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1

Heat Transfer  

NSDL National Science Digital Library

Students explore heat transfer and energy efficiency using the context of energy efficient houses. They gain a solid understanding of the three types of heat transfer: radiation, convection and conduction, which are explained in detail and related to the real world. They learn about the many ways solar energy is used as a renewable energy source to reduce the emission of greenhouse gasses and operating costs. Students also explore ways in which a device can capitalize on the methods of heat transfer to produce a beneficial result. They are given the tools to calculate the heat transferred between a system and its surroundings.

Integrated Teaching And Learning Program

2

Effect of microfouling on heat-transfer efficiency  

SciTech Connect

Field experiments, performed at Keahole Point, Hawaii and in the Gulf of Mexico, were designed to determine the relationship between decreased heat transfer efficiency and the accumulation of corrosion and/or biofouling films on heat exchanger surfaces. The sample tubes were maintained under conditions simulating those of an Ocean Thermal Energy Conversion (OTEC) system and data from the two sites have been compared. Seawater flowed through 2.54 (internal diameter) metal tubes at approximately 1.8m sec/sup -1/. Four types of tubes were used: 5052 Aluminum (A1), Grade 2 titanium (Ti), 90-10 copper-nickel (Cu-Ni) and Allegheny-Ludlum 6X stainless ssteel (SS). All surfaces were colonized by microorganisms, though colonization of the Cu-Ni surface was initially retarded. Total film weight was greatest for the Al and Cu-Ni surfaces which were characterized by corrosion as well as microbial fouling. The total organic carbon: total nitrogen ratios of the fouling films from Ti, Al, SS and Cu-Ni, 4.2, 4.0, 4.8 and 7.9 respectively, remained constant throughout the experiment. The degradation of heat transfer efficiency due to the formation of fouling layers on Ti and SS is neither linear nor a simple exponential function. A microfouling model is proposed for corrosion-resistant surfaces that is consistent with field observations.

Little, B.; Berger, L.R.

1980-01-01

3

Efficient Heat and Mass Transfer Formulations for Oil Shale Retorting  

NASA Astrophysics Data System (ADS)

A mathematical model for oil shale retorting is described that considers kerogen pyrolysis, oil coking, residual carbon gasification, carbonate mineral decomposition, water-gas shift, and phase equilibria reaction. Reaction rate temperature-dependence is described by Arrhenius kinetics. Fractured rock is modeled as a bi-continuum consisting of fracture porosity in which advective and dispersive gas and heat transport occur, and rock matrix in which diffusive mass transport and thermal conduction occur. Heat transfer between fracture and matrix regions is modeled either by a partial differential equation for spherical conduction or by a linear first-order heat transfer formulation. Mass transfer is modeled in an analogous manner or assuming local equilibrium. First-order mass and heat transfer coefficients are computed by a theoretical model from fundamental rock matrix properties. The governing equations are solved using a 3-D finite element formulation. Simulations of laboratory retort experiments and hypothetical problems indicated thermal disequilibrium to be the dominant factor controlling retort reactions. Simulation accuracy was unaffected by choice of mass transfer formulation. However, computational effort to explicitly simulate diffusive mass transfer in the rock matrix increased computational effort by more than an order of magnitude compared with first-order mass transfer or equilibrium analyses. A first-order heat transfer approximation of thermal conduction can be used without significant loss of accuracy if the block size and/or heating rate are not too large, as quantified by a proposed dimensionless heating rate.

Parker, J. C.; Zhang, F.

2007-12-01

4

Surface heat transfer coefficient, heat efficiency, and temperature of pulsed solid-state lasers  

SciTech Connect

The temperature of solid-state lasers is a critical parameter. Efficiency and output power are strongly influenced by it. The two parameters which determine the temperature are the heat generation efficiency (HGE) and the surface heat transfer coefficient (SHTC) of the laser rod. These parameters allow the scaling of the rod temperature up to high pumping powers. Moreover, from the temperature inside the rod, the temperature gradients and the mechanical stress can be evaluated. Using transient temperature measurements, the SHTC and the HGE were determined for air- and water-cooled Nd:YAG and alexandrite lasers. The SHTC can be confirmed by theoretical considerations.

Mann, K.; Weber, H.

1988-08-01

5

EFFECT OF SQUEALER TIP ON ROTOR HEAT TRANSFER AND EFFICIENCY  

Microsoft Academic Search

Calculations were performed to simulate the tip flow and heat transfer on the GE-E 3 first stage turbine, which represents a modern gas turbine blade geometry. Cases considered were a smooth tip, 2% recess, and 3% recess. In addition a two-dimensional cavity problem was calculated. Good agreement with experimental results was obtained for the cavity calculations, demonstrating that the k-?

A. A. Ameri; E. Steinthorsson; David L. Rigby

1997-01-01

6

Effect of squealer tip on rotor heat transfer and efficiency  

Microsoft Academic Search

Calculations were performed to simulate the tip flow and heat transfer on the GE-E³ first-stage turbine, which represents a modern gas turbine blade geometry. Cases considered were a smooth tip, 2 percent recess, and 3 percent recess. In addition, a two-dimensional cavity problem was calculated. Good agreement with experimental results was obtained for the cavity calculations, demonstrating that the κ-

A. A. Ameri; E. Steinthorsson; D. L. Rigby

1998-01-01

7

Modelling Heat Transfer Efficiency in Forced Convection Reflow Ovens  

Microsoft Academic Search

The investigation of the forced convection heating efficiency in reflow soldering environment and its necessity was presented in our paper. The calculations are based on the mass stream changes on the surface of the circuit, which have high impact on the convection constant. But all important stream variables (scalar space of the density, vector space of the speed, rotation etc.)

B. Illes; O. Krammer; G. Harsanyi; Z. Illyefalvi-Vitez

2006-01-01

8

The effects of heat transfer on the exergy efficiency of an air-standard otto cycle  

NASA Astrophysics Data System (ADS)

The exergy analysis of an air-standard Otto cycle with heat transfer loss is analyzed by using finite-time thermodynamics. The results showed that the heat transfer loss is responsible for a significant destruction of exergy. It is also shown that exergy efficiency and maximum power output increase with decreasing heat transfer loss. The results obtained in this paper may provide useful information for the maximum work available.

zcan, Hakan

2011-05-01

9

The effects of heat transfer on the exergy efficiency of an air-standard otto cycle  

Microsoft Academic Search

The exergy analysis of an air-standard Otto cycle with heat transfer loss is analyzed by using finite-time thermodynamics.\\u000a The results showed that the heat transfer loss is responsible for a significant destruction of exergy. It is also shown that\\u000a exergy efficiency and maximum power output increase with decreasing heat transfer loss. The results obtained in this paper\\u000a may provide useful

Hakan zcan

2011-01-01

10

Effects of Tip Clearance and Casing Recess on Heat Transfer and Stage Efficiency in Axial Turbines.  

National Technical Information Service (NTIS)

Calculations were performed to assess the effect of the tip leakage flow on the rate of heat transfer to blade, blade tip and casing. The effect on exit angle and efficiency was also examined. Passage geometries with and without casing recess were conside...

A. A. Ameri D. L. Rigby E. Steinthorsson

1998-01-01

11

A computationally efficient model of convective heat transfer and solidification characteristics during keyhole mode laser welding  

NASA Astrophysics Data System (ADS)

Computationally efficient heat transfer models of keyhole mode laser welding ignore fluid flow in the gas, liquid, and the two phase solid-liquid regions. These models cannot be applied to high Peclet number systems where convective heat transfer affects weld pool geometry, cooling rate, and other weld attributes. Here we show that by synthesizing features of an existing model to determine keyhole shape and size with rigorous fluid flow and heat transfer calculations in the liquid and the two phase solid-liquid regions, important features of both high and low Peclet number systems can be satisfactorily simulated. The geometry of the keyhole is calculated by assuming thermal equilibrium at the gas/liquid interface and point by point heat balance at the keyhole wall. The heat transfer outside the vapor cavity is calculated by numerically solving the equations of conservation of mass, momentum, and energy. A vorticity based turbulence model is used to estimate the values of effective viscosity and effective thermal conductivity of the liquid metal in the weld pool. It is shown that the temperature profile and the weld pool shape and size depend strongly on the convective heat transfer for low thermal conductivity alloys like stainless steel. For high thermal conductivity aluminum alloys, on the other hand, convection does not play a significant role in determining the shape and size of the weld pool. The computed solidification parameters indicated that the solidification structure becomes less dendritic and coarser with the decrease in welding velocity. The results demonstrate that a numerically efficient convective heat transfer model of keyhole mode laser welding can significantly improve the current understanding of weld attributes for different materials with widely different thermal properties.

Rai, R.; Roy, G. G.; Debroy, T.

2007-03-01

12

Expansion efficiency of pulse tube in pulse tube refrigerator including shuttle heat transfer effect  

Microsoft Academic Search

This paper describes simple analysis of the pulse tube expansion efficiency. Four dimensionless operating parameters of pulse tube refrigerator are needed to express the enthalpy flow at the cold end of the pulse tube. In this analysis, the expansion efficiency is calculated from the ratio of the diathermic enthalpy flow (non-zero gas-to-wall heat transfer) to the adiabatic enthalpy flow (zero

Jeheon Jung; Sangkwon Jeong

2005-01-01

13

Heat transfer effects on the net work output and efficiency characteristics for an air-standard Otto cycle  

Microsoft Academic Search

Finite-time thermodynamic analysis of an air-standard Otto cycle is performed in this paper. The relation between net work output and efficiency of the cycle is derived. The maximum net work output and the corresponding efficiency bound of the cycle with heat transfer considerations are also found. Detailed numerical examples are given. The result obtained herein provides a guide to the

Lingen Chen; Chih Wu; Fengrui Sun; Shui Cao

1998-01-01

14

Heat transfer science and technology  

Microsoft Academic Search

This book presents the papers given at a conference on heat transfer. Topics considered at the conference included two-phase flow, freezing, heat flux, natural heat convection, forced heat convection, flow visualization, boiling heat transfer, condensation heat transfer, thermal radiation, heat and mass transfer in porous media, nuclear reaction heat transfer, combustion heat transfer, high-temperature heat transfer, heat exchangers, and industrial

1987-01-01

15

Heat-transfer material  

NASA Astrophysics Data System (ADS)

The present invention concerns heat transfer material used for heat transfer recording, especially heat transfer material providing good recorded images on a substrate of poor surface smoothness, and the images can be corrected by a liftoff correction tape that produces adhesive properties when heated.

Katayama, Masahito; Sato, Hiroshi; Takizawa, Yoshihisa; Asaoka, Masanobu; Fukuda, Tsugihiro

1991-07-01

16

Heat transfer - Denver 1985  

SciTech Connect

This Symposium Series volume contains AIChE-sponsored session papers accepted for presentation at the 23rd National Heat Transfer Conference. The papers are grouped under the headings of: Heat Transfer for Alternate Energy Technologies; Nuclear Plant Degraded Core Cooling; Direct Flux Solar Energy Process; Numerical Methods for Multiphase Flow System and Component Analysis; General Solar Heat Transfer; Thermal Analysis of Steam Generators; Heat Transfer in Glass; Heat and Mass Transfer During Fluidized Bed Combustion; Single- and Two-Phase Process Heat Transfer.

