolds numbers of the grid flow and of different degrees of surface cooling is determined by means of heat transfer experiments with isotropic turbulence generated by quadratic grids. Experimental heat transfer data are compared with the results of a difference boundary layer calculation. The free flow turbulence is determined by laser doppler anemometry while the temperature field is calculated by a finite element method with experimentally determined boundary conditions. Another factor investigated was the effect of a wake on the heat transfer along the blade surface. A turbulent wake was simulated and discussed. (HAG).

  6. Axial flow heat exchanger devices and methods for heat transfer using axial flow devices

    Energy Technology Data Exchange (ETDEWEB)

    Koplow, Jeffrey P.

    2016-02-16

    Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.

  7. Heat transfer II essentials

    CERN Document Server

    REA, The Editors of

    1988-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Heat Transfer II reviews correlations for forced convection, free convection, heat exchangers, radiation heat transfer, and boiling and condensation.

  8. Advances in heat transfer

    CERN Document Server

    Hartnett, James P; Cho, Young I; Greene, George A

    2001-01-01

    Heat transfer is the exchange of heat energy between a system and its surrounding environment, which results from a temperature difference and takes place by means of a process of thermal conduction, mechanical convection, or electromagnetic radiation. Advances in Heat Transfer is designed to fill the information gap between regularly scheduled journals and university-level textbooks by providing in-depth review articles over a broader scope than is allowable in either journals or texts.

  9. Convection heat transfer

    CERN Document Server

    Bejan, Adrian

    2013-01-01

    Written by an internationally recognized authority on heat transfer and thermodynamics, this second edition of Convection Heat Transfer contains new and updated problems and examples reflecting real-world research and applications, including heat exchanger design. Teaching not only structure but also technique, the book begins with the simplest problem solving method (scale analysis), and moves on to progressively more advanced and exact methods (integral method, self similarity, asymptotic behavior). A solutions manual is available for all problems and exercises.

  10. Heat transfer. Basics and practice

    Energy Technology Data Exchange (ETDEWEB)

    Wetzel, Thomas [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany); Boeckh, Peter von

    2012-07-01

    The book provides an easy way to understand the fundamentals of heat transfer. The reader will acquire the ability to design and analyze heat exchangers. Without extensive derivation of the fundamentals, the latest correlations for heat transfer coefficients and their application are discussed. The following topics are presented - Steady state and transient heat conduction - Free and forced convection - Finned surfaces - Condensation and boiling - Radiation - Heat exchanger design - Problem-solving After introducing the basic terminology, the reader is made familiar with the different mechanisms of heat transfer. Their practical application is demonstrated in examples, which are available in the Internet as MathCad files for further use. Tables of material properties and formulas for their use in programs are included in the appendix. This book will serve as a valuable resource for both students and engineers in the industry. The author's experience indicates that students, after 40 lectures and exercises of 45 minutes based on this textbook, have proved capable of designing independently complex heat exchangers such as for cooling of rocket propulsion chambers, condensers and evaporators for heat pumps. (orig.)

  11. A study of boiling heat transfer as applied to the cooling of ball bearings in the high pressure oxygen turbopump of the space shuttle main engine

    Science.gov (United States)

    Schreiber, Will

    1986-01-01

    Two sets of ball bearings support the main shaft within the High Pressure Oxygen Turbopump (HPOTP) in the Space Shuttle Main Engine (SSME). In operation, these bearings are cooled and lubricated with high pressure liquid oxygen (LOX) flowing axially through the bearing assembly. Currently, modifications in the assembly design are being contemplated in order to enhance the lifetime of the bearings and to allow the HPOTP to operate under larger loads. An understanding of the fluid dynamics and heat transfer characteristics of the flowing LOX is necessary for the implementation of these design changes. The proposed computational model of the LOX fluid dynamics, in addition to dealing with a turbulent flow in a complex geometry, must address the complication associated with boiling and two-phase flow. The feasibility of and possible methods for modeling boiling heat transfer are considered. The theory of boiling as pertains to this particular problem is reviewed. Recommendations are given for experiments which would be necessary to establish validity for correlations needed to model boiling.

  12. Thermal-hydraulic analysis of heat transfer in subchannels of the European high performance supercritical Water-Cooled Reactor for different CFD turbulence models

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Landy Y.; Rojas, Leorlen Y.; Gamez, Abel; Rosales, Jesus; Gonzalez, Daniel; Garcia, Carlos, E-mail: lcastro@instec.cu, E-mail: leored1984@gmail.com, E-mail: agamezgmf@gmail.com, E-mail: jrosales@instec.cu, E-mail: danielgonro@gmail.com, E-mail: cgh@instec.cu [Instituto Superior de Tecnologias y Ciencias Aplicadas (InSTEC), La Habana (Cuba); Oliveira, Carlos Brayner de, E-mail: cabol@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Dominguez, Dany S., E-mail: dsdominguez@gmail.com [Universidade Estadual de Santa Cruz (UESC), Ilheus, BA (Brazil). Pos-Graduacao em Modelagem Computacional

    2015-07-01

    Chosen as one of six Generation‒IV nuclear-reactor concepts, Supercritical Water-cooled Reactors (SCWRs) are expected to have high thermal efficiencies within the range of 45 - 50% owing to the reactor's high pressures and outlet temperatures. In this reactor, the primary water enters the core under supercritical-pressure condition (25 MPa) at a temperature of 280 deg C and leaves it at a temperature of up to 510 deg C. Due to the significant changes in the physical properties of water at supercritical-pressure, the system is susceptible to local temperature, density and power oscillations. The behavior of supercritical water into the core of the SCWR, need to be sufficiently studied. Most of the methods available to predict the effects of the heat transfer phenomena within the pseudocritical region are based on empirical one-directional correlations, which do not capture the multidimensional effects and do not provide accurate results in regions such as the deteriorated heat transfer regime. In this paper, computational fluid dynamics (CFD) analysis was carried out to study the thermal-hydraulic behavior of supercritical water flows in sub-channels of a typical European High Performance Light Water Reactor (HPLWR) fuel assembly using commercial CFD code CFX-14. It was determined the steady-state equilibrium parameters and calculated the temperature and density distributions. A comparative study for different turbulence models were carried out and the obtained results are discussed. (author)

  13. Heating and Cooling Protostellar Disks

    CERN Document Server

    Hirose, S

    2011-01-01

    We examine heating and cooling in protostellar disks using 3-D radiation-MHD calculations of a patch of the Solar nebula at 1 AU, employing the shearing-box and flux-limited radiation diffusion approximations. The disk atmosphere is ionized by stellar X-rays, well-coupled to magnetic fields, and sustains a turbulent accretion flow driven by magneto-rotational instability, while the interior is resistive and magnetically dead. The turbulent layers heat by absorbing the light from the central star and by dissipating the magnetic fields. They are optically-thin to their own radiation and cool inefficiently. The optically-thick interior in contrast is heated only weakly, by re-emission from the atmosphere. The interior is colder than a classical viscous model, and isothermal. The magnetic fields support an extended atmosphere that absorbs the starlight 1.5 times higher than the hydrostatic viscous model. The disk thickness thus measures not the internal temperature, but the magnetic field strength. Fluctuations i...

  14. Radiative heat transfer

    CERN Document Server

    Modest, Michael F

    2013-01-01

    The third edition of Radiative Heat Transfer describes the basic physics of radiation heat transfer. The book provides models, methodologies, and calculations essential in solving research problems in a variety of industries, including solar and nuclear energy, nanotechnology, biomedical, and environmental. Every chapter of Radiative Heat Transfer offers uncluttered nomenclature, numerous worked examples, and a large number of problems-many based on real world situations-making it ideal for classroom use as well as for self-study. The book's 24 chapters cover the four major areas in the field: surface properties; surface transport; properties of participating media; and transfer through participating media. Within each chapter, all analytical methods are developed in substantial detail, and a number of examples show how the developed relations may be applied to practical problems. It is an extensive solution manual for adopting instructors. Features: most complete text in the field of radiative heat transfer;...

  15. Numerical simulation of heat transfer physics of film cooling under rotating conditions%旋转状态气膜换热机理的数值研究

    Institute of Scientific and Technical Information of China (English)

    刘宁; 孙纪宁

    2011-01-01

    Large eddy simulation was used to investigate the effect of rotation on film cooling over flat plate with single hole. The Reynolds number at the jet exit was 2 600, and the blowing ratio was 0. 5. The flow and heat transfer without rotation and with rotating number of 0. 02 were calculated, and the heat transfer mechanics under rotating condition was analyzed through the evolvement of turbulence structure. It was found that hairpin structure determined the heat transfer of film cooling, and the shape and trajectory of hairpin structure was mainly affected by Coriolis force under rotating condition. The film was driven towards high radius side by spanwise Coriolis force, resulting in less mixing between main flow and jet and maintaining low temperature of the film. The Coriolis force normal to the wall reinforced the film attachment and reduced the strength of counter rotating vortex pair, leading to less entrainment of mainflow and better coverage of film.%大涡模拟研究了旋转对单孔平板气膜冷却的影响,气膜出流的雷诺数为2600,吹风比为0.5,计算了静止和旋转数为0.02两种状态的流动和换热,从湍流结构演化的角度讨论了旋转状态气膜换热的机理.结果表明:①发卡涡是决定气膜换热的主要湍流结构,旋转状态发卡涡的形状和运动规律主要受哥氏力的影响;②气膜在哥氏力作用下向高半径方向偏移,弱化了射流前缘与主流的剪切和掺混,使气膜保持较低温度;③气膜的侧向速度诱发垂直向下的哥氏力,压制射流贴附壁面,并降低对转涡对的强度,减少了对主流的卷吸,增强了气膜的保护效果.

  16. Boundary conditions for heat transfer and evaporative cooling in the trachea and air sac system of the domestic fowl: a two-dimensional CFD analysis.

    Science.gov (United States)

    Sverdlova, Nina S; Lambertz, Markus; Witzel, Ulrich; Perry, Steven F

    2012-01-01

    Various parts of the respiratory system play an important role in temperature control in birds. We create a simplified computational fluid dynamics (CFD) model of heat exchange in the trachea and air sacs of the domestic fowl (Gallus domesticus) in order to investigate the boundary conditions for the convective and evaporative cooling in these parts of the respiratory system. The model is based upon published values for respiratory times, pressures and volumes and upon anatomical data for this species, and the calculated heat exchange is compared with experimentally determined values for the domestic fowl and a closely related, wild species. In addition, we studied the trachea histologically to estimate the thickness of the heat transfer barrier and determine the structure and function of moisture-producing glands. In the transient CFD simulation, the airflow in the trachea of a 2-dimensional model is evoked by changing the volume of the simplified air sac. The heat exchange between the respiratory system and the environment is simulated for different ambient temperatures and humidities, and using two different models of evaporation: constant water vapour concentration model and the droplet injection model. According to the histological results, small mucous glands are numerous but discrete serous glands are lacking on the tracheal surface. The amount of water and heat loss in the simulation is comparable with measured respiratory values previously reported. Tracheal temperature control in the avian respiratory system may be used as a model for extinct or rare animals and could have high relevance for explaining how gigantic, long-necked dinosaurs such as sauropoda might have maintained a high metabolic rate.

  17. Boundary conditions for heat transfer and evaporative cooling in the trachea and air sac system of the domestic fowl: a two-dimensional CFD analysis.

    Directory of Open Access Journals (Sweden)

    Nina S Sverdlova

    Full Text Available Various parts of the respiratory system play an important role in temperature control in birds. We create a simplified computational fluid dynamics (CFD model of heat exchange in the trachea and air sacs of the domestic fowl (Gallus domesticus in order to investigate the boundary conditions for the convective and evaporative cooling in these parts of the respiratory system. The model is based upon published values for respiratory times, pressures and volumes and upon anatomical data for this species, and the calculated heat exchange is compared with experimentally determined values for the domestic fowl and a closely related, wild species. In addition, we studied the trachea histologically to estimate the thickness of the heat transfer barrier and determine the structure and function of moisture-producing glands. In the transient CFD simulation, the airflow in the trachea of a 2-dimensional model is evoked by changing the volume of the simplified air sac. The heat exchange between the respiratory system and the environment is simulated for different ambient temperatures and humidities, and using two different models of evaporation: constant water vapour concentration model and the droplet injection model. According to the histological results, small mucous glands are numerous but discrete serous glands are lacking on the tracheal surface. The amount of water and heat loss in the simulation is comparable with measured respiratory values previously reported. Tracheal temperature control in the avian respiratory system may be used as a model for extinct or rare animals and could have high relevance for explaining how gigantic, long-necked dinosaurs such as sauropoda might have maintained a high metabolic rate.

  18. Condensation heat transfer

    Science.gov (United States)

    Rose, J. W.

    The paper gives a brief description of some of the better understood aspects of condensation heat transfer and includes discussion of the liquid-vapour interface, natural and forced convection laminar film condensation and dropwise condensation.

  19. Analytical heat transfer

    CERN Document Server

    Han, Je-Chin

    2012-01-01

    … it will complete my library … [and] complement the existing literature on heat transfer. It will be of value for both graduate students and faculty members.-Bengt Sunden, Lund University, Sweden

  20. 46 CFR 153.430 - Heat transfer systems; general.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Heat transfer systems; general. 153.430 Section 153.430... Temperature Control Systems § 153.430 Heat transfer systems; general. Each cargo cooling system required by... separated from all other cooling and heating systems; and (c) Allow manual regulation of the system's...

  1. Heat Transfer in Gas Turbines

    Science.gov (United States)

    Garg, Vijay K.

    2001-01-01

    The turbine gas path is a very complex flow field. This is due to a variety of flow and heat transfer phenomena encountered in turbine passages. This manuscript provides an overview of the current work in this field at the NASA Glenn Research Center. Also, based on the author's preference, more emphasis is on the computational work. There is much more experimental work in progress at GRC than that reported here. While much has been achieved, more needs to be done in terms of validating the predictions against experimental data. More experimental data, especially on film cooled and rough turbine blades, are required for code validation. Also, the combined film cooling and internal cooling flow computation for a real blade is yet to be performed. While most computational work to date has assumed steady state conditions, the flow is clearly unsteady due to the presence of wakes. All this points to a long road ahead. However, we are well on course.

  2. Coupled calculation of external heat transfer and material temperatures of convection-cooled turbine blades. Final report; Gekoppelte Berechnung des aeusseren Waermeuebergangs und der Materialtemperaturen konvektionsgekuehlter Turbinenschaufeln. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Heselhaus, A.

    1997-05-01

    In this work a hybrid program system consisting of a 3D finite-volume Navier-Stokes flow solver and a 3D finite-element heat conduction solver has been developed. It enables the coupled calculation of structure temperatures in diabatic solid/fluid configurations. The grids of both the finite element and the finite volume computational domain may be completely independent. The coupled program fully resolves the thermal interaction between heat transfer and the resulting material temperatures. The developed coupling algorithm is numerically stable, conservative and works without the need to define ambient temperatures in the flowfield. This allows for the simulation of any solid/fluid configuration. When simulating combined blade/endwall cooling or filmcooling, only a coupled procedure is capable to completely account for the interaction between all relevant thermal parameters. It is found that the coupled calculation of convective cooling in a realistic guide vane leads locally to 45 K higher and 107 K lower blade temperatures than the uncoupled calculation. This shows that accounting for the thermal interaction between the flow and the structure offers both potential to save cooling air and a lower margin of safety when designing cooling systems close to the thermal limits of the blade material. (orig.) [Deutsch] Im Rahmen der vorliegenden Arbeit wurde ein Verfahren zur Berechnung der Temperaturverteilung in diabat umstroemten Koerpern entwickelt, bei dem ein 3D-Finite Volumen Navier-Stokes Stroemungsloeser und ein 3D-Finite Elemente Waermeleitungsloeser zu einem hybriden Programmsystem gekoppelt werden. Dabei besteht die Moeglichkeit, voellig unabhaengige Rechennetze fuer Stroemung und Struktur zu verwenden. Mit dem gekoppelten Verfahren kann die Wechselwirkung zwischen resultierenden Materialtemperaturen und dem davon rueck-beeinflussten Waermeuebergang beruecksichtigt werden. Weiterhin ist der hier entwickelte, stabile und konservative Kopplungsalgorithmus nicht

  3. A thermosyphon heat pipe cooler for high power LEDs cooling

    Science.gov (United States)

    Li, Ji; Tian, Wenkai; Lv, Lucang

    2016-08-01

    Light emitting diode (LED) cooling is facing the challenge of high heat flux more seriously with the increase of input power and diode density. The proposed unique thermosyphon heat pipe heat sink is particularly suitable for cooling of high power density LED chips and other electronics, which has a heat dissipation potential of up to 280 W within an area of 20 mm × 22 mm (>60 W/cm2) under natural air convection. Meanwhile, a thorough visualization investigation was carried out to explore the two phase flow characteristics in the proposed thermosyphon heat pipe. Implementing this novel thermosyphon heat pipe heat sink in the cooling of a commercial 100 W LED integrated chip, a very low apparent thermal resistance of 0.34 K/W was obtained under natural air convection with the aid of the enhanced boiling heat transfer at the evaporation side and the enhanced natural air convection at the condensation side.

  4. Heat and mass transfer in particulate suspensions

    CERN Document Server

    Michaelides, Efstathios E (Stathis)

    2013-01-01

    Heat and Mass Transfer in Particulate Suspensions is a critical review of the subject of heat and mass transfer related to particulate Suspensions, which include both fluid-particles and fluid-droplet Suspensions. Fundamentals, recent advances and industrial applications are examined. The subject of particulate heat and mass transfer is currently driven by two significant applications: energy transformations –primarily combustion – and heat transfer equipment. The first includes particle and droplet combustion processes in engineering Suspensions as diverse as the Fluidized Bed Reactors (FBR’s) and Internal Combustion Engines (ICE’s). On the heat transfer side, cooling with nanofluids, which include nanoparticles, has attracted a great deal of attention in the last decade both from the fundamental and the applied side and has produced several scientific publications. A monograph that combines the fundamentals of heat transfer with particulates as well as the modern applications of the subject would be...

  5. Elementary heat transfer analysis

    CERN Document Server

    Whitaker, Stephen; Hartnett, James P

    1976-01-01

    Elementary Heat Transfer Analysis provides information pertinent to the fundamental aspects of the nature of transient heat conduction. This book presents a thorough understanding of the thermal energy equation and its application to boundary layer flows and confined and unconfined turbulent flows. Organized into nine chapters, this book begins with an overview of the use of heat transfer coefficients in formulating the flux condition at phase interface. This text then explains the specification as well as application of flux boundary conditions. Other chapters consider a derivation of the tra

  6. A heat transfer textbook

    CERN Document Server

    Lienhard, John H

    2011-01-01

    This introduction to heat transfer offers advanced undergraduate and graduate engineering students a solid foundation in the subjects of conduction, convection, radiation, and phase-change, in addition to the related topic of mass transfer. A staple of engineering courses around the world for more than three decades, it has been revised and updated regularly by the authors, a pair of recognized experts in the field. The text addresses the implications, limitations, and meanings of many aspects of heat transfer, connecting the subject to its real-world applications and developing students' ins

  7. Heat and mass transfer

    CERN Document Server

    Karwa, Rajendra

    2017-01-01

    This textbook presents the classical treatment of the problems of heat transfer in an exhaustive manner with due emphasis on understanding of the physics of the problems. This emphasis is especially visible in the chapters on convective heat transfer. Emphasis is laid on the solution of steady and unsteady two-dimensional heat conduction problems. Another special feature of the book is a chapter on introduction to design of heat exchangers and their illustrative design problems. A simple and understandable treatment of gaseous radiation has been presented. A special chapter on flat plate solar air heater has been incorporated that covers thermo-hydraulic modeling and simulation. The chapter on mass transfer has been written looking specifically at the needs of the students of mechanical engineering. The book includes a large number and variety of solved problems with supporting line diagrams. The author has avoided duplicating similar problems, while incorporating more application-based examples. All the end-...

  8. Fluid-cooled heat sink with improved fin areas and efficiencies for use in cooling various devices

    Science.gov (United States)

    Bharathan, Desikan; Bennion, Kevin; Kelly, Kenneth; Narumanchi, Sreekant

    2015-04-21

    The disclosure provides a fluid-cooled heat sink having a heat transfer base and a plurality of heat transfer fins in thermal communication with the heat transfer base, where the heat transfer base and the heat transfer fins form a central fluid channel through which a forced or free cooling fluid may flow. The heat transfer pins are arranged around the central fluid channel with a flow space provided between adjacent pins, allowing for some portion of the central fluid channel flow to divert through the flow space. The arrangement reduces the pressure drop of the flow through the fins, optimizes average heat transfer coefficients, reduces contact and fin-pin resistances, and reduces the physical footprint of the heat sink in an operating environment.

  9. Hypersonic aerospace vehicle leading edge cooling using heat pipe, transpiration and film cooling techniques

    Science.gov (United States)

    Modlin, James Michael

    An investigation was conducted to study the feasibility of cooling hypersonic vehicle leading edge structures exposed to severe aerodynamic surface heat fluxes using a combination of liquid metal heat pipes and surface mass transfer cooling techniques. A generalized, transient, finite difference based hypersonic leading edge cooling model was developed that incorporated these effects and was demonstrated on an assumed aerospace plane-type wing leading edge section and a SCRAMJET engine inlet leading edge section. The hypersonic leading edge cooling model was developed using an existing, experimentally verified heat pipe model. Two applications of the hypersonic leading edge cooling model were examined. An assumed aerospace plane-type wing leading edge section exposed to a severe laminar, hypersonic aerodynamic surface heat flux was studied. A second application of the hypersonic leading edge cooling model was conducted on an assumed one-quarter inch nose diameter SCRAMJET engine inlet leading edge section exposed to both a transient laminar, hypersonic aerodynamic surface heat flux and a type 4 shock interference surface heat flux. The investigation led to the conclusion that cooling leading edge structures exposed to severe hypersonic flight environments using a combination of liquid metal heat pipe, surface transpiration, and film cooling methods appeared feasible.

  10. Numerical Study on Flow and Heat Transfer Characteristics of Finned Tube Bundles for Air-cooled Heat Exchangers of Indirect Dry Cooling Systems in Power Plants%电站间冷系统空冷散热器翅片管束流动传热性能的数值研究

    Institute of Scientific and Technical Information of China (English)

    杨立军; 贾思宁; 卜永东; 杜小泽; 杨勇平

    2012-01-01

    空冷散热器为电站间接空冷系统的主要设备,研究空冷散热器翅片管束的流动传热特性,对于电站间冷系统的优化设计与高效运行具有重要意义.对间接空冷系统空冷散热器常用翅片管束流动传热性能进行了数值模拟研究,通过计算获得了空冷散热器冷却空气流动阻力和平均对流换热系数随迎面风速的变化规律,拟合得到了摩擦因子与努赛尔特数随雷诺数的变化关系.利用对流换热的综合性能评价标准(performance evaluation criteria,PEC),即Nu/f1/3,对6种翅片管束的流动传热性能进行了比较.结果表明,随迎面风速增加,空气对流换热增强,压降增加,翅片管的对流换热系数随之升高,摩擦因子降低,但是换热系数的增加幅度小于压降的增加幅度.Forgo型翅片管束综合流动传热性能优于椭圆型管束.本文研究结果为电站间冷系统空冷散热器的选型和优化设计提供了一定的理论依据.%Air-cooled heat exchanger is one of the main components of the indirect dry cooling system in a power plant. It is of benefit to the optimal design and operation of indirect dry cooling system to clarify the flow and heat transfer characteristics of air-cooled finned tube heat exchangers. The thermo-flow performances of the commonly used finned tube bundles in air-cooled heat exchangers were investigated by a numerical simulation. The variations of the flow resistance and average convection heat transfer coefficient of cooling air through the finned tube heat exchanger with the windward velocity were presented. The correlating equations of the friction factor versus Reynolds number, and the Nusselt number versus Reynolds number were fitted. On the basis of the performance evaluation criteria for convection heat transfer, the expression of Nu/f1/3 was applied to the thermo-flow performances prediction for six finned tube bundles. The results show that as the windward velocity increases

  11. Development of the Glenn-Heat-Transfer (Glenn-HT) Computer Code to Enable Time-Filtered Navier Stokes (TFNS) Simulations and Application to Film Cooling on a Flat Plate Through Long Cooling Tubes

    Science.gov (United States)

    Ameri, Ali A.; Shyam, Vikram; Rigby, David; Poinsatte, Phillip; Thurman, Douglas; Steinthorsson, Erlendur

    2014-01-01

    Computational fluid dynamics (CFD) analysis using Reynolds-averaged Navier-Stokes (RANS) formulation for turbomachinery-related flows has enabled improved engine component designs. RANS methodology has limitations that are related to its inability to accurately describe the spectrum of flow phenomena encountered in engines. Examples of flows that are difficult to compute accurately with RANS include phenomena such as laminar/turbulent transition, turbulent mixing due to mixing of streams, and separated flows. Large eddy simulation (LES) can improve accuracy but at a considerably higher cost. In recent years, hybrid schemes that take advantage of both unsteady RANS and LES have been proposed. This study investigated an alternative scheme, the time-filtered Navier-Stokes (TFNS) method applied to compressible flows. The method developed by Shih and Liu was implemented in the Glenn-Heat-Transfer (Glenn-HT) code and applied to film-cooling flows. In this report the method and its implementation is briefly described. The film effectiveness results obtained for film cooling from a row of 30deg holes with a pitch of 3.0 diameters emitting air at a nominal density ratio of unity and two blowing ratios of 0.5 and 1.0 are shown. Flow features under those conditions are also described.

  12. Development of the Glenn Heat-Transfer (Glenn-HT) Computer Code to Enable Time-Filtered Navier-Stokes (TFNS) Simulations and Application to Film Cooling on a Flat Plate Through Long Cooling Tubes

    Science.gov (United States)

    Ameri, Ali; Shyam, Vikram; Rigby, David; Poinsatte, Phillip; Thurman, Douglas; Steinthorsson, Erlendur

    2014-01-01

    Computational fluid dynamics (CFD) analysis using Reynolds-averaged Navier-Stokes (RANS) formulation for turbomachinery-related flows has enabled improved engine component designs. RANS methodology has limitations that are related to its inability to accurately describe the spectrum of flow phenomena encountered in engines. Examples of flows that are difficult to compute accurately with RANS include phenomena such as laminar/turbulent transition, turbulent mixing due to mixing of streams, and separated flows. Large eddy simulation (LES) can improve accuracy but at a considerably higher cost. In recent years, hybrid schemes that take advantage of both unsteady RANS and LES have been proposed. This study investigated an alternative scheme, the time-filtered Navier-Stokes (TFNS) method applied to compressible flows. The method developed by Shih and Liu was implemented in the Glenn-Heat-Transfer (Glenn-HT) code and applied to film-cooling flows. In this report the method and its implementation is briefly described. The film effectiveness results obtained for film cooling from a row of 30deg holes with a pitch of 3.0 diameters emitting air at a nominal density ratio of unity and two blowing ratios of 0.5 and 1.0 are shown. Flow features under those conditions are also described.

  13. Heat transfer fluids containing nanoparticles

    Science.gov (United States)

    Singh, Dileep; Routbort, Jules; Routbort, A.J.; Yu, Wenhua; Timofeeva, Elena; Smith, David S.; France, David M.

    2016-05-17

    A nanofluid of a base heat transfer fluid and a plurality of ceramic nanoparticles suspended throughout the base heat transfer fluid applicable to commercial and industrial heat transfer applications. The nanofluid is stable, non-reactive and exhibits enhanced heat transfer properties relative to the base heat transfer fluid, with only minimal increases in pumping power required relative to the base heat transfer fluid. In a particular embodiment, the plurality of ceramic nanoparticles comprise silicon carbide and the base heat transfer fluid comprises water and water and ethylene glycol mixtures.

  14. Heat and mass transfer

    CERN Document Server

    Baehr, Hans Dieter

    2011-01-01

    This comprehensive textbook provides a solid foundation of knowledge on the principles of heat and mass transfer and shows how to solve problems by applying modern methods. The basic theory is developed systematically, exploring in detail the solution methods to all important problems.   The thoroughly revised 3rd edition includes an introduction to the numerical solution of Finite Elements. A new section on heat and mass transfer in porous media has also been added.   The book will be useful not only to upper-level and graduate students, but also to practicing scientists and engineers, offering a firm understanding of the principles of heat and mass transfer, and showing how to solve problems by applying modern methods. Many completed examples and numerous exercises with solutions facilitate learning and understanding, and an appendix includes data on key properties of important substances.

  15. Thermal radiation heat transfer

    CERN Document Server

    Howell, John R; Mengüç, M Pinar

    2011-01-01

    Providing a comprehensive overview of the radiative behavior and properties of materials, the fifth edition of this classic textbook describes the physics of radiative heat transfer, development of relevant analysis methods, and associated mathematical and numerical techniques. Retaining the salient features and fundamental coverage that have made it popular, Thermal Radiation Heat Transfer, Fifth Edition has been carefully streamlined to omit superfluous material, yet enhanced to update information with extensive references. Includes four new chapters on Inverse Methods, Electromagnetic Theory, Scattering and Absorption by Particles, and Near-Field Radiative Transfer Keeping pace with significant developments, this book begins by addressing the radiative properties of blackbody and opaque materials, and how they are predicted using electromagnetic theory and obtained through measurements. It discusses radiative exchange in enclosures without any radiating medium between the surfaces-and where heat conduction...

  16. Heat Transfer Coefficient and Film Cooling Effectiveness on a Full-Film Cooling Vane%全气膜冷却叶片表面换热系数和冷却效率研究

    Institute of Scientific and Technical Information of China (English)

    张宗卫; 朱惠人; 刘聪; 孟庆昆

    2012-01-01

    The high-resolution heat transfer coefficient and the film effectiveness measurements on a full-film cooling nozzle guide vane with compound and axial angle holes were obtained using a transient liquid crystal technique. The tests were performed in a scaled-up, two-passage cascade at an inlet Reynolds number of 1.0×105. There are eight rows of compound angle cylinder film holes around the leading edge, 21 rows of axial angle cylinder holes on the pressure side, and 24 rows of axial angle cylinder holes on the suction side. The holes are fed from two internal plenum with a mass flow ratio of 4. 56% in the first plenum and 4. 67% in the second plenum. The results show that the film cover region shrinks on the suction side and expands on the pressure side due to the influence of passage vortex. The heat transfer coefficient and the film cooling effectiveness are higher in the near hole region. The heat transfer coefficient is higher and the film cooling effectiveness is lower near the leading edge. The film cooling effectiveness is about 0. 4 on the suction side and about 0. 35 on the pressure side, respectively.%为了研究全气膜冷却涡轮导叶叶片的换热特性,采用瞬态液晶技术获得了叶片全表面的高分辨率换热系数和冷却效率.实验在三叶片两通道放大模型中完成,叶栅进口雷诺数是1.0×105. 叶片前缘有8排复合角孔,压力面有21排轴向角孔,吸力面有24排轴向角孔.气膜孔排由2个供气腔供气,前腔二次流与主流的质量流量比为4.56%,后腔为4.67%.结果表明:受叶栅通道涡作用,气膜出流在吸力面呈聚敛状,在压力面则呈发散状.气膜出流受气膜孔角度影响,气膜孔下游的换热系数和冷却效率都较高.叶片前缘受到冲击,换热强,冷却效率低;叶片吸力面冷却效率维持在0.4左右,压力面维持在0.35左右.该全气膜冷却叶片气膜覆盖效果较好,冷却效率和换热系数分布均匀,是一种较好的冷却结构.

  17. Heat Transfer Phenomena of Supercritical Fluids

    Energy Technology Data Exchange (ETDEWEB)

    Krau, Carmen Isabella; Kuhn, Dietmar; Schulenberg, Thomas [Forschungszentrum Karlsruhe, Institute for Nuclear and Energy Technologies, 76021 Karlsruhe (Germany)

    2008-07-01

    In concepts for supercritical water cooled reactors, the reactor core is cooled and moderated by water at supercritical pressures. The significant temperature dependence of the fluid properties of water requires an exact knowledge of the heat transfer mechanism to avoid fuel pin damages. Near the pseudo-critical point a deterioration of heat transfer might happen. Processes, that take place in this case, are not fully understood and are due to be examined systematically. In this paper a general overview on the properties of supercritical water is given, experimental observations of different authors will be reviewed in order to identify heat transfer phenomena and onset of occurrence. The conceptional design of a test rig to investigate heat transfer in the boundary layer will be discussed. Both, water and carbon dioxide, may serve as operating fluids. The loop, including instrumentation and safety devices, is shown and suitable measuring methods are described. (authors)

  18. Solar heat utilization for adsorption cooling device

    Directory of Open Access Journals (Sweden)

    Malcho Milan

    2012-04-01

    Full Text Available This article deals with possibility of solar system connection with adsorption cooling system. Waste heat from solar collectors in summer is possible to utilize in adsorption cooling systems, which desorption temperatures have to be lower than temperature of heat transport medium operation temperature. For verification of work of this system was constructed on the Department of power engineering on University of Zilina solar adsorption cooling device.

  19. Experimental and numerical investigations of internal heat transfer in an innovative trailing edge blade cooling system: stationary and rotation effects, part 1—experimental results

    Science.gov (United States)

    Beniaiche, Ahmed; Ghenaiet, Adel; Facchini, Bruno

    2017-02-01

    The aero-thermal behavior of the flow field inside 30:1 scaled model reproducing an innovative smooth trailing edge of shaped wedge discharge duct with one row of enlarged pedestals have been investigated in order to determine the effect of rotation, inlet velocity and blowing conditions effects, for Re = 20,000 and 40,000 and Ro = 0-0.23. Two configurations are presented: with and without open tip configurations. Thermo-chromic liquid crystals technique is used to ensure a local measurement of the heat transfer coefficient on the blade suction side under stationary and rotation conditions. Results are reported in terms of detailed 2D HTC maps on the suction side surface as well as the averaged Nusselt number inside the pedestal ducts. Two correlations are proposed, for both closed and open tip configurations, based on the Re, Pr, Ro and a new non-dimensional parameter based on the position along the radial distance, to assess a reliable estimation of the averaged Nusselt number at the inter-pedestal region. A good agreement is found between prediction and experimental data with about ±10 to ±12 % of uncertainty, for the simple form correlation, and about ±16 % using a complex form. The obtained results help to predict the flow field visualization and the evaluation of the aero-thermal performance of the studied blade cooling system during the design step.

