Effects of heat input on mechanical properties of metal inert gas welded 1.6 mm thick galvanized steel sheet

International Nuclear Information System (INIS)

Rafiqul, M I; Ishak, M; Rahman, M M

2012-01-01

It is usually a lot easier and less expensive to galvanize steel before it is welded into useful products. Galvanizing afterwards is almost impossible. In this research work, Galvanized Steel was welded by using the ER 308L stainless steel filler material. This work was done to find out an alternative way of welding and investigate the effects of heat input on the mechanical properties of butt welded joints of Galvanized Steel. A 13.7 kW maximum capacity MIG welding machine was used to join 1.6 mm thick sheet of galvanized steel with V groove and no gap between mm. Heat inputs was gradually increased from 21.06 to 25.07 joules/mm in this study. The result shows almost macro defects free welding and with increasing heat input the ultimate tensile strength and welding efficiency decrease. The Vickers hardness also decreases at HAZ with increasing heat input and for each individual specimen; hardness was lowest in heat affected zone (HAZ), intermediate in base metal and maximum in welded zone. The fracture for all specimens was in the heat affected zone while testing in the universal testing machine.

Effects of heat input on mechanical properties of metal inert gas welded 1.6 mm thick galvanized steel sheet

Science.gov (United States)

Rafiqul, M. I.; Ishak, M.; Rahman, M. M.

2012-09-01

It is usually a lot easier and less expensive to galvanize steel before it is welded into useful products. Galvanizing afterwards is almost impossible. In this research work, Galvanized Steel was welded by using the ER 308L stainless steel filler material. This work was done to find out an alternative way of welding and investigate the effects of heat input on the mechanical properties of butt welded joints of Galvanized Steel. A 13.7 kW maximum capacity MIG welding machine was used to join 1.6 mm thick sheet of galvanized steel with V groove and no gap between mm. Heat inputs was gradually increased from 21.06 to 25.07 joules/mm in this study. The result shows almost macro defects free welding and with increasing heat input the ultimate tensile strength and welding efficiency decrease. The Vickers hardness also decreases at HAZ with increasing heat input and for each individual specimen; hardness was lowest in heat affected zone (HAZ), intermediate in base metal and maximum in welded zone. The fracture for all specimens was in the heat affected zone while testing in the universal testing machine.

Effect of variable heat input on the heat transfer characteristics in an Organic Rankine Cycle system

Directory of Open Access Journals (Sweden)

Aboaltabooq Mahdi Hatf Kadhum

2016-01-01

Full Text Available This paper analyzes the heat transfer characteristics of an ORC evaporator applied on a diesel engine using measured data from experimental work such as flue gas mass flow rate and flue gas temperature. A mathematical model was developed with regard to the preheater, boiler and the superheater zones of a counter flow evaporator. Each of these zones has been subdivided into a number of cells. The hot source of the ORC cycle was modeled. The study involves the variable heat input's dependence on the ORC system's heat transfer characteristics, with especial emphasis on the evaporator. The results show that the refrigerant's heat transfer coefficient has a higher value for a 100% load from the diesel engine, and decreases with the load decrease. Also, on the exhaust gas side, the heat transfer coefficient decreases with the decrease of the load. The refrigerant's heat transfer coefficient increased normally with the evaporator's tube length in the preheater zone, and then increases rapidly in the boiler zone, followed by a decrease in the superheater zone. The exhaust gases’ heat transfer coefficient increased with the evaporator’ tube length in all zones. The results were compared with result by other authors and were found to be in agreement.

Microstructure and mechanical properties of hard zone in friction stir welded X80 pipeline steel relative to different heat input

Energy Technology Data Exchange (ETDEWEB)

Aydin, Hakan, E-mail: hakanay@uludag.edu.tr [Engineering and Architecture Faculty, Mechanical Engineering Department, Uludag University, 16059 Gorukle-Bursa (Turkey); Nelson, Tracy W. [Mechanical Engineering Department, Brigham Young University, 435 CTB, Provo, UT 84602 (United States)

2013-12-01

The study was conducted to investigate the microstructure and mechanical properties of the hard zone in friction stir welded X80 pipeline steel at different heat inputs. Microstructural analysis of the welds was carried out using optical microscopy, transmission electron microscopy, and microhardness. Heat input during friction stir welding process had a significant influence on the microstructure and mechanical properties in the hard zone along the advancing side of the weld nugget. Based on the results, the linear relationships between heat input and post-weld microstructures and mechanical properties in the hard zone of friction stir welded X80 steels were established. It can be concluded that with decrease in heat input the bainitic structure in the hard zone becomes finer and so hard zone strength increases.

Microstructure and mechanical properties of hard zone in friction stir welded X80 pipeline steel relative to different heat input

International Nuclear Information System (INIS)

Aydin, Hakan; Nelson, Tracy W.

2013-01-01

The study was conducted to investigate the microstructure and mechanical properties of the hard zone in friction stir welded X80 pipeline steel at different heat inputs. Microstructural analysis of the welds was carried out using optical microscopy, transmission electron microscopy, and microhardness. Heat input during friction stir welding process had a significant influence on the microstructure and mechanical properties in the hard zone along the advancing side of the weld nugget. Based on the results, the linear relationships between heat input and post-weld microstructures and mechanical properties in the hard zone of friction stir welded X80 steels were established. It can be concluded that with decrease in heat input the bainitic structure in the hard zone becomes finer and so hard zone strength increases

Effects of Heat Input on the Mechanical and Metallurgical Characteristics of Tig Welded Incoloy 800Ht Joints

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Kumar S. Arun

2017-09-01

Full Text Available This study focuses on the effect of heat input on the quality characteristics of tungsten inert arc gas welded incoloy 800HT joints using inconel-82 filler wire. Butt welding was done on specimens with four different heat inputs by varying the process parameters like welding current and speed. The result indicated that higher heat input levels has led to the formation of coarser grain structure, reduced mechanical properties and sensitization issues on the weldments. The formation of titanium nitrides provided resistance to fracture and increased the tensile strength of the joints at high temperatures. Further aging was done on the welded sample at a temperature of 750°C for 500 hours and the metallographic result showed formation of carbides along the grain boundaries in a chain of discrete and globular form which increased the hardness of the material. The formation of spinel NiCr2O4 provided oxidation resistance to the material during elevated temperature service.

Effects of heat input on the pitting resistance of Inconel 625 welds by overlay welding

Science.gov (United States)

Kim, Jun Seok; Park, Young IL; Lee, Hae Woo

2015-03-01

The objective of this study was to establish the relationship between the dilution ratio of the weld zone and pitting resistance depending on the heat input to welding of the Inconel alloy. Each specimen was produced by electroslag welding using Inconel 625 as the filler metal. In the weld zone of each specimen, dendrite grains were observed near the fusion line and equiaxed grains were observed on the surface. It was also observed that a melted zone with a high Fe content was formed around the fusion line, which became wider as the welding heat input increased. In order to evaluate the pitting resistance, potentiodynamic polarization tests and CPT tests were conducted. The results of these tests confirmed that there is no difference between the pitting resistances of each specimen, as the structures of the surfaces were identical despite the effect of the differences in the welding heat input for each specimen and the minor dilution effect on the surface.

Effect of Welding Heat Input on Microstructure and Texture of Inconel 625 Weld Overlay Studied Using the Electron Backscatter Diffraction Method

Science.gov (United States)

Kim, Joon-Suk; Lee, Hae-Woo

2016-12-01

The grain size and the texture of three specimens prepared at different heat inputs were determined using optical microscopy and the electron backscatter diffraction method of scanning electron microscopy. Each specimen was equally divided into fusion line zone (FLZ), columnar dendrite zone (CDZ), and surface zone (SZ), according to the location of the weld. Fine dendrites were observed in the FLZ, coarse dendrites in the CDZ, and dendrites grew perpendicular to the FLZ and CDZ. As the heat input increased, the melted zone in the vicinity of the FLZ widened due to the higher Fe content. A lower image quality value was observed for the FLZ compared to the other zones. The results of grain size measurement in each zone showed that the grain size of the SZ became larger as the heat input increased. From the inverse pole figure (IPF) map in the normal direction (ND) and the rolling direction (RD), as the heat input increased, a specific orientation was formed. However, a dominant [001] direction was observed in the RD IPF map.

Effect of heat input on microstructure and mechanical properties of dissimilar joints between super duplex stainless steel and high strength low alloy steel

International Nuclear Information System (INIS)

Sadeghian, M.; Shamanian, M.; Shafyei, A.

2014-01-01

Highlights: • The microstructure of weld metal consists of austenite and ferrite. • The HAZ of the API X-65 shows different transformation. • Impact strength of sample with low heat input was lower than base metals. • The heat input at 0.506 kJ/mm is not the suitable for dissimilar joining between UNS S32750/API X-65. - Abstract: In the present study, microstructure and mechanical properties of UNS S32750 super duplex stainless steel (SDSS)/API X-65 high strength low alloy steel (HSLA) dissimilar joint were investigated. For this purpose, gas tungsten arc welding (GTAW) was used in two different heat inputs: 0.506 and 0.86 kJ/mm. The microstructures investigation with optical microscope, scanning electron microscope and X-ray diffraction showed that an increase in heat input led to a decrease in ferrite percentage, and that detrimental phases were not present. It also indicated that in heat affected zone of HSLA base metal in low heat input, bainite and ferrite phases were created; but in high heat input, perlite and ferrite phases were created. The results of impact tests revealed that the specimen with low heat input exhibited brittle fracture and that with high heat input had a higher strength than the base metals

Development of High Heat Input Welding Offshore Steel as Normalized Condition

Science.gov (United States)

Deng, Wei; Qin, Xiaomei

The heavy plate used for offshore structure is one of the important strategic products. In recent years, there is an increasing demand for heavy shipbuilding steel plate with excellent weldability in high heat input welding. During the thermal cycle, the microstructure of the heat affected zone (HAZ) of plates was damaged, and this markedly reduced toughness of HAZ. So, how to improve the toughness of HAZ has been a key subject in the fields of steel research. Oxide metallurgy is considered as an effective way to improve toughness of HAZ, because it could be used to retard grain growth by fine particles, which are stable at the high temperature.The high strength steel plate, which satisfies the low temperature specification, has been applied to offshore structure. Excellent properties of the plates and welded joints were obtained by oxide metallurgy technology, latest controlled rolling and accelerated cooling technology using Ultra-Fast Cooling (an on-line accelerated cooling system). The 355MPa-grade high strength steel plates with normalizing condition were obtained, and the steels have excellent weldability with heat input energy of 79 287kJ/cm, and the nil ductility transition (NDT) temperature was -70°C, which can satisfy the construction of offshore structure in cold regions.

Heat input properties of hollow cathode arc as a welding heat source

International Nuclear Information System (INIS)

Nishikawa, Hiroshi; Shobako, Shinichiro; Ohta, Masashi; Ohji, Takayoshi

2005-01-01

In order to clarify whether a hollow cathode arc (HCA) can be used as a welding heat source in space, investigations into the fundamental characteristics of HCA were experimentally performed under low pressure conditions. The HCA method enables an arc discharge to ignite and maintain under low pressure conditions; in contrast, low pressure conditions make it extremely difficult for the conventional gas tungsten arc method to form an arc discharge. In an earlier paper, it was shown that the melting process by HCA is very sensitive to process parameters such as the gas flow rate and arc length, and a deep penetration forms when the arc length is long and the gas flow rate is low. In this paper, the distribution of the arc current on the anode surface and the plasma properties of the HCA under low pressure conditions have been made clear and the total heat energy to the anode has been discussed in order to understand the heat input properties of the HCA. The result shows that the HCA in the case of a low gas flow rate is a high and concentrated energy source, and the high energy input to the anode contributes to the deep penetration

Influence of heat input and radius to pipe thickness ratio on the residual stresses in circumferential arc welded pipes of API X46 steels

International Nuclear Information System (INIS)

Hemmatzadeh, Majid; Moshayedi, Hessamoddin; Sattari-Far, Iradj

2017-01-01

The present work aims to study residual stresses caused by circumferentially welding of two similar API X46 steel pipes by means of finite element modeling. Considering the metallurgical phase transformations and through thermal-mechanical uncoupled analysis, the 3D modeling was carried out by SYSWELD software. Materialistic thermal and mechanical properties of all phases were defined in terms of temperature as well as phase transformation properties. Residual stress was measured through hole-drilling method. The obtained results were used to verify the finite element model. By means of full factorial experiment designing method, effects of heat input and radius to pipe thickness ratio on maximum values of hoop and axial residual stresses were investigated. The effect of each factor was studied in 3 levels and by 9 experiments. Results of statistical analysis revealed that increase in heat input and radius-thickness ratio would lead to higher values of maximum hoop and axial residual stresses. However, interactions of high level of heat input and a low level of radius-thickness ratio increased inter-pass temperature and consequently caused a sudden raise in maximum values of residual stresses. - Highlights: • A FEM model was developed to simulate welding considering phase transformations. • The obtained residual stresses were validated by experiments. • Effect of heat input and radius-to-thickness ratio on residual stress were investigated. • Increasing heat input for 100% caused increasing hoop and axial residual stress until 200%. • Interaction of high heat input and low R/t causes a sudden increase in axial residual stresses.

Total dose induced increase in input offset voltage in JFET input operational amplifiers

International Nuclear Information System (INIS)

Pease, R.L.; Krieg, J.; Gehlhausen, M.; Black, J.

1999-01-01

Four different types of commercial JFET input operational amplifiers were irradiated with ionizing radiation under a variety of test conditions. All experienced significant increases in input offset voltage (Vos). Microprobe measurement of the electrical characteristics of the de-coupled input JFETs demonstrates that the increase in Vos is a result of the mismatch of the degraded JFETs. (authors)

Influence of heat input in electron beam process on microstructure and properties of duplex stainless steel welded interface

Science.gov (United States)

Zhang, Zhiqiang; Jing, Hongyang; Xu, Lianyong; Han, Yongdian; Zhao, Lei; Lv, Xiaoqing; Zhang, Jianyang

2018-03-01

The influence of heat input in electron beam (EB) process on microstructure, mechanical properties, and pitting corrosion resistance of duplex stainless steel (DSS) welded interface was investigated. The rapid cooling in EB welding resulted in insufficient austenite formation. The austenite mainly consisted of grain boundary austenite and intragranular austenite, and there was abundant Cr2N precipitation in the ferrite. The Ni, Mo, and Si segregation indicated that the dendritic solidification was primarily ferrite in the weld. The weld exhibited higher hardness, lower toughness, and poorer pitting corrosion resistance than the base metal. The impact fractures of the welds were dominated by the transgranular cleavage failure of the ferrite. The ferrite was selectively attacked because of its lower pitting resistance equivalent number than that of austenite. The Cr2N precipitation accelerated the pitting corrosion. In summary, the optimised heat input slightly increased the austenite content, reduced the segregation degree and ferrite texture intensity, decreased the hardness, and improved the toughness and pitting corrosion resistance. However, the effects were limited. Furthermore, optimising the heat input could not suppress the Cr2N precipitation. Taking into full consideration the microstructure and properties, a heat input of 0.46 kJ/mm is recommended for the EB welding of DSS.

Effect of finite heat input on the power performance of micro heat engines

International Nuclear Information System (INIS)

Khu, Kerwin; Jiang, Liudi; Markvart, Tom

2011-01-01

Micro heat engines have attracted considerable interest in recent years for their potential exploitation as micro power sources in microsystems and portable devices. Thermodynamic modeling can predict the theoretical performance that can be potentially achieved by micro heat engine designs. An appropriate model can not only provide key information at the design stage but also indicate the potential room for improvement in existing micro heat engines. However, there are few models reported to date which are suitable for evaluating the power performance of micro heat engines. This paper presents a new thermodynamic model for determining the theoretical limit of power performance of micro heat engines with consideration to finite heat input and heat leakage. By matching the model components to those of a representative heat engine layout, the theoretical power, power density, and thermal efficiency achievable for a micro heat engine can be obtained for a given set of design parameters. The effects of key design parameters such as length and thermal conductivity of the engine material on these theoretical outputs are also investigated. Possible trade-offs among these performance objectives are discussed. Performance results derived from the developed model are compared with those of a working micro heat engine (P3) as an example. -- Highlights: → Thermodynamic model for micro heat engines. → Effect of different parameters on potential performance. → Tradeoffs for determining optimal size of micro engines.

Effects of Heat Input on Microstructure, Corrosion and Mechanical Characteristics of Welded Austenitic and Duplex Stainless Steels: A Review

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Ghusoon Ridha Mohammed

2017-01-01

Full Text Available The effects of input heat of different welding processes on the microstructure, corrosion, and mechanical characteristics of welded duplex stainless steel (DSS are reviewed. Austenitic stainless steel (ASS is welded using low-heat inputs. However, owing to differences in the physical metallurgy between ASS and DSS, low-heat inputs should be avoided for DSS. This review highlights the differences in solidification mode and transformation characteristics between ASS and DSS with regard to the heat input in welding processes. Specifically, many studies about the effects of heat energy input in welding process on the pitting corrosion, intergranular stress, stresscorrosion cracking, and mechanical properties of weldments of DSS are reviewed.

Effects of Heat Input and Bead Generation Methods on Finite Element Analysis of Multi-Pass Welding Process

Energy Technology Data Exchange (ETDEWEB)

Park, Won Dong; Kim, Ji Hoon; Bahn, Chi Bum [Pusan National University, Busan (Korea, Republic of)

2016-10-15

Welding residual stresses are determined by various factors such as heat input, initial temperature of molten bead, heating time, cooling time, cooling conditions, and boundary conditions. In this study, a sensitivity analysis was performed to find the major factors and reasonable assumptions for simulation. Two-dimensional axisymmetric simulation was conducted by using commercial finite element analysis program ABAQUS, for multi-pass Alloy 82 welds in a 304 Stainless Steel and SA-105 Carbon Steel. The major object is to evaluate effects of the heat input methods and weld bead generation methods on the welding residual stress distribution. Totally four kinds of methods were compared. From the previous results, we could make the following conclusions. 1. Although there are non-negligible differences in HAZ depending on heat input method, welding residual stress distributions have roughly similar trends. However, it is needed to perform the more exact analysis to apply heat energy more carefully into the individual bead. 2. Residual stress distribution were similar for the two weld bead generation technique. However, overlapping was happened when element birth technique was applied. Effects of overlapping could not ignore as deformation increases. However, overlapping problem was avoided when quiet element technique was used. 3. Since existence of inactive bead elements, inaccurate weld residual stresses could be occurred in boundaries of previous and next weld elements in case of quiet element technique.

Corrosion behavior in high heat input welded heat-affected zone of Ni-free high-nitrogen Fe–18Cr–10Mn–N austenitic stainless steel

International Nuclear Information System (INIS)

Moon, Joonoh; Ha, Heon-Young; Lee, Tae-Ho

2013-01-01

The pitting corrosion and interphase corrosion behaviors in high heat input welded heat-affected zone (HAZ) of a metastable high-nitrogen Fe–18Cr–10Mn–N austenitic stainless steel were explored through electrochemical tests. The HAZs were simulated using Gleeble simulator with high heat input welding condition of 300 kJ/cm and the peak temperature of the HAZs was changed from 1200 °C to 1350 °C, aiming to examine the effect of δ-ferrite formation on corrosion behavior. The electrochemical test results show that both pitting corrosion resistance and interphase corrosion resistance were seriously deteriorated by δ-ferrite formation in the HAZ and their aspects were different with increasing δ-ferrite fraction. The pitting corrosion resistance was decreased by the formation of Cr-depleted zone along δ-ferrite/austenite (γ) interphase resulting from δ-ferrite formation; however it didn't depend on δ-ferrite fraction. The interphase corrosion resistance depends on the total amount of Cr-depleted zone as well as ferrite area and thus continuously decreased with increasing δ-ferrite fraction. The different effects of δ-ferrite fraction on pitting corrosion and interphase corrosion were carefully discussed in terms of alloying elements partitioning in the HAZ based on thermodynamic consideration. - Highlights: • Corrosion behavior in the weld HAZ of high-nitrogen austenitic alloy was studied. • Cr 2 N particle was not precipitated in high heat input welded HAZ of tested alloy. • Pitting corrosion and interphase corrosion show a different behavior. • Pitting corrosion resistance was affected by whether or not δ-ferrite forms. • Interphase corrosion resistance was affected by the total amount of δ-ferrite

Increasing inhibitory input increases neuronal firing rate: why and when? Diffusion process cases

Energy Technology Data Exchange (ETDEWEB)

Feng Jianfeng [COGS, Sussex University (United Kingdom)]. E-mail: jf218@cam.ac.uk; Wei Gang [Department of Mathematics, Hong Kong Baptist University, Hong Kong (China)]. E-mail gwei@math.hkbu.edu.hk

2001-09-21

Increasing inhibitory input to single neuronal models, such as the FitzHugh-Nagumo model and the Hodgkin-Huxley model, can sometimes increase their firing rates, a phenomenon which we term inhibition-boosted firing (IBF). Here we consider neuronal models with diffusion approximation inputs, i.e. they share the identical first- and second-order statistics of the corresponding Poisson process inputs. Using the integrate-and-fire model and the IF-FHN model, we explore theoretically how and when IBF can happen. For both models, it is shown that there is a critical input frequency at which the efferent firing rate is identical when the neuron receives purely excitatory inputs or exactly balanced inhibitory and excitatory inputs. When the input frequency is lower than the critical frequency, IBF occurs. (author)

Optimum systems design with random input and output applied to solar water heating

Science.gov (United States)

Abdel-Malek, L. L.

1980-03-01

Solar water heating systems are evaluated. Models were developed to estimate the percentage of energy supplied from the Sun to a household. Since solar water heating systems have random input and output queueing theory, birth and death processes were the major tools in developing the models of evaluation. Microeconomics methods help in determining the optimum size of the solar water heating system design parameters, i.e., the water tank volume and the collector area.

A study on influence of heat input variation on microstructure of reduced activation ferritic martensitic steel weld metal produced by GTAW process

International Nuclear Information System (INIS)

Arivazhagan, B.; Srinivasan, G.; Albert, S.K.; Bhaduri, A.K.

2011-01-01

Reduced activation ferritic martensitic (RAFM) steel is a major structural material for test blanket module (TBM) to be incorporated in International Thermonuclear Experimental Reactor (ITER) programme to study the breeding of tritium in fusion reactors. This material has been mainly developed to achieve significant reduction in the induced radioactivity from the structural material used. Fabrication of TBM involves extensive welding, and gas tungsten arc welding (GTAW) process is one of the welding processes being considered for this purpose. In the present work, the effect of heat input on microstructure of indigenously developed RAFM steel weld metal produced by GTAW process has been studied. Autogenous bead-on-plate welding, autogenous butt-welding, butt-welding with filler wire addition, and pulsed welding on RAFMS have been carried out using GTAW process respectively. The weld metal is found to contain δ-ferrite and its volume fraction increased with increase in heat input. This fact suggests that δ-ferrite content in the weld metal is influenced by the cooling rate during welding. It was also observed that the hardness of the weld metal decreased with increase in δ-ferrite content. This paper highlights the effect of heat input and PWHT duration on microstructure and hardness of welds.

Heat input effect of friction stir welding on aluminium alloy AA 6061-T6 welded joint

Directory of Open Access Journals (Sweden)

Sedmak Aleksandar

2016-01-01

Full Text Available This paper deals with the heat input and maximum temperature developed during friction stir welding with different parameters. Aluminium alloy (AA 6061-T6 has been used for experimental and numerical analysis. Experimental analysis is based on temperature measurements by using infrared camera, whereas numerical analysis was based on empirical expressions and finite element method. Different types of defects have been observed in respect to different levels of heat input.

Evaluation of the Low Heat Input Process for Weld Repair of Nickel-Base Superalloys

Science.gov (United States)

Durocher, J.; Richards, N. L.

2011-10-01

The repair of turbine blades and vanes commonly involves gas tungsten arc welding or an equivalent process, but unfortunately these components are often susceptible to heat-affected zone (HAZ) cracking during the weld repair process. This is a major problem especially in cast alloys due to their coarse-grain size and where the (Al + Ti) contents is in excess of 3-4%; vacuum brazing is also used but mainly on low stress non-rotating components such as vanes. Micro-welding has the potential to deposit small amounts of filler at low heat input levels with minimum HAZ and thus is an attractive process for depositing a quality weld. As with conventional fusion processes, the filler alloy is deposited by the generation of a low power arc between a consumable electrode and the substrate. The low heat input of this process offers unique advantages over more common welding processes such as gas tungsten arc, plasma arc, laser, and electron beam welding. In this study, the low heat input characteristic of micro-welding has been used to simulate weld repair using Inconel (IN) (Inconel and IN are trademarks of INCO Alloys International) 625, Rene (Rene is a trademark of General Electric Company) 41, Nimonic (Nimonic is a trademark of INCO Alloys International) 105 and Inconel 738LC filler alloys, to a cast Inconel 738LC substrate. The effect of micro-welding process parameters on the deposition rate, coating quality, and substrate has been investigated.

The influence of high heat input and inclusions control for rare earth on welding in low alloy high strength steel

Science.gov (United States)

Chu, Rensheng; Mu, Shukun; Liu, Jingang; Li, Zhanjun

2017-09-01

In the current paper, it is analyzed for the influence of high heat input and inclusions control for rare earth on welding in low alloy high strength steel. It is observed for the structure for different heat input of the coarse-grained area. It is finest for the coarse grain with the high heat input of 200 kJ / cm and the coarse grain area with 400 kJ / cm is the largest. The performance with the heat input of 200 kJ / cm for -20 °C V-shaped notch oscillatory power is better than the heat input of 400 kJ / cm. The grain structure is the ferrite and bainite for different holding time. The grain structure for 5s holding time has a grain size of 82.9 μm with heat input of 200 kJ/cm and grain size of 97.9 μm for 10s holding time. For the inclusions for HSLA steel with adding rare earth, they are Al2O3-CaS inclusions in the Al2O3-CaS-CaO ternary phase diagram. At the same time, it can not be found for low melting calcium aluminate inclusions compared to the inclusions for the HSLA steel without rare earth. Most of the size for the inclusions is between 1 ~ 10μm. The overall grain structure is smaller and the welding performance is more excellent for adding rare earth.

Response of Cryolite-Based Bath to a Shift in Heat Input/output Balance

Science.gov (United States)

Liu, Jingjing; Taylor, Mark; Dorreen, Mark

2017-04-01

A technology for low amperage potline operation is now recognized as a competitive advantage for the aluminum smelting industry in order to align smelter operations with the power and aluminum price markets. This study investigates the cryolite-based bath response to heat balance shifts when the heat extraction from the bath is adjusted to different levels in a laboratory analogue. In the analogue experiments, the heat balance shift is driven by a graphite `cold finger' heat exchanger, which can control the heat extraction from the analogue, and a corresponding change in heat input from the furnace which maintains the control temperature of the lab "cell." This paper reports the first experimental results from shifting the steady state of the lab cell heat balance, and investigates the effects on the frozen ledge and bath superheat. The lab cell energy balances are compared with energy balances in a published industrial cell model.

Thermal insulation of high confinement mode with dominant electron heating in comparison to dominant ion heating and corresponding changes of torque input

International Nuclear Information System (INIS)

Sommer, Fabian H.D.

2013-01-01

The ratio of heating power going to electrons and ions will undergo a transition from mixed electron and ion heating as it is in current fusion experiments to dominant electron heating in future experiments and reactors. In order to make valid projections towards future devices the connected changes in plasma response and performance are important to be study and understand: Do electron heated plasmas behave systematically different or is the change of heated species fully compensated by heat exchange from electrons to ions? How does particle transport influence the density profile? Is the energy confinement and the H-mode pedestal reduced with reduced torque input? Does the turbulent transport regime change fundamentally? The unique capabilities of the ECRH system at ASDEX Upgrade enable this change of heated species by replacing NBI with ECRH power and thereby offer the possibility to discuss these and other questions. For low heating powers corresponding to high collisionalities the transition from mixed electron and ion heating to pure electron heating showed next to no degradation of the global plasma parameters and no change of the edge values of kinetic profiles. The electron density shows an increased central peaking with increased ECRH power. The central electron temperature stays constant while the ion temperature decreases slightly. The toroidal rotation decreases with reduced NBI fraction, but does not influence the profile stability. The power balance analysis shows a large energy transfer from electrons to ions, so that the electron heat flux approaches zero at the edge whereas the ion heat flux is independent of heating mix. The ion heat diffusivity exceeds the electron one. For high power, low collisionality discharges global plasma parameters show a slight degradation with increasing electron heating. The density profile shows a strong peaking which remains unchanged when modifying the heating mix. The electron temperature profile is unchanged

Development and testing of aluminum micro channel heat sink

Science.gov (United States)

Kumaraguruparan, G.; Sornakumar, T.

2010-06-01

Microchannel heat sinks constitute an innovative cooling technology for the removal of a large amount of heat from a small area and are suitable for electronics cooling. In the present work, Tool Steel D2 grade milling slitting saw type plain milling cutter is fabricated The microchannels are machined in aluminum work pieces to form the microchannel heat sink using the fabricated milling cutter in an horizontal milling machine. A new experimental set-up is fabricated to conduct the tests on the microchannel heat sink. The heat carried by the water increases with mass flow rate and heat input. The heat transfer coefficient and Nusselt number increases with mass flow rate and increased heat input. The pressure drop increases with Reynolds number and decreases with input heat. The friction factor decreases with Reynolds number and decreases with input heat. The thermal resistance decreases with pumping power and decreases with input heat.

Effect of heat-insulating wall on input energy of a photovoltaic/solar/air-heat system for a residence; Jutaku no kodannetsuka ni yoru taiyoko netsu/taiki netsu system no donyu energy sakugen koka

Energy Technology Data Exchange (ETDEWEB)

Kenmoku, Y; Sakakibara, T [Toyohashi University of Technology, Aichi (Japan); Nakagawa, S [Maizuru College of Technology, Kyoto (Japan)

1996-10-27

A proposal was made to introduce a photovoltaic/solar/air-heat system which positively utilizes natural energy in order to curtail consumption of fossil energy, corroborating that the system has greatly reduced energy input in the primary energy level in a house. This paper examines the effect of curtailment of energy input in the case of reducing the load of air conditioning through the high heat insulation of a house. The energy input was evaluated by calculating additional equipment energy needed newly for the high heat insulation. The system performance and the energy load varied greatly depending on weather conditions. The subject system consisted of solar cells, inverter, heat concentrator, heat storage tank, heat pump and gas hot-water supply device. The thickening of the insulation sharply reduced heating load in the house, thereby decreasing fuel energy substantially. An insulation material of 100mm thick was capable of reducing energy input by 16-23% compared with that of 50mm thick. 5 refs., 5 figs, 3 tabs.

Effects of the Back Plate Inner Diameter on the Frictional Heat Input and General Performance of Brush Seals

Directory of Open Access Journals (Sweden)

Manuel Hildebrandt

2018-05-01

Full Text Available Reducing losses in the secondary air system of gas and steam turbines can significantly increase the efficiency of such machines. Meanwhile, brush seals are a widely used alternative to labyrinth seals. Their most valuable advantage over other sealing concepts is the very small gap between the sealing package and the rotor and thus reduced leakage mass flow. This small gap can be achieved due to the great radial flexibility without running the risk of severe detrimental deterioration in case of rubbing. Rubbing between rotor and seal during operation might occur as a result of e.g., an unequal thermal expansion of the rotor and stator or a rotor elongation due to centrifugal forces or manoeuvre forces. Thanks to the flexible structure of the brush seal, the contact forces during a rubbing event are reduced; however, the frictional heat input can still be considerable. Particularly in aircraft engines with their thin and lightweight rotor structures, the permissible material stresses can easily be exceeded by an increased heat input and thus harm the engine’s integrity. The geometry of the seal has a decisive influence on the resulting contact forces and consequently the heat input. This paper is a contribution to further understand the influence of the geometrical parameters of the brush seal on the heat input and the leakage during the rubbing of the seal on the rotor. In this paper, a total of three seals with varied back plate inner diameter are examined in more detail. The experimental tests were carried out on the brush seal test rig of the Institute of Thermal Turbomachinery (ITS under machine-relevant conditions. These are represented by pressure differences of 1 to 7 bar, surface speeds of 30 to 180 m/s and radial interferences of 0.1 to 0.4 mm. For a better interpretation, the results were compared with those obtained at the static test rig of the Institute of Jet Propulsion and Turbomachinery (IFAS at the Technical University of

Silicon Carbide (SiC) Device and Module Reliability, Performance of a Loop Heat Pipe Subjected to a Phase-Coupled Heat Input to an Acceleration Field

Science.gov (United States)

2016-05-01

AFRL-RQ-WP-TR-2016-0108 SILICON CARBIDE (SiC) DEVICE AND MODULE RELIABILITY Performance of a Loop Heat Pipe Subjected to a Phase-Coupled...CARBIDE (SiC) DEVICE AND MODULE RELIABILITY Performance of a Loop Heat Pipe Subjected to a Phase-Coupled Heat Input to an Acceleration Field 5a...Shukla, K., “Thermo-fluid dynamics of Loop Heat Pipe Operation,” International Communications in Heat and Mass Transfer , Vol. 35, No. 8, 2008, pp

40 CFR 75.83 - Calculation of Hg mass emissions and heat input rate.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Calculation of Hg mass emissions and... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Hg Mass Emission Provisions § 75.83 Calculation of Hg mass emissions and heat input rate. The owner or operator shall calculate Hg mass emissions...

STUDY OF THE INFLUENCE OF THE HEAT INPUT ON MECHANICAL PROPERTIES OF C-Mn STEEL WELD METALS OBTAINED BY SUBMERGED ARC PROCESS

Directory of Open Access Journals (Sweden)

Erick de Sousa Marouço

2013-06-01

Full Text Available The present work is part of a research program that aims to evaluate the technical feasibility of increasing productivity in the manufacturing of tubular components for offshore oil industry, which are fully welded by automatic submerged arc welding process, with high heat input, but with no impairment on the impact toughness of the weld metal. Multipass welds were produced by the submerged arc welding process, with a combination of F7A4-EM12K (wire/flux, by using a 3.2 mm-diameter wire, preheating at 80°C, with direct current, in flat position, with heat input varying from 3.5 kJ/mm to 12 kJ/mm. After welding, tensile tests and Charpy-V impact tests at –60°C, –40°C, –20°C, 0°C and 20°C were carried out, as well as metallographic examination by both optical (OM and scanning electron microscopy (SEM, of specimens obtained entirely from the weld metal, allowing the discussion over the toughness X microstructure relationship. The weld metals have shown higher toughness levels in relation to the minimum required for use with low-alloy C-Mn steels welding with requirements of impact toughness of 27 J at 0°C for heat input up to 12 kJ/mm allowing an increase in productivity of 58% on the effective manufacturing time.

Effect of heat input on microstructure, wear and friction behavior of (wt.-%) 50FeCrC-20FeW-30FeB coating on AISI 1020 produced by using PTA welding.

Science.gov (United States)

Özel, Cihan; Gürgenç, Turan

2018-01-01

In this study, AISI 1020 steel surface was coated in different heat inputs with (wt.-%) 50FeCrC-20FeW-30FeB powder mixture by using plasma transferred arc (PTA) welding method. The microstructure of the coated samples were investigated by using optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDS). The hardness was measured with micro hardness test device. The dry sliding wear and friction coefficient properties were determined using a block-on-disk type wear test device. Wear tests were performed at 19.62 N, 39.24 N, 58.86 N load and the sliding distance of 900 m. The results were shown that different microstructures formed due to the heat input change. The highest average micro hardness value was measured at 1217 HV on sample coated with low heat input. It was determined that the wear resistance decreased with increasing heat input.

Influence of heat input on weld bead geometry using duplex stainless steel wire electrode on low alloy steel specimens

Directory of Open Access Journals (Sweden)

Ajit Mondal

2016-12-01

Full Text Available Gas metal arc welding cladding becomes a popular surfacing technique in many modern industries as it enhances effectively corrosion resistance property and wear resistance property of structural members. Quality of weld cladding may be enhanced by controlling process parameters. If bead formation is found acceptable, cladding is also expected to be good. Weld bead characteristics are often assessed by bead geometry, and it is mainly influenced by heat input. In this paper, duplex stainless steel E2209 T01 is deposited on E250 low alloy steel specimens with 100% CO2 gas as shielding medium with different heats. Weld bead width, height of reinforcement and depth of penetration are measured. Regression analysis is done on the basis of experimental data. Results reveal that within the range of bead-on-plate welding experiments done, parameters of welding geometry are on the whole linearly related with heat input. A condition corresponding to 0.744 kJ/mm heat input is recommended to be used for weld cladding in practice.

Increase of COP for heat transformer in water purification systems. Part I - Increasing heat source temperature

International Nuclear Information System (INIS)

Siqueiros, J.; Romero, R.J.

2007-01-01

The integration of a water purification system in a heat transformer allows a fraction of heat obtained by the heat transformer to be recycled, increasing the heat source temperature. Consequently, the evaporator and generator temperatures are also increased. For any operating conditions, keeping the condenser and absorber temperatures and also the heat load to the evaporator and generator, a higher value of COP is obtained when only the evaporator and generator temperatures are increased. Simulation with proven software compares the performance of the modeling of an absorption heat transformer for water purification (AHTWP) operating with water/lithium bromide, as the working fluid-absorbent pair. Plots of enthalpy-based coefficients of performance (COP ET ) and the increase in the coefficient of performance (COP) are shown against absorber temperature for several thermodynamic operating conditions. The results showed that proposed (AHTWP) system is capable of increasing the original value of COP ET more than 120%, by recycling part of the energy from a water purification system. The proposed system allows to increase COP values from any experimental data for water purification or any other distillation system integrated to a heat transformer, regardless of the actual COP value and any working fluid-absorbent pair

Magnetospheric energy inputs into the upper atmospheres of the giant planets

Directory of Open Access Journals (Sweden)

C. G. A. Smith

2005-07-01

Full Text Available We revisit the effects of Joule heating upon the upper atmospheres of Jupiter and Saturn. We show that in addition to direct Joule heating there is an additional input of kinetic energy – ion drag energy – which we quantify relative to the Joule heating. We also show that fluctuations about the mean electric field, as observed in the Earth's ionosphere, may significantly increase the Joule heating itself. For physically plausible parameters these effects may increase previous estimates of the upper atmospheric energy input at Saturn from ~10 TW to ~20 TW.

Keywords. Ionosphere (Electric fields and currents; Planetary ionosphere – Magnetospheric physics (Auroral phenomena

In-process tool rotational speed variation with constant heat input in friction stir welding of AZ31 sheets with variable thickness

Science.gov (United States)

Buffa, Gianluca; Campanella, Davide; Forcellese, Archimede; Fratini, Livan; Simoncini, Michela

2017-10-01

In the present work, friction stir welding experiments on AZ31 magnesium alloy sheets, characterized by a variable thickness along the welding line, were carried out. The approach adapted during welding consisted in maintaining constant the heat input to the joint. To this purpose, the rotational speed of the pin tool was increased with decreasing thickness and decreased with increasing thickness in order to obtain the same temperatures during welding. The amount by which the rotational speed was changed as a function of the sheet thickness was defined on the basis of the results given by FEM simulations of the FSW process. Finally, the effect of the in-process variation of the tool rotational speed on the mechanical and microstructural properties of FSWed joints was analysed by comparing both the nominal stress vs. nominal strain curves and microstructure of FSWed joints obtained in different process conditions. It was observed that FSW performed by keeping constant the heat input to the joint leads to almost coincident results both in terms of the curve shape, ultimate tensile strength and ultimate elongation values, and microstructure.

Metallurgy and mechanical properties variation with heat input,during dissimilar metal welding between stainless and carbon steel

Science.gov (United States)

Ramdan, RD; Koswara, AL; Surasno; Wirawan, R.; Faturohman, F.; Widyanto, B.; Suratman, R.

2018-02-01

The present research focus on the metallurgy and mechanical aspect of dissimilar metal welding.One of the common parameters that significantly contribute to the metallurgical aspect on the metal during welding is heat input. Regarding this point, in the present research, voltage, current and the welding speed has been varied in order to observe the effect of heat input on the metallurgical and mechanical aspect of both welded metals. Welding was conducted by Gas Metal Arc Welding (GMAW) on stainless and carbon steel with filler metal of ER 309. After welding, hardness test (micro-Vickers), tensile test, macro and micro-structure characterization and Energy Dispersive Spectroscopy (EDS) characterization were performed. It was observed no brittle martensite observed at HAZ of carbon steel, whereas sensitization was observed at the HAZ of stainless steel for all heat input variation at the present research. Generally, both HAZ at carbon steel and stainless steel did not affect tensile test result, however the formation of chromium carbide at the grain boundary of HAZ structure (sensitization) of stainless steel, indicate that better process and control of welding is required for dissimilar metal welding, especially to overcome this issue.

Experimental investigation of a low-temperature organic Rankine cycle (ORC) engine under variable heat input operating at both subcritical and supercritical conditions

International Nuclear Information System (INIS)

Kosmadakis, George; Manolakos, Dimitris; Papadakis, George

2016-01-01

Highlights: • Small-scale ORC engine with converted scroll expander is installed at laboratory. • Design suitable for supercritical operation. • ORC engine tested at temperature equal to 95 °C. • Focus is given on expansion and thermal efficiency. • Supercritical operation showed some promising performance. - Abstract: The detailed experimental investigation of an organic Rankine cycle (ORC) is presented, which is designed to operate at supercritical conditions. The net capacity of this engine is almost 3 kW and the laboratory testing of the engine includes the variation of the heat input and of the hot water temperature. The maximum heat input is 48 kW_t_h, while the hot water temperature ranges from 65 up to 100°C. The tests are conducted at the laboratory and the heat source is a controllable electric heater, which can keep the hot water temperature constant, by switching on/off its electrical resistances. The expansion machine is a modified scroll compressor with major conversions, in order to be able to operate with safety at high pressure (or even supercritical at some conditions). The ORC engine is equipped with a dedicated heat exchanger of helical coil design, suitable for such applications. The speeds of the expander and ORC pump are regulated with frequency inverters, in order to control the cycle top pressure and heat input. The performance of all components is evaluated, while special attention is given on the supercritical heat exchanger and the scroll expander. The performance tests examined here concern the variation of the heat input, while the hot water temperature is equal to 95 °C. The aim is to examine the engine performance at the design conditions, as well as at off-design ones. Especially the latter ones are very important, since this engine will be coupled with solar collectors at the final configuration, where the available heat is varied to a great extent. The engine has been measured at the laboratory, where a thermal

Study on a neon cryogenic oscillating heat pipe with long heat transport distance

Science.gov (United States)

Liang, Qing; Li, Yi; Wang, Qiuliang

2017-12-01

An experimental study is carried out to study the heat transfer characteristics of a cryogenic oscillating heat pipe (OHP) with long heat transport distance. The OHP is made up of a capillary tube with an inner diameter of 1.0 mm and an outer diameter of 2.0 mm. The working fluid is neon, and the length of the adiabatic section is 480 mm. Tests are performed with the different heat inputs, liquid filling ratios and condenser temperature. For the cryogenic OHP with a liquid filling ratio of 30.7% at the condenser temperature of 28 K, the effective thermal conductivity is 3466-30,854 W/m K, and the maximum transfer power is 35.60 W. With the increment of the heat input, the effective thermal conductivity of the cryogenic OHP increases at the liquid filling ratios of 30.7% and 38.5%, while it first increases and then decreases at the liquid filling ratios of 15.2% and 23.3%. Moreover, the effective thermal conductivity increases with decreasing liquid filling ratio at the small heat input, and the maximum transfer power first increases and then decreases with increasing liquid filling ratio. Finally, it is found that the thermal performance of the cryogenic OHP can be improved by increasing the condenser temperature.

Effect of Heat Input on Microstructure and Hardness Distribution of Laser Welded Si-Al TRIP-Type Steel

Directory of Open Access Journals (Sweden)

Adam Grajcar

2014-01-01

Full Text Available This study is concerned with issues related to laser welding of Si-Al type TRIP steels with Nb and Ti microadditions. The tests of laser welding of thermomechanically rolled sheet sections were carried out using keyhole welding and a solid-state laser. The tests carried out for various values of heat input were followed by macro- and microscopic metallographic investigations as well as by microhardness measurements of welded areas. A detailed microstructural analysis was carried out in the penetration area and in various areas of the heat affected zone (HAZ. Special attention was paid to the influence of cooling conditions on the stabilisation of retained austenite, the most characteristic structural component of TRIP steels. The tests made it possible to determine the maximum value of heat input preventing the excessive grain growth in HAZ and to identify the areas of the greatest hardness reaching 520 HV0.1.

Effects of Heat Input and Bead Generation Methods on Finite Element Analysis of Cylindrical Multi-Pass Welding Process of Metals

International Nuclear Information System (INIS)

Park, Won Dong; Bahn, Chi Bum; Kim, Ji Hoon

2017-01-01

In this study, a finite element analysis of a cylindrical multi-pass weldment for dissimilar metals was performed. The effects of the heat input method and weld bead generation method were considered. We compared two heat input methods: the heat flux method and the temperature method. We also compared two weld bead generation methods: the element birth method and the quiet element method. Although the results of the thermal analysis show deviations between the two heat input methods, the welding residual stresses were similar. Because the areas exposed to high temperature were similar and the strength of the material was very low in high temperature (above the 1000 ℃), the effects of the weld bead temperature were insignificant. The distributions of the welding residual stress were similar to each other. However, gaps and overlaps occurred on the welding boundary surfaces when the element birth method was applied. The quiet element method is more suitable for a large deformation model in order to simulate a more accurate weld shape.

Effects of Heat Input and Bead Generation Methods on Finite Element Analysis of Cylindrical Multi-Pass Welding Process of Metals

Energy Technology Data Exchange (ETDEWEB)

Park, Won Dong; Bahn, Chi Bum; Kim, Ji Hoon [Pusan Nat’l Univ., Busan (Korea, Republic of)

2017-06-15

In this study, a finite element analysis of a cylindrical multi-pass weldment for dissimilar metals was performed. The effects of the heat input method and weld bead generation method were considered. We compared two heat input methods: the heat flux method and the temperature method. We also compared two weld bead generation methods: the element birth method and the quiet element method. Although the results of the thermal analysis show deviations between the two heat input methods, the welding residual stresses were similar. Because the areas exposed to high temperature were similar and the strength of the material was very low in high temperature (above the 1000 ℃), the effects of the weld bead temperature were insignificant. The distributions of the welding residual stress were similar to each other. However, gaps and overlaps occurred on the welding boundary surfaces when the element birth method was applied. The quiet element method is more suitable for a large deformation model in order to simulate a more accurate weld shape.

Crustal heat production and estimate of terrestrial heat flow in central East Antarctica, with implications for thermal input to the East Antarctic ice sheet

Science.gov (United States)

Goodge, John W.

2018-02-01

Terrestrial heat flow is a critical first-order factor governing the thermal condition and, therefore, mechanical stability of Antarctic ice sheets, yet heat flow across Antarctica is poorly known. Previous estimates of terrestrial heat flow in East Antarctica come from inversion of seismic and magnetic geophysical data, by modeling temperature profiles in ice boreholes, and by calculation from heat production values reported for exposed bedrock. Although accurate estimates of surface heat flow are important as an input parameter for ice-sheet growth and stability models, there are no direct measurements of terrestrial heat flow in East Antarctica coupled to either subglacial sediment or bedrock. As has been done with bedrock exposed along coastal margins and in rare inland outcrops, valuable estimates of heat flow in central East Antarctica can be extrapolated from heat production determined by the geochemical composition of glacial rock clasts eroded from the continental interior. In this study, U, Th, and K concentrations in a suite of Proterozoic (1.2-2.0 Ga) granitoids sourced within the Byrd and Nimrod glacial drainages of central East Antarctica indicate average upper crustal heat production (Ho) of about 2.6 ± 1.9 µW m-3. Assuming typical mantle and lower crustal heat flux for stable continental shields, and a length scale for the distribution of heat production in the upper crust, the heat production values determined for individual samples yield estimates of surface heat flow (qo) ranging from 33 to 84 mW m-2 and an average of 48.0 ± 13.6 mW m-2. Estimates of heat production obtained for this suite of glacially sourced granitoids therefore indicate that the interior of the East Antarctic ice sheet is underlain in part by Proterozoic continental lithosphere with an average surface heat flow, providing constraints on both geodynamic history and ice-sheet stability. The ages and geothermal characteristics of the granites indicate that crust in central

Auroral energy input from energetic electrons and Joule heating at Chatanika

International Nuclear Information System (INIS)

Wickwar, V.B.; Baron, M.J.; Sears, R.D.