Farukhi, N.M.

1985-01-01

17

Heat transfer - Denver 1985  

Microsoft Academic Search

This Symposium Series volume contains AIChE-sponsored session papers accepted for presentation at the 23rd National Heat Transfer Conference. The papers are grouped under the headings of: Heat Transfer for Alternate Energy Technologies; Nuclear Plant Degraded Core Cooling; Direct Flux Solar Energy Process; Numerical Methods for Multiphase Flow System and Component Analysis; General Solar Heat Transfer; Thermal Analysis of Steam Generators;

Farukhi

1985-01-01

18

Development and Demonstration of a High Efficiency, Rapid Heating, Low NOx Alternative to Conventional Heating of Round Steel Shapes, Steel Substrate (Strip) and Coil Box Transfer Bars  

SciTech Connect

Direct Flame Impingement involves the use of an array of very high-velocity flame jets impinging on a work piece to rapidly heat the work piece. The predominant mode of heat transfer is convection. Because of the locally high rate of heat transfer at the surface of the work piece, the refractory walls and exhaust gases of a DFI furnace are significantly cooler than in conventional radiant heating furnaces, resulting in high thermal efficiency and low NOx emissions. A DFI furnace is composed of a successive arrangement of heating modules through or by which the work piece is conveyed, and can be configured for square, round, flat, and curved metal shapes (e.g., billets, tubes, flat bars, and coiled bars) in single- or multi-stranded applications.

Kurek, Harry; Wagner, John

2010-01-25

19

A new and applicable method to calculate mass and heat transfer coefficients and efficiency of industrial distillation columns containing structured packings  

Microsoft Academic Search

Most of the methods developed for efficiency estimation of distillation columns were based on the empirical mass transfer and hydraulic relations correlated to laboratory data. Therefore, these methods cannot estimate efficiency of industrial columns with sufficient accuracy. In this paper, a new and applicable method was developed for calculation of efficiency (and mass and heat transfer coefficients) of distillation columns

Hamidreza Sadeghifar; Ali Akbar Safe Kordi

2011-01-01

20

Heat transfer pipe  

Microsoft Academic Search

A heat transfer pipe for use in a heat exchanger such as air conditioner, freezer and boiler is disclosed wherein grooves are formed in the inner wall surface of the pipe, which are by far finer in size than the grooves that have been provided for the purpose of increasing the heat transfer area in general, and slanting relative to

K. Fujie; M. Itoh; T. Innami; H. Kimura; W. Nakayama; T. Yanagida

1977-01-01

21

Pipe Heat Transfer Calculation.  

National Technical Information Service (NTIS)

This is a group of computer programs to determine heat transfer of multiple pipe systems as well as to evaluate economics of underground heat distribution systems. ...Software Description: The system is written in the FORTRAN V programming language for im...

1973-01-01

22

Microscale Evaporation Heat Transfer  

Microsoft Academic Search

In this work, microscale evaporation heat transfer and capillary phenomena for ultra thin liquid film area are presented. The interface shapes of curved liquid film in rectangular minichannel and in vicinity of liquid-vapor-solid contact line are determined by a numerical solution of simplified conduction through liquid layer. The data of numerical calculation of local heat transfer in rectangular channel and

V. V. Kuznetsov; S. A. Safonov

23

Heat transfer in pipes  

Microsoft Academic Search

The heat transfer from hot water to a cold copper pipe in laminar and turbulent flow condition is determined. The mean flow through velocity in the pipe, relative test length and initial temperature in the vessel were varied extensively during tests. Measurements confirm Nusselt's theory for large test lengths in laminar range. A new equation is derived for heat transfer

T. Burbach

1985-01-01

24

Heat transfer in energy problems  

NASA Astrophysics Data System (ADS)

Results of recent research are presented concerning heat transfer in energy problems, including high-temperature heat transfer, high-flux heat transfer, high-performance heat transfer, heat transfer in nonconventional energy (power and propulsion) systems, and novel heat transfer techniques. Topics discussed include studies of full-coverage film cooling, radiative properties of metals and alloys at high temperature, critical heat flux conditions in high-quality boiling systems, heat transfer characteristics of the evaporation of a liquid droplet on heated surfaces, high-performance surfaces for non-boiling heat transfer, and high performance heat transfer surfaces for boiling and condensation. Also examined are high flux heat transfer in gaseous solid suspension flow, nuclear process heat applications of high temperature heat exchange, heat transfer considerations in the use of new energy resources, and high performance mist-cooled condensers for geothermal binary cycle plants. No individual items are abstracted in this volume

Mizushina, T.; Yang, W. J.

25

Investment casting heat transfer  

NSDL National Science Digital Library

Calculate temperature profile and Biot number in mixed conduction and convection/radiation heat transfer from liquid metal through a ceramic mold to the environment, and suggest a design change to reduce the probability of shattering due to thermal stress.

Powell, Adam C., IV

2004-12-15

26

Visualization of heat transfer  

NASA Astrophysics Data System (ADS)

A survey of recently published papers which describe new experimental methods for heat transfer visualization or the application of such methods for investigating heat transfer problems is presented. The study of surface flow patterns and wall temperature by the oil-flow technique, the naphthalene sublimation technique, and temperature-sensitive paints is considered. The use of tracer materials to visualize the flow field is discussed, and optical methods of visualizing the field are described, presenting photographic illustrations.

Merzkirch, W.

27

Convective heat transfer in planetary dynamo models  

Microsoft Academic Search

The magnetic fields of planets and stars are generated by the motions of electrically conducting fluids within them. These fluid motions are thought to be driven by convective processes, as internal heat is transported outward. The efficiency with which heat is transferred by convection is integral in understanding dynamo processes. Several heat transfer scaling laws have been proposed, but the

Eric M. King; Krista M. Soderlund; Ulrich R. Christensen; Johannes Wicht; Jonathan M. Aurnou

2010-01-01

28

Heat transfer of rhyniophytic plant axes  

Microsoft Academic Search

Heat transfer is important for plants being sedentary organisms and exposed fully or partly to direct sunlight. It comprises three different mechanisms: (1) emission of IR (infra-red) radiation, (2) heat conduction and convection (sensible heat) and (3) evaporative cooling by transpiration (latent heat). Transpiration has been shown to act as an efficient cooling device in the case of extant land

Anita Roth-Nebelsick

2001-01-01

29

Heat transfer within combusting droplets  

Microsoft Academic Search

The improvement of the basic understanding of heat transfer in sprays is a key point in many engineering applications. In this paper, the temperature field within combusting ethanol droplets in linear stream is investigated by the two-color laser induced fluorescence technique. Additionally, a heat transfer model within the droplet is developed, taking into account both heat conduction and heat advection

G. Castanet; F. Lemoine

2007-01-01

30

"Nanotechnology Enabled Advanced Industrial Heat Transfer Fluids"  

SciTech Connect

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

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

2008-06-12

31

Fireplace heat transfer apparatus  

SciTech Connect

Fireplace heat transfer apparatus includes a main inner panel assembly adapted to be positioned across any opening to a fireplace and an auxiliary outer panel assembly piotally mounted to the main assembly. The main assembly includes an inner transparent plate of glass and the auxiliary assembly includes an outer transparent plate of glass. The outer glass plate is thicker than the inner glass plate. The mounting relationship of the auxiliary frame to the main frame maintains the outer plate of glass in a spaced relationship to the inner plate of glass so as to define a heat transfer chamber between them. The auxiliary and main assemblies have respective frame structures which closes the chamber at its sides but provides the chamber with an open top and bottom for communicating the chamber with ambient air in the room surrounding the fireplace. By pivoting the auxiliary assembly about an axis defined across its lower end and relative to the main assembly the volume of the chamber may be changed in order to change the rate of convective thermosiphon flow of heated ambient air up through the chamber.

Taylor, Th. E.

1985-05-28

32

Thermodynamics of Flow Boiling Heat Transfer  

NASA Astrophysics Data System (ADS)

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

Collado, F. J.

2003-05-01

33

Heat transfer coefficient of cryotop during freezing.  

PubMed

Cryotop is an efficient vitrification method for cryopreservation of oocytes. It has been widely used owing to its simple operation and high freezing rate. Recently, the heat transfer performance of cryotop was studied by numerical simulation in several studies. However, the range of heat transfer coefficient in the simulation is uncertain. In this study, the heat transfer coefficient for cryotop during freezing process was analyzed. The cooling rates of 40 percent ethylene glycol (EG) droplet in cryotop during freezing were measured by ultra-fast measurement system and calculated by numerical simulation at different value of heat transfer coefficient. Compared with the results obtained by two methods, the range of the heat transfer coefficient necessary for the numerical simulation of cryotop was determined, which is between 9000 W/(m(2)K) and 10000 W/(m (2)K). PMID:23812315

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

2013-01-01

34

Conduction heat transfer solutions  

SciTech Connect

This text is a collection of solutions to a variety of heat conduction problems found in numerous publications, such as textbooks, handbooks, journals, reports, etc. Its purpose is to assemble these solutions into one source that can facilitate the search for a particular problem solution. Generally, it is intended to be a handbook on the subject of heat conduction. This material is useful for engineers, scientists, technologists, and designers of all disciplines, particularly those who design thermal systems or estimate temperatures and heat transfer rates in structures. More than 500 problem solutions and relevant data are tabulated for easy retrieval. There are twelve sections of solutions which correspond with the class of problems found in each. Geometry, state, boundary conditions, and other categories are used to classify the problems. A case number is assigned to each problem for cross-referencing, and also for future reference. Each problem is concisely described by geometry and condition statements, and many times a descriptive sketch is also included. At least one source reference is given so that the user can review the methods used to derive the solutions. Problem solutions are given in the form of equations, graphs, and tables of data, all of which are also identified by problem case numbers and source references.

VanSant, J.H.

1980-03-01

35

Heat transfer from internally heated hemispherical pools  

SciTech Connect

Experiments were conducted on heat transfer from internally heated ZnSO/sub 4/-H/sub 2/O pools to the walls of hemispherical containers. This experimental technique provides data for a heat transfer system that has to date been only theoretically treated. Three different sizes of copper hemispherical containers were used: 240, 280, 320 mm in diameter. The pool container served both as a heat transfer surface and as an electrode. The opposing electrode was a copper disk, 50 mm in diameter located at the top of the pool in the center. The top surface of the pool was open to the atmosphere.

Gabor, J.D.; Ellsion, P.G.; Cassulo, J.C.