  20. Solar Energy: Heat Transfer.

    Science.gov (United States)

    Knapp, Henry H., III

    This module on heat transfer is one of six in a series intended for use as supplements to currently available materials on solar energy and energy conservation. Together with the recommended texts and references (sources are identified), these modules provide an effective introduction to energy conservation and solar energy technologies. The…

  1. Heat transfer coefficient of cryotop during freezing.

    Science.gov (United States)

    Li, W J; Zhou, X L; Wang, H S; Liu, B L; Dai, J J

    2013-01-01

    Cryotop is an efficient vitrification method for cryopreservation of oocytes. It has been widely used owing to its simple operation and high freezing rate. Recently, the heat transfer performance of cryotop was studied by numerical simulation in several studies. However, the range of heat transfer coefficient in the simulation is uncertain. In this study, the heat transfer coefficient for cryotop during freezing process was analyzed. The cooling rates of 40 percent ethylene glycol (EG) droplet in cryotop during freezing were measured by ultra-fast measurement system and calculated by numerical simulation at different value of heat transfer coefficient. Compared with the results obtained by two methods, the range of the heat transfer coefficient necessary for the numerical simulation of cryotop was determined, which is between 9000 W/(m(2)·K) and 10000 W/(m (2)·K).

  2. "Nanotechnology Enabled Advanced Industrial Heat Transfer Fluids"

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Ganesh Skandan; Dr. Amit Singhal; Mr. Kenneth Eberts; Mr. Damian Sobrevilla; Prof. Jerry Shan; Stephen Tse; Toby Rossmann

    2008-06-12

    ABSTRACT Nanotechnology Enabled Advanced industrial Heat Transfer Fluids” Improving the efficiency of Industrial Heat Exchangers offers a great opportunity to improve overall process efficiencies in diverse industries such as pharmaceutical, materials manufacturing and food processing. The higher efficiencies can come in part from improved heat transfer during both cooling and heating of the material being processed. Additionally, there is great interest in enhancing the performance and reducing the weight of heat exchangers used in automotives in order to increase fuel efficiency. The goal of the Phase I program was to develop nanoparticle containing heat transfer fluids (e.g., antifreeze, water, silicone and hydrocarbon-based oils) that are used in transportation and in the chemical industry for heating, cooling and recovering waste heat. Much work has been done to date at investigating the potential use of nanoparticle-enhanced thermal fluids to improve heat transfer in heat exchangers. In most cases the effect in a commercial heat transfer fluid has been marginal at best. In the Phase I work, we demonstrated that the thermal conductivity, and hence heat transfer, of a fluid containing nanoparticles can be dramatically increased when subjected to an external influence. The increase in thermal conductivity was significantly larger than what is predicted by commonly used thermal models for two-phase materials. Additionally, the surface of the nanoparticles was engineered so as to have a minimal influence on the viscosity of the fluid. As a result, a nanoparticle-laden fluid was successfully developed that can lead to enhanced heat transfer in both industrial and automotive heat exchangers

  3. Technology Roadmaps: Solar Heating and Cooling

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-07-01

    The solar heating and cooling (SHC) roadmap outlines a pathway for solar energy to supply almost one sixth (18 EJ) of the world’s total energy use for both heating and cooling by 2050. This would save some 800 megatonnes of carbon dioxide (CO2) emissions per year; more than the total CO2 emissions in Germany in 2009. While solar heating and cooling today makes a modest contribution to world energy demand, the roadmap envisages that if concerted action is taken by governments and industry, solar energy could annually produce more than 16% of total final energy use for low temperature heat and nearly 17% for cooling. Given that global energy demand for heat represents almost half of the world’s final energy use – more than the combined global demand for electricity and transport – solar heat can make a significant contribution in both tackling climate change and strengthening energy security.

  4. Technology Roadmaps: Solar Heating and Cooling

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-09-06

    The solar heating and cooling (SHC) roadmap outlines a pathway for solar energy to supply almost one sixth (18 EJ) of the world's total energy use for both heating and cooling by 2050. This would save some 800 megatonnes of carbon dioxide (CO2) emissions per year; more than the total CO2 emissions in Germany in 2009. While solar heating and cooling today makes a modest contribution to world energy demand, the roadmap envisages that if concerted action is taken by governments and industry, solar energy could annually produce more than 16% of total final energy use for low temperature heat and nearly 17% for cooling. Given that global energy demand for heat represents almost half of the world's final energy use -- more than the combined global demand for electricity and transport -- solar heat can make a significant contribution in both tackling climate change and strengthening energy security.

  5. Bubble heating in Extreme Cooling Clusters

    Science.gov (United States)

    Allen, Steven

    2007-09-01

    Our proposal targets `extreme cooling' clusters: those systems with the largest, fastest cooling rates that most severely challenge the AGN-heating paradigm for cluster cores. By targeting two X-ray bright `extreme cooling cluters' with the clearest radio bubbles in their cores, we seek to establish whether it is possible for AGN heating to balance cooling in such systems. If cooling is not balanced by some heat source, then large residual cooling rates should be detectable in the spectral X-ray data. We will measure the bubble properties precisely and map the spatial-spectral structure of the surrounding X-ray gas, searching for ghost bubbles, shocks, ripples, fronts and non-thermal emission.

  6. COMPARISON OF COOLING SCHEMES FOR HIGH HEAT FLUX COMPONENTS COOLING IN FUSION REACTORS

    Directory of Open Access Journals (Sweden)

    Phani Kumar Domalapally

    2015-04-01

    Full Text Available Some components of the fusion reactor receives high heat fluxes either during the startup and shutdown or during the operation of the machine. This paper analyzes different ways of enhancing heat transfer using helium and water for cooling of these high heat flux components and then conclusions are drawn to decide the best choice of coolant, for usage in near and long term applications.

  7. Cooling and heating of crystalline ion beams

    CERN Document Server

    Schramm, U; Bussmann, M; Habs, D

    2003-01-01

    The crystallization of ion beams has recently been established in the rf quadrupole storage ring PALLAS (PAul Laser CooLing Acceleration System) for laser-cooled sup 2 sup 4 Mg sup + ion beams at an energy of about 1 eV. Yet, unexpectedly sharp constraints had to be met concerning the confinement strength and the longitudinal laser cooling rate. In this paper, related and up to now unseen heating mechanisms are pinpointed for crystalline beams. The weak but inevitable diffusive transverse heating associated with the laser cooling process itself is investigated, possibly allowing the future measurement of the latent heat of the ion crystal. As a function of the beam velocity, the influence of bending shear on the attainability of larger crystalline structures is presented. Finally, rf heating of crystalline beams of different structure is studied for discontinuous cooling.

  8. Thermodynamics of Flow Boiling Heat Transfer

    Science.gov (United States)

    Collado, F. J.

    2003-05-01

    Convective boiling in sub-cooled water flowing through a heated channel is essential in many engineering applications where high heat flux needs to be accommodated. It has been customary to represent the heat transfer by the boiling curve, which shows the heat flux versus the wall-minus-saturation temperature difference. However it is a rather complicated problem, and recent revisions of two-phase flow and heat transfer note that calculated values of boiling heat transfer coefficients present many uncertainties. Quite recently, the author has shown that the average thermal gap in the heated channel (the wall temperature minus the average temperature of the coolant) was tightly connected with the thermodynamic efficiency of a theoretical reversible engine placed in this thermal gap. In this work, whereas this correlation is checked again with data taken by General Electric (task III) for water at high pressure, a possible connection between this wall efficiency and the reversible-work theorem is explored.

  9. Prototype solar heating and combined heating cooling systems

    Science.gov (United States)

    1978-01-01

    The design and development of eight prototype solar heating and combined heating and cooling systems is discussed. The program management and systems engineering are reported, and operational test sites are identified.

  10. CO2在超临界区管内冷却的换热关联式%Heat Transfer Correlations for In-tube Cooling of Supercritical CO2

    Institute of Scientific and Technical Information of China (English)

    周子成

    2015-01-01

    自然制冷剂CO2 的应用日益广泛, 尤其是在跨临界循环的热泵热水器中. 本文综述了超临界CO2 在管内冷却传热关联式的比较和验证.%The natural refrigerant CO2 is used widely, especially in trans -critical cycle heat pump water heat-ers. In this paper, the comparison and validation of heat transfer correlations for in-tube cooling of supercritical CO2 is discussed.

  11. Geothermal Heat Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Basmajian, V.V.

    1986-01-28

    This patent describes a heat transfer apparatus which consists of: heat exchanging means for orientation in the earth below ground substantially vertically, having a hollow conduit of length from top to bottom much greater than the span across the hollow conduit orthogonal to its length with a top, bottom and an intermediate portion contiguous and communicating with the top and bottom portions for allowing thermally conductive fluid to flow freely between the top, intermediate and bottom portions for immersion in thermally conductive fluid in the region around the heat exchanging means for increasing the heat flow between the latter and earth when inserted into a substantially vertical borehole in the earth with the top portion above the bottom portion. The heat exchanger consists of heat exchanging conduit means in the intermediate portion for carrying refrigerant. The heat exchanging conduit consisting of tubes of thermally conductive material for carrying the refrigerant and extending along the length of the hollow conduit for a tube length that is less than the length of the hollow conduit. The hollow conduit is formed with port means between the top and the plurality of tubes for allowing the thermally conductive fluid to pass in a flow path embracing the tubes, the bottom portion, an outer channel around the hollow conduit and the port means.

  12. Cooling apparatus with a resilient heat conducting member

    Energy Technology Data Exchange (ETDEWEB)

    Chainer, Timothy J.; Parida, Pritish R.; Schultz, Mark D.

    2016-06-14

    A cooling structure including a thermally conducting central element having a channel formed therein, the channel being configured for flow of cooling fluid there through, a first pressure plate, and a first thermally conductive resilient member disposed between the thermally conducting central element and the first pressure plate, wherein the first pressure plate, the first thermally conductive resilient member, and the thermally conducting central element form a first heat transfer path.

  13. Homogenization of some radiative heat transfer models: application to gas-cooled reactor cores; Homogeneisation de modeles de transferts thermiques et radiatifs: application au coeur des reacteurs a caloporteur gaz

    Energy Technology Data Exchange (ETDEWEB)

    El Ganaoui, K

    2006-09-15

    In the context of homogenization theory we treat some heat transfer problems involving unusual (according to the homogenization) boundary conditions. These problems are defined in a solid periodic perforated domain where two scales (macroscopic and microscopic) are to be taken into account and describe heat transfer by conduction in the solid and by radiation on the wall of each hole. Two kinds of radiation are considered: radiation in an infinite medium (non-linear problem) and radiation in cavity with grey-diffuse walls (non-linear and non-local problem). The derived homogenized models are conduction problems with an effective conductivity which depend on the considered radiation. Thus we introduce a framework (homogenization and validation) based on mathematical justification using the two-scale convergence method and numerical validation by simulations using the computer code CAST3M. This study, performed for gas cooled reactors cores, can be extended to other perforated domains involving the considered heat transfer phenomena. (author)

  14. Annual DOE active solar heating and cooling contractors' review meeting. Premeeting proceedings and project summaries

    Energy Technology Data Exchange (ETDEWEB)

    None,

    1981-09-01

    Ninety-three project summaries are presented which discuss the following aspects of active solar heating and cooling: Rankine solar cooling systems; absorption solar cooling systems; desiccant solar cooling systems; solar heat pump systems; solar hot water systems; special projects (such as the National Solar Data Network, hybrid solar thermal/photovoltaic applications, and heat transfer and water migration in soils); administrative/management support; and solar collector, storage, controls, analysis, and materials technology. (LEW)

  15. Cooling Load Estimation in the Building Based On Heat Sources

    Science.gov (United States)

    Chairani; Sulistyo, S.; Widyawan

    2017-05-01

    Heating, ventilation and air conditioning (HVAC) is the largest source of energy consumption. In this research, we discuss cooling load in the room by considering the different heat source and the number of occupancy. Energy cooling load is affected by external and internal heat sources. External cooling load in this discussion include convection outdoor/exterior using the DOE-2 algorithm, calculation of heat using Thermal Analysis Research Program (TARP), and Conduction Transfer Function (CTF). The internal cooling load is calculated based on the activity of the occupants in the office, a number of occupants, heat gain from lighting, and heat gain from electrics equipment. Weather data used is Surakarta weather and design day used is Jakarta design day. We use the ASHRAE standard for building materials and the metabolic of occupants while on the activity. The results show that the number of occupancies have an influence of cooling load. A large number of occupancy will cause the cooling load is great as well.

  16. Nucleate boiling heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Saiz Jabardo, J.M. [Universidade da Coruna (Spain). Escola Politecnica Superior], e-mail: mjabardo@cdf.udc.es

    2009-07-01

    Nucleate boiling heat transfer has been intensely studied during the last 70 years. However boiling remains a science to be understood and equated. In other words, using the definition given by Boulding, it is an 'insecure science'. It would be pretentious of the part of the author to explore all the nuances that the title of the paper suggests in a single conference paper. Instead the paper will focus on one interesting aspect such as the effect of the surface microstructure on nucleate boiling heat transfer. A summary of a chronological literature survey is done followed by an analysis of the results of an experimental investigation of boiling on tubes of different materials and surface roughness. The effect of the surface roughness is performed through data from the boiling of refrigerants R-134a and R-123, medium and low pressure refrigerants, respectively. In order to investigate the extent to which the surface roughness affects boiling heat transfer, very rough surfaces (4.6 {mu}m and 10.5 {mu}m ) have been tested. Though most of the data confirm previous literature trends, the very rough surfaces present a peculiar behaviour with respect to that of the smoother surfaces (Ra<3.0 {mu}m). (author)

  17. Model Calculation of Heat Transfer Coefficient of Quenched Cooling under Jet Impingment Plate%厚板射流冲击下淬火冷却的换热系数建模计算

    Institute of Scientific and Technical Information of China (English)

    邓运来; 贺有为; 曹盛强; 张新明

    2011-01-01

    建立一种多喷嘴同时喷射淬火冷却的数学模型,通过实测冷却曲线分析计算厚板驻点区与紊流区换热系数分布规律,基于ABAQUS模拟软件模拟验证模型.结果表明:驻点与紊流点处的换热系数随时间分布是不均匀的,在10~20s内出现峰值,随后呈上下波动变化的规律;实测(或计算)试样心部与表面的冷却曲线与模拟的吻合较好,验证了多喷嘴同时喷射下的换热系数分布模型.%The quenched cooling heat transfer process of the thick plate by multi-nozzle jet impinging is extremely complicated, thus it is difficult to establish a model of the surface heat transfer coefficient distribution, which reveals the speed of the heat transfer on the jet impinging surface. In this paper, the mathematical model of multi-nozzle jet simultaneously impinging quenched cooling has been established, coefficient distribution law at the stagnation and turbulent zone has been calculated by actual measurement of the cooling curve and has been verified based on the ABAQUS simulation software. The results show that the coefficient distribution at the stagnation and turbulent zone is uneven over time, and the peak appeared within 10 to 20 seconds, and then comes to the variation of the next waves. The actual measurement(or calculation) of the cooling curves at the sample' s center and surface is at a very good match state with that of simulation, therefore it verifies the heat transfer coefficient distribution model under the multi-nozzle jet simultaneously impinging.

  18. Elements of heat transfer

    CERN Document Server

    Rathakrishnan, Ethirajan

    2012-01-01

    1 Basic Concepts and Definitions1.1 Introduction1.1.1 Driving Potential1.2 Dimensions and Units1.2.1 Dimensional Homogeneity1.3 Closed and Open Systems1.3.1 Closed System (ControlMass)1.3.2 Isolated System1.3.3 Open System (ControlVolume)1.4 Forms of Energy1.4.1 Internal Energy1.5 Properties of a System1.5.1 Intensive and Extensive Properties1.6 State and Equilibrium1.7 Thermal and Calorical Properties1.7.1 Specific Heat of an Incompressible Substance1.7.2 Thermally Perfect Gas 1.8 The Perfect Gas1.9 Summary1.10 Exercise ProblemsConduction Heat Transfer2.1 Introduction2.2 Conduction Heat Trans

  19. Advances in Solar Heating and Cooling Systems

    Science.gov (United States)

    Ward, Dan S.

    1976-01-01

    Reports on technological advancements in the fields of solar collectors, thermal storage systems, and solar heating and cooling systems. Diagrams aid in the understanding of the thermodynamics of the systems. (CP)

  20. Measuring of heat transfer coefficient

    DEFF Research Database (Denmark)

    Henningsen, Poul; Lindegren, Maria

    Subtask 3.4 Measuring of heat transfer coefficient Subtask 3.4.1 Design and setting up of tests to measure heat transfer coefficient Objective: Complementary testing methods together with the relevant experimental equipment are to be designed by the two partners involved in order to measure...... the heat transfer coefficient for a wide range of interface conditions in hot and warm forging processes. Subtask 3.4.2 Measurement of heat transfer coefficient The objective of subtask 3.4.2 is to determine heat transfer values for different interface conditions reflecting those typically operating in hot...

  1. Measuring of heat transfer coefficient

    DEFF Research Database (Denmark)

    Henningsen, Poul; Lindegren, Maria

    Subtask 3.4 Measuring of heat transfer coefficient Subtask 3.4.1 Design and setting up of tests to measure heat transfer coefficient Objective: Complementary testing methods together with the relevant experimental equipment are to be designed by the two partners involved in order to measure...... the heat transfer coefficient for a wide range of interface conditions in hot and warm forging processes. Subtask 3.4.2 Measurement of heat transfer coefficient The objective of subtask 3.4.2 is to determine heat transfer values for different interface conditions reflecting those typically operating in hot...

  2. 区域供能地下敷设输配管网传热分析方法%Heat transfer analysis of buried pipes in district heating and cooling system

    Institute of Scientific and Technical Information of China (English)

    衣健光

    2014-01-01

    地下敷设是区域供能输配管网的主要敷设方式,其传热计算用于确定保温层厚度、输配管网附加负荷、热损坏可能性。分析了影响地下敷设管网传热的因素,包括:流体与土壤之间的温差、管道的保温隔热性能、埋深、土壤导热系数以及相邻管道之间的间距。介绍了基于热阻的简化稳态计算方法,该方法极大地简化了计算工作量,且计算结果能够满足工程需要,同时该方法适用于大多数地下敷设管网的形式,可供工程设计人员参考。%Buried pipe network is the main way of distribution system in district heating and cooling systems,and its heat transfer calculation is used to determine the thickness of the insulation layer,accessory load of distribution system,and the possibility of thermal damage.Analyses the factors that influence the heat transfer calculation of buried pipe network,including temperature difference between fluid and soil, pipe insulation properties,depth,soil thermal conductivity and distance between adjacent pipes.Present the steady-state thermal calculation method based on thermal resistance formulations,which greatly simplifies the computational effort,and the calculated results can meet project needs.This method is suitable for the majority types of buried pipe network,so it can be used as reference for engineering design.

  3. Natural convective heat transfer from square cylinder

    Science.gov (United States)

    Novomestský, Marcel; Smatanová, Helena; Kapjor, Andrej

    2016-06-01

    This article is concerned with natural convective heat transfer from square cylinder mounted on a plane adiabatic base, the cylinders having an exposed cylinder surface according to different horizontal angle. The cylinder receives heat from a radiating heater which results in a buoyant flow. There are many industrial applications, including refrigeration, ventilation and the cooling of electrical components, for which the present study may be applicable

  4. Van der Waals Force Assisted Heat Transfer

    Science.gov (United States)

    Sasihithlu, K.; Pendry, J. B.; Craster, R. V.

    2017-02-01

    Phonons (collective atomic vibrations in solids) are more effective in transporting heat than photons. This is the reason why the conduction mode of heat transport in nonmetals (mediated by phonons) is dominant compared to the radiation mode of heat transport (mediated by photons). However, since phonons are unable to traverse a vacuum gap (unlike photons), it is commonly believed that two bodies separated by a gap cannot exchange heat via phonons. Recently, a mechanism was proposed [J. B. Pendry, K. Sasihithlu, and R. V. Craster, Phys. Rev. B 94, 075414 (2016)] by which phonons can transport heat across a vacuum gap - through the Van der Waals interaction between two bodies with gap less than the wavelength of light. Such heat transfer mechanisms are highly relevant for heating (and cooling) of nanostructures; the heating of the flying heads in magnetic storage disks is a case in point. Here, the theoretical derivation for modelling phonon transmission is revisited and extended to the case of two bodies made of different materials separated by a vacuum gap. Magnitudes of phonon transmission, and hence the heat transfer, for commonly used materials in the micro- and nano-electromechanical industry are calculated and compared with the calculation of conduction heat transfer through air for small gaps as well as the heat transfer calculation due to photon exchange.

  5. Multilead, Vaporization-Cooled Soldering Heat Sink

    Science.gov (United States)

    Rice, John

    1995-01-01

    Vaporization-cooled heat sink proposed for use during soldering of multiple electrical leads of packaged electronic devices to circuit boards. Heat sink includes compliant wicks held in grooves on edges of metal fixture. Wicks saturated with water. Prevents excessive increases in temperature at entrances of leads into package.

  6. Radiant Heating and Cooling Systems. Part two

    DEFF Research Database (Denmark)

    Kim, Kwan Woo; Olesen, Bjarne W.

    2015-01-01

    Control of the heating and cooling system needs to be able to maintain the indoor temperatures within the comfort range under the varying internal loads and external climates. To maintain a stable thermal environment, the control system needs to maintain the balance between the heat gain...

  7. Waste-Heat-Driven Cooling Using Complex Compound Sorbents

    Science.gov (United States)

    Rocketfeller, Uwe; Kirol, Lance; Khalili, Kaveh

    2004-01-01

    Improved complex-compound sorption pumps are undergoing development for use as prime movers in heat-pump systems for cooling and dehumidification of habitats for humans on the Moon and for residential and commercial cooling on Earth. Among the advantages of sorption heat-pump systems are that they contain no moving parts except for check valves and they can be driven by heat from diverse sources: examples include waste heat from generation of electric power, solar heat, or heat from combustion of natural gas. The use of complex compound sorbents in cooling cycles is not new in itself: Marketing of residential refrigerators using SrCl2 was attempted in the 1920s and 30s and was abandoned because heat- and mass-transfer rates of the sorbents were too low. Addressing the issue that gave rise to the prior abandonment of complex compound sorption heat pumps, the primary accomplishment of the present development program thus far has been the characterization of many candidate sorption media, leading to large increases in achievable heat- and mass-transfer rates. In particular, two complex compounds (called "CC260-1260" and "CC260-2000") were found to be capable of functioning over the temperature range of interest for the lunar-habitat application and to offer heat- and mass-transfer rates and a temperature-lift capability adequate for that application. Regarding the temperature range: A heat pump based on either of these compounds is capable of providing a 95-K lift from a habitable temperature to a heat-rejection (radiator) temperature when driven by waste heat at an input temperature .500 K. Regarding the heat- and mass-transfer rates or, more precisely, the power densities made possible by these rates: Power densities observed in tests were 0.3 kilowatt of cooling per kilogram of sorbent and 2 kilowatts of heating per kilogram of sorbent. A prototype 1-kilowatt heat pump based on CC260-2000 has been built and demonstrated to function successfully.

  8. Preliminary Analysis on Heat Removal Capacity of Passive Air-Water Combined Cooling Heat Exchanger Using MARS

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung-Sin; Jeon, Seong-Su; Hong, Soon-Joon [FNC Tech, Yongin (Korea, Republic of); Bae, Sung-Won; Kwon, Tae-Soon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    Current design requirement for working time of PAFS heat exchanger is about 8 hours. Thus, it is not satisfied with the required cooling capability for the long term SBO(Station Black-Out) situation that is required to over 72 hours cooling. Therefore PAFS is needed to change of design for 72 hours cooling. In order to acquirement of long terms cooling using PAFS, heat exchanger tube has to be submerged in water tank for long time. However, water in the tank is evaporated by transferred heat from heat exchanger tubes, so water level is gradually lowered as time goes on. The heat removal capacity of air cooling heat exchanger is core parameter that is used for decision of applicability on passive air-water combined cooling system using PAFS in long term cooling. In this study, the development of MARS input model and plant accident analysis are performed for the prediction of the heat removal capacity of air cooling heat exchanger. From analysis result, it is known that inflow air velocity is the decisive factor of the heat removal capacity and predicted air velocity is lower than required air velocity. But present heat transfer model and predicted air velocity have uncertainty. So, if changed design of PAFS that has over 4.6 kW heat removal capacity in each tube, this type heat exchanger can be applied to long term cooling of the nuclear power plant.

  9. 46 CFR 56.85-5 - Heating and cooling method.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Heating and cooling method. 56.85-5 Section 56.85-5... APPURTENANCES Heat Treatment of Welds § 56.85-5 Heating and cooling method. Heat treatment may be accomplished by a suitable heating method that will provide the desired heating and cooling rates, the...

  10. 46 CFR 72.20-50 - Heating and cooling.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Heating and cooling. 72.20-50 Section 72.20-50 Shipping... Accommodations for Officers and Crew § 72.20-50 Heating and cooling. (a) All manned spaces must be adequately heated and cooled in a manner suitable to the purpose of the space. (b) The heating and cooling...

  11. 排尘孔涡轮冷却叶片叶顶流动与传热研究%Tip Flow and Heat Transfer Prediction of Cooling Blade with Dirt Purge Holes

    Institute of Scientific and Technical Information of China (English)

    虞跨海; 杨茜; 岳珠峰

    2012-01-01

    涡轮叶片叶顶排尘孔用于清除冷气中掺杂的尘粒,以保证气膜孔和冲击孔的可靠工作,但排尘孔射流引起叶顶流动和传热问题.采用参数化方法建立有、无排尘孔涡轮冷却叶片几何模型,基于包含叶片主体、主燃气通道和三腔回流式内冷却通道的全局模型,采用流热耦合数值分析,开展排尘孔对涡轮冷却叶片叶顶流动与传热问题的初步研究.研究结果表明,对比有、无排尘孔叶片,排尘孔射流可降低叶顶平均温度约25 K;冷却通道对流换热作用和叶顶排尘孔射流可使叶顶平面降温400~600 K,冷却效果与冷却通道冷气流量和尘孔结构在叶顶位置相关;排尘孔叶顶射流对叶顶间隙高温燃气泄漏具有阻碍作用,可以提高叶片总压恢复系数约0.5%~1.5%,随着冷气流量的增大,这种作用增强;尘孔结构设计应兼顾射流对叶顶流动与传热的共同影响.%Dirty purge holes in the blade tip are used to extract dirt from the coolant flow through centrifugal forces such that these dirt particles do not block small diameter film-cooling holes and injection holes, to ensure safety and reliability of the blade. Whereas, the holes will affect blade tip flow and heat transfer. A numerical study of a turbine blade with dirt purge holes is performed to examine both flow and heat transfer characteristics. Two blade geometry models with and without dirty purge holes are established by a parametric method in CAD software. Coupled aerodynamic and heat transfer numerical simulation is used to predict the blade tip flow and heat transfer, with the integral of the blade solid field, main gas and internal cooling passage flow field. The result shows that, the cool air jet from purge holes can reduce the tip facet average temperature about 25 K, based on the contrast between blades with and without dirty purge holes. Convective heat transfer of internal cooling passage and jet flow of dirty

  12. HEAT TRANSFER ENHANCEMENT OF SMALL SCALE HEAT SINKS USING VIBRATING PIN FIN

    Directory of Open Access Journals (Sweden)

    Suabsakul Gururatana

    2013-01-01

    Full Text Available Heat sinks are widely adopted in electronics cooling together with different technologies to enhance the cooling process. For the small electronics application, the small scale pin fins heat sinks are extensively used to dissipate heat in electronics devices. Due to the limit of space in the small devices, it is impossible to increase heat transfer area. In order to improve the heat transfer performance, the applying the forced vibration is one of challenging method. This study applies the vibration frequency between 50 to 1,000 Hz to pin fins heat sinks. The results of numerical simulation clearly show satisfied heat transfer augmentation. However, the Pressure drop significantly increases with frequency. This phenomenon affects the heat transfer enhancement performance that it increases with frequency until certain value then it drops rapidly. The results of this study can help designing heat sinks for electronics cooling by employing the concept of vibration.

  13. Conduction heat transfer solutions

    Energy Technology Data Exchange (ETDEWEB)

    VanSant, J.H.

    1983-08-01

    This text is a collection of solutions to a variety of heat conduction problems found in numerous publications, such as textbooks, handbooks, journals, reports, etc. Its purpose is to assemble these solutions into one source that can facilitate the search for a particular problem solution. Generally, it is intended to be a handbook on the subject of heat conduction. There are twelve sections of solutions which correspond with the class of problems found in each. Geometry, state, boundary conditions, and other categories are used to classify the problems. Each problem is concisely described by geometry and condition statements, and many times a descriptive sketch is also included. The introduction presents a synopsis on the theory, differential equations, and boundary conditions for conduction heat transfer. Some discussion is given on the use and interpretation of solutions. Supplementary data such as mathematical functions, convection correlations, and thermal properties are included for aiding the user in computing numerical values from the solutions. 155 figs., 92 refs., 9 tabs.

  14. Heat transfer and fire spread

    Science.gov (United States)

    Hal E. Anderson

    1969-01-01

    Experimental testing of a mathematical model showed that radiant heat transfer accounted for no more than 40% of total heat flux required to maintain rate of spread. A reasonable prediction of spread was possible by assuming a horizontal convective heat transfer coefficient when certain fuel and flame characteristics were known. Fuel particle size had a linear relation...

  15. Low temperature heating and high temperature cooling embedded water based surface heating and cooling systems

    CERN Document Server

    Babiak, Jan; Petras, Dusan

    2009-01-01

    This Guidebook describes the systems that use water as heat-carrier and when the heat exchange within the conditioned space is more than 50% radiant. Embedded systems insulated from the main building structure (floor, wall and ceiling) are used in all types of buildings and work with heat carriers at low temperatures for heating and relatively high temperature for cooling.

  16. Heat transfer in a conical porous cylinder with partial heating

    Science.gov (United States)

    Yunus Khan, T. M.; Anjum Badruddin, Irfan; Quadir, G. A.

    2016-09-01

    The current work simulates the heat transfer across a porous medium fixed in an annular conical cylinder. The geometry is such that the lower part is conical annulus supporting a regular annular cylinder. The porous medium is fixed between inner and outer radius of conical annular cylinder. The inner radius until conical section is heated with constant temperature Th whereas the outer radius is cooled to isothermal temperature Tc such that Th>Tc . The heat transfer phenomenon in this case can be described by two coupled partial differential equations which are solved using finite element method by using 3-node triangular elements. The heat transfer characteristics in this case are quite different from other geometries being discussed in the literature. It is observed that the fluid flow is stronger in the conical section as compared to the cylindrical part of porous geometry. A very few isothermal lines penetrate into the cylindrical porous region as compared to that of conical section.

  17. A Compact Remote Heat Transfer Device for Space Cryocoolers

    Science.gov (United States)

    Yan, T.; Zhao, Y.; Liang, T.

    In this paper a compact remote heat transfer device (CRHD) for cryocoolers is proposed. This device is especially attractive in cases where cryocoolers are not easy to set near the heat source, generally the infrared sensor. The CRHD is designed on basis of the concept of loop heat pipes, while the primary evaporator is located near the cryocooler cold head and a simple tube-in-tube secondary evaporator is remotely located and thermally connected with the heat source for cooling. With such a device a cooling power of 1 W is achieved across a heat transfer distance of about 2 m. The major problem of this device is the low heat transfer efficiency (1 W of net cooling power at the cost of about 7 W of cooling power from the cryocooler), and in the future a secondary wicked evaporator will be used instead of the tube-in-tube evaporator in order to improve the efficiency.

  18. Experimental measurement, calculation and thermal visualization condenser temperature of cooling device with a heat pipe technology

    Directory of Open Access Journals (Sweden)

    Nemec Patrik

    2017-01-01

    Full Text Available This work deal with evaluation of condenser temperature by experimental measurement, calculation and thermal visualization of cooling device working with a heat pipe technology. The referred device in the article is cooling device capable transfer high heat fluxes from electric elements to the surrounding. One from many things influenced the heat flux amount transferred from electronic elements through the cooling device to the surrounding is condenser construction, its capacity and option of heat removal. The work contain description, working principle and construction of cooling device. Experimental part describe the measuring method and mathematical calculation to condenser temperature evaluation of cooling device depending on the loaded heat of electronic components in range from 250 to 750 W. The mathematical calculation is based on physical phenomena of boiling, condensation and natural convection heat transfer. The results of experimental measurement and mathematical calculation are verified by thermal imagining of device condenser by IR camera.

  19. Phonon Cooling by an Optomechanical Heat Pump.

    Science.gov (United States)

    Dong, Ying; Bariani, F; Meystre, P

    2015-11-27

    We propose and analyze theoretically a cavity optomechanical analog of a heat pump that uses a polariton fluid to cool mechanical modes coupled to a single precooled phonon mode via external modulation of the substrate of the mechanical resonator. This approach permits us to cool phonon modes of arbitrary frequencies not limited by the cavity-optical field detuning deep into the quantum regime from room temperature.