1975-01-01

With the incoherent scatter radar at Chatanika, Alaska, a wide variety of measurements can be made related to the ionosphere, magnetosphere, and neutral atmosphere. A significant parameter is the amount of energy transferred from the magnetosphere into the ionosphere and neutral atmosphere during periods of auroral activity. In this report a procedure is examined whereby the incident energy flux of auroral electrons is ascertained from radar measurements. As part of the process radar-determined fluxes are compared with those ascertained from simultaneous photometric observations at 4278 A. The fluxes obtained by both techniques had similar magnitudes and time variations. If it is assumed that the largest uncertainty in the radar/photometer comparison is the effective recombination coefficient, then that coefficient can also be deduced. A value 3times10 -7 cm 3 /s at about 105 km is found, which is in good agreement with other recent determinations during active auroral conditions. This technique is combined with one to ascertain the Joule heating to determine the energy input from the magnetosphere to the ionosphere in a region localized above the radar on March 22, 1973, in the midnight sector. The energy input is continuous at a significant level, i.e., greater than the 3 ergs/cm 2 that could be delivered by the sun, were it overhead. Moreover, at times, each of these inputs became as great as 30 ergs/cm 2 s

The Development and Microstructure Analysis of High Strength Steel Plate NVE36 for Large Heat Input Welding

Science.gov (United States)

Peng, Zhang; Liangfa, Xie; Ming, Wei; Jianli, Li

In the shipbuilding industry, the welding efficiency of the ship plate not only has a great effect on the construction cost of the ship, but also affects the construction speed and determines the delivery cycle. The steel plate used for large heat input welding was developed sufficiently. In this paper, the composition of the steel with a small amount of Nb, Ti and large amount of Mn had been designed in micro-alloyed route. The content of C and the carbon equivalent were also designed to a low level. The technology of oxide metallurgy was used during the smelting process of the steel. The rolling technology of TMCP was controlled at a low rolling temperature and ultra-fast cooling technology was used, for the purpose of controlling the transformation of the microstructure. The microstructure of the steel plate was controlled to be the mixed microstructure of low carbon bainite and ferrite. Large amount of oxide particles dispersed in the microstructure of steel, which had a positive effects on the mechanical property and welding performance of the steel. The mechanical property of the steel plate was excellent and the value of longitudinal Akv at -60 °C is more than 200 J. The toughness of WM and HAZ were excellent after the steel plate was welded with a large heat input of 100-250 kJ/cm. The steel plate processed by mentioned above can meet the requirement of large heat input welding.

Shortage of energy increases profitability of district heating

International Nuclear Information System (INIS)

2003-01-01

Increased demand will cause the price of district heating to increase, but not to the level of the price of electricity. The cheapest heating alternative in Denmark, Norway and Sweden is district heating. In Norway, district heating is developed primarily for commercial buildings and housing cooperatives. Thirty per cent of all buildings under construction are prepared for district heating and the percentage will increase strongly in the coming time. The total net production of district heating in Norway in 2001 was 2000 GWh, which is only a small part of the total potential for district heating

Weld residual stress according to the ways of heat input in the simulation of weld process using finite element analysis

International Nuclear Information System (INIS)

Yang, Jun Seog; Lee, Kyoung Soo; Park, Chi Yong

2008-01-01

This paper is to discuss distribution of welding residual stresses of a ferritic low alloy steel nozzle with dissimilar metal weld using Alloy 82/182. Two Dimensional (2D) thermo-mechanical finite element analyses are carried out to simulate multi-pass welding process on the basis of the detailed and fabrication data. On performing the welding analysis generally, the characteristics on the heat input and heat transfer of weld are affected on the weld residual stress analyses. Thermal analyses in the welding heat cycle process is very important process in weld residual stress analyses. Therefore, heat is rapidly input to the weld pass material, using internal volumetric heat generation, at a rate which raises the peak weld metal temperature to 2200 .deg. C and the base metal adjacent to the weld to about 1400 .deg. C. These are approximately the temperature that the weld metal and surrounding base materials reach during welding. Also, According to the various ways of applying the weld heat source, the predicted residual stress results are compared with measured axial, hoop and radial through-wall profiles in the heat affected zone of test component. Also, those results are compared with those of full 3-dimensional simulation

Investigation of heat flux processes governing the increase of groundwater temperatures beneath cities

Science.gov (United States)

Bayer, P.; Menberg, K.; Zhu, K.; Blum, P.

2012-12-01

In the subsurface of many cities there are widespread and persistent thermal anomalies. These so-called subsurface urban heat islands (UHIs), which also stimulate warming of urban aquifers, are triggered by various processes. Possible heat sources are basements of buildings, leakage of sewage systems, buried district heating networks, re-injection of cooling water and solar irradiation on paved surfaces. In the current study, the reported groundwater temperatures in several Central European cities, such as Berlin, Cologne (Germany) and Zurich (Switzerland) are compared. Available data sets are supplemented by temperature measurements and depth profiles in observation wells. Trend analyses are conducted with time series of groundwater temperatures, and three-dimensional groundwater temperature maps are provided. In all investigated cities, pronounced positive temperature anomalies are present. The distribution of groundwater temperatures appears to be spatially and temporally highly variable. Apparently, the increased heat input into the urban subsurface is controlled by very local and site-specific parameters. In the long-run, the combination of various heat sources results in an extensive temperature increase. In many cases, the maximum temperature elevation is found close to the city center. Regional groundwater temperature differences between the city center and the rural background are up to 5 °C, with local hot spots of even more pronounced anomalies. Particular heat sources, like cooling water injections or case-specific underground constructions, can cause local temperatures > 20 °C in the subsurface. Examination of the long-term variations in isotherm maps shows that temperatures have increased by about 1 °C in the city, as well as in the rural background areas over the last decades. This increase could be reproduced with trend analysis of temperature data gathered from several groundwater wells. Comparison between groundwater and air temperatures in the

The Impacts of Heating Strategy on Soil Moisture Estimation Using Actively Heated Fiber Optics.

Science.gov (United States)

Dong, Jianzhi; Agliata, Rosa; Steele-Dunne, Susan; Hoes, Olivier; Bogaard, Thom; Greco, Roberto; van de Giesen, Nick

2017-09-13

Several recent studies have highlighted the potential of Actively Heated Fiber Optics (AHFO) for high resolution soil moisture mapping. In AHFO, the soil moisture can be calculated from the cumulative temperature ( T cum ), the maximum temperature ( T max ), or the soil thermal conductivity determined from the cooling phase after heating ( λ ). This study investigates the performance of the T cum , T max and λ methods for different heating strategies, i.e., differences in the duration and input power of the applied heat pulse. The aim is to compare the three approaches and to determine which is best suited to field applications where the power supply is limited. Results show that increasing the input power of the heat pulses makes it easier to differentiate between dry and wet soil conditions, which leads to an improved accuracy. Results suggest that if the power supply is limited, the heating strength is insufficient for the λ method to yield accurate estimates. Generally, the T cum and T max methods have similar accuracy. If the input power is limited, increasing the heat pulse duration can improve the accuracy of the AHFO method for both of these techniques. In particular, extending the heating duration can significantly increase the sensitivity of T cum to soil moisture. Hence, the T cum method is recommended when the input power is limited. Finally, results also show that up to 50% of the cable temperature change during the heat pulse can be attributed to soil background temperature, i.e., soil temperature changed by the net solar radiation. A method is proposed to correct this background temperature change. Without correction, soil moisture information can be completely masked by the background temperature error.

Heat input effect of friction stir welding on aluminum alloy AA 6061-T6 welded joint

Czech Academy of Sciences Publication Activity Database

Sedmak, A.; Kumar, R.; Chattopadhyaya, S.; Hloch, Sergej; Tadić, S.; Djurdjević, A. A.; Čeković, I. R.; Dončeva, E.

2016-01-01

Roč. 20, č. 2 (2016), s. 637-641 ISSN 0354-9836 Institutional support: RVO:68145535 Keywords : friction stir welding * defect * heat input * maximum temperature Subject RIV: JQ - Machines ; Tools Impact factor: 1.093, year: 2016 http://www.doiserbia.nb.rs/img/doi/0354-9836/2016/0354-98361500147D.pdf

40 CFR 75.81 - Monitoring of Hg mass emissions and heat input at the unit level.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Monitoring of Hg mass emissions and... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Hg Mass Emission Provisions § 75.81 Monitoring of Hg mass emissions and heat input at the unit level. The owner or operator of the...

Abnormal excess heat observed during Mizuno-type experiments

International Nuclear Information System (INIS)

Fauvarque, Jean-Francois; Clauzon, Pierre Paul; Lalleve, Gerard Jean-Michel

2006-01-01

A simple calorimeter has been designed that works at constant temperature; that of boiling water. Heat Losses can be estimated accurately with an ohmic heater. As expected, losses are independent of the electric power input to the heater and the amount of evaporated water is linearly dependant on the power input. The device has been used to determine the heating power of a plasma electrolysis (the Ohmori-Mizuno experiment). We confirm that in this experiment, the heat output from electrolysis is greater than the electrical power input. The excess energy increases as the electrolysis voltage is increased from 200 up to 350 V (400 V input). The excess energy may be as high as 120 W. (author)

Identification of some cross flow heat exchanger dynamic responses by measurement with low level binary pseudo-random input signals

International Nuclear Information System (INIS)

Corran, E.R.; Cummins, J.D.; Hopkinson, A.

1964-02-01

An experiment was performed to assess the usefulness of the binary cross-correlation method in the context of the identification problem. An auxiliary burner was excited with a discrete interval binary code and the response to the perturbation of the input heat was observed by recording the variations of the primary inlet, primary outlet and secondary outlet temperatures. The observations were analysed to yield cross-correlation functions and frequency responses were subsequently determined between primary inlet and primary outlet temperatures and also between primary inlet and secondary outlet temperatures. The analysis verified (1) that these dynamic responses of this cross flow heat exchanger may be predicted theoretically, (2) in so far as this heat exchanger is representative of the generality of plant, that the binary cross-correlation method provides adequate identification of plant dynamics for control purposes in environments where small input variations and low signal to noise ratio are obligatory. (author)

Development of High Heat Input Welding High Strength Steel Plate for Oil Storage Tank in Xinyu Steel Company

Science.gov (United States)

Zhao, Hemin; Dong, Fujun; Liu, Xiaolin; Xiong, Xiong

This essay introduces the developed high-heat input welding quenched and tempered pressure vessel steel 12MnNiVR for oil storage tank by Xinyu Steel, which passed the review by the Boiler and Pressure Vessel Standards Technical Committee in 2009. The review comments that compared to the domestic and foreign similar steel standard, the key technical index of enterprise standard were in advanced level. After the heat input of 100kJ/cm electro-gas welding, welded points were still with excellent low temperature toughness at -20°C. The steel plate may be constructed for oil storage tank, which has been permitted by thickness range from 10 to 40mm, and design temperature among -20°C-100°C. It studied microstructure genetic effects mechanical properties of the steel. Many production practices indicated that the mechanical properties of products and the steel by stress relief heat treatment of steel were excellent, with pretreatment of hot metal, converter refining, external refining, protective casting, TMCP and heat treatment process measurements. The stability of performance and matured technology of Xinyu Steel support the products could completely service the demand of steel constructed for 10-15 million cubic meters large oil storage tank.

Increase of COP for heat transformer in water purification systems. Part II - Without increasing heat source temperature

International Nuclear Information System (INIS)

Romero, R.J.; Siqueiros, J.; Huicochea, A.

2007-01-01

The integration of a water purification system allows a heat transformer to increase the actual coefficient of performance, by the reduction of the amount of heat supplied by unit of heat. A new defined COP called COP WP is proposed for the present system, which considers the fraction of heat recycled. Simulation with proven software compares the performance of the modeling of an absorption heat transformer for water purification (AHTWP) operating with water/lithium bromide, as working fluid-absorbent pair. Plots of enthalpy-based coefficients of performance (COP ET ) and water purification coefficient of performance (COP WP ) are shown against absorber temperature for several thermodynamic operating conditions. The results showed that the proposed (AHTWP) system is capable of increasing the original value of COP ET up to 1.6 times its original value by recycling energy from a water purification system. The proposed COP WP allows increments for COP values from any experimental data for water purification or for any other distillation system integrated to a heat transformer, regardless of actual COP A value or working fluid-absorbent pair

Effect of weld metal chemistry and heat input on the structure and properties of duplex stainless steel welds

Energy Technology Data Exchange (ETDEWEB)

Muthupandi, V.; Bala Srinivasan, P.; Seshadri, S.K.; Sundaresan, S

2003-10-15

The excellent combination of strength and corrosion resistance in duplex stainless steels (DSS) is due to their strict composition control and microstructural balance. The ferrite-austenite ratio is often upset in DSS weld metals owing to the rapid cooling rates associated with welding. To achieve the desired ferrite-austenite balance and hence properties, either the weld metal composition and/or the heat input is controlled. In the current work, a low heat input process viz., EBW and another commonly employed process, gas tungsten-arc welding have been employed for welding of DSS with and without nickel enhancement. Results show that (i) chemical composition has got a greater influence on the ferrite-austenite ratio than the cooling rate, (ii) and even EBW which is considered an immature process in welding of DSS, can be employed provided means of filler addition could be devised.

40 CFR 75.82 - Monitoring of Hg mass emissions and heat input at common and multiple stacks.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Monitoring of Hg mass emissions and... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Hg Mass Emission Provisions § 75.82 Monitoring of Hg mass emissions and heat input at common and multiple stacks. (a) Unit...

Working Fluids for Increasing Capacities of Heat Pipes

Science.gov (United States)

Chao, David F.; Zhang, Nengli

2004-01-01

A theoretical and experimental investigation has shown that the capacities of heat pipes can be increased through suitable reformulation of their working fluids. The surface tensions of all of the working fluids heretofore used in heat pipes decrease with temperature. As explained in more detail below, the limits on the performance of a heat pipe are associated with the decrease in the surface tension of the working fluid with temperature, and so one can enhance performance by reformulating the working fluid so that its surface tension increases with temperature. This improvement is applicable to almost any kind of heat pipe in almost any environment. The heat-transfer capacity of a heat pipe in its normal operating-temperature range is subject to a capillary limit and a boiling limit. Both of these limits are associated with the temperature dependence of surface tension of the working fluid. In the case of a traditional working fluid, the decrease in surface tension with temperature causes a body of the liquid phase of the working fluid to move toward a region of lower temperature, thus preventing the desired spreading of the liquid in the heated portion of the heat pipe. As a result, the available capillary-pressure pumping head decreases as the temperature of the evaporator end of the heat pipe increases, and operation becomes unstable. Water has widely been used as a working fluid in heat pipes. Because the surface tension of water decreases with increasing temperature, the heat loads and other aspects of performance of heat pipes that contain water are limited. Dilute aqueous solutions of long-chain alcohols have shown promise as substitutes for water that can offer improved performance, because these solutions exhibit unusual surface-tension characteristics: Experiments have shown that in the cases of an aqueous solution of an alcohol, the molecules of which contain chains of more than four carbon atoms, the surface tension increases with temperature when the

Study on the Heating Behavior of Fe_3O_4-Embedded Thermoplastic Polyurethane Adhesive Film via Induction heating

International Nuclear Information System (INIS)

Bae, Duck Hwan; Shon, Min Young; Oh, Sang Taek; Kim, Gu Ni

2016-01-01

The heating behavior of thermoplastic polyurethane adhesive (TPU) embedded by nanometer or micrometer Fe_3O_4 particle is examined by induction heating. The effects of the size and the amount of Fe_3O_4 particle, TPU film thickness, and input power of the induction heater were examined on heating behaviors of TPU. The quantity of heat generated in the TPU films increased with the amount of Fe_3O_4 particles, film thickness, or input power. On the other hand, the quantity of heat generation of TPU is decreased with increasing Fe_3O_4 size. We confirmed that the mechanism of hysteresis led to heat loss in the nanometer and micrometer-sized Fe_3O_4 particles, and it was the key controller of the quantity of heat generated in the Fe_3O_4 particle-embedded TPU films by induction heating.

Fast increases in urban sewage inputs to rivers of Indonesia

NARCIS (Netherlands)

Suwarno, D.; Löhr, A.; Kroeze, C.; Widianarko, B.

2014-01-01

We present estimates for nitrogen (N) and phosphorus (P) sewage inputs to 19 Indonesian rivers for 1970–2050. Future trends are based on the four scenarios of the Millennium Ecosystem Assessment. Our results indicate a rapid increase in N and P pollution from sewage over time. In 1970, N and P

Economic and CO2 mitigation impacts of promoting biomass heating systems: An input-output study for Vorarlberg, Austria

International Nuclear Information System (INIS)

Madlener, Reinhard; Koller, Martin

2007-01-01

This paper reports on an empirical investigation about the economic and CO 2 mitigation impacts of bioenergy promotion in the Austrian federal province of Vorarlberg. We study domestic value-added, employment, and fiscal effects by means of a static input-output analysis. The bioenergy systems analysed comprise biomass district heating, pellet heating, and automated wood chip heating systems, as well as logwood stoves and boilers, ceramic stoves, and buffer storage systems. The results indicate that gross economic effects are significant, regarding both investment and operation of the systems, and that the negative economic effects caused by the displacement of conventional decentralised heating systems might be in the order of 20-40%. Finally, CO 2 mitigation effects are substantial, contributing already in 2004 around 35% of the 2010 CO 2 mitigation target of the Land Vorarlberg for all renewable energy sources

After heat removing system of a nuclear reactor

International Nuclear Information System (INIS)

Hayashi, Takao; Yamada, Masao; Ohashi, Kazutaka.

1994-01-01

In a variable conductance heat pipe of an after heat removing system, an evaporation portion and a condensator are connected by a steam diffusing path for an operation fluid and a liquid condensate recycling path. Further, incondensible gases are sealed at the inside together with the operation fluid, and a gas reservoir for the incondensible gases is disposed at the downstream of a condensation portion. If heat input is applied to the evaporation portion of the heat pipe, the incondensible gases are separated to form a boundary between both of them. When the amount of heat applied is small, the incondensible gases partially seal the condensation portion to form a local condensation insensitive portion, so that a heat conductance can be suppressed low. On the other hand, as the amount of heat inputted is increased, the incondensible gases are compressed, the heat conduction area of the condensation portion is increased and a heat conductance is increased to conduct self-control so as to increase heat transfer performance of the heat pipe. Then, the liquid condensate is recycled to the evaporation portion by spontaneous dripping of the condensate itself without wick, thereby enabling to conduct automatic switching so as to increase the heat dissipation amount to maximum. (N.H.)

Programmed heating of coke ovens for increased coke size

Energy Technology Data Exchange (ETDEWEB)

Jenkins, D.R.; Mahoney, M.R. [University of Newcastle, Callaghan, NSW (Australia)

2010-11-15

Large, uniform sized coke is desirable for blast furnace use. It has previously been shown that the coke oven flue temperature in the first few hours of coking is a key determinant of coke size. In this paper, the authors present a new programmed heating approach, which is called pulsed heating, aiming to increase coke mean size at a given average flue temperature. The approach takes into account the charging sequence in coke oven batteries and the authors demonstrate how existing operating practice can be modified in batteries with suitable heating systems to achieve the desired heating programme. A mathematical model of fissure formation provides a prediction of the increase in coke mean size using pulsed heating, compared with standard heating. Pilot scale experiments have also been performed to validate the modelling approach. The results of the modelling indicate that the mean coke size can be increased by several millimetres in some cases, although results from the pilot scale show that pulsed heating increases coke size, but by a smaller amount than that predicted by the model. The potential advantages and limitations of pulsed heating are discussed, as well as opportunities for further investigation of the approach.

Flow patterns and heat transfer characteristics of flat plate pulsating heat pipes with various asymmetric and aspect ratios of the channels

International Nuclear Information System (INIS)

Jang, Dong Soo; Lee, Joo Seong; Ahn, Jae Hwan; Kim, Dongwoo; Kim, Yongchan

2017-01-01

Highlights: • Flat plate pulsating heat pipes with asymmetric and aspect ratios were tested. • Flow patterns were investigated according to channel geometry and flow condition. • Heat transfer characteristics were analyzed with various heat inputs. • Optimum asymmetric and aspect ratios were suggested for maximum thermal performance. - Abstract: The thermal performance of flat plate pulsating heat pipes (PHPs) in compact electronic devices can be improved by adopting asymmetric channels with increased pressure differences and an unbalanced driving force. The objective of this study is to investigate the heat transfer characteristics of flat plate PHPs with various asymmetric ratios and aspect ratios in the channels. The thermal performance and flow pattern of the flat plate PHPs were measured by varying the asymmetric ratio from 1.0 to 4.0, aspect ratio from 2.5 to 5.0, and heat input from 2 to 28 W. The effects of the asymmetric ratio and aspect ratio on the thermal resistance were analyzed with the measured evaporator temperature and flow patterns at various heat inputs. With heat inputs of 6 W and 12 W, the optimum asymmetric ratio and aspect ratio for the flat plate PHPs were determined to be 4.0 and 2.5, respectively. With the heat input of 18 W, the optimum asymmetric ratio and aspect ratio were determined to be 1.5 and 2.5, respectively.

Thermoregulatory efficiency is increased after heat acclimation in tropical natives.

Science.gov (United States)

Magalhães, Flávio C; Passos, Renata L F; Fonseca, Michele A; Oliveira, Kenya P M; Ferreira-Júnior, João B; Martini, Angelo R P; Lima, Milene R M; Guimarães, Juliana B; Baraúna, Valério G; Silami-Garcia, Emerson; Rodrigues, Luiz O C

2010-01-01

To evaluate the effects of heat acclimation on sweat rate redistribution and thermodynamic parameters, 9 tropical native volunteers were submitted to 11 days of exercise-heat exposures (40+/-0 degrees C and 45.1+/-0.2% relative humidity). Sudomotor function was evaluated by measuring total and local (forehead, chest, arm, forearm, and thigh) sweat rates, local sweat sodium concentration, and mean skin and rectal temperatures. We also calculated heat production (H), heat storage (S), heat exchange by radiation (R) and by convection (C), evaporated sweat (E(sw)), sweating efficiency (eta(sw)), skin wettedness (w(sk)), and the ratio between the heat storage and the sum of heat production and heat gains by radiation and convection (S/(H+R+C)). The heat acclimation increased the whole-body sweat rate and reduced the mean skin temperature. There were changes in the local sweat rate patterns: on the arm, forearm, and thigh it increased significantly from day 1 to day 11 (all p<0.05) and the sweat rates from the forehead and the chest showed a small nonsignificant increase (p=0.34 and 0.17, respectively). The relative increase of local sweat rates on day 11 was not different among the sites; however, when comparing the limbs (arm, forearm, and thigh) with the trunk (forehead and chest), there was a significant higher increase in the limbs (32+/-5%) in comparison to the trunk (11+/-2%, p=0.001). After the heat acclimation period we observed higher w(sk) and E(sw) and reduced S/(H+R+C), meaning greater thermoregulatory efficiency. The increase in the limb sweat rate, but not the increase in the trunk sweat rate, correlated with the increased w(sk), E(sw), and reduced S/(H+R+C) (p<0.05 to all). Altogether, it can be concluded that heat acclimation increased the limbs' sweat rates in tropical natives and that this increase led to increased loss of heat through evaporation of sweat and this higher sweat evaporation was related to higher thermoregulatory efficiency.

Study on the Heating Behavior of Fe{sub 3}O{sub 4}-Embedded Thermoplastic Polyurethane Adhesive Film via Induction heating

Energy Technology Data Exchange (ETDEWEB)

Bae, Duck Hwan; Shon, Min Young [Pukyong National University, Busan (Korea, Republic of); Oh, Sang Taek; Kim, Gu Ni [Korea Institute of Footwear and Leather Technology, Busan (Korea, Republic of)

2016-08-15

The heating behavior of thermoplastic polyurethane adhesive (TPU) embedded by nanometer or micrometer Fe{sub 3}O{sub 4} particle is examined by induction heating. The effects of the size and the amount of Fe{sub 3}O{sub 4} particle, TPU film thickness, and input power of the induction heater were examined on heating behaviors of TPU. The quantity of heat generated in the TPU films increased with the amount of Fe{sub 3}O{sub 4} particles, film thickness, or input power. On the other hand, the quantity of heat generation of TPU is decreased with increasing Fe{sub 3}O{sub 4} size. We confirmed that the mechanism of hysteresis led to heat loss in the nanometer and micrometer-sized Fe{sub 3}O{sub 4} particles, and it was the key controller of the quantity of heat generated in the Fe{sub 3}O{sub 4} particle-embedded TPU films by induction heating.

Temper-bead repair-welding of neutron-irradiated reactor (pressure) vessel by low-heat-input TIG and YAG laser welding

International Nuclear Information System (INIS)

Nakata, Kiyotomo; Ozawa, Masayoshi; Kamo, Kazuhiko

2006-01-01

Weldability in neutron-irradiated low alloy steel for reactor (pressure) vessel has been studied by temper-bead repair-welding of low-heat-input TIG and YAG laser welding. A low alloy steel and its weld, and stainless steel clad and nickel (Ni)-based alloy clad were irradiated in a materials test reactor (LVR-15, Czech Republic) up to 1.4 x 10 24 n/m 2 (>1 MeV) at 290degC, which approximately corresponds to the maximum neutron fluence of 60-year-operation plants' vessels. The He concentration in the irradiated specimens was estimated to be up to 12.9 appm. The repair-welding was carried out by TIG and YAG laser welding at a heat input from 0.06 to 0.86 MJ/m. The mechanical tests of tensile, impact, side bend and hardness were carried out after the repair-welding. Cracks were not observed in the irradiated low alloy steel and its weld by temper-bead repair-welding. Small porosities were formed in the first and second layers of the repair-welds of low alloy steel (base metal). However, only a few porosities were found in the repair-welds of the weld of low alloy steel. From the results of mechanical tests, the repair-welding could be done in the irradiated weld of low alloy steel containing a He concentration up to 12.9 appm, although repair-welding could be done in base metal of low alloy steel containing up to only 1.7 appmHe. On the other hand, cracks occurred in the heat affected zones of stainless steel and Ni-based alloy clads by repair-welding, except by YAG laser repair-welding at a heat input of 0.06 MJ/m in stainless steel clad containing 1.7 appmHe. Based on these results, the determination processes were proposed for optimum parameters of repair-welding of low alloy steel and clad used for reactor (pressure) vessel. (author)

A statistical survey of heat input parameters into the cusp thermosphere

Science.gov (United States)

Moen, J. I.; Skjaeveland, A.; Carlson, H. C.

2017-12-01

Based on three winters of observational data, we present those ionosphere parameters deemed most critical to realistic space weather ionosphere and thermosphere representation and prediction, in regions impacted by variability in the cusp. The CHAMP spacecraft revealed large variability in cusp thermosphere densities, measuring frequent satellite drag enhancements, up to doublings. The community recognizes a clear need for more realistic representation of plasma flows and electron densities near the cusp. Existing average-value models produce order of magnitude errors in these parameters, resulting in large under estimations of predicted drag. We fill this knowledge gap with statistics-based specification of these key parameters over their range of observed values. The EISCAT Svalbard Radar (ESR) tracks plasma flow Vi , electron density Ne, and electron, ion temperatures Te, Ti , with consecutive 2-3 minute windshield-wipe scans of 1000x500 km areas. This allows mapping the maximum Ti of a large area within or near the cusp with high temporal resolution. In magnetic field-aligned mode the radar can measure high-resolution profiles of these plasma parameters. By deriving statistics for Ne and Ti , we enable derivation of thermosphere heating deposition under background and frictional-drag-dominated magnetic reconnection conditions. We separate our Ne and Ti profiles into quiescent and enhanced states, which are not closely correlated due to the spatial structure of the reconnection foot point. Use of our data-based parameter inputs can make order of magnitude corrections to input data driving thermosphere models, enabling removal of previous two fold drag errors.

Experimental investigation into heating and airflow in trombe walls and solar chimneys

International Nuclear Information System (INIS)

Habib, A.; Burek, S.

2006-01-01

Trombe Walls and solar chimneys are examples of passive solar air heating systems. However, the airflow and thermal efficiency characteristics of this type of system are not well understood, and partly for this reason, they are not commonly utilised. This paper reports on an experimental investigation into buoyancy-driven convection in a test rig designed to simulate the operation of a passive solar collector. The test rig comprised a vertical open-ended channel, approximately 1a square, heated from one side. The channel depth could be varied from 20mm to 110mm, and heating inputs varied from 200W to 1000W. Temperatures and airflow rates were measured and recorded, to characterise both steady-state and transient performance. The principal findings are: 1. Time constants (for heating)ranged typically between 30 and 70 minutes. 2. Flow regimes were mainly laminar (Reynolds number varing from ∼500 to ∼4000, depending on heat input and channel depth. 3. The thermal efficiency (as a solar collector and the heat transfer coefficient were functions of heat input, and were not depended on the channel depth. 4. The mass flow rate through the channel increased bath as the heat input increased and as the channel depth increased. The paper presents these findings and discusses their implications in more detail.(Author)

High-Power Laser Cutting of Steel Plates: Heat Affected Zone Analysis

Directory of Open Access Journals (Sweden)

Imed Miraoui

2016-01-01

Full Text Available The thermal effect of CO2 high-power laser cutting on cut surface of steel plates is investigated. The effect of the input laser cutting parameters on the melted zone depth (MZ, the heat affected zone depth (HAZ, and the microhardness beneath the cut surface is analyzed. A mathematical model is developed to relate the output process parameters to the input laser cutting parameters. Three input process parameters such as laser beam diameter, cutting speed, and laser power are investigated. Mathematical models for the melted zone and the heat affected zone depth are developed by using design of experiment approach (DOE. The results indicate that the input laser cutting parameters have major effect on melted zone, heat affected zone, and microhardness beneath cut surface. The MZ depth, the HAZ depth, and the microhardness beneath cut surface increase as laser power increases, but they decrease with increasing cutting speed. Laser beam diameter has a negligible effect on HAZ depth but it has a remarkable effect on MZ depth and HAZ microhardness. The melted zone depth and the heat affected zone depth can be reduced by increasing laser cutting speed and decreasing laser power and laser beam diameter.

Effect of Heat Input During Disk Laser Bead-On-Plate Welding of Thermomechanically Rolled Steel on Penetration Characteristics and Porosity Formation in the Weld Metal

Directory of Open Access Journals (Sweden)

Lisiecki A.

2016-03-01

Full Text Available The paper presents a detailed analysis of the influence of heat input during laser bead-on-plate welding of 5.0 mm thick plates of S700MC steel by modern Disk laser on the mechanism of steel penetration, shape and depth of penetration, and also on tendency to weld porosity formation. Based on the investigations performed in a wide range of laser welding parameters the relationship between laser power and welding speed, thus heat input, required for full penetration was determined. Additionally the relationship between the laser welding parameters and weld quality was determined.

Combination study of operation characteristics and heat transfer mechanism for pulsating heat pipe

International Nuclear Information System (INIS)

Cui, Xiaoyu; Zhu, Yue; Li, Zhihua; Shun, Shende

2014-01-01

Pulsating heat pipe (PHP) is becoming a promising heat transfer device for the application like electronics cooling. However, due to its complicated operation mechanism, the heat transfer properties of the PHP still have not been fully understood. This study experimentally investigated on a closed-loop PHP charged with four types of working fluids, deionized water, methanol, ethanol and acetone. Combined with the visualization experimental results from the open literature, the operation characteristics and the corresponding heat transfer mechanisms for different heat inputs (5 W up to 100 W) and different filling ratios (20% up to 95%) have been presented and elaborated. The results show that heat-transfer mechanism changed with the transition of operation patterns; before valid oscillation started, the thermal resistance was not like that described in the open literature where it decreased almost linearly, but would rather slowdown descending or even change into rise first before further decreasing (i.e. an inflection point existed); when the heat input further increased to certain level, e.g. 65 W or above, there presented a limit of heat-transfer performance which was independent of the types of working fluids and the filling ratios, but may be related to the structure, the material, the size and the inclination of the PHP. - Highlights: •The thermal mechanisms altered accordingly with the operation features in the PHP. •Unlike conventional heat pipes, continuous temperature soaring would not happen in the PHP. •Before the oscillation start-up, there existed a heat-transfer limit for the relatively stagnated flow in the PHP. •A limit of thermal performance existed in the PHP at relatively high heat inputs

Low heat input welding of nickel superalloy GTD-111 with Inconel 625 filler metal

Energy Technology Data Exchange (ETDEWEB)

Athiroj, Athittaya; Wangyao, Panyawat; Hartung, Fritz; Lothongkum, Gobboon [Chulalongkorn Univ., Bangkok (Thailand). Dept. of Metallurgical Engineering

2018-03-01

GTD-111 precipitation-strengthened nickel-based superalloy is widely used in blades of gas turbine engines which operate at high temperature and in a hot localized corrosion atmosphere. After long-term exposure to high temperature, γ' precipitate is known to exhibit catastrophic changes in size and distribution which cause deterioration of its properties and failure of the component. In this study, a damaged blade removed from a land-based gas turbine generator was subjected to nonpre-heat-treated GTAW and laser welding repair with various welding powers in the range of 135 to 295 J x mm{sup -1}, followed by post-weld heat treatment (PWHT) at 1473 K for 7200 s and strain aging at 1118 K for 86 400 s. Results show no significant relationship between welding powers, size and area fraction of the γ' precipitate in the fcc γ matrix in both GTAW and laser-welded specimens. The final γ' precipitate size and distribution depend mainly on PWHT parameters as γ' precipitates in all GTAW and laser welded specimens showed similar size and area fraction independently of the heat input from welding. Unmixed zones are observed in all laser welding specimens which may cause preferential weld corrosion during service. Microcrack occurrence due to welding and PWHT processes is also discussed.

An experimental study of the enhanced heating capacity of an electric heat pump (EHP) using the heat recovered from a gas engine generator

Energy Technology Data Exchange (ETDEWEB)

Kim, Cheol Min; Chang, Se Dong [HAC R and D Laboratory, LG Electronics, 327-23 Gasan-Dong, Geumcheon-gu, Seoul 153-802 (Korea); Lee, Jaekeun; Hwang, Yujin [School of Mechanical Engineering, Pusan National University, San 30, Changjeon-Dong, Keumjeong-Ku, Busan 609-735 (Korea)

2009-11-15

This paper is concerned with the effect of recovered heat on the heating capacity of an Electric Heat Pump (EHP), which is supplied with electric power and recovered heat from a gas engine generator system. Two methods of supplying recovery heat are examined: (i) to the refrigerant with the discharge line heat exchanger (HEX), and (ii) to the refrigerant of the evaporator with the sub-evaporator. Heating capacity, input power and coefficient of performance (COP) were investigated and compared for each heat recovery method. Conclusively, we found that the second method was most reasonable to recover wasted heat and increased system COP by 215%. (author)

Specimen Test of Large-Heat-Input Fusion Welding Method for Use of SM570TMCP

Directory of Open Access Journals (Sweden)

Dongkyu Lee

2015-01-01

Full Text Available In this research, the large-heat-input welding conditions optimized to use the rear plate and the high-performance steel of SM570TMCP, a new kind of steel suitable for the requirements of prospective customers, are proposed. The goal of this research is to contribute to securing the welding fabrication optimized to use the high-strength steel and rear steel plates in the field of construction industry in the future. This research is judged to contribute to securing the welding fabrication optimized to use the high-strength steel and rear steel plates in the field of construction industry in the future.

Weldability with Process Parameters During Fiber Laser Welding of a Titanium Plate (II) - The Effect of Control of Heat Input on Weldability -

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Do; Kim, Ji Sung [Korea Maritime and Ocean Univ., Busan (Korea, Republic of)

2016-12-15

Laser welding is a high-density energy welding method. Hence, deep penetration and high welding speed can be realized with lower heat input as compared with conventional welding. The heat input of a CW laser welding is determined by laser power and welding speed. In this study, bead and lap welding of 0.5 mmt pure titanium was performed using a fiber laser. Its weldability with laser power and welding speed was evaluated. Penetration, bead width, joining length, and bead shape were investigated, and the mechanical properties were examined through tensile-shear strength tests. Welds with sound joining length were obtained when the laser power and welding speed were respectively 0.5 kW and 2.5 m/min, and 1.5 kW and 6 m/min, and the weld obtained at low output presented better ductility than that obtained at high output.

Weldability with Process Parameters During Fiber Laser Welding of a Titanium Plate (II) - The Effect of Control of Heat Input on Weldability -

International Nuclear Information System (INIS)

Kim, Jong Do; Kim, Ji Sung

2016-01-01

Laser welding is a high-density energy welding method. Hence, deep penetration and high welding speed can be realized with lower heat input as compared with conventional welding. The heat input of a CW laser welding is determined by laser power and welding speed. In this study, bead and lap welding of 0.5 mmt pure titanium was performed using a fiber laser. Its weldability with laser power and welding speed was evaluated. Penetration, bead width, joining length, and bead shape were investigated, and the mechanical properties were examined through tensile-shear strength tests. Welds with sound joining length were obtained when the laser power and welding speed were respectively 0.5 kW and 2.5 m/min, and 1.5 kW and 6 m/min, and the weld obtained at low output presented better ductility than that obtained at high output

Responses of Lithium-Modified Bath to a Shift in Heat Input/Output Balance and Observation of Freeze-Lining Formation During the Heat Balance Shift

Science.gov (United States)

Liu, Jingjing; Taylor, Mark; Dorreen, Mark

2018-02-01

In the aluminum electrolysis process, new industrial aluminum/electricity power markets demand a new cell technology to extend the cell heat balance and amperage operating window of smelters by shifting the steady states. The current work investigates the responses of lithium-modified bath system when the input/output balance is shifted in a laboratory analogue to the industrial heat balance shift. Li2CO3 is added to the cryolite-AlF3-CaF2-Al2O3 system as a bath modifier. A freeze deposit is formed on a `cold finger' dipped into the bath and investigated by X-ray diffraction analysis and electron probe X-ray microanalysis. The macro- and micro-structure of the freeze lining varies with the bath superheat (bath temperature minus bath liquidus temperature) and an open crystalline layer with entrapped liquid dominates the freeze thickness. Compared with the cryolite-AlF3-CaF2-Al2O3 bath system, the lithium-modified bath freeze is more sensitive to the heat balance shift. This freeze investigation provides primary information to understand the variation of the side ledge in an industrial cell when the lithium-modified bath system is used.

Heat input effect on the microstructural transformation and mechanical properties in GTAW welds of a 409L ferritic stainless steel

Energy Technology Data Exchange (ETDEWEB)

Delgado, J. A.; Ambriz, R. R.; Cuenca-Alvarez, R.; Alatorre, N.; Curiel, F. F.

2016-10-01

Welds without filler metal and welds using a conventional austenitic stainless steel filler metal (ER308L) were performed to join a ferritic stainless steel with Gas Tungsten Arc Welding process (GTAW). Welding parameters were adjusted to obtain three different heat input values. Microstructure reveals the presence of coarse ferritic matrix and martensite laths in the Heat Affected Zone (HAZ). Dilution between filler and base metal was correlated with the presence of austenite, martensite and ferrite in the weld metal. Weld thermal cycles were measured to correlate the microstructural transformation in the HAZ. Microhardness measurements (maps and profiles) allow to identify the different zones of the welded joints (weld metal, HAZ, and base metal). Comparing the base metal with the weld metal and the HAZ, a hardness increment (∼172 HV{sub 0}.5 to ∼350 HV{sub 0}.5 and ∼310 HV{sub 0}.5, respectively) was observed, which has been attributed to the martensite formation. Tensile strength of the welded joints without filler metal increased moderately with respect to base metal. In contrast, ductility was approximately 25% higher than base metal, which provided a toughness improvement of the welded joints. (Author)

An asymptotic-preserving stochastic Galerkin method for the radiative heat transfer equations with random inputs and diffusive scalings

Energy Technology Data Exchange (ETDEWEB)

Jin, Shi, E-mail: sjin@wisc.edu [Department of Mathematics, University of Wisconsin-Madison, Madison, WI 53706 (United States); Institute of Natural Sciences, Department of Mathematics, MOE-LSEC and SHL-MAC, Shanghai Jiao Tong University, Shanghai 200240 (China); Lu, Hanqing, E-mail: hanqing@math.wisc.edu [Department of Mathematics, University of Wisconsin-Madison, Madison, WI 53706 (United States)

2017-04-01

In this paper, we develop an Asymptotic-Preserving (AP) stochastic Galerkin scheme for the radiative heat transfer equations with random inputs and diffusive scalings. In this problem the random inputs arise due to uncertainties in cross section, initial data or boundary data. We use the generalized polynomial chaos based stochastic Galerkin (gPC-SG) method, which is combined with the micro–macro decomposition based deterministic AP framework in order to handle efficiently the diffusive regime. For linearized problem we prove the regularity of the solution in the random space and consequently the spectral accuracy of the gPC-SG method. We also prove the uniform (in the mean free path) linear stability for the space-time discretizations. Several numerical tests are presented to show the efficiency and accuracy of proposed scheme, especially in the diffusive regime.

Scaling of divertor heat flux profile widths in DIII-D

International Nuclear Information System (INIS)

Lasnier, C.J.; Makowski, M.A.; Boedo, J.A.; Allen, S.L.; Brooks, N.H.; Hill, D.N.; Leonard, A.W.; Watkins, J.G.; West, W.P.

2011-01-01

New scalings of the dependence of divertor heat flux peak and profile width, important parameters for the design of future large tokamaks, have been obtained from recent DIII-D experiments. We find the peak heat flux depends linearly on input power, decreases linearly with increasing density, and increases linearly with plasma current. The profile width has a weak dependence on input power, is independent of density up to the onset of detachment, and is inversely proportional to the plasma current. We compare these results with previously published scalings, and present mathematical expressions incorporating these results.

Heat Roadmap Europe

DEFF Research Database (Denmark)

Connolly, David; Mathiesen, Brian Vad; Lund, Henrik

2015-01-01

This document is a summary of the key technical inputs for the modelling of the heat strategy for Europe outlined in the latest Heat Roadmap Europe studies [1, 2]. These studies quantify the impact of alternative heating strategies for Europe in 2030 and 2050. The study is based on geographical...... information systems (GIS) and energy system analyses. In this report, the inputs for other modelling tools such as PRIMES are presented, in order to enable other researches to generate similar heating scenarios for Europe. Although Heat Roadmap Europe presents a complete heat strategy for Europe, which...... includes energy efficiency, individual heating units (such as boilers and heat pumps), and heat networks, the recommendations here are primarily relating to the potential and modelling of district heating. Although other solutions will play a significant role in decarbonising the heating and cooling sector...

Effect of Heat Flux on the Specimen Temperature of an LBE Capsule

International Nuclear Information System (INIS)

Kang, Y. H.; Park, S. J.; Cho, M. S.; Choo, K. N.; Lee, Y. S.

2011-01-01

For application of high-temperature irradiation tests in the HANARO reactor for Gen IV reactor material development, a number of newly designed LBE capsules have been investigated at KAERI since 2008. Recent study on heat transfer experiment of an LBE capsule with a single heater has shown that the specimen temperature of the mock-up increased linearly with an increase of heat input. The work highlighted only the heat transfer capability of an LBE capsule with a single heater as a simulated specimen in a liquid metal medium. Hence, a new LBE capsule with multi specimen sets has been designed and fabricated for the heat transfer experiment of an LBE capsule of 11M-01K. In this paper, a series of thermal analyses and heat transfer experiments for a newly designed LBE capsule was implemented to study the effect of an increase in the value of heat input and its influence on temperature distribution in the capsule mock-up

Attention enhances contrast appearance via increased input baseline of neural responses.

Science.gov (United States)

Cutrone, Elizabeth K; Heeger, David J; Carrasco, Marisa

2014-12-30

Covert spatial attention increases the perceived contrast of stimuli at attended locations, presumably via enhancement of visual neural responses. However, the relation between perceived contrast and the underlying neural responses has not been characterized. In this study, we systematically varied stimulus contrast, using a two-alternative, forced-choice comparison task to probe the effect of attention on appearance across the contrast range. We modeled performance in the task as a function of underlying neural contrast-response functions. Fitting this model to the observed data revealed that an increased input baseline in the neural responses accounted for the enhancement of apparent contrast with spatial attention. © 2014 ARVO.

Microbial respiration, but not biomass, responded linearly to increasing light fraction organic matter input: Consequences for carbon sequestration.

Science.gov (United States)

Rui, Yichao; Murphy, Daniel V; Wang, Xiaoli; Hoyle, Frances C

2016-10-18

Rebuilding 'lost' soil carbon (C) is a priority in mitigating climate change and underpinning key soil functions that support ecosystem services. Microorganisms determine if fresh C input is converted into stable soil organic matter (SOM) or lost as CO 2 . Here we quantified if microbial biomass and respiration responded positively to addition of light fraction organic matter (LFOM, representing recent inputs of plant residue) in an infertile semi-arid agricultural soil. Field trial soil with different historical plant residue inputs [soil C content: control (tilled) = 9.6 t C ha -1 versus tilled + plant residue treatment (tilled + OM) = 18.0 t C ha -1 ] were incubated in the laboratory with a gradient of LFOM equivalent to 0 to 3.8 t C ha -1 (0 to 500% LFOM). Microbial biomass C significantly declined under increased rates of LFOM addition while microbial respiration increased linearly, leading to a decrease in the microbial C use efficiency. We hypothesise this was due to insufficient nutrients to form new microbial biomass as LFOM input increased the ratio of C to nitrogen, phosphorus and sulphur of soil. Increased CO 2 efflux but constrained microbial growth in response to LFOM input demonstrated the difficulty for C storage in this environment.

Effects of Symmetrically Arranged Heat Sources on the Heat Release Performance of Extruded-Type Heat Sinks

Energy Technology Data Exchange (ETDEWEB)

Ku, Min Ye [Chonbuk National Univ., Chonju (Korea, Republic of)

2016-02-15

In this study we investigated the effects of symmetrically arranged heat sources on the heat release performances of extruded-type heat sinks through experiments and thermal fluid simulations. Also, based on the results we suggested a high-efficiency and cost-effective heat sink for a solar inverter cooling system. In this parametric study, the temperatures between heaters on the base plate and the heat release rates were investigated with respect to the arrangements of heat sources and amounts of heat input. Based on the results we believe that the use of both sides of the heat sink is the preferred method for releasing the heat from the heat source to the ambient environment rather than the use of a single side of the heat sink. Also from the results, it is believed that the symmetric arrangement of the heat sources is recommended to achieve a higher rate of heat transfer. From the results of the thermal fluid simulation, it was possible to confirm the qualitative agreement with the experimental results. Finally, quantitative comparison with respect to mass flow rates, heat inputs, and arrangements of the heat source was also performed.

Faster turnover of new soil carbon inputs under increased atmospheric CO2.

Science.gov (United States)

van Groenigen, Kees Jan; Osenberg, Craig W; Terrer, César; Carrillo, Yolima; Dijkstra, Feike A; Heath, James; Nie, Ming; Pendall, Elise; Phillips, Richard P; Hungate, Bruce A

2017-10-01

Rising levels of atmospheric CO 2 frequently stimulate plant inputs to soil, but the consequences of these changes for soil carbon (C) dynamics are poorly understood. Plant-derived inputs can accumulate in the soil and become part of the soil C pool ("new soil C"), or accelerate losses of pre-existing ("old") soil C. The dynamics of the new and old pools will likely differ and alter the long-term fate of soil C, but these separate pools, which can be distinguished through isotopic labeling, have not been considered in past syntheses. Using meta-analysis, we found that while elevated CO 2 (ranging from 550 to 800 parts per million by volume) stimulates the accumulation of new soil C in the short term (soil C pool over either temporal scale. Our results are inconsistent with predictions of conventional soil C models and suggest that elevated CO 2 might increase turnover rates of new soil C. Because increased turnover rates of new soil C limit the potential for additional soil C sequestration, the capacity of land ecosystems to slow the rise in atmospheric CO 2 concentrations may be smaller than previously assumed. © 2017 John Wiley & Sons Ltd.

Effects of heat input on pitting corrosion in super duplex stainless steel weld metals

Science.gov (United States)

Shin, Yong taek; Shin, Hak soo; Lee, Hae woo

2012-12-01

Due to the difference in reheating effects depending on the heat input of subsequent weld passes, the microstructure of the weld metal varies between acicular type austenite and a mixture of polygonal type and grain boundary mixed austenite. These microstructural changes may affect the corrosion properties of duplex stainless steel welds. This result indicates that the pitting resistance of the weld can be strongly influenced by the morphology of the secondary austenite phase. In particular, the ferrite phase adjacent to the acicular type austenite phase shows a lower Pitting Resistance Equivalent (PRE) value of 25.3, due to its lower chromium and molybdenum contents, whereas the secondary austenite phase maintains a higher PRE value of more than 38. Therefore, it can be inferred that the pitting corrosion is mainly due to the formation of ferrite phase with a much lower PRE value.

Experimental Investigation of A Heat Pipe-Assisted Latent Heat Thermal Energy Storage System

Science.gov (United States)

Tiari, Saeed; Mahdavi, Mahboobe; Qiu, Songgang

2016-11-01

In the present work, different operation modes of a latent heat thermal energy storage system assisted by a heat pipe network were studied experimentally. Rubitherm RT55 enclosed by a vertical cylindrical container was used as the Phase Change Material (PCM). The embedded heat pipe network consisting of a primary heat pipe and an array of four secondary heat pipes were employed to transfer heat to the PCM. The primary heat pipe transports heat from the heat source to the heat sink. The secondary heat pipes transfer the extra heat from the heat source to PCM during charging process or retrieve thermal energy from PCM during discharging process. The effects of heat transfer fluid (HTF) flow rate and temperature on the thermal performance of the system were investigated for both charging and discharging processes. It was found that the HTF flow rate has a significant effect on the total charging time of the system. Increasing the HTF flow rate results in a remarkable increase in the system input thermal power. The results also showed that the discharging process is hardly affected by the HTF flow rate but HTF temperature plays an important role in both charging and discharging processes. The authors would like to acknowledge the financial supports by Temple University for the project.