1980-01-01

36

Preparation and heat transfer properties of nanoparticle-in-transformer oil dispersions as advanced energy-efficient coolants  

Microsoft Academic Search

Three kinds of nanofluids are prepared by dispersing Al2O3 and AlN nanoparticles-in-transformer oil. The thermal conductivity of the nanoparticleoil mixtures increases with particle volume fraction and thermal conductivity of the solid particle itself. The AlN nanoparticles at a volume fraction of 0.5% can increase the thermal conductivity of the transformer oil by 8% and the overall heat transfer coefficient by

C. Choi; H. S. Yoo; J. M. Oh

2008-01-01

37

Heat Transfer in Magma Bodies.  

National Technical Information Service (NTIS)

Analytical heat transfer techniques are used to relate geological surface evidence and observations to conditions that are likely to exist in magma chambers. Resulting information is to be used for improving estimates of commercial heat extraction rates. ...

H. C. Hardee D. W. Larson

1976-01-01

38

Heat Transfer: From Hot to Not  

NSDL National Science Digital Library

Students learn the fundamental concepts of heat transfer and heat of reaction. This includes concepts such as physical chemistry, an equation for heat transfer, and a basic understanding of energy and heat transfer.

Integrated Teaching and Learning Program, College of Engineering,

39

Pareto Efficiency with Costly Transfers.  

National Technical Information Service (NTIS)

The concept of Pareto efficiency, as ordinarily applied, implies that costless redistributive transfers are possible. This paper generalizes the concept to a simple case where transfers of a given good involve losses mesasurable in that good. The Pareto e...

K. J. Arrow

1979-01-01

40

Heat transfer enhancement in heat exchangers  

SciTech Connect

In the power generation industry, high performance heat exchangers are needed to promote substantial improvements in effective utilization of waste heat in low temperature heat recovery applications. High performance heat exchangers are also seriously needed in low temperature power and refrigeration cycles that operate on renewable base energy sources such as ocean thermal energy conversion, geothermal and solar energy systems. Presently, the excessively large heat transfer surface area requirements prohibit cost-effective use of these systems. This paper reports on the new and promising electrohydrodynamic (EHD) technique which has demonstrated impressive potential for enhancing heat transfer in heat exchangers involving single-phase or phase-change processes. This article provides a brief description of EHD operational principles, research advancements in EHD during the past decade, and potential future EHD applications of specific interest to the HVAC and R industry.

Ohadi, M.M.

1991-12-01

41

Heat transfer in energy conservation  

Microsoft Academic Search

Seventeen papers by various authors are presented. The topics discussed are the many areas of heat transfer in energy conservation systems such as new techniques for measurement of quantities related to heat loss and energy use; monitoring and control instrumentation; potential energy savings in commercial\\/residential communities; total system design for building envelopes; and heat storage systems. Individual papers are abstracted

R. J. Goldstein; D. Didion; R. Gopal; K. Kreider; R. Schoenhals

1977-01-01

42

Evaluation of high-efficiency heat-transfer techniques. Final report, 27 September 1978-30 September 1981  

SciTech Connect

Single enhanced boiling tubes perform up to an order of magnitude better than single plain tubes, depending strongly on the type of surface and physical properties and operating conditions of the liquid. It is most pronounced at low temperature differences, then decreases and eventually disappears with increase of the temperature difference. The heat flux for a plain tube bundle is considerably greater than that for a single plain tube. Enhanced and finned tube bundles produce appreciable augmentation in heat flux compared to an identical plain tube bundle. The effect usually has most practical significance at low ..delta..T. The augmentation for enhanced tube bundles is less than the augmentation for single tubes, due mainly to the relatively more pronounced convective transfer for plain tubes. Although the cost of enhanced tubes is always higher, their advantage lies not only in smaller units required but, most importantly, that enhanced tubes will produce nucleate boiling at very low temperature differences where plain tubes would not. (Thus, heat recovery is possible in cases which otherwise would have to be rejected). The advantages of enhanced boiling tubes are not only in smaller size of the exchangers, but, in process loops involving compressors, operation of the typical low temperature boiler/condenser at a lower temperature difference, thus resulting in substantial savings in compressor size and energy consumption. Increased application of enhanced boiling surfaces will be realized as less expensive techniques of manufacture become commercially available. Three abstracts are entered separately.

Yilmaz, S.; Palen, J.W.; Taborek, J.

1981-12-01

43

HEAT TRANSFER MEANS  

DOEpatents

A heat exchanger is adapted to unifomly cool a spherical surface. Equations for the design of a spherical heat exchanger hav~g tubes with a uniform center-to-center spining are given. The heat exchanger is illustrated in connection with a liquid-fueled reactor.

Fraas, A.P.; Wislicenus, G.F.

1961-07-11

44

Sodium Heat Transfer System Modeling.  

National Technical Information Service (NTIS)

The sodium heat transfer system of the International Energy Agency (IEA) Small Solar Power Systems (SSPS) Central Receiver System (CRS), which includes the heliostat field, receiver, hot and cold storage vessels, and sodium/water steam generator has been ...

A. F. Baker M. E. Fewell

1983-01-01

45

Heat transfer in internal combustion engines  

Microsoft Academic Search

A heat transfer model has been developed that uses quasi-steady heat flux relations to calculate the heat transfer from combustion gases through the cylinder wall to the coolant in an internal combustion engine. The treatment of convective heat transfer accounts for the physical problems of rotating and impinging axial flow inside the engine cylinder. The radiative heat transfer includes gas

C. S. Wang; G. F. Berry

1985-01-01

46

The luminosity and heat-transfer efficiencies in fireballs as a problem of the hypersonic gas dynamics  

NASA Astrophysics Data System (ADS)

The coefficient of transformation of the kinetic energy flow of air particles into the luminous flow is obtained from fireball observational data. The coefficient is dependent only on the fireball velocity over a wide range of fireball parameters. The coefficient values cannot explain the observed ablation of fireball-generating bodies for velocities under 20 km/s. The flow of air particles is probably the main source of the heating of the body in this case. For velocities over 40 km/s the fireball radiation flow to the body is substantially less than the flow to the outside space. The evaluation of the classical fireball luminous efficiency is still largely an indefinite procedure on account of the body fragmentation.

Kalenichenko, V. V.

2003-04-01

47

Efficient heating and domestic hot water apparatus  

SciTech Connect

An efficient, compact boiler system providing both heating water for heating an enclosed space, such as a home, and domestic hot water for washing and similar purposes, has a limited fluid capacity primary heating coil within a combustion chamber. The coil supplies heated water to a larger capacity storage boiler located directly below the primary boiler and connected to it by header pipes which themselves form a manifold into which the primary coil is connected. The storage boiler distributes the heated water through the heating system. An elongated secondary heating coil within the boiler heats the domestic hot water supply by heat transfer from the boiler water. The return header pipe discharges heated water directly into the interior loop of the secondary coil to quickly heat the domestic hot water when the burner is ''on''.

Gerstmann, J.; Pompei, F.

1980-09-16

48

Pipe Heat Transfer Calculation.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. Underground heat distribution systems for a complex of buildings have been widely used in the United States for the past several decades. Only recently underground c...

1983-01-01

49

Heat transfer in damaged material  

NASA Astrophysics Data System (ADS)

Fully coupled thermo-mechanical analysis of civil engineering problems is studied. The mechanical analysis is based on damage mechanics which is useful for modeling of behaviour of quasi-brittle materials, especially in tension. The damage is assumed to be isotropic. The heat transfer is assumed in the form of heat conduction governed by the Fourier law and heat radiation governed by the Stefan-Boltzmann law. Fully coupled thermo-mechanical problem is formulated.

Kruis, J.

2013-10-01

50

Efficient oblivious transfer protocols  

Microsoft Academic Search

1 Introduction Oblivious Transfer (OT) protocols allow one party, the sender,to transmit part of its inputs to another party, the chooser, in amanner that protects both of them: the sender is assured that thechooser does not receive more information than it is entitled,while the chooser is assured that the sender does not learn whichpart of the inputs it received. OT

Moni Naor; Benny Pinkas

2001-01-01

51

Nanofluid impingement jet heat transfer  

PubMed Central

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

2012-01-01

52

Boiling heat transfer in compact heat exchangers  

SciTech Connect

Small circular and noncircular channels are representative of flow passages in compact evaporators and condensers. This paper describes results of an experimental study on heat transfer to the flow boiling of refrigerant- 12 in a small circular tube of diameter = 2.46 mm. The objective of the study was to assess the effect of channel size on the heat transfer coefficient and to obtain additional insights relative to the heat transfer mechanisms. The flow channel was made of brass and had an overall length of 0.9 m. The channel wall was electrically heated, and temperatures were measured on the channel wall and in the bulk fluid stream. Voltage taps were located at the same axial locations as the stream thermocouples to allow testing over an exit quality range of 0.21 to 0.94 and a large range of mass flux (63 to 832 kg/m{sup 2}s) and heat flux (2.5 to 59 kW/m{sup 2}). Saturation pressure was nearly constant, averaging 0.82 MPa for most of the testing; a few test data were also taken at a constant lower pressure of 0.52 MPa. Local heat transfer coefficients were determined experimentally. Analysis provided additional support for the conclusion, arrived at from previous studies, that a nucleation mechanism dominates for flow boiling in small channels; nevertheless, a convective-dominant region was identified at very low values of wall superheat (<{approx}3{degrees}C). Previous flow boiling studies in small channels, that did not include wall superheats this low, did not encounter the convective dominant mechanism. Conversely, cryogenic studies at very low wall superheats ({approx}l{degree}C) did not encounter the nucleation dominant regime. The apparent discrepancy is explained by the results of this study.

Tran, T.N.; Wambsganss, M.W. [Argonne National Lab., IL (United States); France, D.M. [Illinois Univ., Chicago, IL (United States). Dept. of Mechanical Engineering

1994-12-31

53

Heat transfer in a pulsating heat pipe with open end  

Microsoft Academic Search

Heat transfer in the evaporator and condenser sections of a pulsating heat pipe (PHP) with open end is modeled by analyzing thin film evaporation and condensation. The heat transfer solutions are applied to the thermal model of the pulsating heat pipe and a parametric study was performed. The results show that the heat transfer in a PHP is mainly due

Yuwen Zhang; Amir Faghri

2002-01-01

54

Numerical methods in heat transfer  

NASA Astrophysics Data System (ADS)

Finite element methods in thermal problems are considered along with the automatic solution of thermal problems, the heat transfer simulation of composite devices, a comparison of two- and three-level integration schemes for nonlinear heat conduction, boundary elements in thermal problems, and boundary integral equations used to solve thermoelastic problems. Attention is given to a boundary solution approach for the dynamic problem of thermoviscoelasticity theory, thermal and stress analysis of composite nuclear fuel rods by numerical methods, approaches for dealing with moving boundaries in thermal problems, multidimensional integral phase change approximations for finite element conduction codes, and the effect of free convection on entry flow between horizontal parallel plates. Other topics explored are related to a finite element solution for freezing problems, coupled convective and conductive heat transfer in the analysis of dry rock geothermal sources, and heat flow modeling in underground coal liquefaction.