  20. Heat transfer in rocket combustion chambers

    Science.gov (United States)

    Anderson, P.; Cheng, G.; Farmer, R.

    1993-01-01

    Complexities of liquid rocket engine heat transfer which involve the injector faceplate and film cooled walls are being investigated by computational analysis. A conjugate heat transfer analysis was used to describe localized heating phenomena associated with particular injector configurations and film coolant flows. These components were analyzed, and the analyses verified when appropriate test data were available. The component analyses are being synthesized into an overall flowfield/heat transfer model. A Navier-Stokes flow solver, the FDNS code, was used to make the analyses. Particular attention was given to the representation of the thermodynamic properties of the fluid streams. Unit flow models of specific coaxial injector elements have been developed and are being used to describe the flame structure near the injector faceplate.

  1. Numerical Study of Condensation Heat Exchanger Design in a Cooling jacket: Correlation Investigation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myoung Jun; Lee, Hee Joon [Kookmin Univ., Seoul (Korea, Republic of); Kang, Han Ok; Lee, Tae Ho; Park, Cheon Tae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    In this study, condensing heat transfer correlation of TSCON is evaluated with the existing experimental data set to design condensation heat exchanger without noncondensable gas effect (pure steam condensation) in a cooling jacket. From the investigation of the existing condensation heat transfer correlation to the existing experimental data, the improved Shah's correlation showed most satisfactory result for the condensation heat transfer coefficient with experimental data of Khun in a cooling jacket, whereas the Shah's correlation with experimental data of Lee. Lee et al. reported the improved Shah correlation gave us the best predictor for the condensation heat transfer data of Kim and Henderson in a subcooled and saturated water pool. They suggested the improved Shah correlation should be adopted as condensation heat transfer module in TSCON(Thermal Sizing of CONdenser) to design condensation heat exchanger in secondary passive cooling system of nuclear plant.

  2. Analysis of the heat transfer in double and triple concentric tube heat exchangers

    Science.gov (United States)

    Rădulescu, S.; Negoiţă, L. I.; Onuţu, I.

    2016-08-01

    The tubular heat exchangers (shell and tube heat exchangers and concentric tube heat exchangers) represent an important category of equipment in the petroleum refineries and are used for heating, pre-heating, cooling, condensation and evaporation purposes. The paper presents results of analysis of the heat transfer to cool a petroleum product in two types of concentric tube heat exchangers: double and triple concentric tube heat exchangers. The cooling agent is water. The triple concentric tube heat exchanger is a modified constructive version of double concentric tube heat exchanger by adding an intermediate tube. This intermediate tube improves the heat transfer by increasing the heat area per unit length. The analysis of the heat transfer is made using experimental data obtained during the tests in a double and triple concentric tube heat exchanger. The flow rates of fluids, inlet and outlet temperatures of water and petroleum product are used in determining the performance of both heat exchangers. Principally, for both apparatus are calculated the overall heat transfer coefficients and the heat exchange surfaces. The presented results shows that triple concentric tube heat exchangers provide better heat transfer efficiencies compared to the double concentric tube heat exchangers.

  3. 直接空冷岛顺流基管管内冷凝的传热传质分析%Analysis for Heat and Mass Transfer of Condensation inside Down-Flow Unit Tube of Air Cooled Heat Exchanger

    Institute of Scientific and Technical Information of China (English)

    邓慧; 白焰; 李小缤; 党伟玮; 李欣欣

    2015-01-01

    顺流基管是火电厂直接空冷岛关键部件,分析基管管内传热传质机理,对优化基管传热和空冷岛安全运行有重要意义.考虑基管几何特征和安装倾角,建立模拟蒸汽在基管内壁上冷凝的三维坐标数学模型.求解模型数值解时,假设基管壁温未知,设计迭代算法估算壁温.通过对比蒸汽凝结率数值解与设计值,管内换热系数数值解与Nusselt经验公式值,验证了模型的有效性.对模型数值解进一步分析发现,膜厚偏微分方程能正确描述基管几何特征和倾角影响下的液膜特性,汽液两相分离位置的预测值与直接空冷岛运行实际相符,凝结水过冷度数值解不能完全匹配实际测量值.本文的研究成果,为设计高效换热基管和空冷岛冬季防冻,提供了理论依据.%The down-flow unit tube is a key component of air cooled heat exchanger (ACHE) in power plant. The study on the heat and mass transfer mechanism inside the unit tube is very important for heat-transfer efficiency optimization and safe operation of ACHE. In this paper, considering the geometry characteristics of tube, a 3D mathematical model was constructed to simulate the condensation of steam on the internal wall of unit tube. The temperature of tube wall was assumed to be unknown and an iterative algorithm was developed to evaluate this temperature. The numerical solution of steam condensate rate was compared with design value, and simultaneously, numerical solution of heat transfer coefficient was compared with Nusselt empirical formula value to verify the model validation. Further analysis on the model numerical solution shows that the partial differential equations of condensate film thickness can accurately describe the film characteristic which varies with geometry structure and declination of the tube. And the predicted value of vapour-liquid separation location agrees well with ACHE experimental operation. However, the numerical solution of

  4. Heat transfer physics

    CERN Document Server

    Kaviany, Massoud

    2014-01-01

    This graduate textbook describes atomic-level kinetics (mechanisms and rates) of thermal energy storage, transport (conduction, convection, and radiation), and transformation (various energy conversions) by principal energy carriers. The approach combines the fundamentals of molecular orbitals-potentials, statistical thermodynamics, computational molecular dynamics, quantum energy states, transport theories, solid-state and fluid-state physics, and quantum optics. The textbook presents a unified theory, over fine-structure/molecular-dynamics/Boltzmann/macroscopic length and time scales, of heat transfer kinetics in terms of transition rates and relaxation times, and its modern applications, including nano- and microscale size effects. Numerous examples, illustrations, and homework problems with answers that enhance learning are included. This new edition includes applications in energy conversion (including chemical bond, nuclear, and solar), expanded examples of size effects, inclusion of junction quantum tr...

  5. Solar-powered Rankine heat pump for heating and cooling

    Science.gov (United States)

    Rousseau, J.

    1978-01-01

    The design, operation and performance of a familyy of solar heating and cooling systems are discussed. The systems feature a reversible heat pump operating with R-11 as the working fluid and using a motor-driven centrifugal compressor. In the cooling mode, solar energy provides the heat source for a Rankine power loop. The system is operational with heat source temperatures ranging from 155 to 220 F; the estimated coefficient of performance is 0.7. In the heating mode, the vapor-cycle heat pump processes solar energy collected at low temperatures (40 to 80 F). The speed of the compressor can be adjusted so that the heat pump capacity matches the load, allowing a seasonal coefficient of performance of about 8 to be attained.

  6. Determination of effective heat transport coefficients for wall-cooled packed beds

    NARCIS (Netherlands)

    Borkink, J.G.H.; Borkink, J.G.H.; Westerterp, K.R.

    1992-01-01

    The influence is studied of several assumptions, often made in literature, on the values for the effective radial heat conductivity, wall heat transfer coefficient and overall heat transfer coefficient, as obtained from experiments in wall-cooled packed beds without a chemical reaction. Especially t

  7. Kovar Micro Heat Pipe Substrates for Microelectronic Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Benson, David A.; Burchett, Steven N.; Kravitz, Stanley H.; Robino, Charles V.; Schmidt, Carrie; Tigges, Chris P.

    1999-04-01

    We describe the development of a new technology for cooling microelectronics. This report documents the design, fabrication, and prototype testing of micro scale heat pipes embedded in a flat plate substrate or heat spreader. A thermal model tuned to the test results enables us to describe heat transfer in the prototype, as well as evaluate the use of this technology in other applications. The substrate walls are Kovar alloy, which has a coefficient of thermal expansion close to that of microelectronic die. The prototype designs integrating micro heat pipes with Kovar enhance thermal conductivity by more than a factor of two over that of Kovar alone, thus improving the cooling of micro-electronic die.

  8. Radiant Heating and Cooling Systems. Part one

    DEFF Research Database (Denmark)

    Kim, Kwan Woo; Olesen, Bjarne W.

    2015-01-01

    The use of radiant heating systems has several thousand years of history.1,2 The early stage of radiant system application was for heating purposes, where hot air from flue gas (cooking, fires) was circulated under floors or in walls. After the introduction of plastic piping water-based radiant...... heating and cooling with pipes embedded in room surfaces (floor, wall, and ceiling), the application increased significantly worldwide. Earlier application of radiant heating systems was mainly for residential buildings because of its comfort and free use of floor space without any obstruction from...

  9. Experimental analysis on pressure drop and heat transfer of a terminal fan-coil unit with ice slurry as cooling medium

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-15

    This paper is concerned with the experimental analysis of a standard terminal fan-coil unit with ice slurry as coolant. The ice slurry was produced from an ethylene glycol 10 wt% aqueous solution. The pressure drop measurements are presented as a function of volumetric flow rate, ice concentration and Reynolds number. The experimental friction factors are obtained and discussed. The fan-coil capacity was experimentally determined for chilled water and melting ice slurry with inlet ice fractions around 5, 10, 15 and 20 wt%, considering in each case three different fan rotation velocities. The fan-coil capacity is higher with melting ice slurry than with chilled water by factors between 3.7 and 4.9. The heat transfer analysis realizes that the air side thermal resistance controls the heat transfer process. Experimental results for the melt off rate of ice in the fan coil and the superheating at the fan-coil outlet are shown and discussed. (author)

  10. Liquid cooled plate heat exchanger for battery cooling of an electric vehicle (EV)

    Science.gov (United States)

    Rahman, M. M.; Rahman, H. Y.; Mahlia, T. M. I.; Sheng, J. L. Y.

    2016-03-01

    A liquid cooled plate heat exchanger was designed to improve the battery life of an electric vehicle which suffers from premature aging or degradation due to the heat generation during discharging and charging period. Computational fluid dynamics (CFD) was used as a tool to analyse the temperature distribution when a constant surface heat flux was set at the bottom surface of the battery. Several initial and boundary conditions were set based on the past studies on the plate heat exchanger in the simulation software. The design of the plate heat exchanger was based on the Nissan Leaf battery pack to analyse the temperature patterns. Water at different mass flow rates was used as heat transfer fluid. The analysis revealed the designed plate heat exchanger could maintain the surface temperature within the range of 20 to 40°C which is within the safe operating temperature of the battery.

  11. 间接空气冷凝扩展表面换热器结构优化%Power Plant Cooling System Type Slotted Aluminum Fin Surface Heat Transfer and Flow Resistance Characteristics of Numerical Study

    Institute of Scientific and Technical Information of China (English)

    安恩科; 张浏骏; 冯祥

    2014-01-01

    Because of low cost , easy molding Aluminum finned tube is widely applied in the indirect air -cooling condenser , the relationship between the heat transfer coefficient and resistance on air speed to aluminum finned tube heat exchanger design and operation is very important.Using computational fluid dynamics ( CFD) method, the heat resistance performance on three structures of aluminum fin heat exchangers are studied by numerical simulation , the calculation results show that , for the same diameter , the heat transfer coefficient of single bridge and the double bridge structure is basically the same , but the double bridge resistance increased; for single or double bridge struc-ture, Large diameter has the large heat transfer coefficient , at the same time resistance increases more; when the fin thinning , the heat transfer coefficient is basically unchanged , but the resistance is obviously reduced.The re-search results has an important reference value on the economic operation of the air cooled condenser and air cooling power plant.%铝翅片管由于成本低、易于成型在间接空冷冷凝器上有广泛应用,其传热系数和阻力与空气速度之间的关系对铝翅片管换热器设计和运行很重要。应用计算流体力学(CFD)方法,对三种结构铝翅片换热器的换热及阻力性能进行了数值模拟,计算结果表明,对于相同的管径,单桥与双桥结构的传热系数基本相同,而双桥的阻力有所增大;对于单桥或双桥结构来说,大管结构的传热系数增大,同时阻力增大较多;当翅片减薄时,传热系数基本不变,而阻力有明显的减小。研究结果对提高空冷凝汽器乃至空冷电厂的运行经济性都具有重要的参考价值。

  12. Tubing for augmented heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Yampolsky, J.S.; Pavlics, P.

    1983-08-01

    The objectives of the program reported were: to determine the heat transfer and friction characteristics on the outside of spiral fluted tubing in single phase flow of water, and to assess the relative cost of a heat exchanger constructed with spiral fluted tubing with one using conventional smooth tubing. An application is examined where an isolation water/water heat exchanger was used to transfer the heat from a gaseous diffusion plant to an external system for energy recovery. (LEW)

  13. Ten questions about radiant heating and cooling systems

    DEFF Research Database (Denmark)

    Rhee, Kyu-Nam; Olesen, Bjarne W.; Kim, Kwang Woo

    2017-01-01

    Radiant heating and cooling (RHC) systems are being increasingly applied not only in residential but also in non-residential buildings such as commercial buildings, education facilities, and even large scale buildings such as airport terminals. Furthermore, with the combined ventilation system used...... studies on RHC systems in terms of comfort, heat transfer analysis, energy simulation, control strategy, system configurations and so on. Many studies have demonstrated that the RHC system is a good solution to improve indoor environmental quality while reducing building energy consumption for heating...

  14. Microscale surface modifications for heat transfer enhancement.

    Science.gov (United States)

    Bostanci, Huseyin; Singh, Virendra; Kizito, John P; Rini, Daniel P; Seal, Sudipta; Chow, Louis C

    2013-10-09

    In this experimental study, two surface modification techniques were investigated for their effect on heat transfer enhancement. One of the methods employed the particle (grit) blasting to create microscale indentations, while the other used plasma spray coating to create microscale protrusions on Al 6061 (aluminum alloy 6061) samples. The test surfaces were characterized using scanning electron microscopy (SEM) and confocal scanning laser microscopy. Because of the surface modifications, the actual surface area was increased up to 2.8× compared to the projected base area, and the arithmetic mean roughness value (Ra) was determined to vary from 0.3 μm for the reference smooth surface to 19.5 μm for the modified surfaces. Selected samples with modified surfaces along with the reference smooth surface were then evaluated for their heat transfer performance in spray cooling tests. The cooling system had vapor-atomizing nozzles and used anhydrous ammonia as the coolant in order to achieve heat fluxes up to 500 W/cm(2) representing a thermal management setting for high power systems. Experimental results showed that the microscale surface modifications enhanced heat transfer coefficients up to 76% at 500 W/cm(2) compared to the smooth surface and demonstrated the benefits of these practical surface modification techniques to enhance two-phase heat transfer process.

  15. Unsteady heat transfer during subcooled film boiling

    Science.gov (United States)

    Yagov, V. V.; Zabirov, A. R.; Lexin, M. A.

    2015-11-01

    Cooling of high-temperature bodies in subcooled liquid is of importance for quenching technologies and also for understanding the processes initiating vapor explosion. An analysis of the available experimental information shows that the mechanisms governing heat transfer in these processes are interpreted ambiguously; a more clear-cut definition of the Leidenfrost temperature notion is required. The results of experimental observations (Hewitt, Kenning, and previous investigations performed by the authors of this article) allow us to draw a conclusion that there exists a special mode of intense heat transfer during film boil- ing of highly subcooled liquid. For revealing regularities and mechanisms governing intense transfer of energy in this process, specialists of Moscow Power Engineering Institute's (MPEI) Department of Engineering Thermal Physics conduct systematic works aimed at investigating the cooling of high-temperature balls made of different metals in water with a temperature ranging from 20 to 100°C. It has been determined that the field of temperatures that takes place in balls with a diameter of more than 30 mm in intense cooling modes loses its spherical symmetry. An approximate procedure for solving the inverse thermal conductivity problem for calculating the heat flux density on the ball surface is developed. During film boiling, in which the ball surface temperature is well above the critical level for water, and in which liquid cannot come in direct contact with the wall, the calculated heat fluxes reach 3-7 MW/m2.

  16. Heat transfer anysis for conduction-cooled Peltier current leads%传导冷却珀尔贴电流引线的传热分析

    Institute of Scientific and Technical Information of China (English)

    陈桂新; 王银顺; 皮伟

    2015-01-01

    连接超导装置和外部电源的电流引线,是制冷系统的主要漏热源,决定着超导装置的运行效率。为实现漏热的最小化,对珀尔贴电流引线( Peltier current lead ,简称PCL)进行了传热分析;引入热电参数的温度特性,建立了PCL的二维模型;采用有限元法对传导冷却下的PCL进行漏热分析与结构优化,得到了电流引线的最优几何参数。分析发现引线室温端的漏热大约为低温端的2倍;忽略热电参数的温度特性将使几何参数偏离最佳值,造成额外的制冷负荷。%Current leads , a connecting superconducting devices at cryogenic temperature with power source at room temperature , are the major heat leak source during operation , determining the operating effi-ciency of superconducting devices .With considering its thermoelectric property , a two-dimensional model of the conduction-cooled Peltier current lead ( PCL) was established and optimized in order to achieve the min-imum heat leakage by using finite-element simulation .The results showed that room-temperature heat leak-age was about double of low-temperature one at ends of current leads;the geometric parameters would devi-ate from the optimal value if temperature characteristics of thermoelectric parameters were ignored , which led to extra cooling load .

  17. Impingement heat sinks for air cooled high power electronic modules

    Energy Technology Data Exchange (ETDEWEB)

    Kang, S.S.; Holahan, M.F. [IBM Corp., Rochester, MN (United States)

    1995-12-31

    The subject of the present work is a parallel plate heat sink that is designed so that the air flow impinges at the fin tips and exhausts over the two open side faces. This type of design attempts to achieve an air flow direction that is substantially opposite to the heat flow direction within the fins so as to exploit the greater heat transfer effectiveness of counterflow heat exchange. A one dimensional model of the heat sink was developed with the assumption of air flow from the fin tips to the fin base. This simplified model was used to identify an initial heat sink geometry to cool a specific multichip module. Computational Fluid Dynamics models that account for the actual flow pattern within the heat sink were used to study a range of variations to the initial geometry and to identify the best geometry over the range examined. Experimental heat transfer and pressure drop data is reported for two heat sink prototypes. The test data is in good agreement with CFD predictions. Suitable correlations for the heat sink thermal resistance and pressure drop versus the air flow rate are developed. The developed heat sink demonstrated an area specific thermal resistance better than 8.7 C (W/cm{sup 2}).

  18. Temporal and radial dependent profiles for surface heat transfer during R404a spray cooling%R404a喷雾冷却表面传热特性的时空不均匀性

    Institute of Scientific and Technical Information of China (English)

    王锐; 周致富; 白飞龙; 陈斌; 王国祥

    2015-01-01

    Cryogen spray cooling has been applied to protect epidermis from thermal damage during laser surgery. However, the presently used cryogen, R134a shows unsatisfactory efficacy in minimizing laser energy absorption by melanin in darkly pigmented human skins. Previous work of our group showed that R404a had the potential of improving cooling protection to epidermis, while there is few related research on the surface heat transfer during R404a spray cooling. This paper presents an experimental study on the temporal and radial variation in temperature and heat flux during spray cooling using R404a by a specially designed nozzle with expansion chamber, which significantly improved the atomization effect. The temporal and radial conditions strongly influenced uniformity of surface heat transfer. However, there existed a sub-region of uniform cooling with radius of 2 mm around spray center with high heat flux. The result of this experiment could provide guidance for guaranteeing uniform cooling protection during clinical laser surgery.%制冷剂瞬态喷雾冷却是辅助激光手术治疗皮肤病的重要手段,目前采用的R134a制冷剂不易抵消深色人种表皮中的黑色素对激光能量的大量吸收,采用沸点较低的R404a制冷剂能更有效防止表皮的热损伤。使用带膨胀腔的新型喷嘴搭建了瞬态喷雾冷却实验台,采用薄膜热电偶快速测温技术对R404a瞬态喷雾冷却表面传热特性进行了研究。结果表明,R404喷雾冷却表面传热具有时间和空间的不均匀性,然而在喷雾中心半径2 mm的中心区域内存在高热通量的均匀冷却区域。在实际激光皮肤临床手术中,参考实验结果可保证喷雾冷却对治疗范围内的表皮进行均匀冷保护。

  19. About Variable Speed Heating and Cooling Pumps

    OpenAIRE

    Cătălin Popovici; Jan Ignat

    2009-01-01

    The present work has the purpose of underlying the advantages of variable speed heating and cooling pumps use for the perspective of general and particular pumping costs and efficiency. The study approaches comparisons between constant flow pumps and variable flow pumps in different given situations and comparatively analyses the pumping costs.

  20. Prototype solar heating and cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    1978-03-01

    A collection of quarterly reports from the AiResearch Manufacturing Company covering the period July 12, 1976, through December 31, 1977, is presented. AiResearch Manufacturing Company is developing eight prototype solar heating and cooling systems. This effort calls for the development, manufacture, test, system installation, maintenance, problem resolution, and performance evaluation. The systems are 3, 25 and 75-ton size units.

  1. Solar heating and cooling demonstration project summaries

    Energy Technology Data Exchange (ETDEWEB)

    1978-05-01

    Brief descriptive overviews are presented of the design and operating characteristics of all commercial and Federal residential solar heating and cooling systems and of the structures themselves. Also included are available pictures of the buildings and simplified solar system diagrams. A list of non-Federal residential installations is provided.

  2. Numerical Study on Flow and Heat Transfer Performance of Rectangular Heat Sink with Compound Heat Transfer Enhancement Structures

    Directory of Open Access Journals (Sweden)

    Di Zhang

    2014-04-01

    Full Text Available Modern gas turbine blade is operating at high temperature which requires abundant cooling. Considering both heat transfer rate and pumping power for internal passages, developing efficient cooling passages is of great importance. Ribbed channel has been proved as effective heat transfer enhancement technology for considerable heat transfer characteristics; however, the pressure loss is impressive. Dimple and protrusion are frequently considered as new heat transfer augmentation tools for their low friction loss in recent years. Numerical simulations are adopted to investigate the thermal performance of rectangular channel with compound heat transfer enhancement structures with ribs, dimples, and protrusions. Among all configurations, the nondimensional dimple/protrusion depths are 0.2. The results present the flow structures of all channel configurations. The Nu/Nu0 distributions of channel section are discussed for each case. The pressure penalty f/f0 and the thermal performance TP are also considered as important parameters for heat transfer enhancement. It can be concluded that the optimal structure of the compound heat transfer enhancement structure is rib + protrusion (D = 6 mm + dimple (D = 15 mm.

  3. Heat transfer, thermal control, and heat pipes

    Science.gov (United States)

    Olstad, W. B.

    1980-01-01

    This volume provides information on recent progress in spacecraft thermal control and the supporting disciplines of conduction, thermal radiation, and heat pipe theory and application. Four problem areas are considered: conduction heat transfer, radiation heat transfer, thermal control, and heat pipes. The topics covered include finite-element methodology for transient conduction/forced-convection thermal analysis; effects of surface finish on thermal contact resistance between different materials; mathematical models for wide-band nongray gas radiation in spherical and cylindrical geometries; thermal design, analysis and testing of the Shuttle remote manipulator arm; porous heat pipe; and transient behavior of liquid trap heat-pipe thermal diodes. Also discussed is the thermal design concept for a high-resolution UV spectrometer.

  4. Experimental Study on the Impact of External Geometrical Shape on Free and Forced Convection Time Dependent Average Heat Transfer Coefficient during Cooling Process

    Directory of Open Access Journals (Sweden)

    Sundus Hussein Abd

    2012-01-01

    Full Text Available In this research, an experimental study was conducted to high light the impact of the exterior shape of a cylindrical body on the forced and free convection heat transfer coefficients when the body is hold in the entrance of an air duct. The impact of changing the body location within the air duct and the air speed are also demonstrated. The cylinders were manufactured with circular, triangular and square sections of copper for its high thermal conductivity with appropriate dimensions, while maintaining the surface area of all shapes to be the same. Each cylinder was heated to a certain temperature and put inside the duct at certain locations. The temperature of the cylinder was then monitored. The heat transfer coefficient were then calculated for forced convection for several Reynolds number (4555-18222.The study covered free convection impact for values of Rayleigh number ranging between (1069-3321. Imperical relationships were obtained for all cases of forced and free convection and compared with equations of circular cylindrical shapes found in literature. These imperical equations were found to be in good comparison with that of other sources.

  5. Porous media heat transfer for injection molding

    Energy Technology Data Exchange (ETDEWEB)

    Beer, Neil Reginald

    2016-05-31

    The cooling of injection molded plastic is targeted. Coolant flows into a porous medium disposed within an injection molding component via a porous medium inlet. The porous medium is thermally coupled to a mold cavity configured to receive injected liquid plastic. The porous medium beneficially allows for an increased rate of heat transfer from the injected liquid plastic to the coolant and provides additional structural support over a hollow cooling well. When the temperature of the injected liquid plastic falls below a solidifying temperature threshold, the molded component is ejected and collected.

  6. Effect of roughness geometry on heat transfer and friction characteristics of PCM storage unit for night coolness storage in summer season

    Directory of Open Access Journals (Sweden)

    Shukla Shailndra Kumar

    2013-01-01

    Full Text Available This paper presents a theoretical analysis of thermal storage unit using phase change material (PCM as storage medium. Storage unit consists of parallel rectangular channels for the air flow which are separated by phase change storage material. The purpose of storage unit is to absorb the night coolness and to provide cooled air at comfort temperature during day time in summer season. MATLsimulation tool has been used to compute the air temperature variation with location as well as time, charging and discharging time of storage unit. Phase change material used for analysis is selected in such a way that it’s Melting point lies between comfort temperature and minimum night ambient temperatures. The air flow rate needed for charging of PCM is approximately four times greater than the flow rate required during day time to achieve comfort temperature for approximately eight hours, due to limited summer night time (only eight hours. The length of storage unit for which NTU value is greater than or equal to five will give the exit air temperature equal to PCM temperature for the case of latent heat utilization. It is found that artificial roughness on the duct surface effectively reduces the length of storage unit in the cost of some extra pressure drop across the duct.

  7. Heat transfer model for quenching by submerging

    Energy Technology Data Exchange (ETDEWEB)

    Passarella, D N; Varas, F [Departamento de Matematica Aplicada II, E.T.S. de Ing. de Telecomunicacion, Universidad de Vigo, Campus Marcosende, 36310 Vigo (Spain); MartIn, E B, E-mail: diego@dma.uvigo.es, E-mail: fvaras@uvigo.es, E-mail: emortega@uvigo.es [Area de Mecanica de Fluidos, E.T.S. de Ing. Industriales, Universidad de Vigo, Campus Marcosende, 36310 Vigo (Spain)

    2011-05-01

    In quenching by submerging the workpiece is cooled due to vaporization, convective flow and interaction of both mechanisms. The dynamics of these phenomena is very complex and the corresponding heat fluxes are strongly dependent on local flow variables such as velocity of fluid and vapor fraction. This local dependence may produce very different cooling rates along the piece, responsible for inappropriate metallurgical transformations, variability of material properties and residual stresses. In order to obtain an accurate description of cooling during quenching, a mathematical model of heat transfer is presented here. The model is based on the drift-flux mixture-model for multiphase flows, including an equation of conservation of energy for the liquid phase and specific boundary conditions that account for evaporation and presence of vapor phase on the surface of the piece. The model was implemented on Comsol Multiphysics software. Generation of appropriate initial and boundary conditions, as well as numerical resolution details, is briefly discussed. To test the model, a simple flow condition was analyzed. The effect of vapor fraction on heat transfer is assessed. The presence of the typical vapor blanket and its collapse can be recovered by the model, and its effect on the cooling rates on different parts of the piece is analyzed. Comparisons between numerical results and data from literature are made.

  8. Heat-stop structure design with high cooling efficiency for large ground-based solar telescope.

    Science.gov (United States)

    Liu, Yangyi; Gu, Naiting; Rao, Changhui; Li, Cheng

    2015-07-20

    A heat-stop is one of the most important thermal control devices for a large ground-based solar telescope. For controlling the internal seeing effect, the temperature difference between the heat-stop and the ambient environment needs to be reduced, and a heat-stop with high cooling efficiency is required. In this paper, a novel design concept for the heat-stop, in which a multichannel loop cooling system is utilized to obtain higher cooling efficiency, is proposed. To validate the design, we analyze and compare the cooling efficiency for the multichannel and existing single-channel loop cooling system under the same conditions. Comparative results show that the new design obviously enhances the cooling efficiency of the heat-stop, and the novel design based on the multichannel loop cooling system is obviously better than the existing design by increasing the thermal transfer coefficient.

  9. Mold Heating and Cooling Pump Package Operator Interface Controls Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Josh A. Salmond

    2009-08-07

    The modernization of the Mold Heating and Cooling Pump Package Operator Interface (MHC PP OI) consisted of upgrading the antiquated single board computer with a proprietary operating system to off-the-shelf hardware and off-the-shelf software with customizable software options. The pump package is the machine interface between a central heating and cooling system that pumps heat transfer fluid through an injection or compression mold base on a local plastic molding machine. The operator interface provides the intelligent means of controlling this pumping process. Strict temperature control of a mold allows the production of high quality parts with tight tolerances and low residual stresses. The products fabricated are used on multiple programs.

  10. Coupled heat transfer analysis of air cooling gas turbine%气冷涡轮气热耦合数值模拟

    Institute of Scientific and Technical Information of China (English)

    周驰; 王强; 郭兆元; 黄家骅; 冯国泰

    2009-01-01

    应用有限差分方法进行气冷涡轮气热耦合计算,研究了影响气热耦合计算精度的几个因素,包括:流场壁面附近的计算网格、湍流转捩模型以及能量方程中普朗特数的计算等.为了能够应用高精度离散格式,并加快计算速度,采用了气热耦合动力学的微分方程与相应的差分格式,采用了结构化网格.数值计算结果与试验进行对比表明,在流场壁面附近应采用正交性好的网格,并在计算中考虑转捩的影响;而普朗特数的变化对本次计算的影响不大.%Coupled heat transfer simulations with a FDM coupled solver were carried out to study the factors effecting the coupled simulation accuracy.Such factors included numerical grids around the blade wall,the turbulence and transition models,and the variation of Pradtl number.The difference scheme corresponding to the conjugate heat transfer dynamics differential equation and structured grids were employed to ensure the computational accuracy and speed.The comparison between numerical results and the measured ones shows that the grids quality around the blade wall and the transition model are essential for the coupled heat transfer simulations,and that the variation of Prandtl number affects slightly on the numerical results.

  11. Heat transfer and pressure drop in flow boiling in microchannels

    CERN Document Server

    Saha, Sujoy Kumar

    2016-01-01

    This Brief addresses the phenomena of heat transfer and pressure drop in flow boiling in micro channels occurring in high heat flux electronic cooling. A companion edition in the Springer Brief Subseries on Thermal Engineering and Applied Science to “Critical Heat Flux in Flow Boiling in Micro channels,” by the same author team, this volume is idea for professionals, researchers and graduate students concerned with electronic cooling.

  12. Cooling of Accretion-Heated Neutron Stars

    Indian Academy of Sciences (India)

    Rudy Wijnands; Nathalie Degenaar; Dany Page

    2017-09-01

    We present a brief, observational review about the study of the cooling behaviour of accretion-heated neutron stars and the inferences about the neutron-star crust and core that have been obtained from these studies. Accretion of matter during outbursts can heat the crust out of thermal equilibrium with the core and after the accretion episodes are over, the crust will cool down until crust-core equilibrium is restored. We discuss the observed properties of the crust cooling sources and what has been learned about the physics of neutron-star crusts. We also briefly discuss those systems that have been observed long after their outbursts were over, i.e, during times when the crust and core are expected to be in thermal equilibrium. The surface temperature is then a direct probe for the core temperature. By comparing the expected temperatures based on estimates of the accretion history of the targets with the observed ones, the physics of neutron-star cores can be investigated. Finally, we discuss similar studies performed for strongly magnetized neutron stars in which the magnetic field might play an important role in the heating and cooling of the neutron stars.

  13. Combat Vehicle Cooling/Heating Design Investigation.

    Science.gov (United States)

    1981-09-01

    Robert E., and Gaudio, Ralph, Jr.; "Application of the Ranque - Hilsch Vortex Tube to Aircrew Cooling Problems" Report AMRL-TR-67-124; Wright-Patterson...3-6 3-5 Vortex Tube System Schematic 3-8 3-6 Expendable Heat Sink System Schematic 3-9 3-7 Absorption Cooling System Schematic 3-10 4-1 Air Cycle...were determined. These concepts included air cycle, vapor compression cycle, positive displacement air cycle, thermoelectric, vortex tube , expendable

  14. Waste heat recovery using looped heat pipes for air cooling

    Energy Technology Data Exchange (ETDEWEB)

    Lamfon, N.J.; Akyurt, M.; Najjar, Y.S.H. (King Abdulaziz Univ., Jeddah (Saudi Arabia). Mechanical Engineering Dept.)