Deficiency of heat shock transcription factor 1 suppresses heat stress-associated increase in slow soleus muscle mass of mice.

Science.gov (United States)

Ohno, Y; Egawa, T; Yokoyama, S; Nakai, A; Sugiura, T; Ohira, Y; Yoshioka, T; Goto, K

2015-12-01

Effects of heat shock transcription factor 1 (HSF1) deficiency on heat stress-associated increase in slow soleus muscle mass of mice were investigated. Both HSF1-null and wild-type mice were randomly assigned to control and heat-stressed groups. Mice in heat-stressed group were exposed to heat stress (41 °C for 60 min) in an incubator without anaesthesia. Significant increase in wet and dry weights, and protein content of soleus muscle in wild-type mice was observed seven days after the application of the heat stress. However, heat stress had no impact on soleus muscle mass in HSF1-null mice. Neither type of mice exhibited much effect of heat stress on HSF mRNA expression (HSF1, HSF2 and HSF4). On the other hand, heat stress upregulated heat shock proteins (HSPs) at the mRNA (HSP72) and protein (HSP72 and HSP110) levels in wild-type mice, but not in HSF1-null mice. The population of Pax7-positive nuclei relative to total myonuclei of soleus muscle in wild-type mice was significantly increased by heat stress, but not in HSF1-null mice. Furthermore, the absence of HSF1 gene suppressed heat stress-associated phosphorylation of Akt and p70 S6 kinase (p-p70S6K) in soleus muscle. Heat stress-associated increase in skeletal muscle mass may be induced by HSF1 and/or HSF1-mediated stress response that activates muscle satellite cells and Akt/p70S6K signalling pathway. © 2015 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Analysis of boundary layer control by heat transfer strips using an asymptotic approach to the PSE

Energy Technology Data Exchange (ETDEWEB)

Brooker, A.M.H.; Severin, J. [Technische Univ. Chemnitz (Germany). Technische Thermodynamik; Herwig, H. [Technische Univ. Hamburg-Harburg, Hamburg (Germany). Abt. Technische Thermodynamik

2002-05-01

The effect of heating strips on the stability of boundary layer flow over a flat plate is investigated. Heating strips alter the flow stability through the temperature dependence of the fluid properties. A stability study is carried out using the parabolized stability equations (PSE) that calculates the effects of temperature dependent fluid properties in terms of asymptotic expansions based on the total heat input. The leading order influence is obtained as a general result and, for the particular Prandtl number taken, is independent of any special set of property laws. In a fluid for which the intrinsic viscosity increases with temperature and the density decreases with temperature (such as air) the results show that the optimal location for a heating strip to stabilise the flow is upstream of the neutral point. The optimal location moves further upstream as the total heat input level is increased. For a given heat input widening the heating strip further stabilises the flow. Finally, the potential of the asymptotic method as a tool for further analysis of the flow is discussed. (orig.)

Thermodynamic and experimental study on heat transfer mechanism of miniature loop heat pipe with water-copper nanofluid

Science.gov (United States)

Wang, Xiao-wu; Wan, Zhen-ping; Tang, Yong

2018-02-01

A miniature loop heat pipe (mLHP) is a promising device for heat dissipation of electronic products. Experimental study of heat transfer performance of an mLHP employing Cu-water nanofluid as working fluid was conducted. It is found that, when input power is above 25 W, the temperature differences between the evaporator wall and vapor of nanofluid, Te - Tv, and the total heat resistance of mLHP using nanofluid are always lower than those of mLHP using de-ionized water. The values of Te - Tv and total heat resistance of mLHP using nanofluid with concentration 1.5 wt. % are the lowest, while when the input power is 25 W, the values of Te - Tv and total heat resistance of mLHP using de-ionized water are even lower than those of mLHP using nanofluid with concentration 2.0 wt. %. At larger input power, the dominant interaction is collision between small bubbles and nanoparticles which can facilitate heat transfer. While at lower input power, nanoparticles adhere to the surface of large bubble. This does not benefit boiling heat transfer. For mLHP using nanofluid with larger concentration, for example 2.0%, the heat transfer may even be worse compared with using de-ionized water at lower input power. The special structure of the mLHP in this study, two separated chambers in the evaporator, produces an extra pressure difference and contributes to the heat transfer performance of the mLHP.

Increasing economic benefits by load-shifting of electrical heat pumps

OpenAIRE

Laveyne, Joannes; Zwaenepoel, Brecht; Van Eetvelde, Greet; Vandevelde, Lieven

2014-01-01

Electrical heating is still widely used in the process industry. While the use of immersion heaters for the production of hot water or steam is declining, the adoption rate of electrical heat pumps is increasing rapidly. Heat pumps show great flexibility and potential for energy savings, e.g. through low temperature waste heat recuperation. In combination with thermal storage they also allow for load shifting. Because their main power source is electricity, which up to now cannot be stored ef...

Prototype implementation and experimental analysis of water heating using recovered waste heat of chimneys

Directory of Open Access Journals (Sweden)

Mahmoud Khaled

2015-03-01

Full Text Available This work discusses a waste heat recovery system (WHRS applied to chimneys for heating water in residential buildings. A prototype illustrating the suggested system is implemented and tested. Different waste heat scenarios by varying the quantity of burned firewood (heat input are experimented. The temperature at different parts of the WHRS and the gas flow rates of the exhaust pipes are measured. Measurements showed that the temperature of 95 L tank of water can be increased by 68 °C within one hour. Obtained results show that the convection and radiation exchanges at the bottom surface of the tank have a considerable impact on the total heat transfer rate of the water (as high as 70%.

Radiant heat increases piglets’ use of the heated creep area on the critical days after birth

DEFF Research Database (Denmark)

Larsen, Mona Lilian Vestbjerg; Thodberg, Karen; Pedersen, Lene Juul

2017-01-01

The aim of the present study was to investigate how piglets’ use of a creep area is affected by using radiant heat compared to an incandescent light bulb. It was hypothesised that radiant heat would increase the use of the creep area. Twenty litters were randomly assigned to one of two heat sources...... in the creep area: (1) an incandescent light bulb (STANDARD, n=10) or (2) a radiant heat source (RADIANT, n=10) with five of each type of heat source in each of two batches. Observations on piglets’ position in the pen were made by scan sampling every ten minutes in a 4-hour period from 1100 to 1500 h on day 1......–7, 14 and 21 post partum. A higher percentage of piglets in the creep area was seen for RADIANT litters compared to STANDARD litters on day 2 (P=0.002) and day 3 (P=0.005), and percentage of piglets in the creep area increased for RADIANT litters from day 1 to 2 (P

CASKETSS-HEAT: a finite difference computer program for nonlinear heat conduction problems

International Nuclear Information System (INIS)

Ikushima, Takeshi

1988-12-01

A heat conduction program CASKETSS-HEAT has been developed. CASKETSS-HEAT is a finite difference computer program used for the solution of multi-dimensional nonlinear heat conduction problems. Main features of CASKETSS-HEAT are as follows. (1) One, two and three-dimensional geometries for heat conduction calculation are available. (2) Convection and radiation heat transfer of boundry can be specified. (3) Phase change and chemical change can be treated. (4) Finned surface heat transfer can be treated easily. (5) Data memory allocation in the program is variable according to problem size. (6) The program is a compatible heat transfer analysis program to the stress analysis program SAP4 and SAP5. (7) Pre- and post-processing for input data generation and graphic representation of calculation results are available. In the paper, brief illustration of calculation method, input data and sample calculation are presented. (author)

Potential for increased wind-generated electricity utilization using heat pumps in urban areas

International Nuclear Information System (INIS)

Waite, Michael; Modi, Vijay

2014-01-01

Highlights: • Large-scale wind power and increased electric heat pumps were evaluated. • A deterministic model of wind power and electricity demand was developed. • Sub-models for space heating and domestic hot water demand were developed. • Increased use of heat pumps can improve the viability of large-scale wind power. • Larger wind power capacity can meet a target utilization rate with more heat pumps. - Abstract: The U.S. has substantial wind power potential, but given wind’s intermittent availability and misalignment with electricity demand profiles, large-scale deployment of wind turbines could result in high electricity costs due to energy storage requirements or low utilization rates. While fuel switching and heat pumps have been proposed as greenhouse gas (GHG) emissions and energy reduction strategies at the building scale, this paper shows that heat pump adoption could have additional system-wide benefits by increasing the utilization of wind-generated electricity. A model was developed to evaluate the effects of coupling large-scale wind power installations in New York State with increased use of electric heat pumps to meet a portion of space heating and domestic hot water (DHW) demands in New York City. The analysis showed significant increases in wind-generated electricity utilization with increased use of heat pumps, allowing for higher installed capacity of wind power. One scenario indicates that 78.5% annual wind-generated electricity utilization can be achieved with 3 GW of installed wind power capacity generated electricity equal to 20% of existing NYC annual electricity demand; if 20% of space heating and DHW demands are provided by heat pumps, the 78.5% utilization rate can be achieved with an increase of total wind power capacity to 5 GW. Therefore, this integrated supply–demand approach could provide additional system-wide emissions reductions

Heating patterns during cancer heat therapy as a function of blood flow

International Nuclear Information System (INIS)

Mendecki, J.; Friedenthal, E.; Botstein, C.; Sterzer, F.; Paglione, R.W.

1984-01-01

Heating patterns as a function of regional blood flow were evaluated in healthy tissues with different vascular characteristics as well as in a variety of tumors submitted to microwave and RF-induced hyperthermia. Generally, faster heating and slower cooling was demonstrated for tumors. Definite correlation was found between the power needed to heat given tissue volume to a specific temperature and the ability of this tissue to dissipate heat via vascular flow. The measurements show that during the early phase of heating of tumors temperature rises slowly up to about 40 0 C. indicating good heat exchanges but that at this level rapid increase of temperature occurs for relatively small increments of power input. It is suggested that blood flow in malignant tissue remains competent and responsive to low grade heating, but that at higher temperature levels, in contrast to normal tissue, tumor blood flow rapidly decreases indicating compromised vascular system. Implication for treatment protocols are discussed

Numerical routine for magnetic heat pump cascading

DEFF Research Database (Denmark)

Filonenko, Konstantin; Lei, Tian; Engelbrecht, Kurt

Heat pumps use low-temperature heat absorbed from the energy source to create temperature gradient (TG) across the energy sink. Magnetic heat pumps (MHP) can perform this function through operating active magnetic regeneration (AMR) cycle. For building heating, TGs of up to a few K might...... and 3 K. Changing the number of MHPs, we optimized input parameters to achieve maximum heating powers. We have found that both maximum heating power and COP decrease together with number of heat pumps, but the TGs and the temperature span can be largely increased. References [1] M. Tahavori et al., “A...... be necessary, which is hardly achievable with a single MHP and such techniques as cascading are required. Series and parallel cascading increase the AMR span and heating power, respectively, but do not change TG. Therefore, the intermediate type of cascading was proposed with individual MHPs separately...

Increased mortality associated with extreme-heat exposure in King County, Washington, 1980-2010

Science.gov (United States)

Isaksen, Tania Busch; Fenske, Richard A.; Hom, Elizabeth K.; Ren, You; Lyons, Hilary; Yost, Michael G.

2016-01-01

Extreme heat has been associated with increased mortality, particularly in temperate climates. Few epidemiologic studies have considered the Pacific Northwest region in their analyses. This study quantified the historical (May to September, 1980-2010) heat-mortality relationship in the most populous Pacific Northwest County, King County, Washington. A relative risk (RR) analysis was used to explore the relationship between heat and all-cause mortality on 99th percentile heat days, while a time series analysis, using a piece-wise linear model fit, was used to estimate the effect of heat intensity on mortality, adjusted for temporal trends. For all ages, all causes, we found a 10 % (1.10 (95 % confidence interval (CI), 1.06, 1.14)) increase in the risk of death on a heat day versus non-heat day. When considering the intensity effect of heat on all-cause mortality, we found a 1.69 % (95 % CI, 0.69, 2.70) increase in the risk of death per unit of humidex above 36.0 °C. Mortality stratified by cause and age produced statistically significant results using both types of analyses for: all-cause, non-traumatic, circulatory, cardiovascular, cerebrovascular, and diabetes causes of death. All-cause mortality was statistically significantly modified by the type of synoptic weather type. These results demonstrate that heat, expressed as humidex, is associated with increased mortality on heat days, and that risk increases with heat's intensity. While age was the only individual-level characteristic found to modify mortality risks, statistically significant increases in diabetes-related mortality for the 45-64 age group suggests that underlying health status may contribute to these risks.

Flow laminarization and heat transfer crisis in tubes while intense heating of turbulent flow of a gas endothermically dissociating on a wall

International Nuclear Information System (INIS)

Kurganov, V.A.; Gladuntsov, A.I.

1977-01-01

Analysed are the experimental data obtained for heat transfer to gaseous dissociating ammonium (NH 3 ) under heating in round pipes (steel Kh18N10T) at developed eddying input flow and marginal condition of heat supply gsub(c) approximately equal to const in the ranges of the following parameters: p=3-10 atm; Tsub(input)=310-720 K; Tsub(c) ( 3 ; gsub(c)/-anti rho W 8.8 kJ/kg; gsub(c)/(anti rho WCsub(p) sub(input)Tsub(input)) (<=) 0.0104; 1/d (<=) 150 (where Tsub(c) is the wall temperature, gsub(c) the heat flow density on wall, and anti rho W velocity). The discussion involves phenomena of worsened heat transfer at high heat loads. The authors show the basic relationship between these phenomena and laminarization of the near-wall flow at the input site of the pipe. The regularities of heat transfer were noted to undergo substantial transformation under laminarized flow

Application of sorption heat pumps for increasing of new power sources efficiency

Science.gov (United States)

Vasiliev, L.; Filatova, O.; Tsitovich, A.

2010-07-01

In the 21st century the way to increase the efficiency of new sources of energy is directly related with extended exploration of renewable energy. This modern tendency ensures the fuel economy needs to be realized with nature protection. The increasing of new power sources efficiency (cogeneration, trigeneration systems, fuel cells, photovoltaic systems) can be performed by application of solid sorption heat pumps, regrigerators, heat and cold accumulators, heat transformers, natural gas and hydrogen storage systems and efficient heat exchangers.

Experimental investigation of an active magnetic regenerative heat circulator applied to self-heat recuperation technology

International Nuclear Information System (INIS)

Kotani, Yui; Kansha, Yasuki; Ishizuka, Masanori; Tsutsumi, Atsushi

2014-01-01

An experimental investigation into an active magnetic regenerative (AMR) heat circulator based on self-heat recuperation technology, was conducted to evaluate its energy saving potential in heat circulation. In an AMR heat circulator, magnetocaloric effect is applied to recuperate the heat exergy of the process fluid. The recuperated heat can be reused to heat the feed process fluid and realize self-heat recuperation. In this paper, AMR heat circulator has newly been constructed to determine the amount of heat circulated when applied to self-heat recuperation and the energy consumption of the heat circulator. Gadolinium and water was used as the magnetocaloric working material and the process fluid, respectively. The heat circulated amount was determined by measuring the temperature of the process fluid and gadolinium. The net work input for heat circulation was obtained from the magnetizing and demagnetizing forces and the distance travelled by the magnetocaloric bed. The results were compared with the minimum work input needed for heat circulation derived from exergy loss during heat exchange. It was seen that the experimentally obtained value was close to the minimum work input needed for heat circulation. - Highlights: • AMR heat circulator has newly been constructed for experimental evaluation. • Heat circulation in the vicinity of Curie temperature was observed. • Energy consumption of an AMR heat circulator has been measured. • Energy saving for processes near Curie temperature of working material was seen

Microstructural, Mechanical, and Electrochemical Analysis of Duplex and Superduplex Stainless Steels Welded with the Autogenous TIG Process Using Different Heat Input

Directory of Open Access Journals (Sweden)

Gláucio Soares da Fonseca

2017-12-01

Full Text Available Duplex Stainless Steels (DSS and Superduplex Stainless Steels (SDSS have a strong appeal in the petrochemical industry. These steels have excellent properties, such as corrosion resistance and good toughness besides good weldability. Welding techniques take into account the loss of alloying elements during the process, so this loss is usually compensated by the addition of a filler metal rich in alloying elements. A possible problem would be during the welding of these materials in adverse conditions in service, where the operator could have difficulties in welding with the filler metal. Therefore, in this work, two DSS and one SDSS were welded, by autogenous Tungsten Inert Gas (TIG, i.e., without addition of a filler metal, by three different heat inputs. After welding, microstructural, mechanical, and electrochemical analysis was performed. The microstructures were characterized for each welding condition, with the aid of optical microscopy (OM. Vickers hardness, Charpy-V, and cyclic polarization tests were also performed. After the electrochemical tests, the samples were analyzed by scanning electron microscopy (SEM. The SDSS welded with high heat input kept the balance of the austenite and ferrite, and toughness above the limit value. The hardness values remain constant in the weld regions and SDSS is the most resistant to corrosion.

Heat pump heating with heat pumps driven by combustion engines or turbines

Energy Technology Data Exchange (ETDEWEB)

Hein, K

1977-01-27

The heat pump described is driven by a gas Otto cycle engine, or a gas- or light- or heavy-oil fired Diesel engine. The claim refers to the use of waste heat of the engines by feeding into the input circuit of the heat pump. In addition, a drive by an electrical motor-generator or power production can be selected at times of peak load in the electrical supply network.

Salt appetite is not increased in summer heat.

Science.gov (United States)

Leshem, Micah

2017-01-01

We tested the hypothesis that salt appetite increases in summer heat due to increased sodium loss due to increased drinking and perspiration. A test battery in the same sample of healthy young people tested in summer and winter revealed no seasonal differences in salt appetite (or fluid intake) despite a 10 °C rise in mean environmental temperature. Unexpectedly, sweet preference is reduced in summer. Copyright © 2016 Elsevier Ltd. All rights reserved.

Capillary pumped loop body heat exchanger

Science.gov (United States)

Swanson, Theodore D. (Inventor); Wren, deceased, Paul (Inventor)

1998-01-01

A capillary pumped loop for transferring heat from one body part to another body part, the capillary pumped loop comprising a capillary evaporator for vaporizing a liquid refrigerant by absorbing heat from a warm body part, a condenser for turning a vaporized refrigerant into a liquid by transferring heat from the vaporized liquid to a cool body part, a first tube section connecting an output port of the capillary evaporator to an input of the condenser, and a second tube section connecting an output of the condenser to an input port of the capillary evaporator. A wick may be provided within the condenser. A pump may be provided between the second tube section and the input port of the capillary evaporator. Additionally, an esternal heat source or heat sink may be utilized.

A one-dimensional heat transfer model for parallel-plate thermoacoustic heat exchangers

NARCIS (Netherlands)

de Jong, Anne; Wijnant, Ysbrand H.; de Boer, Andries

2014-01-01

A one-dimensional (1D) laminar oscillating flow heat transfer model is derived and applied to parallel-plate thermoacoustic heat exchangers. The model can be used to estimate the heat transfer from the solid wall to the acoustic medium, which is required for the heat input/output of thermoacoustic

High Resolution Modeling of the Thermospheric Response to Energy Inputs During the RENU-2 Rocket Flight

Science.gov (United States)

Walterscheid, R. L.; Brinkman, D. G.; Clemmons, J. H.; Hecht, J. H.; Lessard, M.; Fritz, B.; Hysell, D. L.; Clausen, L. B. N.; Moen, J.; Oksavik, K.; Yeoman, T. K.

2017-12-01

The Earth's magnetospheric cusp provides direct access of energetic particles to the thermosphere. These particles produce ionization and kinetic (particle) heating of the atmosphere. The increased ionization coupled with enhanced electric fields in the cusp produces increased Joule heating and ion drag forcing. These energy inputs cause large wind and temperature changes in the cusp region. The Rocket Experiment for Neutral Upwelling -2 (RENU-2) launched from Andoya, Norway at 0745UT on 13 December 2015 into the ionosphere-thermosphere beneath the magnetic cusp. It made measurements of the energy inputs (e.g., precipitating particles, electric fields) and the thermospheric response to these energy inputs (e.g., neutral density and temperature, neutral winds). Complementary ground based measurements were made. In this study, we use a high resolution two-dimensional time-dependent non hydrostatic nonlinear dynamical model driven by rocket and ground based measurements of the energy inputs to simulate the thermospheric response during the RENU-2 flight. Model simulations will be compared to the corresponding measurements of the thermosphere to see what they reveal about thermospheric structure and the nature of magnetosphere-ionosphere-thermosphere coupling in the cusp. Acknowledgements: This material is based upon work supported by the National Aeronautics and Space Administration under Grants: NNX16AH46G and NNX13AJ93G. This research was also supported by The Aerospace Corporation's Technical Investment program

The scaling of edge parameters in jet with plasma input power

International Nuclear Information System (INIS)

Erents, S.K.; McCracken, G.M.; Harbour, P.J.; Clement, S.; Summers, D.D.R.; Tagle, J.A.; Kock, L. de

1989-01-01

The scaling of edge parameters of density and temperature with central density and ohmic power in JET has been presented previously for the discrete limiter geometry and more recently for the new belt limiter configuration. However, the scaling with plasma current (I p ) is difficult to interpret because varying I p does not only change the input power but also the safety factor qs and consequently the SOL thickness. The use of additional heating at constant current allows more direct observation of the effects of changing heating power. In this paper we present data in which the plasma input power is increased by ICRH, (Pt<20MW), using a 3MA target plasma, and compare data for different plasma currents using discrete and belt limiter geometries. Edge data is presented from Langmuir probes in tiles at the top of the torus, when the tokamak is operated in single null magnetic separatrix (divertor) mode, as well as for probes in the main plasma boundary to contrast these data with limiter data. (author) 3 refs., 4 figs

NASA Lewis steady-state heat pipe code users manual

International Nuclear Information System (INIS)

Tower, L.K.

1992-06-01

The NASA Lewis heat pipe code has been developed to predict the performance of heat pipes in the steady state. The code can be used as a design tool on a personal computer or, with a suitable calling routine, as a subroutine for a mainframe radiator code. A variety of wick structures, including a user input option, can be used. Heat pipes with multiple evaporators, condensers, and adiabatic sections in series and with wick structures that differ among sections can be modeled. Several working fluids can be chosen, including potassium, sodium, and lithium, for which the monomer-dimer equilibrium is considered. The code incorporates a vapor flow algorithm that treats compressibility and axially varying heat input. This code facilitates the determination of heat pipe operating temperatures and heat pipe limits that may be encountered at the specified heat input and environment temperature. Data are input to the computer through a user-interactive input subroutine. Output, such as liquid and vapor pressures and temperatures, is printed at equally spaced axial positions along the pipe as determined by the user

PCBs and DDE, but not PBDEs, increase with trophic level and marine input in nestling bald eagles

International Nuclear Information System (INIS)

Hamish Elliott, Kyle; Cesh, Lillian S.; Dooley, Jessica A.; Letcher, Robert J.; Elliott, John E.

2009-01-01

Concentrations of persistent contaminants often vary widely among individuals within a population. We hypothesized that such variation was caused mainly by differences in diet (biomagnification) and in coastal systems by the tendency of marine systems to act as contaminant sinks. We examined the relationship between contaminant concentrations and stable isotope ratios in nestling plasma from an apex predator with a particularly broad diet. Our study included freshwater, estuarine, inshore and pelagic breeding sites. Bald eagles (Haliaeetus leucocephalus) at the pelagic marine sites showed high trophic level and marine input, eagles at the freshwater sites showed low trophic level and marine input, and eagles at the estuarine and inshore marine sites had intermediate values. The relationship between trophic level and marine input may reflect longer food chains in pelagic compared to terrestrial ecosystems. ΣPCBs and DDE concentrations generally increased with trophic level and marine input, with the exception of the freshwater sites, while ΣPBDEs, hydroxylated-PBDEs and hydroxylated-PCBs increased with marine input, but were independent of trophic level. The relationships for ΣPCBs and DDE were often slightly stronger with marine input than trophic level, suggesting that oceanographic processes may be more important than trophic level. At freshwater locations, spatial variation may be more important than trophic level due to the heterogeneity of contaminant profiles between feeding locations (lakes, rivers, agricultural fields). Adults had similar isotopic composition to their chicks but higher contamination. Based on nests where prey composition was determined independently, isotopic enrichment values for nestling plasma were 1.6 ± 0.1 (δ 15 N) and - 0.4 ±0.2 (δ 13 C). We conclude that trophic level and marine influence are significant factors influencing PCB and DDE concentrations in eagles. However, trophic level in particular did not influence PBDEs

Nuclear heat sources for cryogenic refrigerator applications

International Nuclear Information System (INIS)

Raab, B.; Schock, A.; King, W.G.; Kline, T.; Russo, F.A.

1975-01-01

Spacecraft cryogenic refrigerators require thermal inputs on the order of 1000 W. First, the characteristics of solar-electric and radioisotope heat source systems for supplying this thermal input are compared. Then the design of a 238 Pu heat source for this application is described, and equipment for shipping and handling the heat source is discussed. (LCL)

Increased hospital admissions associated with extreme-heat exposure in King County, Washington, 1990-2010.

Science.gov (United States)

Isaksen, Tania Busch; Yost, Michael G; Hom, Elizabeth K; Ren, You; Lyons, Hilary; Fenske, Richard A

2015-01-01

Increased morbidity and mortality have been associated with extreme heat events, particularly in temperate climates. Few epidemiologic studies have considered the impact of extreme heat events on hospitalization rates in the Pacific Northwest region. This study quantifies the historic (May to September 1990-2010) heat-morbidity relationship in the most populous Pacific Northwest County, King County, Washington. A relative risk (RR) analysis was used to explore the association between heat and all non-traumatic hospitalizations on 99th percentile heat days, whereas a time series analysis using a piecewise linear model approximation was used to estimate the effect of heat intensity on hospitalizations, adjusted for temporal trends and day of the week. A non-statistically significant 2% [95% CI: 1.02 (0.98, 1.05)] increase in hospitalization risk, on a heat day vs. a non-heat day, was noted for all-ages and all non-traumatic causes. When considering the effect of heat intensity on admissions, we found a statistically significant 1.59% (95% CI: 0.9%, 2.29%) increase in admissions per degree increase in humidex above 37.4°C. Admissions stratified by cause and age produced statistically significant results with both relative risk and time series analyses for nephritis and nephrotic syndromes, acute renal failure, and natural heat exposure hospitalizations. This study demonstrates that heat, expressed as humidex, is associated with increased hospital admissions. When stratified by age and cause of admission, the non-elderly age groups (<85 years) experience significant risk for nephritis and nephrotic syndromes, acute renal failure, natural heat exposure, chronic obstructive pulmonary disease, and asthma hospitalizations.

Evaluation of AISI 4140 Steel Repair Without Post-Weld Heat Treatment

Science.gov (United States)

Silva, Cleiton C.; de Albuquerque, Victor H. C.; Moura, Cícero R. O.; Aguiar, Willys M.; Farias, Jesualdo P.

2009-04-01

The present work evaluates the two-layer technique on the heat affected zone (HAZ) of AISI 4140 steel welded with different heat input levels between the first and second layer. The weld heat input levels selected by the Higuchi test were 5/5, 5/10, and 15/5 kJ/cm. The evaluation of the refining and/or tempering of the coarsened grain HAZ of the first layer was carried out using metallographic tests, microhardness measurements, and the Charpy-V impact test. The tempering of the first layer was only reached when the weld heat input ratio was 5/5 kJ/cm. The results of the Charpy-V impact test showed that the two-layer technique was efficient, from the point of view of toughness, since the toughness values reached were greater than the base metal for all weld heat input ratios applied. The results obtained indicate that the best performance of the two-layer deposition technique was for the weld heat input ratio 5/5 kJ/cm employing low heat input.

Evaluating the potential of process sites for waste heat recovery

International Nuclear Information System (INIS)

Oluleye, Gbemi; Jobson, Megan; Smith, Robin; Perry, Simon J.

2016-01-01

Highlights: • Analysis considers the temperature and duties of the available waste heat. • Models for organic Rankine cycles, absorption heat pumps and chillers proposed. • Exploitation of waste heat from site processes and utility systems. • Concept of a site energy efficiency introduced. • Case study presented to illustrate application of the proposed methodology. - Abstract: As a result of depleting reserves of fossil fuels, conventional energy sources are becoming less available. In spite of this, energy is still being wasted, especially in the form of heat. The energy efficiency of process sites (defined as useful energy output per unit of energy input) may be increased through waste heat utilisation, thereby resulting in primary energy savings. In this work, waste heat is defined and a methodology developed to identify the potential for waste heat recovery in process sites; considering the temperature and quantity of waste heat sources from the site processes and the site utility system (including fired heaters and, the cogeneration, cooling and refrigeration systems). The concept of the energy efficiency of a site is introduced – the fraction of the energy inputs that is converted into useful energy (heat or power or cooling) to support the methodology. Furthermore, simplified mathematical models of waste heat recovery technologies using heat as primary energy source, including organic Rankine cycles (using both pure and mixed organics as working fluids), absorption chillers and absorption heat pumps are developed to support the methodology. These models are applied to assess the potential for recovery of useful energy from waste heat. The methodology is illustrated for an existing process site using a case study of a petroleum refinery. The energy efficiency of the site increases by 10% as a result of waste heat recovery. If there is an infinite demand for recovered energy (i.e. all the recoverable waste heat sources are exploited), the site

Heat transfer in an evaporation-condensation system in simulated weightlessness conditions

Science.gov (United States)

Bologa, M. K.; Grosu, F. P.; Kozhevnikov, I. V.; Motorin, O. V.; Polikarpov, A. A.

2017-10-01

The process of heat transfer in an evaporation-condensation system (ECS) at circulation of dielectric liquid in a closed thermoelectrohydrodynamic (TEHD) loop consisting of an evaporator, a condenser and electrohydrodynamic (EHD) pump for pumping of heat carrier, is considered. Previously, the authors studied the dependence of heat transfer on the angle of rotation of TEHD loop in a vertical plane. The report contains the results of studies of heat transfer at electrohydrodynamic pumping of the heat carrier (8% solution of acetone in Freon 113) in the condenser area by means of EHD pump of “cone-cone” type. All elements of the ECS are arranged in a horizontal plane and the heat transfer from the heater to the condenser without EHD pumping is impossible. A pulsating heat carrier flow mode, depending on the heat input and the voltage applied to the pump, takes place at EHD pumping. As the input power is decreasing the frequency of the coolant pulsations as well as the departure diameter and number of vapour bubbles are also decreasing. At some critical heat input the pulsations disappear and the transition from turbulent mode to the laminar one takes place causing the decrease of the heat transfer coefficient. The increase of the pumping flow rate by raising the voltage applied to the EHD pump, results in a partial suppression of boiling. The maximum intensification of heat transfer is reached at pulsation frequency of 1.25 Hz. The maximum heat flow from the heater was 4.2·104 W/m2. Graphical representation and the physical interpretation of the results, which reflect the essence of the process, are given.

Experimental Study of Heat Transfer Enhancements from Array of Alternate Rectangular Dwarf Fins at Different Inclinations

Science.gov (United States)

Awasarmol, Umesh Vandeorao; Pise, Ashok T.

2018-02-01

The main objective of this experimental work is to investigate and compare heat transfer enhancement of alternate dwarf fin array at different angles of inclination. In this study, the steady state heat transfer from the full length fin arrays and alternate dwarf fin arrays are measured in natural convection and radiation environment. Largest increase in the Nusselt number was achieved with alternate dwarf fin at angle of orientation 90°, which shows about 28% enhanced heat transfer coefficient as opposed to the full-length fin array with 25% saving in material. In case of non-black FAB, contribution of radiation heat transfer is found to be very small nearly within 1% of the heater input. After coating lamp black contribution of radiation heat transfer is found to increase to about 3-4% of the heater input in the range of temperatures considered in this study.

A stock-flow consistent input-output model with applications to energy price shocks, interest rates, and heat emissions

Science.gov (United States)

Berg, Matthew; Hartley, Brian; Richters, Oliver

2015-01-01

By synthesizing stock-flow consistent models, input-output models, and aspects of ecological macroeconomics, a method is developed to simultaneously model monetary flows through the financial system, flows of produced goods and services through the real economy, and flows of physical materials through the natural environment. This paper highlights the linkages between the physical environment and the economic system by emphasizing the role of the energy industry. A conceptual model is developed in general form with an arbitrary number of sectors, while emphasizing connections with the agent-based, econophysics, and complexity economics literature. First, we use the model to challenge claims that 0% interest rates are a necessary condition for a stationary economy and conduct a stability analysis within the parameter space of interest rates and consumption parameters of an economy in stock-flow equilibrium. Second, we analyze the role of energy price shocks in contributing to recessions, incorporating several propagation and amplification mechanisms. Third, implied heat emissions from energy conversion and the effect of anthropogenic heat flux on climate change are considered in light of a minimal single-layer atmosphere climate model, although the model is only implicitly, not explicitly, linked to the economic model.

Energy input and dissipation in a temperate lake during the spring transition

Science.gov (United States)

Woolway, R. Iestyn; Simpson, John H.

2017-08-01

ADCP and temperature chain measurements have been used to estimate the rate of energy input by wind stress to the water surface in the south basin of Windermere. The energy input from the atmosphere was found to increase markedly as the lake stratified in spring. The efficiency of energy transfer ( Eff), defined as the ratio of the rate of working in near-surface waters ( RW) to that above the lake surface ( P 10), increased from ˜0.0013 in vertically homogenous conditions to ˜0.0064 in the first 40 days of the stratified regime. A maximum value of Eff˜0.01 was observed when, with increasing stratification, the first mode internal seiche period decreased to match the diurnal wind period of 24 h. The increase in energy input, following the onset of stratification was reflected in enhancement of the mean depth-varying kinetic energy without a corresponding increase in wind forcing. Parallel estimates of energy dissipation in the bottom boundary layer, based on determination of the structure function show that it accounts for ˜15% of RW in stratified conditions. The evolution of stratification in the lake conforms to a heating stirring model which indicates that mixing accounts for ˜21% of RW. Taken together, these estimates of key energetic parameters point the way to the development of full energy budgets for lakes and shallow seas.

Characterization and modeling of the heat source

Energy Technology Data Exchange (ETDEWEB)

Glickstein, S.S.; Friedman, E.

1993-10-01

A description of the input energy source is basic to any numerical modeling formulation designed to predict the outcome of the welding process. The source is fundamental and unique to each joining process. The resultant output of any numerical model will be affected by the initial description of both the magnitude and distribution of the input energy of the heat source. Thus, calculated weld shape, residual stresses, weld distortion, cooling rates, metallurgical structure, material changes due to excessive temperatures and potential weld defects are all influenced by the initial characterization of the heat source. Understandings of both the physics and the mathematical formulation of these sources are essential for describing the input energy distribution. This section provides a brief review of the physical phenomena that influence the input energy distributions and discusses several different models of heat sources that have been used in simulating arc welding, high energy density welding and resistance welding processes. Both simplified and detailed models of the heat source are discussed.

Relations between the efficiency, power and dissipation for linear irreversible heat engine at maximum trade-off figure of merit

Science.gov (United States)

Iyyappan, I.; Ponmurugan, M.

2018-03-01

A trade of figure of merit (\\dotΩ ) criterion accounts the best compromise between the useful input energy and the lost input energy of the heat devices. When the heat engine is working at maximum \\dotΩ criterion its efficiency increases significantly from the efficiency at maximum power. We derive the general relations between the power, efficiency at maximum \\dotΩ criterion and minimum dissipation for the linear irreversible heat engine. The efficiency at maximum \\dotΩ criterion has the lower bound \

Effect of using ethanol and methanol on thermal performance of a closed loop pulsating heat pipe (CLPHP) with different filling ratios

Science.gov (United States)

Rahman, Md. Lutfor; Salsabil, Zaimaa; Yasmin, Nusrat; Nourin, Farah Nazifa; Ali, Mohammad

2016-07-01

This paper presents an experimental study of a closed loop Pulsating Heat Pipe (CLPHP) as the demand of smaller and effective heat transfer devices is increasing day by day. PHP is a two phase heat transfer device suited for heat transfer applications, especially suited for handling moderate to high heat fluxes in different applications. A copper made Pulsating Heat Pipe (PHP) of 250 mm length is used in this experimental work with 2 mm ID and 3 mm OD, closed end-to-end in 8 looped, evacuated and then partially filled with working fluids. The evaporation section is 50 mm, adiabatic section is 120 mm and condensation section is 80 mm. The performance characterization is done for two working fluids at Vertical (0°) orientations. The working fluids are Methanol and Ethanol and the filling ratios are 40%, 50%, 60% & 70% based on total volume, respectively. The results show that the influence of various parameters, the heat input flux, and different filling ratios on a heat transfer performance of CLPHP. Methanol shows better performance as working fluid in PHP than ethanol at present orientation for a wide range of heat inputs and can be used at high heat input conditions. Ethanol is better choice to be used in low heat input conditions.

Thermodynamic analysis of waste heat power generation system

International Nuclear Information System (INIS)

Guo, Jiangfeng; Xu, Mingtian; Cheng, Lin

2010-01-01

In the present work, a waste heat power generation system is analyzed based on the criteria with and without considering the heat/exergy loss to the environment. For the criteria without considering the heat/exergy loss to the environment, the first- and second-law efficiencies display different tendencies with the variations of some system parameters. When the heat/exergy loss to the environment is taken into consideration, the first and second law efficiencies display the same tendency. Thus, choosing the appropriate expressions for the performance criteria is crucial for the optimization design of the waste heat power generation system. It is found that there are two approaches to improving the system performance: one is to improve the heat/exergy input; the other is to enhance the heat-work conversion ability of the system. The former would deteriorate the environment if the heat-work conversion ability of the system remains unchanged; the latter could reduce the environmental impact but it's restricted by the heat/exergy input. Therefore, the optimal operation condition should be achieved at the trade-off between the heat/exergy input and the heat-work conversion ability of the system.

Transient turbulent heat transfer for heating of water in a short vertical tube

International Nuclear Information System (INIS)

Hata, Koichi; Kai, Naoto; Shirai, Yasuyuki; Masuzaki, Suguru

2011-01-01

The transient turbulent heat transfer coefficients in a short vertical Platinum test tube were systematically measured for the flow velocities (u=4.0 to 13.6 m/s), the inlet liquid temperatures (T in =296.93 to 304.81 K), the inlet pressures (P in =794.39 to 858.27 kPa) and the increasing heat inputs (Q 0 exp(t/τ), exponential periods, τ, of 18.6 ms to 25.7 s) by an experimental water loop comprised of a multistage canned-type circulation pump with high pump head. The Platinum test tubes of test tube inner diameters (d=3 and 6 mm), heated lengths (L=66.5 and 69.6 mm), effective lengths (L eff =56.7 and 59.2 mm), ratios of heated length to inner diameter (L/d=22.16 and 11.6), ratios of effective length to inner diameter (L eff /d=18.9 and 9.87) and wall thickness (δ=0.5 and 0.4 mm) with average surface roughness (Ra=0.40 and 0.45 μm) were used in this work. The surface heat fluxes between the two potential taps were given the difference between the heat generation rate per unit surface area and the rate of change of energy storage in the test tube obtained from the faired average temperature versus time curve. The heater inner surface temperature between the two potential taps was also obtained by solving the unsteady heat conduction equation in the test tube under the conditions of measured average temperature and heat generation rate per unit surface area of the test tube. The transient turbulent heat transfer data for Platinum test tubes were compared with the values calculated by authors' correlation for the steady state turbulent heat transfer. The influence of inner diameter (d), ratio of effective length to inner diameter (L eff /d), flow velocity (u) and exponential period (τ) on the transient turbulent heat transfer is investigated into details and the widely and precisely predictable correlation of the transient turbulent heat transfer for heating of water in a short vertical tube is given based on the experimental data and authors' studies for the

Transient turbulent heat transfer for heating of water in a short vertical tube

International Nuclear Information System (INIS)

Hata, Koichi; Kai, Naoto; Shirai, Yasuyuki; Masuzaki, Suguru

2011-01-01

The transient turbulent heat transfer coefficients in a short vertical Platinum test tube were systematically measured for the flow velocities (u=4.0 to 13.6 m/s), the inlet liquid temperatures (T in =296.93 to 304.81 K), the inlet pressures (P in =794.39 to 858.27 kPa) and the increasing heat inputs (Q 0 exp(t/τ), exponential periods, τ, of 18.6 ms to 25.7 s) by an experimental water loop comprised of a multistage canned-type circulation pump with high pump head. The Platinum test tubes of test tube inner diameters (d=3 and 6 mm), heated lengths (L=66.5 and 69.6 mm), effective lengths (L eff =56.7 and 59.2 mm), ratios of heated length to inner diameter (L/d=22.16 and 11.6), ratios of effective length to inner diameter (L eff /d=18.9 and 9.87) and wall thickness (δ=0.5 and 0.4 mm) with average surface roughness (Ra=0.40 and 0.45 μm) were used in this work. The surface heat fluxes between the two potential taps were given the difference between the heat generation rate per unit surface area and the rate of change of energy storage in the test tube obtained from the faired average temperature versus time curve. The heater inner surface temperature between the two potential taps was also obtained by solving the unsteady heat conduction equation in the test tube under the conditions of measured average temperature and heat generation rate per unit surface area of the test tube. The transient turbulent heat transfer data for Platinum test tubes were compared with the values calculated by authors' correlation for the steady state turbulent heat transfer. The influence of inner diameter (d), ratio of effective length to inner diameter (L eff /d), flow velocity (u) and exponential period (τ) on the transient turbulent heat transfer is investigated into details and the widely and precisely predictable correlation of the transient turbulent heat transfer for heating of water in a short vertical tube is given based on the experimental data and authors' studies for the

The effect of air velocity on heat stress at increased air temperature

DEFF Research Database (Denmark)

Bjerg, B.; Wang, Xiaoshuai; Zhang, Guoqiang

Increased air velocity is a frequently used method to reduce heat stress of farm animals housed in warm conditions. The main reason why the method works is that higher air velocity increases the convective heat release from the animals. Convective heat release from the animals is strongly related...... to the temperature difference between the surfaces of animals and the surrounding air, and this temperature difference declines when the air temperature approaches the animal body temperature. Consequently it can it by expected that the effect of air velocity decreases at increased air temperature. The literature...... on farm animals in warm conditions includes several thermal indices which incorporate the effect of air velocities. But, surprisingly none of them predicts a decreased influence of air velocity when the air temperature approaches the animal body temperature. This study reviewed published investigations...

Wildland Fire Induced Heating of Dome 375 Perma-Con®

Energy Technology Data Exchange (ETDEWEB)

Flores, Eugene Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-08-09

AET-1 was tasked by ADEM with determining the temperature rise in the drum contents of drums stored in the Dome 375 Perma-Con® at TA-54 given a wildland fire. The wildland fire causes radiative and convective heating on the Perma-Con® exterior. The wildland fire time histories for the radiative and convective heating environment were provided to AET-1 by EES-16. If the calculated temperature rise results in a drum content temperature over 40 °C, then ADEM desires a design solution to ensure the peak temperature remains below 40 °C. An axi-symmetric FE simulation was completed to determine the peak temperature of the contents of a drum stored in the Dome 375 Perma-Con® during a wildland fire event. Three wildland fire time histories for the radiative and convective heat transfer were provided by EES-16 and were inputs for the FE simulation. The maximum drum content temperature reached was found to be 110 °C while using inputs from the SiteG_2ms_4ign_wind_from_west.xlsx time history input and not including the SWB in the model. Including the SWB in the results in a peak drum content temperature of 61 °C for the SiteG_2ms_4ign_wind_from_west.xlsx inputs. EES-16 decided that by using fuel mitigation efforts, such as mowing the grass and shrubs near the Perma-Con® they could reduce the shrub/grass fuel loading near the Perma-Con® from 1.46 kg/m² to 0.146 kg/m² and by using a less conservative fuel loading for the debris field inside the Dome 375 perimeter, reducing it from 0.58 kg/m2 to 0.058 kg/m² in their model. They also greatly increased the resolution of their radiation model and increased the accuracy of their model’s required convergence value. Using this refined input the maximum drum content temperature was found to be 28 °C with no SWB present in the model. Additionally, this refined input model was modified to include worst case emissivity values for the concrete, drum and Perma-Con® interior, along with adding a

Analysis of Decentralized Control for Absorption Cycle Heat Pumps

DEFF Research Database (Denmark)

Vinther, Kasper; Just Nielsen, Rene; Nielsen, Kirsten Mølgaard

2015-01-01

Email Print Request Permissions This paper investigates decentralized control structures for absorption cycle heat pumps and a dynamic nonlinear model of a single-effect LiBr-water absorption system is used as case study. The model has four controllable inputs, which can be used to stabilize...... the operation of the heat pump under different load conditions. Different feasible input-output pairings are analyzed by computation of relative gain array matrices and scaled condition numbers, which indicate the best pairing choice and the potential of each input-output set. Further, it is possible...... to minimize the effect of cross couplings and improve stability with the right pairing of input and output. Simulation of selected candidate input-output pairings demonstrate that decentralized control can provide stable operation of the heat pump....

A self-adaptive thermal switch array for rapid temperature stabilization under various thermal power inputs

International Nuclear Information System (INIS)

Geng, Xiaobao; Patel, Pragnesh; Narain, Amitabh; Meng, Dennis Desheng

2011-01-01

A self-adaptive thermal switch array (TSA) based on actuation by low-melting-point alloy droplets is reported to stabilize the temperature of a heat-generating microelectromechanical system (MEMS) device at a predetermined range (i.e. the optimal working temperature of the device) with neither a control circuit nor electrical power consumption. When the temperature is below this range, the TSA stays off and works as a thermal insulator. Therefore, the MEMS device can quickly heat itself up to its optimal working temperature during startup. Once this temperature is reached, TSA is automatically turned on to increase the thermal conductance, working as an effective thermal spreader. As a result, the MEMS device tends to stay at its optimal working temperature without complex thermal management components and the associated parasitic power loss. A prototype TSA was fabricated and characterized to prove the concept. The stabilization temperatures under various power inputs have been studied both experimentally and theoretically. Under the increment of power input from 3.8 to 5.8 W, the temperature of the device increased only by 2.5 °C due to the stabilization effect of TSA

Accelerated life tests of specimen heat pipe from Communication Technology Satellite (CTS) project

Science.gov (United States)

Tower, L. K.; Kaufman, W. B.

1977-01-01

A gas-loaded variable conductance heat pipe of stainless steel with methanol working fluid identical to one now on the CTS satellite was life tested in the laboratory at accelerated conditions for 14 200 hours, equivalent to about 70 000 hours at flight conditions. The noncondensible gas inventory increased about 20 percent over the original charge. The observed gas increase is estimated to increase operating temperature by about 2.2 C, insufficient to harm the electronic gear cooled by the heat pipes in the satellite. Tests of maximum heat input against evaporator elevation agree well with the manufacturer's predictions.

Contrasting responses of urban and rural surface energy budgets to heat waves explain synergies between urban heat islands and heat waves

International Nuclear Information System (INIS)

Li, Dan; Sun, Ting; Liu, Maofeng; Yang, Long; Wang, Linlin; Gao, Zhiqiu

2015-01-01

Heat waves (HWs) are projected to become more frequent and last longer over most land areas in the late 21st century, which raises serious public health concerns. Urban residents face higher health risks due to synergies between HWs and urban heat islands (UHIs) (i.e., UHIs are higher under HW conditions). However, the responses of urban and rural surface energy budgets to HWs are still largely unknown. This study analyzes observations from two flux towers in Beijing, China and reveals significant differences between the responses of urban and rural (cropland) ecosystems to HWs. It is found that UHIs increase significantly during HWs, especially during the nighttime, implying synergies between HWs and UHIs. Results indicate that the urban site receives more incoming shortwave radiation and longwave radiation due to HWs as compared to the rural site, resulting in a larger radiative energy input into the urban surface energy budget. Changes in turbulent heat fluxes also diverge strongly for the urban site and the rural site: latent heat fluxes increase more significantly at the rural site due to abundant available water, while sensible heat fluxes and possibly heat storage increase more at the urban site. These comparisons suggest that the contrasting responses of urban and rural surface energy budgets to HWs are responsible for the synergies between HWs and UHIs. As a result, urban mitigation and adaption strategies such as the use of green roofs and white roofs are needed in order to mitigate the impact of these synergies. (letter)

Jupiter's Auroral Energy Input Observed by Hisaki/EXCEED and its Modulations by Io's Volcanic Activity

Science.gov (United States)

Tao, C.; Kimura, T.; Tsuchiya, F.; Murakami, G.; Yoshioka, K.; Kita, H.; Yamazaki, A.; Kasaba, Y.; Yoshikawa, I.; Fujimoto, M.

2016-12-01

Aurora is an important indicator representing the momentum transfer from the fast-rotating outer planet to the magnetosphere and the energy input into the atmosphere through the magnetosphere-ionosphere coupling. Long-term monitoring of Jupiter's northern aurora was achieved by the Extreme Ultraviolet (EUV) spectrometer called EXCEED (Extreme Ultraviolet Spectroscope for Exospheric Dynamics) onboard JAXA's Earth-orbiting planetary space telescope Hisaki until today after its launch in September 2013. We have proceeded the statistical survey of the Jupiter's auroral energy input into the upper atmosphere. The auroral electron energy is estimated using a hydrocarbon color ratio (CR) adopted for the wavelength range of EXCEED, and the emission power in the long wavelength range 138.5-144.8 nm is used as an indicator of total emitted power before hydrocarbon absorption and auroral electron energy flux. Temporal dynamic variation of the auroral intensity was detected when Io's volcanic activity and thus EUV emission from the Io plasma torus are enhanced in the early 2015. Average of the total input power over 80 days increases by 10% with sometimes sporadically more than a factor of 3 upto 7, while the CR indicates the auroral electron energy decrease by 20% during the volcanic event compared to the other period. This indicates much more increase in the current system and Joule heating which contributes heating of the upper atmosphere. We will discuss the impact of this event on the upper atmosphere and ionosphere.