Lewis, R. W.; Morgan, K.; Zienkiewicz, O. C.

55

Fin effect and radiative heat transfer of the unheated region of an asymmetrically heated tube  

NASA Astrophysics Data System (ADS)

The heat transfer rate in an asymmetrically heated tube is enhanced by heat conduction within the tube wall, i.e., the fin effect of the unheated region. The fin effects of the unheated regions on heat transfer rates and the temperature distributions of circumferentially partially heated tubes were numerically obtained for this paper; the flow in a tube was assumed to be turbulent and the radiation from the tube wall was taken into account. The circumferential heat conduction within the wall, the radiative heat exchange between walls, and the size of the heated region, were seen to affect the fin efficiency of the unheated region. Without radiative heat transfer, the unheated region of the asymmetrically heated tube can be considered to be a straight fin which has a constant thickness and height. The fin efficiency of the unheated region is increased with the radiative heat transfer of the wall.

Satoh, Isao; Kurosaki, Yasuo

56

Heat transfer in aerospace propulsion  

Microsoft Academic Search

Presented is an overview of heat transfer related research in support of aerospace propulsion, particularly as seen from the perspective of the NASA Lewis Research Center. Aerospace propulsion is defined to cover the full spectrum from conventional aircraft power plants through the Aerospace Plane to space propulsion. The conventional subsonic\\/supersonic aircraft arena, whether commercial or military, relies on the turbine

Robert J. Simoneau; Robert C. Hendricks; Herbert J. Gladden

1988-01-01

57

Sodium heat transfer system modeling  

NASA Astrophysics Data System (ADS)

The sodium heat transfer system of the international energy agency (IEA) small solar power systems (SSPS) central receiver system (CRS), which includes the heliostat field, receiver, hot and cold storage vessels, and sodium/water steam generator was modeled. The computer code SOLTES (simulator of large thermal energy systems), was used to model this system. The results from SOLTES are compared to measured data.

Baker, A. F.; Fewell, M. E.

1983-11-01

58

Nuclear reactor safety heat transfer  

Microsoft Academic Search

Nuclear Reactor Safety Heat Transfer is presented in five major sections.The first section presents the background material placing nuclear power in perspective. Starting with a historical overview, followed by fundamental concepts of nuclear energy and the philosphy of risk, the first three chapters: give the reader a brief but thorough introduction to nuclear power generation; describe the different types of

O. C. Jr

1981-01-01

59

Experimental research on heat transfer of pulsating heat pipe  

NASA Astrophysics Data System (ADS)

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

Li, Jia; Yan, Li

2008-06-01

60

Pulse combustion engine and heat transfer system  

Microsoft Academic Search

A fluid heating and cooling system is described comprising in combination a pulse combustion heat engine, primary heat exchange means for transferring heat rejected by the heat engine to a primary fluid to be heated, and a heat pump system. The heat engine includes chamber means for pulse combustion of a fuel to provide combustion gases which have cyclic periods

R. J. Priem; M. R. Ghassemzadeh; J. C. Griffiths

1987-01-01

61

Efficient low-polluting systems for heat treating metals  

Microsoft Academic Search

As the price of energy has risen, the economics of processes for heat-treating metals have altered radically. Advanced energy-efficient heating systems curb costs, but they must be designed to satisfy increasingly stringent environmental standards. The minimization of the heat discharged to atmosphere by the flue gas and the recovery of the useful heat transferred to the charge during the heat

Wunning

1988-01-01

62

A study on a flexible wing with up-down vibration in a pulsating flow of cooling air to improve heat transfer efficiency  

NASA Astrophysics Data System (ADS)

We investigated a flexible wing that can function as a folding fan by vibrating smoothly on a heated surface, and the effects of this vibration on heat transfer. For flexible up-down vibrations of the wing in a pulsating flow, we propose a novel milli-scale flexible wing shape with a relatively large body and a narrow connecting leg. The shape was optimized such that its deformation became much larger at a low air flow. We performed two-way fluid-structure interaction analyses to predict performance, and an experimental validation was also conducted. The details of flow, heat transfer, and structural deformation are summarized qualitatively. Our results show that the heat transfer coefficient of a heated surface with a single flexible wing was approximately 11.3 % greater than that of a flat plate.

Park, Ki-Hong; Min, June Kee; Kim, Jin-Kyu; Park, Sang-Hu; Ha, Man Yeong

2013-06-01

63

A study on a flexible wing with up-down vibration in a pulsating flow of cooling air to improve heat transfer efficiency  

NASA Astrophysics Data System (ADS)

We investigated a flexible wing that can function as a folding fan by vibrating smoothly on a heated surface, and the effects of this vibration on heat transfer. For flexible up-down vibrations of the wing in a pulsating flow, we propose a novel milli-scale flexible wing shape with a relatively large body and a narrow connecting leg. The shape was optimized such that its deformation became much larger at a low air flow. We performed two-way fluid-structure interaction analyses to predict performance, and an experimental validation was also conducted. The details of flow, heat transfer, and structural deformation are summarized qualitatively. Our results show that the heat transfer coefficient of a heated surface with a single flexible wing was approximately 11.3 % greater than that of a flat plate.

Park, Ki-Hong; Min, June Kee; Kim, Jin-Kyu; Park, Sang-Hu; Ha, Man Yeong

2013-10-01

64

Heat Transfer by Vapor Transfer in Ventilated Snow  

Microsoft Academic Search

A method has been developed for determining the heat transfer due to vapor transfer in snow through which air is flowing in a direction parallel but opposite to the heat flow. The experimental technique consists in determining the effective diffusivity of water vapor through snow, Do, which was subsequently used to calculate the extent of heat transfer due to vapor

Yin-Chao Yen

1963-01-01

65

Pulse combustion engine and heat transfer system  

Microsoft Academic Search

A pulse combustion powered apparatus for heating and pressurizing fluids is described comprising in combination a pulse combustion heat engine, compressor means, and primary heat exchange means for transferring heat rejected by the heat engine to a primary fluid to be heated. The heat engine includes chamber means for pulse combustion of a fuel to provide combustion gases which have

R. J. Priem; M. R. Ghassemzadeh; J. C. Griffiths

1988-01-01

66

Debottlenecking using heat transfer enhancement  

SciTech Connect

Vertical thermosiphon reboilers (VTRs) and multiple-effect evaporators, used widely in the process industries, are difficult to debottleneck. As a result, process engineers usually wind up buying expensive replacement units when they need to increase VTR or multiple-effect-evaporator throughput. Flow in these units depends on the buoyancy created by vaporization. Flowrate is thus linked not only to heat transfer rate, but also to vaporization and frictional and static pressure loss. Since these factors are closely linked, changing one affects the others. In this article, using a simulation model that has been validated against actual reboiler performance data, the authors show how tube inserts can be used to enhance heat transfer and to debottleneck some of these types of units. They conclude the article by working out a sample debottlenecking for a typical feed-forward, multi-effect evaporator operating at low pressure, using the simulation.

Polly, G.T.; Gibbard, I. [Cal Gavin Ltd. Process Intensification Engineering, Inc., Alcester (United Kingdom); Pretty, B. [Veritech, Inc., Reston, VA (United States)

1998-05-01

67

Enhancement of Heat Transfer by Corona Wind.  

National Technical Information Service (NTIS)

The mechanism of heat transfer enhancement across solid gaseous interfaces by corona wind directed towards the heat transfer surface is investigated. Corona wind may adequately be described by the Navier-Stokes equations of motion. The Coulomb ion drag fo...

H. Kadete

1987-01-01

68

Boiling Heat Transfer to Halogenated Hydrocarbon Refrigerants  

NASA Astrophysics Data System (ADS)

The current state of knowledge on heat transfer to boiling refrigerants (halogenated hydrocarbons) in a pool and flowing inside a horizontal tube is reviewed with an emphasis on information relevant to the design of refrigerant evaporators, and some recommendations are made for future research. The review covers two-phase flow pattern, heat transfer characteristics, correlation of heat transfer coefficient, influence of oil, heat transfer augmentation, boiling from tube-bundle, influence of return bend, burnout heat flux, film boiling, dryout and post-dryout heat transfer.

Yoshida, Suguru; Fujita, Yasunobu

69

Pulse Combustion: Impinging Jet Heat Transfer Enhancement  

Microsoft Academic Search

A new method for convective heat transfer enhancement is described. The technique involves the use of a pulse combustor to generate a transient jet that impinges on a flat plate. Enhancements in convective heat transfer of a factor of up to 2.5, compared to a steady impinging jet at approximately the same Reynolds number, have been obtained. Heat transfer data

R A. EIBECK; J. O. KELLER; T. T. BRAMLETTE; D. J. SAILOR

1993-01-01

70

Heat transfer correlations for multilayer insulation systems  

Microsoft Academic Search

Multilayer insulation (MLI) blankets are extensively used in spacecrafts as lightweight thermal protection systems. Heat transfer analysis of MLI is sometimes too complex to use in practical design applications. Hence, for practical engineering design purposes, it is necessary to have simpler procedures to evaluate the heat transfer rate through MLI. In this paper, four different empirical models for heat transfer

C. K. Krishnaprakas; K. Badari Narayana; Pradip Dutta

2000-01-01

71

Efficient energy transfer from Si-nanoclusters to Er ions in silica induced by substrate heating during deposition  

SciTech Connect

This study investigates the influence of the deposition temperature T{sub d} on the Si-mediated excitation of Er ions within silicon-rich silicon oxide layers obtained by magnetron cosputtering. For T{sub d} exceeding 200 deg. C, an efficient indirect excitation of Er ions is observed for all as-deposited samples. The photoluminescence intensity improves gradually up to a maximum at T{sub d}=600 deg. C before decreasing for higher T{sub d} values. The effects of this ''growth-induced annealing'' are compared to those resulting from the same thermal budget used for the ''classical'' approach of postdeposition annealing performed after a room temperature deposition. It is demonstrated that the former approach is highly beneficial, not only in terms of saving time but also in the fourfold enhancement of the Er photoluminescence efficiency.