    1994-07-01

    A scheme is described for the recovery of waste heat from stacks of gas turbine engines and the utilization of recovered energy for the cooling of ambient air. Relationships are summarized for the modeling of components of the cooling system. Samples are presented from performance data that is predicted by the model. Effect of size and design of system components, as well as operational variables on system performance, are discussed. It is concluded that the single most significant variable in the design of the looped heat-pipe recovery and utilization system is the geometry of the exhaust pipe of the gas turbine engine. (author)

  15. Non intrusive measurement of the convective heat transfer coefficient

    Energy Technology Data Exchange (ETDEWEB)

    Rebay, M.; Mebarki, G.; Padet, J. [Reims Univ., Reims (France). Faculty of Science, GRESPI Thermomechanical Lab; Arfaoui, A. [Reims Univ., Reims (France). Faculty of Science, GRESPI Thermomechanical Lab; Tunis Univ., Tunis (Tunisia). Faculty of Science, EL MANAR, LETTM; Maad, B.R. [Tunis Univ., Tunis (Tunisia). Faculty of Science, EL MANAR, LETTM

    2010-07-01

    The efficiency of cooling methods in thermal systems such as radiators and heat exchangers must be improved in order to enhance performance. The evaluation of the heat transfer coefficients between a solid and a fluid is necessary for the control and the dimensioning of thermal systems. In this study, the pulsed photothermal method was used to measure the convective heat transfer coefficient on a solid-fluid interface, notably between an air flow and a heated slab mounted on a PVC flat plate. This configuration simulated the electronic air-cooling inside enclosures and racks. The influence of the deflector's inclination angle on the enhancement of heat transfer was investigated using 2 newly developed identification models. The first model was based on a constant heat transfer coefficient during the pulsed experiment, while the second, improved model was based on a variable heat transfer coefficient. The heat transfer coefficient was deduced from the evolution of the transient temperature induced by a sudden deposit of a luminous energy on the front face of the slab. Temperature evolutions were derived by infrared thermography, a camera for cartography and a detector for precise measurement in specific locations. The results show the improvement of measurement accuracies when using a model that considers the temporal evolution of the convective heat transfer coefficient. The deflection of air flow on the upper surface of the heated slab demonstrated better cooling of the slab by the deflection of air flow. 11 refs., 1 tab., 8 figs.

  16. 一种提高喷雾通风冷却塔换热效果的方法%A Method for Improving Heat Transfer in Spray Cooling Tower

    Institute of Scientific and Technical Information of China (English)

    葛海标; 柴才明; 祝易松

    2014-01-01

    Cooling tower is the core equipment in the circulative water system of CDQ and its performance directly influences the power output and water consumption rate in the coke dry quenching system. Problems such as poor heat transfer, serious wall flow and tower body vibration occurred during operation of the spray cooling tower at the coke dry quench-ing system of Masteel. In the paper the basic principle of spray cooling tower was analyzed, a mathematical model was established and numerical simulations were carried out with fluid dynamics calculation software to found out the direct relationship between poor transfer and wall flow. A solution to increase the injecting angle and reduce wall flow by injector hole shrinkage was finally put forward, which effectively improved heat transfer.%冷却塔是干熄焦循环水系统的核心设备,其换热效果直接影响干熄焦发电量和耗水率。马钢干熄焦系统中应用的喷雾通风冷却塔在使用中出现换热效果不佳、壁流严重以及塔体振动等问题。分析了喷雾通风冷却塔的基本原理,建立其物理模型,并使用计算流体力学软件进行数值计算,找出了其换热效果差与壁流有直接的关系。最后提出了一种解决方案,通过对喷嘴缩径提高射流角度,减少了壁流,从而有效地提高了换热效果。

  17. Heat transfer and thermal control

    Science.gov (United States)

    Crosbie, A. L.

    Radiation heat transfer is considered along with conduction heat transfer, heat pipes, and thermal control. Attention is given to the radiative properties of a painted layer containing nonspherical pigment, bidirectional reflectance measurements of specular and diffuse surfaces with a simple spectrometer, the radiative equilibrium in a general plane-parallel environment, and the application of finite-element techniques to the interaction of conduction and radiation in participating medium, a finite-element approach to combined conductive and radiative heat transfer in a planar medium. Heat transfer in irradiated shallow layers of water, an analytical and experimental investigation of temperature distribution in laser heated gases, numerical methods for the analysis of laser annealing of doped semiconductor wafers, and approximate solutions of transient heat conduction in a finite slab are also examined. Consideration is also given to performance testing of a hydrogen heat pipe, heat pipe performance with gravity assist and liquid overfill, vapor chambers for an atmospheric cloud physics laboratory, a prototype heat pipe radiator for the German Direct Broadcasting TV Satellite, free convection in enclosures exposed to compressive heating, and a thermal analysis of a multipurpose furnace for material processing in space.

  18. On some experiments of heat transfer On some experiments of heat transfer

    Directory of Open Access Journals (Sweden)

    M. P. Murgai

    1954-04-01

    Full Text Available This note describes the results of some experiments on the heat transfer, in an earthenware vessel, used for storing and cooling water in the summer season, and depending for its cooling effect on the evaporative loss. This vessel makes a good approach to a human body; all covered with sweat, and lends itself to an alternative method of measurement of the parameters, in the basic equation of the heat balance of the human body. The results obtained are comparable to those of Brunt, got by observations on human beings.

  19. Evaluation of heat transfer enhancement in air-heating collectors

    Energy Technology Data Exchange (ETDEWEB)

    Mattox, D. L.

    1979-06-01

    The present research effort was initiated for the purpose of increasing the thermal efficiency of air heating solar collectors through identification and development of optimum design and operation criteria for solar absorber-to-air heat exchangers. Initially this effort took the form of a solar collector systems analysis to evaluate the impact of various techniques for enhancing the heat transfer between the absorber and air stream on overall thermal performance of the entire solar collector. This systems analysis resulted in the selection of solar collector designs providing ducted cooling air on the absorber shaded side as a base line. A transient heat transfer analysis of a complete solar air heating collector was used to demonstrate that an optimum absorber-to-air heat exchanger design could be provided with several interrupted fin configurations. Additional analyses were performed to establish that the maximum solar collector thermal performance to required pumping power was realized for a Reynolds number range of 1000 to 2000. This Reynolds number range was used to establish a theoretical design limit curve for maximum thermal performance versus required pumping power for all interrupted fin designs as published in the open literature. Heat and momentum transfer empirical relationships were defined for scaling the state-of-the-art high conductance fin designs identified from a compact configuration to the less compact designs needed for solar collectors.

  20. Simplified models for heat transfer in rooms

    Science.gov (United States)

    Graca, Guilherme C. C. Carrilho Da

    Buildings protect their occupants from the outside environment. As a semi-enclosed environment, buildings tend to contain the internally generated heat and air pollutants, as well as the solar and conductive heat gains that can occur in the facade. In the warmer months of the year this generally leads to overheating, creating a need for a cooling system. Ventilation air replaces contaminated air in the building and is often used as the dominant medium for heat transfer between indoor and outdoor environments. The goal of the research presented in this thesis is to develop a better understanding of the important parameters in the performance of ventilation systems and to develop simplified convective heat transfer models. The general approach used in this study seeks to capture the dominant physical processes for these problems with first order accuracy, and develop simple models that show the correct system behavior trends. Dimensional analysis, in conjunction with simple momentum and energy conservation, scaled model experiments and numerical simulations, is used to improve airflow and heat transfer rate predictions in both single and multi room ventilation systems. This study includes the three commonly used room ventilation modes: mixing, displacement and cross-ventilation. A new modeling approach to convective heat transfer between the building and the outside is presented: the concept of equivalent room heat transfer coefficient. The new model quantifies the reduction in heat transfer between ventilation air and internal room surfaces caused by limited thermal capacity and temperature variation of the air for the three modes studied. Particular emphasis is placed on cross-ventilation, and on the development of a simple model to characterize the airflow patterns that occur in this case. The implementation of the models in a building thermal simulation software tool is presented as well as comparisons between model predictions, experimental results and complex

  1. 气膜冷却布置对前缘流动传热的影响%The Influence of Film Cooling Arrangement on Leading Edge Flow and Heat Transfer

    Institute of Scientific and Technical Information of China (English)

    李雪英; 李明飞; 任静; 蒋洪德

    2014-01-01

    透平一级静叶前缘是高温燃气滞止的区域,承受着整个叶片最高的热负荷,是极为重要的冷却部位.本文首先通过压力敏感漆实验得到了前缘在不同布置、吹风比、密度比情况下的绝热气膜冷却有效度分布,结合数值所给出的详细流场和传热信息,深入剖析了前缘气膜冷却的流动传热机制.%The leading edge of the gas turbine first stage nozzle bearing the highest thermal load due to the stagnation of hot gas is believed to be a very important position for cooling.This article measured the distribution of adiabatic film cooling effectiveness at different blowing ratios and density ratios of several leading edge arrangements with pressure sensitive paint technique.With the aid of detailed flow field and heat transfer information provided by CFD,the flow and heat transfer mechanism of leading edge is deeply analyzed.

  2. Heat transfer intensification by increasing vapor flow rate in flat heat pipes

    Science.gov (United States)

    Sprinceana, Silviu; Mihai, Ioan; Beniuga, Marius; Suciu, Cornel

    2015-02-01

    Flat heat pipes have various technical applications, one of the most important being the cooling of electronic components[9]. Their continuous development is due to the fact that these devices permit heat transfer without external energetic contribution. The practical exploitation of flat heat pipes however is limited by the fact that dissipated power can only reach a few hundred watts. The present paper aims to advance a new method for the intensification of convective heat transfer. A centrifugal mini impeller, driven by a turntable which incorporates four permanent magnets was designed. These magnets are put in motion by another rotor, which in its turn includes two permanent magnets and is driven by a mini electrical motor. Rotation of the centrifugal blades generates speed and pressure increase of the cooling agent brought to vapor state within the flat micro heat pipe. It's well known that the liquid suffers biphasic transformations during heat transfer inside the heat pipe. Over the hotspot (the heat source being the electronic component) generated at one end of the heat pipe, convective heat transfer occurs, leading to sudden vaporization of the liquid. Pressures generated by newly formed vapors push them towards the opposite end of the flat heat pipe, where a finned mini heat sink is usually placed. The mini-heat exchanger is air-cooled, thus creating a cold spot, where vapors condensate. The proposed method contributes to vapor flow intensification by increasing their transport speed and thus leading to more intense cooling of the heat pipe.

  3. Heat Transfer Basics and Practice

    CERN Document Server

    Böckh, Peter

    2012-01-01

    The book provides an easy way to understand the fundamentals of heat transfer. The reader will acquire the ability to design and analyze heat exchangers. Without extensive derivation of the fundamentals, the latest correlations for heat transfer coefficients and their application are discussed. The following topics are presented - Steady state and transient heat conduction - Free and forced convection - Finned surfaces - Condensation and boiling - Radiation - Heat exchanger design - Problem-solving After introducing the basic terminology, the reader is made familiar with the different mechanisms of heat transfer. Their practical application is demonstrated in examples, which are available in the Internet as MathCad files for further use. Tables of material properties and formulas for their use in programs are included in the appendix. This book will serve as a valuable resource for both students and engineers in the industry. The author’s experience indicates that students, after 40 lectures and exercises ...

  4. Advances in industrial heat transfer

    CERN Document Server

    Minea, Alina Adriana

    2012-01-01

    Advances in Industrial Heat Transfer presents the basic principles of industrial heat transfer enhancement. Serving as a reference and guide for future research, this book presents a complete approach, from redesigning equipment to the use of nanofluids in industry. Based on the latest methods of the experiment and their interpretation, this book presents a unified conception of the industrial heat transfer process and procedures which will help decrease global energy consumption. Containing both theoretical and practical results, the book uses text, pictures, graphs, and definitions to illust

  5. Optimization of Heat-Sink Cooling Structure in EAST with Hydraulic Expansion Technique%Optimization of Heat-Sink Cooling Structure in EAST with Hydraulic Expansion Technique

    Institute of Scientific and Technical Information of China (English)

    许铁军; 黄生洪; 谢韩; 宋云涛; 张平; 戢翔; 高大明

    2011-01-01

    Considering utilization of the original chromium-bronze material, two processing techniques including hydraulic expansion and high temperature vacuum welding were proposed for the optimization of heat-sink structure in EAST. The heat transfer performance of heat-sink with or without cooling tube was calculated and different types of connection between tube and heat-sink were compared by conducting a special test. It is shown from numerical analysis that the diameter of heat-sink channel can be reduced from 12 mm to 10 mm. Compared with the original sample, the thermal contact resistance between tube and heat-sink for welding sample can reduce the heat transfer performance by 10%, while by 20% for the hydraulic expansion sample. However, the welding technique is more complicated and expensive than hydraulic expansion technique. Both the processing technique and the heat transfer performance of heat-sink prototype should be further considered for the optimization of heat-sink structure in EAST.

  6. Market potential for solar heating and cooling in buildings

    Science.gov (United States)

    1973-01-01

    The use of solar heating and cooling for buildings as a method of conserving fossil fuels is discussed. The residential and commercial end use consumption of energy is tabulated. A survey to project the energy requirements for home and industry heating and cooling is developed. The survey indicates that there is a market potential for solar heating and cooling of buildings. A prediction of three to five billion dollars per year as the potential for solar heating and cooling is made.

  7. Market potential for solar heating and cooling in buildings

    Science.gov (United States)

    1973-01-01

    The use of solar heating and cooling for buildings as a method of conserving fossil fuels is discussed. The residential and commercial end use consumption of energy is tabulated. A survey to project the energy requirements for home and industry heating and cooling is developed. The survey indicates that there is a market potential for solar heating and cooling of buildings. A prediction of three to five billion dollars per year as the potential for solar heating and cooling is made.

  8. Heat transfer coefficient in serpentine coolant passage for CCDTL

    Energy Technology Data Exchange (ETDEWEB)

    Leslie, P.; Wood, R.; Sigler, F.; Shapiro, A.; Rendon, A.

    1998-12-31

    A series of heat transfer experiments were conducted to refine the cooling passage design in the drift tubes of a coupled cavity drift tube linac (CCDTL). The experimental data were then compared to numerical models to derive relationships between heat transfer rates, Reynold`s number, and Prandtl number, over a range of flow rates. Data reduction consisted of axisymmetric finite element modeling where the heat transfer coefficients were modified to match the experimental data. Unfortunately, the derived relationship is valid only for this specific geometry of the test drift tube. Fortunately, the heat transfer rates were much better (approximately 2.5 times) than expected.

  9. Microscale Waste Heat Driven Cooling System

    Science.gov (United States)

    2012-05-02

    to the Inter-Agency Power Group Mechanical Working Group Meeting 2012 about the ammonia-water absorption chiller technology demonstrator developed by...Development and Engineering Center is provided. 15. SUBJECT TERMS absorption ; heat actuated cooling 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...for a Sustainable Future Sustainable Products for a Sustainable Future Acknowledgments US Army - CERDEC Smaller Lighter Co-Generation & Absorption

  10. Cooling Acoustic Transcucer with Heat Pipes

    Science.gov (United States)

    2009-07-19

    pipes. [0013] Most transducer packages involve a stack of active ceramic. A Tonpilz transducer 10 in the prior art, as depicted in FIG. 1...identical or corresponding parts throughout the several views and wherein: [0023] FIG. 1 is a prior art depiction of a Tonpilz transducer design...Distribution is unlimited 20090916027 Attorney Docket No. 97001 COOLING ACOUSTIC TRANSDUCER WITH HEAT PIPES STATEMENT OF GOVERNMENT INTEREST [0001

  11. Sphere Drag and Heat Transfer.

    Science.gov (United States)

    Duan, Zhipeng; He, Boshu; Duan, Yuanyuan

    2015-07-20

    Modelling fluid flows past a body is a general problem in science and engineering. Historical sphere drag and heat transfer data are critically examined. The appropriate drag coefficient is proposed to replace the inertia type definition proposed by Newton. It is found that the appropriate drag coefficient is a desirable dimensionless parameter to describe fluid flow physical behavior so that fluid flow problems can be solved in the simple and intuitive manner. The appropriate drag coefficient is presented graphically, and appears more general and reasonable to reflect the fluid flow physical behavior than the traditional century old drag coefficient diagram. Here we present drag and heat transfer experimental results which indicate that there exists a relationship in nature between the sphere drag and heat transfer. The role played by the heat flux has similar nature as the drag. The appropriate drag coefficient can be related to the Nusselt number. This finding opens new possibilities in predicting heat transfer characteristics by drag data. As heat transfer for flow over a body is inherently complex, the proposed simple means may provide an insight into the mechanism of heat transfer for flow past a body.

  12. Measurement of the convective heat-transfer coefficient

    CERN Document Server

    Conti, Rosaria; Fiordilino, Emilio

    2014-01-01

    We propose an experiment for investigating how objects cool down toward the thermal equilibrium with its surrounding through convection. We describe the time dependence of the temperature difference of the cooling object and the environment with an exponential decay function. By measuring the thermal constant tau, we determine the convective heat-transfer coefficient, which is a characteristic constant of the convection system.

  13. 46 CFR 92.20-50 - Heating and cooling.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Heating and cooling. 92.20-50 Section 92.20-50 Shipping... AND ARRANGEMENT Accommodations for Officers and Crew § 92.20-50 Heating and cooling. (a) All manned... heating and cooling system for accommodations must be capable of maintaining a temperature of 21 °C (70...

  14. Heat and Mass Transfer Processes in Scrubber of Flue Gas Heat Recovery Device

    OpenAIRE

    Veidenbergs, I; Blumberga, D; Vīgants, E; Kozuhars, G

    2010-01-01

    The paper deals with the heat and mass transfer process research in a flue gas heat recovery device, where complicated cooling, evaporation and condensation processes are taking place simultaneously. The analogy between heat and mass transfer is used during the process of analysis. In order to prepare a detailed process analysis based on heat and mass process descriptive equations, as well as the correlation for wet gas parameter calculation, software in the Microsoft Office Excel environment...

  15. Measurement of the heat transfer and the film cooling effectiveness at a film-cooled leading edge of a turbine blade and derivation of a local model. Pt. C: derivation of a local model. Final report; Messung von Waermeuebergang und Filmkuehleffektivitaet im Bereich der filmgekuehlten Vorderkante eines Turbinenschaufelprofils und Ableitung lokaler Modelle. T. C: Ableitung lokaler Modelle. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Schiffer, H.P.; Biba, S.

    1998-03-31

    Today, the heat transfer on a film-cooled leading edge of a high pressure turbine blade is calculated either by simple but inaccurate correlations or highly complex 3-D-simulations of the entire blade flow. The aim of the project was to derive an improved local model of the heat transfer at the leading edge in order to develop new, more precise correlations. This was done in order to minimize the cooling mass flow requirements and therefore to improve the efficiency of gas turbines. A new simple model of the near wall flow at the film cooled leading edge was derived. The model is based on the modification of the well-known turbulent boundary layer flow at a flat plate. This leads to semi-empirical correlations for the prediction of the adiabatic film cooling effectiveness and the heat transfer coefficient. The parameters of these correlations are matched to measurements at a film cooled leading edge model. By applying the correlations, the heat transfer at the leading edge can be predicted sufficiently accurate in dependence on the downstream distance, the blowing ratio and the Reynolds-number. The correlations can be implemented in existing 2-D-methods for the design of a blade cooling configuration. (orig.) [Deutsch] Der Waermeeintrag an einer filmgekuehlten Vorderkante einer Hochdruckturbinenschaufel wird derzeit mittels einfacher, nicht hinreichend genauer Korrelationen oder durch komplexe 3-D-Simulationen der Stroemung berechnet. Ziel des Vorhabens ist es, zur Minimierung des Kuehlungsmassenstroms und damit zur Wirkungsgradverbesserung der Gasturbine ein verbessertes lokales Modell des Waermeuebergangs und genauere Korrelationen herzuleiten. Im Vorhaben wurde ein Modell fuer die wandnahe Stroemung an einer filmgekuehlten Vorderkante entwickelt. Das Modell beruht auf der Modifikation der bekannten turbulenten Grenzschicht an einer ebenen Platte. Die Modellierung fuehrt zu halb-empirischen Korrelationen fuer die adiabate Filmkuehleffektivitaet und dem

  16. Heat-transfer thermal switch

    Science.gov (United States)

    Friedell, M. V.; Anderson, A. J.

    1974-01-01

    Thermal switch maintains temperature of planetary lander, within definite range, by transferring heat. Switch produces relatively large stroke and force, uses minimum electrical power, is lightweight, is vapor pressure actuated, and withstands sterilization temperatures without damage.

  17. Experimental and numerical investigations of internal heat transfer in an innovative trailing edge blade cooling system: stationary and rotation effects, part 2: numerical results

    Science.gov (United States)

    Beniaiche, Ahmed; Ghenaiet, Adel; Carcasci, Carlo; Facchini, Bruno

    2017-02-01

    This paper presents a numerical validation of the aero-thermal study of a 30:1 scaled model reproducing an innovative trailing edge with one row of enlarged pedestals under stationary and rotating conditions. A CFD analysis was performed by means of commercial ANSYS-Fluent modeling the isothermal air flow and using k- ω SST turbulence model and an isothermal air flow for both static and rotating conditions (Ro up to 0.23). The used numerical model is validated first by comparing the numerical velocity profiles distribution results to those obtained experimentally by means of PIV technique for Re = 20,000 and Ro = 0-0.23. The second validation is based on the comparison of the numerical results of the 2D HTC maps over the heated plate to those of TLC experimental data, for a smooth surface for a Reynolds number = 20,000 and 40,000 and Ro = 0-0.23. Two-tip conditions were considered: open tip and closed tip conditions. Results of the average Nusselt number inside the pedestal ducts region are presented too. The obtained results help to predict the flow field visualization and the evaluation of the aero-thermal performance of the studied blade cooling system during the design step.

  18. Numerical study on heat transfer of slot nozzles impinging gas-jet cooling process%带钢镀后喷射冷却过程传热特性的数值研究

    Institute of Scientific and Technical Information of China (English)

    黄军; 武文斐; 张亚竹; 李保卫; 牛德志

    2012-01-01

    Impinging gas-jet cooling is the most important cooling method in a continuous steel strip annealing and galvanizing production. Numerical simulation of a bellow and an array of slot nozzles impinging gas-jet has been performed through the solution of 3D Navier-Stokes equations and energy equation by using the SIMPLE algorithm and a standard k-e turbulence model. The simulation results reveal the characteristics of flow field and temperature field. Heat flux on strip surface distribution characteristics presented slit-like;the average convection heat transfer coefficient is 127.3W/(m2 · K) and strip cooling rate is 12.4℃/s by typical operating conditions. Provide theoretical basis for design of quick cooling system in continuous steel strip annealing and galvanizing production.%喷射气体冷却是带钢连续退火和镀后冷却过程中最重要的冷却方法,利用数值模拟方法对带钢镀后喷射冷却过程中带钢传热特性进行研究,计算结果表明在带钢表面热流密度呈条缝状分布,典型工况下带钢表面平均对流换热系数为127.3W/(m2·K),带钢冷却速度为12.4℃/s.该研究为带钢连续退火机组及镀后快冷系统设计提供理论依据.

  19. Heating Cooling Flows with Weak Shock Waves

    CERN Document Server

    Mathews, W G; Brighenti, F

    2006-01-01

    The discovery of extended, approximately spherical weak shock waves in the hot intercluster gas in Perseus and Virgo has precipitated the notion that these waves may be the primary heating process that explains why so little gas cools to low temperatures. This type of heating has received additional support from recent gasdynamical models. We show here that outward propagating, dissipating waves deposit most of their energy near the center of the cluster atmosphere. Consequently, if the gas is heated by (intermittent) weak shocks for several Gyrs, the gas within 30-50 kpc is heated to temperatures that far exceed observed values. This heating can be avoided if dissipating shocks are sufficiently infrequent or weak so as not to be the primary source of global heating. Local PV and viscous heating associated with newly formed X-ray cavities are likely to be small, which is consistent with the low gas temperatures generally observed near the centers of groups and clusters where the cavities are located.

  20. Feasibility study of the university of Utah TRIGA reactor power upgrade - part II: Thermohydraulics and heat transfer study in respect to cooling system requirements and design

    Directory of Open Access Journals (Sweden)

    Babitz Philip

    2013-01-01

    Full Text Available The thermodynamic conditions of the University of Utah's TRIGA Reactor were simulated using SolidWorks Flow Simulation, Ansys, Fluent and PARET-ANL. The models are developed for the reactor's currently maximum operating power of 90 kW, and a few higher power levels to analyze thermohydraulics and heat transfer aspects in determining a design basis for higher power including the cost estimate. It was found that the natural convection current becomes much more pronounced at higher power levels with vortex shedding also occurring. A departure from nucleate boiling analysis showed that while nucleate boiling begins near 210 kW it remains in this state and does not approach the critical heat flux at powers up to 500 kW. Based on these studies, two upgrades are proposed for extended operation and possibly higher reactor power level. Together with the findings from Part I studies, we conclude that increase of the reactor power is highly feasible yet dependable on its purpose and associated investments.

  1. Heat Transfer Characteristics of SiC-coated Heat Pipe for Passive Decay Heat Removal

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Mo; Kim, In Guk; Jeong, Yeong Shin; Bang, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2014-10-15

    The main concern with the Fukushima accident was the failure of active and passive core cooling systems. The main function of existing passive decay heat removal systems is feeding additional coolant to the reactor core. Thus, an established emergency core cooling system (ECCS) cannot operate properly because of impossible depressurization under the station blackout (SBO) condition. Therefore, a new concept for passive decay heat removal system is required. In this study, an innovative hybrid control rod concept is considered for passive in-core decay heat removal that differs from the existing direct vessel injection core cooling system and passive auxiliary feedwater system (PAFS). The heat transfer between the evaporator and condenser sections occurs by phase change of the working fluid and capillary action induced by wick structures installed on the inner wall of the heat pipe. In this study, a hybrid control rod is developed to take the roles of both neutron absorption and heat removal by combining the functions of a heat pipe and control rod. Previous studies on enhancing the heat removal capacity of heat pipes used nanofluids, self-rewetting fluids, various wick structures and condensers. Many studies have examined the thermal performances of heat pipes using various nanofluids. They concluded that the enhanced thermal performance of the heat pipe using nanofluids is due to nanoparticle deposition on the wick structures. Thus, the wick structure of heat pipes has been modified by nanoparticle deposition to enhance the heat removal capacity. However, previous studies used relatively small heat pipes and narrow ranges of heat loads. The environment of a nuclear reactor is very specific, and the decay heat produced by fission products after shutdown is relatively large. Thus, this study tested a large-scale heat pipe over a wide range of power. The concept of a hybrid heat pipe for an advanced in-core decay heat removal system was introduced for complete

  2. Convective heat transfer and infrared thermography.

    Science.gov (United States)

    Carlomagno, Giovanni M; Astarita, Tommaso; Cardone, Gennaro

    2002-10-01

    Infrared (IR) thermography, because of its two-dimensional and non-intrusive nature, can be exploited in industrial applications as well as in research. This paper deals with measurement of convective heat transfer coefficients (h) in three complex fluid flow configurations that concern the main aspects of both internal and external cooling of turbine engine components: (1) flow in ribbed, or smooth, channels connected by a 180 degrees sharp turn, (2) a jet in cross-flow, and (3) a jet impinging on a wall. The aim of this study was to acquire detailed measurements of h distribution in complex flow configurations related to both internal and external cooling of turbine components. The heated thin foil technique, which involves the detection of surface temperature by means of an IR scanning radiometer, was exploited to measure h. Particle image velocimetry was also used in one of the configurations to precisely determine the velocity field.

  3. Heat Transfer Parametric System Identification

    Science.gov (United States)

    1993-06-01

    Transfer Parametric System Identification 6. AUTHOR(S Parker, Gregory K. 7. PERFORMING ORGANIZATION NAME(S) AND AOORESS(ES) 8. PERFORMING ORGANIZATION...distribution is unlimited. Heat Transfer Parametric System Identification by Gregory K. Parker Lieutenant, United States Navy BS., DeVry Institute of...Modeling Concept ........ ........... 3 2. Lumped Parameter Approach ...... ......... 4 3. Parametric System Identification ....... 4 B. BASIC MODELING

  4. Numerical Simulation of Fluid - Solid Coupling Heat Transfer in Tunnel Kiln Cooling Zone%隧道窑冷却带流-固耦合散热数值模拟

    Institute of Scientific and Technical Information of China (English)

    许宁; 王雪峰; 张柱银; 王君; 黄建军; 肖慧; 郅晓

    2016-01-01

    以某烧结砖隧道窑为研究对象,为获得隧道窑冷却带散热温度场数据,建立了隧道窑窑壁-砖块-流体耦合传热物理模型与数学模型,采用FLUENT流体计算软件对其进行了隧道窑窑壁-砖块-流体耦合传热仿真,获得了窑内整体比较精确直观的温度场分布。仿真的结果表明:风速为5 m/s、孔隙率为0.5以及砖块适当稀码时,隧道窑冷却带降温效果较好,其与隧道窑烧成曲线冷却段吻合也较好,为风速调整、码砖方式和孔隙率的选择提供了理论依据,提高了烧成质量和生产效率。%In order to obtain the cooling temperature ifeld data in the tunnel kiln cooling zone, the tunnel kiln wall bricks-lfuid coupling heat transfer physical model and mathematic model were established, taking a sintered brick tunnel kiln as the research object. The tunnel kiln wall bricks-lfuid coupling heat transfer simulations were performed by commercial software FLUENT, and the overall accurate intuitive temperature ifeld distribution was obtained. The simulation results show: the cooling effect on the tunnel kiln cooling zone is better when the draft speed is 5 m/s, the pore rate is 0.5, and the bricks arrangement is sparse, and that is also agreeable with the tunnel kiln ifring curve’s cooling segment. This information provides a theoretical basis for the adjustment of the draft speed, pore rate and bricks arrangement to improve the quality of bricks ifring and productivity.

  5. Integrated Bulding Heating, Cooling and Ventilation Control

    Science.gov (United States)

    Dong, Bing

    Current research studies show that building heating, cooling and ventilation energy consumption account for nearly 40% of the total building energy use in the U.S. The potential for saving energy through building control systems varies from 5% to 20% based on recent market surveys. In addition, building control affects environmental performances such as thermal, visual, air quality, etc., and occupancy such as working productivity and comfort. Building control has been proven to be important both in design and operation stages. Building control design and operation need consistent and reliable static and dynamic information from multiple resources. Static information includes building geometry, construction and HVAC equipment. Dynamic information includes zone environmental performance, occupancy and outside weather information during operation. At the same time, model-based predicted control can help to optimize energy use while maintaining indoor set-point temperature when occupied. Unfortunately, several issues in the current approach of building control design and operation impede achieving this goal. These issues include: a) dynamic information data such as real-time on-site weather (e.g., temperature, wind speed and solar radiation) and occupancy (number of occupants and occupancy duration in the space) are not readily available; b) a comprehensive building energy model is not fully integrated into advanced control for accuracy and robustness; c) real-time implementation of indoor air temperature control are rare. This dissertation aims to investigate and solve these issues based on an integrated building control approach. This dissertation introduces and illustrates a method for integrated building heating, cooling and ventilation control to reduce energy consumption and maintain indoor temperature set-point, based on the prediction of occupant behavior patterns and weather conditions. Advanced machine learning methods including Adaptive Gaussian Process

  6. 高炉冷却壁非稳态传热热态实验分析%Thermal Trial Analysis on Unsteady Heat Transfer for Blast Furnace Cooling Stave

    Institute of Scientific and Technical Information of China (English)

    焦克新; 张建良; 左海滨; 沈猛; 铁金艳; 李峰光

    2014-01-01

    冷却壁安全工作是保证高炉长寿的基础。通过设计并建造冷却壁热态实验炉,研究了高炉铸铁冷却壁热面无渣皮和有渣皮时的非稳态传热过程,考察了不同炉气温度条件下冷却壁热电偶温度的变化规律。回归得到了炉气在升温阶段、稳定阶段、降温阶段时冷却壁热电偶温度随时间的变化关系式。计算得出了冷却壁热面在有无渣皮条件下的平均热流强度,回归得出了炉气平均对流换热系数随炉温的变化关系。结果表明,冷却壁热面在有渣皮时热电偶温度的变化速率显著低于无渣皮时的变化速率,冷却壁破损的主要原因是冷却壁温度的反复变化和渣皮的频繁脱落而产生的热应力。%BF campaign is of great significance for efficient, sustainable development of iron and steel enterprises. Smooth operation and the service life of the cooling stave is one of the fundamental factors affecting the life of a blast fur-nace, and therefore subject to focus on the stave efficient longevity research. Through design and construction of hot test furnace for cooling stave, unsteady state heat transfer of blast furnace cooling stave was studied under condition of with or without slag crust and changing rules of thermocouple temperature under different furnace temperatures were also ana-lyzed. Changing rules of thermocouple temperature at heating stage, steady stage and cooling stage were obtained by re-gression method. Average heat flux intensity without slag crust was calculated and through regression method convective heat transfer coefficient was obtained. It was concluded that the changing rate of thermocouple temperature which embed-ded in the cooling stave under condition of with slag crust is significantly lower than without slag crust. The damage of cooling stave is mainly due to thermal stress produced by repeatedly change of temperature and frequently production and separation of slag crust

  7. Fundamental principles of heat transfer

    CERN Document Server

    Whitaker, Stephen

    1977-01-01

    Fundamental Principles of Heat Transfer introduces the fundamental concepts of heat transfer: conduction, convection, and radiation. It presents theoretical developments and example and design problems and illustrates the practical applications of fundamental principles. The chapters in this book cover various topics such as one-dimensional and transient heat conduction, energy and turbulent transport, forced convection, thermal radiation, and radiant energy exchange. There are example problems and solutions at the end of every chapter dealing with design problems. This book is a valuable int

  8. Heat transfer enhancement with nanofluids

    CERN Document Server

    Bianco, Vincenzo; Nardini, Sergio; Vafai, Kambiz

    2015-01-01

    Properties of NanofluidSamuel Paolucci and Gianluca PolitiExact Solutions and Their Implications in Anomalous Heat TransferWenhao Li, Chen Yang and Akira NakayamaMechanisms and Models of Thermal Conductivity in NanofluidsSeung-Hyun Lee and Seok Pil JangExperimental Methods for the Characterization of Thermophysical Properties of NanofluidsSergio Bobbo and Laura FedeleNanofluid Forced ConvectionGilles RoyExperimental Study of Convective Heat Transfer in NanofluidsEhsan B. Haghighi, Adi T. Utomo, Andrzej W. Pacek and Björn E. PalmPerformance of Heat Exchangers Using NanofluidsBengt Sundén and Za

  9. Numerical simulation of regeneraive cooling flow and heat transfer with nonequilibrium flow%燃气非平衡流再生冷却流动传热数值模拟

    Institute of Scientific and Technical Information of China (English)

    康玉东; 孙冰

    2011-01-01

    To better predict the regeneratively cooled liquid rocket engine thrust chamber heat transfer. Three dimensional numerical simulation was carried out for hot gas,solid wall and coolant coupled flow and heat transfer. The 9 steps with 6 specices chemical reaction model was used to simulate gas non-equilibrium chemical reactions. The radiative heat transfer was simulated with DO model. The coolant is supercritical hydrogen whose thermophysical properties are varied with both temperature and pressure. The results show that Redlich-Kwong equation of state, Peng-Robinson equation of state, Lucas method, TRAPP method can be used to predict hydrogen density, specific heat at constant pressure, viscosity, thermal conductivity, respectively.The simulated results using non-equilibrium flow are more accordant with real condition.%为准确预测液体火箭发动机推力室身部再生冷却换热状况,采用数值模拟方法,对燃气、推力室壁和超临界气氢进行三维流动和换热耦合计算.采用6组分9步反应动力学模型计算燃气的非平衡化学反应,采用DO模型计算燃气辐射换热,考虑超临界气氢物性随温度和压力的变化.获得了室壁温度场、燃气及冷却剂流场.结果表明,Redlich-Kwong方程、Peng-Robinson方程、Lucas法、TRAPP法能分别准确计算超临界氢的密度、定压比热容、粘度、导热系数,采用燃气非平衡流计算所得流场值更符合实际情况.