A stydy on the heat transfer characteristics in the composite heat pipe as modeling turbine rotor

International Nuclear Information System (INIS)

Kwon, Sun Sok; Jang, Yeong Suc; Yoo, Byung Wook

1993-01-01

The purpose of this research is to study the characteristics of heat transfer in composite rotary heat pipe as modeled turbine rotating by a finite element analysis and experiment. Nu number, Re number, Pr number and dimensionless condensate layer thickness by thermal input and revolutions per minute were given as analysis factors. The comparison between calculated and experimental data showed similar tendency. Therefore the analysis method may be useful to predict the performance of composite heat pipe. The resistance on heat pipe showed the best effect of heat transfer by film condensation, by decreasing film condensation, the heat transfer rate from condenser was increased rapidly. The dimensionless condensate layer thickness according to Re number at given Pr number showed constant values, the dimensionless condensate layer thickness is proportionate to the square root of inverse of revolution number per minute. In this study Nu = A(δ(ω/ν) -1/2 Re B ) is used to the convection heat transfer coefficient and A = 0.963, B = 0.5025 were obtained as analysis predicts. (Author)

HEATING-7, Multidimensional Finite-Difference Heat Conduction Analysis

International Nuclear Information System (INIS)

2000-01-01

1 - Description of program or function: HEATING 7.2i and 7.3 are the most recent developments in a series of heat-transfer codes and obsolete all previous versions distributed by RSICC as SCA-1/HEATING5 and PSR-199/HEATING 6. Note that Unix and PC versions of HEATING7 are available in the CCC-545/SCALE 4.4 package. HEATING can solve steady-state and/or transient heat conduction problems in one-, two-, or three-dimensional Cartesian, cylindrical, or spherical coordinates. A model may include multiple materials, and the thermal conductivity, density, and specific heat of each material may be both time- and temperature-dependent. The thermal conductivity may also be anisotropic. Materials may undergo change of phase. Thermal properties of materials may be input or may be extracted from a material properties library. Heat- generation rates may be dependent on time, temperature, and position, and boundary temperatures may be time- and position-dependent. The boundary conditions, which may be surface-to-environment or surface-to-surface, may be specified temperatures or any combination of prescribed heat flux, forced convection, natural convection, and radiation. The boundary condition parameters may be time- and/or temperature-dependent. General gray body radiation problems may be modeled with user-defined factors for radiant exchange. The mesh spacing may be variable along each axis. HEATING uses a run-time memory allocation scheme to avoid having to recompile to match memory requirements for each specific problem. HEATING utilizes free-form input. In June 1997 HEATING 7.3 was added to the HEATING 7.2i packages, and the Unix and PC versions of both 7.2i and 7.3 were merged into one package. HEATING 7.3 is being released as a beta-test version; therefore, it does not entirely replace HEATING 7.2i. There is no published documentation for HEATING 7.3; but a listing of input specifications, which reflects changes for 7.3, is included in the PSR-199 documentation. For 3-D

Optimal design of tests for heat exchanger fouling identification

International Nuclear Information System (INIS)

Palmer, Kyle A.; Hale, William T.; Such, Kyle D.; Shea, Brian R.; Bollas, George M.

2016-01-01

Highlights: • Built-in test design that optimizes the information extractable from the said test. • Method minimizes the covariance of a fault with system uncertainty. • Method applied for the identification and quantification of heat exchanger fouling. • Heat exchanger fouling is identifiable despite the uncertainty in inputs and states. - Graphical Abstract: - Abstract: Particulate fouling in plate fin heat exchangers of aircraft environmental control systems is a recurring issue in environments rich in foreign object debris. Heat exchanger fouling detection, in terms of quantification of its severity, is critical for aircraft maintenance scheduling and safe operation. In this work, we focus on methods for offline fouling detection during aircraft ground handling, where the allowable variability range of admissible inputs is wider. We explore methods of optimal experimental design to estimate heat exchanger inputs and input trajectories that maximize the identifiability of fouling. In particular, we present a methodology in which D-optimality is used as a criterion for statistically significant inference of heat exchanger fouling in uncertain environments. The optimal tests are designed on the basis of a heat exchanger model of the inherent mass, energy and momentum balances, validated against literature data. The model is then used to infer sensitivities of the heat exchanger outputs with respect to fouling metrics and maximize them by manipulating input trajectories; thus enhancing the accuracy in quantifying the fouling extent. The proposed methodology is evaluated with statistical indices of the confidence in estimating thermal fouling resistance at uncertain operating conditions, explored in a series of case studies.

Evaluation of Energy Efficiency Performance of Heated Windows

Science.gov (United States)

Jammulamadaka, Hari Swarup

The study about the evaluation of the performance of the heated windows was funded by the WVU Research Office as a technical assistance award at the 2014 TransTech Energy Business Development Conference to the Green Heated Glass company/project owned by Frank Dlubak. The award supports a WVU researcher to conduct a project important for commercialization. This project was awarded to the WVU Industrial Assessment Center in 2015. The current study attempted to evaluate the performance of the heated windows by developing an experimental setup to test the window at various temperatures by varying the current input to the window. The heated double pane window was installed in an insulated box. A temperature gradient was developed across the window by cooling one side of the window using gel based ice packs. The other face of the window was heated by passing current at different wattages through the window. The temperature of the inside and outside panes, current and voltage input, room and box temperature were recorded, and used to calculate the apparent R-value of the window when not being heated vs when being heated. It has been concluded from the study that the heated double pane window is more effective in reducing heat losses by as much as 50% than a non-heated double pane window, if the window temperature is maintained close to the room temperature. If the temperature of the window is much higher than the room temperature, the losses through the window appear to increase beyond that of a non-heated counterpart. The issues encountered during the current round of experiments are noted, and recommendations provided for future studies.

Numerical Simulation of the Heat Transfer Behavior of a Zigzag Plate Containing a Phase Change Material for Combustion Heat Recovery and Power Generation

Directory of Open Access Journals (Sweden)

Peilun Wang

2016-01-01

Full Text Available This study presents a numerical analysis of the melting process of phase change materials (PCMs within a latent heat thermal energy storage (LHTES system employing zigzag plate. The numerical model used NaCl-MgCl2 mixture as PCMs and hot air as heat transfer fluid (HTF. An experimental system was built to validate the model, and the experimental data agrees reasonably well with the simulation results. The simulation results revealed the effects of the Reynolds and Stefan numbers and the surface topography of the zigzag plate on the charging process. Besides, the effect of the relationship between Reynolds and Stefan numbers on the charging process under a new boundary condition employing a fixed input power was studied. It is found that by modifying the shape of the zigzag plate surface it is feasible to enhance the heat transfer of the LHTES unit remarkably. The melting rate of PCMs increases with the value of Ste or Re numbers with only one of them changing; however, the melting rate of PCMs decreases with the increasing Ste (or decreasing Re in a fixed input power condition.

Increased nitrogen input enhances Kandelia obovata seedling growth in the presence of invasive Spartina alterniflora in subtropical regions of China.

Science.gov (United States)

Cui, Xiaowei; Song, Weimin; Feng, Jianxiang; Jia, Dai; Guo, Jiemin; Wang, Zhonglei; Wu, Hao; Qi, Fei; Liang, Jie; Lin, Guanghui

2017-01-01

Mangroves in China are severely affected by the rapid invasion of the non-native species Spartina alterniflora Although many studies have addressed the possible impacts of S. alterniflora on the performance of mangrove seedlings, how excessive nitrogen (N) input due to eutrophication affects the interactions between mangrove species and S. alterniflora remains unknown. Here, we report the results from a mesocosm experiment using seedlings of the native mangrove species Kandelia obovata and the exotic S. alterniflora grown in monoculture and mixed culture under no nitrogen addition and nitrogen (N) addition treatments for 18 months. Without N addition, the presence of S. alterniflora inhibited the growth of K. obovata seedlings. Excessive N addition significantly increased the growth rate of K. obovata in both cultures. However, the positive and significantly increasing relative interaction intensity index under excessive N input suggested that the invasion of S. alterniflora could favour the growth of K. obovata under eutrophication conditions. Our results imply that excessive N input in southeastern China can increase the competitive ability of mangrove seedlings against invasive S. alterniflora. © 2017 The Author(s).

Hydrologic connectivity to streams increases nitrogen and phosphorus inputs and cycling in soils of created and natural floodplain wetlands

Science.gov (United States)

Wolf, Kristin L.; Noe, Gregory; Ahn, Changwoo

2013-01-01

Greater connectivity to stream surface water may result in greater inputs of allochthonous nutrients that could stimulate internal nitrogen (N) and phosphorus (P) cycling in natural, restored, and created riparian wetlands. This study investigated the effects of hydrologic connectivity to stream water on soil nutrient fluxes in plots (n = 20) located among four created and two natural freshwater wetlands of varying hydrology in the Piedmont physiographic province of Virginia. Surface water was slightly deeper; hydrologic inputs of sediment, sediment-N, and ammonium were greater; and soil net ammonification, N mineralization, and N turnover were greater in plots with stream water classified as their primary water source compared with plots with precipitation or groundwater as their primary water source. Soil water-filled pore space, inputs of nitrate, and soil net nitrification, P mineralization, and denitrification enzyme activity (DEA) were similar among plots. Soil ammonification, N mineralization, and N turnover rates increased with the loading rate of ammonium to the soil surface. Phosphorus mineralization and ammonification also increased with sedimentation and sediment-N loading rate. Nitrification flux and DEA were positively associated in these wetlands. In conclusion, hydrologic connectivity to stream water increased allochthonous inputs that stimulated soil N and P cycling and that likely led to greater retention of sediment and nutrients in created and natural wetlands. Our findings suggest that wetland creation and restoration projects should be designed to allow connectivity with stream water if the goal is to optimize the function of water quality improvement in a watershed.

Heat Transfer Model for Hot Air Balloons

Science.gov (United States)

Llado-Gambin, Adriana

A heat transfer model and analysis for hot air balloons is presented in this work, backed with a flow simulation using SolidWorks. The objective is to understand the major heat losses in the balloon and to identify the parameters that affect most its flight performance. Results show that more than 70% of the heat losses are due to the emitted radiation from the balloon envelope and that convection losses represent around 20% of the total. A simulated heating source is also included in the modeling based on typical thermal input from a balloon propane burner. The burner duty cycle to keep a constant altitude can vary from 10% to 28% depending on the atmospheric conditions, and the ambient temperature is the parameter that most affects the total thermal input needed. The simulation and analysis also predict that the gas temperature inside the balloon decreases at a rate of -0.25 K/s when there is no burner activity, and it increases at a rate of +1 K/s when the balloon pilot operates the burner. The results were compared to actual flight data and they show very good agreement indicating that the major physical processes responsible for balloon performance aloft are accurately captured in the simulation.

Experimental investigation of pulsating heat pipe performance with regard to fuel cell cooling application

International Nuclear Information System (INIS)

Clement, Jason; Wang Xia

2013-01-01

A pulsating heat pipe (PHP) is a closed loop, passive heat transfer device. Its operation depends on the phase change of a working fluid within the loop. Design and performance testing of a pulsating heat pipe was conducted under conditions to simulate heat dissipation requirements of a proton exchange membrane (PEM) fuel cell stack. Integration of pulsating heat pipes within bipolar plates of the stack would eliminate the need for ancillary cooling equipment, thus also reducing parasitic losses and increasing energy output. The PHP under investigation, having dimensions of 46.80 cm long and 14.70 cm wide, was constructed from 0.3175 cm copper tube. Heat pipes effectiveness was found to be dependent upon several factors such as energy input, types of working fluid and its filling ratio. Power inputs to the evaporator side of the pulsating heat pipe varied from 80 to 180 W. Working fluids tested included acetone, methanol, and deionized water. Filling ratios between 30 and 70 percent of the total working volume were also examined. Methanol outperformed other fluids tested; with a 45 percent fluid fill ratio and a 120 W power input, the apparatus took the shortest time to reach steady state and had one of the smallest steady state temperature differences. The various conditions studied were chosen to assess the heat pipe's potential as cooling media for PEM fuel cells. - Highlights: ► Methanol as a working fluid outperformed both acetone and water in a pulsating heat pipe. ► Performance for the PHP peaked with methanol and a fill ratio of 45 percent fluid to total volume. ► A smaller resistance was associated with a higher power input to the system.

Winter-regime surface heat loss from heated streams

International Nuclear Information System (INIS)

Paily, P.P.; Macagno, E.O.; Kennedy, J.F.

1974-01-01

Evaluation of the rate of surface heat exchange between the water and air is a significant factor in any study of the thermal response of heated streams to heat inputs. Existing methods to determine the amount of heat transfer across the water surface are surveyed, and the different formulas developed for determining the heat exchange components are compiled. Heat-transfer models that have been proposed in the literature are reviewed, and a new linearized model for determining the rate of surface heat exchange is proposed. Generalized relations between the major climatological factors and the coefficients of the linearized heat-loss rate are established by multiple-regression analysis. The analysis is limited to cold-period conditions, in the sense that air temperatures below the freezing point of water only are considered in developing the regression equations. A computer program, using FORTRAN, is presented which enables the computation of the coefficients appearing in the linearized heat-loss rate for all combinations of the various climatological factors

Forced convection heat transfer in He II

International Nuclear Information System (INIS)

Kashani, A.

1986-01-01

An investigation of forced convection heat transfer in He II is conducted. The study includes both experimental and theoretical treatments of the problem. The experiment consists of a hydraulic pump and a copper flow tube, 3 mm in ID and 2m long. The system allows measurements of one-dimensional heat and mass transfer in He II. The heat transfer experiments are performed by applying heat at the midpoint along the length of the flow tube. Two modes of heat input are employed, i.e., step function heat input and square pulse heat input. The heat transfer results are discussed in terms of temperature distribution in the tube. The experimental temperature profiles are compared with numerical solutions of an analytical model developed from the He II energy equation. The bath temperature is set at three different values of 1.65, 1.80, and 1.95 K. The He II flow velocity is varied up to 90 cm/s. Pressure is monitored at each end of the flow tube, and the He II pressure drop is obtained for different flow velocities. Results indicate that He II heat transfer by forced convention is considerably higher than that by internal convection. The theoretical model is in close agreement with the experiment. He II pressure drop and friction factor are very similar to those of an ordinary fluid

Mild electrical stimulation with heat stimulation increase heat shock protein 70 in articular chondrocyte.

Science.gov (United States)

Hiraoka, Nobuyuki; Arai, Yuji; Takahashi, Kenji A; Mazda, Osam; Kishida, Tsunao; Honjo, Kuniaki; Tsuchida, Shinji; Inoue, Hiroaki; Morino, Saori; Suico, Mary Ann; Kai, Hirofumi; Kubo, Toshikazu

2013-06-01

The objective of this study is to investigate the effects of mild electrical stimulation (MES) and heat stress (HS) on heat shock protein 70 (HSP70), that protects chondrocytes and enhances cartilage matrix metabolism, in chondrocyte and articular cartilage. Rabbit articular chondrocytes were treated with MES and/or HS. The safeness was assessed by LDH assay and morphology. HSP70 protein, ubiquitinated proteins and HSP70 mRNA were examined by Western blotting and real-time PCR. Rat knee joints were treated with MES and/or HS. HSP70 protein, ubiquitinated proteins, HSP70 mRNA and proteoglycan core protein (PG) mRNA in articular cartilage were investigated. In vitro, HS increased HSP70 mRNA and HSP70 protein. MES augmented ubiquitinated protein and HSP70 protein, but not HSP70 mRNA. MES + HS raised HSP70 mRNA and ubiquitinated protein, and significantly increased HSP70 protein. In vivo, HS and MES + HS treatment augmented HSP70 mRNA. HS modestly augmented HSP70 protein. MES + HS significantly increased HSP70 protein and ubiquitinated proteins. PG mRNA was markedly raised by MES + HS. This study demonstrated that MES, in combination with HS, increases HSP70 protein in chondrocytes and articular cartilage, and promotes cartilage matrix metabolism in articular cartilage. MES in combination with HS can be a novel physical therapy for osteoarthritis by inducing HSP70 in articular cartilage. Copyright © 2013 Orthopaedic Research Society.

Experimentally-determined external heat loss of automotive gas turbine engine

Science.gov (United States)

Meng, P. R.; Wulf, R. F.

1975-01-01

An external heat balance was conducted on a 150 HP two-shaft automotive gas turbine engine. The engine was enclosed in a calorimeter box and the temperature change of cooling air passing through the box was measured. Cooling airflow ranges of 1.6 to 2.1 lb-per-second and 0.8 to 1.1 lb-per-second were used. The engine housing heat loss increased as the cooling airflow through the calorimeter box was increased, as would be the case in a moving automobile. The heat balance between the total energy input and the sum of shaft power output and various losses compared within 30 percent at engine idle speeds and within 7 percent at full power.

Estimation and optimization of heat transfer and overall presure drop for a shell and tube heat exchanger

Energy Technology Data Exchange (ETDEWEB)

Rao, Bala Bhaskara [Dept. of Mechanical Engineering, SISTAM College, JNTU, Kakinada (India); Raju, V. Ramachandra [Dept. of Mechanical Engineering, JNTU, Kakinada (India); Deepak, B. B V. L. [Dept. of Industrial Design, National Institute of Technology, Rourkela (India)

2017-01-15

Most thermal/chemical industries are equipped with heat exchangers to enhance thermal efficiency. The performance of heat exchangers highly depends on design modifications in the tube side, such as the cross-sectional area, orientation, and baffle cut of the tube. However, these parameters do not exhibit a specific relation to determining the optimum design condition for shell and tube heat exchangers with a maximum heat transfer rate and reduced pressure drops. Accordingly, experimental and numerical simulations are performed for a heat exchanger with varying tube geometries. The heat exchanger considered in this investigation is a single-shell, multiple-pass device. A Generalized regression neural network (GRNN) is applied to generate a relation among the input and output process parameters for the experimental data sets. Then, an Artificial immune system (AIS) is used with GRNN to obtain optimized input parameters. Lastly, results are presented for the developed hybrid GRNN-AIS approach.

Procedures for selecting and buying district heating equipment. Sofia district heating. Final report

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-11-01

The aim of this Final Report, prepared for the project `Procedures for Selecting and Buying DistRict Heating Equipment - Sofia District Heating Company`, is to establish an overview of the activities accomplished, the outputs delivered and the general experience gained as a result of the project. The main objective of the project is to enable Sofia District Heating Company to prepare specifications and tender documents, identify possible suppliers, evaluate offers, etc. in connection with purchase of district heating equipment. This objective has been reached by using rehabilitation of sub-stations as an example requested by Sofia DH. The project was originally planned to be finalized end of 1995, but due to the extensions of the scope of work, the project has been prolonged until end 1997. The following main activities were accomplished: Preparation of a detailed work plan; Collection of background information; Discussion and advice about technical specifications and tender documents for sub-station rehabilitation; Input to terms of reference for a master plan study; Input to technical specification for heat meters; Collection of ideas for topics and examples related to dissemination of information to consumers about matters related to district heating consumption. (EG)

Hydrologic connectivity to streams increases nitrogen and phosphorus inputs and cycling in soils of created and natural floodplain wetlands.

Science.gov (United States)

Wolf, Kristin L; Noe, Gregory B; Ahn, Changwoo

2013-07-01

Greater connectivity to stream surface water may result in greater inputs of allochthonous nutrients that could stimulate internal nitrogen (N) and phosphorus (P) cycling in natural, restored, and created riparian wetlands. This study investigated the effects of hydrologic connectivity to stream water on soil nutrient fluxes in plots ( = 20) located among four created and two natural freshwater wetlands of varying hydrology in the Piedmont physiographic province of Virginia. Surface water was slightly deeper; hydrologic inputs of sediment, sediment-N, and ammonium were greater; and soil net ammonification, N mineralization, and N turnover were greater in plots with stream water classified as their primary water source compared with plots with precipitation or groundwater as their primary water source. Soil water-filled pore space, inputs of nitrate, and soil net nitrification, P mineralization, and denitrification enzyme activity (DEA) were similar among plots. Soil ammonification, N mineralization, and N turnover rates increased with the loading rate of ammonium to the soil surface. Phosphorus mineralization and ammonification also increased with sedimentation and sediment-N loading rate. Nitrification flux and DEA were positively associated in these wetlands. In conclusion, hydrologic connectivity to stream water increased allochthonous inputs that stimulated soil N and P cycling and that likely led to greater retention of sediment and nutrients in created and natural wetlands. Our findings suggest that wetland creation and restoration projects should be designed to allow connectivity with stream water if the goal is to optimize the function of water quality improvement in a watershed. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Socio-economic effects and benefits of biofuels in power and heat generation

International Nuclear Information System (INIS)

Turkki, J.

1999-10-01

This report studies the socioeconomic effects and benefits of domestic fuels - peat and wood and agricultural energy plants also - in power and heat generation. For evaluation of the employment and income effects, it compares the costs of domestic as well as imported fuels as regards to production, transportation and power stations by looking especially at the direct labour input and inputs in terms of intermediate products and investment. Their indirect employment effects and allocation to domestic factor income and imports are introduced by means of an input-output model. The net changes in the disposable incomes of local households, firms and municipalities, the government and other are derived from factor incomes by means of income redistribution. If in heat generation 15 MW oil heating plant is replaced by a peat heating plant, the annual local employment increases by 8 man years. If the fuel used is wood, employment increases by 9 man-years. The disposable income of the local economy rises annually about FIM 0,8 million with the peat alternative and FIM 0,9 million with the wood alternative. Although with the domestic fuel alternatives the income tax revenue grows and the unemployment security payments decrease, the loss of the high fuel taxes collected on oil means however, that the government is netloser by FIM 0,8-1,4 million annually. The total annual import bill decreases both with peat and wood by FIM 2,5 million respectively. Calculated by a small-sized 3/9 MW cogeneration station, which in heat generation replaces oil heating plants and in power generation replaces coal condensation power, the annual local employment effect is 11 man-years with peat and 12 with food fuel. The local economy gain an annual net income of FIM 0,8-0,9 million. The net increase of the government is FIM 0,1 million annually. With the wood alternative the government is a net looser by FIM 0,2 million. The annual import bill decreases by FIM 2,3-2,5 million. (orig.)

Heating-insensitive scale increase caused by convective precipitation

Science.gov (United States)

Haerter, Jan; Moseley, Christopher; Berg, Peter

2017-04-01

The origin of intense convective extremes and their unusual temperature dependence has recently challenged traditional thermodynamic arguments, based on the Clausius-Clapeyron relation. In a sequence of studies (Lenderink and v. Mejgaard, Nat Geosc, 2008; Berg, Haerter, Moseley, Nat Geosc, 2013; and Moseley, Hohenegger, Berg, Haerter, Nat Geosc, 2016) the argument of convective-type precipitation overcoming the 7%/K increase in extremes by dynamical, rather than thermodynamic, processes has been promoted. How can the role of dynamical processes be approached for precipitating convective cloud? One-phase, non-precipitating Rayleigh-Bénard convection is a classical problem in complex systems science. When a fluid between two horizontal plates is sufficiently heated from below, convective rolls spontaneously form. In shallow, non-precipitating atmospheric convection, rolls are also known to form under specific conditions, with horizontal scales roughly proportional to the boundary layer height. Here we explore within idealized large-eddy simulations, how the scale of convection is modified, when precipitation sets in and intensifies in the course of diurnal solar heating. Before onset of precipitation, Bénard cells with relatively constant diameter form, roughly on the scale of the atmospheric boundary layer. We find that the onset of precipitation then signals an approximately linear (in time) increase in horizontal scale. This scale increase progresses at a speed which is rather insensitive to changes in surface temperature or changes in the rate at which boundary conditions change, hinting at spatial characteristics, rather than temperature, as a possible control on spatial scales of convection. When exploring the depth of spatial correlations, we find that precipitation onset causes a sudden disruption of order and a subsequent complete disintegration of organization —until precipitation eventually ceases. Returning to the initial question of convective

Preparation and documentation of a CATHENA input file for Darlington NGS

International Nuclear Information System (INIS)

1989-03-01

A CATHENA input model has been developed and documented for the heat transport system of the Darlington Nuclear Generating Station. CATHENA, an advanced two-fluid thermalhydraulic computer code, has been designed for analysis of postulated loss-of-coolant accidents (LOCA) and upset conditions in the CANDU system. This report describes the Darlington input model (or idealization), and gives representative results for a simulation of a small break at an inlet header

Historic and future increase in the global land area affected by monthly heat extremes

International Nuclear Information System (INIS)

Coumou, Dim; Robinson, Alexander

2013-01-01

Climatic warming of about 0.5 ° C in the global mean since the 1970s has strongly increased the occurrence-probability of heat extremes on monthly to seasonal time scales. For the 21st century, climate models predict more substantial warming. Here we show that the multi-model mean of the CMIP5 (Coupled Model Intercomparison Project) climate models accurately reproduces the evolution over time and spatial patterns of the historically observed increase in monthly heat extremes. For the near-term (i.e., by 2040), the models predict a robust, several-fold increase in the frequency of such heat extremes, irrespective of the emission scenario. However, mitigation can strongly reduce the number of heat extremes by the second half of the 21st century. Unmitigated climate change causes most (>50%) continental regions to move to a new climatic regime with the coldest summer months by the end of the century substantially hotter than the hottest experienced today. We show that the land fraction experiencing extreme heat as a function of global mean temperature follows a simple cumulative distribution function, which depends only on natural variability and the level of spatial heterogeneity in the warming. (letter)

A one-dimensional heat transfer model for parallel-plate thermoacoustic heat exchangers.

Science.gov (United States)

de Jong, J A; Wijnant, Y H; de Boer, A

2014-03-01

A one-dimensional (1D) laminar oscillating flow heat transfer model is derived and applied to parallel-plate thermoacoustic heat exchangers. The model can be used to estimate the heat transfer from the solid wall to the acoustic medium, which is required for the heat input/output of thermoacoustic systems. The model is implementable in existing (quasi-)1D thermoacoustic codes, such as DeltaEC. Examples of generated results show good agreement with literature results. The model allows for arbitrary wave phasing; however, it is shown that the wave phasing does not significantly influence the heat transfer.

Development, validation and application of a fixed district heating model structure that requires small amounts of input data

International Nuclear Information System (INIS)

Aberg, Magnus; Widén, Joakim

2013-01-01

Highlights: • A fixed model structure for cost-optimisaton studies of DH systems is developed. • A method for approximating heat demands using outdoor temperature data is developed. • Six different Swedish district heating systems are modelled and studied. • The impact of heat demand change on heat and electricity production is examined. • Reduced heat demand leads to less use of fossil fuels and biomass in the modelled systems. - Abstract: Reducing the energy use of buildings is an important part in reaching the European energy efficiency targets. Consequently, local energy systems need to adapt to a lower demand for heating. A 90% of Swedish multi-family residential buildings use district heating (DH) produced in Sweden’s over 400 DH systems, which use different heat production technologies and fuels. DH system modelling results obtained until now are mostly for particular DH systems and cannot be easily generalised. Here, a fixed model structure (FMS) based on linear programming for cost-optimisaton studies of DH systems is developed requiring only general DH system information. A method for approximating heat demands based on local outdoor temperature data is also developed. A scenario is studied where the FMS is applied to six Swedish DH systems and heat demands are reduced due to energy efficiency improvements in buildings. The results show that the FMS is a useful tool for DH system optimisation studies and that building energy efficiency improvements lead to reduced use of fossil fuels and biomass in DH systems. Also, the share of CHP in the production mix is increased in five of the six DH systems when the heat demand is reduced

Geothermal source heat pump performance for a greenhouse heating system: an experimental study

Directory of Open Access Journals (Sweden)

Alexandros Sotirios Anifantis

2016-09-01

Full Text Available Greenhouses play a significant function in the modern agriculture economy even if require great amount of energy for heating systems. An interesting solution to alleviate the energy costs and environmental problems may be represented by the use of geothermal energy. The aim of this paper, based on measured experimental data, such as the inside greenhouse temperature and the heat pump performance (input and output temperatures of the working fluid, electric consumption, was the evaluation of the suitability of low enthalpy geothermal heat sources for agricultural needs such as greenhouses heating. The study was carried out at the experimental farm of the University of Bari, where a greenhouse was arranged with a heating system connected to a ground-source heat pump (GSHP, which had to cover the thermal energy request. The experimental results of this survey highlight the capability of the geothermal heat source to ensue thermal conditions suitable for cultivation in greenhouses even if the compressor inside the heat pump have operated continuously in a fluctuating state without ever reaching the steady condition. Probably, to increase the performance of the heat pump and then its coefficient of performance within GSHP systems for heating greenhouses, it is important to analyse and maximise the power conductivity of the greenhouse heating system, before to design an expensive borehole ground exchanger. Nevertheless, according to the experimental data obtained, the GSHP systems are effective, efficient and environmental friendly and may be useful to supply the heating energy demand of greenhouses.

Change in algal symbiont communities after bleaching, not prior heat exposure, increases heat tolerance of reef corals.

Science.gov (United States)

Silverstein, Rachel N; Cunning, Ross; Baker, Andrew C

2015-01-01

Mutualistic organisms can be particularly susceptible to climate change stress, as their survivorship is often limited by the most vulnerable partner. However, symbiotic plasticity can also help organisms in changing environments by expanding their realized niche space. Coral-algal (Symbiodinium spp.) symbiosis exemplifies this dichotomy: the partnership is highly susceptible to 'bleaching' (stress-induced symbiosis breakdown), but stress-tolerant symbionts can also sometimes mitigate bleaching. Here, we investigate the role of diverse and mutable symbiotic partnerships in increasing corals' ability to thrive in high temperature conditions. We conducted repeat bleaching and recovery experiments on the coral Montastraea cavernosa, and used quantitative PCR and chlorophyll fluorometry to assess the structure and function of Symbiodinium communities within coral hosts. During an initial heat exposure (32 °C for 10 days), corals hosting only stress-sensitive symbionts (Symbiodinium C3) bleached, but recovered (at either 24 °C or 29 °C) with predominantly (>90%) stress-tolerant symbionts (Symbiodinium D1a), which were not detected before bleaching (either due to absence or extreme low abundance). When a second heat stress (also 32 °C for 10 days) was applied 3 months later, corals that previously bleached and were now dominated by D1a Symbiodinium experienced less photodamage and symbiont loss compared to control corals that had not been previously bleached, and were therefore still dominated by Symbiodinium C3. Additional corals that were initially bleached without heat by a herbicide (DCMU, at 24 °C) also recovered predominantly with D1a symbionts, and similarly lost fewer symbionts during subsequent thermal stress. Increased thermotolerance was also not observed in C3-dominated corals that were acclimated for 3 months to warmer temperatures (29 °C) before heat stress. These findings indicate that increased thermotolerance post-bleaching resulted from

Design of an isopropanol–acetone–hydrogen chemical heat pump with exothermic reactors in series

International Nuclear Information System (INIS)

Xu, Min; Duan, Yanjun; Xin, Fang; Huai, Xiulan; Li, Xunfeng

2014-01-01

The isopropanol–acetone–hydrogen chemical heat pump system with a series of exothermic reactors in which the reaction temperatures decrease successively is proposed. This system shows the better energy performances as compared with the traditional system with a single exothermic reactor, especially when the higher upgraded temperature is need. At the same amounts of the heat released, the work input of the compressor and the heater are both reduced notably. The results indicate that the advantages of the IAH-CHP system with exothermic reactors in series are obvious. - Highlights: • We propose the IAH-CHP system with exothermic reactors in series. • The COP and exergy efficiency of the system increase by 7.6% and 10.3% respectively. • The work input of the system is reduced notably at the same quantity of heat released

Heat-stress increase under climate change twice as large in cities as in rural areas

Science.gov (United States)

Wouters, Hendrik; De Ridder, Koen; Poelmans, Lien; Willems, Patrick; Brouwers, Johan; Hosseinzadehtalaei, Parisa; Tabari, Hossein; Vanden Broucke, Sam; van Lipzig, Nicole P. M.; Demuzere, Matthias

2017-04-01

Urban areas, being warmer than their surroundings, are particularly vulnerable to global warming and associated increases in extreme temperatures. Yet ensemble climate-model projections are generally performed on a scale that is too coarse to represent the evolution of temperatures in cities. Here, for the first time, we combine a 35-year convection-permitting climate model integrations with information from an ensemble of general circulation models to assess heat stress in a typical densely populated mid-latitude maritime region. We show that the heat-stress increase for the mid-21st century is twice as large in cities compared to their surrounding rural areas. The exacerbation is driven by the urban heat island itself, its concurrence with heatwaves, and urban expansion. Cities experience a heat-stress multiplication by a factor 1.4 and 15 depending on the scenario. Remarkably, the future heat-stress surpasses everywhere the urban hot spots of today. Our novel insights exemplify the need to combine information from climate models, acting on different scales, for climate-change risk assessment in heterogeneous regions. Moreover, these results highlight the necessity for adaptation to increasing heat stress, especially in urban areas.

Experimental investigation on a pulsating heat pipe with hydrogen

International Nuclear Information System (INIS)

Deng, H R; Liu, Y M; Ma, R F; Han, D Y; Gan, Z H; Pfotenhauer, J M

2015-01-01

The pulsating heat pipe (PHP) has been increasingly studied in cryogenic application, for its high transfer coefficient and quick response. Compared with Nb 3 Sn and NbTi, MgB 2 whose critical transformation temperature is 39 K, is expected to replace some high-temperature superconducting materials at 25 K. In order to cool MgB 2 , this paper designs a Hydrogen Pulsating Heat Pipe, which allows a study of applied heat, filling ratio, turn number, inclination angle and length of adiabatic section on the thermal performance of the PHP. The thermal performance of the hydrogen PHP is investigated for filling ratios of 35%, 51%, 70% at different heat inputs, and provides information regarding the starting process is received at three filling ratios. (paper)

Investigation of the effect of pressure increasing in condensing heat-exchanger

Science.gov (United States)

Murmanskii, I. B.; Aronson, K. E.; Brodov, Yu M.; Galperin, L. G.; Ryabchikov, A. Yu.; Brezgin, D. V.

2017-11-01

The effect of pressure increase was observed in steam condensation in the intermediate coolers of multistage steam ejector. Steam pressure increase for ejector cooler amounts up to 1.5 kPa in the first ejector stage, 5 kPa in the second and 7 kPa in the third one. Pressure ratios are equal to 2.0, 1.3 and 1.1 respectively. As a rule steam velocities at the cooler inlets do not exceed 40…100 m/s and are subsonic in all regimes. The report presents a computational model that describes the effect of pressure increase in the cooler. The steam entering the heat exchanger tears the drops from the condensate film flowing down vertical tubes. At the inlet of heat exchanger the steam flow capturing condensate droplets forms a steam-water mixture in which the sound velocity is significantly reduced. If the flow rate of steam-water mixture in heat exchanger is greater than the sound velocity, there occurs a pressure shock in the wet steam. On the basis of the equations of mass, momentum and energy conservation the authors derived the expressions for calculation of steam flow dryness degree before and after the shock. The model assumes that droplet velocity is close to the velocity of the steam phase (slipping is absent); drops do not come into thermal interaction with the steam phase; liquid phase specific volume compared to the volume of steam is neglected; pressure shock is calculated taking into account the gas-dynamic flow resistance of the tube bundle. It is also assumed that the temperature of steam after the shock is equal to the saturation temperature. The calculations have shown that the rise of steam pressure and temperature in the shock results in dryness degree increase. For calculated flow parameters the velocity value before the shock is greater than the sound velocity. Thus, on the basis of generally accepted physics knowledge the computational model has been formulated for the effect of steam pressure rise in the condensing heat exchanger.

Relationship between fatigue of generation II image intensifier and input illumination

Science.gov (United States)

Chen, Qingyou

1995-09-01

If there is fatigue for an image intesifier, then it has an effect on the imaging property of the night vision system. In this paper, using the principle of Joule Heat, we derive a mathematical formula for the generated heat of semiconductor photocathode. We describe the relationship among the various parameters in the formula. We also discuss reasons for the fatigue of Generation II image intensifier caused by bigger input illumination.

Optimization of operating parameters of ground source heat pump system for space heating and cooling by Taguchi method and utility concept

International Nuclear Information System (INIS)

Sivasakthivel, T.; Murugesan, K.; Thomas, H.R.

2014-01-01

Highlights: • Ground Source Heat Pump (GSHP) technology is suitable for both heating and cooling. • Important parameters that affect the GSHP performance has been listed. • Parameters of GSHP system has been optimized for heating and cooling mode. • Taguchi technique and utility concept are developed for GSHP optimization. - Abstract: Use of ground source energy for space heating applications through Ground Source Heat pump (GSHP) has been established as an efficient thermodynamic process. The electricity input to the GSHP can be reduced by increasing the COP of the system. However, the COP of a GSHP system will be different for heating and cooling mode operations. Hence in order to reduce the electricity input to the GSHP, an optimum value of COP has to be determined when GSHP is operated in both heating and cooling modes. In the present research, a methodology is proposed to optimize the operating parameters of a GSHP system which will operate on both heating and cooling modes. Condenser inlet temperature, condenser outlet temperature, dryness fraction at evaporator inlet and evaporator outlet temperature are considered as the influencing parameters of the heat pump. Optimization of these parameters for only heating or only cooling mode operation is achieved by employing Taguchi method for three level variations of the above parameters using an L 9 (3 4 ) orthogonal array. Higher the better concept has been used to get a higher COP. A computer program in FORTAN has been developed to carry out the computations and the results have been analyzed for the optimum conditions using Signal-to-Noise (SN) ratio and Analysis Of Variance (ANOVA) method. Based on this analysis, the maximum COP for only heating and only cooling operation are obtained as 4.25 and 3.32 respectively. By making use of the utility concept both the higher values of COP obtained for heating and cooling modes are optimized to get a single optimum COP for heating and cooling modes. A single

Transient cooling of electronics using phase change material (PCM)-based heat sinks

International Nuclear Information System (INIS)

Kandasamy, Ravi; Wang Xiangqi; Mujumdar, Arun S.

2008-01-01

Use of a phase change material (PCM)-based heat sink in transient thermal management of plastic quad flat package (QFP) electronic devices was investigated experimentally and numerically. Results show that increased power inputs enhance the melting rate as well as the thermal performance of the PCM-based heat sinks until the PCM is fully melted. A three-dimensional computational fluid dynamics model was proposed to simulate the problem and demonstrated good agreement with experimental data. Results indicate the potential for PCM-based heat sinks for use in intermittent-use devices

Adaptive distributed parameter and input estimation in linear parabolic PDEs

KAUST Repository

Mechhoud, Sarra

2016-01-01

First, new sufficient identifiability conditions of the input and the parameter simultaneous estimation are stated. Then, by means of Lyapunov-based design, an adaptive estimator is derived in the infinite-dimensional framework. It consists of a state observer and gradient-based parameter and input adaptation laws. The parameter convergence depends on the plant signal richness assumption, whereas the state convergence is established using a Lyapunov approach. The results of the paper are illustrated by simulation on tokamak plasma heat transport model using simulated data.

Free energy and heat capacity

International Nuclear Information System (INIS)

Kurata, M.; Devanathan, R.

2015-01-01

Free energy and heat capacity of actinide elements and compounds are important properties for the evaluation of the safety and reliable performance of nuclear fuel. They are essential inputs for models that describe complex phenomena that govern the behaviour of actinide compounds during nuclear fuels fabrication and irradiation. This chapter introduces various experimental methods to measure free energy and heat capacity to serve as inputs for models and to validate computer simulations. This is followed by a discussion of computer simulation of these properties, and recent simulations of thermophysical properties of nuclear fuel are briefly reviewed. (authors)

Theoretical and experimental studies on transient forced convection heat transfer of helium gas

International Nuclear Information System (INIS)

Liu, Qiusheng; Fukuda, Katsuya; Shibahara, Makoto

2008-01-01

Forced convection transient heat transfer for helium gas at various periods of exponential increase of heat input to a horizontal cylinder and a plate (ribbon) one was experimentally and theoretically studied. In the experimental studies, the authors measured heat flux, surface temperature, and transient heat transfer coefficients for forced convection flow of helium gas over a horizontal cylinder and a plate (ribbon) one under wide experimental conditions. Empirical correlations for quasi-steady-state heat transfer and transient heat transfer were obtained based on the experimental data. In the theoretical study, transient heat transfer was numerically solved based on a turbulent flow model. The values of numerical solution for surface temperature and heat flux were compared and discussed with authors' experimental data. (author)

Simulation Study of the Energy Performance of Different Space Heating Methods in Plus-energy Housing

DEFF Research Database (Denmark)

Schøtt, Jacob; Andersen, Mads E.; Kazanci, Ongun Berk

2016-01-01

Due to a shortage of energy resources, the focus on indoor environment and energy use in buildings is increasing which sets higher standards for the performance of HVAC systems in buildings. The variety of available heating systems for both residential buildings and office buildings is therefore...... cases the heat source was a natural gas fired condensing boiler, and for the floor heating cases also an air-to-water heat pump was used to compare two heat sources. The systems were also compared in terms of auxiliary energy use for pumps and fans. The results show that the investigated floor heating...... from the low temperature heating potential since an increased floor covering requires higher average water temperatures in the floor loops and decreases the COP of the heat pump. The water-based heating systems required significantly less auxiliary energy input compared to the air-based heating system...

The great 2006 heat wave over California and Nevada: Signal of an increasing trend

Science.gov (United States)

Gershunov, A.; Cayan, D.R.; Iacobellis, S.F.

2009-01-01

Most of the great California-Nevada heat waves can be classified into primarily daytime or nighttime events depending on whether atmospheric conditions are dry or humid. A rash of nighttime-accentuated events in the last decade was punctuated by an unusually intense case in July 2006, which was the largest heat wave on record (1948-2006). Generally, there is a positive trend in heat wave activity over the entire region that is expressed most strongly and clearly in nighttime rather than daytime temperature extremes. This trend in nighttime heat wave activity has intensified markedly since the 1980s and especially since 2000. The two most recent nighttime heat waves were also strongly expressed in extreme daytime temperatures. Circulations associated with great regional heat waves advect hot air into the region. This air can be dry or moist, depending on whether a moisture source is available, causing heat waves to be expressed preferentially during day or night. A remote moisture source centered within a marine region west of Baja California has been increasing in prominence because of gradual sea surface warming and a related increase in atmospheric humidity. Adding to the very strong synoptic dynamics during the 2006 heat wave were a prolonged stream of moisture from this southwestern source and, despite the heightened humidity, an environment in which afternoon convection was suppressed, keeping cloudiness low and daytime temperatures high. The relative contributions of these factors and possible relations to global warming are discussed. ?? 2009 American Meteorological Society.

On the importance of specific heats as regards efficiency increases for highly dilute IC engines

International Nuclear Information System (INIS)

Caton, Jerald A.

2014-01-01

Highlights: • Importance of specific heats towards increasing engine efficiency was quantified. • Decreases of specific heats contribute 3.5–6.3% (abs) to the efficiency. • Dilute engines benefit from decreases of specific heats due to lower temperatures. - Abstract: Engineering and scientific efforts continue with the development of advanced, IC engines using highly dilute mixtures, and relatively high compression ratios. Such engines are known to provide opportunities for low emissions as well as high efficiencies. The main features of these engines include higher compression ratios, lean operation, use of EGR, and shorter burn durations. First, this study reviews the quantitative contributions of each of these features as determined by an engine cycle simulation. Second, this study provides the quantitative contributions to the increased efficiency in terms of fundamental thermodynamic considerations. An automotive engine operated at 2000 rpm was selected for this study. For the conditions examined, the net indicated thermal efficiency increased from 37.0% (conventional engine) to 53.9% (high efficiency engine) – for an incremental increase of 16.9% (absolute). The contribution of increases of the ratio of specific heats towards the final thermal efficiency is quantified. This aspect has been well known, but has not been quantified for actual engines. For the various conditions examined, 21–35% of the total efficiency improvement was estimated to be due to the increase of the ratio of specific heats

Quantifying Energy and Mass Fluxes Controlling Godthåbsfjord Freshwater Input in a 5-km Simulation (1991–2012)

DEFF Research Database (Denmark)

Langen, P.L.; Mottram, R.H.; Christensen, J.H.

2015-01-01

Freshwater runoff to fjords with marine-terminating glaciers along the Greenland Ice Sheet margin has an impact on fjord circulation and potentially ice sheet mass balance through increasing heat transport to the glacier front. Here, the authors use the high-resolution (5.5 km) HIRHAM5 regional...... with observations (typically .0.9), there are biases that impact the results. In particular, overestimated albedo leads to underestimation of melt and runoff at low elevations. In the model simulation (1991–2012), the ice sheet experiences increasing energy input from the surface turbulent heat flux (up...... to elevations of 2000m) and shortwave radiation (at all elevations). Southerly wind anomalies and declining cloudiness due to an increase in atmospheric pressure over north Greenland contribute to increased summer melt. This results in declining surface mass balance (SMB), increasing surface runoff, and upward...

Increased Heat Transport in Ultra-hot Jupiter Atmospheres through H2 Dissociation and Recombination

Science.gov (United States)

Bell, Taylor J.; Cowan, Nicolas B.

2018-04-01

A new class of exoplanets is beginning to emerge: planets with dayside atmospheres that resemble stellar atmospheres as most of their molecular constituents dissociate. The effects of the dissociation of these species will be varied and must be carefully accounted for. Here we take the first steps toward understanding the consequences of dissociation and recombination of molecular hydrogen (H2) on atmospheric heat recirculation. Using a simple energy balance model with eastward winds, we demonstrate that H2 dissociation/recombination can significantly increase the day–night heat transport on ultra-hot Jupiters (UHJs): gas giant exoplanets where significant H2 dissociation occurs. The atomic hydrogen from the highly irradiated daysides of UHJs will transport some of the energy deposited on the dayside toward the nightside of the planet where the H atoms recombine into H2; this mechanism bears similarities to latent heat. Given a fixed wind speed, this will act to increase the heat recirculation efficiency; alternatively, a measured heat recirculation efficiency will require slower wind speeds after accounting for H2 dissociation/recombination.

effects of heat input on the chemical composition and hardness

African Journals Online (AJOL)

2012-07-02

Jul 2, 2012 ... fluencing liquid flow, heat and mass transfer, and the thermal cycle in the ... ther in understanding evaporation-limited weld pool temperatures in arc ..... This in- dicates that, the quantity of O2 is not large enough to reduce the ...