Cueff, Sebastien; Labbe, Christophe; Cardin, Julien; Doualan, Jean-Louis; Khomenkova, Larysa; Hijazi, Khalil; Rizk, Richard [Centre de Recherche sur les Ions, les Materiaux et la Photonique (CIMAP), ENSICAEN, CNRS, CEA/IRAMIS, Universite de Caen, 14050 CAEN Cedex (France); Jambois, Olivier; Garrido, Blas [Dept. Electronica, MIND-IN2UB, Universitat de Barcelona, Marti i Fanques 1, 08028 Barcelona, CAT (Spain)

2010-09-15

72

Heat transfer in GTA welding arcs  

NASA Astrophysics Data System (ADS)

Heat transfer characteristics of Gas Tungsten Arc Welding (GTAW) arcs with arc currents of 50 to 125 A and arc lengths of 3 to 11 mm were measured experimentally through wet calorimetry. The data collected were used to calculate how much heat reported to the cathode and anode and how much was lost from the arc column. A Visual Basic for Applications (VBA) macro was written to further analyze the data and account for Joule heating within the electrodes and radiation and convection losses from the arc, providing a detailed account of how heat was generated and dissipated within the system. These values were then used to calculate arc efficiencies, arc column voltages, and anode and cathode fall voltages. Trends were noted for variances in the arc column voltage, power dissipated from the arc column, and the total power dissipated by the system with changing arc length. Trends for variances in the anode and cathode fall voltages, total power dissipated, Joule heating within the torches and electrodes with changing arc current were also noted. In addition, the power distribution between the anode and cathode for each combination of arc length and arc current was examined. Keywords: Gas Tungsten Arc Welding, GTAW, anode fall, cathode fall, heat transfer, wet calorimetry

Huft, Nathan J.

73

heat in history Isaac Newton and Heat Transfer  

Microsoft Academic Search

An attempt is made to provide historical perspectives on the influences of Newton's law of cooling (1701) on the development of heat transfer theory. Newton's cooling law provides the first heat transfer formulation and is the formal basis of convective heat transfer. The cooling law was incorporated by Fourier (1822) as the convective boundary condition (Biot number) in his mathematical

K. C. Cheng; T. Fujii

1998-01-01

74

POLYMER ENGINEERING: The importance of heat transfer in polymer processing  

Microsoft Academic Search

Heat transfer plays a critical role in the processing of thermoplastic polymers, influencing capital costs, operating costs, production rates and product quality. Closer collaboration between scientists and engineers in this field would improve the efficiency of polymer processing operations

M. F. Edwards; D. I. Ellis

1982-01-01

75

Pool boiling heat transfer to electrolyte solutions  

Microsoft Academic Search

Pool boiling heat transfer coefficients were measured for solutions of salts with positive solubility in water. The effect of the dissolved salts on nucleation site density, bubble departure diameter and bubble frequency was also investigated. The results show that at low heat fluxes heat transfer coefficients can be considerably lower than corresponding values for distilled water. At high heat fluxes

M. Jamialahmadi; A. Helalizadeh; H. Mller-Steinhagen

2004-01-01

76

Heat Transfer in a Thermoacoustic Process  

ERIC Educational Resources Information Center

Thermoacoustic instability is defined as the excitation of acoustic modes in chambers with heat sources due to the coupling between acoustic perturbations and unsteady heat addition. The major objective of this paper is to achieve accurate theoretical results in a thermoacoustic heat transfer process. We carry out a detailed heat transfer analysis

Beke, Tamas

2012-01-01

77

Heat exchanger device and method for heat removal or transfer  

DOEpatents

Systems and methods for a forced-convection heat exchanger are provided. In one embodiment, heat is transferred to or from a thermal load in thermal contact with a heat conducting structure, across a narrow air gap, to a rotating heat transfer structure immersed in a surrounding medium such as air.

Koplow, Jeffrey P. (San Ramon, CA)

2012-07-24

78

Handbook of heat transfer applications (2nd edition)  

NASA Astrophysics Data System (ADS)

The applications of heat transfer in engineering problems are considered. Among the applications discussed are: mass transfer cooling; heat exchangers; and heat pipes. Consideration is also given to: heat transfer in nonNewtonian fluids; fluidized and packed beds; thermal energy storage; and heat transfer in solar collectors. Additional topics include: heat transfer in buildings; cooling towers and ponds; and geothermal heat transfer.

Rohsenow, W. M.; Hartnett, J. P.; Ganic, E. N.

79

Sodium heat transfer system modeling  

SciTech Connect

The sodium heat transfer system of the International Energy Agency (IEA) Small Solar Power Systems (SSPS) Central Receiver System (CRS), which includes the heliostat field, receiver, hot and cold storage vessels, and sodium/water steam generator has been modeled. The computer code SOLTES (Simulator of Large Thermal Energy Systems), developed by Sandia National Laboratories, was used to model this system. Based on data provided to Sandia by the IEA-SSPS/CRS project, the results from SOLTES are compared to measured data. The comparison between measured data and predictions from SOLTES is very good for the day evaluated.

Baker, A.F.; Fewell, M.E.

1983-01-01

80

Liquid metal heat transfer issues  

SciTech Connect

An alkali liquid metal cooled nuclear reactor coupled with an alkali metal Rankine cycle provides a practicable option for space systems/missions requiring power in the 1 to 100 MW(e) range. Thermal issues relative to the use of alkali liquid metals for this purpose are identified as these result from the nature of the alkali metal fluid itself, from uncertainties in the available heat transfer correlations, and from design and performance requirements for system components operating in the earth orbital microgravity environment. It is noted that, while these issues require further attention to achieve optimum system performance, none are of such magnitude as to invalidate this particular space power concept.

Hoffman, H.W.; Yoder, G.L.

1984-01-01

81

Liquid metal heat transfer issues  

NASA Astrophysics Data System (ADS)

An alkali liquid metal cooled nuclear reactor coupled with an alkali metal Rankine cycle provides a practicable option for space systems/missions requiring power in the multi-megawatt range. Thermal issues relative to the use of alkali liquid metals for this purpose are identified as these result from the nature of the alkali metal fluid itself, from uncertainties in the available heat transfer correlations, and from design and performance requirements for system components operating in the earth orbital microgravity environment. It is noted that, while these issues require further attention to achieve optimum system performance, none are of such magnitude as to invalidate this particular space power concept.

Hoffman, H. W.; Yoder, G. L.

82

Interlayer heat transfer in bilayer carrier systems  

NASA Astrophysics Data System (ADS)

We study theoretically how energy and heat are transferred between the two-dimensional layers of bilayer carrier systems due to the near-field interlayer carrier interaction. We derive the general expressions for interlayer heat transfer and thermal conductance. Approximation formulae and detailed calculations for semiconductor- and graphene-based bilayers are presented. Our calculations for GaAs, Si and graphene bilayers show that the interlayer heat transfer can exceed the electron-phonon heat transfer below the (system-dependent) finite crossover temperature. We show that disorder strongly enhances the interlayer heat transport and pushes the threshold toward higher temperatures.

Prunnila, Mika; Laakso, Sampo J.

2013-03-01

83

Heat Transfer at Small Grashof Numbers  

Microsoft Academic Search

Rough physical arguments suggest that the heat transfer from a body, immersed in a fluid, should be determined by the heat-conduction equation alone whenever the Grashof number, G, associated with the problem is small. However, heat-transfer rates predicted in this fashion are not always in accordance with the experimentally determined values. It is shown that, while convection is negligible in

J. J. Mahony

1957-01-01

84

Radiant heat transfer at high temperatures  

Microsoft Academic Search

The majority of methods of the radiant heat transfer theory is based on certain simplified assumptions of radiation properties. Approximate methods for the determination of radiant heat transfer at high temperatures are considered, giving attention to the thin-layer approximation, the 'gray' gas approximation, the radiant heat conduction approximation, the zonal method, and methods taking into account the frequency dependence of

L. M. Biberman

1974-01-01

85

Heat transfer 1990. Proceedings of the ninth international heat transfer conference  

Microsoft Academic Search

This book contains the proceedings of the Ninth International Heat Transfer Conference. Included in Volume 4 are the following chapters: Startup transient modeling of vapor flow in heat pipes, Heat transfer between a laminar free surface impirging jet and a composite disk, Modeling of some constant heat transfer coefficient phase change problems.

Hetsroni

1990-01-01

86

Third heat?transfer crisis with stepwise heat supply  

Microsoft Academic Search

The paper reports experimental results on heat-transfer crises with stepwise heat supply to a heater, in which the metastable liquid decomposes in the form of vaporization fronts. Data on the dynamics of heat-transfer crises under saturation and underheating conditions are given. It is shown that below the vapor formed during propagation of vaporization fronts, a liquid microlayer is absent.

B. P. Avksentyuk; V. V. Ovchinnikov

2001-01-01

87

Efficiency and Innovation in Transfer  

Microsoft Academic Search

The transfer literature includes a variety of seemingly conflicting perspec- tives. Some argue that transfer is rare; others argue that transfer is ubiqui- tous; still others worry that transfer is an unworkable concept. Is the transfer literature filled with inherently contradictory claims, or is there a framework that can help illuminate how and why the varied positions on transfer are

Daniel L. Schwartz; John D. Bransford; David Sears

2005-01-01

88

Evaporation heat transfer and pressure drop of refrigerant R-134a in a plate heat exchanger  

Microsoft Academic Search

Plate heat exchangers (PHE) have been widely used in food processing, chemical reaction processes, and other industrial applications for many years. Particularly, in the last 20 years plate heat exchangers have been introduced to the refrigeration and air conditioning systems as evaporators or condensers for their high efficiency and compactness. Here, the evaporation heat transfer coefficient and pressure drop for

Y.-Y. Yan; T.-F. Lin

1999-01-01

89

Twin reservoir heat transfer circuit  

SciTech Connect

This patent describes a heat transfer means comprising circuitry defining a closed flow path for working fluid; a primary circuit forming part of the path and having two ends at one of which the working fluid is at a high pressure and at the other of which the working fluid is at a low pressure. The circuitry defines a fluid supply reservoir and a fluid collection reservoir disposed respectively at the two ends; ejector means in the primary circuit; a drive fluid inlet, and exhaust outlet and a suction inlet provided on the ejector means. Also included are a branch circuit bridging a section of the primary circuit and an outlet end of the branch circuit connected to the suction inlet of the ejector means.

Urch, J.F.

1986-09-23

90

REVIEW OF THERMAL CONDUCTIVITY AND HEAT TRANSFER IN UO  

Microsoft Academic Search

The theories of heal transfer in insulators are viewed and discussed ; relevant to UO. As the rate of heat transfer from a reactor core is ; determined largely by the thermal conductivity of the fuuel, this coefficient is ; of paramount importance in improving the efficiency of an installation. There is ; no theoretical basis to expect small or

Tennery

1958-01-01

91

Industrial furnace with improved heat transfer  

SciTech Connect

This patent describes an industrial furnace for heating work which emits volatiles during heating. It comprises a generally cylindrical, closed end furnace section defining a sealable heat transfer chamber for heating work disposed therein; fan means for directing furnace atmosphere as a swirling wind mass about the interior of the furnace section over a portion thereof; heat means for heating the wind mass within the fan chamber; and an incineration track formed as a circumferentially extending groove about the exterior of the furnace section and in heat transfer relationship with and situated at least to extend about a portion of the fan chamber.

Hoetzl, M.; Lingle, T.M.

1992-07-07

92

Experimental investigation of heat transfer in a centrifugal heat pipe with an optimized layer of heat-transfer agent  

Microsoft Academic Search

This paper describes a technique and gives results of experimental investigations of special features of heat transfer in the evaporator and condenser sections of a centrifugal heat pipe with optimized thickness of the layer of heat transfer agent.