  10. 稠密栅堆芯再淹没先驱冷却区域换热模型研究%Study on Heat Transfer Prediction Models of Precursory Cooling Region in Reflooding Phase of Tight Lattice

    Institute of Scientific and Technical Information of China (English)

    吴丹; 余红星

    2012-01-01

    On the basis of the reflooding experiment NEPTUN-LWHCR performed in Switzerland, this paper summarized the characteristics of the reflooding phase of tight lattice, and analyzed the reasons for the high peak clad temperature. A new heat transfer model of precursory cooling is established. It is proposed that the steam cooling is relatively poor in the precursory cooling to make the peak clad temperature higher. Through validating this mew model by calculating the peak clad temperature, it can be concluded that the new model is reasonable.%以瑞士NEPTUN-LWHCR稠密栅堆芯再淹没实验为基础,总结稠密栅再淹没过程的特点,建立先驱冷却换热新模型,分析造成再淹没过程包壳峰值温度较高的原因.分析表明,稠密栅再淹没过程中先驱冷却较差主要原因是蒸汽冷却较差.包壳峰值温度的对比验证了先驱冷却换热新模型的合理性.

  11. Nanofluid impingement jet heat transfer.

    Science.gov (United States)

    Zeitoun, Obida; Ali, Mohamed

    2012-02-17

    Experimental investigation to study the heat transfer between a vertical round alumina-water nanofluid jet and a horizontal circular round surface is carried out. Different jet flow rates, jet nozzle diameters, various circular disk diameters and three nanoparticles concentrations (0, 6.6 and 10%, respectively) are used. The experimental results indicate that using nanofluid as a heat transfer carrier can enhance the heat transfer process. For the same Reynolds number, the experimental data show an increase in the Nusselt numbers as the nanoparticle concentration increases. Size of heating disk diameters shows reverse effect on heat transfer. It is also found that presenting the data in terms of Reynolds number at impingement jet diameter can take into account on both effects of jet heights and nozzle diameter. Presenting the data in terms of Peclet numbers, at fixed impingement nozzle diameter, makes the data less sensitive to the percentage change of the nanoparticle concentrations. Finally, general heat transfer correlation is obtained verses Peclet numbers using nanoparticle concentrations and the nozzle diameter ratio as parameters.

  12. Field evaluation of performance of radiant heating/cooling ceiling panel system

    DEFF Research Database (Denmark)

    Li, Rongling; Yoshidomi, Togo; Ooka, Ryozo;

    2015-01-01

    heating/coolingceiling panel system is used. However, no standard exists for the in situ performance evaluation of radiantheating/cooling ceiling systems; furthermore, no published database is available for comparison. Thus,this study aims to not only clarify the system performance but also to share our...... experience and our resultsfor them to serve as a reference for other similar projects. Here, the system performance in relation toits heating/cooling capacity and thermal comfort has been evaluated. The heat transfer coefficient fromwater to room was 3.7 W/(m2K) and 4.8 W/(m2K) for heating and cooling cases...

  13. Effects of ridged walls on the heat transfer in a heated square duct

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez, M.S.; Rodriguez, W.V. [Ciudad Universitaria, Mexico DF (Mexico). Instituto de Ingenieria, UNAM, Coordinacion de Ingenieria de Procesos Industrails y Ambientales, Circuito Interior; Issa, R. [LEGI-MOST, INPG, Grenoble (France)

    2005-05-01

    Turbulent flows in rectangular cooling ducts of rocket engine thrust chambers are characterized by secondary motions of Prandtl's first and second kinds. These secondary currents play a prominent part in heat transfer between the thrust chamber and the cooling gas conveyed in the duct. Previous numerical and experimental works reveal that attaching ridges on the walls of the duct causes the formation of new secondary flows of Prandtl's second kind. These new structures are likely to increase the heat transfer. The present study has investigated numerically, through large eddy simulations, the effects of different forms of ridges on heat transfer in straight square duct flows. (author)

  14. Nanofluid jet impingement heat transfer characteristics in the rectangular mini-fin heat sink

    Science.gov (United States)

    Naphon, Paisarn; Nakharintr, Lursukd

    2012-11-01

    The nanofluid jet impingement heat transfer characteristics in a rectangular mini-fin heat sink are studied. The heat sink is fabricated from aluminum by a wire electrical discharge machine. The nanofluid is a mixture of deionized water and nanoscale TiO2 particles with a volume nanoparticle concentration of 0.2%. The results obtained for nanofluid jet impingement cooling in the rectangular mini-fin heat sink are compared with those found in the water jet impingement cooling. The effects of the inlet temperature of the nanofluid, its Reynolds number, and the heat flux on the heat transfer characteristics of the rectangular mini-fin heat sink are considered. It is found that the average heat transfer rates for the nanofluid as coolant are higher than those for deionized water.

  15. Thermal design for areas of interference heating on actively cooled hypersonic aircraft

    Science.gov (United States)

    Herring, R. L.; Stone, J. E.

    1978-01-01

    Numerous actively cooled panel design alternatives for application in regions on high speed aircraft that are subject to interference heating effects were studied. Candidate design concepts were evaluated using mass, producibility, reliability and inspectability/maintainability as figures of merit. Three design approaches were identified as superior within certain regimes of the matrix of design heating conditions considered. Only minor modifications to basic actively cooled panel design are required to withstand minor interference heating effects. Designs incorporating internally finned coolant tubes to augment heat transfer are recommended for moderate design heating conditions. At severe heating conditions, an insulated panel concept is required.

  16. Inverted annular flow heat transfer in a natural circulation loop

    Energy Technology Data Exchange (ETDEWEB)

    Ozawa, M.; Umekawa, H.; Shiba, Y.; Yano, T. [Kansai Univ., Osaka (Japan)

    1998-07-01

    Gravity-feed reflooding experiment was conducted in a natural circulation loop of liquid nitrogen. The cooling curve of high temperature tube wall had a characteristic feature, i.e. initial rapid cooling with steam binding, relatively long-time plateau, gradual decrease with or without flow oscillation, and final drastic decrease during quenching process. Such phenomena had close relationship to the heated wall dynamics and heating power transient. To provide fundamental understanding on the present phenomena, the heat transfer data in inverted annular and dispersed flows were obtained under steady or oscillatory flow condition. The experimental data suggested that the heat transfer coefficient in the inverted annular or dispersed flow regimes is a slightly increasing function of heat flux but significantly depended on the tube diameter. The flow oscillation deteriorated heat transfer slightly in the inverted annular and dispersed flow regimes but significantly in the quenching process.

  17. Heat engineering characteristics of the radiator for effective electronic equipment cooling systems

    Directory of Open Access Journals (Sweden)

    Rudenko A. I.

    2011-06-01

    Full Text Available The article presents the results of heat transfer charac-teristics research of the radiator on basis of a heat pipe for cooling of personal computer elements. It is determined that using acetone and ethanol as heat carriers under heat flow density q4·104 W/m2 is preferable. It is shown that the introduced radiators are considerably more effective than the radiators of conventional design with flat heat exchange surface with a rectangle plate fin.

  18. Numerical Model for Conduction-Cooled Current Lead Heat Loads

    CERN Document Server

    White, M J; Brueck, H D; 10.1063/1.4706965

    2012-01-01

    Current leads are utilized to deliver electrical power from a room temperature junction mounted on the vacuum vessel to a superconducting magnet located within the vacuum space of a cryostat. There are many types of current leads used at laboratories throughout the world, however, conduction-cooled current leads are often chosen for their simplicity and reliability. Conduction-cooled leads have the advantage of using common materials, have no superconducting/normal state transition, and have no boil-off vapor to collect. The XFEL (X-Ray Free Electron Laser) magnets are operated at 2 K, which makes vapor-cooled current leads impractical due to the sub-atmospheric bath pressure. This paper presents a numerical model for conduction-cooled current lead heat loads. This model takes into account varying material and fluid thermal properties, varying thicknesses along the length of the lead, heat transfer in the circumferential and longitudinal directions, electrical power dissipation, and the effect of thermal inte...

  19. National solar heating and cooling programs

    Energy Technology Data Exchange (ETDEWEB)

    Blum, S; Allen, J [eds.

    1979-08-01

    This document is a compilation of status reports on the national solar heating and cooling programs of seventeen countries participating in the Committee on the Challenges of Modern Society's Solar Energy Pilot Study. These reports were presented in two special sessions of the 25th Congress of the International Solar Energy Society held in May 1979, in Atlanta, Georgia, USA. This information exchange activity was part of the two-year follow up (1978-1980) of the Solar Energy Pilot Study, which ended in October 1978.

  20. Heat transfer in earth science studies

    Energy Technology Data Exchange (ETDEWEB)

    Carrigan, C. (Lawrence Livermore National Lab., CA (United States)); Chu, T.Y. (Sandia National Labs., Albuquerque, NM (United States))

    1990-01-01

    Earth scientists have long recognized that quantitative models of heat and mass transfer are fundamental to understanding many geophysical phenomena. Transport models have been used to simulate a wide range of earth processes from the crystallization of rock melts to those global mechanisms responsible for driving lithospheric plates and the geodynamo. Since the elegant conductive cooling models of igneous instrusions by Lovering and Jaeger in the 1930's and 1940's, calculations have evolved in their sophistication with the realization of the importance of convective transport and the advent of new methods and supercomputers. Many of the modeling techniques currently used by geoscientists have been adapted from techniques that were originally developed to solve engineering problems. Processes, such as those involving magma transport in volcanic systems, may often be understood by establishing their dynamical similarity with a well-studied engineering application. This book contains a series of papers regarding heat transfer and earth science studies.

  1. Flow structure and heat exchange analysis in internal cooling channel of gas turbine blade

    Science.gov (United States)

    Szwaba, Ryszard; Kaczynski, Piotr; Doerffer, Piotr; Telega, Janusz

    2016-08-01

    This paper presents the study of the flow structure and heat transfer, and also their correlations on the four walls of a radial cooling passage model of a gas turbine blade. The investigations focus on heat transfer and aerodynamic measurements in the channel, which is an accurate representation of the configuration used in aeroengines. Correlations for the heat transfer coefficient and the pressure drop used in the design of radial cooling passages are often developed from simplified models. It is important to note that real engine passages do not have perfect rectangular cross sections, but include corner fillet, ribs with fillet radii and special orientation. Therefore, this work provides detailed fluid flow and heat transfer data for a model of radial cooling geometry which possesses very realistic features.

  2. Advances in heat transfer volume 21

    CERN Document Server

    Hartnett †, James P; Cho, Young I

    1991-01-01

    This volume in a series on heat transfer covers the modelling of the dynamics of turbulent transport processes, supercritical pressures, hydrodynamics, mass transfer near rotating surfaces, lost heat in entropy and the mechanics of heat transfer in a multifluid bubbling pool. Other related titles are "Advances in Heat Transfer", volumes 18, 19 and 20.

  3. Cooling and Heating Solid Quark Stars

    CERN Document Server

    Yu, Meng

    2009-01-01

    We present here a phenomenological solid quark star pulsar model to interpret the observed thermal X-ray emission of isolated pulsars. The heat capacity for solid quark stars was found to be quite small, so that the residual internal stellar heat gained at the birth of the star could be dissipated in an extremely short timescale. However, the bombardment induced by backflowing plasma at the poles of solid quark stars would get the stars be reheated, so that long term soft X-ray emission can be sustained. Such a scenario could be used for those X-ray pulsars with significant magnetospheric activities, and their cooling processes would thus be established. Dim X-ray isolated neutron stars (XDINs) as well as compact central objects (CCOs) have been observed with dominant soft X-ray radiation combined with little magnetospheric manifestations. Such sources could be solid quark stars accreting in the propeller regime.

  4. Engineering heat transfer

    CERN Document Server

    Annaratone, Donatello

    2010-01-01

    This book is a generalist textbook; it is designed for anybody interested in heat transmission, including scholars, designers and students. Two criteria constitute the foundation of Annaratone's books, including the present one. The first one consists of indispensable scientific rigor without theoretical exasperation. The inclusion in the book of some theoretical studies, even if admirable for their scientific rigor, would have strengthened the scientific foundation of this publication, yet without providing the reader with further applicable know-how. The second criterion is to deliver practi

  5. Essentials of radiation heat transfer

    CERN Document Server

    Balaji

    2014-01-01

    Essentials of Radiation Heat Transfer is a textbook presenting the essential, fundamental information required to gain an understanding of radiation heat transfer and equips the reader with enough knowledge to be able to tackle more challenging problems. All concepts are reinforced by carefully chosen and fully worked examples, and exercise problems are provided at the end of every chapter. In a significant departure from other books on this subject, this book completely dispenses with the network method to solve problems of radiation heat transfer in surfaces. It instead presents the powerful radiosity-irradiation method and shows how this technique can be used to solve problems of radiation in enclosures made of one to any number of surfaces. The network method is not easily scalable. Secondly, the book introduces atmospheric radiation, which is now being considered as a potentially important area, in which engineers can contribute to the technology of remote sensing and atmospheric sciences in general, b...

  6. Low Temperature Heating and High Temperature Cooling in Buildings

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk

    , a single-family house designed for plus-energy targets and equipped with a radiant water-based floor heating and cooling system was studied by means of full-scale measurements, dynamic building simulations and thermodynamic evaluation tools. Thermal indoor environment and energy performance of the house...... performance of heating and cooling systems for achieving the same thermal indoor environment. The results show that it is crucial to minimize the heating and cooling demands in the design phase since these demands determine the terminal units and heat sources and sinks that could be used. Low temperature...... heating and high temperature cooling systems (a radiant water-based floor heating and cooling system in this study) proved to be superior to compared systems, evaluated with different system analysis tools; energy, exergy, and entransy. Radiant systems should be coupled to appropriate heating and cooling...

  7. Assessment of the Use of Nitrogen Trifluoride for Purifying Coolant and Heat Transfer Salts in the Fluoride Salt-Cooled High-Temperature Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Scheele, Randall D.; Casella, Andrew M.

    2010-09-28

    This report provides an assessment of the use of nitrogen trifluoride for removing oxide and water-caused contaminants in the fluoride salts that will be used as coolants in a molten salt cooled reactor.

  8. Analysis and experimental study of heat transfer in cryogenic pneumatic mist jet cooling%液滴低温气体雾化射流冷却换热理论分析与实验研究

    Institute of Scientific and Technical Information of China (English)

    管小燕; 任家隆

    2009-01-01

    Discusses the principle and characteristic of cryogenic pneumatic mist jet cooling.Based on the pool film boiling,the jet is regard as the disturbance on it.It founds a model of fogdrop jet in pouring cutting area to cool high temperature wall,and discusses the heat tramfer coefficient.The effect of water density on spray cooling heat transfer coefficient is emphatically analyzed.The experiment on cooling effect in cryogenic pneumatic mist jet cooling Ti-6Al14V auoy surface is put up with different water density and the bestest water density in test sample with the temperature of 100℃,150℃,200℃ and 250℃ is got.Theoretical basis of water density to cutting effect is discussed.the result proved was instructive in actual application.%论述低温气体雾化射流冷却原理及特点,以池内膜态沸腾为基础,将喷雾颗粒的冲击作为一种扰动,建立雾滴射流进入切削区冷却高温壁面的模型,讨论雾滴冷却高温壁面的换热系数,着重探讨工艺参数水流密度对喷雾冷却换热系数的影响.进行了不同水剂量的低温气体雾化射流冷却钛合金高温壁面的瞬态实验,获得了钛合金试件表面温度分别为100℃、150℃、200℃和250℃时,低温气体雾化射流冷却达到最佳冷却效果时水剂量,分析了水剂量对冷却效果的理论依据,结果证实该模型对实际应用具有一定的指导作用.

  9. 基于泛函变分和变热物性的层冷传热建模%Heat Transfer Modeling in Laminar Cooling Based on Functional Variation and Variable Thermo-physical Parameters

    Institute of Scientific and Technical Information of China (English)

    陈水宣; 邹俊; 谢丹

    2012-01-01

    The heat transfer of steels in laminar cooling process of hot strip mill was analyzed and partial differential models were proposed with boundary conditions of thermal radiation and cooling water convective equations.Based on the functional variation principle,the models were solved and node temperature on discrete time was obtained.To further enhance the temperature model calculation precision,thermal material properties including density,specific heat capacity and thermal conductivity were experimentally measured in Baosteel Gleeble thermal simulation equipment for three different carbon steels and the method of least squares was used to statistically derive regression models for the properties.Furthermore,the heat transfer coefficients of water and air cooling were reversely calculated and optimized based on actual measured temperature to meet the long-term stability of the application of the models.The numerical simulation and experimental results show that the setup accuracy of temperature prediction system of ROT was effectively improved.%分析板材在层冷过程中的传热,建立以热辐射和冷却水对流换热方程为边界条件的偏微分热传导模型,并基于泛函变分原理进行离散求解,获得各离散时间节点上的温度。为进一步提高该温度模型计算精度,在宝钢Gleeble热模拟实验机上测定3种碳钢样本的密度、比热容和热导率等热物性参数随温度变化的函数关系,采用最小二乘法建立回归模型,线性插值后用于温度场定量计算。此外,采用层冷实测温度反算和优化水冷、空冷换热系数,以满足模型现场长期应用的稳定性要求。结果表明,改造后层冷温度设定系统的精度能较准确地反映板材在层冷过程的温度变化,温度模型计算值与实测值吻合良好。

  10. A fundamentally new approach to air-cooled heat exchangers.

    Energy Technology Data Exchange (ETDEWEB)

    Koplow, Jeffrey P.

    2010-01-01

    boundary layer region, diffusive transport is the dominant mechanism for heat transfer. The resulting thermal bottleneck largely determines the thermal resistance of the heat exchanger. No one has yet devised a practical solution to the boundary layer problem. Another longstanding problem is inevitable fouling of the heat exchanger surface over time by particulate matter and other airborne contaminants. This problem is especially important in residential air conditioner systems where often little or no preventative maintenance is practiced. The heat sink fouling problem also remains unsolved. The third major problem (alluded to earlier) concerns inadequate airflow to heat exchanger resulting from restrictions on fan noise. The air-cooled heat exchanger described here solves all of the above three problems simultaneously. The 'Air Bearing Heat Exchanger' provides a several-fold reduction in boundary layer thickness, intrinsic immunity to heat sink fouling, and drastic reductions in noise. It is also very practical from the standpoint of cost, complexity, ruggedness, etc. Successful development of this technology is also expected to have far reaching impact in the IT sector from the standpointpoint of solving the 'Thermal Brick Wall' problem (which currently limits CPU clocks speeds to {approx}3 GHz), and increasing concern about the the electrical power consumption of our nation's information technology infrastructure.

  11. Oesophageal heat transfer properties indication of segmental blood flow changes during distension

    DEFF Research Database (Denmark)

    Liao, Donghua; Frøkjær, Jens Brøndum; Brock, Christina

    2008-01-01

    on measurement of heat transfer. A bag was distended in the distal oesophagus of six healthy subjects followed by cooling or heating of the bag fluid to 5 or 60 degrees C. After equilibrium, the temperature was allowed to change back to body temperature. The temperature was recorded together with intraluminal...... ultrasound imaging, allowing assessment of the heat transfer properties at different bag volumes. The heat transfer constants were higher after heating the bag than after cooling the bag (Tukey, P heat transfer constants after heating the bag decreased as function of bag volumes whereas the heat...... transfer during cooling was not affected by the bag volume (F = 0.9, P = 0.4). The findings indicate that segmental blood flow can be assessed indirectly by calculating the heat transfer properties. Distension induced a drop in regional blood flow. Hence, ischaemia may contribute to distension-induced pain...

  12. Solar heating cooling. Preparation of possible participation in IEA, Solar Heating Cooling Task 25; Solvarmedrevet koeling. Forberedelse af evt. deltagelse i IEA, Solar Heating Cooling Task 25

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    For the Danish solar heating industries it is interesting to discuss the domestic market possibilities and the export possibilities for solar heating cooling systems. The Danish solar heating sector also wants to participate in the international collaboration within IEA Solar Heating and Cooling Task 25 'Solar Assisted Air Conditioning of Buildings'. The Danish Energy Agency therefore has granted means for this project to discuss: The price of cooling for 3 different solar cooling methods (absorption cooling, desiccant cooling and ejector cooling); Market possibilities in Denmark and abroad; The advantages by Danish participation in IEA Task 25. The task has been solved through literature studies to establish status for the 3 technologies. It turned out that ejector cooling by low temperatures (85 deg. C from the solar collector) exists as pilot plants in relation to district heating, but is still not commercial accessible. Desiccant cooling, where the supplied heat has temperatures down to 55 deg. C is a well-developed technology. However only a handful of pilot plants with solar heating exists, and thus optimization relating to operation strategy and economy is on the experimental stage. Absorption cooling plants driven by solar heating are found in a large number in Japan and are also demonstrated in several other countries. The combination of absorption heating pump and solar heating is considered to be commercial accessible. Solar heating is interesting as heat source of to the exent that it can replace other sources of heat without the economy being depreciated. This can be the case in South Europe if: 1) oil or natural gas is used for heating; 2) a solar heating system already exists, e.g. for domestic water supply, and is installed so that the marginal costs by solar heating supply of the ventilation plant is reduced. All in all the above conditions mean that the market for solar heating for cooling is very limited in Europe, where almost

  13. FILM-30: A Heat Transfer Properties Code for Water Coolant

    Energy Technology Data Exchange (ETDEWEB)

    MARSHALL, THERON D.

    2001-02-01

    A FORTRAN computer code has been written to calculate the heat transfer properties at the wetted perimeter of a coolant channel when provided the bulk water conditions. This computer code is titled FILM-30 and the code calculates its heat transfer properties by using the following correlations: (1) Sieder-Tate: forced convection, (2) Bergles-Rohsenow: onset to nucleate boiling, (3) Bergles-Rohsenow: partially developed nucleate boiling, (4) Araki: fully developed nucleate boiling, (5) Tong-75: critical heat flux (CHF), and (6) Marshall-98: transition boiling. FILM-30 produces output files that provide the heat flux and heat transfer coefficient at the wetted perimeter as a function of temperature. To validate FILM-30, the calculated heat transfer properties were used in finite element analyses to predict internal temperatures for a water-cooled copper mockup under one-sided heating from a rastered electron beam. These predicted temperatures were compared with the measured temperatures from the author's 1994 and 1998 heat transfer experiments. There was excellent agreement between the predicted and experimentally measured temperatures, which confirmed the accuracy of FILM-30 within the experimental range of the tests. FILM-30 can accurately predict the CHF and transition boiling regimes, which is an important advantage over current heat transfer codes. Consequently, FILM-30 is ideal for predicting heat transfer properties for applications that feature high heat fluxes produced by one-sided heating.

  14. Experimental investigation on Heat Transfer Performance of Annular Flow Path Heat Pipe

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Guk; Kim, Kyung Mo; Jeong, Yeong Shin; Bang, In Cheol [UNIST, Ulsan (Korea, Republic of)

    2015-05-15

    Mochizuki et al. was suggested the passive cooling system to spent nuclear fuel pool. Detail analysis of various heat pipe design cases was studied to determine the heat pipes cooling performance. Wang et al. suggested the concept PRHRS of MSR using sodium heat pipes, and the transient performance of high temperature sodium heat pipe was numerically simulated in the case of MSR accident. The meltdown at the Fukushima Daiichi nuclear power plants alarmed to the dangers of station blackout (SBO) accident. After the SBO accident, passive decay heat removal systems have been investigated to prevent the severe accidents. Mochizuki et al. suggested the heat pipes cooling system using loop heat pipes for decay heat removal cooling and analysis of heat pipe thermal resistance for boiling water reactor (BWR). The decay heat removal systems for pressurized water reactor (PWR) were suggested using natural convection mechanisms and modification of PWR design. Our group suggested the concept of a hybrid heat pipe with control rod as Passive IN-core Cooling System (PINCs) for decay heat removal for advanced nuclear power plant. Hybrid heat pipe is the combination of the heat pipe and control rod. In the present research, the main objective is to investigate the effect of the inner structure to the heat transfer performance of heat pipe containing neutron absorber material, B{sub 4}C. The main objective is to investigate the effect of the inner structure in heat pipe to the heat transfer performance with annular flow path. ABS pellet was used instead of B{sub 4}C pellet as cylindrical structures. The thermal performances of each heat pipes were measured experimentally. Among them, concentric heat pipe showed the best performance compared with others. 1. Annular evaporation section heat pipe and annular flow path heat pipe showed heat transfer degradation. 2. AHP also had annular vapor space and contact cooling surface per unit volume of vapor was increased. Heat transfer

  15. Experimental research on heat transfer of pulsating heat pipe

    Institute of Scientific and Technical Information of China (English)

    LI Jia; Yan Li

    2008-01-01

    Experimental research was conducted to understand heat transfer characteristic of pulsating heat pipe in this paper,and the PHP is made of high quality glass capillary tube. Under different fill ratio, heat transfer rate and many other influence factors, the flow patterns were observed in the start-up, transition and stable stage. The effects of heating position on heat transfer were discussed. The experimental results indicate that no annular flow appears in top heating condition. Under different fill ratios and heat transfer rate, the flow pattern in PHP is transferred from bulk flow to semi-annular flow and annular flow, and the performance of heat transfer is improved for down heating case. The experimental results indicate that the total heat resistant of PHP is increased with fill ratio, and heat transfer rate achieves optimum at filling rate 50%. But for pulsating heat pipe with changing diameters the thermal resistance is higher than that with uniform diameters.

  16. Thermal transfer structures coupling electronics card(s) to coolant-cooled structure(s)

    Science.gov (United States)

    David, Milnes P; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Parida, Pritish R; Schmidt, Roger R

    2014-12-16

    Cooling apparatuses and coolant-cooled electronic systems are provided which include thermal transfer structures configured to engage with a spring force one or more electronics cards with docking of the electronics card(s) within a respective socket(s) of the electronic system. A thermal transfer structure of the cooling apparatus includes a thermal spreader having a first thermal conduction surface, and a thermally conductive spring assembly coupled to the conduction surface of the thermal spreader and positioned and configured to reside between and physically couple a first surface of an electronics card to the first surface of the thermal spreader with docking of the electronics card within a socket of the electronic system. The thermal transfer structure is, in one embodiment, metallurgically bonded to a coolant-cooled structure and facilitates transfer of heat from the electronics card to coolant flowing through the coolant-cooled structure.

  17. A heat dissipating model for water cooling garments

    Directory of Open Access Journals (Sweden)

    Yang Kai

    2013-01-01

    Full Text Available A water cooling garment is a functional clothing used to dissipate human body’s redundant energy in extravehicular environment or other hot environment. Its heat dissipating property greatly affects body’s heat balance. In this paper, a heat dissipating model for the water cooling garment is established and verified experimentally using the experimental thermal-manikin.

  18. 46 CFR 168.15-45 - Heating and cooling.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Heating and cooling. 168.15-45 Section 168.15-45 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS CIVILIAN NAUTICAL SCHOOL VESSELS Accommodations § 168.15-45 Heating and cooling. All quarters must be adequately heated and...

  19. Solar heating and cooling. Research and development: project summaries

    Energy Technology Data Exchange (ETDEWEB)

    1978-05-01

    The Conservation and Solar Applications Solar Heating and Cooling Research and Development Program is described. The evolution of the R and D program is described and the present program is outlined. A series of project descriptions summarizes the research and development presently supported for further development of collectors, thermal energy storage and heat exchangers, heat pumps, solar cooling, controls, and systems. (MHR)

  20. Hybrid Cooling Loop Technology for Robust High Heat Flux Cooling Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced Cooling Technologies, Inc. proposes to develop a hybrid cooling loop technology for space thermal control. The proposed technology combines the high heat...

  1. Simulation of temperature in office with building integrated heating and cooling system

    DEFF Research Database (Denmark)

    Weitzmann, Peter

    2002-01-01

    by raising the temperature of the concrete to slightly above the desired room temperature. Another way of solving the problem of cooling is by using building integrated cooling in floors. This technique utilizes the thermal mass of concrete in the floors, by integrating PEX pipes in the floor. By maintaining...... and thermal comfort parameters. The model is based on a numerical Finite Control Volume (FCV) method for the heat transfer in walls, ceiling, windows and floor. The model uses both convective and radiative heat transfer to the room air and between the room surfaces. The simulation model can be used...... for calculating situations with both cooling and heating demands. Using the model it is therefore possible to assess the thermal environment, and furthermore to calculate the energy consumption required for both heating and cooling. In the paper different construction types of the floor are examined, as well...

  2. Mini-channel evaporator/heat pipe assembly for a chip cooling vapor compression refrigeration system

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Guilherme B.; Barbosa, Jader R. Jr.; Prata, Alvaro T. [Polo - Research Laboratories for Emerging Technologies in Cooling and Thermophysics, Department of Mechanical Engineering, Campus Universitario, Trindade, Federal University of Santa Catarina, Florianopolis, SC 88040900 (Brazil)

    2010-11-15

    We investigate a novel evaporator design for a small-scale refrigeration system whose function is to assist the existing heat pipe technology currently used in chip cooling of portable computers. A heat transfer model for the evaporator/heat pipe assembly was devised specifically for sizing the evaporator in order to keep the chip surface temperature below a certain value. A prototype was tested with R-600a at saturation temperatures of 45 and 55 C, mass flow rates between 0.5 and 1.5 kg h{sup -1} and heat transfer rates between 30 and 60 W. The experimental results demonstrated that the average refrigerant-side heat transfer coefficient is more sensitive to a change in the refrigerant mass flux than to changes in the saturation temperature and heat transfer rate. The agreement between the calculated heat transfer coefficient and the data was within {+-}10% for the conditions evaluated. (author)

  3. Thermo Active Building Systems – Using Building Mass To Heat and Cool

    DEFF Research Database (Denmark)

    Olesen, Bjarne W.

    2014-01-01

    Using the thermal storage capacity of the concrete slabs between each floor in multistory buildings to heat or cool is a trend that began in the early 1990s in Switzerland.1,2 Pipes carrying water for heating and cooling are embedded in the center of the concrete slab. In central Europe (Germany......, Austria, Netherlands, etc.), this type of system has been installed in a significant number of new office buildings since the late 1990s. The trend is spreading to other parts of the world (the rest of Europe, North America and Asia). Thermo active building systems (TABS) are primarily used for cooling...... multistory buildings. By activating the building mass, there is a direct heating-cooling effect. Also, because of the thermal mass, the peak load will be reduced and some of the cooling load will be transferred beyond the time of occupancy. Because these systems for cooling operate at water temperatures...

  4. Temperature and thermal stress evolutions in sapphire crystal during the cooling process by heat exchanger method

    Science.gov (United States)

    Ma, Wencheng; Zhao, Wenhan; Wu, Ming; Ding, Guoqiang; Liu, Lijun

    2017-09-01

    Transient numerical calculations were carried out to predict the evolutions of temperature and thermal stress in sapphire single crystal during the cooling process by heat exchanger method (HEM). Internal radiation in the semitransparent sapphire crystal was taken into account using the finite volume method (FVM) in the global heat transfer model. The numerical results seem to indicate that the narrow bottom region of the sapphire crystal is subjected to high thermal stress during the cooling process, which could be responsible for the seed cracking of the as-grown crystal, while the thermal stress is relatively small in the central main body of the crystal, and is less than 10 MPa during the whole cooling process. The fast decrease of the thermal stress in the bottom region of the crystal during the initial stage of cooling process is dominated by the reduction of the cooling helium gas in the heat exchanger shaft, and is not significantly affected by the heating power reduction rate.

  5. Heat transfer to finned tubes exposed to hot waste gas

    Energy Technology Data Exchange (ETDEWEB)

    Scholand, E.; Kremer, H.

    1975-05-01

    Transfer of heat by forced convection to finned tubes, particularly to those with an elliptical center pipe, is described. These pipes are used in gas-fired water heaters, boilers, and heat exchangers. Finned tubes in a test tunnel were exposed to a stream of waste gas from a gas/air mixture at different Reynolds numbers. Mathematical relationships showing the dependence of the Nusselt number on the Reynolds number and on the geometry of the tubes were derived. The single pipe showed a significant drop in the heat-transfer coefficient as the gap between fins became closer. The results of the measurement of heat transfer by forced convection to finned tubes were expressed in a standard form for all tubes. The same heat transfer law can be applied to electrically heated finned tubes exposed to a stream of cooling air.