Increased power to heat ratio of small scale CHP plants using biomass fuels and natural gas

International Nuclear Information System (INIS)

Savola, Tuula; Fogelholm, Carl-Johan

2006-01-01

In this paper, we present a systematic study of process changes for increased power production in 1-20 MW e combined heat and power (CHP) plants. The changes are simulated, and their economic feasibility evaluated by using existing small scale CHP case plants. Increasing power production in decentralised CHP plants that operate according to a certain heat demand could reduce the fuel consumption and CO 2 emissions per power unit produced and improve the feasibility of CHP plant investments. The CHP plant process changes were simulated under design and off design conditions and an analysis of power and heat production, investment costs and CO 2 emissions was performed over the whole annual heat demand. The results show that using biomass fuels, there are profitable possibilities to increase the current power to heat ratios, 0.23-0.48, of the small scale CHP plants up to 0.26-0.56, depending on the size of the plant. The profitable changes were a two stage district heat exchanger and the addition of a steam reheater and a feed water preheater. If natural gas is used as an additional fuel, the power to heat ratio may be increased up to 0.35-0.65 by integrating a gas engine into the process. If the CO 2 savings from the changes are also taken into account, the economic feasibility of the changes increases. The results of this work offer useful performance simulation and investment cost knowledge for the development of more efficient and economically feasible small scale CHP processes

Turbulent heat transfer for heating of water in a short vertical tube

International Nuclear Information System (INIS)

Hata, Koichi; Noda, Nobuaki

2008-01-01

The turbulent heat transfer coefficients for the flow velocities (u=4.0 to 21 m/s), the inlet liquid temperatures (T in =296.5 to 353.4 K), the inlet pressures (P in =810 to 1014 kPa) and the increasing heat inputs (Q 0 exp(t/τ), τ=10, 20 and 33.3 s) are systematically measured by an experimental water loop. The Platinum test tubes of test tube inner diameters (d=3, 6 and 9 mm), heated lengths (L=32.7 to 100 mm), ratios of heated length to inner diameter (L/d=5.51 to 33.3) and wall thickness (δ=0.3, 0.4 and 0.5 mm) with surface roughness (Ra=0.40 to 0.78 μm) are used in this work. The turbulent heat transfer data for Platinum test tubes were compared with the values calculated by other workers' correlations for the turbulent heat transfer. The influence of Reynolds number (Re), Prandtl number (Pr), Dynamic viscosity (μ) and L/d on the turbulent heat transfer is investigated into details and, the widely and precisely predictable correlation of the turbulent heat transfer for heating of water in a short vertical tube is given based on the experimental data. The correlation can describe the turbulent heat transfer coefficients obtained in this work for the wide range of the temperature difference between heater inner surface temperature and average bulk liquid temperature (ΔT L =5 to 140 K) with d=3, 6 and 9 mm, L=32.7 to 100 mm and u=4.0 to 21 m/s within ±15%, difference. (author)

Turbulent heat transfer for heating of water in a short vertical tube

International Nuclear Information System (INIS)

Hata, Koichi; Noda, Nobuaki

2007-01-01

The turbulent heat transfer coefficients for the flow velocities (u=4.0 to 21 m/s), the inlet liquid temperatures (T in =296.5 to 353.4 K), the inlet pressures (P in =810 to 1014 kPa) and the increasing heat inputs (Q 0 exp(t/τ), τ=10, 20 and 33.3 s) are systematically measured by the experimental water loop. The Platinum test tubes of test tube inner diameters (d=3, 6 and 9 mm), heated lengths (L=32.7 to 100 mm), ratios of heated length to inner diameter (L/d=5.51 to 33.3) and wall thicknesses (δ=0.3, 0.4 and 0.5 mm) with surface roughness (Ra=0.40 to 0.78 μm) are used in this work. The turbulent heat transfer data for Platinum test tubes were compared with the values calculated by other workers' correlations for the turbulent heat transfer. The influences of Reynolds number (Re), Prandtl number (Pr), Dynamic viscosity (μ) and L/d on the turbulent heat transfer are investigated into details and, the widely and precisely predictable correlation of the turbulent heat transfer for heating of water in a short vertical tube is given based on the experimental data. The correlation can describe the turbulent heat transfer coefficients obtained in this work for wide range of the temperature difference between heater inner surface temperature and average bulk liquid temperature (ΔT L =5 to 140 K) with d=3, 6 and 9 mm, L=32.7 to 100 mm and u=4.0 to 21 m/s within ±15% difference. (author)

Sensing the Heat Stress by Mammalian Cells

Directory of Open Access Journals (Sweden)

Cates Jordan

2011-08-01

Full Text Available Abstract Background The heat-shock response network controls the adaptation and survival of the cell against environmental stress. This network is highly conserved and is connected with many other signaling pathways. A key element of the heat-shock network is the heat-shock transcription factor-1 (HSF, which is transiently activated by elevated temperatures. HSF translocates to the nucleus upon elevated temperatures, forming homotrimeric complexes. The HSF homotrimers bind to the heat shock element on the DNA and control the expression of the hsp70 gene. The Hsp70 proteins protect cells from thermal stress. Thermal stress causes the unfolding of proteins, perturbing thus the pathways under their control. By binding to these proteins, Hsp70 allows them to refold and prevents their aggregation. The modulation of the activity of the hsp70-promoter by the intensity of the input stress is thus critical for cell's survival. The promoter activity starts from a basal level and rapidly increases once the stress is applied, reaches a maximum level and attenuates slowely back to the basal level. This phenomenon is the hallmark of many experimental studies and of all computational network analysis. Results The molecular construct used as a measure of the response to thermal stress is a Hsp70-GFP fusion gene transfected in Chinese hamster ovary (CHO cells. The time profile of the GFP protein depends on the transient activity, Transient(t, of the heat shock system. The function Transient(t depends on hsp70 promoter activity, transcriptional regulation and the translation initiation effects elicited by the heat stress. The GFP time profile is recorded using flow cytometry measurements, a technique that allows a quantitative measurement of the fluorescence of a large number of cells (104. The GFP responses to one and two heat shocks were measured for 261 conditions of different temperatures and durations. We found that: (i the response of the cell to two

Input energy measurement toward warm dense matter generation using intense pulsed power generator

Science.gov (United States)

Hayashi, R.; Ito, T.; Ishitani, T.; Tamura, F.; Kudo, T.; Takakura, N.; Kashine, K.; Takahashi, K.; Sasaki, T.; Kikuchi, T.; Harada, Nob.; Jiang, W.; Tokuchi, A.

2016-05-01

In order to investigate properties of warm dense matter (WDM) in inertial confinement fusion (ICF), evaluation method for the WDM with isochoric heating on the implosion time-scale using an intense pulsed power generator ETIGO-II (∼1 TW, ∼50 ns) has been considered. In this study, the history of input energy into the sample is measured from the voltage and the current waveforms. To achieve isochoric heating, a foamed aluminum with pore sizes 600 μm and with 90% porosity was packed into a hollow glass capillary (ø 5 mm × 10 mm). The temperature of the sample is calculated from the numerical calculation using the measured input power. According to the above measurements, the input energy into a sample and the achievable temperature are estimated to be 300 J and 6000 K. It indicates that the WDM state is generated using the proposed method with ICF implosion time-scale.

Fouling resistance prediction using artificial neural network nonlinear auto-regressive with exogenous input model based on operating conditions and fluid properties correlations

Energy Technology Data Exchange (ETDEWEB)

Biyanto, Totok R. [Department of Engineering Physics, Institute Technology of Sepuluh Nopember Surabaya, Surabaya, Indonesia 60111 (Indonesia)

2016-06-03

Fouling in a heat exchanger in Crude Preheat Train (CPT) refinery is an unsolved problem that reduces the plant efficiency, increases fuel consumption and CO{sub 2} emission. The fouling resistance behavior is very complex. It is difficult to develop a model using first principle equation to predict the fouling resistance due to different operating conditions and different crude blends. In this paper, Artificial Neural Networks (ANN) MultiLayer Perceptron (MLP) with input structure using Nonlinear Auto-Regressive with eXogenous (NARX) is utilized to build the fouling resistance model in shell and tube heat exchanger (STHX). The input data of the model are flow rates and temperatures of the streams of the heat exchanger, physical properties of product and crude blend data. This model serves as a predicting tool to optimize operating conditions and preventive maintenance of STHX. The results show that the model can capture the complexity of fouling characteristics in heat exchanger due to thermodynamic conditions and variations in crude oil properties (blends). It was found that the Root Mean Square Error (RMSE) are suitable to capture the nonlinearity and complexity of the STHX fouling resistance during phases of training and validation.

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.

Analysis of hybrid electric/thermofluidic inputs for wet shape memory alloy actuators

Science.gov (United States)

Flemming, Leslie; Mascaro, Stephen

2013-01-01

A wet shape memory alloy (SMA) actuator is characterized by an SMA wire embedded within a compliant fluid-filled tube. Heating and cooling of the SMA wire produces a linear contraction and extension of the wire. Thermal energy can be transferred to and from the wire using combinations of resistive heating and free/forced convection. This paper analyzes the speed and efficiency of a simulated wet SMA actuator using a variety of control strategies involving different combinations of electrical and thermofluidic inputs. A computational fluid dynamics (CFD) model is used in conjunction with a temperature-strain model of the SMA wire to simulate the thermal response of the wire and compute strains, contraction/extension times and efficiency. The simulations produce cycle rates of up to 5 Hz for electrical heating and fluidic cooling, and up to 2 Hz for fluidic heating and cooling. The simulated results demonstrate efficiencies up to 0.5% for electric heating and up to 0.2% for fluidic heating. Using both electric and fluidic inputs concurrently improves the speed and efficiency of the actuator and allows for the actuator to remain contracted without continually delivering energy to the actuator, because of the thermal capacitance of the hot fluid. The characterized speeds and efficiencies are key requirements for implementing broader research efforts involving the intelligent control of electric and thermofluidic networks to optimize the speed and efficiency of wet actuator arrays.

Post-BEMUSE Reflood Model Input Uncertainty Methods (PREMIUM) Benchmark Phase II: Identification of Influential Parameters

International Nuclear Information System (INIS)

Kovtonyuk, A.; Petruzzi, A.; D'Auria, F.

2015-01-01

proposed in Specifications, and others used their own methodologies. This fact was a partial reason for the different ranges of input parameter variation identified by participants, in addition to differences of the physical models adopted by the different codes. Therefore, such different variation ranges of IP and, correspondingly, such different variation ranges of cladding temperature and time of re-wet, make rather difficult the task of meaningful and easy-comprehensible comparison of Phase II results. Out of a total of 72 input parameters, initially considered by all participants, only 6 were identified as influential by more than 4 participants that are: - bundle power; - wall heat transfer coefficient; - interphase friction coefficient; - interphase heat transfer coefficient; - heat transfer (enhancement) at the quench front; - droplet diameter. It should be noted that actual parameters considered in parameter 'Heat transfer (enhancement) at the quench front' are code-specific and may have different influence on calculation results. Several participants discarded some identified influential parameters (e.g., droplet diameter) due to existing relation between this kind of parameters so-called 'Input Coefficient Parameters' and more global parameters (e.g. interfacial friction coefficient and interphase heat transfer coefficient which use the droplet diameter) so-called 'Input Global Parameters'. Some participants also discarded identified influential so-called 'Input Basic Coefficients' (e.g. bundle power) since their uncertainty has not to be determined in the Phase III but will be provided by the coordinator from experimental data. The behaviour of the variation of the responses at the extremes of IP range of variation greatly depends on the type of input parameter and on the code used. Mainly, the following two different behaviours can be characterized: - For some parameters, like power, wall heat transfer and interphase

The influence of a vertical ground heat exchanger length on the electricity consumption of the heat pumps

Energy Technology Data Exchange (ETDEWEB)

Michopoulos, A.; Kyriakis, N. [Process Equipment Design Laboratory, Mechanical Engineer Department, Aristotle University of Thessaloniki (AUTh), P.O. Box 487, 541 24 Thessaloniki (Greece)

2010-07-15

The use of heat pumps combined with vertical ground heat exchangers for heating and cooling of buildings, has significantly gained popularity in recent years. The design method for these systems, as it is proposed by ASHRAE, is taking into account the maximum thermal and cooling loads of the building, the thermophysical properties of the soil at the area of installation and a minimum Coefficient of Performance (COP) of the heat pumps. This approach usually results in larger than needed length of the ground heat exchanger, thus increasing the installation cost. A new analytical simulation tool, capable to determine the required ground heat exchanger length has been developed at the Process Equipment Design Laboratory (PEDL) of the AUTh. It models the function of the system as a whole over long time periods, e.g. 20 years, using as input parameters the thermal and cooling loads of the building, the thermophysical properties of the borehole and the characteristic curves of the heat pumps. The results include the electricity consumption of the heat pumps and the heat absorbed from or rejected to the ground. The aim of this paper is to describe the developed simulation algorithm and present the results of such a simulation in a case study. It is proved that the total required length of the ground heat exchanger is less than that calculated using the common numerical method. (author)

Device and method for measuring the coefficient of performance of a heat pump

Science.gov (United States)

Brantley, V.R.; Miller, D.R.

1982-05-18

A method and instrument is provided which allows quick and accurate measurement of the coefficient of performance of an installed electrically powered heat pump including auxiliary resistane heaters. Temperature-sensitive resistors are placed in the return and supply air ducts to measure the temperature increase of the air across the refrigerant and resistive-heating elements of the system. The voltages across the resistors which are directly proportional to the respective duct tempertures are applied to the inputs of a differential amplifier so that its output voltage is proportional to the temperature difference across the unit. A voltage-to-frequency converter connected to the output of the differential amplifier converts the voltage signal to a proportional-frequency signal. A digital watt meter is used to measure the power to the unit and produces a signal having a frequency proportional to the input power. A digital logic circuit ratios the temperature difference signal and the electric power input signal in a unique manner to produce a single number which is the coefficient of performance of the unit over the test interval. The digital logic and an in-situ calibration procedure enables the instrument to make these measurements in such a way that the ratio of heat flow/power input is obtained without computations. No specialized knowledge of thermodynamics or electrons is required to operate the instrument.

Numerical analysis for the conjugate heat transfer of skin under various temperature conditions of contrast therapy

Energy Technology Data Exchange (ETDEWEB)

Park, Da Ae; Oh, Han Nah; Choi, Hyoung Gwon [Dept. of Mechanical and Automotive Engineering, Seoul National University of Science and Technology, Seoul (Korea, Republic of); Jeon, Byoung Jin; Kim, Eun Jeoung; Lee, Seung Deok [Yonsei University, Seoul (Korea, Republic of)

2015-11-15

In this paper, the contrast therapy of skin was numerically investigated by solving the conjugate heat transfer problem. A finite volume method based on the SIMPLE algorithm was adopted to solve the axisymmetric incompressible Navier-Stokes equations, coupled with an energy equation. These equations are strongly coupled with the Pennes bio-heat equation in order to consider the effect of blood perfusion rate. We investigated the thermal response of skin at some selected depths for various input temperature profiles of a stimulator for contrast therapy. From the numerical simulations, the regions with cold/hot threshold temperatures were found for five input temperature profiles. It was shown that the temperature varies mildly for different input profiles as the depth increases, owing to the Pennes effect. The input temperatures for effective hot/cold stimulation of dermis layer were found to be 47 degrees C and 7 degrees C, respectively. The present numerical results will be used for finding an optimal temperature profile of a stimulator for contrast therapy.

Wastewater as a Heat Source for Individual Residence Heating: A Techno-economic Feasibility Study in the Brussels Capital Region

Directory of Open Access Journals (Sweden)

Jan Spriet

2017-09-01

Full Text Available A large part of the thermal energy in buildings is lost through the drain and ends up as warm wastewater in the sewer system. The installation of heat exchangers in the sewer system enables a rise of the source temperature of heat pumps, increasing their coefficient of performance. To investigate the potential of such a technique in the Brussels Capital Region, a test facility named MYRTES has been installed in the sewer network, the starting point of this facility being to have one heat recovery system per residence. To estimate the heat recovery rate, potentially available in the Brussels Capital Region, the data from this test facility have been used as inputs and validation for a predictive model, considering both the heat recovery and its financial and environmental implications. Simulations show a minimum heating power of the heat pump of 6.3 kW, at a hot water temperature of 45 °C. A maximum of 35% of the buildings in the Brussels Capital Region are eligible for the use of such a system. At current tariffs, the levelized cost of energy for these systems, is lower than for traditional air heat pumps, but is higher than for gas boiler systems. The total equivalent warming impact, however, is estimated to be around 49% lower than for gas boiler systems and around 13% lower than for air heat pumps. In conclusion, heating through these types of systems is more expensive than gas boiler systems, but with increased consumption the competitiveness of these systems improves.

Comparative assessment of alternative cycles for waste heat recovery and upgrade

International Nuclear Information System (INIS)

Little, Adrienne B.; Garimella, Srinivas

2011-01-01

Thermally activated systems based on sorption cycles, as well as mechanical systems based on vapor compression/expansion are assessed in this study for waste heat recovery applications. In particular, ammonia-water sorption cycles for cooling and mechanical work recovery, a heat transformer using lithium bromide-water as the working fluid pair to yield high temperature heat, and organic Rankine cycles using refrigerant R245fa for work recovery as well as versions directly coupled to a vapor compression cycle to yield cooling are analyzed with overall heat transfer conductances for heat exchangers that use similar approach temperature differences for each cycle. Two representative cases are considered, one for smaller-scale and lower temperature applications using waste heat at 60 o C, and the other for larger-scale and higher temperature waste heat at 120 o C. Comparative assessments of these cycles on the basis of efficiencies and system footprints guide the selection of waste heat recovery and upgrade systems for different applications and waste heat availabilities. Furthermore, these considerations are used to investigate four case studies for waste heat recovery for data centers, vehicles, and process plants, illustrating the utility and limitations of such solutions. The increased implementation of such waste heat recovery systems in a variety of applications will lead to decreased primary source inputs and sustainable energy utilization. -- Highlights: → Sorption and mechanical pathways for the conversion of waste heat streams to work, cooling, and temperature boosting were investigated. → Waste heat sources including 300 W of energy at 60 o C and 1 kW of energy at 120 o C were analyzed. → Up to about seventy percent of the input waste heat can be converted to cooling. → Up to about ten percent can be converted to work. → Up to about 47 percent can be upgraded to a higher temperature.

The analysis of Alfven wave current drive and plasma heating in TCABR tokamak

International Nuclear Information System (INIS)

Ruchko, L.F.; Lerche, E.A.; Galvao, R.M.O.; Elfimov, A.G.; Nascimento, I.C.; Sa, W.P. de; Sanada, E.; Elizondo, J.I.; Ferreira, A.A.; Saettone, E.A.; Severo, J.H.F.; Bellintani, V.; Usuriaga, O.N.

2002-01-01

The results of experiments on Alfven wave current drive and plasma heating in the TCABR tokamak are analyzed with the help of a numerical code for simulation of the diffusion of the toroidal electric field. It permits to find radial distributions of plasma current density and conductivity, which match the experimentally measured total plasma current and loop voltage changes, and thus to study the performance of the RF system during Alfven wave plasma heating and current drive experiments. Regimes with efficient RF power input in TCABR have been analyzed and revealed the possibility of noninductive current generation with magnitudes up to ∼8 kA. The increase of plasma energy content due to RF power input is consistent with the diamagnetic measurements. (author)

Dynamic ignition regime of condensed system by radiate heat flux

International Nuclear Information System (INIS)

Arkhipov, V A; Zolotorev, N N; Korotkikh, A G; Kuznetsov, V T

2017-01-01

The main ignition characteristics of high-energy materials are the ignition time and critical heat flux allowing evaluation of the critical conditions for ignition, fire and explosive safety for the test solid propellants. The ignition process is typically studied in stationary conditions of heat input at constant temperature of the heating surface, environment or the radiate heat flux on the sample surface. In real conditions, ignition is usually effected at variable time-dependent values of the heat flux. In this case, the heated layer is formed on the sample surface in dynamic conditions and significantly depends on the heat flux change, i.e. increasing or decreasing falling heat flux in the reaction period of the propellant sample. This paper presents a method for measuring the ignition characteristics of a high-energy material sample in initiation of the dynamic radiant heat flux, which includes the measurement of the ignition time when exposed to a sample time varying radiant heat flux given intensity. In case of pyroxyline containing 1 wt. % of soot, it is shown that the ignition times are reduced by 20–50 % depending on the initial value of the radiant flux density in initiation by increasing or decreasing radiant heat flux compared with the stationary conditions of heat supply in the same ambient conditions. (paper)

Numerical analysis of the heat source characteristics of a two-electrode TIG arc

International Nuclear Information System (INIS)

Ogino, Y; Hirata, Y; Nomura, K

2011-01-01

Various kinds of multi-electrode welding processes are used to ensure high productivity in industrial fields such as shipbuilding, automotive manufacturing and pipe fabrication. However, it is difficult to obtain the optimum welding conditions for a specific product, because there are many operating parameters, and because welding phenomena are very complicated. In the present research, the heat source characteristics of a two-electrode TIG arc were numerically investigated using a 3D arc plasma model with a focus on the distance between the two electrodes. The arc plasma shape changed significantly, depending on the electrode spacing. The heat source characteristics, such as the heat input density and the arc pressure distribution, changed significantly when the electrode separation was varied. The maximum arc pressure of the two-electrode TIG arc was much lower than that of a single-electrode TIG. However, the total heat input of the two-electrode TIG arc was nearly constant and was independent of the electrode spacing. These heat source characteristics of the two-electrode TIG arc are useful for controlling the heat input distribution at a low arc pressure. Therefore, these results indicate the possibility of a heat source based on a two-electrode TIG arc that is capable of high heat input at low pressures.

A thermoacoustic engine capable of utilizing multi-temperature heat sources

International Nuclear Information System (INIS)

Qiu Limin; Wang Bo; Sun Daming; Liu Yu; Steiner, Ted

2009-01-01

Low-grade energy is widespread. However, it cannot be utilized with high thermal efficiency directly. Following the principle of thermal energy cascade utilization, a thermoacoustic engine (TE) with a new regenerator that can be driven by multiple heat sources at different temperature levels is proposed. Taking a regenerator that utilizes heat sources at two temperatures as an example, theoretical research has been conducted on a traveling-wave TE with the new regenerator to predict its performance. Experimental verification is also done to demonstrate the benefits of the new regenerator. Results indicate that a TE with the new regenerator utilizing additional heat at a lower temperature experiences an increase in pressure ratio, acoustic power, efficiency, and exergy efficiency with proper heat input at an appropriate temperature at the mid-heater. A regenerator that uses multi-temperature heat sources can provide a means of recovering lower grade heat.

Ion heat conduction losses in Extrap

International Nuclear Information System (INIS)

Tennfors, E.

1989-08-01

The classical ion heat conduction losses in Extrap discharges are calculated using polynomial magnetic field profiles and compared to the power input. For polynomials matched to magnetic field profiles measured in present experiments, these losses are small. By varying the coefficients of the polynomials, a region is found, where the power input can balance the classical heat conduction losses. Each set of coefficients corresponds to values of the parameters F and Θ used in RFP physics. The region determines a region in an F-Θ diagram, including the usual RFP region but extending to higher values of Θ and βΘ

Experimental investigation on an integrated thermal management system with heat pipe heat exchanger for electric vehicle

International Nuclear Information System (INIS)

Zou, Huiming; Wang, Wei; Zhang, Guiying; Qin, Fei; Tian, Changqing; Yan, Yuying

2016-01-01

Highlights: • An integrated thermal management system is proposed for electric vehicle. • The parallel branch of battery chiller can supply additional cooling capacity. • Heat pipe performance on preheating mode is better than that on cooling mode. • Heat pipe heat exchanger is a feasible choice for battery thermal management. - Abstract: An integrated thermal management system combining a heat pipe battery cooling/preheating system with the heat pump air conditioning system is presented to fulfill the comprehensive energy utilization for electric vehicles. A test bench with battery heat pipe heat exchanger and heat pump air conditioning for a regular five-chair electric car is set up to research the performance of this integrated system under different working conditions. The investigation results show that as the system is designed to meet the basic cabinet cooling demand, the additional parallel branch of battery chiller is a good way to solve the battery group cooling problem, which can supply about 20% additional cooling capacity without input power increase. Its coefficient of performance for cabinet heating is around 1.34 at −20 °C out-car temperature and 20 °C in-car temperature. The specific heat of the battery group is tested about 1.24 kJ/kg °C. There exists a necessary temperature condition for the heat pipe heat exchanger to start action. The heat pipe heat transfer performance is around 0.87 W/°C on cooling mode and 1.11 W/°C on preheating mode. The gravity role makes the heat transfer performance of the heat pipe on preheating mode better than that on cooling mode.

An optimisation framework for thermal energy storage integration in a residential heat pump heating system

International Nuclear Information System (INIS)

Renaldi, R.; Kiprakis, A.; Friedrich, D.

2017-01-01

Highlights: • An integrated framework for the optimal design of low carbon heating systems. • Development of a synthetic heat demand model with occupancy profiles. • Linear model of a heat pump with thermal energy storage heating system. • Evaluation of domestic heating system from generally available input parameters. • The lower carbon heating system can be cost competitive with conventional systems. - Abstract: Domestic heating has a large share in the UK total energy consumption and significant contribution to the greenhouse gas emissions since it is mainly fulfilled by fossil fuels. Therefore, decarbonising the heating system is essential and an option to achieve this is by heating system electrification through heat pumps (HP) installation in combination with renewable power generation. A potential increase in performance and flexibility can be achieved by pairing HP with thermal energy storage (TES), which allows the shifting of heat demand to off peak periods or periods with surplus renewable electricity. We present a design and operational optimisation model which is able to assess the performance of HP–TES relative to conventional heating systems. The optimisation is performed on a synthetic heat demand model which requires only the annual heat demand, temperature and occupancy profiles. The results show that the equipment and operational cost of a HP system without TES are significantly higher than for a conventional system. However, the integration of TES and time-of-use tariffs reduce the operational cost of the HP systems and in combination with the Renewable Heating Incentive make the HP systems cost competitive with conventional systems. The presented demand model and optimisation procedure will enable the design of low carbon district heating systems which integrate the heating system with the variable renewable electricity supply.

Heat sources for bright-rimmed molecular clouds: CO observations of NGC 7822

International Nuclear Information System (INIS)

Elmegreen, B.G.; Dickinson, D.F.; Lada, C.J.

1978-01-01

Observations of the 2.6 mm carbon monoxide line in the bright rim NGC 7822 reveal that the peak excitation and column density of the molecule lie in a ridge ahead of the ionization front. Several possibilities for the excitation of this ridge are discussed. Cosmic rays are shown to provide an excellent heat source for Bok globules, but they can account for only approx.20% of the required heating in NGC 7822. Direct shock or compressional heating of the gas could be adequate only if the pressure inside the cloud is much larger than the thermal pressure. If, in fact, this internal pressure is determined by the source of line broadening (e.g., magnetic fields or turbulence), then shock or compressional heating could be important, and pressure equilibrium may exist between the neutral cloud and the bright rim. Heating by warm grains or by the photoelectric effect is also considered, but such mechanisms are probably not important if the only source of radiation is external to the cloud. This is primarily a result of the low cloud density (approx.10 3 cm -3 ) inferred from our observations. The extent to which unknown embedded stars may provide the required gaseous heating cannot be estimated from our observations of NGC 7822.An interesting and new heat source is suggested which may have important applications to bright-rimmed clouds or to any other predominantly neutral clouds that may have undergone some recent compression. We suggest that the heat input to neutral gas due to the relaxation of internal magnetic fields will be greatly enhanced during cloud compression (with or without a shock). We show that the power input to the gas will increase more with increasing density than will the cooling rate. As a result, cloud compression can lead to an increase in the gas temperature for a period lasting several million years, which is the decay time of the compressed field. The observed ridge in NGC 7822 may be due to stimulated release of internal magnetic energy

SIRTF thermal design modifications to increase lifetime

Science.gov (United States)

Petrick, S. W.

1993-01-01

An effort was made to increase the predicted lifetime of the SIRTF dewar by lowering the exterior shell temperature, increasing the radiated energy from the vapor cooled shields and reconfiguring the vapor cooled shields. The lifetime increases can be used to increase the scientific return from the mission and as a trade-off against mass and cost. This paper describes the configurations studied, the steady state thermal model used, the analytical methods and the results of the analysis. Much of the heat input to the outside dewar shell is radiative heat transfer from the solar panel. To lower the shell temperature, radiative cooled shields were placed between the solar panel and the dewar shell and between the bus and the dewar shell. Analysis showed that placing a radiator on the outer vapor cooled shield had a significant effect on lifetime. Lengthening the distance between the outer shell and the point where the vapor cooled shields are attached to the support straps also improved lifetime.

The rubber hand illusion increases heat pain threshold.

Science.gov (United States)

Hegedüs, G; Darnai, G; Szolcsányi, T; Feldmann, Á; Janszky, J; Kállai, J

2014-09-01

Accumulating evidence shows that manipulations of cortical body representation, for example, by simply viewing one's own body, can relieve pain in healthy subjects. Despite the widespread use of the rubber hand illusion (RHI) as an effective experimental tool for the manipulation of bodily awareness, previous studies examining the analgesic effect of the RHI have produced conflicting results. We used noxious heat stimuli to induce finger pain in 29 healthy subjects, and we recorded the participants' pain thresholds and subjective pain ratings during the RHI and during the control conditions. Two control conditions were included in our experiment - a standard one with reduced illusion strength (asynchronous stroking control) and an additional one in which the participants viewed their own hand. Raw data showed that both the RHI and the vision of the own hand resulted in slightly higher pain thresholds than the asynchronous stroking control (illusion: 47.79 °C; own-hand: 47.99 °C; asynchronous: 47.52 °C). After logarithmic transformation to achieve normality, paired t-tests revealed that both increases in pain threshold were significant (illusion/asynchronous: p = 0.036; own-hand/asynchronous: p = 0.007). In contrast, there was no significant difference in pain threshold between the illusion and the own-hand conditions (p = 0.656). Pain rating scores were not log-normal, and Wilcoxon singed-rank tests found no significant differences in pain ratings between the study conditions. The RHI increases heat pain threshold and the analgesic effect of the RHI is comparable with that of seeing one's own hand. The latter finding may have clinical implications. © 2014 European Pain Federation - EFIC®

Quasi-adaptive fuzzy heating control of solar buildings

Energy Technology Data Exchange (ETDEWEB)

Gouda, M.M. [Faculty of Industrial Education, Cairo (Egypt); Danaher, S. [University of Northumbria, Newcastle upon Tyne, (United Kingdom). School of Engineering; Underwood, C.P. [University of Northumbria, Newcastle upon Tyne (United Kingdom). School of Built Environment and Sustainable Cities Research Institute

2006-12-15

Significant progress has been made on maximising passive solar heat gains to building spaces in winter. Control of the space heating in these applications is complicated due to the lagging influence of the useful solar heat gain coupled with the wide range of construction materials and heating system choices. Additionally, and in common with most building control applications, there is a need to develop control solutions that permit simple and transparent set-up and commissioning procedures. This paper addresses the development and testing of a quasi-adaptive fuzzy logic control method that addresses these issues. The controller is developed in two steps. A feed-forward neural network is used to predict the internal air temperature, in which a singular value decomposition (SVD) algorithm is used to remove the highly correlated data from the inputs of the neural network to reduce the network structure. The fuzzy controller is then designed to have two inputs: the first input being the error between the set-point temperature and the internal air temperature and the second the predicted future internal air temperature. The controller was implemented in real-time using a test cell with controlled ventilation and a modulating electric heating system. Results, compared with validated simulations of conventionally controlled heating, confirm that the proposed controller achieves superior tracking and reduced overheating when compared with the conventional method of control. (author)

On post-weld heat treatment cracking in tig welded superalloy ATI 718Plus

Science.gov (United States)

Asala, G.; Ojo, O. A.

The susceptibility of heat affected zone (HAZ) to cracking in Tungsten Inert Gas (TIG) welded Allvac 718Plus superalloy during post-weld heat treatment (PWHT) was studied. Contrary to the previously reported case of low heat input electron beam welded Allvac 718Plus, where HAZ cracking occurred during PWHT, the TIG welded alloy is crack-free after PWHT, notwithstanding the presence of similar micro-constituents that caused cracking in the low input weld. Accordingly, the formation of brittle HAZ intergranular micro-constituents may not be a sufficient factor to determine cracking propensity, the extent of heat input during welding may be another major factor that influences HAZ cracking during PWHT of the aerospace superalloy Allvac 718Plus.

Workplace heat stress, health and productivity ? an increasing challenge for low and middle-income countries during climate change

OpenAIRE

Kjellstrom, Tord; Holmer, Ingvar; Lemke, Bruno

2009-01-01

Background: Global climate change is already increasing the average temperature and direct heat exposure in many places around the world. Objectives: To assess the potential impact on occupational health and work capacity for people exposed at work to increasing heat due to climate change. Design: A brief review of basic thermal physiology mechanisms, occupational heat exposure guidelines and heat exposure changes in selected cities. Results: In countries with very hot seasons, workers are al...

Inverse Estimation of Heat Flux and Temperature Distribution in 3D Finite Domain

International Nuclear Information System (INIS)

Muhammad, Nauman Malik

2009-02-01

Inverse heat conduction problems occur in many theoretical and practical applications where it is difficult or practically impossible to measure the input heat flux and the temperature of the layer conducting the heat flux to the body. Thus it becomes imperative to devise some means to cater for such a problem and estimate the heat flux inversely. Adaptive State Estimator is one such technique which works by incorporating the semi-Markovian concept into a Bayesian estimation technique thereby developing an inverse input and state estimator consisting of a bank of parallel adaptively weighted Kalman filters. The problem presented in this study deals with a three dimensional system of a cube with one end conducting heat flux and all the other sides are insulated while the temperatures are measured on the accessible faces of the cube. The measurements taken on these accessible faces are fed into the estimation algorithm and the input heat flux and the temperature distribution at each point in the system is calculated. A variety of input heat flux scenarios have been examined to underwrite the robustness of the estimation algorithm and hence insure its usability in practical applications. These include sinusoidal input flux, a combination of rectangular, linearly changing and sinusoidal input flux and finally a step changing input flux. The estimator's performance limitations have been examined in these input set-ups and error associated with each set-up is compared to conclude the realistic application of the estimation algorithm in such scenarios. Different sensor arrangements, that is different sensor numbers and their locations are also examined to impress upon the importance of number of measurements and their location i.e. close or farther from the input area. Since practically it is both economically and physically tedious to install more number of measurement sensors, hence optimized number and location is very important to determine for making the study more

Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC

Science.gov (United States)

Mikielewicz, Dariusz; Mikielewicz, Jarosław

2011-12-01

In the paper presented is a novel concept to utilize the heat from the turbine bleed to improve the quality of working fluid vapour in the bottoming organic Rankine cycle (ORC). That is a completely novel solution in the literature, which contributes to the increase of ORC efficiency and the overall efficiency of the combined system of the power plant and ORC plant. Calculations have been accomplished for the case when available is a flow rate of low enthalpy hot water at a temperature of 90 °C, which is used for preliminary heating of the working fluid. That hot water is obtained as a result of conversion of exhaust gases in the power plant to the energy of hot water. Then the working fluid is further heated by the bleed steam to reach 120 °C. Such vapour is subsequently directed to the turbine. In the paper 5 possible working fluids were examined, namely R134a, MM, MDM, toluene and ethanol. Only under conditions of 120 °C/40 °C the silicone oil MM showed the best performance, in all other cases the ethanol proved to be best performing fluid of all. Results are compared with the "stand alone" ORC module showing its superiority.

Heat transfer mechanisms in poplar wood undergoing torrefaction

Science.gov (United States)

Sule, Idris O.; Mahmud, Shohel; Dutta, Animesh; Tasnim, Syeda Humaira

2016-03-01

Torrefaction, a thermal treatment process of biomass, has been proved to improve biomass combustible properties. Torrefaction is defined as a thermochemical process in reduced oxygen condition and at temperature range from 200 to 300 °C for shorter residence time whereby energy yield is maximized, can be a bridging technology that can lead the conventional system (e.g. coal-fired plants) towards a sustainable energy system. In efforts to develop a commercial operable torrefaction reactor, the present study examines the minimum input condition at which biomass is torrefied and explores the heat transfer mechanisms during torrefaction in poplar wood samples. The heat transfer through the wood sample is numerically modeled and analyzed. Each poplar wood is torrefied at temperature of 250, 270, and 300 °C. The experimental study shows that the 270 °C-treatment can be deduced as the optimal input condition for torrefaction of poplar wood. A good understanding of heat transfer mechanisms can facilitate the upscaling and downscaling of torrefaction process equipment to fit the feedstock input criteria and can help to develop treatment input specifications that can maximize process efficiency.

A three-dimensional thermal-fluid analysis of flat heat pipes

Energy Technology Data Exchange (ETDEWEB)

Xiao, Bin; Faghri, Amir [Department of Mechanical Engineering, University of Connecticut, 261 Glenbrook Road, Unit 2337, Storrs, CT 06269 (United States)

2008-06-15

A detailed, three-dimensional model has been developed to analyze the thermal hydrodynamic behaviors of flat heat pipes without empirical correlations. The model accounts for the heat conduction in the wall, fluid flow in the vapor chambers and porous wicks, and the coupled heat and mass transfer at the liquid/vapor interface. The flat pipes with and without vertical wick columns in the vapor channel are intensively investigated in the model. Parametric effects, including evaporative heat input and size on the thermal and hydrodynamic behavior in the heat pipes, are investigated. The results show that, the vertical wick columns in the vapor core can improve the thermal and hydrodynamic performance of the heat pipes, including thermal resistance, capillary limit, wall temperature, pressure drop, and fluid velocities due to the enhancement of the fluid/heat mechanism form the bottom condenser to the top evaporator. The results predict that higher evaporative heat input improves the thermal and hydrodynamic performance of the heat pipe, and shortening the size of heat pipe degrades the thermal performance of the heat pipe. (author)

Heat loss and fluid leakage tests of the ROSA-III facility

International Nuclear Information System (INIS)

Suzuki, Mitsuhiro; Tasaka, Kanji; Shiba, Masayoshi

1981-12-01

The report presents characteristic test results about the steady state heat loss, one of the inherent characteristics of the ROSA-III test facility. The steady state heat loss tests were conducted at five different temperature conditions between 111 0 C and 290 0 C . Net heat loss rates were obtained by estimating the electric power supplied to the core, heat input from the recirculation pumps and steam leakage rate. The heat loss characteristics have important contribution to analyses of the ROSA-III small break tests. A following simple relation was obtained between the net heat loss rate Q*sub(HL) (kJ/s) (*: radical) of the ROSA-III facility and the temperature difference ΔT ( 0 C) between the fluid temperature of the system and the room temperature, Q*sub(HL) = 0.56 x ΔT. (*: radical) And the steam leak flow at normal operating condition of the ROSA-III test, (P = 7.2 MPa) was obtained as 8.9 x 10 -3 kg/s and corresponding steam leakage energy as 10.5 kJ/s. The heat input from the recirculation pumps was indirectly estimated under a constant speed by assuming the heat input was equal to the brake horce power of the pumps. (author)

Heat pipe heat exchanger for heat recovery in air conditioning

Energy Technology Data Exchange (ETDEWEB)

Abd El-Baky, Mostafa A.; Mohamed, Mousa M. [Mechanical Power Engineering Department, Faculty of Engineering, Minufiya University, Shebin El-Kom (Egypt)

2007-03-15

The heat pipe heat exchangers are used in heat recovery applications to cool the incoming fresh air in air conditioning applications. Two streams of fresh and return air have been connected with heat pipe heat exchanger to investigate the thermal performance and effectiveness of heat recovery system. Ratios of mass flow rate between return and fresh air of 1, 1.5 and 2.3 have been adapted to validate the heat transfer and the temperature change of fresh air. Fresh air inlet temperature of 32-40{sup o}C has been controlled, while the inlet return air temperature is kept constant at about 26{sup o}C. The results showed that the temperature changes of fresh and return air are increased with the increase of inlet temperature of fresh air. The effectiveness and heat transfer for both evaporator and condenser sections are also increased to about 48%, when the inlet fresh air temperature is increased to 40{sup o}C. The effect of mass flow rate ratio on effectiveness is positive for evaporator side and negative for condenser side. The enthalpy ratio between the heat recovery and conventional air mixing is increased to about 85% with increasing fresh air inlet temperature. The optimum effectiveness of heat pipe heat exchanger is estimated and compared with the present experimental data. The results showed that the effectiveness is close to the optimum effectiveness at fresh air inlet temperature near the fluid operating temperature of heat pipes. (author)

Experimental investigation on the feasibility of heat pipe cooling for HEV/EV lithium-ion battery

International Nuclear Information System (INIS)

Tran, Thanh-Ha; Harmand, Souad; Desmet, Bernard; Filangi, Sebastien

2014-01-01

In this paper, the use of flat heat pipe as an effective and low-energy device to mitigate the temperature of a battery module designed for a HEV application was investigated. For this purpose, nominal heat flux generated by a battery module was reproduced and applied to a flat heat pipe cooling system. The thermal performance of the flat heat pipe cooling system was compared with that of a conventional heat sink under various cooling conditions and under several inclined positions. The results show that adding heat pipe reduced the thermal resistance of a common heat sink of 30% under natural convection and 20% under low air velocity cooling. Consequently, the cell temperature was kept below 50 °C, which cannot be achieved using heat sink. According to the space allocated for the battery pack in the vehicle, flat heat pipe can be used in vertical or horizontal position. Furthermore, flat heat pipe works efficiently under different grade road conditions. The transient behaviour of the flat heat pipe was also studied under high frequency and large amplitude variable input power. The flat heat pipe was found to handle more efficiently instant increases of the heat flux than the conventional heat sink. -- Highlights: • Constant heat flux was applied to a flat heat pipe cooling system. • Its thermal performance was compared with that of a heat sink under several cooling conditions. • The influence of the inclination was evaluated. • The heat pipe transient behaviour was also studied under variable input power. • Heat pipe was found to be an effective and low-energy solution for HEV/EV battery cooling

Spiral multiple-effect diffusion solar still coupled with vacuum-tube collector and heat pipe

KAUST Repository

Huang, Bin-Juine

2015-04-01

© 2015 Elsevier B.V. A novel solar still with spiral-shape multiple-effect diffusion unit is developed in the present study. The test results of a 14-effect unit coupled with vacuum-tube solar collector (absorber area 1.08m2) show that the highest daily pure water production is 40.6kgd-1. The measured highest productivity based on the area of glass cover, solar absorber, and evaporating surface is 34.7, 40.6, and 7.96kgm-2d-1, respectively, which are much higher than the published results. The measured solar distillation efficiency is 2.0-3.5. The performance enhancement results mainly from the lateral diffusion process in the spiraled still cell. The vapor flow generated by heat input can flow freely and laterally through the spiral channel down to the end when solar heat input is high. Besides, the larger evaporating and condensing area at the outer cell may increase heat and mass transfer at the outer cell.

Analysis of vehicle exhaust waste heat recovery potential using a Rankine cycle

International Nuclear Information System (INIS)

Domingues, António; Santos, Helder; Costa, Mário

2013-01-01

This study evaluates the vehicle exhaust WHR (waste heat recovery) potential using a RC (Rankine cycle ). To this end, both a RC thermodynamic model and a heat exchanger model have been developed. Both models use as input, experimental data obtained from a vehicle tested on a chassis dynamometer. The thermodynamic analysis was performed for water, R123 and R245fa and revealed the advantage of using water as the working fluid in applications of thermal recovery from exhaust gases of vehicles equipped with a spark-ignition engine. Moreover, the heat exchanger effectiveness for the organic working fluids R123 and R245fa is higher than that for the water and, consequently, they can also be considered appropriate for use in vehicle WHR applications through RCs when the exhaust gas temperatures are relatively low. For an ideal heat exchanger, the simulations revealed increases in the internal combustion engine thermal and vehicle mechanical efficiencies of 1.4%–3.52% and 10.16%–15.95%, respectively, while for a shell and tube heat exchanger, the simulations showed an increase of 0.85%–1.2% in the thermal efficiency and an increase of 2.64%–6.96% in the mechanical efficiency for an evaporating pressure of 2 MPa. The results confirm the advantages of using the thermal energy contained in the vehicle exhaust gases through RCs. Furthermore, the present analysis demonstrates that improved evaporator designs and appropriate expander devices allowing for higher evaporating pressures are required to obtain the maximum WHR potential from vehicle RC systems. -- Highlights: ► This study evaluates the vehicle exhaust waste heat recovery potential using Rankine cycle systems. ► A thermodynamic model and a heat exchanger model were developed. ► Experimental data obtained in a vehicle tested on a chassis dynamometer was used as models input. ► Thermodynamic analysis was performed for water, R123 and R245fa. ► Results confirm advantages of using the thermal energy

Feedforward temperature control using a heat flux microsensor

OpenAIRE

Lartz, Douglas John

1993-01-01

The concept of using heat flux measurements to provide the input for a feedforward temperature control loop is investigated. The feedforward loop is added to proportional and integral feedback control to increase the speed of the response to a disturbance. Comparison is made between the feedback and the feedback plus feedforward control laws. The control law with the feedforward control loop is also compared to the conventional approach of adding derivative control to speed up ...

New waste heat district heating system with combined heat and power based on absorption heat exchange cycle in China

International Nuclear Information System (INIS)

Sun Fangtian; Fu Lin; Zhang Shigang; Sun Jian

2012-01-01

A new waste heat district heating system with combined heat and power based on absorption heat exchange cycle (DHAC) was developed to increase the heating capacity of combined heat and power (CHP) through waste heat recovery, and enhance heat transmission capacity of the existing primary side district heating network through decreasing return water temperature by new type absorption heat exchanger (AHE). The DHAC system and a conventional district heating system based on CHP (CDH) were analyzed in terms of both thermodynamics and economics. Compared to CDH, the DHAC increased heating capacity by 31% and increased heat transmission capacity of the existing primary side district heating network by 75%. The results showed that the exergetic efficiency of DHAC was 10.41% higher and the product exergy monetary cost was 36.6¥/GJ less than a CHD. DHAC is an effective way to increase thermal utilization factor of CHP, and to reduce district heating cost. - Highlights: ► Absorption heat pumps are used to recover waste heat in CHP. ► Absorption heat exchanger can reduce exergy loss in the heat transfer process. ► New waste heat heating system (DHAC) can increase heating capacity of CHP by 31%. ► DHAC can enhance heat transmission capacity of the primary pipe network by 75%. ► DHAC system has the higher exergetic efficiency and the better economic benefit.

Investigation of pellet acceleration by an arc heated gas gun

International Nuclear Information System (INIS)

Andersen, P.; Andersen, S.A.; Bundgaard, J.; Baekmark, L.; Hansen, B.H.; Jensen, V.O.; Kossek, H.; Michelsen, P.K.; Nordskov, A.; Sass, B.; Soerensen, H.; Weisberg, K.V.

1987-06-01

This report describes work on pellet acceleration by means of an arc heated gas gun. The work is a continuation of the work described in RISO-M-2536. The aim of the work is to obtain velocities well above 2 km/s for 3.2 mm diameter deuterium pellets. By means of a cryogenic arc chamber in which the hydrogen propellant is pre-condensed, extruded deutetrium pellets are accelerated up to a maximum velocity of 1.93 km/s. When increasing the energy input to the arc in order to increase the pellet velocity further the heat input to the extrusion/punching pellet loading mechanism was found to be critical: preparation of pellets became difficult and cooling times between shots became inconveniently long. In order to circumvent this problems the concept of a room temperature hydrogen propellant pellet fed arc chamber was proposed. Preliminary results from acceleration of polyurethane pellets with this arc chamber are described as well as the work of developing of feed pellet guns for this chamber. Finally the report describes design consideration for a high pressure propellant pellet fed arc chamber together with preliminary results obtained with a proto-type arc chamber. (author)

MODELING OF THE HEAT PUMP STATION CONTROLABLE LOOP OF AN INTERMEDIATE HEAT-TRANSFER AGENT (Part II

Directory of Open Access Journals (Sweden)

Sit M.L.

2011-08-01

Full Text Available It is studied the model of the heat pump station controllable loop of an intermediate heat-transfer agent for the use in wineries. There are demonstrated transients after the disturbing action of the temperature on the input of cooling jacket of the fermentation stirred tank. There are compared different control laws of the object.

Transient thermal performance analysis of micro heat pipes

International Nuclear Information System (INIS)

Liu, Xiangdong; Chen, Yongping

2013-01-01

A theoretical analysis of transient fluid flow and heat transfer in a triangular micro heat pipes (MHP) has been conducted to study the thermal response characteristics. By introducing the system identification theory, the quantitative evaluation of the MHP's transient thermal performance is realized. The results indicate that the evaporation and condensation processes are both extended into the adiabatic section. During the start-up process, the capillary radius along axial direction of MHP decreases drastically while the liquid velocity increases quickly at the early transient stage and an approximately linear decrease in wall temperature arises along the axial direction. The MHP behaves as a first-order LTI control system with the constant input power as the 'step input' and the evaporator wall temperature as the 'output'. Two corresponding evaluation criteria derived from the control theory, time constant and temperature constant, are able to quantitatively evaluate the thermal response speed and temperature level of MHP under start-up, which show that a larger triangular groove's hydraulic diameter within 0.18–0.42 mm is able to accelerate the start-up and decrease the start-up temperature level of MHP. Additionally, the MHP starts up fastest using the fluid of ethanol and most slowly using the working fluid of methanol, and the start-up temperature reaches maximum level for acetone and minimum level for the methanol. -- Highlights: • Transient thermal response of micro heat pipe is simulated by an improved model. • Control theory is introduced to quantify the thermal response of micro heat pipe. • Evaluation criteria are proposed to represent thermal response of micro heat pipe. • Effects of groove dimensions and working fluids on start-up of micro heat pipe are evaluated

Increasing RES Penetration and Security of Energy Supply by Use of Energy Storages and Heat Pumps in Croatian Energy System

DEFF Research Database (Denmark)

Krajačić, Goran; Mathiesen, Brian Vad; Duić, Neven

2010-01-01

electricity, heat and transport demands, and including renewable energy, power plants, and combined heat and power production (CHP) for district heating. Using the 2007 energy system the wind power share is increased by two energy storage options: Pumped hydro and heat pumps in combination with heat storages....... The results show that such options can enable an increased penetration of wind power. Using pumped hydro storage (PHS) may increase wind power penetration from 0.5 TWh, for existing PHS installations and up to 6 TWh for very large installations. Using large heat pumps and heat storages in combination...... with specific regulation of power system could additionally increase wind penetration for 0.37 TWh. Hence, with the current technologies installed in the Croatian energy system the installed pumped hydro-plant may facilitate more than 10% wind power in the electricity system. Large-scale integration of wind...

Increasing the efficiency of heating systems by reducing the flue gas temperature below the dew point

Energy Technology Data Exchange (ETDEWEB)

Kremer, H.

1981-06-01

This paper deals with the fundamentals and technical possibilities of increasing the combustion efficiency of gas-fired heating units for domestic heating by cooling the flue gases below their water vapor saturation temperature. The improvement of the efficiency can be more than 15% in comparison even to modern warm water heating boilers. Important however is the availability of cooling fluids of sufficiently low temperatures which could be recirculated heating water, freshwater and air. Different possible applications of this method are discussed in detail.