B. N. Krivosheev; M. P. Kukharskii; V. D. Portnov

1982-01-01

93

Heat transfer performance and exergetic optimization for solar receiver pipe  

Microsoft Academic Search

The basic physical model of solar receiver pipe with solar selective coating is established, and associated heat transfer and exergetic performances are analyzed and optimized. Because of the heat losses of natural convection and infrared radiation, the energy absorption efficiency has a maximum at optimal incident energy flux. As the pipe radius decreases or flow velocity rises, the wall temperature

Lu Jianfeng; Ding Jing; Yang Jianping

2010-01-01

94

Advanced turbine cooling, heat transfer, and aerodynamic studies  

SciTech Connect

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

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

1995-12-31

95

Thermodynamics of flame impingement heat transfer  

NASA Astrophysics Data System (ADS)

A theoretical model for entropy generation and utilization of work potential (exergy) in flame impingement (both premixed and diffusion) heat transfer has been developed in this article, to offer physical insights on the optimal operational regimes, depicting high values of the surface heat flux with minimal exergy destruction, within the practical constraints. The irreversibility components due to different physical processes have been evaluated from a general entropy transport equation. The velocity, temperature, and species concentration fields required for the solution of entropy transport equation have been determined from the numerical computation of flow-field in the flame. Global two-step chemical kinetics has been considered with methane (CH4) and air as fuel and oxidizer, respectively. The results have been predicted in terms of average nondimensional heat flux, expressed as Nusselt number at the target plate, the irreversibility components, and second law efficiency, as functions of the pertinent input parameters such as the jet Reynolds number and the ratio of plate separation distance to nozzle diameter (H/d). The average Nusselt number has been found to increase with an increase in jet Reynolds number and a decrease in H/d ratio, up to a value of 8. The dominant source of thermodynamic irreversibility in a premixed flame has been attributed to the thermal energy exchange whereas, in a diffusion flame, the same has been attributed to an uncontrolled exchange of electrons accompanying the reactive kinetics. The second law efficiency has been found to increase with an increase in jet Reynolds number and an increase in the H/d ratio, up to a value of 20. Values of the jet Reynolds number greater than 10 000 and H/d ratio in the tune of 15 have been observed to pertain to the regime of optimum flame impingement heat transfer, consistent with the energy and exergy balance constraints.

Som, S. K.; Agrawal, G. K.; Chakraborty, Suman

2007-08-01

96

Heat Transfer Augmentation in a Compact Heat Exchange Pedestal Array.  

National Technical Information Service (NTIS)

A compact heat exchanger pedestal array for augmenting heat transfer in a machine is disclosed. The compact heat exchanger pedestal array includes a wall having first and second surfaces. The first surface faces a heated flow path and the second surface p...

C. R. Joe P. M. Lutjen

2004-01-01

97

Heat transfer in an unevenly heated porous layer  

Microsoft Academic Search

For a uniform saturated porous layer heated from below, the dependence of the quantity of heat transferred on the distribution\\u000a of the heat source is investigated. It is found, using perturbation methods and numerical techniques, that very small nonuniformities\\u000a in the heat source having the same wavelength as the preferred convection mode significantly reinforce natural convection.

M. J. O'Sullivan; R. McKibbin

1986-01-01

98

Efficient Phase-Change Materials: Development of a Low-Cost Thermal Energy Storage System Using Phase-Change Materials with Enhanced Radiation Heat Transfer  

SciTech Connect

HEATS Project: USF is developing low-cost, high-temperature phase-change materials (PCMs) for use in thermal energy storage systems. Heat storage materials are critical to the energy storage process. In solar thermal storage systems, heat can be stored in these materials during the day and released at nightwhen the sun is not outto drive a turbine and produce electricity. In nuclear storage systems, heat can be stored in these materials at night and released to produce electricity during daytime peak-demand hours. Most PCMs do not conduct heat very well. Using an innovative, electroless encapsulation technique, USF is enhancing the heat transfer capability of its PCMs. The inner walls of the capsules will be lined with a corrosion-resistant, high-infrared emissivity coating, and the absorptivity of the PCM will be controlled with the addition of nano-sized particles. USFs PCMs remain stable at temperatures from 600 to 1,000C and can be used for solar thermal power storage, nuclear thermal power storage, and other applications.

None

2011-12-05

99

Single nozzle spray cooling heat transfer mechanisms  

Microsoft Academic Search

An investigation into single nozzle spray cooling heat transfer mechanisms with varying amounts of dissolved gas was performed using two powerful techniques. Time and space resolved heat transfer distributions produced by a single nozzle were measured using an array of individually controlled microheaters, while visualization and measurements of the liquidsolid contact area and the three-phase contact line length were made

Bohumil Horacek; Kenneth T. Kiger; Jungho Kim

2005-01-01

100

PRELIMINARY RESULTS ON FLINAK HEAT TRANSFER  

Microsoft Academic Search

Heat transfer coefficients have been measured for flinak flowing ; turbulently in both Ni and inconel tubes. The data obtained using the Ni tube ; lie in the hydrodynamic transition region and substantially check the heat ; transfer correlation for most ordinary fluids. The inconel tube data fall ; considerably below the expected correlation. It is believed that this ;

Hoffman

1953-01-01

101

ON THE STABILITY OF BOILING HEAT TRANSFER  

Microsoft Academic Search

Boiling heat transfer in the nucleate region is reviewed. The ; transition film-boiling region is analyzed by considering the stability of a ; plane vortex sheet separating two inviscid fluids. Using the classical results ; of Helmholtz Kelvan and Rayleigh expressions have been derived that predict the ; maximum and minimum heat-transfer rates in the nucleate and the film-boiling ;

N. Zuber

1958-01-01

102

Numerical study of local heat transfer coefficient and fin efficiency of wavy fin-and-tube heat exchangers ? ? The present work is supported by the National Science Fund for Distinguished Young Scholars from the National Natural Science Foundation of China (No. 50425620), and the Key Grant Project of Chinese Ministry of Education (No. 306014)  

Microsoft Academic Search

Three-dimensional numerical simulations were performed for laminar flow of wavy fin-and-tube heat exchangers by using body-fitted coordinates (BFC) method with fin efficiency effect accounted. The prediction results of average Nusselt number, friction factor and fin efficiency were compared with the related experimental correlations [R.C. Xin, H.Z. Li, H.J. Kang, W. Li, W.Q. Tao, An experimental investigation on heat transfer and

Y. B. Tao; Y. L. He; J. Huang; Z. G. Wu; W. Q. Tao

2007-01-01

103

Heat Transfer in Complex Fluids  

SciTech Connect

Amongst the most important constitutive relations in Mechanics, when characterizing the behavior of complex materials, one can identify the stress tensor T, the heat flux vector q (related to heat conduction) and the radiant heating (related to the radiation term in the energy equation). Of course, the expression 'complex materials' is not new. In fact, at least since the publication of the paper by Rivlin & Ericksen (1955), who discussed fluids of complexity (Truesdell & Noll, 1992), to the recently published books (Deshpande et al., 2010), the term complex fluids refers in general to fluid-like materials whose response, namely the stress tensor, is 'non-linear' in some fashion. This non-linearity can manifest itself in variety of forms such as memory effects, yield stress, creep or relaxation, normal-stress differences, etc. The emphasis in this chapter, while focusing on the constitutive modeling of complex fluids, is on granular materials (such as coal) and non-linear fluids (such as coal-slurries). One of the main areas of interest in energy related processes, such as power plants, atomization, alternative fuels, etc., is the use of slurries, specifically coal-water or coal-oil slurries, as the primary fuel. Some studies indicate that the viscosity of coal-water mixtures depends not only on the volume fraction of solids, and the mean size and the size distribution of the coal, but also on the shear rate, since the slurry behaves as shear-rate dependent fluid. There are also studies which indicate that preheating the fuel results in better performance, and as a result of such heating, the viscosity changes. Constitutive modeling of these non-linear fluids, commonly referred to as non-Newtonian fluids, has received much attention. Most of the naturally occurring and synthetic fluids are non-linear fluids, for example, polymer melts, suspensions, blood, coal-water slurries, drilling fluids, mud, etc. It should be noted that sometimes these fluids show Newtonian (linear) behavior for a given range of parameters or geometries; there are many empirical or semi-empirical constitutive equations suggested for these fluids. There have also been many non-linear constitutive relations which have been derived based on the techniques of continuum mechanics. The non-linearities oftentimes appear due to higher gradient terms or time derivatives. When thermal and or chemical effects are also important, the (coupled) momentum and energy equations can give rise to a variety of interesting problems, such as instability, for example the phenomenon of double-diffusive convection in a fluid layer. In Conclusion, we have studied the flow of a compressible (density gradient type) non-linear fluid down an inclined plane, subject to radiation boundary condition. The heat transfer is also considered where a source term, similar to the Arrhenius type reaction, is included. The non-dimensional forms of the equations are solved numerically and the competing effects of conduction, dissipation, heat generation and radiation are discussed. It is observed that the velocity increases rapidly in the region near the inclined surface and is slower in the region near the free surface. Since R{sub 7} is a measure of the heat generation due to chemical reaction, when the reaction is frozen (R{sub 7}=0.0) the temperature distributions would depend only on R{sub 1}, and R{sub 2}, representing the effects of the pressure force developed in the material due to the distribution, R{sub 3} and R{sub 4} viscous dissipation, R{sub 5} the normal stress coefficient, R{sub 6} the measure of the emissivity of the particles to the thermal conductivity, etc. When the flow is not frozen (RP{sub 7} > 0) the temperature inside the flow domain is much higher than those at the inclined and free surfaces. As a result, heat is transferred away from the flow toward both the inclined surface and the free surface with a rate that increases as R{sub 7} increases. For a given temperature, an increase in {zeta} implies that the activation energy is smaller and thus, the reaction ra

Mehrdad Massoudi

2012-01-01

104

Containment condensing heat transfer. [PWR; BWR  

SciTech Connect

This report presents a mechanistic heat-transfer model that is valid for large scale containment heat sinks. The model development is based on the determination that the condensation is controlled by mass diffusion through the vapor-air boundary layer, and the application of the classic Reynolds' analogy to formulate expressions for the transfer of heat and mass based on hydrodynamic measurements of the momentum transfer. As a result, the analysis depends on the quantification of the shear stress (momentum transfer) at the interface between the condensate film and the vapor-air boundary layer. In addition, the currently used Tagami and Uchida test observations and their range of applicability are explained.

Gido, R.G.; Koestel, A.