  6. Army Gas-Cooled Reactor Systems Program. ML-1 analytical design report. Volume II. Systems analysis: heat transfer and fluid flow

    Energy Technology Data Exchange (ETDEWEB)

    None

    1961-01-01

    The analysis preceding and supporting the design of the cooling system of the ML-1, a mobile, low-power, nuclear power plant, is described in sufficient detail for an engineer to follow the development of the design. Test results and similar data are used to support the calculations whenever possible.

  7. Process heat transfer principles, applications and rules of thumb

    CERN Document Server

    Serth, Robert W

    2014-01-01

    Process Heat Transfer is a reference on the design and implementation of industrial heat exchangers. It provides the background needed to understand and master the commercial software packages used by professional engineers in the design and analysis of heat exchangers. This book focuses on types of heat exchangers most widely used by industry: shell-and-tube exchangers (including condensers, reboilers and vaporizers), air-cooled heat exchangers and double-pipe (hairpin) exchangers. It provides a substantial introduction to the design of heat exchanger networks using pinch technology, the mos

  8. Utilization of the horizontal ground heat exchanger in the heating and cooling system of a residential building

    Directory of Open Access Journals (Sweden)

    Hanuszkiewicz-Drapała Małgorzata

    2016-03-01

    Full Text Available This paper presents the results of thermodynamic analyses of a system using a horizontal ground heat exchanger to cool a residential building in summer and heat it in the autumn-winter period. The main heating device is a vapour compression heat pump with the ground as the lower heat source. The aim of the analyses is to examine the impact of heat supply to the ground in the summer period, when the building is cooled, on the operation of the heating system equipped with a heat pump in the next heating season, including electricity consumption. The processes occurring in cooling and heating systems have an unsteady nature. The main results of the calculations are among others the time-dependent values of heat fluxes extracted from or transferred to the ground heat exchanger, the fluxes of heat generated by the heat pump and supplied to the heated building by an additional heat source, the parameters in characteristic points of the systems, the temperature distributions in the ground and the driving electricity consumption in the period under analysis. The paper presents results of analysis of cumulative primary energy consumption of the analyzed systems and cumulative emissions of harmful substances.

  9. Utilization of the horizontal ground heat exchanger in the heating and cooling system of a residential building

    Science.gov (United States)

    Hanuszkiewicz-Drapała, Małgorzata; Bury, Tomasz

    2016-03-01

    This paper presents the results of thermodynamic analyses of a system using a horizontal ground heat exchanger to cool a residential building in summer and heat it in the autumn-winter period. The main heating device is a vapour compression heat pump with the ground as the lower heat source. The aim of the analyses is to examine the impact of heat supply to the ground in the summer period, when the building is cooled, on the operation of the heating system equipped with a heat pump in the next heating season, including electricity consumption. The processes occurring in cooling and heating systems have an unsteady nature. The main results of the calculations are among others the time-dependent values of heat fluxes extracted from or transferred to the ground heat exchanger, the fluxes of heat generated by the heat pump and supplied to the heated building by an additional heat source, the parameters in characteristic points of the systems, the temperature distributions in the ground and the driving electricity consumption in the period under analysis. The paper presents results of analysis of cumulative primary energy consumption of the analyzed systems and cumulative emissions of harmful substances.

  10. Application of Heat Pump in Cooling Water System of HIRFL

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Accelerator generates a lot of heat when it is working.It must be cooled by the circulating cooling water.Generally the heat was released to atimosphere by the cooling water tower.Because the heat energy is very huge(about 2M watts for HIRFL),it is big waste and the machine can’t be cooled to appropriate temperature when ambient temperature is high in summer.In order to solve the problems,the heat pump has been used

  11. Public policy for solar heating and cooling

    Science.gov (United States)

    Hirshberg, A. S.

    1976-01-01

    Recent analyses indicated that solar heating and cooling systems for residential buildings are nearly economically competitive with conventional fossil fuel or electric systems, the former having higher initial cost but a lower operating cost than the latter. The paper examines obstacles to the widespread acceptance and use of solar space conditioning systems and explores some general policies which could help to overcome them. The discussion covers such institutional barriers limiting the adoption of solar technologies as existing building codes, financing constraints, and organizational structure of the building industry. The potential impact of financial incentives is analyzed. It is noted that a tax incentive of 25% could speed the use of solar energy by 7 to 8 years and produce an 8% reduction in fossil fuel use by 1990. A preliminary incentive package which could be helpful in promoting solar energy both at federal and state levels is proposed, and the necessary incentive level is analysed.

  12. Public policy for solar heating and cooling

    Science.gov (United States)

    Hirshberg, A. S.

    1976-01-01

    Recent analyses indicated that solar heating and cooling systems for residential buildings are nearly economically competitive with conventional fossil fuel or electric systems, the former having higher initial cost but a lower operating cost than the latter. The paper examines obstacles to the widespread acceptance and use of solar space conditioning systems and explores some general policies which could help to overcome them. The discussion covers such institutional barriers limiting the adoption of solar technologies as existing building codes, financing constraints, and organizational structure of the building industry. The potential impact of financial incentives is analyzed. It is noted that a tax incentive of 25% could speed the use of solar energy by 7 to 8 years and produce an 8% reduction in fossil fuel use by 1990. A preliminary incentive package which could be helpful in promoting solar energy both at federal and state levels is proposed, and the necessary incentive level is analysed.

  13. Ground Source Geothermal District Heating and Cooling System

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, James William [Ball State Univ., Muncie, IN (United States)

    2016-10-21

    Ball State University converted its campus from a coal-fired steam boiler district heating system to a ground source heat pump geothermal district system that produces simultaneously hot water for heating and chilled water for cooling. This system will include the installation of 3,600 four hundred feet deep vertical closed loop boreholes making it the largest ground source geothermal district system in the country. The boreholes will act as heat exchangers and transfer heat by virtue of the earth’s ability to maintain an average temperature of 55 degree Fahrenheit. With growing international concern for global warming and the need to reduce worldwide carbon dioxide loading of the atmosphere geothermal is poised to provide the means to help reduce carbon dioxide emissions. The shift from burning coal to utilizing ground source geothermal will increase electrical consumption but an overall decrease in energy use and reduction in carbon dioxide output will be achieved. This achievement is a result of coupling the ground source geothermal boreholes with large heat pump chiller technology. The system provides the thermodynamic means to move large amounts of energy with limited energy input. Ball State University: http://cms.bsu.edu/About/Geothermal.aspx

  14. Some observations on the historical development of conduction heat transfer

    Science.gov (United States)

    Cheng, Kwo Chang

    An attempt is made to obtain historical perspectives on the development of the mathematical theory of heat conduction considering Newton's law of cooling (1701) and its close connection with Fourier's work from 1807 to 1822 resulting in his epoch-making treatise on "The Analytical Theory of Heat". Fourier was the principal architect of the heat conduction theory. Fourier's work established a new methodology for the formulation and solution of physical problems, based on partial differential equations and marked a major turning point in the history of physics. The developments in the periods 1822 to 1900 and 1900 to 1950 are also briefly reviewed as are the classical (analytical) and numerical methods of solution for heat conduction problems. The analogy in heat, momentum, and mass transfer for transport phenomena is discussed. A list of recent conduction heat transfer books is presented to show the scope of recent developments. Some observations on conduction heat transfer are noted.

  15. Optimal Cooling Load and COP Relationship of a Four-Heat-Reservoir Endoreversible Absorption Refrigeration Cycle

    Directory of Open Access Journals (Sweden)

    Chih Wu

    2004-06-01

    Full Text Available Abstract: On the basis of a four-heat-reservoir endoreversible absorption refrigeration cycle model, another linear heat transfer law [i.e., the heat-flux] is adopted, the fundamental optimal relation between the coefficient of performance (COP and the cooling load, as well as the maximum cooling load and the corresponding COP of the cycle coupled to constant-temperature heat reservoirs are derived by using finite-time thermodynamics or thermodynamic optimization. The optimal distribution of the heat-transfer surface areas is also obtained. Moreover, the effects of the cycle parameters on the COP and the cooling load of the cycle are studied by detailed numerical examples. The results obtained herein are of importance to the optimal design and performance improvement of an absorption refrigeration cycle.

  16. Analysis of the adsorption process and of desiccant cooling systems: a pseudo- steady-state model for coupled heat and mass transfer. [DESSIM, DESSIM2, DESSIM4

    Energy Technology Data Exchange (ETDEWEB)

    Barlow, R.S.

    1982-12-01

    A computer model to simulate the adiabatic adsorption/desorption process is documented. Developed to predict the performance of desiccant cooling systems, the model has been validated through comparison with experimental data for single-blow adsorption and desorption. A literature review on adsorption analysis, detailed discussions of the adsorption process, and an initial assessment of the potential for performance improvement through advanced component development are included.

  17. Heat Transfer Enhancement by Finned Heat Sinks with Micro-structured Roughness

    Science.gov (United States)

    Ventola, L.; Chiavazzo, E.; Calignano, F.; Manfredi, D.; Asinari, P.

    2014-04-01

    We investigated the benefits of micro-structured roughness on heat transfer performance of heat sinks, cooled by forced air. Heat sinks in aluminum alloy by direct metal laser sintering (DMLS) manufacturing technique were fabricated; values of the average surface roughness Ra from 1 to 25 microns (standard milling leads to roughness around 1 micron) under turbulent regimes (Reynolds number based on heating edge from 3000 to 17000) have been explored. An enhancement of 50% in thermal performances with regards to standard manufacturing was observed. This may open the way for huge boost in the technology of electronic cooling by DMLS.

  18. Heat Transfer in a Superelliptic Transition Duct

    Science.gov (United States)

    Poinsatte, Philip; Thurman, Douglas; Hippensteele, Steven

    2008-01-01

    Local heat transfer measurements were experimentally mapped using a transient liquid-crystal heat transfer technique on the surface of a circular-to-rectangular transition duct. The transition duct had a length-to-diameter ratio of 1.5 and an exit-plane aspect ratio of 3. The crosssectional geometry was defined by the equation of a superellipse. The cross-sectional area was the same at the inlet and exit but varied up to 15 percent higher through the transition. The duct was preheated to a uniform temperature (nominally 64 C) before allowing room temperature air to be suddenly drawn through it. As the surface cooled, the resulting isothermal contours on the duct surface were revealed using a surface coating of thermochromic liquid crystals that display distinctive colors at particular temperatures. A video record was made of the surface temperature and time data for all points on the duct surfaces during each test. Using this surface temperature-time data together with the temperature of the air flowing through the model and the initial temperature of the model wall, the heat transfer coefficient was calculated by employing the classic one-dimensional, semi-infinite wall heat transfer conduction model. Test results are reported for inlet diameter-based Reynolds numbers ranging from 0.4x106 to 2.4x106 and two grid-generated freestream turbulence intensities of about 1 percent, which is typical of wind tunnels, and up to 16 percent, which may be more typical of real engine conditions.

  19. Trap For Noncondensable Gas In Heat-Transfer Fluid

    Science.gov (United States)

    Edelstein, Fred; Cordes, Bruce; Brown, Richard F.

    1990-01-01

    Trap acts as scrubber by removing noncondensable gas as it is generated slowly or released by outgassing in vapor/liquid heat-transfer system. Includes tube of stainless steel or other poorly thermally conductive material attached to tap on top of main vapor line where vapor flows toward condenser. Sub-cooled liquid from outlet of condenser cools upper end of tube below vapor temperature.

  20. Heat-transfer tests of aqueous ethylene glycol solutions in an electrically heated tube

    Science.gov (United States)

    Bernardo, Everett; Eian, Carroll S

    1945-01-01

    As part of an investigation of the cooling characteristics of liquid-cooled engines, tests were conducted with an electrically heated single-tube heat exchanger to determine the heat-transfer characteristics of an-e-2 ethylene glycol and other ethylene glycol-water mixtures. Similar tests were conducted with water and commercial butanol (n-butyl alcohol) for check purposes. The results of tests conducted at an approximately constant liquid-flow rate of 0.67 pound per second (Reynolds number, 14,500 to 112,500) indicate that at an average liquid temperature 200 degrees f, the heat-transfer coefficients obtained using water, nominal (by volume) 30 percent-70 percent and 70 percent-30 percent glycol-water mixtures are approximately 3.8, 2.8, and 1.4 times higher, respectively, than the heat-transfer coefficients obtained using an-e-2 ethylene glycol.

  1. Transient Heat Transfer in Cylinpers.

    Directory of Open Access Journals (Sweden)

    M.G. Chopra

    2000-07-01

    Full Text Available A numerical solution has been obtained for transient heat transfer in cylinders by appropriate choice of body ,conforming grid points. The physical domain is transformed to computational domain using elliptic partial differential equation technique, wherein the grid spacing becomes uniform. The advantage of this method is that the discretisation of transformed equations. and accompanying boundary conditipns becdme very simple. The applicability of this method is very broad, as it can beused for carryinI giout study of any comple'x domain in contrast to finite difference methods, which have limited applicability. Detailedcalculations have been carried out to trace the evolution of temperaturedistribution frpm the initiial stages to the steadystate for circular cylinder, elliptical cylinder and square block with circular hole. This paper is aimed for general-shaped bodies and it has been applied to studytransient heat transfer in combustion-driven shock tube.

  2. Analysis of reverse heat transfer for conventional and optimized lubri-cooling methods during tangential surface grinding of ABNT 1020 steel

    Directory of Open Access Journals (Sweden)

    Henrique Cotait Razuk

    Full Text Available Abstract A numerical thermal model was developed to evaluate the heat flux which is conducted to a rectangular workpiece of steel plate ABNT 1020, thus making it possible to compute the maximum temperature in the grinding surface, taking into account the rectangular distribution of heat flux, the thermal properties of the grinding wheel conventional Al2O3, the piece to be machined and the lubri-refrigerating fluid. The finite volume method was employed for the discretization of the direct thermal problem from the heat diffusion equation associated with the two-dimensional problem of heat conduction in transient regime. The inverse thermal problem was solved by the Golden Section technique. The thermal flux, when compared to the conventional technique of method of application fluid, was reduced by 84.0% in the practices performed with cutting depth of 30µm, at 74.0% in practices with cutting depth of 45µm and 61.2% in the aggressive practices of 60µm, thus demonstrating the applicability of the optimized method for fluid application.

  3. Heat transfer enhancement by pin elements

    Energy Technology Data Exchange (ETDEWEB)

    Sahiti, N.; Durst, F.; Dewan, A. [LSTM-Erlangen, Institute of Fluid Mechanics, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Cauerstrasse 4, D-91058 Erlangen (Germany)

    2005-11-01

    Heat transfer enhancement is an active and important field of engineering research since increases in the effectiveness of heat exchangers through suitable heat transfer augmentation techniques can result in considerable technical advantages and savings of costs. Considerable enhancements were demonstrated in the present work by using small cylindrical pins on surfaces of heat exchangers. A partly quantitative theoretical treatment of the proposed method is presented. It uses simple relationships for the conductive and convective heat transfer to derive an equation that shows which parameters permit the achievement of heat transfer enhancements. Experiments are reported that demonstrate the effectiveness of the results of the proposed approach. It is shown that the suggested method of heat transfer enhancements is much more effective than existing methods, since it results in an increase in heat transfer area (like fins) and also an increase in the heat transfer coefficient. (author)

  4. Boiling Heat Transfer to Halogenated Hydrocarbon Refrigerants

    Science.gov (United States)

    Yoshida, Suguru; Fujita, Yasunobu

    The current state of knowledge on heat transfer to boiling refrigerants (halogenated hydrocarbons) in a pool and flowing inside a horizontal tube is reviewed with an emphasis on information relevant to the design of refrigerant evaporators, and some recommendations are made for future research. The review covers two-phase flow pattern, heat transfer characteristics, correlation of heat transfer coefficient, influence of oil, heat transfer augmentation, boiling from tube-bundle, influence of return bend, burnout heat flux, film boiling, dryout and post-dryout heat transfer.

  5. Studies of Phase Change Materials and a Latent Heat Storage Unit Used for a Natural Circulation Cooling/Latent Heat Storage System

    Science.gov (United States)

    Sakitani, Katsumi; Honda, Hiroshi

    Experimental and theoretical studies were made of the heat transfer characteristics of a latent heat storage unit used for a natural circulation cooling /latent heat storage system. Heating and cooling curves of the latent heat storage unit undergoing solid-liquid phase change of a PCM (lauric acid) was obtained by using anatural circulation loop of R22 which consisted of an electrically heated evaporater, a water cooled condenser and the latent heat storage unit. The latent heat storage unit showed a heat transfer performance which was high enough for practical use. An approximate theoretical analysis was conducted to investigate transient behavior of the latent heat storage unit. Predictions of the refrigerant and outer surface temperatures during the melting process were in fair agreement with the experimental data, whereas that of the refrigerant temperature during the solidification process was considerably lower than the measurement.

  6. Heat Driven Cooling in District Energy Systems; Vaermedriven Kyla

    Energy Technology Data Exchange (ETDEWEB)

    Rydstrand, Magnus; Martin, Viktoria; Westermark, Mats [Royal Inst. of Technology, Stockholm (Sweden). Dept. of Chemical Engineering and Technology

    2004-07-01

    This report is reviewing different heat driven technologies for the production of cooling. It is shown that the supply of cooling gives the highest fuel utilization if heat from CHP production is used for the production of cooling instead of maximizing the electricity output in a condensing plant. High fuel utilization is reached since the direct production of cooling from heat is a thermodynamic shortcut as compared to the production of electricity as an intermediate product before cooling is produced. At direct production of cooling from heat it is possible to obtain 70 percent of the obtainable cooling of an ideal process. If electricity is produced from heat, 70 percent electricity could be obtained as compared to an ideal process. If this electricity would be used for the production of cooling 70 percent of the obtainable cooling in an ideal process would the result. The total production of cooling from heat with electricity as an intermediate product would therefore give 50 percent cooling as compared to an ideal process. Hence, heat driven cooling will give more cooling for a given fuel input. In the review of the different heat driven cooling options it was found that there are many alternatives suitable for different applications. Absorption cooling is suitable for water distributed cooling if the latent cooling load is low. Desiccant cooling is believed to have a large market in climates (applications) with high latent cooling loads. In the energy efficiency evaluation it is found that the highest fuel utilization is given for a central production of electricity using either district heating or district cooling as the energy carrier to supply cooling. In fact the potential of district heating as the energy carrier is thought to be the largest in large cities with humid climates. Further it is found that the chiller heat sink can contribute significantly to the cost in many applications, especially if water and/or electricity consumption are issues with

  7. Economics of geothermal heating/cooling of Reno Industrial Park

    Energy Technology Data Exchange (ETDEWEB)

    Kanoglu, M.; Cerci, Y.; Cengel, Y.A. [Univ. of Nevada, Reno, NV (United States)] [and others

    1996-12-31

    In this paper the economics of the proposed geothermal district heating/cooling system for the newly developed 1200 acre Industrial Park in Reno is investigated. The district heating/cooling system with 30,000,000 square foot of floor space connected to geothermal appears to be feasible, and financially very attractive. With the drilling of new wells, the geothermal district heating system appears to be capable of meeting the entire space heating requirements of the park as well as the entire cooling needs of potential customers who are expected to use absorption cooling, generating potential revenues of $14,040,000 per year ($8,750,000 from heating and $5,290,000 from cooling). The planned 200-bed Washoe Acute Hospital and the 300-room Marriott hotel in the Industrial park has the potential to generate additional $392,500 per year at a discount of 30 percent.

  8. Simulation on Cooling System of Automotive Waste Heat Thermoelectric Generator

    Directory of Open Access Journals (Sweden)

    Xiaohong Yuan

    2013-06-01

    Full Text Available The cooling system of automobile waste heat Thermoelectric Generator (TEG is researched in the study. Integrated model of cooling system and vehicle is built based on GT-Cool, analysis of the different cooling ways shows that when using independent cooling system, the ratio between power consumption and output is high and system performance is poor; By using integrated cooling system, the expectation of keep constant engine warm up time and synchronous change of water temperature between different tanks is realized after water tanks are improved.

  9. Optimal Control Method of Parabolic Partial Differential Equations and Its Application to Heat Transfer Model in Continuous Cast Secondary Cooling Zone

    Directory of Open Access Journals (Sweden)

    Yuan Wang

    2015-01-01

    Full Text Available Our work is devoted to a class of optimal control problems of parabolic partial differential equations. Because of the partial differential equations constraints, it is rather difficult to solve the optimization problem. The gradient of the cost function can be found by the adjoint problem approach. Based on the adjoint problem approach, the gradient of cost function is proved to be Lipschitz continuous. An improved conjugate method is applied to solve this optimization problem and this algorithm is proved to be convergent. This method is applied to set-point values in continuous cast secondary cooling zone. Based on the real data in a plant, the simulation experiments show that the method can ensure the steel billet quality. From these experiment results, it is concluded that the improved conjugate gradient algorithm is convergent and the method is effective in optimal control problem of partial differential equations.

  10. Evaluation of finite element formulations for transient conduction forced-convection analysis. [of heat transfer for active cooling of hypersonic airframe and engine structures

    Science.gov (United States)

    Thornton, E. A.; Wieting, A. R.

    1979-01-01

    Conventional versus upwind convective finite elements, and lumped versus consistent formulations for practical conduction/forced convection analysis are evaluated on the basis of numerical studies, with finite element and finite difference lumped-parameter temperatures compared to closed-form analytical solutions for convection problems. Attention is given to two practical combined conduction and forced convection applications, stressing that the finite element method, showing superior accuracy, is competitive with the finite difference lumped-parameter method. Also considered are the computational time savings offered by the zero capacitance nodes procedure and comparative finite element and finite difference lumped-parameter computer times. The present study has reference to the design of actively cooled engine and airframe structures for hypersonic flight.

  11. Loop heat pipes - highly efficient heat-transfer devices for systems of sun heat supply

    Energy Technology Data Exchange (ETDEWEB)

    Maydanik, Yu. [Ural Branch of the Russian Academy of Sciences, Ekaterinburg (Russian Federation). Inst. of Thermophysics

    2004-07-01

    Loop heat pipes (LHPs) are hermetic heat-transfer devices operating on a closed evaporation-condensation cycle with the use of capillary pressure for pumping the working fluid [1]. In accordance with this, they possess all the main advantages of conventional heat pipes, but, as distinct from the latter, have a considerably higher heat-transfer capacity, especially when operating in the ''antigravity'' regime, when heat is transferred from above downwards. Besides, LHPs possess a higher functional versatility, are adaptable to different operating conditions and provide great scope for various design embodiments. This is achieved at the expense of both the original design of the device and the properties of the wick - a special capillary structure used for the creation of capillary pressure. The LHP schematic diagram is given in Fig. 1. The device contains an evaporator and a condenser - heat exchanger connected by means of smooth-walled pipe-lines with a relatively small diameter intended for separate motion of vapor and liquid. At present loop heat pipes are most extensively employed in thermoregulation systems of spacecrafts. Miniature LHPs are used for cooling electronics and computers. At the same time there exists a considerable potential of using these devices for the recovery of low-grade (waste) heat from different sources, and also in systems of sun heat supply. In the latter case LHPs may serve as an efficient heat-transfer link between a sun collector and a heat accumulator, which has a low thermal resistance and does not consume any additional energy for pumping the working fluid between them. (orig.)

  12. Heat transfer coefficient for boiling carbon dioxide

    DEFF Research Database (Denmark)

    Knudsen, Hans Jørgen Høgaard; Jensen, Per Henrik

    1998-01-01

    Heat transfer coefficient and pressure drop for boiling carbon dioxide (R744) flowing in a horizontal pipe has been measured. The calculated heat transfer coeeficient has been compared with the Chart correlation of Shah. The Chart Correlation predits too low heat transfer coefficient but the ratio...

  13. Boiling heat transfer in dilute emulsions

    CERN Document Server

    Roesle, Matthew Lind

    2013-01-01

    Boiling Heat Transfer in Dilute Emulsions synthesizes recent advances and established understanding on the subject of boiling in dilute emulsions. Experimental results from various sources are collected and analyzed, including contemporary experiments that correlate visualization with heat transfer data. Published models of boiling heat transfer in dilute emulsions, and their implementation, are described and assessed against experimental data.

  14. Heat exchanger device and method for heat removal or transfer

    Science.gov (United States)

    Koplow, Jeffrey P [San Ramon, CA

    2012-07-24

    Systems and methods for a forced-convection heat exchanger are provided. In one embodiment, heat is transferred to or from a thermal load in thermal contact with a heat conducting structure, across a narrow air gap, to a rotating heat transfer structure immersed in a surrounding medium such as air.

  15. Heat exchanger device and method for heat removal or transfer

    Science.gov (United States)

    Koplow, Jeffrey P

    2013-12-10

    Systems and methods for a forced-convection heat exchanger are provided. In one embodiment, heat is transferred to or from a thermal load in thermal contact with a heat conducting structure, across a narrow air gap, to a rotating heat transfer structure immersed in a surrounding medium such as air.

  16. Economic evaluation of geothermal power generation, heating, and cooling

    Energy Technology Data Exchange (ETDEWEB)

    Kanoglu, Mehmet; Cengel, Yunus A. [Nevada Univ., Dept. of Mechanical Engineering, Reno, NV (United States)

    1999-06-01

    Economic analysis of a typical geothermal resource shows that potential revenues from geothermal heating or cooling can be much larger than those from power generation alone. Geothermal heating may generate up to about 3.1 times and geothermal absorption cooling 2.9 times as much revenue as power generation alone. Similarly, combined power generation and heating may generate about 2.1 times and combined power generation and cooling about 1.2 times as much revenue as power generation alone. Cost and payback period comparison appear to favor power generation, followed by district heating. (Author)

  17. Preliminary design package for prototype solar heating and cooling systems

    Science.gov (United States)

    1978-01-01

    A summary is given of the preliminary analysis and design activity on solar heating and cooling systems. The analysis was made without site specific data other than weather; therefore, the results indicate performance expected under these special conditions. Major items include a market analysis, design approaches, trade studies and other special data required to evaluate the preliminary analysis and design. The program calls for the development and delivery of eight prototype solar heating and cooling systems for installation and operational test. Two heating and six heating and cooling units will be delivered for Single Family Residences, Multiple-family Residences and commercial applications.

  18. An experimental investigation devoted to determine heat transfer characteristics in a radiant ceiling heating system

    Science.gov (United States)

    Koca, Aliihsan; Acikgoz, Ozgen; Çebi, Alican; Çetin, Gürsel; Dalkilic, Ahmet Selim; Wongwises, Somchai

    2017-08-01

    Investigations on heated ceiling method can be considered as a new research area in comparison to the common wall heating-cooling and cooled ceiling methods. In this work, heat transfer characteristics of a heated radiant ceiling system was investigated experimentally. There were different configurations for a single room design in order to determine the convective and radiative heat transfer rates. Almost all details on the arrangement of the test chamber, hydraulic circuit and radiant panels, the measurement equipment and experimental method including uncertainty analysis were revealed in detail indicating specific international standards. Total heat transfer amount from the panels were calculated as the sum of radiation to the unheated surfaces, convection to the air, and conduction heat loss from the backside of the panels. Integral expression of the view factors was calculated by means of the numerical evaluations using Matlab code. By means of this experimental chamber, the radiative, convective and total heat-transfer coefficient values along with the heat flux values provided from the ceiling to the unheated surrounding surfaces have been calculated. Moreover, the details of 28 different experimental case study measurements from the experimental chamber including the convective, radiative and total heat flux, and heat output results are given in a Table for other researchers to validate their theoretical models and empirical correlations.

  19. Optimal configuration for a finite low-temperature source refrigerator cycle with heat transfer law

    Directory of Open Access Journals (Sweden)

    Jun Li, Lingen Chen, Yanlin Ge, Fengrui Sun

    2016-01-01

    Full Text Available The optimal configuration of a refrigeration cycle operating between a finite low-temperature source and an infinite high-temperature sink are derived by using finite time thermodynamics based on a complex heat transfer law, including Newtonian heat transfer law, linear phenomenological heat transfer law, radiative heat transfer law, Dulong-Petit heat transfer law, generalized convective heat transfer law and generalized radiative heat transfer law. In the refrigeration cycle model the only irreversibility of finite rate heat transfer is considered. The optimal relation between cooling load and coefficient of performance (COP of the refrigeration cycle is also derived by using an equivalent temperature of low-temperature source. The obtained results include those with various heat transfer laws and infinite low-temperature source, and can provide some theoretical guidelines for the designs of practical refrigerators.

  20. An assessment of RELAP5 MOD3.1.1 condensation heat transfer modeling with GIRAFFE heat transfer tests

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, B.D.; Parlatan, Y.; Slovik, G.C. [and others

    1995-09-01

    RELAP5 MOD3.1.1 is being used to simulate Loss of Coolant Accidents (LOCA) for the Simplified Boiling Water Reactor (SBWR) being proposed by General Electric (GE). One of the major components associated with the SBWR is the Passive Containment Cooling System (PCCS) which provides the long-term heat sink to reject decay heat. The RELAP5 MOD3.1.1 code is being assessed for its ability to represent accurately the PCCS. Data from the Phase 1, Step 1 Heat Transfer Tests performed at Toshiba`s Gravity-Driven Integral Full-Height Test for Passive Heat Removal (GIRAFFE) facility will be used for assessing the ability of RELAP5 to model condensation in the presence of noncondensables. The RELAP5 MOD3.1.1 condensation model uses the University of California at Berkeley (UCB) correlation developed by Vierow and Schrock. The RELAP5 code uses this heat transfer coefficient with the gas velocity effect multiplier being limited to 2. This heat transfer option was used to analyze the condensation heat transfer in the GIRAFFE PCCS heat exchanger tubes in the Phase 1, Step 1 Heat Transfer Tests which were at a pressure of 3 bar and had a range of nitrogen partial pressure fractions from 0.0 to 0.10. The results of a set of RELAP5 calculations at these conditions were compared with the GIRAFFE data. The effects of PCCS cell noding on the heat transfer process were also studied. The UCB correlation, as implemented in RELAP5, predicted the heat transfer to {plus_minus}5% of the data with a three--node model. The three-node model has a large cell in the entrance region which smeared out the entrance effects on the heat transfer, which tend to overpredict the condensation. Hence, the UCB correlation predicts condensation heat transfer correlation implemented in the code must be removed to allow for accurate calculations with smaller cell sizes.

  1. Heat Transfer in a Thermoacoustic Process

    Science.gov (United States)

    Beke, Tamas

    2012-01-01

    Thermoacoustic instability is defined as the excitation of acoustic modes in chambers with heat sources due to the coupling between acoustic perturbations and unsteady heat addition. The major objective of this paper is to achieve accurate theoretical results in a thermoacoustic heat transfer process. We carry out a detailed heat transfer analysis…

  2. Heat transfer in the Knudsen layer

    Science.gov (United States)

    Sharipov, Felix

    2004-06-01

    A concept of the surface heat conductivity determining a heat transfer in the Knudsen layer was introduced. It has the same order with respect to the Knudsen number as the bulk heat transfer and must be taken into account in practical calculations. Using the Onsager principle the coefficient of the surface heat conductivity was related to the thermal slip coefficient.

  3. Heat Transfer in a Thermoacoustic Process

    Science.gov (United States)

    Beke, Tamas

    2012-01-01

    Thermoacoustic instability is defined as the excitation of acoustic modes in chambers with heat sources due to the coupling between acoustic perturbations and unsteady heat addition. The major objective of this paper is to achieve accurate theoretical results in a thermoacoustic heat transfer process. We carry out a detailed heat transfer analysis…

  4. The role of Compton heating in cluster cooling flows

    CERN Document Server

    Ciotti, L; Pellegrini, S

    2003-01-01

    Recent observations by Chandra and XMM-Newton demonstrate that the central gas in "cooling flow" galaxy clusters has a mass cooling rate that decreases rapidly with decreasing temperature. This contrasts the predictions of a steady state cooling flow model. On the basis of these observational results, the gas can be in a steady state only if a steady temperature dependent heating mechanism is present; alternatively the gas could be in an unsteady state, i.e., heated intermittently. Intermittent heating can be produced by accretion on the supermassive black hole residing in the central cluster galaxy, via Compton heating. This mechanism can be effective provided that the radiation temperature of the emitted spectrum is higher than the gas temperature. Here we explore whether this heating mechanism can be at the origin of the enigmatic behavior of the hot gas in the central regions of ``cooling flow'' clusters. Although several characteristics of Compton heating appear attractive in this respect, we find that t...

  5. Heating and cooling with ground-loop heat pumps; Heizen und Kuehlen mit erdgekoppelten Waermepumpen

    Energy Technology Data Exchange (ETDEWEB)

    Afjei, Th.; Dott, R. [Institut Energie am Bau, Fachhochschule Nordwestschweiz (FHNW), Muttenz (Switzerland); Huber, A. [Huber Energietechnik AG, Zuerich (Switzerland)

    2007-08-15

    This final report for the Swiss Federal Office of Energy (SFOE) presents the results of the SFOE-project 'Heating and cooling with ground coupled heat pumps' in which the benefits and costs of a heat pump heating and cooling system with a borehole heat exchanger were examined. In particular the dimensioning of the hydraulic system, control concept and user behaviour are dealt with. The results of the simulations of thermal building behaviour with MATLAB/SIMULINK, CARNOT, and EWS are discussed. The results of parameter studies carried out, including varying shading, cooling characteristic curves, temperature differences in the heat exchanger and the dead time between heating and cooling mode are discussed. These showed that a simple system with heat pump and borehole heat exchanger for heating or preparation of domestic hot water as well as for passive cooling proved to be the best choice.