Heat Control via Torque Control in Friction Stir Welding

Science.gov (United States)

Venable, Richard; Colligan, Kevin; Knapp, Alan

2004-01-01

In a proposed advance in friction stir welding, the torque exerted on the workpiece by the friction stir pin would be measured and controlled in an effort to measure and control the total heat input to the workpiece. The total heat input to the workpiece is an important parameter of any welding process (fusion or friction stir welding). In fusion welding, measurement and control of heat input is a difficult problem. However, in friction stir welding, the basic principle of operation affords the potential of a straightforward solution: Neglecting thermal losses through the pin and the spindle that supports it, the rate of heat input to the workpiece is the product of the torque and the speed of rotation of the friction stir weld pin and, hence, of the spindle. Therefore, if one acquires and suitably processes data on torque and rotation and controls the torque, the rotation, or both, one should be able to control the heat input into the workpiece. In conventional practice in friction stir welding, one uses feedback control of the spindle motor to maintain a constant speed of rotation. According to the proposal, one would not maintain a constant speed of rotation: Instead, one would use feedback control to maintain a constant torque and would measure the speed of rotation while allowing it to vary. The torque exerted on the workpiece would be estimated as the product of (1) the torque-multiplication ratio of the spindle belt and/or gear drive, (2) the force measured by a load cell mechanically coupled to the spindle motor, and (3) the moment arm of the load cell. Hence, the output of the load cell would be used as a feedback signal for controlling the torque (see figure).

Impact of high-latitude energy input on the mid- and low-latitude ionosphere and thermosphere

Science.gov (United States)

Lu, G.; Sheng, C.

2017-12-01

High-latitude energy input has a profound impact on the ionosphere and thermosphere especially during geomagnetic storms. Intense auroral particle precipitation ionizes neutral gases and modifies ionospheric conductivity; collisions between neutrals and fast-moving ions accelerate the neutral winds and produce Joule frictional heating; and the excess Joule and particle heating causes atmospheric upwelling and changes neutral composition due to the rising of the heavier, molecular-rich air. In addition, impulsive Joule heating launches large-scale gravity waves that propagate equatorward toward middle and low latitudes and even into the opposite hemisphere, altering the mean global circulation of the thermosphere. Furthermore, high-latitude electric field can also directly penetrate to lower latitudes under rapidly changing external conditions, causing prompt ionospheric variations in the mid- and low-latitude regions. To study the effects of high-latitude energy input, we apply the different convection and auroral precipitation patterns based on both empirical models and the AMIE outputs. We investigate how the mid- and low-latitude regions respond to the different specifications of high-latitude energy input. The main purpose of the study is to delineate the various dynamical, electrodynamical, and chemical processes and to determine their relative importance in the resulting ionospheric and thermospheric properties at mid and low latitudes.

Influence of iron powder addition onto heat inputs, at stainless steels welds; Influencia da adicao do po de ferro no insumo de calor e na ZAC, em soldas de aco ARBL

Energy Technology Data Exchange (ETDEWEB)

Gomes, Samuel I.N.; Spinelli, Dirceu [Sao Paulo Univ., Sao Carlos, SP (Brazil). Escola de Engenharia; Magalhaes B Goncalves, Gilberto de; Souza, Paulo C.R.D. de

1992-12-31

In this work, welding with or without iron powder addition in stainless steels were produced. The welds obtained in only one pass with three different angles of grooves and several welding condition. The results showed that the heat input changes with and without iron powder addition that were found out by the cooling rates changes in weld pool. (author). 10 refs., 4 figs., 4 tabs.

The effect of gas tungsten arc welding and pulsed-gas tungsten arc welding processes’ parameters on the heat affected zone-softening behavior of strain-hardened Al–6.7Mg alloy

International Nuclear Information System (INIS)

Hadadzadeh, Amir; Ghaznavi, Majid Mahmoudi; Kokabi, Amir Hossein

2014-01-01

Highlights: • The strain-hardened Al–6.7Mg alloy was welded using GTAW and PGTAW processes. • The HAZ softening behavior of the welding joint was characterized. • Employing pulsed current in GTAW process eliminated the HAZ softening. • Duration ratio did not affect the weld strength while the frequency influenced it. - Abstract: The heat affected zone (HAZ) softening behavior of strain-hardened Al–6.7Mg alloy welded by gas tungsten arc welding (GTAW) process was investigated. Increasing the heat input during welding led to formation of a wider HAZ. Moreover, the size of the precipitates was increased at higher heat inputs. Consequently, by increasing the heat input, lower strength was obtained for the welding joints. At the second stage of the study, pulsed-GTAW (PGTAW) process was employed to improve the strength of the joints. It was observed that the overall strength of the welding joints was improved and the fracture during tensile test was moved from the HAZ to the fusion zone. Moreover, the effect of duration ratio and pulse frequency was studied. For the current study, the duration ratio did not have a significant effect on the strength and microstructure of the weld, but increasing the frequency led to higher strength of the weld and finer microstructure

Students’ Perceived Heat-Health Symptoms Increased with Warmer Classroom Temperatures

Directory of Open Access Journals (Sweden)

Shalin Bidassey-Manilal

2016-06-01

Full Text Available Temperatures in Africa are expected to increase by the end of the century. Heat-related health impacts and perceived health symptoms are potentially a problem, especially in public schools with limited resources. Students (n = 252 aged ~14–18 years from eight high schools completed an hourly heat-health symptom log over 5 days. Data loggers measured indoor classroom temperatures. A high proportion of students felt tired (97.2%, had low concentration (96.8% and felt sleepy (94.1% during at least one hour on any day. There were statistically significant correlations, when controlling for school cluster effect and time of day, between indoor temperatures ≥32 °C and students who felt tired and found it hard to breathe. Consistently higher indoor classroom temperatures were observed in classrooms constructed of prefabricated asbestos sheeting with corrugated iron roof and converted shipping container compared to brick classrooms. Longitudinal studies in multiple seasons and different classroom building types are needed.

Studies on the characteristics of the separated heat pipe system with non-condensible gas for the use of the passive decay heat removal in reactor systems

International Nuclear Information System (INIS)

Hayashi, Takao; Ishi, Takayuki; Hayakawa, Hitoshi; Ohashi, Kazutaka

1997-01-01

Experiments on the separated heat pipe system of variable conductance type, which enclose non-condensible gas, have been carried out with intention of applying such system to passive decay heat removal of the modular reactors such as HTR plant. Basic experiments have been carried out on the experimental apparatus consisting of evaporator, vapor transfer tube, condenser tube and return tube which returns the condensed liquid back to the evaporator. Water and methanol were examined as the working fluids and nitrogen gas was enclosed as the non-condensible gas. The behaviors of the system were examined for the parametric changes of the heat input under the various pressures of nitrogen gas initially enclosed, including the case without enclosing N 2 gas for the comparison. The results of the experiments shows very clear features of self control characteristics. The self control mechanism was made clear, that is, in such system in which the condensing area in the condenser expands automatically in accordance with the increase of the heat input to keep the system temperature nearly constant. The working temperature of the system are clearly dependent on the pressure of the non-condensable gas initially enclosed, with higher system working temperature with higher initial gas pressure enclosed. The analyses were done on water and methanol as the working fluids, which show very good agreement with the experimental results. A lot of attractive applications are expected including the self switching feature with minimum heat loss during normal operation with maintaining the sufficient heat removal at accidents. (author)

Potential impact on the global atmospheric N2O budget of the increased nitrogen input required to meet future global food demands

NARCIS (Netherlands)

Mosier, A.; Kroeze, C.

2000-01-01

In most soils, biogenic formation of N2O is enhanced by an increase in available mineral N through increased nitrification and denitrification. N-fertilization, therefore, directly results in additional N2O formation. In addition, these inputs may lead to indirect formation of N2O after N leaching

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

Investigation of heat transfer and fluid flow in activating TIG welding by numerical modeling

International Nuclear Information System (INIS)

Wang, Xinxin; Huang, Jiankang; Huang, Yong; Fan, Ding; Guo, Yanning

2017-01-01

Highlights: • The heat input to the anode and subsequent thermal efficiency is almost equal for TIG and A-TIG welding. • Dominant effect heat convection and reversion of molten metal flow in weld pool causes significant increase in weld penetration. - Abstract: Heat transfer and fluid flow of arc plasma and weld pool in tungsten inert gas (TIG) welding and activated flux tungsten inert gas (A-TIG) welding of SUS 304 stainless steel are investigated comparatively though a 3D unified model. The model differs from the previous ones in that it considers the arc length more realistic for welding production. Tungsten electrode, anode (work piece) and arc plasma are all included. The effects of buoyance, plasma drag force, Lorentz force and Marangoni force on the weld pool flow are taken into account. By solving the conservation equations of mass, momentum, energy as well as Maxwell equations, the distributions of temperature and velocity of arc plasma and weld pool are obtained for TIG and A-TIG welding. The heat flux, current density and shear stress at the weld pool are presented. Dimensionless numbers are employed to compare the relative importance of the driven forces and that of convection and conduction in heat transfer of the weld pool. It is demonstrated that there is no significant difference in the heat flux at the weld pool, and total heat input to the anode and thermal efficiency is almost equal for TIG and A-TIG welding. The current density and the heat flux at the weld pool are more concentrated in more realistic welding condition. As a result, both of the temperature of the weld pool for TIG welding and A-TIG welding increases, while the latter is more significant. Marangoni force ranges from zero to 100 Pa and dominant the weld pool flow. Compared with the conventional TIG welding, the reversion of the Marangoni force results in inward flow and thus causes inward heat convection in weld pool of A-TIG welding. Heat convection was the main mechanism of

Local heat transfer measurement and thermo-fluid characterization of a pulsating heat pipe

International Nuclear Information System (INIS)

Mameli, Mauro; Marengo, Marco; Khandekar, Sameer

2014-01-01

A compact Closed Loop Pulsating Heat Pipe (CLPHP), filled with ethanol (65% v/v), made of four transparent glass tubes forming the adiabatic section and connected with copper U-turns in the evaporator and condenser sections respectively, is designed in order to perform comprehensive thermal-hydraulic performance investigation. Local heat transfer coefficient is estimated by measurement of tube wall and internal fluid temperatures in the evaporator section. Simultaneously, fluid pressure oscillations are recorded together with the corresponding flow patterns. The thermal performances are measured for different heat input levels and global orientation of the device with respect to gravity. One exploratory test is also done with azeotropic mixture of ethanol and water. Results show that a stable device operation is achieved (i.e. evaporator wall temperatures can reach a pseudo-steady-state) only when a circulating flow mode is established superimposed on local pulsating flow. The heat transfer performance strongly depends on the heat input level and the inclination angle, which, in turn, also affect the ensuing flow pattern. The spectral analysis of the pressure signal reveals that even during the stable performance regimes, characteristic fluid oscillation frequencies are not uniquely recognizable. Equivalent thermal conductivities of the order of 10-15 times that of pure copper are achieved. Due to small number of turns horizontal mode operation is not feasible. Preliminary results indicate that filling azeotropic mixture of ethanol and water as working fluid does not alter the thermal performance as compared to pure ethanol case. (authors)

Urban heat islands in the subsurface of German cities

Science.gov (United States)

Menberg, K.; Blum, P.; Zhu, K.; Bayer, P.

2012-04-01

In the subsurface of many cities there are widespread and persistent thermal anomalies (subsurface urban heat islands) that result in a warming of urban aquifers. The reasons for this heating are manifold. Possible heat sources are basements of buildings, leakage of sewage systems, buried district heating networks, re-injection of cooling water and solar irradiation on paved surfaces. In the current study, the reported groundwater temperatures in several German cities, such as Berlin, Munich, Cologne and Karlsruhe, are compared. Available data sets are supplemented by temperature measurements and depth profiles in observation wells. Trend analyses are conducted with time series of groundwater temperatures, and three-dimensional groundwater temperature maps are provided. In all investigated cities, pronounced positive temperature anomalies are present. The distribution of groundwater temperatures appears to be spatially and temporally highly variable. Apparently, the increased heat input into the urban subsurface is controlled by very local and site-specific parameters. In the long-run, the superposition of various heat sources results in an extensive temperature increase. In many cases, the maximum temperature elevation is found close to the city centre. Regional groundwater temperature differences between the city centre and the rural background are up to 5 °C, with local hot spots of even more pronounced anomalies. Particular heat sources, like cooling water injections or case-specific underground constructions, can cause local temperatures > 20°C in the subsurface. Examination of the long-term variations in isotherm maps shows that temperatures have increased by about 1°C in the city, as well as in the rural background areas over the last decades. This increase could be reproduced with trend analysis of temperature data gathered from several groundwater wells. Comparison between groundwater and air temperatures in Karlsruhe, for example, also indicates a

The heat shock proteins at the increasing of the radioresistance of silkworm embryo Bombyx Moril

International Nuclear Information System (INIS)

Agaev, F.A.; Garibov, A.A.; Aliev, D.I.; Alieva, I.N.

2002-01-01

The aim of this study is revealing the role of Heat Shock Proteins (HSP) at the radio-modification effect of Heat Shock (HS) on the silkworm embryo. Our preliminary study was indicated that 3-daily silkworm embryo is more than 10-12 times sensitive to gamma-radiation in comparative to 7-daily embryo. Investigation of the HS effect on the radiosensitivity of the embryo indicates that thermal treatment (40 deg. C) of 3 daily embryo during 60 min before irradiation leads the increasing of its radioresistance. At the same time, the HS treatment immediately after irradiation capable increases strike affect of irradiation. LD 50 for heat treated embryo before and after irradiation consists of 46.7 and 19.0 Gy, correspondingly. For embryo irradiated without heat treatment LD 50 is 29.5 Gy. Identical effects are observed for 7-daily embryo. Increasing of the radioresistance by HS before irradiation, obviously, may be explained by the embryo cell reply to the stress factor and capable initiated by different biochemical shifts, for example, by induction of HPS synthesis. According to the results of carried out experiments HS treatment leads to the induction or increasing of the HSP synthesis into this embryo. Protein with molecular mass 70 kDa (HSP-70 kDa) has been synthesised de novo. The synthesis of the other two proteins (HSP-83 kDa and HSP-68 kDa) significantly increases at the high temperature. It is noted, that HSP-70 kDa consists of 55-60 % of whole included radioactive mark. Identical induction was observed in the experiments at the combined effect both HS and gamma-radiation on the embryo. At the post-radiation heat treatment the induction of HSP synthesis is observed, too. It was concluded that damages induced by irradiation can not prevent HSP induction into embryo. The result of comparative analysis was shown that in 3-daily embryo in spite of 7-daily embryo the synthesis of HSP is more intensive and correlated with the radio- modification effect of HS. The

FED, Geometry Input Generator for Program TRUMP

International Nuclear Information System (INIS)

Schauer, D.A.; Elrod, D.C.

1996-01-01

1 - Description of program or function: FED reduces the effort required to obtain the necessary geometric input for problems which are to be solved using the heat-transfer code, TRUMP (NESC 771). TRUMP calculates transient and steady-state temperature distributions in multidimensional systems. FED can properly zone any body of revolution in one, or three dimensions. 2 - Method of solution: The region of interest must first be divided into areas which may consist of a common material. The boundaries of these areas are the required FED input. Each area is subdivided into volume nodes, and the geometrical properties are calculated. Finally, FED connects the adjacent nodes to one another, using the proper surface area, interface distance, and, if specified, radiation form factor and interface conductance. 3 - Restrictions on the complexity of the problem: Rectangular bodies can only be approximated by using a very large radius of revolution compared to the total radial thickness and by considering only a small angular segment in the circumferential direction

Coefficient of Performance Optimization of Single-Effect Lithium-Bromide Absorption Cycle Heat Pumps

DEFF Research Database (Denmark)

Vinther, Kasper; Just Nielsen, Rene; Nielsen, Kirsten Mølgaard

2015-01-01

In this paper, we investigate the coefficient of performance (COP) of a LiBr absorption cycle heat pump under different operating conditions. The investigation is carried out using a dynamical model fitted against data recorded from an actual heat pump used for district heating in S......⊘nderborg, Denmark. Since the model is too complex to study analytically, we vary different input variables within the permissible operating range of the heat pump and evaluate COP at the resulting steady-state operating points. It is found that the best set-point for each individual input is located at an extreme......-state operation of the heat pump, while avoiding crystallization issues....

A computational procedure for finding multiple solutions of convective heat transfer equations

International Nuclear Information System (INIS)

Mishra, S; DebRoy, T

2005-01-01

In recent years numerical solutions of the convective heat transfer equations have provided significant insight into the complex materials processing operations. However, these computational methods suffer from two major shortcomings. First, these procedures are designed to calculate temperature fields and cooling rates as output and the unidirectional structure of these solutions preclude specification of these variables as input even when their desired values are known. Second, and more important, these procedures cannot determine multiple pathways or multiple sets of input variables to achieve a particular output from the convective heat transfer equations. Here we propose a new method that overcomes the aforementioned shortcomings of the commonly used solutions of the convective heat transfer equations. The procedure combines the conventional numerical solution methods with a real number based genetic algorithm (GA) to achieve bi-directionality, i.e. the ability to calculate the required input variables to achieve a specific output such as temperature field or cooling rate. More important, the ability of the GA to find a population of solutions enables this procedure to search for and find multiple sets of input variables, all of which can lead to the desired specific output. The proposed computational procedure has been applied to convective heat transfer in a liquid layer locally heated on its free surface by an electric arc, where various sets of input variables are computed to achieve a specific fusion zone geometry defined by an equilibrium temperature. Good agreement is achieved between the model predictions and the independent experimental results, indicating significant promise for the application of this procedure in finding multiple solutions of convective heat transfer equations

Asymmetric dimethylarginine may mediate increased heat pain threshold in experimental chronic kidney disease.

Science.gov (United States)

Kielstein, Jan T; Suntharalingam, Mayuren; Perthel, Ronny; Rong, Song; Martens-Lobenhoffer, Jens; Jäger, Kristin; Bode-Böger, Stefanie M; Nave, Heike

2012-03-01

Thermal sensitivity in uraemia is decreased. Non-selective synthetic nitric oxide synthase (NOS) inhibitors significantly attenuate thermal hyperalgesia in preclinical models. The aim of our study was to evaluate the effect of experimental uraemia, which is associated with an increase of the endogenous NOS inhibitor asymmetric dimethylarginine (ADMA), on thermal sensitivity in rats. Furthermore, we intended to study the effect of chronic ADMA infusion alone on thermal sensitivity. Male Sprague-Dawley rats (n = 54), 10 weeks old, weight 370-430 g, were randomly assigned to three groups receiving either (i) isotonic saline or (ii) ADMA via osmotic mini pumps or (iii) underwent 5/6 nephrectomy (Nx). After 14 days, 50% of all animals from all groups underwent thermal sensitivity testing and terminal blood draw. After 28 days, the remaining animals underwent the same procedures. Thermal sensitivity examination was performed by the hot-plate test, measuring time from heat exposition to first paw licking or jumping of the animal. While the median [interquartile range] latency time between heat exposition to first paw licking or jumping of the animal in the NaCl infusion group remained unchanged between Day 14 (8.4 [6.75-11.50] s) and Day 28 (7.35 [6.10-7.90] s) both, ADMA infusion and 5/6 nephrectomy tended to increase the thermal pain threshold at Day 14 (9.25 [6.55-12.18] s) and (9.50 [5.8 ± 11.0] s), respectively, compared to NaCl on Day 14 (8.4 [6.75-11.50] s). This difference became statistical significant at Day 28 where the median latency time in the ADMA group (13.10 [11.85-15.95] s) and in the 5/6 Nx group (13.50 [10.85-17.55] s) were significantly higher than in the NaCl group (7.35 [6.10-7.90] s). Induction of progressive renal failure in rats by 5/6 nephrectomy, which is accompanied by a marked increase of the serum levels of the endogenous NOS inhibitor ADMA, leads to a significantly increased heat pain threshold at 28 days. The sole infusion of ADMA into

Adaptive distributed parameter and input estimation in linear parabolic PDEs

KAUST Repository

Mechhoud, Sarra

2016-01-01

In this paper, we discuss the on-line estimation of distributed source term, diffusion, and reaction coefficients of a linear parabolic partial differential equation using both distributed and interior-point measurements. First, new sufficient identifiability conditions of the input and the parameter simultaneous estimation are stated. Then, by means of Lyapunov-based design, an adaptive estimator is derived in the infinite-dimensional framework. It consists of a state observer and gradient-based parameter and input adaptation laws. The parameter convergence depends on the plant signal richness assumption, whereas the state convergence is established using a Lyapunov approach. The results of the paper are illustrated by simulation on tokamak plasma heat transport model using simulated data.

Effect of nitrogen-doped graphene nanofluid on the thermal performance of the grooved copper heat pipe

DEFF Research Database (Denmark)

Mehrali, Mohammad; Sadeghinezhad, Emad; Azizian, Reza

2016-01-01

Thermal performance of a grooved heat pipe using aqueous nitrogen-doped graphene (NDG) nanofluids was analysed. This study in particular focused on the effect of varying NDG nanosheets concentrations, heat pipe inclination angles and input heating powers. The results indicated that the inclination...... observed for NDG nanofluid with concentration of 0.06wt%, inclination angle of θ=90° and a heating power of 120W in comparison to DI-water under the exact same condition. Additionally, the surface temperature distribution was decreased by employing NDG nanosheets, which can in return increase the thermal...... performance of a grooved heat pipe. The present investigation indicated that the thermal performance of the grooved heat pipe can be improved significantly by using NDG nanofluids....

World Input-Output Network.

Directory of Open Access Journals (Sweden)

Federica Cerina

Full Text Available Production systems, traditionally analyzed as almost independent national systems, are increasingly connected on a global scale. Only recently becoming available, the World Input-Output Database (WIOD is one of the first efforts to construct the global multi-regional input-output (GMRIO tables. By viewing the world input-output system as an interdependent network where the nodes are the individual industries in different economies and the edges are the monetary goods flows between industries, we analyze respectively the global, regional, and local network properties of the so-called world input-output network (WION and document its evolution over time. At global level, we find that the industries are highly but asymmetrically connected, which implies that micro shocks can lead to macro fluctuations. At regional level, we find that the world production is still operated nationally or at most regionally as the communities detected are either individual economies or geographically well defined regions. Finally, at local level, for each industry we compare the network-based measures with the traditional methods of backward linkages. We find that the network-based measures such as PageRank centrality and community coreness measure can give valuable insights into identifying the key industries.

Influence of Fuel Meat Porosity on Heat Capacities of Fuel Element Plate U3Si2-Al

International Nuclear Information System (INIS)

Ginting, Aslina Br.; Supardjo; Sutri Indaryati

2007-01-01

Analyze of heat capacities of Al powder, AIMg 2 cladding, U 3 Si 2 powder and PEB U 3 Si 2 -Al with the meat porosity of 4.9; 5.53 ; 6.25 ; 6.95 %; 7.90; 8.66% have been done. Analysis was conducted by using Differential Scanning Calorimeter (DSC) at temperature 30℃ to 450℃ with heating rate 1℃ /minute in Argon gas media. The purpose of analyze is to know the influence of increasing of fuel meat porosity on heat capacities because increasing of percentage of meat porosity will cause degradation the of heat capacities of PEB U 3 Si 2 -Al. Result of analysis showed that the heat capacities of Al powder, AIMg 2 cladding increase by temperature, while heat capacities of U 3 Si 2 powder was stable with increasing of temperature up to 450℃. Analysis of heat capacities toward PEB U 3 Si 2 -Al indicate that increasing of fuel meat porosity of caused degradation of the heat capacities of PEB U 3 Si 2 -Al. Data obtained were expected to serve the purpose of input to fabricator of research reactor fuel in for design of fuel element type silicide with high loading. (author)

Workplace heat stress, health and productivity - an increasing challenge for low and middle-income countries during climate change.

Science.gov (United States)

Kjellstrom, Tord; Holmer, Ingvar; Lemke, Bruno

2009-11-11

Global climate change is already increasing the average temperature and direct heat exposure in many places around the world. To assess the potential impact on occupational health and work capacity for people exposed at work to increasing heat due to climate change. A brief review of basic thermal physiology mechanisms, occupational heat exposure guidelines and heat exposure changes in selected cities. In countries with very hot seasons, workers are already affected by working environments hotter than that with which human physiological mechanisms can cope. To protect workers from excessive heat, a number of heat exposure indices have been developed. One that is commonly used in occupational health is the Wet Bulb Globe Temperature (WBGT). We use WBGT to illustrate assessing the proportion of a working hour during which a worker can sustain work and the proportion of that same working hour that (s)he needs to rest to cool the body down and maintain core body temperature below 38 degrees C. Using this proportion a 'work capacity' estimate was calculated for selected heat exposure levels and work intensity levels. The work capacity rapidly reduces as the WBGT exceeds 26-30 degrees C and this can be used to estimate the impact of increasing heat exposure as a result of climate change in tropical countries. One result of climate change is a reduced work capacity in heat-exposed jobs and greater difficulty in achieving economic and social development in the countries affected by this somewhat neglected impact of climate change.

Load-Dependent Increases in Delay-Period Alpha-Band Power Track the Gating of Task-Irrelevant Inputs to Working Memory

Directory of Open Access Journals (Sweden)

Andrew J. Heinz

2017-05-01

Full Text Available Studies exploring the role of neural oscillations in cognition have revealed sustained increases in alpha-band power (ABP during the delay period of verbal and visual working memory (VWM tasks. There have been various proposals regarding the functional significance of such increases, including the inhibition of task-irrelevant cortical areas as well as the active retention of information in VWM. The present study examines the role of delay-period ABP in mediating the effects of interference arising from on-going visual processing during a concurrent VWM task. Specifically, we reasoned that, if set-size dependent increases in ABP represent the gating out of on-going task-irrelevant visual inputs, they should be predictive with respect to some modulation in visual evoked potentials resulting from a task-irrelevant delay period probe stimulus. In order to investigate this possibility, we recorded the electroencephalogram while subjects performed a change detection task requiring the retention of two or four novel shapes. On a portion of trials, a novel, task-irrelevant bilateral checkerboard probe was presented mid-way through the delay. Analyses focused on examining correlations between set-size dependent increases in ABP and changes in the magnitude of the P1, N1 and P3a components of the probe-evoked response and how such increases might be related to behavior. Results revealed that increased delay-period ABP was associated with changes in the amplitude of the N1 and P3a event-related potential (ERP components, and with load-dependent changes in capacity when the probe was presented during the delay. We conclude that load-dependent increases in ABP likely play a role in supporting short-term retention by gating task-irrelevant sensory inputs and suppressing potential sources of disruptive interference.

The DIRT on Q10: In situ depletion of labile-inputs does not increase temperature sensitivity in a laboratory incubation (Invited)

Science.gov (United States)

Reynolds, L. L.; Lajtha, K.; Bowden, R.; Johnson, B. R.; Bridgham, S. D.

2013-12-01

The decomposition of soil organic matter is expected to increase with global warming and has been commonly described by kinetic models with at least two pools with differing turnover times. Pools characterized by rapid turnover are thought to consist of labile substrates. Meanwhile, slower turnover is attributed, in part, to greater chemical complexity and a necessarily higher activation energy which should in turn lead to a higher sensitivity (Q10) to temperature and a proportionally larger response to warming. Experimental tests of the relative Q10 of these pools have been inconclusive and contradictory in part due the fact that all pools are decomposing simultaneously and soils kept under differing conditions over long periods of time diverge in more than the Q10 response making them less comparable over time. We present here a test of the temperature response on soils from a 20 yr litter manipulation experiment incubated under an experimental regime that minimizes divergence among the soils. We hypothesize that 1) if exclusion of inputs has depleted labile substrates and 2) the remaining carbon is more chemically complex, then the input exclusion treatments should show a higher Q10 compared to the ambient or increased input treatments. The soils are taken from the Detritus Input and Removal Treatment (DIRT) plots in the Bousson Forest, Pennsylvania, US. The DIRT treatments consist of litter and root exclusion (no inputs = NI), no roots (NR), no litter (NL), double litter (DL), and ambient conditions (C). Soils were incubated at 25oC for 525 days. Periodically, replicate sets were rotated into 15oC, 35oC or remained at 25oC for 24 hr. The headspace CO2 concentration was measured before and after the 24 hr temperature treatments, and then all replicate sets were returned to 25oC. Twenty years of input exclusion decreased respiration rate, with NI DIRT treatments, despite the clear differences in their carbon pools. Similar studies have examined the temperature

Exogenous Cytokinins Increase Grain Yield of Winter Wheat Cultivars by Improving Stay-Green Characteristics under Heat Stress.

Directory of Open Access Journals (Sweden)

Dongqing Yang

Full Text Available Stay-green, a key trait of wheat, can not only increase the yield of wheat but also its resistance to heat stress during active photosynthesis. Cytokinins are the most potent general coordinator between the stay-green trait and senescence. The objectives of the present study were to identify and assess the effects of cytokinins on the photosynthetic organ and heat resistance in wheat. Two winter wheat cultivars, Wennong 6 (a stay-green cultivar and Jimai 20 (a control cultivar, were subjected to heat stress treatment from 1 to 5 days after anthesis (DAA. The two cultivars were sprayed daily with 10 mg L-1 of 6-benzylaminopurine (6-BA between 1 and 3 DAA under ambient and elevated temperature conditions. We found that the heat stress significantly decreased the number of kernels per spike and the grain yield (P < 0.05. Heat stress also decreased the zeatin riboside (ZR content, but increased the gibberellin (GA3, indole-3-acetic acid (IAA, and abscisic acid (ABA contents at 3 to 15 DAA. Application of 6-BA significantly (P < 0.05 increased the grain-filling rate, endosperm cell division rate, endosperm cell number, and 1,000-grain weight under heated condition. 6-BA application increased ZR and IAA contents at 3 to 28 DAA, but decreased GA3 and ABA contents. The contents of ZR, ABA, and IAA in kernels were positively and significantly correlated with the grain-filling rate (P < 0.05, whereas GA3 was counter-productive at 3 to 15 DAA. These results suggest that the decrease in grain yield under heat stress was due to a lower ZR content and a higher GA3 content compared to that at elevated temperature during the early development of the kernels, which resulted in less kernel number and lower grain-filling rate. The results also provide essential information for further utilization of the cytokinin substances in the cultivation of heat-resistant wheat.

Residual stresses and their mechanisms of production at circumferential weld by heat-sink welding

International Nuclear Information System (INIS)

Ueda, Yukio; Nakacho, Keiji; Ohkubo, Katsumi; Shimizu, Tsubasa.

1983-01-01

In the previous report, the authors showed effectiveness of the heat-sink welding (water cooling) to accomplish this end by conducting theoretical analysis and an experiment on residual stresses in the 4B pipe of SUS 304 by the conventional welding and the heat-sink welding at a certain standard heat-input condition. In this research, different pipe sizes and varied heat-input are applied. The welding residual stresses by the conventional welding and the heat-sink welding are obtained by the theoretical analysis and their production mechanisms are clarified. Hence the influence of the above changes of conditions on effectiveness of the heat-sink welding is investigated. The main results are summarized as follow. (1) In case of this pipes such as 2B and 4B pipes, it is important to minimize heat-input per one pass (especially for latter half passes) in order to improve the effectiveness of the heat-sink welding. The effectiveness can be predicted either by theoretical analysis of the temperature distribution history with consideration of the characteristic of heat transfer under spray-watering or by experimental measurement. (2) In case of 24B pipes, thick pipes, it is desirable to minimize heat-input for the first half passes, by which the heat-sink welding becomes more effective. In addition, no matter whether the conventional welding or the heat-sink welding, it is important to prevent angular distorsion which produces tensile axial stresses on the inner surface of the pipe in the weld zone. Possible measures to meet these requirements are to apply restraining jigs, to minimize the section area of the groove (ex. application of the narrow gap arc welding), and to change continuous welding to skip one. (J.P.N.)

Microstructural response to heat affected zone cracking of prewelding heat-treated Inconel 939 superalloy

Energy Technology Data Exchange (ETDEWEB)

Gonzalez, M.A., E-mail: mgonzalez@comimsa.com.mx [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Martinez, D.I., E-mail: dorairma@yahoo.com [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Perez, A., E-mail: betinperez@hotmail.com [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Guajardo, H., E-mail: hguajardo@frisa.com [FRISA Aerospace, S.A. de C.V., Valentin G. Rivero No. 200, Col. Los Trevino, C.P. 66150, Santa Caterina N.L. (Mexico); Garza, A., E-mail: agarza@comimsa.com [Corporacion Mexicana de Investigacion en Materiales S.A. de C.V. (COMIMSA), Ciencia y Tecnologia No.790, Saltillo 400, C.P. 25295 Saltillo Coah. (Mexico)

2011-12-15

The microstructural response to cracking in the heat-affected zone (HAZ) of a nickel-based IN 939 superalloy after prewelding heat treatments (PWHT) was investigated. The PWHT specimens showed two different microstructures: 1) spherical ordered {gamma} Prime precipitates (357-442 nm), with blocky MC and discreet M{sub 23}C{sub 6} carbides dispersed within the coarse dendrites and in the interdendritic regions; and 2) ordered {gamma} Prime precipitates in 'ogdoadically' diced cube shapes and coarse MC carbides within the dendrites and in the interdendritic regions. After being tungsten inert gas welded (TIG) applying low heat input, welding speed and using a more ductile filler alloy, specimens with microstructures consisting of spherical {gamma} Prime precipitate particles and dispersed discreet MC carbides along the grain boundaries, displayed a considerably improved weldability due to a strong reduction of the intergranular HAZ cracking associated with the liquation microfissuring phenomena. - Highlights: Black-Right-Pointing-Pointer Homogeneous microstructures of {gamma} Prime spheroids and discreet MC carbides of Ni base superalloys through preweld heat treatments. Black-Right-Pointing-Pointer {gamma} Prime spheroids and discreet MC carbides reduce the intergranular HAZ liquation and microfissuring of Nickel base superalloys. Black-Right-Pointing-Pointer Microstructure {gamma} Prime spheroids and discreet blocky type MC carbides, capable to relax the stress generated during weld cooling. Black-Right-Pointing-Pointer Low welding heat input welding speeds and ductile filler alloys reduce the HAZ cracking susceptibility.

Method of increased bioethanol concentration with reduced heat consumption

International Nuclear Information System (INIS)

Bremers, G.; Blija, A.

2003-01-01

Ethanol dehydration applying method of non-reflux saline distillation was conduced on a laboratory scale and in bigger pilot equipment. Results make possible recommend new method for the increased of ethanol concentration. Heat consumption reduced by 50% and cooling water consumption by 90 % when the non-reflux distillation was applied. Reflux flow in the column is replacing with contact mass, which consist from saline layer and seclude medium. Basis diagram of ethanol non-reflux saline distillation was established. Distillation equipment and number of plates in the column can calculate using basis diagram. Absolute ethanol can obtain with non-reflux saline distillation. Absolute ethanol use in produce of biofuel (author)

Optimization of Heat Exchangers

International Nuclear Information System (INIS)

Catton, Ivan

2010-01-01

The objective of this research is to develop tools to design and optimize heat exchangers (HE) and compact heat exchangers (CHE) for intermediate loop heat transport systems found in the very high temperature reator (VHTR) and other Generation IV designs by addressing heat transfer surface augmentation and conjugate modeling. To optimize heat exchanger, a fast running model must be created that will allow for multiple designs to be compared quickly. To model a heat exchanger, volume averaging theory, VAT, is used. VAT allows for the conservation of mass, momentum and energy to be solved for point by point in a 3 dimensional computer model of a heat exchanger. The end product of this project is a computer code that can predict an optimal configuration for a heat exchanger given only a few constraints (input fluids, size, cost, etc.). As VAT computer code can be used to model characteristics (pumping power, temperatures, and cost) of heat exchangers more quickly than traditional CFD or experiment, optimization of every geometric parameter simultaneously can be made. Using design of experiment, DOE and genetric algorithms, GE, to optimize the results of the computer code will improve heat exchanger design.

Experimental Study of Single Phase Flow in a Closed-Loop Cooling System with Integrated Mini-Channel Heat Sink

Directory of Open Access Journals (Sweden)

Lei Ma

2016-06-01

Full Text Available The flow and heat transfer characteristics of a closed-loop cooling system with a mini-channel heat sink for thermal management of electronics is studied experimentally. The heat sink is designed with corrugated fins to improve its heat dissipation capability. The experiments are performed using variable coolant volumetric flow rates and input heating powers. The experimental results show a high and reliable thermal performance using the heat sink with corrugated fins. The heat transfer capability is improved up to 30 W/cm2 when the base temperature is kept at a stable and acceptable level. Besides the heat transfer capability enhancement, the capability of the system to transfer heat for a long distance is also studied and a fast thermal response time to reach steady state is observed once the input heating power or the volume flow rate are varied. Under different input heat source powers and volumetric flow rates, our results suggest potential applications of the designed mini-channel heat sink in cooling microelectronics.

History of nutrient inputs to the northeastern United States, 1930-2000

Science.gov (United States)

Hale, Rebecca L.; Hoover, Joseph H.; Wollheim, Wilfred M.; Vörösmarty, Charles J.

2013-04-01

Humans have dramatically altered nutrient cycles at local to global scales. We examined changes in anthropogenic nutrient inputs to the northeastern United States (NE) from 1930 to 2000. We created a comprehensive time series of anthropogenic N and P inputs to 437 counties in the NE at 5 year intervals. Inputs included atmospheric N deposition, biological N2 fixation, fertilizer, detergent P, livestock feed, and human food. Exports included exports of feed and food and volatilization of ammonia. N inputs to the NE increased throughout the study period, primarily due to increases in atmospheric deposition and fertilizer. P inputs increased until 1970 and then declined due to decreased fertilizer and detergent inputs. Livestock consistently consumed the majority of nutrient inputs over time and space. The area of crop agriculture declined during the study period but consumed more nutrients as fertilizer. We found that stoichiometry (N:P) of inputs and absolute amounts of N matched nutritional needs (livestock, humans, crops) when atmospheric components (N deposition, N2 fixation) were not included. Differences between N and P led to major changes in N:P stoichiometry over time, consistent with global trends. N:P decreased from 1930 to 1970 due to increased inputs of P, and increased from 1970 to 2000 due to increased N deposition and fertilizer and decreases in P fertilizer and detergent use. We found that nutrient use is a dynamic product of social, economic, political, and environmental interactions. Therefore, future nutrient management must take into account these factors to design successful and effective nutrient reduction measures.

Fish culture in heated effluents (eastern Europe). [Growth increase in carp and rainbow trout

Energy Technology Data Exchange (ETDEWEB)

Backiel, T; Gay, B; La Croix, M J.B.; Ophel, I L [eds.

1976-01-01

Dependence of growth and reproduction of cultivated fishes on temperature are briefly reviewed. Experiments with and commercial-size operations of various methods of fish culture with the use of heated effluents are exemplified. Cage culture, earthen ponds, flowing water culture have demonstrated possibilities of growth increase in carp and rainbow trout and of controlled reproduction of the former. Problems involved in utilization of various systems and several points of view on the use of low-grade heat for fish culture are considered.

Low grade waste heat recovery using heat pumps and power cycles

International Nuclear Information System (INIS)

Bor, D.M. van de; Infante Ferreira, C.A.; Kiss, Anton A.

2015-01-01

Thermal energy represents a large part of the global energy usage and about 43% of this energy is used for industrial applications. Large amounts are lost via exhaust gases, liquid streams and cooling water while the share of low temperature waste heat is the largest. Heat pumps upgrading waste heat to process heat and cooling and power cycles converting waste heat to electricity can make a strong impact in the related industries. The potential of several alternative technologies, either for the upgrading of low temperature waste heat such as compression-resorption, vapor compression and trans-critical heat pumps, or for the conversion of this waste heat by using organic Rankine, Kalina and trilateral cycle engines, are investigated with regards to energetic and economic performance by making use of thermodynamic models. This study focuses on temperature levels of 45–60 °C as at this temperature range large amounts of heat are rejected to the environment but also investigates the temperature levels for which power cycles become competitive. The heat pumps deliver 2.5–11 times more energy value than the power cycles in this low temperature range at equal waste heat input. Heat engines become competitive with heat pumps at waste heat temperatures at 100 °C and above. - Highlights: • Application of heat pump technology for heating and cooling. • Compression resorption heat pumps operating with large glides approaching 100 K. • Compression-resorption heat pumps with wet compression. • Potential to convert Industrial waste heat to power or high grade heat. • Comparison between low temperature power cycles and heat pumps

Transient heat transfer in liquid helium

International Nuclear Information System (INIS)

Shiotsu, Masahiro

1991-01-01

Detailed knowledge on the steady-state and transient heat transfer from solid surfaces in He I and He II is important as a database for the analysis of the influence of local thermal disturbances on the stability of He I or He II cooled large superconducting magnets. In this paper, an overview of the transient heat transfer characteristics on solid surfaces in He I and He II caused by various large stepwise heat inputs, such as the quasi-steady nucleate boiling with a certain lifetime in He I and the quasi-steady Kapitza conductance heat flux with a certain lifetime in He II, are presented in comparison with their steady-state heat transfer characteristics. (author)

Improvements of reforming performance of a nuclear heated steam reforming process

International Nuclear Information System (INIS)

Hada, Kazuhiko

1996-10-01

Performance of an energy production process by utilizing high temperature nuclear process heat was not competitive to that by utilizing non-nuclear process heat, especially fossil-fired process heat due to its less favorable chemical reaction conditions. Less favorable conditions are because a temperature of the nuclear generated heat is around 950degC and the heat transferring fluid is the helium gas pressurized at around 4 MPa. Improvements of reforming performance of nuclear heated steam reforming process were proposed in the present report. The steam reforming process, one of hydrogen production processes, has the possibility to be industrialized as a nuclear heated process as early as expected, and technical solutions to resolve issues for coupling an HTGR with the steam reforming system are applicable to other nuclear-heated hydrogen production systems. The improvements are as follows: As for the steam reformer, (1) increase in heat input to process gas by applying a bayonet type of reformer tubes and so on, (2) increase in reforming temperature by enhancing heat transfer rate by the use of combined promoters of orifice baffles, cylindrical thermal radiation pipes and other proposal, and (3) increase in conversion rate of methane to hydrogen by optimizing chemical compositions of feed process gas. Regarding system arrangement, a steam generator and superheater are set in the helium loop as downstream coolers of the steam reformer, so as to effectively utilize the residual nuclear heat for generating feed steam. The improvements are estimated to achieve the hydrogen production rate of approximately 3800 STP-m 3 /h for the heat source of 10 MW and therefore will provide the potential competitiveness to a fossil-fired steam reforming process. Those improvements also provide the compactness of reformer tubes, giving the applicability of seamless tubes. (J.P.N.)

Opening of the markets increases the risks of district heating business

International Nuclear Information System (INIS)

Silvennoinen, A.

2001-01-01

Maintenance of the technical operation conditions of district heating is the main requirement of community to the district heating business. Infrastructure of district heating, including the heat generation and distribution plants, equipment and devices, requires relatively large investments. Total process from fuel purchase to heat delivery does not occur in a closed limited area, but it penetrates the total market area (heat distribution network) and even larger via fuel purchase and transport. E.g. the fuels are combustible and might explode. Oil-spills into the environment may have catastrophic effects. Large leakage of hot district heating water is both environmentally hazardous and forms also a health hazard, and they stop the delivery of district heat. Dominant position on the markets is also followed closely by the authorities. On the other hand competition with other heating forms require efficient operation. The author reviews in the article the basics of risk management, and especially in the district heating business. The risk management process is discussed in the risk analysis and determination of the significance of the risks, the effects of realization of the risks, planning of the measures to be taken to avoid risks, and preparations against the risks

National conference on centralized heat supply from heat feeders in selected localities

International Nuclear Information System (INIS)

1990-05-01

The proceedings contain 8 contributions, out of which 5 have been inputted in INIS. These deal with centralized heat supply systems, hydraulic and thermal parameters of the hot water distribution systems, and the feasibility of including nuclear sources into the systems. Treated are both actual systems and calculation models. (B.S.)

Increase in the free radical scavenging capability of bitter gourd by a heat-drying process.

Science.gov (United States)

Wei, Lu; Shaoyun, Wang; Shutao, Liu; Jianwu, Zhou; Lijing, Ke; Pingfan, Rao

2013-12-01

Bitter gourd (Momordica charantia Linn.) is widely regarded as one of the best remedy foods for diabetes. The positive effect of bitter gourd on diabetes has been attributed in part to the remarkable free radical scavenging activity of its boiled water extract from sun-dried fruits. It is well known that a heat process significantly influences the antioxidant activity of fresh fruits. However, the heat drying processes of bitter gourd have not been studied so far. Here, we show that the free radical scavenging capability of bitter gourd extract significantly increases after the heat drying process, while the content of flavonoids and phenols, which are generally regarded as the main antioxidant components in bitter gourd, remain unaffected. Furthermore, the content of free amino acids and the total reducing sugar were found to decrease with increasing browning index, indicating the progression of the Maillard reaction, products of which are known to possess significant antioxidant activity. Therefore, it suggests that Maillard reaction products may be the main contributors to the increase in antioxidant capability. Finally, the bitter gourd extract with the higher antioxidant activity, was shown to manifest a corresponding higher proliferation activity on NIT-1 beta-cells. These results suggest that controllable conditions in the heat-drying processing of fresh bitter gourd fruit is of significance for enhancing the total free radical scavenging capacity, beta-cell proliferation activity and possibly the anti-diabetic activity of this fruit.

Increased Heat Generation in Postcardiac Arrest Patients During Targeted Temperature Management Is Associated With Better Outcomes.

Science.gov (United States)

Uber, Amy J; Perman, Sarah M; Cocchi, Michael N; Patel, Parth V; Ganley, Sarah E; Portmann, Jocelyn M; Donnino, Michael W; Grossestreuer, Anne V

2018-04-03

relationship between outcomes and time to Ttarget was no longer significant. Controlling for location, witnessed arrest, age, initial rhythm, and neuromuscular blockade use, increased heat generation was associated with better neurologic (adjusted odds ratio, 1.01 [95% CI, 1.00-1.03]; p = 0.039) and survival (adjusted odds ratio, 1.01 [95% CI, 1.00-1.03]; p = 0.045) outcomes. Increased heat generation during targeted temperature management initiation is associated with better outcomes at hospital discharge and may affect the relationship between time to Ttarget and outcomes.

Analysis of heating effect on the process of high deposition rate microcrystalline silicon

International Nuclear Information System (INIS)

Xiao-Dan, Zhang; He, Zhang; Chang-Chun, Wei; Jian, Sun; Guo-Fu, Hou; Shao-Zhen, Xiong; Xin-Hua, Geng; Ying, Zhao

2010-01-01

A possible heating effect on the process of high deposition rate microcrystalline silicon has been studied. It includes the discharge time-accumulating heating effect, discharge power, inter-electrode distance, and total gas flow rate induced heating effect. It is found that the heating effects mentioned above are in some ways quite similar to and in other ways very different from each other. However, all of them will directly or indirectly cause the increase of the substrate surface temperature during the process of depositing microcrystalline silicon thin films, which will affect the properties of the materials with increasing time. This phenomenon is very serious for the high deposition rate of microcrystalline silicon thin films because of the high input power and the relatively small inter-electrode distance needed. Through analysis of the heating effects occurring in the process of depositing microcrystalline silicon, it is proposed that the discharge power and the heating temperature should be as low as possible, and the total gas flow rate and the inter-electrode distance should be suitable so that device-grade high quality deposition rate microcrystalline silicon thin films can be fabricated

Analysis of a combined heating and cooling system model under different operating strategies

Science.gov (United States)

Dzierzgowski, Mieczysław; Zwierzchowski, Ryszard

2017-11-01

The paper presents an analysis of a combined heating and cooling system model under different operating strategies. Cooling demand for air conditioning purposes has grown steadily in Poland since the early 1990s. The main clients are large office buildings and shopping malls in downtown locations. Increased demand for heat in the summer would mitigate a number of problems regarding District Heating System (DHS) operation at minimum power, affecting the average annual price of heat (in summertime the share of costs related to transport losses is a strong cost factor). In the paper, computer simulations were performed for different supply network water temperature, assuming as input, real changes in the parameters of the DHS (heat demand, flow rates, etc.). On the basis of calculations and taking into account investment costs of the Absorption Refrigeration System (ARS) and the Thermal Energy Storage (TES) system, an optimal capacity of the TES system was proposed to ensure smooth and efficient operation of the District Heating Plant (DHP). Application of ARS with the TES system in the DHS in question increases net profit by 19.4%, reducing the cooling price for consumers by 40%.

On the material properties of shell plate formed by line heating

Directory of Open Access Journals (Sweden)

Hyung Kyun Lim

2017-01-01

Full Text Available This paper is concerned with investigating the plastic material properties of steel plate formed by line heating method, and is aimed at implementing more rational design considering the accidental limit states such as collision or grounding. For the present study, line heating test for marine grade steel plate has been carried out with varying plate thickness and heating speed, and then microscopic examination and tensile test have been carried out. From the microscopic, it is found that the grain refined zones like ferrite and pearlite are formed all around the heat affected zone. From the tensile test results, it is seen that yield strength, tensile strength, fracture strain, hardening exponent and strength coefficient vary with plate thickness and heat input quantity. The formulae relating the material properties and heat input parameter should be, therefore, derived for the design purpose considering the accidental impact loading. This paper ends with describing the extension of the present study.