1983-01-01

105

Heat transfer in rotor/stator cavity  

NASA Astrophysics Data System (ADS)

In the paper we analyze the results of DNS/LES of the flow with heat transfer in the rotor/stator cavity. The rotor and the outer cylinder are heated. Computations have been performed for wide range of Reynolds numbers and aspect ratios. Computations are based on the efficient pseudo-spectral Chebyshev-Fourier method. In LES we used a Lagrangian dynamic subgrid-scale model of turbulence. Analysis allowed to check the influence of the aspect ratio and Reynolds number on the statistics and the structure of the flow. We analyzed all six Reynolds stress tensor components, turbulent fluctuations, three turbulent heat fluxes and different structural parameters which can be useful for modeling purposes. The distributions of Nusselt numbers obtained for different Re and aspect rations along disks are given. We also investigated influence of thermal Rosssby number as well as distributions of temperature along heated disk on statistics. Computations have shown that turbulence is mostly concentrated in the stator boundary layer with a maximum at the junction between the stator and the outer cylinder. The results are compared to the experimental and numerical data taken from literature.

Tuliszka-Sznitko, Ewa; Majchrowski, Wojciech; Kie?czewski, Kamil

2011-12-01

106

Third heat transfer crisis at subcooling  

Microsoft Academic Search

The effect of liquid subcooling below the saturation temperature on the third heat transfer crisis was studied experimentally\\u000a at pool boiling. Experimental data on the threshold values of superheating and heat fluxes, above which the evaporation front\\u000a and third heat transfer crisis for acetone at subcooling from 0.3 to 10 K are formed, were shown. Formation of evaporation\\u000a fronts is

B. P. Avksentyuk; V. V. Ovchinnikov

2008-01-01

107

Heat transfer characteristics of rotating triangular thermosyphon  

NASA Astrophysics Data System (ADS)

An experimental investigation is carried out to study heat transfer characteristics of a rotating triangular thermosyphon, using R-134a refrigerant as the working fluid. The tested thermosyphon is an equilateral triangular tube made from copper material of 11 mm triangular length, 2 mm thickness, and a total length of 1,500 mm. The length of the evaporator section is 600 mm, adiabatic section is 300 mm, and condenser section is 600 mm. The effects of the rotational speed, filling ratio, and the evaporator heat flux on each of the evaporator heat transfer coefficient, he, condenser heat transfer coefficient, hc, and the overall effective thermal conductance, Ct are studied. Experiments are performed with a vertical position of thermosyphon within heat flux ranges from 11 to 23 W/m2 for the three selected filling ratios of 10, 30 and 50 % of the evaporator section volume. The results indicated that the maximum values of the tested heat transfer parameters of the rotational equilateral triangular thermosyphon are obtained at the filling ratio of 30 %. Also, it is found that the heat transfer coefficient of the condensation is increased with increasing the rotational speed. The tested heat transfer parameters of the thermosyphon are correlated as a function of the evaporator heat flux and angular velocity.

Ibrahim, E.; Moawed, M.; Berbish, N. S.

2012-09-01

108

SIMPLIFIED METHOD FOR UNDERGROUND HEAT TRANSFER CALCULATION  

Microsoft Academic Search

A simplified heat transfer calculation method for underground buildings is developed. The method is based on the results from the ITPE method and is suitable for seasonal heat loss calculation. The simplified method consists of a set of equations for estimating the monthly total heat flow between an underground building and ground as a function of a wide range of

Sangho Choi; Moncef Krarti

109

Description, calibration, and preliminary testing of the coal liquefaction heat transfer coefficient measurement test unit  

Microsoft Academic Search

The efficiency of energy utilization within coal-liquefaction process is of major significance to the commercialization of the process. Heat exchange equipment is also one of the major economic investments in new plants. Consequently, reliable heat transfer data are required for the economical design of heat exchange equipment. Since accurate heat transfer coefficients of coal slurries, especially with a gas phase

T. P. Mulcahey; R. N. K. Lo; T. R. Bump; M. E. Mulcahey; J. Fischer; T. F. Cannon; R. E. Brock; W. I. Wilson; D. Bowyer

1979-01-01

110

Droplet heat transfer and chemical reactions during direct containment heating  

SciTech Connect

A simplified model of heat transfer and chemical reaction has been adapted to evaluate the expected behavior of droplets containing unreacted Zircaloy and stainless steel moving through the containment atmosphere during postulated accidents involving direct containment heating. The model includes internal and external diffusive resistances to reaction. The results indicate that reactions will be incomplete for many conditions characteristic of direct containment heating sequences.

Baker, L. Jr.

1986-01-01

111

Heat transfer characteristics of a gas-to-gas heat exchanger using heat pipes  

Microsoft Academic Search

The heat transfer characteristics of a gas-to-gas heat exchanger employing heat pipes as the heat transfer elements were examined. Experimental data obtained on the heat exchanger containing 66 finned heat pipes were compared with the values calculated by using various empirical and theoretical equations. A basic design procedure for gas-to-gas heat exchangers using heat pipes was then established. The results

Y. Wakiyama; K. Harada; S. Inoue; J. Fujita; H. Suematsu

1978-01-01

112

EHD (Electrohydrodynamics) enhancement of heat transfer in heat exchangers  

NASA Astrophysics Data System (ADS)

The potential of using an electric field with negligible power consumption (the corona discharge) to enhance corrective heat transfer coefficients for air flow in straight tubes was investigated experimentally. Pressure drop and heat transfer measurements were performed for Reynolds numbers and for electrode potentials. The effects were studied in the presence of both negative and positive corona fields. Based on the results obtained, a maximum of 215 percent enhancement in heat transfer coefficients at Reynolds number of Re sub D = 2000 and at field potential of 0 = 7.75 kV was obtained.

Nelson, D. A.; Ohadi, M. M.

1988-08-01

113

Heat transfer characteristics of two-phase thermosyphon heat pipe. I - Boiling heat transfer correlation in heating section  

Microsoft Academic Search

A correlation for the boiling heat transfer coefficient in the heating section of a two-phase thermosyphon heat pipe is developed in comparison with experimental data. The experiments are conducted for a vertically oriented thermosyphon pipe using three kinds of working fluid, water, Feron R 113, and ethanol, at a wide pressure range of 0.1 to 20 bar and a fill

Fumito Kaminaga; Yoshizo Okamoto

1992-01-01

114

Convective heat transfer in hypobaric environments  

NASA Astrophysics Data System (ADS)

The relationship between convective heat transfer and barometric pressure (P sub b), specifically, how hypobaric pressure affects the convective heat transfer coefficient (H sub c) is examined. Five environmental conditions were simulated at elevation of 0 (sea level), 1520 m (5000 ft), 3050 m (10,000 ft), 4570 m (15,000 ft), and 6100 m (20,000 ft). In the chamber, constant temperature (30 C) and wind speed (0.5m/s) were maintained. The convective heat transfer coefficient was determined using the naphthalene sublimation technique. Circular naphthalene disks were affixed to six sites on a stationary copper manikin. The amount of naphthalene weight loss through sublimation was translated to H(sub c) using the Chilton-Colburn j-factor analogy between heat and mass transfer. As elevation increases, P(sub b) decreases; H(sub c) should decrease accordingly, pointing to a diminished convective heat transfer mechanism. Hitherto, the relationship between H(sub c) and P(sub b) was thought to be a nonlinear power function. The results showed that convective transfer indeed decreased at higher elevation, but H(sub c) and (sub b) exhibit a linear relationship. A linear relationship was also obtained from a theoretical derivation. These results suggest that in a hypobaric environment, the convective transfer process becomes even more diminished, and the potential convective heat loss is smaller than the original nonlinear theory would predict.

Chang, Stephen Kw.; Gonzalez, Richard R.

1989-07-01

115

Transient Heat Transfer in Coated Superconductors.  

National Technical Information Service (NTIS)

Computer simulation of transient heat transfer from coated superconductors to liquid helium have revealed that coating a superconductor with certain new materials, called Laketites, instead of traditional insulation, such as GE7031, substantially improves...

A. R. Menard

1982-01-01

116

Heat Transfer Mediums les Fluides Caloporteurs.  

National Technical Information Service (NTIS)

Different mediums (gas, vapor, liquid) most commonly employed in industry for heat transfer are discussed. Data pertaining to the various properties of these mediums are presented. Criteria for choosing a medium are given together with the medium most com...

J. P. Allard

1977-01-01

117

Heat Transfer Characteristics of Turbotec Tubing.  

National Technical Information Service (NTIS)

This survey and evaluation of the thermal/hydraulic performance of Turbotec spirally fluted tubes considers the data available in the form of technical papers and company reports through 1979. The emphasis is on individual heat transfer coefficients for t...

A. E. Bergles

1980-01-01

118

Infrared Radiative Heat Transfer in Nongray Gases.  

National Technical Information Service (NTIS)

The object of this investigation was to study various approximate methods of analyzing infrared radiative heat transfer in nongray nonisothermal gases. For this purpose, a very simple physical system was chosen consisting of a gas bounded by two infinite ...

R. D. Cess P. Mighdoll S. N. Tiwari

1967-01-01

119

Optimizing Structure of LED Light Bulb for Heat Transfer  

NASA Astrophysics Data System (ADS)

In this paper, in order to optimize the heat transfer structure of LED light bulb, the effects of various parameters on the temperature of the LED device were systematically analyzed, and a design guideline was shown. Although LED device has become popular due to its high-efficiency and long life, the design issues on the heat transfer structure of LED light bulbs has still remained. Because the original efficiency and life of the LED device can not be obtained due to the local temperature rise of LED element and the surrounding polymer molding material. Therefore, heat transfer analysis by finite element method was conducted systematically by changing parameters such as the shape, number and thickness of the radiating fin of the LED. As a result, advantage of open type structure was shown, and the proper design guidance for the structure of the fin shape was obtained.

Kobayashi, T.; Itami, D.; Hashimoto, R.; Takashina, T.; Kanematsu, H.; Mizuta, K.; Utsumi, Y.

2013-04-01

120

Motorcycle helmet ventilation and heat transfer characteristics  

Microsoft Academic Search

1. Abstract Heat transfer characteristics of 10 motorcycle helmets were measured. Each helmet was tested three times on a manikin headform placed in a climate chamber (22 C and 50% RH) at the exit of a wind tunnel (50 1.1 kmh-1). In every measurement a helmet was evaluated with the ventilation openings closed and open. Heat transfer ( Q&

C. P. Bogerd; P. A. Brhwiler

121

Natural convection heat transfer in a uniformly heated horizontal pipe  

NASA Astrophysics Data System (ADS)

Natural convection heat transfers inside horizontal pipes were measured. The Rayleigh numbers were varied from 6.8 108 to 1.5 1012, while the Prandtl number was fixed at 2,094. Based on the analogy concept, a copper sulfate electroplating system was adopted to measure mass transfer rates in place of heat transfer rates. Test results using single-piece electrodes were in good agreement with the work of Sarac and Korkut. The angle-dependent mass transfer rates, measured using piecewise electrodes, were compared with the results of studies on natural convection in concentric annuli, and showed similar trends. The experiments were expanded to the turbulent region, and a transition criterion was proposed. Angle-dependent natural convection heat transfer correlations for the laminar and turbulent regions were derived.