  6. Heat transfer capability simulation of high-temperature heat pipe in supersonic vehicle leading edge applications

    Directory of Open Access Journals (Sweden)

    Donghuan Liu

    2016-04-01

    Full Text Available A numerical method is proposed to determine the heat transfer capability of the high-temperature heat pipe and the stagnation temperature with supersonic vehicle leading edge applications. The finite element method is employed here to perform the temperature field simulation. Without considering the heat transfer limitations of the heat pipe, such as capillary limit and sonic limit, both numerical and experimental results indicate that equivalent high thermal conductivity method is a reasonable way to simulate the heat transfer capability of the high-temperature heat pipe in preliminary design of a heat-pipe-cooled leading edge. Several important parameters’ effects on the thermal protection performance are also numerically investigated.

  7. Betaine-based heat transfer fluids as a natural solution for environmental, toxic and corrosion problems in heating and cooling systems; Betaine gebaseerde koudedragers als natuurlijke oplossing voor milieu-, toxiciteit- en corrosieproblemen in verwarming- en koelsystemen

    Energy Technology Data Exchange (ETDEWEB)

    Jokinen, J. [Fortum Oil and Gas Oy, Porvoo (Finland); Willems, B.P.M. [Marketing and Technology Consult, Rijen (Netherlands)

    2005-02-01

    The reason for the study on the title subject was the environmental risk and toxicity of many conventional heat transfer fluids like glycols. Fluid toxicity and environmental risk in building systems and industrial use is becoming less acceptable. Alternative fluids have been sought from among salt solutions and vegetable oils. Still, those alternative materials are not very attractive. Main technical problems have been high viscosity and corrosion. A new possible alternative, a betaine-water solution was tested and developed for heat transfer purposes. Betaine (trimethyl glycine) is a by-product of the sugar industry. Therefore, betaine is completely non-toxic and also not harmful to the environment. Betaine is a renowned substance in the pharmaceutical, cosmetic, food and medical industry. Adequate freezing protection is achieved with betaine concentration of 20-55% by weight. This solution was found to have other good qualities also; it has good heat transfer abilities, is not harmful to materials used in systems and has natural corrosion protection properties. The development work consisted of carefully measuring freeze protection and pipe burst protection with different betaine concentrations, measuring physical properties in the same circumstances and developing the additive package for enhanced corrosion protection. Field-testing was carried out for four years. Testing showed that a betaine-water solution has good thermodynamic properties to be used as a heat transfer fluid in the HVAC industry, with additional environmental-, non-toxic and corrosion properties. The concrete result was a trademark and patent protected new product for the industry. [Dutch] Warmteoverdracht wordt heden ten dage veelvuldig toegepast in zowel de industrie als in kantoren en gebouwen. Hoewel de warmteoverdrachttechnologie enorm is vooruitgegaan worden het potentieel en de voordelen van een zorgvuldig gekozen koudedrager vaak over het hoofd gezien. De selectie van de juiste

  8. Multiple impinging jet arrays. An experimental study on flow and heat transfer

    NARCIS (Netherlands)

    Geers, L.F.G.

    2004-01-01

    Because of their high efficiency and their ability to provide high heat transfer rates, impinging jets are applied for rapid cooling and heating in a wide variety of industrial processes. However, the physical phenomena controlling the heat transfer from impinging jets are to a large degree unknown.

  9. Flow impinging effect of critical heat flux and nucleation boiling heat transfer on a downward facing heating surface

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Huai-En; Chen, Mei-Shiue; Chen, Jyun-Wei; Lin, Wei-Keng; Pei, Bau-Shei [National Tsing Hua Univ., Taiwan (China). Inst. of Nuclear Engineering and Science

    2015-05-15

    Boiling heat transfer has a high heat removal capability in convective cooling. However, the heat removal capability of downward-facing boiling is significantly worse than that of upward-facing cases because of the confined buoyancy effect. This study was inspired by the conception of external reactor vessel cooling (ERVC) condition relevant to the in-vessel retention (IVR) design of Westinghouse AP1000 plant. In the present study, a small-scale test facility had been established to investigate the local phenomena of boiling heat transfer under a downward-facing horizontal heated surface with impinging coolant flow. In this study, the surface temperature, heat flux information and several specific scenes of bubbles are taken down throughout the boiling processes for detailed investigation. It is observed that bubbles are confined under the downward-facing heated surface, which causes a worse heat transfer rate and a lower critical heat flux (CHF) limit than upward-facing boiling. Nevertheless, the impinging coolant flow is found to disturb the thermal boundary layer formed by the heated surface, so the CHF increases with an increase of coolant flow rate. In addition, during nucleate boiling, it is discovered that the growth, combination and dissipation of bubbles induce turbulent wakes and therefore enhance the heat transfer capability.

  10. Enhancement of laminar convective heat transfer using microparticle suspensions

    Science.gov (United States)

    Zhu, Jiu Yang; Tang, Shiyang; Yi, Pyshar; Baum, Thomas; Khoshmanesh, Khashayar; Ghorbani, Kamran

    2016-04-01

    This paper investigates the enhancement of convective heat transfer within a sub-millimetre diameter copper tube using Al2O3, Co3O4 and CuO microparticle suspensions. Experiments are conducted at different particle concentrations of 1.0, 2.0 and 5.0 wt% and at various flow rates ranging from 250 to 1000 µl/min. Both experimental measurements and numerical analyses are employed to obtain the convective heat transfer coefficient. The results indicate a significant enhancement in convective heat transfer coefficient due to the implementation of microparticle suspensions. For the case of Al2O3 microparticle suspension with 5.0 wt% concentration, a 20.3 % enhancement in convective heat transfer coefficient is obtained over deionised water. This is comparable to the case of Al2O3 nanofluid at the same concentration. Hence, there is a potential for the microparticle suspensions to be used for cooling of compact integrated systems.

  11. Enhancement of laminar convective heat transfer using microparticle suspensions

    Science.gov (United States)

    Zhu, Jiu Yang; Tang, Shiyang; Yi, Pyshar; Baum, Thomas; Khoshmanesh, Khashayar; Ghorbani, Kamran

    2017-01-01

    This paper investigates the enhancement of convective heat transfer within a sub-millimetre diameter copper tube using Al2O3, Co3O4 and CuO microparticle suspensions. Experiments are conducted at different particle concentrations of 1.0, 2.0 and 5.0 wt% and at various flow rates ranging from 250 to 1000 µl/min. Both experimental measurements and numerical analyses are employed to obtain the convective heat transfer coefficient. The results indicate a significant enhancement in convective heat transfer coefficient due to the implementation of microparticle suspensions. For the case of Al2O3 microparticle suspension with 5.0 wt% concentration, a 20.3 % enhancement in convective heat transfer coefficient is obtained over deionised water. This is comparable to the case of Al2O3 nanofluid at the same concentration. Hence, there is a potential for the microparticle suspensions to be used for cooling of compact integrated systems.

  12. Effect of water flow rate on the heat transfer coefficient of a hot steel plate during laminar flow cooling%水流量对热轧钢板层流冷却过程对流换热系数的影响

    Institute of Scientific and Technical Information of China (English)

    汪贺模; 蔡庆伍; 余伟; 苏岚

    2012-01-01

    Establishing an accuracy relationship between the convective heat transfer coefficient and cooling process is the key to improve the laminar cooling control model, The convective heat transfer coefficient and corresponding surface temperature were calculated by the finite difference method and the inverse heat conduction method. The effects of cooling water jet flow rate on the heat transfer coefficient and surface temperature was investigated when the cooling water jet flow rate varied from 0. 9 to 2, 1 m3 · h -1. It is found that the convective heat transfer coefficient is a nonlinear function of the surface temperature during laminar flow cooling. Within a distance of 70 mm from the stagnation line, the cooling flow rate has no effect on the heat transfer coefficient and surface temperature. But outside 70 mm, the heat transfer coefficient ratio becomes smaller with increasing distance from the stagnation line, It is also shown that relatively good agreement is obtained between the calculated and measured curves.%提高带钢层流冷却控制模型的精度,关键是建立精确的对流换热系数与冷却工艺之间的关系.采用有限差分法和反向热传导法,获得了实验条件下钢板表面的对流换热系数及表面温度.研究了不同水流量(0.9—2.1m3·h-1)对换热系数与表面温度变化规律的影响.在层流冷却过程中,对流换热系数与表面温度呈非线性关系;在距离驻点70mm内,水流量对换热系数随表面温度变化规律没影响;远离驻点70mm外,对流换热系数比随远离冲击区驻点距离的增加而减小.采用所确定的换热系数计算得到的温降曲线与实测曲线吻合较好.

  13. Dropwise Evaporative Cooling of Heated Surfaces with Various Wettability Characteristics Obtained by Nanostructure Modifications.

    Science.gov (United States)

    Chen, Jian-Nan; Zhang, Zhen; Ouyang, Xiao-Long; Jiang, Pei-Xue

    2016-12-01

    A numerical and experimental investigation was conducted to analyze dropwise evaporative cooling of heated surfaces with various wettability characteristics. The surface wettability was tuned by nanostructure modifications. Spray-cooling experiments on these surfaces show that surfaces with better wettability have better heat transfer rate and higher critical heat flux (CHF). Single droplet impingement evaporative cooling of a heated surface was then investigated numerically with various wettability conditions to characterize the effect of contact angle on spray-cooling heat transfer. The volume of fluid (VOF) model with variable-time stepping was used to capture the time-dependent liquid-gas interface motion throughout the computational domain with the kinetic theory model used to predict the evaporation rate at the liquid-gas interface. The numerical results agree with the spray-cooling experiments that dropwise evaporative cooling is much better on surfaces with better wettability because of the better liquid spreading and convection, better liquid-solid contact, and stronger liquid evaporation.

  14. Heat Transfer in an L Shaped Porous Medium using FEM

    Science.gov (United States)

    Anjum Badruddin, Irfan; Yunus Khan, T. M.

    2017-08-01

    Heat transfer in porous medium has been an intense field of study for many years that has tremendously improved our understanding about the heat flow behavior in porous region. Finite element method has been widely acknowledged to be one of the most robust numerical techniques that has proven its capability in handling the tedious and complex set of equations representing various phenomenon. The present research investigates the heat transfer inside a L shaped porous domain having heated from bottom surface and cooled at the top edge. Finite element method is used with the help of triangular element to divide the porous domain into smaller segments. The results are discussed with respect to various physical parameters affecting the heat transfer behaviour.

  15. Nanofluids for heat transfer: an engineering approach.

    Science.gov (United States)

    Timofeeva, Elena V; Yu, Wenhua; France, David M; Singh, Dileep; Routbort, Jules L

    2011-02-28

    An overview of systematic studies that address the complexity of nanofluid systems and advance the understanding of nanoscale contributions to viscosity, thermal conductivity, and cooling efficiency of nanofluids is presented. A nanoparticle suspension is considered as a three-phase system including the solid phase (nanoparticles), the liquid phase (fluid media), and the interfacial phase, which contributes significantly to the system properties because of its extremely high surface-to-volume ratio in nanofluids. The systems engineering approach was applied to nanofluid design resulting in a detailed assessment of various parameters in the multivariable nanofluid systems. The relative importance of nanofluid parameters for heat transfer evaluated in this article allows engineering nanofluids with desired set of properties.

  16. Nanofluids for heat transfer: an engineering approach

    Directory of Open Access Journals (Sweden)

    France David

    2011-01-01

    Full Text Available Abstract An overview of systematic studies that address the complexity of nanofluid systems and advance the understanding of nanoscale contributions to viscosity, thermal conductivity, and cooling efficiency of nanofluids is presented. A nanoparticle suspension is considered as a three-phase system including the solid phase (nanoparticles, the liquid phase (fluid media, and the interfacial phase, which contributes significantly to the system properties because of its extremely high surface-to-volume ratio in nanofluids. The systems engineering approach was applied to nanofluid design resulting in a detailed assessment of various parameters in the multivariable nanofluid systems. The relative importance of nanofluid parameters for heat transfer evaluated in this article allows engineering nanofluids with desired set of properties.

  17. Nanofluids for heat transfer : an engineering approach.

    Energy Technology Data Exchange (ETDEWEB)

    Timofeeva, E. V.; Yu, W.; France, D. M.; Singh, D.; Routbort, J. L. (Energy Systems); ( NE); (Univ. of Illinois at Chicago)

    2011-02-28

    An overview of systematic studies that address the complexity of nanofluid systems and advance the understanding of nanoscale contributions to viscosity, thermal conductivity, and cooling efficiency of nanofluids is presented. A nanoparticle suspension is considered as a three-phase system including the solid phase (nanoparticles), the liquid phase (fluid media), and the interfacial phase, which contributes significantly to the system properties because of its extremely high surface-to-volume ratio in nanofluids. The systems engineering approach was applied to nanofluid design resulting in a detailed assessment of various parameters in the multivariable nanofluid systems. The relative importance of nanofluid parameters for heat transfer evaluated in this article allows engineering nanofluids with desired set of properties.

  18. 46 CFR 190.20-50 - Heating and cooling.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Heating and cooling. 190.20-50 Section 190.20-50... CONSTRUCTION AND ARRANGEMENT Accomodations for Officers, Crew, and Scientific Personnel § 190.20-50 Heating and... the space. (b) Radiators and other heating apparatus must be so placed and shielded, where...

  19. Evaluation of immersion coil designs for natural convection-driven batch cooling or heating in tanks

    Energy Technology Data Exchange (ETDEWEB)

    Joye, Donald D.; Smith, Michael A.

    2000-09-01

    Various designs of immersion coils for batch cooling or heating of liquids in tanks were investigated to determine which design was most efficient. This equipment has direct utility in chemical batch processing operations and, particularly, wort cooling - a critical step in small-scale batch brewing of beer. This operation does not use a stirrer or agitation for a variety of reasons, hence it is dependent on natural-convection mechanisms for heat transfer, yet quick cooling is desired. Four basic coil designs with several permutations were evaluated. The results fell into four groups - best, good, mediocre, and worst performers. We found that coil placement and shape were design parameters that had a critical effect on the rate of cooling. Coil spacing also had a significant effect on the cooling rate when it was less than about 2 diameters. (Author)

  20. Coloration affects heating and cooling in three color morphs of the Australian bluetongue lizard, Tiliqua scincoides.

    Science.gov (United States)

    Geen, Michael R S; Johnston, Gregory R

    2014-07-01

    The color-mediated thermoregulation hypothesis predicts that dark body color (low reflectance) allows organisms to gain heat more efficiently than does pale coloration (high reflectance). This prediction is intuitive and widely assumed to be true, but has poor empirical support. We used rare, captive-bred, mutant melanistic, albino and wild-type Australian bluetongue lizards, Tiliqua scincoides to measure the effects of skin reflectance on the heating and cooling rates. We measured heating under an artificial radiant heat source and cooling rates in an ice-cooled box using live lizards in a room with still air. The effect of skin reflectance on heat transfer was clear, despite the substantial influence of body size. Melanistic T. scincoides showed low reflectance and gained heat faster than highly reflective albinos. Melanistic lizards also lost heat faster than albinos. Wild-type lizards were intermediate in reflectance, gained heat at rates indistinguishable from melanistic lizards, and lost heat at rates indistinguishable from albino lizards. This study system allowed us to control for variables that were confounded in other studies and may explain the inconsistent support for the color-mediated thermoregulation hypothesis. Our results provide clear evidence that skin reflectance influences the rate of heating and cooling in ectotherms.

  1. Two-Pipe Chilled Beam System for Both Cooling and Heating of Office Buildings

    DEFF Research Database (Denmark)

    Afshari, Alireza; Gordnorouzi, Rouzbeh; Hultmark, Göran;

    2013-01-01

    advantage of renewable energy. The results showed that the energy consumption was 3% less in the 2-pipe chilled beam system in comparison with the conventional 4-pipe system when moving cooled and heated water through the building, transferring the energy to where it is needed. Using free cooling (taking...... consumption and hence energy savings in the 2-pipe chilled beam system in comparison with the 4-pipe system. The 2-pipe chilled beam system used high temperature cooling and low temperature heating with a water temperature of 20°C to 23°C, available for free most of the year. The system can thus take......Simulations were performed to compare a conventional 4-pipe chilled beam system and a 2-pipe chilled beam system. The objective was to establish requirements, possibilities and limitations for a well-functioning 2-pipe chilled beam system for both cooling and heating of office buildings...

  2. The Influence of Knitting Structure on Heating and Cooling Dynamic

    Directory of Open Access Journals (Sweden)

    Daiva MIKUČIONIENĖ

    2013-05-01

    Full Text Available The comfort provided by clothing depends on several factors, one of them being thermal comfort. Human thermal comfort depends on a combination of clothing, climate, and physical activity. It is known, the fibre type, yarn properties, fabric structure, finishing are the main factors affecting thermo-physiological comfort. The thermal property of knitted fabric is very important not only for its thermal comfort but also for protection against cross weather conditions. Most of the studies carried out have been devoted to measure static thermal properties. But it is very important not only amount of the heat released to the environment but also the dynamics of the heat transmission. The main goal of this work was to investigate the dynamic of the heat and cool transfer through the fabrics with different knitting pattern and different type of the yarns. Three different types of knitted fabrics were developed for this experimental work.DOI: http://dx.doi.org/10.5755/j01.ms.19.2.4434

  3. The Influence of Knitting Structure on Heating and Cooling Dynamic

    Directory of Open Access Journals (Sweden)

    Daiva MIKUČIONIENĖ

    2013-05-01

    Full Text Available The comfort provided by clothing depends on several factors, one of them being thermal comfort. Human thermal comfort depends on a combination of clothing, climate, and physical activity. It is known, the fibre type, yarn properties, fabric structure, finishing are the main factors affecting thermo-physiological comfort. The thermal property of knitted fabric is very important not only for its thermal comfort but also for protection against cross weather conditions. Most of the studies carried out have been devoted to measure static thermal properties. But it is very important not only amount of the heat released to the environment but also the dynamics of the heat transmission. The main goal of this work was to investigate the dynamic of the heat and cool transfer through the fabrics with different knitting pattern and different type of the yarns. Three different types of knitted fabrics were developed for this experimental work.DOI: http://dx.doi.org/10.5755/j01.ms.19.2.4434

  4. Heat transfer coeffcient for boiling carbon dioxide

    DEFF Research Database (Denmark)

    Knudsen, Hans Jørgen Høgaard; Jensen, Per Henrik

    1997-01-01

    transfer coefficient but the ratio between the measured and the calculated heat transfer coefficient is nearly constant and equal 1.9. With this factor the correlation predicts the measured data within 14% (RMS). The pressure drop is of the same order as the measuring uncertainty and the pressure drop has......Heat transfer coefficient and pressure drop for boiling carbon dioxide (R744) flowing in a horizontal pipe has been measured. The pipe is heated by condensing R22 outside the pipe. The heat input is supplied by an electrical heater wich evaporates the R22. With the heat flux assumed constant over...... the whole surface and with measured temperature difference between the inner surface and the evaporation temperature a mean heat transfer coefficient is calculated. The calculated heat transfer coefficient has been compared with the Chart Correlation of Shah. The Chart Correlation predicts too low heat...

  5. Heat Transfer in Complex Fluids

    Energy Technology Data Exchange (ETDEWEB)

    Mehrdad Massoudi

    2012-01-01

    fluids show Newtonian (linear) behavior for a given range of parameters or geometries; there are many empirical or semi-empirical constitutive equations suggested for these fluids. There have also been many non-linear constitutive relations which have been derived based on the techniques of continuum mechanics. The non-linearities oftentimes appear due to higher gradient terms or time derivatives. When thermal and or chemical effects are also important, the (coupled) momentum and energy equations can give rise to a variety of interesting problems, such as instability, for example the phenomenon of double-diffusive convection in a fluid layer. In Conclusion, we have studied the flow of a compressible (density gradient type) non-linear fluid down an inclined plane, subject to radiation boundary condition. The heat transfer is also considered where a source term, similar to the Arrhenius type reaction, is included. The non-dimensional forms of the equations are solved numerically and the competing effects of conduction, dissipation, heat generation and radiation are discussed. It is observed that the velocity increases rapidly in the region near the inclined surface and is slower in the region near the free surface. Since R{sub 7} is a measure of the heat generation due to chemical reaction, when the reaction is frozen (R{sub 7}=0.0) the temperature distributions would depend only on R{sub 1}, and R{sub 2}, representing the effects of the pressure force developed in the material due to the distribution, R{sub 3} and R{sub 4} viscous dissipation, R{sub 5} the normal stress coefficient, R{sub 6} the measure of the emissivity of the particles to the thermal conductivity, etc. When the flow is not frozen (RP{sub 7} > 0) the temperature inside the flow domain is much higher than those at the inclined and free surfaces. As a result, heat is transferred away from the flow toward both the inclined surface and the free surface with a rate that increases as R{sub 7} increases. For a

  6. Engineering calculations in radiative heat transfer

    CERN Document Server

    Gray, W A; Hopkins, D W

    1974-01-01

    Engineering Calculations in Radiative Heat Transfer is a six-chapter book that first explains the basic principles of thermal radiation and direct radiative transfer. Total exchange of radiation within an enclosure containing an absorbing or non-absorbing medium is then described. Subsequent chapters detail the radiative heat transfer applications and measurement of radiation and temperature.

  7. An analytical comparison of convective heat transfer correlations in supercritical hydrogen

    Science.gov (United States)

    Dziedzic, William M.; Jones, Stuart C.; Gould, Dana C.; Petley, Dennis H.

    1991-01-01

    Four correlations that cover the ranges of liquid to gas for turbulent flow convection of hydrogen are compared with CFD analysis over a range of expected design conditions for active cooling of hypersonic aircraft. Analysis of hydrogen cooling in a typical cooling panel shows how predicted design performance varies with the correlation utilized. The CFD heat transfer coefficient results for a heat spike differed significantly from all four correlations. An acceptable heat transfer coefficient can be calculated at the heat spike location by overlooking the coefficient at the spike and averaging the coefficient before and after the spike.

  8. Science 101: What Are the Earth's Heating and Cooling Mechanisms?

    Science.gov (United States)

    Robertson, Bill

    2015-01-01

    In this article, author Bill Robertson attempts to help readers understand some of the Earth's heating and cooling mechanisms and how they relate to global warming. Figures are provided to help facilitate learning.

  9. Change in Annual Heating and Cooling Degree Days by State

    Data.gov (United States)

    U.S. Environmental Protection Agency — This service show changes in heating and cooling degree days by state in the US. Both layers in this service were created by comparing the first 60 years of...

  10. Identification of Heat Transfer Coefficients by Use Conditions of Quenching Oil

    Institute of Scientific and Technical Information of China (English)

    Katsumi Ichitani

    2004-01-01

    Heat transfer coefficients of the quench medium are necessary for heat-treatment simulation. Cooling characteristics of quenching oil vary with kinds and usage greatly. Users are selecting oil solutions that come up to their desired hardness and quenching distortion requirements. In particular cooling performance rises by agitation and decompression. Therefore we identified a heat transfer coefficient by usage and kinds of quenching oil. Cooling characteristics are different greatly by a kind of quenching oil. A difference of a cooling characteristic by a kind of oil depends on a temperature range of a boiling stage and the maximum heat transfer coefficient mainly. On the other hand, in a convection stage, there are few changes in a boiling stage. Even if quenching oil temperature is changed, heat transfer coefficients do not change greatly. When quenching oil stirred, heat transfer coefficients of vapor blanket stage and a convection stage rise, but there are a few changes in a boiling stage. When quenching oil is decompressed a temperature range of a high heat transfer coefficient moves to the low temperature side. In addition, a heat transfer coefficient in a vapor blanket stage comes down. For precision improvement of heat-treatment simulation, it is important that the heat transfer coefficient is calculated in conformity to the on-site use reality.

  11. Water chemistry in heat and cold supply (district heating/cooling)

    Energy Technology Data Exchange (ETDEWEB)

    Deelen-Bremer, Marga van; Vos, Frank de; Heijboer, Rob [KEMA Nederland B.V. (Netherlands)

    2010-07-01

    District heating is seen as an important pillar in the CO{sub 2} reduction. Since the Kyoto protocol with the target for reduction of greenhouse gases, a renewed interest in district heating is visible. District heating and increasingly district cooling can be used for heating/cooling of houses, but also for large buildings and greenhouses. Combined heat and power (CHP), waste incinerator, but also rest heat of industry can provide the heat for district heating. On the other hand cold surface water, groundwater, but also rest heat can be used for district cooling. With the growing heat/cold supply market, also an even larger growth in cases of damages in district heating systems is wittnessed. Damages were chemistry can play an preventing role. A good conditioning of the district heating water, combined with proper monitoring, will safeguard the integrity of the system. (orig.)

  12. Augmentation of Cooling Output by Silica Gel-Water Adsorption Cycle Utilizing the Waste Heat of GHP

    Science.gov (United States)

    Homma, Hiroki; Araki, Nobuyuki

    The GHP (Gas engine Heat Pump) system is expected to have high energy-efficiency in utilizing the waste heat exhausted from a gas engine. In summer season, a silica gel-water adsorption cooling unit driven by the exhaust heat is considered as a cooling system for saving energy. In this work, an attempt was made to improve the COP of a silica gel-water adsorption cooling system by enhancing heat and mass transfer in the silica gel adsorption layer. A unit cell was introduced as a simplified model of adsorber for analyzing the phenomena of heat and mass transfer in the adsorbent. This cell was composed of a single tube with a silica gel layer bonded on its external surface. Optimization of heat and mass transfer characteristics for the unit cell was carried out by experimental and analytical approach.

  13. Comparisons of Heat Transfer Performance of a Closed-looped Oscillating Heat Pipe and Closed-looped Oscillating Heat Pipe with Check Valves Heat Exchangers

    Directory of Open Access Journals (Sweden)

    P. Meena

    2008-01-01

    Full Text Available This research was to study the comparisons of heat transfer performance of closed-looped oscillating heat pipe and closed-looped oscillating heat pipe with check valves heat exchangers with R134a, Ethanol and water were used as the working fluids. A set of heat pipe heat exchanger (CLOHP and CLOHP/CV were made of copper tubes in combination of following dimension: 2.03 mm inside diameter: 40 turns, with 20, 10 and 20 cm for evaporator, adiabatic and condenser sections lengths. The working fluid was filled in the tube at the filling ratio of 50%. The evaporator section was given heat by heater while the condenser section was cooled by air. The adiabatic section was properly insulated. In the test operation, it could be concluded as follows. It indicated that the heat transfer performance of closed-looped oscillating heat pipe with check valves heat exchanger better than closed-looped oscillating heat exchanger.

  14. Change of heat transfer- and mass transfer-coefficients with simultaneous heat- and mass transfer

    Energy Technology Data Exchange (ETDEWEB)

    Kast, W.

    1981-01-01

    The values of sensible and latent heat and of the resulting energy flow through laminar boundary layer have been developed for the four possible combinations of the directions of heat- and mass flows. When the values of heat- and mass flows are used with the correct sign according to the definitions of Fourier's law and Fick's law, the changes of heat transfer- and mass transfer coefficients can be described by one equation alone for all cases. The equations extended in that way are valid for arbitrary cases of countercurrent diffusing mass flows - not only for the well known case of Stefan diffusion.

  15. Solar heat for cooling; Kampf der Kaelte

    Energy Technology Data Exchange (ETDEWEB)

    Janzing, Bernward

    2011-05-15

    Solar cooling systems have been in use for several years now. The energy saving potential is enormous, but there is also much to be learned. Careful planning is required as well as early retrofitting or replacement of existing systems.

  16. District heating and cooling technology selection and characterization. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Metz, P.D.; Catan, M.; Piraino, M.; Timmerman, R.W.; Gleason, J.

    1986-03-01

    This report describes the district heating and cooling (DHC) technology selection and characterization tasks performed under Part I of the project ''District Heating and Cooling Market Potential and Penetration Study'' for the USDOE. The purpose of this project is to determine the applicability of various DHC technologies to different community types and regions of the country. The results will be used by DOE to guide R and D program planning.

  17. Compact star cooling by means of heat waves

    Directory of Open Access Journals (Sweden)

    Nelson Falcón

    2001-01-01

    Full Text Available Compact star cooling theory is revised using the Cattaneo law for the heat flux. It is shown changes in the energy transport equation, insinuates quasiperiodic pulses in the luminosity and predicts that the energy is spread by heat waves changing the cooling time. Applications in rapid variations in single white-dwarf oscillators and quasi periodic luminosity pulses of neutron stars are suggested.

  18. Evaluation of Heat Removal from RBMK-1500 Core Using Control Rods Cooling Circuit

    Directory of Open Access Journals (Sweden)

    A. Kaliatka

    2008-01-01

    Full Text Available The Ignalina nuclear power plant is a twin unit with two RBMK-1500, graphite moderated, boiling water, multichannel reactors. After the decision was made to decommission the Ignalina NPP, Unit 1 was shut down on December 31, 2004, and Unit 2 is to be operated until the end of 2009. Despite of this fact, severe accident management guidelines for RBMK-1500 reactor at Ignalina NPP are prepared. In case of beyond design basis accidents, it can occur that no water sources are available at the moment for heat removal from fuel channels. Specificity of RBMK reactor is such that the channels with control rods are cooled with water supplied by the system totally independent from the reactor cooling system. Therefore, the heat removal from RBMK-1500 reactor core using circuit for cooling of rods in control and protection system can be used as nonregular mean for reactor cooldown in case of BDBA. The heat from fuel channels, where heat is generated, through graphite bricks is transferred in radial direction to cooled CPS channels. This article presents the analysis of possibility to remove heat from reactor core in case of large LOCA by employing CPS channels cooling circuit. The analysis was performed for Ignalina NPP with RBMK-1500 reactor using RELAP5-3D and RELAP5 codes. Results of the analysis have shown that, in spite of high thermal inertia of graphite, this heat removal from CPS channels allows to slow down effectively the core heat-up process.

  19. Boiling Heat Transfer in Circulating Fluidized Beds

    Institute of Scientific and Technical Information of China (English)

    张利斌; 李修伦

    2001-01-01

    A model is proposed to predict boiling heat transfer coefficient in a three-phase circulating fluidized bed (CFB), which is a new type of evaporation boiling means for enhancing heat transfer and preventing fouling. To verify the model, experiments are conducted in a stainless steel column with 39 mm ID and 2.0 m height, in which the heat transfer coefficient is measured for different superficial velocities, steam pressures, particle concentrations and materials of particle. As the steam pressure and particle concentrations increase, the heat transfer coefficient in the bed increases. The heat transfer coefficient increases with the liquid velocity but it exhibits a local minimum.The heat transfer coefficient is correlated with cluster renewed model and two-mechanism method. The prediction of the model is in good agreement with experimental data.

  20. Boiling Heat Transfer in Circulating Fluidized Beds

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A model is proposed to predict boiling heat transfer coefficient in a three-phase circulating fluidized bed (CFB), which is a new type of evaporation boiling means for enhancing heat transfer and preventing fouling. To verify the model, experiments are conducted in a stainless steel column with 39mm ID and 2.0m height, in which the heat transfer coefficient is measured for different superficial velocities, steam pressures, particle concentrations and materials of particle. As the steam pressure and particle concentrations increase, the heat transfer coefficient in the bed increases. The heat transfer coefficient increases with the liquid velocity but it exhibits a local minimum. The heat transfer coefficient is correlated with cluster renewed model and two-mechanism method. The prediction of the model is in good agreement with experimental data.

  1. Directly connected heat exchanger tube section and coolant-cooled structure

    Energy Technology Data Exchange (ETDEWEB)

    Chainer, Timothy J.; Coico, Patrick A.; Graybill, David P.; Iyengar, Madhusudan K.; Kamath, Vinod; Kochuparambil, Bejoy J.; Schmidt, Roger R.; Steinke, Mark E.

    2015-09-15

    A method is provided for fabricating a cooling apparatus for cooling an electronics rack, which includes an air-to-liquid heat exchanger, one or more coolant-cooled structures, and a tube. The heat exchanger is associated with the electronics rack and disposed to cool air passing through the rack, includes a plurality of coolant-carrying tube sections, each tube section having a coolant inlet and outlet, one of which is coupled in fluid communication with a coolant loop to facilitate flow of coolant through the tube section. The coolant-cooled structure(s) is in thermal contact with an electronic component(s) of the rack, and facilitates transfer of heat from the component(s) to the coolant. The tube connects in fluid communication one coolant-cooled structure and the other of the coolant inlet or outlet of the one tube section, and facilitates flow of coolant directly between that coolant-carrying tube section of the heat exchanger and the coolant-cooled structure.

  2. Heat transfer in porous media

    Directory of Open Access Journals (Sweden)

    N. Amanifard

    2007-06-01

    Full Text Available In this work, the effects of electrical double layer (EDL near the solid/ liquid interface, on three dimensional heat transfer characteristic and pressure drop of water flow through a rectangular microchannel numerically are investigated. An additional body force originating from the existence of EDL is considered to modify the conventional Navier-stokes and energy equations. These modified equations are solved numerically for steady laminar flow on the basis of control volume approaches. Fluid velocity distribution and temperature with presence and absence of EDL effects are presented for various geometric cases and different boundary conditions. The results illustrate that, the liquid flow in rectangular microchannels is influenced significantly by the EDL, particularly in the high electric potentials, and hence deviates from flow characteristics described by classical fluid mechanics.