Heat pipe heat exchangers in heat recovery systems

Energy Technology Data Exchange (ETDEWEB)

Stulc, P; Vasiliev, L L; Kiseljev, V G; Matvejev, Ju N

1985-01-01

The results of combined research and development activities of the National Research Institute for Machine Design, Prague, C.S.S.R. and the Institute for Heat and Mass Transfer, Minsk, U.S.S.R. concerning intensification heat pipes used in heat pipe heat exchangers are presented. This sort of research has been occasioned by increased interest in heat power economy trying to utilise waste heat produced by various technological processes. The developed heat pipes are deployed in construction of air-air, gas-air or gas-gas heat recovery exchangers in the field of air-engineering and air-conditioning. (author).

District heating for increased biogas production. Technical and economical evaluation of district heating as heating source in biogas processes; Fjaerrvaerme foer utoekad biogasproduktion. Teknisk och ekonomisk utvaerdering av fjaerrvaerme foer uppvaermning av biogasprocesser

Energy Technology Data Exchange (ETDEWEB)

Lundqvist, Per (AaF-Consult AB, Stockholm (Sweden))

2009-11-15

This report presents a technical evaluation, the potential and an economical evaluation of the increased net biogas production by using district heating as energy supply for different types of biogas production units. The study presents generalized results for different plant sizes. The district heating is considered as replacement of the heat produced by burning biogas in a hot-water boiler. Hence more biogas could be available for upgrading to fuel-gas quality to be used in vehicles as a renewable fuel. The study is aimed at biogas producers, district heating and combined heat and power (CHP) companies. Biogas has a composition of mostly methane (about 65 %) and carbon dioxide (about 35 %) and small amounts of other gases e.g. sulphur dioxide (H{sub 2}S). Biogas up-grading is a process where the methane content is increased to about 97 % by removing most of the other gases in e.g. an absorption unit. The Swedish biogas is mainly produced in several sewage treatment plants and some co-digestion units but is also collected from dumps. Biogas is produced by anaerobic microorganisms at temperatures of about 36 and 55 deg C which correspond to the thermal optimum for mesophile and thermophile bacteria respectively. Co-digestion of animal material which e.g. is contained in collected organic household waste has to be pasteurized at 70 deg C for 1h according to EU-regulations. Such regulations may also be introduced to the sludge from municipal sewage treatment plants. Due to the fact that the process temperature is higher than the temperature of the substrate (sludge or organic waste material) as well as the outdoor temperature, both heating of the incoming substrate and compensation of heat losses are required. Traditionally most of the biogas has been burnt to generate the necessary heat for the process and premises at the plant. The excess gas has been burnt in a torch. In recent years the biogas produced in Sweden has found increased use as a renewable vehicle fuel

Characteristics of ion Bernstein wave heating in JIPPT-II-U tokamak

International Nuclear Information System (INIS)

Okamoto, M.; Ono, M.

1985-11-01

Using a transport code combined with an ion Bernstein wave tokamak ray tracing code, a modelling code for the ion Bernstein wave heating has been developed. Using this code, the ion Bernstein wave heating experiment on the JIPPT-II-U tokamak has been analyzed. It is assumed that the resonance layer is formed by the third harmonic of deuterium-like ions, such as fully ionized carbon, and oxygen ions near the plasma center. For wave absorption mechanisms, electron Landau damping, ion cyclotron harmonic damping, and collisional damping are considered. The characteristics of the ion Bernstein wave heating experiment, such as the ion temperature increase, the strong dependence of the quality factor on the magnetic field strength, and the dependence of the ion temperature increment on the input power, are well reproduced

Development of hybrid solar-assisted cooling/heating system

KAUST Repository

Huang, B.J.; Wu, J.H.; Hsu, H.Y.; Wang, J.H.

2010-01-01

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.

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.

Experimental investigation of the effects of orientation angle on heat transfer performance of pin-finned surfaces in natural convection

International Nuclear Information System (INIS)

Sertkaya, Ahmet Ali; Bilir, Sefik; Kargici, Suna

2011-01-01

Natural convection heat transfer in air from a pin-finned surface is investigated experimentally by considering the effect of radiation heat transfer. The plate was oriented as the pin arrays facing either downwards or upwards from vertical axis with different angles and the experiments were performed for different values of heater power input. From the results of the experiments it is observed that the pin fins increase the heat transfer considerably when compared to the unpinned surface. The upfacing pins are more enhancing heat transfer than the downfacing pins and the enhancement is decreasing with increasing orientation angle from the vertical axis. -- Research highlights: → Effect of orientation in free convection heat transfer from a pin-finned surface. → The upfacing pins are more enhancing heat transfer than the downfacing pins. → Radiation view factor is calculated by a modular analysis. → The radiation is comparable to free convection as not to be neglected. → The radiative part is 25-40% and increases for low heat transfer rates.

Workplace heat stress, health and productivity – an increasing challenge for low and middle-income countries during climate change

Science.gov (United States)

Kjellstrom, Tord; Holmer, Ingvar; Lemke, Bruno

2009-01-01

Background Global climate change is already increasing the average temperature and direct heat exposure in many places around the world. Objectives To assess the potential impact on occupational health and work capacity for people exposed at work to increasing heat due to climate change. Design A brief review of basic thermal physiology mechanisms, occupational heat exposure guidelines and heat exposure changes in selected cities. Results In countries with very hot seasons, workers are already affected by working environments hotter than that with which human physiological mechanisms can cope. To protect workers from excessive heat, a number of heat exposure indices have been developed. One that is commonly used in occupational health is the Wet Bulb Globe Temperature (WBGT). We use WBGT to illustrate assessing the proportion of a working hour during which a worker can sustain work and the proportion of that same working hour that (s)he needs to rest to cool the body down and maintain core body temperature below 38°C. Using this proportion a ‘work capacity’ estimate was calculated for selected heat exposure levels and work intensity levels. The work capacity rapidly reduces as the WBGT exceeds 26–30°C and this can be used to estimate the impact of increasing heat exposure as a result of climate change in tropical countries. Conclusions One result of climate change is a reduced work capacity in heat-exposed jobs and greater difficulty in achieving economic and social development in the countries affected by this somewhat neglected impact of climate change. PMID:20052422

Pump/heat exchanger assembly for pool-type reactor

International Nuclear Information System (INIS)

Nathenson, R.D.; Slepian, R.M.

1989-01-01

This patent describes a heat exchanger and pump assembly for transferring thermal energy from a heated, first electrically conductive fluid to a pumped, second electrically conductive fluid and for transferring internal energy from the pumped, second electrically conductive fluid to the first electrically conductive fluid, the assembly adapted to be disposed within a pool of the first electrically conductive fluid and comprising: a heat exchanger comprising means for defining a first annularly shaped cavity for receiving a flow of the second electrically conductive fluid and a plurality of tubes disposed within the cavity, whereby the second electrically conductive fluid in the cavity is heated, each of the tubes having an input and an output end. The input ends being disposed at the top of the heat exchanger for receiving from the pool a flow of the first electrically conductive fluid therein. The output ends being disposed at the bottom of and free of the cavity defining means for discharging the first electrically conductive fluid directly into the pool; a pump disposed beneath the heat exchanger and comprised of a plurality of flow couplers disposed in a circular array, each flow coupler comprised of a pump duct for receiving the first electrically conductive fluid and a generator duct for receiving the second electrically conductive fluid

Multi-Input Convolutional Neural Network for Flower Grading

Directory of Open Access Journals (Sweden)

Yu Sun

2017-01-01

Full Text Available Flower grading is a significant task because it is extremely convenient for managing the flowers in greenhouse and market. With the development of computer vision, flower grading has become an interdisciplinary focus in both botany and computer vision. A new dataset named BjfuGloxinia contains three quality grades; each grade consists of 107 samples and 321 images. A multi-input convolutional neural network is designed for large scale flower grading. Multi-input CNN achieves a satisfactory accuracy of 89.6% on the BjfuGloxinia after data augmentation. Compared with a single-input CNN, the accuracy of multi-input CNN is increased by 5% on average, demonstrating that multi-input convolutional neural network is a promising model for flower grading. Although data augmentation contributes to the model, the accuracy is still limited by lack of samples diversity. Majority of misclassification is derived from the medium class. The image processing based bud detection is useful for reducing the misclassification, increasing the accuracy of flower grading to approximately 93.9%.

Experimental investigation on thermal performance of a closed loop pulsating heat pipe (CLPHP) using methanol and distilled water at different filling ratios

Science.gov (United States)

Rahman, Md. Lutfor; Swarna, Anindita Dhar; Ahmed, Syed Nasif Uddin; Perven, Sanjida; Ali, Mohammad

2016-07-01

Pulsating Heat Pipes, the new two-phase heat transfer devices, with no counter current flow between liquid and vapor have become a modern topic for research in the field of thermal management. This paper focuses on the performance of methanol and distilled water as working fluid in a closed loop pulsating heat pipe (CLPHP). This performances are compared in terms of thermal resistance, heat transfer co-efficient, and evaporator and condenser wall temperature with variable heat inputs. Methanol and Distilled water are selected for their lower surface tension, dynamic viscosity and sensible heat. A closed loop PHP made of copper with 2mm ID and 2.5mm OD having total 8 loops are supplied with power input varied from 10W to 60W. During the experiment the PHP is kept vertical, while the filling ratio (FR) is increased gradually from 40% to 70% with 10% increment. The optimum filling ratio for a minimum thermal resistance is found to be 60% and 40% for distilled water and methanol respectively and methanol is found to be the better working fluid compared to distilled water in terms of its lower thermal resistance and higher heat transfer coefficient.

Economic and environmental efficiency of district heating plants

DEFF Research Database (Denmark)

Agrell, Per J.; Bogetoft, Peter

2005-01-01

heat, have arbitrary valuation.This study concerns the most developed European district heating and cogeneration system, the Danish.By assessing environmental and economic ef¿ciency, the impact of governmental, market and managerial imperfections are estimated.The principal methodological base......District heating, the conversion of primary energy into distributed thermal energy and possible electric energy, is a challenge to regulate.In addition to the ever present asymmetric information in any suf¿ciently complex activity, some of the inputs for district heating, such as excess process...

Heat accumulation between scans during multi-pass cutting of carbon fiber reinforced plastics

Science.gov (United States)

Kononenko, T. V.; Freitag, C.; Komlenok, M. S.; Weber, R.; Graf, T.; Konov, V. I.

2018-02-01

Matrix evaporation caused by heat accumulation between scans (HAS) was studied in the case of multi-pass scanning of a laser beam over the surface of carbon fiber reinforced plastic (CFRP). The experiments were performed in two regimes, namely, in the process of CFRP cutting and in the regime of low-fluence irradiation avoiding ablation of carbon fibers. The feature of the ablation-free regime is that all absorbed energy remains in the material as heat, while in the cutting regime the fraction of residual heat is unknown. An analytical model based on two-dimensional (2D) heat flow was applied to predict the critical number of scans, after which the HAS effect causes a distinct growth of the matrix evaporation zone (MEZ). According to the model, the critical number of scans decreases exponentially with increasing laser power, while no dependence on the feed rate is expected. It was found that the model fits well to the experimental data obtained in the ablation-free regime where the heat input is well defined and known. In the cutting regime the measured significant reduction of the critical number of scans observed in deep grooves may be attributed to transformation of the heat flow geometry and to an expected increase of the residual heat fraction.

Simulations and experiments of laminar heat transfer for Therminol heat transfer fluids in a rifled tube

International Nuclear Information System (INIS)

Xu, Weiguo; Ren, Depeng; Ye, Qing; Liu, Guodong; Lu, Huilin; Wang, Shuai

2016-01-01

Graphical abstract: Predicted laminar Nusselt number using regression correlation of Therminol-55 heat transfer fluid is in agreement with experiments in the rifled tube. - Highlights: • Heat transfer coefficient and friction factor are measured and predicted in the rifled tube. • Correlations for Nusselt number and friction factor are proposed. • The roughness height of 0.425 mm in transition SST model is suggested as an input parameter. • k–kl–ω transition and transition SST models are recommended for laminar–turbulent transition. • Thermal enhancement factor and synergy angle are predicted in the rifled tube. - Abstract: Simulations and experiments of flow and heat transfer behavior of Therminol-55 heat transfer fluid have been conducted in a horizontal rifled tube with outer diameter and inner diameter 25.0 and 20.0 mm, pitch and rib height of 12.0 and 1.0 mm, respectively. Numerical simulations of three-dimensional flow behavior of Therminol-55 heat transfer fluid are carried out using FLUENT code in the rifled tube. Experimental results show that the heat transfer and thermal performance of Therminol-55 heat transfer fluid in the rifled tube are considerably improved compared to those of the smooth tube. The Nusselt number increases with the increase of Reynolds number, and is from 3.5 to 5.1 times over the smooth tube. Also, the pressure drop results reveal that the average friction factor of the ribbed tube is in a range of 2.2 and 4.2 times over the smooth tube. Predictive Nusselt number and friction factor correlations have been presented. The numerical results show that the laminar flow model is valid only at lower Reynolds number in the developed laminar flow of rifled tube. The k–kl–ω transition model and transition SST model with roughness of 0.425 mm are recommended for the predictions of transition process from laminar to turbulent flow in the rifled tube.

Subcooled He II heat transport in the channel with abrupt contractions/enlargements

International Nuclear Information System (INIS)

Maekawa, R.; Iwamoto, A.; Hamaguchi, S.; Mito, T.

2002-01-01

Heat transport mechanisms for subcooled He II in the channel with abrupt contractions and/or enlargements have been investigated under steady state conditions. The channel, made of G-10, contains various contraction geometries to simulate the cooling channel of a superconducting magnet. In other words, contractions are periodically placed along the channel to simulate the spacers within the magnet winding. A copper block heater inputs the heat to the channel from one end, while the other end is open to the He II bath. Temperature profiles were measured with temperature sensors embedded in the channel as a function of heat input. Calculations were performed using a simple one-dimensional turbulent heat transport equation and with geometric factor consideration. The effects on heat transport mechanisms in He II caused by abrupt change of channel geometry and size are discussed

Exposure to extreme heat and precipitation events associated with increased risk of hospitalization for asthma in Maryland, U.S.A.

Science.gov (United States)

Soneja, Sutyajeet; Jiang, Chengsheng; Fisher, Jared; Upperman, Crystal Romeo; Mitchell, Clifford; Sapkota, Amir

2016-04-27

Several studies have investigated the association between asthma exacerbations and exposures to ambient temperature and precipitation. However, limited data exists regarding how extreme events, projected to grow in frequency, intensity, and duration in the future in response to our changing climate, will impact the risk of hospitalization for asthma. The objective of our study was to quantify the association between frequency of extreme heat and precipitation events and increased risk of hospitalization for asthma in Maryland between 2000 and 2012. We used a time-stratified case-crossover design to examine the association between exposure to extreme heat and precipitation events and risk of hospitalization for asthma (ICD-9 code 493, n = 115,923). Occurrence of extreme heat events in Maryland increased the risk of same day hospitalization for asthma (lag 0) by 3 % (Odds Ratio (OR): 1.03, 95 % Confidence Interval (CI): 1.00, 1.07), with a considerably higher risk observed for extreme heat events that occur during summer months (OR: 1.23, 95 % CI: 1.15, 1.33). Likewise, summertime extreme precipitation events increased the risk of hospitalization for asthma by 11 % in Maryland (OR: 1.11, 95 % CI: 1.06, 1.17). Across age groups, increase in risk for asthma hospitalization from exposure to extreme heat event during the summer months was most pronounced among youth and adults, while those related to extreme precipitation event was highest among ≤4 year olds. Exposure to extreme heat and extreme precipitation events, particularly during summertime, is associated with increased risk of hospitalization for asthma in Maryland. Our results suggest that projected increases in frequency of extreme heat and precipitation event will have significant impact on public health.

Demand for inputs in silkworm production: the case of Turkey

Directory of Open Access Journals (Sweden)

Osman Orkan Özer

Full Text Available ABSTRACT The objective of this study was to calculate the price, cross, and Morishima Technical Substitution elasticities for the costs of manpower, supply of mulberry leaves, transportation, heating, and material, all of which play pivotal roles for producers in sericulture. A survey was conducted by face-to-face interviews with 207 farmers within the scope of the study. At the analysis phase of the study, the share equity translog cost model was used. The response of the producers to the production input prices were calculated as inelastic. The strictest demand for an input belongs to mulberry leaves (-0.051 and the highest elasticity for transportation costs (-0.314. Sericulture dependents on workforce and mulberry leaves and this activity in Turkey is a labor-dense type of production.

Wind energy input into the upper ocean over a lengthening open water season

Science.gov (United States)

Mahoney, A. R.; Rolph, R.; Walsh, J. E.

2017-12-01

Wind energy input into the ocean has important consequences for upper ocean mixing, heat and gas exchange, and air-sea momentum transfer. In the Arctic, the open water season is increasing and extending further into the fall storm season, allowing for more wind energy input into the water column. The rate at which the delayed freeze-up timing extends into fall storm season is an important metric to evaluate because the expanding overlap between the open water period and storm season could contribute a significant amount of wind energy into the water column in a relatively short period of time. We have shown that time-integrated wind speeds over open water in the Chukchi Sea and southern Beaufort region have increased since 1979 through 2014. An integrated wind energy input value is calculated for each year in this domain over the open water season, as well as for periods over partial concentrations of ice cover. Spatial variation of this integrated wind energy is shown along the Alaskan coastline, which can have implications for different rates of coastal erosion. Spatial correlation between average wind speed over open water and open water season length from 1979-2014 show positive values in the southern Beaufort, but negative values in the northern Chukchi. This suggests possible differences in the role of the ocean on open water season length depending on region. We speculate that the warm Pacific water outflow plays a more dominant role in extending the open water season length in the northern Chukchi when compared to the southern Beaufort, and might help explain why we can show there is a relatively longer open water season length there. The negative and positive correlations in wind speeds over open water and open water season length might also be explained by oceanic changes tending to operate on longer timescales than the atmosphere. Seasonal timescales of wind events such as regional differences in overlap of the extended open water season due to regional

Radius ratio effects on natural heat transfer in concentric annulus

DEFF Research Database (Denmark)

Alipour, M.; Hosseini, R.; Kolaei, Alireza Rezania

2013-01-01

This paper studies natural convection heat transfer in vertical and electrically heated annulus. The metallic cylinders mounted concentrically in a parallel tube. Measurements are carried out for four input electric powers and three radius ratios with an apparatus immersed in stagnant air...

Niobium 1 percent zirconium/potassium and titanium/potassium life-test heat pipe design and testing

Science.gov (United States)

Sena, J. Tom; Merrigan, Michael A.

Experimental lifetime performance studies currently in progress use Niobium 1 percent Zirconium (Nb-1Zr) and Titanium (Ti) heat pipes with potassium (K) as the working fluid. A heat pipe life test matrix was developed for testing the heat pipes. Because the corrosion rates in alkali metal heat pipes are affected by temperature and working fluid evaporation flux, the variable parameters of the experimental matrix are established as steady operating temperature and input heat flux density. Total impurity inventory is a factor in corrosion rate so impurity levels are being evaluated in the heat pipe materials before and after testing. Eight Nb-1Zr/K heat pipes were designed, fabricated, and tested. Two of the heat pipes have completed testing whereas the other six are currently in test. These are gravity assist heat pipes operating in a reflux mode. The heat pipes are tested by sets, one set of two and two sets of three heat pipes. Three Ti/K heat pipes are also in life test. These heat pipes are tested as a set in a horizontal position in a capillary pumped annular flow mode. Each of the heat pipes is encapsulated in a quartz vacuum container with a water calorimeter over the vacuum container for power throughput measurements. Thermocouples are attached to the heat pipes for measuring temperature. Heat input to the heat pipes is via an RF coil. The heat pipes are operating at between 800 and 900 K, with heat input fluxes of 13.8 to 30 W/sq cm. Of the Nb-1Zr/K heat pipes, two of the heat pipes have been in operation for 14,000 hours, three over 10,000 hours, and three over 7,000 hours. The Ti/K heat pipes have been in operation for 1,266 hours.

Modelling the heat dynamics of buildings using stochastic

DEFF Research Database (Denmark)

Andersen, Klaus Kaae; Madsen, Henrik

2000-01-01

This paper describes the continuous time modelling of the heat dynamics of a building. The considered building is a residential like test house divided into two test rooms with a water based central heating. Each test room is divided into thermal zones in order to describe both short and long term...... variations. Besides modelling the heat transfer between thermal zones, attention is put on modelling the heat input from radiators and solar radiation. The applied modelling procedure is based on collected building performance data and statistical methods. The statistical methods are used in parameter...

Identification and Evaluation of Cases for Excess Heat Utilisation Using GIS

Directory of Open Access Journals (Sweden)

Fabian Bühler

2018-03-01

Full Text Available Excess heat is present in many sectors, and its utilization could reduce the primary energy use and emission of greenhouse gases. This work presents a geographical mapping of excess heat, in which excess heat from the industry and utility sector was distributed to specific geographical locations in Denmark. Based on this mapping, a systematic approach for identifying cases for the utilization of excess heat is proposed, considering the production of district heat and process heat, as well as power generation. The technical and economic feasibility of this approach was evaluated for six cases. Special focus was placed on the challenges for the connection of excess heat sources to heat users. To account for uncertainties in the model input, different methods were applied to determine the uncertainty of the results and the most important model parameters. The results show how the spatial mapping of excess heat sources can be used to identify their utilization potentials. The identified case studies show that it can be economically feasible to connect the heat sources to the public energy network or to use the heat to generate electricity. The uncertainty analysis suggests that the results are indicative and are particularly useful for a fast evaluation, comparison and prioritization of possible matches. The excess heat temperature and obtainable energy price were identified as the most important input parameters.

Measuring Dilution and Wear for Laser Cladding of Stellite 6 Produced on a P91 Steel Substrate using Two Different Heat Inputs

Directory of Open Access Journals (Sweden)

Kusmoko Alain

2016-01-01

Full Text Available Stellite 6 was deposited by laser cladding on a P91 substrate with energy inputs of 1 kW (P91-1 and 1.8 kW (P91–1.8. The chemical compositions, microstructures and surface roughnesses of these coatings were characterized by atomic absorption spectroscopy, scanning electron microscopy and atomic force microscopy. The microhardness of the coatings was measured and the wear mechanism of the coatings was evaluated using a pin-on-plate (reciprocating wear testing machine. The results showed less cracking and pore development for Stellite 6 coatings applied to the P91 steel substrate with the lower heat input (P91–1. Further, the Stellite coating for P91-1 was significantly harder than that obtained for P91–1.8. The wear test results indicated that the weight loss for P91–1 was much lower than for P91–1.8. The surface topography data indicated that the surface roughness for P91-1 was much lower than for P91–1.8. The measurements of dilution and carbon content showed that P91–1 has lower dilution and higher concentration of carbon than P91–1.8. It is concluded that the lower hardness of the coating for P91–1.8, together with the softer underlying substrate structure, markedly reduced the wear resistance of the Stellite 6 coating and the lower hardness of the coating for P91-1.8 was due to higher level of dilution and lower concentration of carbon.

Electron heating in JET by ICRH

International Nuclear Information System (INIS)

Cordey, J.G.; Christiansen, J.P.; Core, W.G.F.; Cotrell, G.A.; Eriksson, L.G.; Kovanen, M.A.; Lomas, P.; Start, D.F.H.; Taroni, A.; Tibone, F.

1991-01-01

Several ICRH experiments carried out on JET during the period 1988-90 have been directed specifically at raising the electron temperature to a high value by maximizing the total input power per particle (P tot /n). It has been found that the electron temperature saturates around 12-14 keV in sharp contrast to NBI ion heating experiments in which ion temperatures exceed 25 keV. Initial calculations suggested that this saturation was due to strongly enhanced transport in the central region. It is shown in this paper that the saturation is due to a lack of heating in the plasma center. The power input to electrons in an ICRF minority heating scheme is mainly via collisional transfer from the minority fast ions and a main problem is to maintain a peaked profile of fast ions. In the present experiments the highest fast ion energy content 4MJ has been achieved with a He 3 minority scheme, the equivalent fast ion toroidal β is 8%; electron temperatures in the range 11-14 keV are attained in these pulses. There are several possible physical effects that can give rise to the broadening of the fast ion radial profile: sawteeth, fishbones, fast ion finite orbit effects and Alfven or drift wave turbulence driven by the large gradients of fast ion pressure (discussed in section IV). The existence of such phenomena in many JET pulses means that the calculation of the power input profile by codes which contain purely classical collisional processes can be misleading. Hence an alternative approach is developed in section II; the measured fast ion energy is used directly to evaluate the power input to the central region; the scaling of the electron temperature with the actual power per particle can therefore be determined (section III). (author) 6 refs., 5 figs

Comparison between design and actual energy performance of a HVAC-ground coupled heat pump system in cooling and heating operation

Energy Technology Data Exchange (ETDEWEB)

Magraner, T.; Quilis, S. [Energesis Ingenieria S.L., Ciudad Politecnica de la Innovacion, Camino de Vera s/n, 46022 Valencia (Spain); Montero, A. [Instituto de Ingenieria Energetica, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain); Urchueguia, J.F. [Instituto Universitario de Matematica Pura y Aplicada, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)

2010-09-15

This work compares the experimental results obtained for the energy performance study of a ground coupled heat pump system with the design values predicted by means of standard methodology. The system energy performance of a monitored ground coupled heat pump system is calculated using the instantaneous measurements of temperature, flow and power consumption and these values are compared with the numerical predictions. These predictions are performed with the TRNSYS software tool following standard procedures taking the experimental thermal loads as input values. The main result of this work is that simulation results solely based on nominal heat pump capacities and performances overestimate the measured overall energy performance by a percentage between 15% and 20%. A sensitivity analysis of the simulation results to changes in percentage of its input parameters showed that the heat pump nominal coefficient of performance is the parameter that mostly affects the energy performance predictions. This analysis supports the idea that the discrepancies between experimental results and simulation outputs for this ground coupled system are mainly due to heat pump performance degradation for being used at partial load. An estimation of the impact of this effect in energy performance predictions reduces the discrepancies to values around 5%. (author)

Development of the MARS input model for Kori nuclear units 1 transient analyzer

International Nuclear Information System (INIS)

Hwang, M.; Kim, K. D.; Lee, S. W.; Lee, Y. J.; Lee, W. J.; Chung, B. D.; Jeong, J. J.

2004-11-01

KAERI has been developing the 'NSSS transient analyzer' based on best-estimate codes for Kori Nuclear Units 1 plants. The MARS and RETRAN codes have been used as the best-estimate codes for the NSSS transient analyzer. Among these codes, the MARS code is adopted for realistic analysis of small- and large-break loss-of-coolant accidents, of which break size is greater than 2 inch diameter. So it is necessary to develop the MARS input model for Kori Nuclear Units 1 plants. This report includes the input model (hydrodynamic component and heat structure models) requirements and the calculation note for the MARS input data generation for Kori Nuclear Units 1 plant analyzer (see the Appendix). In order to confirm the validity of the input data, we performed the calculations for a steady state at 100 % power operation condition and a double-ended cold leg break LOCA. The results of the steady-state calculation agree well with the design data. The results of the LOCA calculation seem to be reasonable and consistent with those of other best-estimate calculations. Therefore, the MARS input data can be used as a base input deck for the MARS transient analyzer for Kori Nuclear Units 1

High glucose increases action potential firing of catecholamine neurons in the nucleus of the solitary tract by increasing spontaneous glutamate inputs.

Science.gov (United States)

Roberts, Brandon L; Zhu, Mingyan; Zhao, Huan; Dillon, Crystal; Appleyard, Suzanne M

2017-09-01

Glucose is a crucial substrate essential for cell survival and function. Changes in glucose levels impact neuronal activity and glucose deprivation increases feeding. Several brain regions have been shown to respond to glucoprivation, including the nucleus of the solitary tract (NTS) in the brain stem. The NTS is the primary site in the brain that receives visceral afferent information from the gastrointestinal tract. The catecholaminergic (CA) subpopulation within the NTS modulates many homeostatic functions including cardiovascular reflexes, respiration, food intake, arousal, and stress. However, it is not known if they respond to changes in glucose. Here we determined whether NTS-CA neurons respond to changes in glucose concentration and the mechanism involved. We found that decreasing glucose concentrations from 5 mM to 2 mM to 1 mM, significantly decreased action potential firing in a cell-attached preparation, whereas increasing it back to 5 mM increased the firing rate. This effect was dependent on glutamate release from afferent terminals and required presynaptic 5-HT 3 Rs. Decreasing the glucose concentration also decreased both basal and 5-HT 3 R agonist-induced increase in the frequency of spontaneous glutamate inputs onto NTS-CA neurons. Low glucose also blunted 5-HT-induced inward currents in nodose ganglia neurons, which are the cell bodies of vagal afferents. The effect of low glucose in both nodose ganglia cells and in NTS slices was mimicked by the glucokinase inhibitor glucosamine. This study suggests that NTS-CA neurons are glucosensing through a presynaptic mechanism that is dependent on vagal glutamate release, 5-HT 3 R activity, and glucokinase. Copyright © 2017 the American Physiological Society.

Performance of an Advanced Stirling Convertor Based on Heat Flux Sensor Measurements

Science.gov (United States)

Wilson, Dcott D.

2012-01-01

The U.S. Department of Energy (DOE) and Lockheed Martin Space Systems Company (LMSSC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. This generator would use two highefficiency Advanced Stirling Convertors (ASCs), developed by Sunpower, Inc., and NASA Glenn Research Center. The ASCs convert thermal energy from a radioisotope heat source into electricity. As part of ground testing of these ASCs, different operating conditions are used to simulate expected mission conditions. These conditions require achieving a particular operating frequency, hot-end and cold-end temperatures, and specified electrical power output for a given heat input. It is difficult to measure heat input to Stirling convertors due to the complex geometries of the hot components, temperature limits of sensor materials, and invasive integration of sensors. A thin-film heat flux sensor was used to directly measure heat input to an ASC. The effort succeeded in designing and fabricating unique sensors, which were integrated into a Stirling convertor ground test and exposed to test temperatures exceeding 700 C in air for 10,000 hr. Sensor measurements were used to calculate thermal efficiency for ASC-E (Engineering Unit) #1 and #4. The post-disassembly condition of the sensors is also discussed.

Regeneration characteristics of desiccant rotor with microwave and hot-air heating

International Nuclear Information System (INIS)

Kubota, Mitsuhiro; Hanada, Takuya; Yabe, Satoshi; Matsuda, Hitoki

2013-01-01

Microwave heating, because of its advantages of direct and rapid heating of materials, has the potential to be employed as a novel regeneration method of desiccant rotors in humidity conditioners. We proposed a combined regeneration process, which combines microwave heating and conventional hot-air heating. The system is expected to achieve high heating rate during an initial regeneration period by assisting water desorption using the additional energy of the microwave. In this study, the regeneration characteristics of a desiccant rotor were experimentally investigated under conditions of microwave heating, hot-air heating, and combined heating at various microwave powers and hot-air temperatures. The effectiveness of the combined regeneration was evaluated in terms of the regeneration ratio, the initial regeneration rate, the temperature distribution in the rotor, and finally in terms of the energy consumption. It was demonstrated that combined heating was effective at leveling non-uniform temperature distribution in the rotor. Combined heating achieved higher ratios and initial rates in regeneration compared to just microwave and hot-air heating. This result was obviously attributed to the additional input of microwave energy, resulting that average rotor temperature increased by microwave absorption of rotor. Moreover, it was also effective for enhancement of regeneration to level the temperature distribution in the rotor by combination of two heating methods with different heating mechanisms. Both the initial regeneration rate and the equilibrium regeneration ratio for combined heating were found to increase as the microwave power increased. A linear relationship was observed with respect to microwave power. From the viewpoint of energy consumption, it may be possible to apply combined and microwave heating to humidity control systems that switch between adsorption and regeneration in short cycle times, if the conversion and absorption efficiencies of the

Power absorption and confinement studies of ICRF-heated plasma in JIPP T-IIU tokamak

International Nuclear Information System (INIS)

Ida, K.; Ogawa, Y.; Toi, K.

1988-08-01

The energy confinement characteristics of ICRF-heated tokamak plasmas are studied at high input power density ∼ 2 MWm -3 volume averaged, on the JIPP T-IIU device(R = 0.91 m/a = 0.23 m). High electron and ion temperatures (T e ∼ 2.5 keV, T i ∼ 2.0 keV, at each maximum) have been achieved by the operation at a plasma current I P of 280 kA, plasma line-averaged electron density n-bar e of 7 x 10 13 cm -3 and input power of 2 MW, with a suppression of total radiation loss (30 to 40 % of the total input power) by a carbon coating on the vacuum vessel. The fraction of ICRF power absorbed by the plasma, α, is determined experimentally from the decay of the stored plasma energy just after the ICRF pulse is terminated. The value of α increases slightly with increasing electron density and decreases from 90 to 70 % as the ICRF power is increased from 1 MWm -3 to 2 MWm -3 volume averaged. The global energy confinement time τ E , defined by W P /(P OH + αP rf ), decreases by a factor of 2 ∼ 3 from that in ohmic plasmas as the heating power increases up to 2 MW. It is found that the energy confinement time has a strong line-averaged electron density dependence as τ E ∝n-bar e 0.6 , which is obtained by the use of the measured absorbed power, while the Kaye-Goldston scaling predicts τ E ∝n-bar e 0.26 . (author)

Energy Input Flux in the Global Quiet-Sun Corona

Energy Technology Data Exchange (ETDEWEB)

Mac Cormack, Cecilia; Vásquez, Alberto M.; López Fuentes, Marcelo; Nuevo, Federico A. [Instituto de Astronomía y Física del Espacio (IAFE), CONICET-UBA, CC 67—Suc 28, (C1428ZAA) Ciudad Autónoma de Buenos Aires (Argentina); Landi, Enrico; Frazin, Richard A. [Department of Climate and Space Sciences and Engineering (CLaSP), University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109-2143 (United States)

2017-07-01

We present first results of a novel technique that provides, for the first time, constraints on the energy input flux at the coronal base ( r ∼ 1.025 R {sub ⊙}) of the quiet Sun at a global scale. By combining differential emission measure tomography of EUV images, with global models of the coronal magnetic field, we estimate the energy input flux at the coronal base that is required to maintain thermodynamically stable structures. The technique is described in detail and first applied to data provided by the Extreme Ultraviolet Imager instrument, on board the Solar TErrestrial RElations Observatory mission, and the Atmospheric Imaging Assembly instrument, on board the Solar Dynamics Observatory mission, for two solar rotations with different levels of activity. Our analysis indicates that the typical energy input flux at the coronal base of magnetic loops in the quiet Sun is in the range ∼0.5–2.0 × 10{sup 5} (erg s{sup −1} cm{sup −2}), depending on the structure size and level of activity. A large fraction of this energy input, or even its totality, could be accounted for by Alfvén waves, as shown by recent independent observational estimates derived from determinations of the non-thermal broadening of spectral lines in the coronal base of quiet-Sun regions. This new tomography product will be useful for the validation of coronal heating models in magnetohydrodinamic simulations of the global corona.

Air pollution prevention through urban heat island mitigation: An update on the urban heat island pilot project

Energy Technology Data Exchange (ETDEWEB)

Gorsevski, V.; Taha, H.; Quattrochi, D.; Luvall, J.

1998-07-01

Urban heat islands increase the demand for cooling energy and accelerate the formation of smog. They are created when natural vegetation is replaced by heat-absorbing surfaces such as building roofs and walls, parking lots, and streets. Through the implementation of measures designed to mitigate the urban heat island, communities can decrease their demand for energy and effectively cool the metropolitan landscape. In addition to the economic benefits, using less energy leads to reductions in emission of CO{sub 2}--a greenhouse gas--as well as ozone (smog) precursors such as NOx and VOCs. Because ozone is created when NOx and VOCs photochemically combine with heat and solar radiation, actions taken to lower ambient air temperature can significantly reduce ozone concentrations in certain areas. Measures to reverse the urban heat island include afforestation and the widespread use of highly reflective surfaces. To demonstrate the potential benefits of implementing these measures, EPA has teamed up with NASA and LBNL to initiate a pilot project with three US cities. As part of the pilot, NASA will use remotely-sensed data to quantify surface temperature, albedo, the thermal response number and NDVI vegetation of each city. This information will be used by scientists at Lawrence Berkeley National Laboratory (LBNL) along with other data as inputs to model various scenarios that will help quantify the potential benefits of urban heat island mitigation measures in terms of reduced energy use and pollution. This paper will briefly describe this pilot project and provide an update on the progress to date.

Soil heat flux and day time surface energy balance closure at ...

Indian Academy of Sciences (India)

Soil heat flux is an important input component of surface energy balance. Estimates of soil heat flux were ... mate source of energy for all physical and bio- logical processes ... May) account for major thunderstorm activity in the state and winter ...

Design of the RF system for Alfven wave heating and current drive in a TCA/BR tokamak

International Nuclear Information System (INIS)

Ruchko, L.; Andrade, M.L.; Ozono, E.; Galvao, R.M.O.; Degaspari, F.T.; Nascimento, I.C.

1995-01-01

The advanced RF system for Alfven wave plasma heating and current drive in TCA/BR tokamak is presented. The antenna system is capable of exciting the standing and travelling wave M = -1,N = 1,N =-4,-6 with single helicity and thus provides the possibility to improve Alfven wave plasma heating efficiency in TCA/BR tokamak and to increase input power level up to P ≅ 1 MW, without the uncontrolled density rise which was encountered in previous TCA (Switzerland) experiments. (author). 4 refs., 3 figs

Analysis of input variables of an artificial neural network using bivariate correlation and canonical correlation

Energy Technology Data Exchange (ETDEWEB)

Costa, Valter Magalhaes; Pereira, Iraci Martinez, E-mail: valter.costa@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

The monitoring of variables and diagnosis of sensor fault in nuclear power plants or processes industries is very important because a previous diagnosis allows the correction of the fault and, like this, to prevent the production stopped, improving operator's security and it's not provoking economics losses. The objective of this work is to build a set, using bivariate correlation and canonical correlation, which will be the set of input variables of an artificial neural network to monitor the greater number of variables. This methodology was applied to the IEA-R1 Research Reactor at IPEN. Initially, for the input set of neural network we selected the variables: nuclear power, primary circuit flow rate, control/safety rod position and difference in pressure in the core of the reactor, because almost whole of monitoring variables have relation with the variables early described or its effect can be result of the interaction of two or more. The nuclear power is related to the increasing and decreasing of temperatures as well as the amount radiation due fission of the uranium; the rods are controls of power and influence in the amount of radiation and increasing and decreasing of temperatures; the primary circuit flow rate has the function of energy transport by removing the nucleus heat. An artificial neural network was trained and the results were satisfactory since the IEA-R1 Data Acquisition System reactor monitors 64 variables and, with a set of 9 input variables resulting from the correlation analysis, it was possible to monitor 51 variables. (author)

Analysis of input variables of an artificial neural network using bivariate correlation and canonical correlation

International Nuclear Information System (INIS)

Costa, Valter Magalhaes; Pereira, Iraci Martinez

2011-01-01

The monitoring of variables and diagnosis of sensor fault in nuclear power plants or processes industries is very important because a previous diagnosis allows the correction of the fault and, like this, to prevent the production stopped, improving operator's security and it's not provoking economics losses. The objective of this work is to build a set, using bivariate correlation and canonical correlation, which will be the set of input variables of an artificial neural network to monitor the greater number of variables. This methodology was applied to the IEA-R1 Research Reactor at IPEN. Initially, for the input set of neural network we selected the variables: nuclear power, primary circuit flow rate, control/safety rod position and difference in pressure in the core of the reactor, because almost whole of monitoring variables have relation with the variables early described or its effect can be result of the interaction of two or more. The nuclear power is related to the increasing and decreasing of temperatures as well as the amount radiation due fission of the uranium; the rods are controls of power and influence in the amount of radiation and increasing and decreasing of temperatures; the primary circuit flow rate has the function of energy transport by removing the nucleus heat. An artificial neural network was trained and the results were satisfactory since the IEA-R1 Data Acquisition System reactor monitors 64 variables and, with a set of 9 input variables resulting from the correlation analysis, it was possible to monitor 51 variables. (author)

The role of hybrid nanofluids in improving the thermal characteristics of screen mesh cylindrical heat pipes

Directory of Open Access Journals (Sweden)

Ramachandran Raghavan Nair

2016-01-01

Full Text Available Experiments were conducted to study the thermal performance of meshed wick heat pipe by varying the working fluid and heat input. In this work four screen mesh wicked heat pipes were fabricated and tested. All the heat pipes were tested for heat input from 50W to 250W each with an increment of 50W in each step. The heat input range selected in this study is commonly encountered in most of the electronic application devices. The thermal resistance of all the heat pipes charged with different working fluids such as DI water, Al2O3/DI water nanofluid of volume concentration 0.1 % and hybrid nanofluid volume concentration 0.1%( with two different combinations of (Al2O3 50%- CuO 50%/DI water and (Al2O3 25%- CuO 75%/DI waterwas determined. The maximum percentage reduction was found to be 58.87% for the hybrid nanofluid of (Al2O3 25%- CuO 75%/DI water compared to base fluid. An important observation from the study is that, use of hybrid nanofluid can raise the operating range of the heat pipe beyond 250W which makes hybrid nanofluid as a potential substitute for the conventional working fluid.

Heat-pipe transient model for space applications

International Nuclear Information System (INIS)

Tournier, J.; El-Genk, M.S.; Juhasz, A.J.

1991-01-01

A two-dimensional model is developed for simulating heat pipes transient performance following changes in the input/rejection power or in the evaporator/condenser temperatures. The model employs the complete form of governing equations and momentum and energy jump conditions at the liquid-vapor interface. Although the model is capable of handling both cylindrical and rectangular geometries, the results reported are for a circular heat pipe with liquid lithium as the working fluid. The model incorporates a variety of other working fluids, such as water, ammonia, potassium, sodium, and mercury, and offers combinations of isothermal, isoflux, convective and radiative heating/cooling conditions in the evaporator and condenser regions of the heat pipe. Results presented are for lithium heat pipes with exponential heating of the evaporator and isothermal cooling of the condenser

Increased efficiency of targeted mutagenesis by CRISPR/Cas9 in plants using heat stress.

Science.gov (United States)

LeBlanc, Chantal; Zhang, Fei; Mendez, Josefina; Lozano, Yamile; Chatpar, Krishna; Irish, Vivian F; Jacob, Yannick

2018-01-01

The CRISPR/Cas9 system has greatly improved our ability to engineer targeted mutations in eukaryotic genomes. While CRISPR/Cas9 appears to work universally, the efficiency of targeted mutagenesis and the adverse generation of off-target mutations vary greatly between different organisms. In this study, we report that Arabidopsis plants subjected to heat stress at 37°C show much higher frequencies of CRISPR-induced mutations compared to plants grown continuously at the standard temperature (22°C). Using quantitative assays relying on green fluorescent protein (GFP) reporter genes, we found that targeted mutagenesis by CRISPR/Cas9 in Arabidopsis is increased by approximately 5-fold in somatic tissues and up to 100-fold in the germline upon heat treatment. This effect of temperature on the mutation rate is not limited to Arabidopsis, as we observed a similar increase in targeted mutations by CRISPR/Cas9 in Citrus plants exposed to heat stress at 37°C. In vitro assays demonstrate that Cas9 from Streptococcus pyogenes (SpCas9) is more active in creating double-stranded DNA breaks at 37°C than at 22°C, thus indicating a potential contributing mechanism for the in vivo effect of temperature on CRISPR/Cas9. This study reveals the importance of temperature in modulating SpCas9 activity in eukaryotes, and provides a simple method to increase on-target mutagenesis in plants using CRISPR/Cas9. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

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...... 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...... 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...

Tracing the recently increasing anthropogenic Pb inputs into the East China Sea shelf sediments using Pb isotopic analysis

International Nuclear Information System (INIS)

Wang, Deli; Zhao, Zhiqi; Dai, Minhan

2014-01-01

Highlights: • Lithogenic Pb dominated in the ECS shelf sediments. • Small but increasing anthropogenic Pb occurred in the ECS shelf sediments. • HCl-leachated Pb suggested a source from “polluted” coastal sediments. • Residual Pb was mainly contributed from the “pristine” upper Yangtze watershed. - Abstract: This study examined the Pb content and Pb isotopic composition in a sediment core taken from the East China Sea (ECS) shelf, and it was observed that since 2003 the increasing anthropogenic Pb inputs have impacted as far as the ECS shelf sediments. The ECS shelf sediments were generally characterized with low bulk Pb contents (12.5–15.0 μg/g) and relatively lithogenic Pb isotopic signatures (both HCl-leached and residual fractions). However, elevated Pb records along with lighter Pb isotopic signals have occurred in the post-2003 sediments, as a result of a small but increasing anthropogenic Pb contribution from the heavily human perturbed coastal sediments due to the sharply increasing coal consumption in mainland China since 2003

Heat transfer and structure stress analysis of micro packaging component of high power light emitting diode

Directory of Open Access Journals (Sweden)

Hsu Chih-Neng

2013-01-01

Full Text Available This paper focuses on the heat transfer and structural stress analysis of the micro- scale packaging structure of a high-power light emitting diode. The thermal-effect and thermal-stress of light emitting diode are determined numerically. Light emitting diode is attached to the silicon substrate through the wire bonding process by using epoxy as die bond material. The silicon substrate is etched with holes at the bottom and filled with high conductivity copper material. The chip temperature and structure stress increase with input power consumption. The micro light emitting diode is mounted on the heat sink to increase the heat dissipation performance, to decrease chip temperature, to enhance the material structure reliability and safety, and to avoid structure failure as well. This paper has successfully used the finite element method to the micro-scale light emitting diode heat transfer and stress concentration at the edges through etched holes.

Efficient round-robin multicast scheduling for input-queued switches

DEFF Research Database (Denmark)

Rasmussen, Anders; Yu, Hao; Ruepp, Sarah Renée

2014-01-01

The input-queued (IQ) switch architecture is favoured for designing multicast high-speed switches because of its scalability and low implementation complexity. However, using the first-in-first-out (FIFO) queueing discipline at each input of the switch may cause the head-of-line (HOL) blocking...... problem. Using a separate queue for each output port at an input to reduce the HOL blocking, that is, the virtual output queuing discipline, increases the implementation complexity, which limits the scalability. Given the increasing link speed and network capacity, a low-complexity yet efficient multicast...... by means of queue look-ahead. Simulation results demonstrate that this FIFO-based IQ multicast architecture is able to achieve significant improvements in terms of multicast latency requirements by searching through a small number of cells beyond the HOL cells in the input queues. Furthermore, hardware...

30-year changes in the nitrogen inputs to the Yangtze River Basin

International Nuclear Information System (INIS)

Wang, Qinxue; Koshikawa, Hiroshi; Liu, Chen; Otsubo, Kuninori

2014-01-01

To understand both spatial and temporal changes in nitrogen inputs to the Yangtze River Basin (YRB), we collected decadal statistical data for 1980, 1990, 2000 and 2010 at the county level and the annual statistical data for the period 1980–2010 at the provincial level of China. Based on these datasets, we estimated the nitrogen inputs, including the atmospheric deposition, synthetic N fertilizer, biological N fixation and recycling reactive N inputs, such as N from human waste and animal excrement, crop residue recycled as manure, and N emission from burning crop residue. The results showed that, geographically, the variation of the total amount of N input during the last 30 years (δN = N 2010  – N 1980 ) has increased about 0–50 kg ha −1 over most of the area of the YRB. Moreover, it has increased dramatically by about 50–300 kg ha −1 in the Sichuan Basin, the Han River Basin, the Poyang and Dongting lake basins, and the Yangtze Delta as well. Temporally, the total amount of N inputs to the whole YRB was approximately 16.4 Tg N in 2010, which was a 2.0-fold increase over 1980. It increased dramatically in the 1990s and then stabilized at a high level in the 2000s. The major N inputs were human and animal wastes as well as synthetic fertilizers, but they varied regionally. Animal waste was the major input to the water source regions, and its contribution percentage gradually decreased from upper to lower reaches. In contrast, the contribution of N fertilizer increased from upper to lower reaches, and became the major input to the middle and lower reaches. The total N inputs changed slightly in the upper reaches, but increased largely in the middle reaches in the last 30 years. However, in the lower reaches, it had increased remarkably before 2000, and then tended to decrease in the last decade. Finally, the atmospheric N deposition over the basin increased continuously in the last 30 years. (paper)

A thermal sensor for water using self-heated NTC thick-film segmented thermistors

OpenAIRE

Nikolić, Maria Vesna; Radojčić, B. M.; Aleksić, Obrad; Luković, Miloljub D.; Nikolić, Pantelija

2011-01-01

A simple thermal (heat loss) sensor system was designed in a small plastic tube housing using a negative thermal coefficient (NTC) thick-film thermistor as a self-heating sensor. The voltage power supply [range constant voltage (RCV)-range constant voltage] uses the measured input water temperature to select the applied voltage in steps (up and down) in order to enable operation of the sensor at optimal sensitivity for different water temperatures. The input water temperature was measured usi...

Non-lethal heat shock increased Hsp70 and immune protein transcripts but not Vibrio tolerance in the white-leg shrimp.

Directory of Open Access Journals (Sweden)

Nguyen Hong Loc

Full Text Available Non-lethal heat shock boosts bacterial and viral disease tolerance in shrimp, possibly due to increases in endogenous heat shock protein 70 (Hsp70 and/or immune proteins. To further understand the mechanisms protecting shrimp against infection, Hsp70 and the mRNAs encoding the immune-related proteins prophenoloxidase (proPO, peroxinectin, penaeidin, crustin and hemocyanin were studied in post-larvae of the white-leg shrimp Litopenaeus vannamei, following a non-lethal heat shock. As indicated by RT-qPCR, a 30 min abrupt heat shock increased Hsp70 mRNA in comparison to non-heated animals. Immunoprobing of western blots and quantification by ELISA revealed that Hsp70 production after heat shock was correlated with enhanced Hsp70 mRNA. proPO and hemocyanin mRNA levels were augmented, whereas peroxinectin and crustin mRNA levels were unchanged following non-lethal heat shock. Penaeidin mRNA was decreased by all heat shock treatments. Thirty min abrupt heat shock failed to improve survival of post-larvae in a standardized challenge test with Vibrio harveyi, indicating that under the conditions of this study, L. vannamei tolerance to Vibrio infection was influenced neither by Hsp70 accumulation nor the changes in the immune-related proteins, observations dissimilar to other shrimp species examined.

Non-Lethal Heat Shock Increased Hsp70 and Immune Protein Transcripts but Not Vibrio Tolerance in the White-Leg Shrimp

Science.gov (United States)

Loc, Nguyen Hong; MacRae, Thomas H.; Musa, Najiah; Bin Abdullah, Muhd Danish Daniel; Abdul Wahid, Mohd. Effendy; Sung, Yeong Yik

2013-01-01

Non-lethal heat shock boosts bacterial and viral disease tolerance in shrimp, possibly due to increases in endogenous heat shock protein 70 (Hsp70) and/or immune proteins. To further understand the mechanisms protecting shrimp against infection, Hsp70 and the mRNAs encoding the immune-related proteins prophenoloxidase (proPO), peroxinectin, penaeidin, crustin and hemocyanin were studied in post-larvae of the white-leg shrimp Litopenaeus vannamei, following a non-lethal heat shock. As indicated by RT-qPCR, a 30 min abrupt heat shock increased Hsp70 mRNA in comparison to non-heated animals. Immunoprobing of western blots and quantification by ELISA revealed that Hsp70 production after heat shock was correlated with enhanced Hsp70 mRNA. proPO and hemocyanin mRNA levels were augmented, whereas peroxinectin and crustin mRNA levels were unchanged following non-lethal heat shock. Penaeidin mRNA was decreased by all heat shock treatments. Thirty min abrupt heat shock failed to improve survival of post-larvae in a standardized challenge test with Vibrio harveyi, indicating that under the conditions of this study, L. vannamei tolerance to Vibrio infection was influenced neither by Hsp70 accumulation nor the changes in the immune-related proteins, observations dissimilar to other shrimp species examined. PMID:24039886

Probabilistic tectonic heat flow modelling for basin maturation: method and applications

NARCIS (Netherlands)

van Wees, J.D.A.M.; van Bergen, F.; David, P.; Nepveu, M.; Beekman, W.W.W.; Cloetingh, S.A.P.L.; Bonte, D.D.P.

2009-01-01

Tectonic modeling is often neglected in the basin modeling workflow and heat flow is most times considered a user input. Such heat flows can, therefore, result in erroneous basin modeling outcomes, resulting in false overoptimistic identification of prospective areas or failure to identify

Increased certification of semi-device independent random numbers using many inputs and more post-processing

International Nuclear Information System (INIS)

Mironowicz, Piotr; Tavakoli, Armin; Hameedi, Alley; Marques, Breno; Bourennane, Mohamed; Pawłowski, Marcin

2016-01-01

Quantum communication with systems of dimension larger than two provides advantages in information processing tasks. Examples include higher rates of key distribution and random number generation. The main disadvantage of using such multi-dimensional quantum systems is the increased complexity of the experimental setup. Here, we analyze a not-so-obvious problem: the relation between randomness certification and computational requirements of the post-processing of experimental data. In particular, we consider semi-device independent randomness certification from an experiment using a four dimensional quantum system to violate the classical bound of a random access code. Using state-of-the-art techniques, a smaller quantum violation requires more computational power to demonstrate randomness, which at some point becomes impossible with today’s computers although the randomness is (probably) still there. We show that by dedicating more input settings of the experiment to randomness certification, then by more computational postprocessing of the experimental data which corresponds to a quantum violation, one may increase the amount of certified randomness. Furthermore, we introduce a method that significantly lowers the computational complexity of randomness certification. Our results show how more randomness can be generated without altering the hardware and indicate a path for future semi-device independent protocols to follow. (paper)

Experimental and Numerical Investigation of Forced Convection Heat Transfer in Heat Sink with Rectangular Plates at Varying Inclinations on Vertical Base

Science.gov (United States)

Patil, Harshal Bhauso; Dingare, Sunil Vishnu

2018-03-01

Heat exchange upgrade is a vital territory of research area. Utilization of reasonable systems can bring about noteworthy specialized points of interest coming about reserve funds of cost. Rectangular plates are viewed as best balance arrangement utilized for heat exchange improvement. This gives an enlargement strategy to heat exchange with beginning of limit layer and vortex development. To assess and look at the rate of heat exchange enhancement by rectangular plate fins with differing inclinations (0°-30°-60°), shifting Re and heat supply under forced convection are the principle destinations of this study. The study is done by fluctuating introductions of fins with various inclinations, input heat supply and Re under forced convection. The coefficient of heat transfer increments observed with the expansion in air speed for all the examined designs. The coefficient of the heat transfer is discovered higher at the edge of introduction of fins at 30° for inline arrangement and 0° for staggered arrangement. Looking at both the arrangements, it is discovered that the heat transfer coefficient in 0° fin staggered arrangement is about 17% higher than 30° inline arrangement and 76% higher than the vertical plate fin. For plate fin heat sink, boundary layer formation and growth results in decrease of the coefficient of heat transfer in forced convection. This issue is overcome by accommodating some rectangular fins on the plate fin. It brings about increment of heat transfer coefficient of the RPFHS under the states of trial factors. As indicated by past research, it is discovered that examination of the plate fin heat sink with various sorts of fins for horizontal orientation is done yet but this investigation expects to discover the upgrade of transfer coefficient of plate fin heat sink for its vertical position with rectangular plates at different inclinations under the shifting scopes of heat input supply, fin arrangements and Reynolds number (Re).

Solar Load Inputs for USARIEM Thermal Strain Models and the Solar Radiation-Sensitive Components of the WBGT Index

National Research Council Canada - National Science Library

Matthew, William

2001-01-01

This report describes processes we have implemented to use global pyranometer-based estimates of mean radiant temperature as the common solar load input for the Scenario model, the USARIEM heat strain...

Increased heat fluxes near a forest edge

NARCIS (Netherlands)

Klaassen, W; van Breugel, PB; Moors, EJ; Nieveen, JP

2002-01-01

Observations of sensible and latent heat flux above forest downwind of a forest edge show these fluxes to be larger than the available energy over the forest. The enhancement averages to 56 W m(-2), or 16% of the net radiation, at fetches less than 400 m, equivalent to fetch to height ratios less

Increased heat fluxes near a forest edge

NARCIS (Netherlands)

Klaassen, W.; Breugel, van P.B.; Moors, E.J.; Nieveen, J.P.

2002-01-01

Observations of sensible and latent heat flux above forest downwind of a forest edge show these fluxes to be larger than the available energy over the forest. The enhancement averages to 56 W mm2, or 16 f the net radiation, at fetches less than 400 m, equivalent to fetch to height ratios less than

Feed and manure use in low-N-input and high-N-input dairy cattle production systems

Science.gov (United States)

Powell, J. Mark

2014-11-01

In most parts of Sub-Saharan Africa fertilizers and feeds are costly, not readily available and used sparingly in agricultural production. In many parts of Western Europe, North America, and Oceania fertilizers and feeds are relatively inexpensive, readily available and used abundantly to maximize profitable agricultural production. A case study, dairy systems approach was used to illustrate how differences in feed and manure management in a low-N-input dairy cattle system (Niger, West Africa) and a high-N-input dairy production system (Wisconsin, USA) impact agricultural production and environmental N loss. In Niger, an additional daily feed N intake of 114 g per dairy animal unit (AU, 1000 kg live weight) could increase annual milk production from 560 to 1320 kg AU-1, and the additional manure N could greatly increase millet production. In Wisconsin, reductions in daily feed N intake of 100 g AU-1 would not greatly impact milk production but decrease urinary N excretion by 25% and ammonia and nitrous oxide emissions from manure by 18% to 30%. In Niger, compared to the practice of housing livestock and applying dung only onto fields, corralling cattle or sheep on cropland (to capture urinary N) increased millet yields by 25% to 95%. The additional millet grain due to dung applications or corralling would satisfy the annual food grain requirements of 2-5 persons; the additional forage would provide 120-300 more days of feed for a typical head of cattle; and 850 to 1600 kg ha-1 more biomass would be available for soil conservation. In Wisconsin, compared to application of barn manure only, corralling heifers in fields increased forage production by only 8% to 11%. The application of barn manure or corralling increased forage production by 20% to 70%. This additional forage would provide 350-580 more days of feed for a typical dairy heifer. Study results demonstrate how different approaches to feed and manure management in low-N-input and high-N-input dairy cattle

Miniature Heat Transport System for Spacecraft Thermal Control

Science.gov (United States)

Ochterbeck, Jay M.; Ku, Jentung (Technical Monitor)

2002-01-01

Loop heat pipes (LHP) are efficient devices for heat transfer and use the basic principle of a closed evaporation-condensation cycle. The advantage of using a loop heat pipe over other conventional methods is that large quantities of heat can be transported through a small cross-sectional area over a considerable distance with no additional power input to the system. By using LHPs, it seems possible to meet the growing demand for high-power cooling devices. Although they are somewhat similar to conventional heat pipes, LHPs have a whole set of unique properties, such as low pressure drops and flexible lines between condenser and evaporator, that make them rather promising. LHPs are capable of providing a means of transporting heat over long distances with no input power other than the heat being transported because of the specially designed evaporator and the separation of liquid and vapor lines. For LHP design and fabrication, preliminary analysis on the basis of dimensionless criteria is necessary because of certain complicated phenomena that take place in the heat pipe. Modeling the performance of the LHP and miniaturizing its size are tasks and objectives of current research. In the course of h s work, the LHP and its components, including the evaporator (the most critical and complex part of the LHP), were modeled with the corresponding dimensionless groups also being investigated. Next, analysis of heat and mass transfer processes in the LHP, selection of the most weighted criteria from known dimensionless groups (thermal-fluid sciences), heat transfer rate limits, (heat pipe theory), and experimental ratios which are unique to a given heat pipe class are discussed. In the third part of the report, two-phase flow heat and mass transfer performances inside the LHP condenser are analyzed and calculated for Earth-normal gravity and microgravity conditions. On the basis of recent models and experimental databanks, an analysis for condensing two-phase flow regimes

Corrosion protected reversing heat exchanger

International Nuclear Information System (INIS)

Zawierucha, R.

1984-01-01

A reversing heat exchanger of the plate and fin type having multiple aluminum parting sheets in a stacked arrangement with corrugated fins separating the sheets to form multiple flow paths, means for closing the ends of the sheets, an input manifold arrangement of headers for the warm end of of the exchanger and an output manifold arrangement for the cold end of the exchanger with the input air feed stream header and the waste gas exhaust header having an alloy of zinc and aluminum coated on the inside surface for providing corrosion protection to the stack

Self-optimizing control of air-source heat pump with multivariable extremum seeking

International Nuclear Information System (INIS)

Dong, Liujia; Li, Yaoyu; Mu, Baojie; Xiao, Yan

2015-01-01

The air-source heat pump (ASHP) is widely adopted for cooling and heating of residential and commercial buildings. The performance of ASHP can be controlled by several operating variables, such as compressor capacity, condenser fan speed, evaporator fan speed and suction superheat. In practice, the system characteristics can be varied significantly by the variations in ambient condition, operation setpoint, internal thermal load and equipment degradation, which makes it difficult to obtain accurate plant models. As consequence, the model based control strategies for ASHP could limit the achievable energy efficiency. Model-free self-optimizing control strategies are thus more preferable. In this study, a multi-input extremum seeking control (ESC) scheme is proposed for both heating and cooling operation of ASHP. The zone temperature is assumed to be regulated by the compressor capacity, while the expansion valve opening is used to regulate the suction superheat at the given setpoint. The total power consumption of the compressor, the condenser fan and the evaporator fan is measured as input to the ESC, while the ESC controls the evaporator fan speed, the condenser fan speed and the suction superheat setpoint. The proposed scheme is evaluated with a Modelica based dynamic simulation model of ASHP under both cooling and heating modes of operation. Simulation results show the effectiveness of the proposed scheme to achieve the maximum achievable efficiency in a nearly model-free manner. - Highlights: • Multi-input ESC. • Air-source heat pump. • Cooling and heating. • Modelica based model

Learning Complex Grammar in the Virtual Classroom: A Comparison of Processing Instruction, Structured Input, Computerized Visual Input Enhancement, and Traditional Instruction

Science.gov (United States)

Russell, Victoria

2012-01-01

This study investigated the effects of processing instruction (PI) and structured input (SI) on the acquisition of the subjunctive in adjectival clauses by 92 second-semester distance learners of Spanish. Computerized visual input enhancement (VIE) was combined with PI and SI in an attempt to increase the salience of the targeted grammatical form…

Increase in Export Production in the Marginal Seas of the Northwestern Pacific in Response to Anthropogenic N Input

Science.gov (United States)

Lee, K.; Ko, Y. H.; Moon, J. Y.

2017-12-01

The relative abundance of nitrate (N) over phosphorus (P) has increased significantly over the period since 1980 in the marginal seas (Yellow, East China and East seas) bordering the northwestern Pacific Ocean, located downstream of the populated and industrialized Asian continent. Analysis of datasets for anthropogenic N input, satellite chlorophyll-a (Chl-a), and seawater nutrient data ( 200,000 data points) reveal that transport of N originating from China has been responsible for enhancements of Chl-a in the marginal seas of the northwestern Pacific Ocean. In particular, the contribution of anthropogenic N to new production in these marginal seas is expected to grow considerably in the coming decades. This anthropogenically driven increase in the N content may potentially lead to a long-term change of these marginal seas from being N-limited to P-limited.

TART input manual

International Nuclear Information System (INIS)

Kimlinger, J.R.; Plechaty, E.F.

1982-01-01

The TART code is a Monte Carlo neutron/photon transport code that is only on the CRAY computer. All the input cards for the TART code are listed, and definitions for all input parameters are given. The execution and limitations of the code are described, and input for two sample problems are given

Heat transfer correlations in mantle tanks

DEFF Research Database (Denmark)

Furbo, Simon; Knudsen, Søren

2005-01-01

on calculations with a CFD-model, which has earlier been validated by means of experiments. The CFD-model is used to determine the heat transfer between the solar collector fluid in the mantle and the walls surrounding the mantle in all levels of the mantle as well as the heat transfer between the wall...... transfer correlations are suitable as input for a detailed simulation model for mantle tanks. The heat transfer correlations determined in this study are somewhat different from previous reported heat transfer correlations. The reason is that this study includes more mantle tank designs and operation......Small solar domestic hot water systems are best designed as low flow systems based on vertical mantle tanks. Theoretical investigations of the heat transfer in differently designed vertical mantle tanks during different operation conditions have been carried out. The investigations are based...

Accounting and analysis of the real labour input for objects and types of works during NPP construction

International Nuclear Information System (INIS)

Shuvaev, P.P.

1983-01-01

A technique for determining the actual labour input for PP construction according to types of works, construction units and objects is considered. The data are presented on specific expenditures on civil engineering, heat and electric installation, insulation and anticorrosion works for construction of the Chernobylsk and Kursk NPPs. A conclusion is drawn about the necessity of computer utilization in calculating the labour input for different types of works, number of workers and planning works during the NPP construction

Prediction of heat generation in rubber or rubber-metal springs

Directory of Open Access Journals (Sweden)

Banić Milan S.

2012-01-01

Full Text Available The temperature of rubber or rubber-metal springs increases under cyclic loading, due to hysteresis losses and low rubber thermal conductivity. Hysteresis losses correspond to energy dissipation from the rubber, which is primarily converted into heat. This well-known phenomenon, called heat build-up, is the primary reason for rubber aging. Increase in temperature within the rubber compound leads to degradation of its physical and chemical properties, increase in stiffness and loss of damping capability. This paper presents a novel procedure of heat generation prediction in rubber or rubber-metal springs. The procedure encompasses the prediction of hysteresis loss, i. e. dissipated energy within the rubber, by finite element analysis and application of a modern visco-plastic rubber constitutive model. The obtained dissipated energy was used as an input for transient thermal analysis. Verification of the proposed procedure was performed by comparison of simulation results with experimentally obtained data during the dynamic loading of the rubber specimen. The proposed procedure is highly computationally efficient and it enables time integration, which can be problematic in coupled mechanical thermal analysis. [Projekat Ministarstva nauke Republike Srbije, br. TR35005: Research and Development of New Generation of Wind Turbines of High Energy Efficiency

Modelling and performance of heat pipes with long evaporator sections

Science.gov (United States)

Wits, Wessel W.; te Riele, Gert Jan

2017-11-01

This paper presents a planar cooling strategy for advanced electronic applications using heat pipe technology. The principle idea is to use an array of relatively long heat pipes, whereby heat is disposed to a long section of the pipes. The proposed design uses 1 m long heat pipes and top cooling through a fan-based heat sink. Successful heat pipe operation and experimental performances are determined for seven heating configurations, considering active bottom, middle and top sections, and four orientation angles (0°, 30°, 60° and 90°). For all heating sections active, the heat pipe oriented vertically in an evaporator-down mode and a power input of 150 W, the overall thermal resistance was 0.014 K/W at a thermal gradient of 2.1 K and an average operating temperature of 50.7 °C. Vertical operation showed best results, as can be expected; horizontally the heat pipe could not be tested up to the power limit and dry-out occurred between 20 and 80 W depending on the heating configuration. Heating configurations without the bottom section active demonstrated a dynamic start-up effect, caused by heat conduction towards the liquid pool and thereafter batch-wise introducing the working fluid into the two-phase cycle. By analysing the heat pipe limitations for the intended operating conditions, a suitable heat pipe geometry was chosen. To predict the thermal performance a thermal model using a resistance network was created. The model compares well with the measurement data, especially for higher input powers. Finally, the thermal model is used for the design of a 1 kW planar system-level electronics cooling infrastructure featuring six 1 m heat pipes in parallel having a long ( 75%) evaporator section.

Energy efficiency of electrical infrared heating elements

International Nuclear Information System (INIS)

Brown, K.J.; Farrelly, R.; O’Shaughnessy, S.M.; Robinson, A.J.

2016-01-01

Highlights: • Characterization of the radiant energy efficiency of infrared heating elements. • Performed for a commercially available ceramic heater element for two cases. • Total radiant power and net radiant efficiency is computed. • Radiant efficiencies are strongly dependant on the input power to the element. • In-plane efficiencies depend on the distance from the heater. - Abstract: A measurement system has been designed to characterize the radiant energy efficiency of infrared heating elements. The system also allows for measurement of the radiant heat flux distribution emitted from radiant heater assemblies. To facilitate these, a 6-axis robotic arm is fitted with a Schmidt–Boelter radiant heat flux gauge. A LabVIEW interface operates the robot and positions the sensor in the desired location and subsequently acquires the desired radiant heat flux measurement. To illustrate the functionality of the measurement system and methodology, radiant heat flux distributions and efficiency calculations are performed for a commercially available ceramic heater element for two cases. In the first, a spherical surface is traced around the entire heater assembly and the total radiant power and net radiant efficiency is computed. In the second, 50 cm × 50 cm vertical planes are traced parallel to the front face of the heater assembly at distances between 10 cm and 50 cm and the in-plane power and efficiencies are computed. The results indicate that the radiant efficiencies are strongly dependant on the input power to the element and, for the in-plane efficiencies, depend on the distance from the heater.

Characterisation of a grooved heat pipe with an anodised surface

Science.gov (United States)

Solomon, A. Brusly; Ram Kumar, A. M.; Ramachandran, K.; Pillai, B. C.; Senthil Kumar, C.; Sharifpur, Mohsen; Meyer, Josua P.

2017-03-01

A grooved heat pipe (GHP) is an important device for managing heat in space applications such as satellites and space stations, as it works efficiently in the absence of gravity. Apart from the above application, axial GHPs are used in many applications, such as electronic cooling units for temperature control and permafrost cooling. Improving the performance of GHPs is essential for better cooling and thermal management. In the present study, the effect of anodization on the heat transfer characteristics of a GHP is studied with R600a as a working fluid. In addition, the effects of fill ratio, inclination angle and heat inputs on the heat transfer performance of a GHP are studied. Furthermore, the effect of heat flux on dimensional numbers, such as the Webber, Bond, Kutateladze and condensation numbers, are studied. The inclination angle, heat input and fill ratio of GHPs are varied in the range of 0°-90°, 25-250 W and 10-70 % respectively. It is found that the above parameters have a significant effect on the performance of a GHP. Due to the anodisation, the maximum enhancement in heat transfer coefficient at the evaporator is 39 % for a 90° inclination at a heat flux of 11 kW/m2. The reported performance enhancement of a GHP may be due to the large numbers of nucleation sites created by the anodisation process and enhancement in the capillary force due to the coating.

Simulation of a high efficiency multi-bed adsorption heat pump

International Nuclear Information System (INIS)

TeGrotenhuis, W.E.; Humble, P.H.; Sweeney, J.B.

2012-01-01

Attaining high energy efficiency with adsorption heat pumps is challenging due to thermodynamic losses that occur when the sorbent beds are thermally cycled without effective heat recuperation. The multi-bed concept described here enables high efficiency by effectively transferring heat from beds being cooled to beds being heated. A simplified lumped-parameter model and detailed finite element analysis are used to simulate a sorption compressor, which is used to project the overall heat pump coefficient of performance. Results are presented for ammonia refrigerant and a nano-structured monolithic carbon sorbent specifically modified for the application. The effects of bed geometry and number of beds on system performance are explored, and the majority of the performance benefit is obtained with four beds. Results indicate that a COP of 1.24 based on heat input is feasible at AHRI standard test conditions for residential HVAC equipment. When compared on a basis of primary energy input, performance equivalent to SEER 13 or 14 are theoretically attainable with this system. - Highlights: ► A multi-bed concept for adsorption heat pumps is capable of high efficiency. ► Modeling is used to simulate sorption compressor and overall heat pump performance. ► Results are presented for ammonia refrigerant and a nano-structured monolithic carbon sorbent. ► The majority of the efficiency benefit is obtained with four beds. ► Predicted COP as high as 1.24 for cooling is comparable to SEER 13 or 14 for electric heat pumps.

Stochastic weather inputs for improved urban water demand forecasting: application of nonlinear input variable selection and machine learning methods

Science.gov (United States)

Quilty, J.; Adamowski, J. F.

2015-12-01

Urban water supply systems are often stressed during seasonal outdoor water use as water demands related to the climate are variable in nature making it difficult to optimize the operation of the water supply system. Urban water demand forecasts (UWD) failing to include meteorological conditions as inputs to the forecast model may produce poor forecasts as they cannot account for the increase/decrease in demand related to meteorological conditions. Meteorological records stochastically simulated into the future can be used as inputs to data-driven UWD forecasts generally resulting in improved forecast accuracy. This study aims to produce data-driven UWD forecasts for two different Canadian water utilities (Montreal and Victoria) using machine learning methods by first selecting historical UWD and meteorological records derived from a stochastic weather generator using nonlinear input variable selection. The nonlinear input variable selection methods considered in this work are derived from the concept of conditional mutual information, a nonlinear dependency measure based on (multivariate) probability density functions and accounts for relevancy, conditional relevancy, and redundancy from a potential set of input variables. The results of our study indicate that stochastic weather inputs can improve UWD forecast accuracy for the two sites considered in this work. Nonlinear input variable selection is suggested as a means to identify which meteorological conditions should be utilized in the forecast.

Recent trends (2003-2013) of land surface heat fluxes on the southern side of the central Himalayas, Nepal

Science.gov (United States)

Amatya, Pukar Man; Ma, Yaoming; Han, Cunbo; Wang, Binbin; Devkota, Lochan Prasad

2015-12-01

Novice efforts have been made in order to study the regional distribution of land surface heat fluxes on the southern side of the central Himalayas utilizing high-resolution remotely sensed products, but these have been on instantaneous scale. In this study the Surface Energy Balance System model is used to obtain annual averaged maps of the land surface heat fluxes for 11 years (2003-2013) and study their annual trends on the central Himalayan region. The maps were derived at 5 km resolution using monthly input products ranging from satellite derived to Global Land Data Assimilation System meteorological data. It was found that the net radiation flux is increasing as a result of decreasing precipitation (drier environment). The sensible heat flux did not change much except for the northwestern High Himalaya and High Mountains. In northwestern High Himalaya sensible heat flux is decreasing because of decrease in wind speed, ground-air temperature difference, and increase in winter precipitation, whereas in High Mountains it is increasing due to increase in ground-air temperature difference and high rate of deforestation. The latent heat flux has an overall increasing trend with increase more pronounced in the lower regions compared to high elevated regions. It has been reported that precipitation is decreasing with altitude in this region. Therefore, the increasing trend in latent heat flux can be attributed to increase in net radiation flux under persistent forest cover and irrigation land used for agriculture.

Dynamics of the cross flow heat exchanger for heating purposes

Energy Technology Data Exchange (ETDEWEB)

Mueller, K [Karlsruhe Univ. (TH) (Germany, F.R.). Inst. fuer Mess- und Regelungstechnik mit Maschinenlaboratorium

1980-09-01

A series of publications is available on the dynamic behaviour of heat exchangers (or heat transmitters, respectively), the subject of which is to deal with direct methods or with refined starting models for this general theme. The bridging between both these manners of advance remained as a problem. The author tried in his own investigation to solve the problem, and indeed by the selection of the correct starting model. He succeeded in this way, in that he removed conceptually a finned pipe from an arbitrary place of a heat exchanger and, furthermore, cut out from this particular pipe an arbitrary section. This section now does not stand alone for itself because the processes, which occur upstream of this section at the air-side and the water-side, are the input quantities of the section, which changes them due to its static and dynamic behaviour and emits them again as output quantities. The author, therefore, treats at first the dynamic behaviour of the section, which is represented in a signal flow diagram and which is used to derive approximate solutions from it. Furthermore, the author discusses the evident derivation of the total behaviour of heat exchangers.

Increased synaptophysin is involved in inflammation-induced heat hyperalgesia mediated by cyclin-dependent kinase 5 in rats.

Directory of Open Access Journals (Sweden)

Hong-Hai Zhang

Full Text Available Mechanisms associated with cyclin-dependent kinase 5 (Cdk5-mediated heat hyperalgesia induced by inflammation remain undefined. This study was designed to examine whether Cdk5 mediates heat hyperalgesia resulting from peripheral injection of complete Freund's adjuvant (CFA in the spinal dorsal horns of rats by interacting with synaptophysin, a well known membrane protein mediating the endocytosis-exocytosis cycle of synaptic vesicles as a molecular marker associated with presynaptic vesicle membranes. The role of Cdk5 in mediating synaptophysin was examined through the combined use of behavioral approaches, imaging studies, and immunoprecipitation following CFA-induced inflammatory pain. Results showed that Cdk5 colocalized with both synaptophysin and soluble N-ethylmaleimide-sensitive factor (NSF attachment protein receptors (SNAREs consisting of VAMP-2, SNAP-25, and syntaxin 1A in spinal dorsal horn of rats. Increased synaptophysin expression of spinal cord horn neurons post intraplantar injection of CFA coincided with increased duration of heat hyperalgesia lasting from 6 h to 3 d. Intrathecal administration of roscovitine, a Cdk5 specific inhibitor, significantly depressed synaptophysin expression during peak heat hyperalgesia and heat hyperalgesia induced by peripheral injection of CFA. Data presented in this report indicated that calpain activity was transiently upregulated 6 h post CFA-treatment despite previous reports suggesting that calpain was capable of cleaving p35 into p25. Results from previous studies obtained by other laboratories demonstrated that significant changes in p35 expression levels within spinal cord horn neurons were not observed in the CFA-treated inflammatory pain model although significant upregulation of Cdk5 kinase was observed between 2 h to 7 d. Therefore, generation of p25 occurred in a calpain-independent fashion in a CFA-treated inflammatory pain model. Our results demonstrated that increased synaptophysin

SEAWAT-based simulation of axisymmetric heat transport.

Science.gov (United States)

Vandenbohede, Alexander; Louwyck, Andy; Vlamynck, Nele

2014-01-01

Simulation of heat transport has its applications in geothermal exploitation of aquifers and the analysis of temperature dependent chemical reactions. Under homogeneous conditions and in the absence of a regional hydraulic gradient, groundwater flow and heat transport from or to a well exhibit radial symmetry, and governing equations are reduced by one dimension (1D) which increases computational efficiency importantly. Solute transport codes can simulate heat transport and input parameters may be modified such that the Cartesian geometry can handle radial flow. In this article, SEAWAT is evaluated as simulator for heat transport under radial flow conditions. The 1971, 1D analytical solution of Gelhar and Collins is used to compare axisymmetric transport with retardation (i.e., as a result of thermal equilibrium between fluid and solid) and a large diffusion (conduction). It is shown that an axisymmetric simulation compares well with a fully three dimensional (3D) simulation of an aquifer thermal energy storage systems. The influence of grid discretization, solver parameters, and advection solution is illustrated. Because of the high diffusion to simulate conduction, convergence criterion for heat transport must be set much smaller (10(-10) ) than for solute transport (10(-6) ). Grid discretization should be considered carefully, in particular the subdivision of the screen interval. On the other hand, different methods to calculate the pumping or injection rate distribution over different nodes of a multilayer well lead to small differences only. © 2013, National Ground Water Association.

Probabilistic tectonic heat flow modeling for basin maturation: Assessment method and applications

NARCIS (Netherlands)

Wees, J.D. van; Bergen, F. van; David, P.; Nepveu, M.; Beekman, F.; Cloetingh, S.; Bonté, D.

2009-01-01

Tectonic modeling is often neglected in the basin modeling workflow and heat flow is most times considered a user input. Such heat flows can, therefore, result in erroneous basin modeling outcomes, resulting in false overoptimistic identification of prospective areas or failure to identify

A review on opportunities for the development of heat pump drying systems in South Africa

Directory of Open Access Journals (Sweden)

Thomas Kivevele

2014-05-01

Full Text Available Recently, it has been discovered that heat pump drying is an efficient method of drying for drying industries. Heat pumps deliver more heat during the drying process than the work input to the compressor. Heat pump drying is a more advanced method than the traditional South African industrial and agricultural drying methods, such as direct/indirect sunlight, wood burning, fossil fuel burning, electrical heating and diesel engine heating. Heat pump dryers provide high energy efficiency with controllable temperature, air flow and air humidity and have significant energy-saving potential. In the last decade the market for heat pump systems for water heating and space cooling/heating has grown in South Africa, but the development of heat pumps for industrial and agricultural drying is very slow. As a result of high increases in fossil fuel prices and electricity in South Africa, as well as the problem of CO2 emissions, green energy, energy saving and energy efficiency are imperative. The development of heat pump drying systems in South Africa is an efficient way to solve energy problems in drying applications as this technology is still in its infancy. We review studies on heat pump drying and compare the methods therein with the most common methods of drying in South Africa.

Irradiation versus methyl bromide fumigation or heating as procedures for increasing shelf life of dry date varieties

International Nuclear Information System (INIS)

El-Samahy, S.K.; Abd El-Hady, S.A.; Swailam, H.M.

2004-01-01

The objective of this study is to evaluate the use of irradiation as an alternative method and comparing it with the traditional methods such as fumigation and heating for increasing shelf life dry date varieties. two varieties of dry dates, Malakaby and Gandilla, were obtained from Aswan, Upper Egypt and were used in this study. The irradiation was carried out with different doses of gamma rays to select the recommended dose to increase shelf life of dry dates. The fumigated, heated and irradiated samples were stored at room temperature after packaging in polyethylene plus cloth bags. The date characteristics such as insect infestation percent, weight loss, microbiological analyses, and firmness and chemical analyses were evaluated. The results obtained indicated that irradiation as a procedure for insect disinfestation and increasing shelf life of dry dates was better than both fumigation and heating methods. Where, irradiation of date fruits at dose of 1.0 kGy inhibited the insect infestation and improved the microbial quality of the date fruits during storage up to 18 months. Adding cloths to polyethylene packages raised the percentage of intact dry date fruits

Input-output supervisor

International Nuclear Information System (INIS)

Dupuy, R.

1970-01-01

The input-output supervisor is the program which monitors the flow of informations between core storage and peripheral equipments of a computer. This work is composed of three parts: 1 - Study of a generalized input-output supervisor. With sample modifications it looks like most of input-output supervisors which are running now on computers. 2 - Application of this theory on a magnetic drum. 3 - Hardware requirement for time-sharing. (author) [fr

Radiofrequency Waves, Heating and Current Drive in Magnetically Confined Plasmas

Energy Technology Data Exchange (ETDEWEB)

Porkolab, M; Bonoli, P T; Temkin, R J [Plasma Science and Fusion Center, MIT, Cambridge, MA (United States); Pinsker, R I; Prater, R [General Atomics, San Diego, California (United States); Wilson, J R [Princeton Plasma Physics Laboratory, Princeton, NJ (United States)

2012-09-15

The need for supplementary heating of magnetically confined plasmas to fusion relevant temperatures ({approx}20 keV) has been recognized from the beginning of modern fusion plasma research. Although in tokamaks the plasmas are formed initially by ohmic heating (P{Omega}{approx}{eta}{sub R}j, where j is the current density and {eta}{sub R} is the resistivity) its effectiveness deteriorates with increasing temperature since the resistivity decreases as T{sub e}{sup -3/2}, and losses due to bremsstrahlung radiation increase as Z{sub eff}{sup 3} T{sub e}{sup 1/2} (where Z{sub eff} is the effective ion charge), and the plasma current cannot be raised to arbitrarily large values because of MHD stability limits. In addition, energy losses due to thermal conduction P{sub loss} are typically anomalously large compared to neoclassical predictions and the dependence on temperature is not well understood. Thus, the simplest form of steady state power balance indicates that losses due to radiation and heat conduction must be balanced by auxiliary heating of some form, P{sub aux}, which may simply be stated as P{sub {Omega}} + P{sub {alpha}} - P{sub loss} P{sub aux} where P{sub {alpha}} is the power input provided by alpha particles, which does not become significant until the temperature exceeds some tens of keV, depending on confinement and density. (author)

Flexible heat pipes with integrated bioinspired design

Directory of Open Access Journals (Sweden)

Chao Yang

2015-02-01

Full Text Available In this work we report the facile fabrication and performance evaluation of flexible heat pipes that have integrated bioinspired wick structures and flexible polyurethane polymer connector design between the copper condenser and evaporator. Inside the heat pipe, a bioinspired superhydrophilic strong-base-oxidized copper mesh with multi-scale micro/nano-structures was used as the wicking material and deionized water was selected as working fluid. Thermal resistances of the fabricated flexible heat pipes charged with different filling ratios were measured under thermal power inputs ranging from 2 W to 12 W while the device was bent at different angles. The fabricated heat pipes with a 30% filling ratio demonstrated a low thermal resistance less than 0.01 K/W. Compared with the vertically oriented straight heat pipes, bending from 30° up to 120° has negligible influence on the heat-transfer performance. Furthermore, repeated heating tests indicated that the fabricated flexible heat pipes have consistent and reliable heat-transfer performance, thus would have important applications for advanced thermal management in three dimensional and flexible electronic devices.

Responses of tree and insect herbivores to elevated nitrogen inputs: A meta-analysis

Science.gov (United States)

Li, Furong; Dudley, Tom L.; Chen, Baoming; Chang, Xiaoyu; Liang, Liyin; Peng, Shaolin

2016-11-01

Increasing atmospheric nitrogen (N) inputs have the potential to alter terrestrial ecosystem function through impacts on plant-herbivore interactions. The goal of our study is to search for a general pattern in responses of tree characteristics important for herbivores and insect herbivorous performance to elevated N inputs. We conducted a meta-analysis based on 109 papers describing impacts of nitrogen inputs on tree characteristics and 16 papers on insect performance. The differences in plant characteristics and insect performance between broadleaves and conifers were also explored. Tree aboveground biomass, leaf biomass and leaf N concentration significantly increased under elevated N inputs. Elevated N inputs had no significantly overall effect on concentrations of phenolic compounds and lignin but adversely affected tannin, as defensive chemicals for insect herbivores. Additionally, the overall effect of insect herbivore performance (including development time, insect biomass, relative growth rate, and so on) was significantly increased by elevated N inputs. According to the inconsistent responses between broadleaves and conifers, broadleaves would be more likely to increase growth by light interception and photosynthesis rather than producing more defensive chemicals to elevated N inputs by comparison with conifers. Moreover, the overall carbohydrate concentration was significantly reduced by 13.12% in broadleaves while increased slightly in conifers. The overall tannin concentration decreased significantly by 39.21% in broadleaves but a 5.8% decrease in conifers was not significant. The results of the analysis indicated that elevated N inputs would provide more food sources and ameliorate tree palatability for insects, while the resistance of trees against their insect herbivores was weakened, especially for broadleaves. Thus, global forest insect pest problems would be aggravated by elevated N inputs. As N inputs continue to rise in the future, forest

Experimental Analysis of the Effects of Inclination Angle and Working Fluid Amount on the Performance of a Heat Pipe

Science.gov (United States)

Mahdavi, Mahboobe; Tiari, Saeed; Qiu, Songgang

2016-11-01

Heat pipes are two-phase heat transfer devices, which operate based on evaporation and condensation of a working fluid inside a sealed container. In the current work, an experimental study was conducted to investigate the performance of a copper-water heat pipe. The performance was evaluated by calculating the corresponding thermal resistance as the ratio of temperature difference between evaporator and condenser to heat input. The effects of inclination angle and the amount of working fluid were studied on the equivalent thermal resistance. The results showed that if the heat pipe is under-filled with the working fluid, energy transferring capacity of the heat pipe decreases dramatically. However, overfilling heat pipe causes over flood and degrades heat pipe performance. The minimum thermal resistances were obtained for the case that 30% of the heat pipe volume was filled with working fluid. It was also found that in gravity-assisted orientations, the inclination angle does not have significant effect on the performance of the heat pipe. However, for gravity-opposed orientations, as the inclination angle increases, the temperature difference between the evaporator and condensation increases and higher thermal resistances are obtained. Authors appreciate the financial support by a research Grant from Temple University.

Dynamic Heat Supply Prediction Using Support Vector Regression Optimized by Particle Swarm Optimization Algorithm

Directory of Open Access Journals (Sweden)

Meiping Wang

2016-01-01

Full Text Available We developed an effective intelligent model to predict the dynamic heat supply of heat source. A hybrid forecasting method was proposed based on support vector regression (SVR model-optimized particle swarm optimization (PSO algorithms. Due to the interaction of meteorological conditions and the heating parameters of heating system, it is extremely difficult to forecast dynamic heat supply. Firstly, the correlations among heat supply and related influencing factors in the heating system were analyzed through the correlation analysis of statistical theory. Then, the SVR model was employed to forecast dynamic heat supply. In the model, the input variables were selected based on the correlation analysis and three crucial parameters, including the penalties factor, gamma of the kernel RBF, and insensitive loss function, were optimized by PSO algorithms. The optimized SVR model was compared with the basic SVR, optimized genetic algorithm-SVR (GA-SVR, and artificial neural network (ANN through six groups of experiment data from two heat sources. The results of the correlation coefficient analysis revealed the relationship between the influencing factors and the forecasted heat supply and determined the input variables. The performance of the PSO-SVR model is superior to those of the other three models. The PSO-SVR method is statistically robust and can be applied to practical heating system.

Historic and future increase in the global land area affected by monthly heat extremes

NARCIS (Netherlands)

Coumou, Dim; Robinson, Alexander

2013-01-01

Climatic warming of about 0.5 ° C in the global mean since the 1970s has strongly increased the occurrence-probability of heat extremes on monthly to seasonal time scales. For the 21st century, climate models predict more substantial warming. Here we show that the multi-model mean of the CMIP5

Originate: PC input processor for origen-S

International Nuclear Information System (INIS)

Bowman, S.M.

1994-01-01

ORIGINATE is a personal computer program developed at Oak Ridge National Laboratory to serve as a user-friendly interface for the ORIGEN-S isotopic generation and depletion code. It is designed to assist an ORIGEN-S user in preparing an input file for execution of light-water-reactor fuel depletion and decay cases. Output from ORIGINATE is a card-image input file that may be uploaded to a mainframe computer to execute ORIGEN-S in SCALE-4. ORIGINATE features a pull down menu system that accesses sophisticated data entry screens. The program allows the user to quickly set up an ORIGEN-S input file and perform error checking. This capability increases productivity and decreases chance of user error. (authors). 6 refs., 3 tabs

Modeling the ionosphere-thermosphere response to a geomagnetic storm using physics-based magnetospheric energy input: OpenGGCM-CTIM results

Directory of Open Access Journals (Sweden)

Connor Hyunju Kim

2016-01-01

Full Text Available The magnetosphere is a major source of energy for the Earth’s ionosphere and thermosphere (IT system. Current IT models drive the upper atmosphere using empirically calculated magnetospheric energy input. Thus, they do not sufficiently capture the storm-time dynamics, particularly at high latitudes. To improve the prediction capability of IT models, a physics-based magnetospheric input is necessary. Here, we use the Open Global General Circulation Model (OpenGGCM coupled with the Coupled Thermosphere Ionosphere Model (CTIM. OpenGGCM calculates a three-dimensional global magnetosphere and a two-dimensional high-latitude ionosphere by solving resistive magnetohydrodynamic (MHD equations with solar wind input. CTIM calculates a global thermosphere and a high-latitude ionosphere in three dimensions using realistic magnetospheric inputs from the OpenGGCM. We investigate whether the coupled model improves the storm-time IT responses by simulating a geomagnetic storm that is preceded by a strong solar wind pressure front on August 24, 2005. We compare the OpenGGCM-CTIM results with low-earth-orbit satellite observations and with the model results of Coupled Thermosphere-Ionosphere-Plasmasphere electrodynamics (CTIPe. CTIPe is an up-to-date version of CTIM that incorporates more IT dynamics such as a low-latitude ionosphere and a plasmasphere, but uses empirical magnetospheric input. OpenGGCM-CTIM reproduces localized neutral density peaks at ~ 400 km altitude in the high-latitude dayside regions in agreement with in situ observations during the pressure shock and the early phase of the storm. Although CTIPe is in some sense a much superior model than CTIM, it misses these localized enhancements. Unlike the CTIPe empirical input models, OpenGGCM-CTIM more faithfully produces localized increases of both auroral precipitation and ionospheric electric fields near the high-latitude dayside region after the pressure shock and after the storm onset

SO2 policy and input substitution under spatial monopoly

International Nuclear Information System (INIS)

Gerking, Shelby; Hamilton, Stephen F.

2010-01-01

Following the U.S. Clean Air Act Amendments of 1990, electric utilities dramatically increased their utilization of low-sulfur coal from the Powder River Basin (PRB). Recent studies indicate that railroads hauling PRB coal exercise a substantial degree of market power and that relative price changes in the mining and transportation sectors were contributing factors to the observed pattern of input substitution. This paper asks the related question: To what extent does more stringent SO 2 policy stimulate input substitution from high-sulfur coal to low-sulfur coal when railroads hauling low-sulfur coal exercise spatial monopoly power? The question underpins the effectiveness of incentive-based environmental policies given the essential role of market performance in input, output, and abatement markets in determining the social cost of regulation. Our analysis indicates that environmental regulation leads to negligible input substitution effects when clean and dirty inputs are highly substitutable and the clean input market is mediated by a spatial monopolist. (author)

Evaluating the Sensitivity of Agricultural Model Performance to Different Climate Inputs: Supplemental Material

Science.gov (United States)

Glotter, Michael J.; Ruane, Alex C.; Moyer, Elisabeth J.; Elliott, Joshua W.

2015-01-01

Projections of future food production necessarily rely on models, which must themselves be validated through historical assessments comparing modeled and observed yields. Reliable historical validation requires both accurate agricultural models and accurate climate inputs. Problems with either may compromise the validation exercise. Previous studies have compared the effects of different climate inputs on agricultural projections but either incompletely or without a ground truth of observed yields that would allow distinguishing errors due to climate inputs from those intrinsic to the crop model. This study is a systematic evaluation of the reliability of a widely used crop model for simulating U.S. maize yields when driven by multiple observational data products. The parallelized Decision Support System for Agrotechnology Transfer (pDSSAT) is driven with climate inputs from multiple sources reanalysis, reanalysis that is bias corrected with observed climate, and a control dataset and compared with observed historical yields. The simulations show that model output is more accurate when driven by any observation-based precipitation product than when driven by non-bias-corrected reanalysis. The simulations also suggest, in contrast to previous studies, that biased precipitation distribution is significant for yields only in arid regions. Some issues persist for all choices of climate inputs: crop yields appear to be oversensitive to precipitation fluctuations but under sensitive to floods and heat waves. These results suggest that the most important issue for agricultural projections may be not climate inputs but structural limitations in the crop models themselves.

Heat pipe dynamic behavior

Science.gov (United States)

Issacci, F.; Roche, G. L.; Klein, D. B.; Catton, I.

1988-01-01

The vapor flow in a heat pipe was mathematically modeled and the equations governing the transient behavior of the core were solved numerically. The modeled vapor flow is transient, axisymmetric (or two-dimensional) compressible viscous flow in a closed chamber. The two methods of solution are described. The more promising method failed (a mixed Galerkin finite difference method) whereas a more common finite difference method was successful. Preliminary results are presented showing that multi-dimensional flows need to be treated. A model of the liquid phase of a high temperature heat pipe was developed. The model is intended to be coupled to a vapor phase model for the complete solution of the heat pipe problem. The mathematical equations are formulated consistent with physical processes while allowing a computationally efficient solution. The model simulates time dependent characteristics of concern to the liquid phase including input phase change, output heat fluxes, liquid temperatures, container temperatures, liquid velocities, and liquid pressure. Preliminary results were obtained for two heat pipe startup cases. The heat pipe studied used lithium as the working fluid and an annular wick configuration. Recommendations for implementation based on the results obtained are presented. Experimental studies were initiated using a rectangular heat pipe. Both twin beam laser holography and laser Doppler anemometry were investigated. Preliminary experiments were completed and results are reported.

Distinct brain systems mediate the effects of nociceptive input and self-regulation on pain.

Directory of Open Access Journals (Sweden)

Choong-Wan Woo

2015-01-01

Full Text Available Cognitive self-regulation can strongly modulate pain and emotion. However, it is unclear whether self-regulation primarily influences primary nociceptive and affective processes or evaluative ones. In this study, participants engaged in self-regulation to increase or decrease pain while experiencing multiple levels of painful heat during functional magnetic resonance imaging (fMRI imaging. Both heat intensity and self-regulation strongly influenced reported pain, but they did so via two distinct brain pathways. The effects of stimulus intensity were mediated by the neurologic pain signature (NPS, an a priori distributed brain network shown to predict physical pain with over 90% sensitivity and specificity across four studies. Self-regulation did not influence NPS responses; instead, its effects were mediated through functional connections between the nucleus accumbens and ventromedial prefrontal cortex. This pathway was unresponsive to noxious input, and has been broadly implicated in valuation, emotional appraisal, and functional outcomes in pain and other types of affective processes. These findings provide evidence that pain reports are associated with two dissociable functional systems: nociceptive/affective aspects mediated by the NPS, and evaluative/functional aspects mediated by a fronto-striatal system.

The effect of particle size on the heat affected zone during laser cladding of Ni-Cr-Si-B alloy on C45 carbon steel

Science.gov (United States)

Tanigawa, Daichi; Abe, Nobuyuki; Tsukamoto, Masahiro; Hayashi, Yoshihiko; Yamazaki, Hiroyuki; Tatsumi, Yoshihiro; Yoneyama, Mikio

2018-02-01

Laser cladding is one of the most useful surface coating methods for improving the wear and corrosion resistance of material surfaces. Although the heat input associated with laser cladding is small, a heat affected zone (HAZ) is still generated within the substrate because this is a thermal process. In order to reduce the area of the HAZ, the heat input must therefore be reduced. In the present study, we examined the effects of the powdered raw material particle size on the heat input and the extent of the HAZ during powder bed laser cladding. Ni-Cr-Si-B alloy layers were produced on C45 carbon steel substrates in conjunction with alloy powders having average particle sizes of 30, 40 and 55 μm, while measuring the HAZ area by optical microscopy. The heat input required for layer formation was found to decrease as smaller particles were used, such that the HAZ area was also reduced.

Heat-accumulator increases the comfort in the passenger-compartment and the driving-safety. Latentwaermespeicher erhoeht den Fahrkomfort und die Fahrsicherheit

Energy Technology Data Exchange (ETDEWEB)

Blueher, P.

1991-10-01

The integration of a heat-accumulator into the coolant system can significantly increase the comfort in the passenger-compartment and contribute to an improvement of the driving-safety. The newly developed heat-accumulator provides the required amount of energy to allow for a rapid heating-up of the passenger-compartment after an engine-coldstart and to prevent misting of the windows, especially the windscreen. In developing the heat accumulator focus was especially pointed on the environmental protection by systematically using harmless and recycable materials. (orig.).