  3. Thermal Regulation of Heat Transfer Processes

    Science.gov (United States)

    2014-10-02

    be approximately 320 m2g-1, 32 times higher than graphite flakes for more efficient heat transfer to the fluid. The evaporation rates of water...AFRL-OSR-VA-TR-2014-0249 THERMAL REGULATION OF HEAT TRANSFER PROCESSES GANG CHEN MASSACHUSETTS INSTITUTE OF TECHNOLOGY Final Report 10/02/2014...Prescribed by ANSI Std. Z39.18 FINAL REPORT FOR FA9550-11-1-0174 THERMAL REGULATION OF HEAT TRANSFER PROCESSES Principal Investigator: Gang Chen

  4. Radiative heat transfer between metallic nanoparticles

    OpenAIRE

    Chapuis, Pierre-Olivier; Laroche, Marine; Volz, Sebastian; Greffet, Jean-Jacques

    2008-01-01

    International audience; In this letter, we study the radiative heat transfer between two nanoparticles in the near field and in the far field. We find that the heat transfer is dominated by the electric dipole-dipole interaction for dielectric particles and by the magnetic dipole-dipole interaction for metallic nanoparticles. We introduce polarizabilities formulas valid for arbitrary values of the skin depth. While the heat transfer mechanism is different for metallic and dielectric nanoparti...

  5. Finite element simulation of heat transfer

    CERN Document Server

    Bergheau, Jean-Michel

    2010-01-01

    This book introduces the finite element method applied to the resolution of industrial heat transfer problems. Starting from steady conduction, the method is gradually extended to transient regimes, to traditional non-linearities, and to convective phenomena. Coupled problems involving heat transfer are then presented. Three types of couplings are discussed: coupling through boundary conditions (such as radiative heat transfer in cavities), addition of state variables (such as metallurgical phase change), and coupling through partial differential equations (such as electrical phenomena).? A re

  6. Heat Transfer and Cooling in Gas Turbines

    Science.gov (United States)

    1985-09-01

    and the Re, it is not surprising that the lao/ luc ratio (Figure 14) shows a dependency on y and Re as well. The ratio of the friction factors (fro/frc...obtained using a flat-plate correlation, a two-dimensional parabolic boundary layer code (STAN5), and a three-dimensional viscous code ( NANCY I). The...29-1 PYROMETRE OPTIQUE INFRAROUGE POUR LA MLSURE DFS IEMPERATURES DAUBES DE TURBINE par Marc Charpenel and Jean Wilhern ONERA 29 Ave itue de

  7. Heat-transfer data for hydrogen

    Science.gov (United States)

    Mc Carthy, J. R.; Miller, W. S.; Okuda, A. S.; Seader, J. D.

    1970-01-01

    Information is given regarding experimental heat-transfer data compiled for the turbulent flow of hydrogen within straight, electrically heated, round cross section tubes. Tube materials, test conditions, parameters studied, and generalized conclusions are presented.

  8. Base fluid in improving heat transfer for EV car battery

    Science.gov (United States)

    Bin-Abdun, Nazih A.; Razlan, Zuradzman M.; Shahriman, A. B.; Wan, Khairunizam; Hazry, D.; Ahmed, S. Faiz; Adnan, Nazrul H.; Heng, R.; Kamarudin, H.; Zunaidi, I.

    2015-05-01

    This study examined the effects of base fluid (as coolants) channeling inside the heat exchanger in the process of the increase in thermal conductivity between EV car battery and the heat exchanger. The analysis showed that secondary cooling system by means of water has advantages in improving the heat transfer process and reducing the electric power loss on the form of thermal energy from batteries. This leads to the increase in the efficiency of the EV car battery, hence also positively reflecting the performance of the EV car. The present work, analysis is performed to assess the design and use of heat exchanger in increasing the performance efficiency of the EV car battery. This provides a preface to the use this design for nano-fluids which increase and improve from heat transfer.

  9. Selection of Rational Heat Transfer Intensifiers in the Heat Exchanger

    Directory of Open Access Journals (Sweden)

    S. A. Burtsev

    2016-01-01

    Full Text Available The paper considers the applicability of different types of heat transfer intensifiers in the heat exchange equipment. A review of the experimental and numerical works devoted to the intensification of the dimpled surface, surfaces with pins and internally ribbed surface were presented and data on the thermal-hydraulic characteristics of these surfaces were given. We obtained variation of thermal-hydraulic efficiency criteria for 4 different objective functions and 15 options for the intensification of heat transfer. This makes it possible to evaluate the advantages of the various heat transfer intensifiers. These equations show influence of thermal and hydraulic characteristics of the heat transfer intensifiers (the values of the relative heat transfer and drag coefficients on the basic parameters of the shell-and-tube heat exchanger: the number and length of the tubes, the volume of the heat exchanger matrix, the coolant velocity in the heat exchanger matrix, coolant flow rate, power to pump coolant (or pressure drop, the amount of heat transferred, as well as the average logarithmic temperature difference. The paper gives an example to compare two promising heat transfer intensifiers in the tubes and shows that choosing the required efficiency criterion to search for optimal heat exchanger geometry is of importance. Analysis is performed to show that a dimpled surface will improve the effectiveness of the heat exchanger despite the relatively small value of the heat transfer intensification, while a significant increase in drag of other heat transfer enhancers negatively affects their thermalhydraulic efficiency. For example, when comparing the target functions of reducing the heat exchanger volume, the data suggest that application of dimpled surfaces in various fields of technology is possible. But there are also certain surfaces that can reduce the parameters of a heat exchanger. It is shown that further work development should be aimed at

  10. Heat transfer tests conducted on full-scale model, to investigate cooling conditions of EL.3 experimental reactor; Essais de transmission de chaleur sur maquette pour l'etude du refroidissement de la pile EL 3

    Energy Technology Data Exchange (ETDEWEB)

    Raievski, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Butzbach, M.; Domenjoud, M. [Alsthom, 75 - Paris (France); Bousquet, M. [Chantiers de l' Atlantique (France); Braudeau, M.; Milliat, M. [Electricite de France (EDF), 75 - Paris (France)

    1958-07-01

    For such high heat flux density as is released in the channels of EL3 reactor (2.10{sup 6} kcal/m{sup 2}h on the hottest point) cooling conditions have proved to be satisfactory, that is free from nucleate boiling. The arrangements provided for these tests and the technique used for measurements (of temperature particularly) are specified. Two fields have been investigated: in the former (forced convection without nucleate boiling) a good agreement is found with Colburn's formula. The influence of the ratio L/D is pointed out. The latter field is of forced convection with beginning of nucleate boiling; there the observed raise of the transfer coefficient has been shown occurring with some delay. (author)Fren. [French] A la valeur elevee prevue pour la densite de flux de chaleur (2.10{sup 6} kcal/m{sup 2}h au point le plus chaud) il est verifie que le refroidissement de la pile s'effectue normalement (sans ebullition de paroi). Les essais sont menes sur la maquette grandeur nature d'un canal d'EL3. Les dispositions relatives a la conduite des essais et a la technique des mesures (de temperature en particulier) sont precisees. Deux domaines sont etudies; pour t{sub p} < T{sub sat} (convection forcee sans ebullition de paroi) on constate un bon accord avec la formule de Colburn, avec toutefois l'influence du rapport L/D. Pour t{sub p} < T{sub sat} (debut d'ebullition) l'augmentation prevue du coefficient de transmission presente un certain retard. (auteur)

  11. Heat transfer coeffcient for boiling carbon dioxide

    DEFF Research Database (Denmark)

    Knudsen, Hans Jørgen Høgaard; Jensen, Per Henrik

    1997-01-01

    Heat transfer coefficient and pressure drop for boiling carbon dioxide (R744) flowing in a horizontal pipe has been measured. The pipe is heated by condensing R22 outside the pipe. The heat input is supplied by an electrical heater wich evaporates the R22. With the heat flux assumed constant over...

  12. Heat transfer coefficient for boiling carbon dioxide

    DEFF Research Database (Denmark)

    Knudsen, Hans Jørgen Høgaard; Jensen, Per Henrik

    1998-01-01

    between the measured and the calculated heat transfer coefficient is nearly constant and equal 1.9. With this factor the correlation predicts the measured data within 14% (RMS). The pressure drop is of the same order as the measuring uncertainty and the pressure drop has not been compared with correlation's.......Heat transfer coefficient and pressure drop for boiling carbon dioxide (R744) flowing in a horizontal pipe has been measured. The calculated heat transfer coeeficient has been compared with the Chart correlation of Shah. The Chart Correlation predits too low heat transfer coefficient but the ratio...

  13. Radiative heat transfer in porous uranium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, S.L. [Texas A and M Univ., College Station, TX (United States)

    1992-12-01

    Due to low thermal conductivity and high emissivity of UO{sub 2}, it has been suggested that radiative heat transfer may play a significant role in heat transfer through pores of UO{sub 2} fuel. This possibility was computationally investigated and contribution of radiative heat transfer within pores to overall heat transport in porous UO{sub 2} quantified. A repeating unit cell was developed to model approximately a porous UO{sub 2} fuel system, and the heat transfer through unit cells representing a wide variety of fuel conditions was calculated using a finite element computer program. Conduction through solid fuel matrix as wekk as pore gas, and radiative exchange at pore surface was incorporated. A variety of pore compositions were investigated: porosity, pore size, shape and orientation, temperature, and temperature gradient. Calculations were made in which pore surface radiation was both modeled and neglected. The difference between yielding the integral contribution of radiative heat transfer mechanism to overall heat transport. Results indicate that radiative component of heat transfer within pores is small for conditions representative of light water reactor fuel, typically less than 1% of total heat transport. It is much larger, however, for conditions present in liquid metal fast breeder reactor fuel; during restructuring of this fuel type early in life, the radiative heat transfer mode was shown to contribute as much as 10-20% of total heat transport in hottest regions of fuel.

  14. Study of the Flow and Heat Transfer Characters in the Tube Sheet Cooling Chamber of a Fire Tube Waste Heat Boiler%火管式余热锅炉管板冷却室内流动传热研究

    Institute of Scientific and Technical Information of China (English)

    李超; 黄波; 代正华; 杨骥; 于广锁; 王辅臣

    2015-01-01

    气流床气化–废锅流程具有较高的热效率并可副产一定量蒸汽,适宜于整体气化联合循环(IGCC)发电或无需合成气变换的工况。文中对常用于气态/液体烃气流床气化的工业火锅式余热锅炉管板冷却室建立了三维数值模型。采用Realizable k-ε模型模拟了湍流流动过程,用离散坐标模型(DOM)计算了合成气辐射传热过程,耦合研究了流体与固体壁面间的流动和传热过程。考察了冷却水入口形式、冷却水流量和出口环隙宽度对冷却室内流动传热过程的影响。结果表明,3冷却水入口的形式能够有效改善合成气管水侧壁面的冷却效果,同时获得更均匀的冷却室内速度、温度分布。现有的2冷却水入口形式下,优化的冷却水质量流量为200 t/h。此外,在合成气管道的入口处加入刚玉套管能够使合成气管道壁面的最高温度降低106 K,有效保护合成气管端部。%Due to its high energy efficiency and steam production, the entrained-flow gasification process with the radiant and conductive cooler is suitable for the integrated gasification combined cycle (IGCC) or other processes without water gas shift unit. In this work, a 3D numerical model was established to study the characters of fluid dynamic and heat transfer of the tube sheet cooling chamber of a commercial scale fire-tube waste heat boiler, which was adopted in the gaseous/liquid hydrocarbon gasification process. The realizable k-ε model and discrete ordinate model (DOM) were employed to simulate the turbulence and syngas radiant heat transfer, respectively. The fluid-solid coupling analysis of flow and heat transfer was conducted. The effects of inlet types and mass flow of the cooling water and the width of the cooling water outlet on the velocity and temperature distribution were investigated. The results show that the 3 inlets of the cooling water is the most appropriate type in enhancing the

  15. Numerical Analysis of Lead-Bismuth-Water Direct Contact Boiling Heat Transfer

    Science.gov (United States)

    Yamada, Yumi; Takahashi, Minoru

    Direct contact boiling heat transfer of sub-cooled water with lead-bismuth eutectic (Pb-Bi) was investigated for the evaluation of the performance of steam generation in direct contact of feed water with primary Pb-Bi coolant in upper plenum above the core in Pb-Bi-cooled direct contact boiling water fast reactor. An analytical two-fluid model was developed to estimate the heat transfer numerically. Numerical results were compared with experimental ones for verification of the model. The overall volumetric heat transfer coefficient was calculated from heat exchange rate in the chimney. It was confirmed that the calculated results agreed well with the experimental result.

  16. Evaluation of a Passive Heat Exchanger Based Cooling System for Fuel Cell Applications

    Science.gov (United States)

    Colozza, Anthony J.; Burke, Kenneth A.

    2011-01-01

    Fuel cell cooling is conventionally performed with an actively controlled, dedicated coolant loop that exchanges heat with a separate external cooling loop. To simplify this system the concept of directly cooling a fuel cell utilizing a coolant loop with a regenerative heat exchanger to preheat the coolant entering the fuel cell with the coolant exiting the fuel cell was analyzed. The preheating is necessary to minimize the temperature difference across the fuel cell stack. This type of coolant system would minimize the controls needed on the coolant loop and provide a mostly passive means of cooling the fuel cell. The results indicate that an operating temperature of near or greater than 70 C is achievable with a heat exchanger effectiveness of around 90 percent. Of the heat exchanger types evaluated with the same type of fluid on the hot and cold side, a counter flow type heat exchanger would be required which has the possibility of achieving the required effectiveness. The number of heat transfer units required by the heat exchanger would be around 9 or greater. Although the analysis indicates the concept is feasible, the heat exchanger design would need to be developed and optimized for a specific fuel cell operation in order to achieve the high effectiveness value required.

  17. Heat-Bath Cooling of Spins in Amino Acids

    CERN Document Server

    Elias, Yuval; Mor, Tal; Weinstein, Yossi

    2011-01-01

    Heat-bath cooling is a component of practicable algorithmic cooling of spins, an approach which might be useful for in vivo 13C spectroscopy, in particular for prolonged metabolic processes where substrates that are hyperpolarized ex-vivo are not effective. We applied heat-bath cooling to 1,2-13C2-amino acids, using the \\alpha\\ protons to shift entropy from selected carbons to the environment. For glutamate and glycine, the polarizations of both labeled carbons were enhanced, and in other experiments the total entropy of each spin system was shown to decrease. The effect of adding Magnevist, a gadolinium contrast agent, on heat-bath cooling of glutamate was investigated.

  18. Condensation heat transfer on micro and nano structured super hydrophobic surface

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Donghyun; Hwang, Kyung Won; Park, Hyun Sun; Kim, Moo Hwan [POSTECH, Pohang (Korea, Republic of)

    2014-05-15

    Condensation phenomena occur during the PCCS operation cooling the containment through phase change heat transfer. Accordingly it is important to enhance the condensation heat transfer performance. Condensation mode is commonly classified as filmwise condensation (FWC) and dropwise condensation (DWC). DWC heat transfer performance has an order of magnitude higher than FWC heat transfer performance. In DWC process, condensed liquid droplets attach to the surface and prevent transfer of heat to the cooled surface. Generally the condensate is removed by gravity. When removal rate of condensate is high, DWC heat transfer performance will be enhanced. In terms of removal rate, superhydrophobic surface, which is recently in the spotlight, is expected to have capability to enhance the DWC heat transfer efficiency by reducing droplet size. In this study, we investigated condensation heat transfer performance on micro and nano structured superhydrophobic surface. Condensation experiments on the micro and nano structured superhydrophobic surface were carried out and compared with those on the smooth hydrophobic surface in terms of heat transfer performance and condensed droplet morphologies. Through the experiments, we found that superhydrophobicity disappeared under the condensation circumstance. As a result, heat transfer performance on the superhydro-phobic structured surface decreased compared with that on the smooth hydrophobic surface. In order to enhance the condensation heat transfer performance with superhydrophobic property, condensation mechanism on superhydrophobic surface and the conditions for sustaining superhydrophobicity should be studied more.

  19. Activated-Carbon Sorbent With Integral Heat-Transfer Device

    Science.gov (United States)

    Jones, Jack A.; Yavrouian, Andre

    1996-01-01

    Prototype adsorption device used, for example, in adsorption heat pump, to store natural gas to power automobile, or to separate components of fluid mixtures. Device includes activated carbon held together by binder and molded into finned heat-transfer device providing rapid heating or cooling to enable rapid adsorption or desorption of fluids. Concepts of design and fabrication of device equally valid for such other highly thermally conductive devices as copper-finned tubes, and for such other high-surface-area sorbents as zeolites or silicates.

  20. Conjugate heat and mass transfer in heat mass exchanger ducts

    CERN Document Server

    Zhang, Li-Zhi

    2013-01-01

    Conjugate Heat and Mass Transfer in Heat Mass Exchanger Ducts bridges the gap between fundamentals and recent discoveries, making it a valuable tool for anyone looking to expand their knowledge of heat exchangers. The first book on the market to cover conjugate heat and mass transfer in heat exchangers, author Li-Zhi Zhang goes beyond the basics to cover recent advancements in equipment for energy use and environmental control (such as heat and moisture recovery ventilators, hollow fiber membrane modules for humidification/dehumidification, membrane modules for air purification, desi

  1. Solar space heating and cooling by selective use of the components of a desiccant cooling system

    Science.gov (United States)

    Abbud, Ihsan Aladdin

    The economic advantages of by-passing various components of a desiccant cooling system under conditions not requiring their use are estimated by evaluating the annual costs of heating and cooling a commercial building in three representative U.S. cities. Life-cycle costs of systems employing solar heat for space heating and desiccant regeneration are compared with those using electric heat. The costs of purchasing and operating heating and desiccant cooling systems, with and without solar heat supply, are compared with those employing conventional heating and vapor compression cooling. The conditions under which commercial buildings can be cooled with desiccant systems at costs competitive with conventional systems are identified. A commercially available vapor compression air conditioner is used as a standard of comparison for energy consumption and room comfort. Heating and cooling requirements of the building are determined by use of the BLAST computer model in a simulation of long term system operation. Performance of the desiccant cooling system and life cycle savings obtained by its use are determined by simulation employing the TRNSYS computer model. TRNSYS compatible subroutines are developed to simulate operation of the desiccant equipment, the building, and the controllers that operate and monitor the system components. The results are presented in tabular and graphical form. This study shows that in the widely different climates represented in Los Angeles, New York, and Miami, by-passing various components in the desiccant cooling system when they are not needed is economically advantageous. Operation cost of the complete system decreased by 47.3% in Los Angeles, by 30.9% in New York City, and by 23.9% in Miami by not operating the desiccant wheel and other elements. The ventilation desiccant cooling system has major economic advantage over conventional systems under conditions of moderate humidity, as in Los Angeles and New York City. In Miami, however

  2. Beam Interaction with Thin Materials: Heat Deposition, Cooling Phenomena and Damage Limits

    CERN Document Server

    Sapinski, M

    2012-01-01

    Thin targets, inserted into particle beams can serve various purposes, starting from beam emittance measurements like in wire scanner or scintillating screens up to beam content modifications like in case of stripper foils. The mechanisms of energy deposition in a thin target for various beam types are discussed, together with properties of particles produced in this kind of interaction. The cooldown processes, from heat transfer up to cooling by sublimation, and their efficiencies are presented. Finally, damage conditions are discussed and conclusions about typical damage limits are drawn. The experiments performed with the wire scanners at CERN accelerators and a mathematical model of heating and cooling of a wire are presented.

  3. Development of hybrid solar-assisted cooling/heating system

    KAUST Repository

    Huang, B.J.

    2010-08-01

    A solar-assisted ejector cooling/heating system (SACH) was developed in this study. The SACH combines a pump-less ejector cooling system (ECS) with an inverter-type heat pump (R22) and is able to provide a stable capacity for space cooling. The ECS is driven by solar heat and is used to cool the condenser of the R22 heat pump to increase its COP and reduce the energy consumption of the compressor by regulating the rotational speed of the compressor through a control system. In a complete SACH system test run at outdoor temperature 35 °C, indoor temperature 25 °C and compressor speed 20-80 Hz, and the ECS operating at generator temperature 90 °C and condensing temperature 37 °C, the corresponding condensing temperature of the heat pump in the SACH is 24.5-42 °C, cooling capacity 1.02-2.44 kW, input power 0.20-0.98 kW, and cooling COPc 5.11-2.50. This indicates that the use of ECS in SACH can effectively reduce the condensing temperature of the heat pump by 12.6-7.3 °C and reduce the power consumption by 81.2-34.5%. The SACH can also supply heat from the heat pump. At ambient temperature from 5 °C to 35 °C, the heating COPh is in the range 2.0-3.3. © 2010 Elsevier Ltd. All rights reserved.

  4. Secondary Heating Under Quenching Cooling of Aluminum Alloys

    Science.gov (United States)

    Tsukrov, S. L.; Ber, L. B.

    2017-07-01

    Variants of secondary heating of aluminum alloys are considered, i.e., under quenching of plates in a water tank or on a horizontal quenching unit with water jet cooling, under continuous quenching of strips, and under quenching of tubes in vertical furnaces. Recommendation are given for removal or substantial reduction of the intensity of secondary heating under industrial conditions.

  5. Direct electronic measurement of Peltier cooling and heating in graphene

    NARCIS (Netherlands)

    Vera-Marun, I. J.; van den Berg, J. J.; Dejene, F. K.; van Wees, B. J.

    2016-01-01

    Thermoelectric effects allow the generation of electrical power from waste heat and the electrical control of cooling and heating. Remarkably, these effects are also highly sensitive to the asymmetry in the density of states around the Fermi energy and can therefore be exploited as probes of distort

  6. Passive ventilation systems with heat recovery and night cooling

    DEFF Research Database (Denmark)

    Hviid, Christian Anker; Svendsen, Svend

    2008-01-01

    with little energy consumption and with satisfying indoor climate. The concept is based on using passive measures like stack and wind driven ventilation, effective night cooling and low pressure loss heat recovery using two fluid coupled water-to-air heat exchangers developed at the Technical University...

  7. Solar-Heated and Cooled Office Building--Columbus, Ohio

    Science.gov (United States)

    1982-01-01

    Final report documents solar-energy system installed in office building to provide space heating, space cooling and domestic hot water. Collectors mounted on roof track Sun and concentrate rays on fluid-circulating tubes. Collected energy is distributed to hot-water-fired absorption chiller and space-heating and domestic-hot-water preheating systems.

  8. Computational Simulation of a Water-Cooled Heat Pump

    Science.gov (United States)

    Bozarth, Duane

    2008-01-01

    A Fortran-language computer program for simulating the operation of a water-cooled vapor-compression heat pump in any orientation with respect to gravity has been developed by modifying a prior general-purpose heat-pump design code used at Oak Ridge National Laboratory (ORNL).

  9. CFD ANALYSIS FOR HEAT TRANSFER BETWEEN COPPER ENCAPSULATED PHASE CHANGE MATERIAL AND HEAT TRANSFER FLUID

    National Research Council Canada - National Science Library

    M.Premkumar; S.Ramachandran

    2013-01-01

    .... In this study the analysis of heat transfer between PCM and heat transfer fluids (HTF) with Spherical and cylindrical finned encapsulations made of copper are done using computational fluid dynamic (CFD...

  10. Heat removal using microclimate foot cooling: a thermal foot manikin study.

    Science.gov (United States)

    Castellani, John W; Demes, Robert; Endrusick, Thomas L; Cheuvront, Samuel N; Montain, Scott J

    2014-04-01

    It has been proposed that microclimate cooling systems exploit the peripheral extremities because of more efficient heat transfer. The purpose of this study was to quantify, using a patented microclimate cooling technique, the heat transfer from the plantar surface of the foot for comparison to other commonly cooled body regions. A military boot was fitted with an insole embedded with a coiled, 1.27 m length of hollow tubing terminating in inlet and outlet valves. A thermal foot manikin with a surface temperature of 34 degrees C was placed in the boot and the valves were connected to a system that circulated water through the insole at a temperature of 20 degrees C and flow rate of 120 ml x min(-1). The manikin foot served as a constant heat source to determine heat transfer provided by the insole. Testing was done with the foot model dry and sweating at a rate of 500 ml x h(- 1) x m(-2). Climatic chamber conditions were 30 degrees C with 30% RH. Heat loss was approximately 4.1 +/- 0.1 and approximately 7.7 +/- 0.3 W from the dry and sweating foot models, respectively. On a relative scale, the heat loss was 3.0 W and 5.5 W per 1% (unit) body surface area, respectively, for the dry and sweating conditions. The relative heat loss afforded by plantar foot cooling was similar compared to other body regions, but the absolute amount of heat removal is unlikely to make an impact on whole body heat balance.

  11. Image Inpainting by Cooling and Heating

    DEFF Research Database (Denmark)

    Gustafsson, David Karl John; Pedersen, Kim Steenstrup; Nielsen, Mads

    2007-01-01

    We discuss a method suitable for inpainting both large scale geometric structures and stochastic texture components. We use the well-known FRAME model for inpainting. We introduce a temperature term in the learnt FRAME Gibbs distribution. By using a fast cooling scheme a MAP-like solution is found...

  12. Thermodynamic formalism of minimum heat source temperature for driving advanced adsorption cooling device

    Science.gov (United States)

    Saha, Bidyut Baran; Chakraborty, Anutosh; Koyama, Shigeru; Srinivasan, Kandadai; Ng, Kim Choon; Kashiwagi, Takao; Dutta, Pradip

    2007-09-01

    This letter presents a thermodynamic formulation to calculate the minimum driving heat source temperature of an advanced solid sorption cooling device, and it is validated with experimental data. This formalism has been developed from the rigor of the Boltzmann distribution function and the condensation approximation of adsorptive molecules. An interesting and useful finding has been established from this formalism that it is possible to construct a solid sorption refrigeration device that operates in a cycle transferring heat from a low temperature source to a heat sink with a driving heat source at a temperature close to but above ambient.

  13. Enhanced heat transfer with metal wool filled tubes

    Energy Technology Data Exchange (ETDEWEB)

    Kuzay, T.M.; Collins, J.T.; Khounsary, A.M. (Argonne National Lab., IL (USA)); Morales, G. (Argonne National Lab., IL (USA) Texas Univ., El Paso, TX (USA))

    1990-08-01

    The Advanced Photon Source (APS) to be constructed at Argonne National Laboratory (ANL) utilizes magnetic devices which generate x-ray beams with very intense heat flux levels. The flux levels encountered can be one or two orders of magnitude higher than those commonly found in nuclear reactors or fusion devices. The beam line elements and optics on such beams pose significant challenge to the researchers and designers to keep them cooled at acceptable levels of surface temperature and/or temperature gradients. Therefore, methods and techniques achieving heat removal enhancement are constantly sought. One such technique suggested and considered is the use of conductive metal wool filled tubes where the filter is brazed to the tube walls. A comparative investigation of the conventionally achievable heat transfer coefficient h'' with water and the wall conductance of a heavy wall copper tube reveals that major resistance is on the coolant side. Therefore, there exists a significant opportunity to improve heat transfer in the tubes by enhancement of the coolant side. To this end a variety of copper wool filled tubes as well as a commercially available enhanced copper tube were subjected to laboratory tests with water and conventional heating to assess the resulting heat transfer improvement. Design improvements using enhanced cooling are discussed in terms of structural weight, controls, grazing angles, the operational reliability. 9 refs., 11 figs., 5 tabs.

  14. Computer cooling using a two phase minichannel thermosyphon loop heated from horizontal and vertical sides and cooled from vertical side

    Science.gov (United States)

    Bieliński, Henryk; Mikielewicz, Jarosław

    2010-10-01

    In the present paper it is proposed to consider the computer cooling capacity using the thermosyphon loop. A closed thermosyphon loop consists of combined two heaters and a cooler connected to each other by tubes. The first heater may be a CPU processor located on the motherboard of the personal computer. The second heater may be a chip of a graphic card placed perpendicular to the motherboard of personal computer. The cooler can be placed above the heaters on the computer chassis. The thermosyphon cooling system on the use of computer can be modeled using the rectangular thermosyphon loop with minichannels heated at the bottom horizontal side and the bottom vertical side and cooled at the upper vertical side. The riser and a downcomer connect these parts. A one-dimensional model of two-phase flow and heat transfer in a closed thermosyphon loop is based on mass, momentum, and energy balances in the evaporators, rising tube, condenser and the falling tube. The separate two-phase flow model is used in calculations. A numerical investigation for the analysis of the mass flux rate and heat transfer coefficient in the steady state has been accomplished.

  15. Introduction to solar heating and cooling design and sizing

    Energy Technology Data Exchange (ETDEWEB)

    1978-08-01

    This manual is designed to introduce the practical aspects of solar heating/cooling systems to HVAC contractors, architects, engineers, and other interested individuals. It is intended to enable readers to assess potential solar heating/cooling applications in specific geographical areas, and includes tools necessary to do a preliminary design of the system and to analyze its economic benefits. The following are included: the case for solar energy; solar radiation and weather; passive solar design; system characteristics and selection; component performance criteria; determining solar system thermal performance and economic feasibility; requirements, availability, and applications of solar heating systems; and sources of additional information. (MHR)

  16. Heat Transfer Enhancement for Finned-Tube Heat Exchangers with Vortex Generators: Experimental and Numerical Results

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, James Edward; Sohal, Manohar Singh; Huff, George Albert

    2002-08-01

    A combined experimental and numerical investigation is under way to investigate heat transfer enhancement techniques that may be applicable to large-scale air-cooled condensers such as those used in geothermal power applications. The research is focused on whether air-side heat transfer can be improved through the use of finsurface vortex generators (winglets,) while maintaining low heat exchanger pressure drop. A transient heat transfer visualization and measurement technique has been employed in order to obtain detailed distributions of local heat transfer coefficients on model fin surfaces. Pressure drop measurements have also been acquired in a separate multiple-tube row apparatus. In addition, numerical modeling techniques have been developed to allow prediction of local and average heat transfer for these low-Reynolds-number flows with and without winglets. Representative experimental and numerical results presented in this paper reveal quantitative details of local fin-surface heat transfer in the vicinity of a circular tube with a single delta winglet pair downstream of the cylinder. The winglets were triangular (delta) with a 1:2 height/length aspect ratio and a height equal to 90% of the channel height. Overall mean fin-surface Nusselt-number results indicate a significant level of heat transfer enhancement (average enhancement ratio 35%) associated with the deployment of the winglets with oval tubes. Pressure drop measurements have also been obtained for a variety of tube and winglet configurations using a single-channel flow apparatus that includes four tube rows in a staggered array. Comparisons of heat transfer and pressure drop results for the elliptical tube versus a circular tube with and without winglets are provided. Heat transfer and pressure-drop results have been obtained for flow Reynolds numbers based on channel height and mean flow velocity ranging from 700 to 6500.

  17. Experimental study on rack cooling system based on a pulsating heat pipe

    Science.gov (United States)

    Lu, Qianyi; Jia, Li

    2016-02-01

    A rack cooling system based on a large scale flat plate pulsating heat pipe is proposed. The heat generated from IT equipment in a closed rack is transferred by the rear door pulsating heat pipe to the chilled air passage and is avoided to release into the room. The influence of the start-up performance of the heat pipe, the load of the rack and the load dissipation to the temperature and the velocity distribution in the rack are discussed. It is found that the temperature would be lower and the temperature distribution would be more uniform in the rack when the pulsating heat pipe is in operation. Also, the effect of rack electricity load on temperature distribution is analyzed. It is indicated that higher velocity of chilled air will improve heat transfer of the rack.

  18. Direct electronic measurement of Peltier cooling and heating in graphene

    Science.gov (United States)

    Vera-Marun, I. J.; van den Berg, J. J.; Dejene, F. K.; van Wees, B. J.

    2016-05-01

    Thermoelectric effects allow the generation of electrical power from waste heat and the electrical control of cooling and heating. Remarkably, these effects are also highly sensitive to the asymmetry in the density of states around the Fermi energy and can therefore be exploited as probes of distortions in the electronic structure at the nanoscale. Here we consider two-dimensional graphene as an excellent nanoscale carbon material for exploring the interaction between electronic and thermal transport phenomena, by presenting a direct and quantitative measurement of the Peltier component to electronic cooling and heating in graphene. Thanks to an architecture including nanoscale thermometers, we detected Peltier component modulation of up to 15 mK for currents of 20 μA at room temperature and observed a full reversal between Peltier cooling and heating for electron and hole regimes. This fundamental thermodynamic property is a complementary tool for the study of nanoscale thermoelectric transport in two-dimensional materials.

  19. Heating and cooling of magnetars with accreted envelopes

    CERN Document Server

    Kaminker, A D; Yakovlev, D G; Chabrier, G

    2009-01-01

    We study the thermal structure and evolution of magnetars as cooling neutron stars with a phenomenological heat source in an internal layer. We focus on the effect of magnetized (B > 10^{14} G) non-accreted and accreted outermost envelopes composed of different elements, from iron to hydrogen or helium. We discuss a combined effect of thermal conduction and neutrino emission in the outer neutron star crust and calculate the cooling of magnetars with a dipole magnetic field for various locations of the heat layer, heat rates and magnetic field strengths. Combined effects of strong magnetic fields and light-element composition simplify the interpretation of magnetars in our model: these effects allow one to interpret observations assuming less extreme (therefore, more realistic) heating. Massive magnetars, with fast neutrino cooling in their cores, can have higher thermal surface luminosity.

  20. SENSITIVITY AND DESIGN OF A TRANSCRITICAL CO2 COOLING AND HEATING SYSTEM

    DEFF Research Database (Denmark)

    Nguyen, Chan; Veje, Christian; Willatzen, Morten

    2012-01-01

    uncertainties have on the design results: thermodynamic performance expressed by coefficient of performance (COP) and heat exchanger sizes expressed by weight. The parameters to be investigated are the compressor isentropic efficiency, effectiveness of the internal heat exchanger and pressure drops in the heat...... coupled intended for district cooling and heating respectively. Initially a thermodynamic cycle analysis has been done on the system followed by a heat transfer analysis of the heat exchangers using finite difference models. The main subject of this paper is an investigation of the effects that parameter...... exchangers. The results show that COP is particular sensitive to the pinch temperature in the gas cooler and to the compressor isentropic efficiency but not to pressure loss. However it is found that the heat exchanger weights are very sensitive to pressure loss. The thermodynamic and heat exchanger models...