Chae, Myeong-Seon; Chung, Bum-Jin

2013-09-01

122

HEAT TRANSFER PROPERTIES OF SANTOWAX  

Microsoft Academic Search

Unpolymerized Santowax R (commercial name of an isomeric mixture of ; terphenyl) in the absence of radiation can be operated at bulk fluid temperature ; up to 400 deg C in contact with a heated surface at a temperature up to 520 deg C ; without any fouling of the heated surface, provided that adequate flow is ; maintained. It

R. C. Grove-Palmer; H. Pass

1959-01-01

123

Numerical study of high heat flux pool boiling heat transfer  

Microsoft Academic Search

A new numerical simulation model of boiling heat transfer is proposed based on a numerical macrolayer model [S. Maruyama, M. Shoji, S. Shimizu, A numerical simulation of transition boiling heat transfer, in: Proceedings of the Second JSMEKSME Thermal Engineering Conference, pp. 3-345-3-348, 1992]. In this model, the boiling curve is reproduced numerically by determining the macrolayer thickness. It is found

Ying He; Masahiro Shoji; Shigeo Maruyama

2001-01-01

124

Heat transfer coefficients of shell and coiled tube heat exchangers  

SciTech Connect

In the present study, the heat transfer coefficients of shell and helically coiled tube heat exchangers were investigated experimentally. Three heat exchangers with different coil pitches were selected as test section for both parallel-flow and counter-flow configurations. All the required parameters like inlet and outlet temperatures of tube-side and shell-side fluids, flow rate of fluids, etc. were measured using appropriate instruments. Totally, 75 test runs were performed from which the tube-side and shell-side heat transfer coefficients were calculated. Empirical correlations were proposed for shell-side and tube-side. The calculated heat transfer coefficients of tube-side were also compared to the existing correlations for other boundary conditions and a reasonable agreement was observed. (author)

Salimpour, M.R. [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran)

2009-01-15

125

Heat transfer behaviours of nanofluids in a uniformly heated tube  

NASA Astrophysics Data System (ADS)

In the present work, we consider the problem of the forced convection flow of water- ?Al2O3 and ethylene glycol- ?Al2O3 nanofluids inside a uniformly heated tube that is submitted to a constant and uniform heat flux at the wall. In general, it is observed that the inclusion of nanoparticles has increased considerably the heat transfer at the tube wall for both the laminar and turbulent regimes. Such improvement of heat transfer becomes more pronounced with the increase of the particle concentration. On the other hand, the presence of particles has produced adverse effects on the wall friction that also increases with the particle volume concentration. Results have also shown that the ethylene glycol- ?Al2O3 mixture gives a far better heat transfer enhancement than the water- ?Al2O3 mixture.

Maga, Sidi El Bcaye; Nguyen, Cong Tam; Galanis, Nicolas; Roy, Gilles

2004-03-01

126

Interactive Heat Transfer Simulations for Everyone  

ERIC Educational Resources Information Center

|Heat transfer is widely taught in secondary Earth science and physics. Researchers have identified many misconceptions related to heat and temperature. These misconceptions primarily stem from hunches developed in everyday life (though the confusions in terminology often worsen them). Interactive computer simulations that visualize thermal

Xie, Charles

2012-01-01

127

HEAT TRANSFER IN A PULSE COMBUSTION WATER HEATER  

Microsoft Academic Search

Pulse combustion devices offer several potential advantages over conventional burners, including enhanced efficiency, reduced size, automatic rejection of exhaust gases and consistency of operation over long time periods. This project was conducted in order to acquire an understanding of the heat transfer characteristics and pressure oscillations occurring in pulse combustion devices.^ A gas-fired pulse combustion water heater was utilized. This

HSIN-CHENG GARY HUANG; H. C. G

1984-01-01

128

Experimental investigation of heat transfer during night-time ventilation  

Microsoft Academic Search

Night-time ventilation is seen as a promising approach for energy efficient cooling of buildings. However, uncertainties in the prediction of thermal comfort restrain architects and engineers from applying this technique. One parameter essentially affecting the performance of night-time ventilation is the heat transfer at the internal room surfaces. Increased convection is expected due to high air flow rates and the

N. Artmann; R. L. Jensen; H. Manz; P. Heiselberg

2010-01-01

129

Turbulent heat transfer for pipe flow with uniform heat generation  

Microsoft Academic Search

An Analytic solution is presented of the problem of turbulent heat transfer in pipes with internal heat generation and insulated wall by applying a recently-developed eddy conductivity model. The results agree closely with available experimental data for a wide range of Prandtl number (0.0210.5).

T. Y. Na; J. P. Chiou

1979-01-01

130

Measurements of heat transfer in microchannel heat sinks  

Microsoft Academic Search

The paper presents new experimental measurements for pressure drop and heat transfer coefficient in microchannel heat sinks. Tests were performed with devices fabricated using standard Silicon 100 wafers. Two different channel patterns were studied. The parallel pattern distributed the fluid through several parallel passages between the inlet and the outlet headers located at two ends of the wafer. The series

Muhammad Mustafizur Rahman

2000-01-01

131

Periodic heat transfer through an inhomogeneous medium  

NASA Astrophysics Data System (ADS)

One dimensional heat conduction equation has been investigated for periodic heat transfer in an inhomogeneous bounded medium. Exact analytical solutions for some typical thermal conductivity profiles have been obtained. Also an approximate solution has been attempted for the first time for heat conduction problems which is applicable for any arbitrary variation of thermal conductivity. Numerical appreciation for a parabolic thermal conductivity profile shows that results from approximate approach are in excellent agreement with those obtained by the exact analytical approach.

Balla, M. Y.

1985-10-01

132

Study of heat and mass transfer in integrated thermal management controller (ITMC) employed in waste heat recovery application  

Microsoft Academic Search

In the waste heat recovery process, heat source temperature control and thermal management are always required to ensure safety and high efficiency of the waste heat recovery system. To this aim, the conventional method is to establish a series of independent heat transfer units and adopt a complex control strategy, which makes the system very complex and only applicable for

S. Li; J. Y. Wu; R. Z. Wang; Y. Huangfu

2007-01-01

133

Heat transfer in gas turbine combustors  

SciTech Connect

The present paper is concerned with the prediction of the local flow, heat-transfer, and combustion processes inside a three-dimensional can combustor chamber of a gas turbine. A three-dimensional numerical solution technique is used to solve the governing time-averaged partial differential equations and the physical modeling for turbulence, combustion, and thermal radiation. Heat-transfer modeling is emphasized in this paper. A method to calculate the distribution of temperature, radiative heat flux, and total heat flux of the liner is described. The implications of neglecting radiative heat transfer in gas turbine combustion chamber calculations are discussed. The influence of working pressure on radiative heat transfer is investigated, comparing the radiative heat flux and temperature distribution of the liner for three different working pressures: 5, 15, and 25 bar. Both radiative and convective fluxes increase with pressure, mainly because of the increase of inlet air temperature and gas emissivity. The ratio of the fluxes to the energy supplied to the combustor is very small. However, the accurate assessment of the flux distribution is an essential prerequisite for the prediction of the liner temperature distribution and liner life. 22 references.

Da Graca Carvalho, M.; Coelho, P.J.

1989-04-01

134

High efficiency advanced absorption heat pump  

Microsoft Academic Search

A high efficiency absorption heat pump for the residential market is investigated. The performance targets established for this high efficiency absorption heat pump are a heating coefficient of performance of 1.5 and a cooling coefficient of performance of 0.8 at rating conditions, including parasitic electric power consumption. The resulting heat pump would have a space heating capacity of 68,000 BTU\\/hour,

E. A. Reid Jr.

1982-01-01

135

Modeling microscale heat transfer using Calore.  

SciTech Connect

Modeling microscale heat transfer with the computational-heat-transfer code Calore is discussed. Microscale heat transfer problems differ from their macroscopic counterparts in that conductive heat transfer in both solid and gaseous materials may have important noncontinuum effects. In a solid material, three noncontinuum effects are considered: ballistic transport of phonons across a thin film, scattering of phonons from surface roughness at a gas-solid interface, and scattering of phonons from grain boundaries within the solid material. These processes are modeled for polycrystalline silicon, and the thermal-conductivity values predicted by these models are compared to experimental data. In a gaseous material, two noncontinuum effects are considered: ballistic transport of gas molecules across a thin gap and accommodation of gas molecules to solid conditions when reflecting from a solid surface. These processes are modeled for arbitrary gases by allowing the gas and solid temperatures across a gas-solid interface to differ: a finite heat transfer coefficient (contact conductance) is imposed at the gas-solid interface so that the temperature difference is proportional to the normal heat flux. In this approach, the behavior of gas in the bulk is not changed from behavior observed under macroscopic conditions. These models are implemented in Calore as user subroutines. The user subroutines reside within Sandia's Source Forge server, where they undergo version control and regression testing and are available to analysts needing these capabilities. A Calore simulation is presented that exercises these models for a heated microbeam separated from an ambient-temperature substrate by a thin gas-filled gap. Failure to use the noncontinuum heat transfer models for the solid and the gas causes the maximum temperature of the microbeam to be significantly underpredicted.

Gallis, Michail A.; Rader, Daniel John; Wong, Chung-Nin Channy; Bainbridge, Bruce L.; Torczynski, John Robert; Piekos, Edward Stanley

2005-09-01

136

Simplified models for heat transfer in rooms  

NASA Astrophysics Data System (ADS)

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

Graca, Guilherme C. C. Carrilho Da

137

Improvement of heat transfer by means of ultrasound: Application to a double-tube heat exchanger.  

PubMed

A new kind of ultrasonically-assisted heat exchanger has been designed, built and studied. It can be seen as a vibrating heat exchanger. A comprehensive description of the overall experimental set-up is provided, i.e. of the test rig and the acquisition system. Data acquisition and processing are explained step-by-step with a detailed example of graph obtained and how, from these experimental data, energy balance is calculated on the heat exchanger. It is demonstrated that ultrasound can be used efficiently as a heat transfer enhancement technique, even in such complex systems as heat exchangers. PMID:22546297

Legay, M; Simony, B; Boldo, P; Gondrexon, N; Le Person, S; Bontemps, A

2012-04-11

138

Heat transfer studies. Quarterly report  

SciTech Connect

Nitrogen gas has been replaced by room air in the extension of multi-phase models to sub-residual saturation experiments on drying. The TOUGH2 code has been used to simulate the same problem with the identical boundary conditions. A constant heat flux boundary condition on the heater has been performed in the repository drift experiment. The desired constant heat flux can produce a steady-state heater temperature ({approx}238{degrees}C) close to the constant heater surface temperature used before. What occurs in the air annulus and in the porous medium with the different thermal boundary conditions and water quantities is reported.

Boehm, R.; Chen, Y.T.; Ma, L.

1995-04-20

139

Optimal paths for minimizing entropy generation during heat transfer processes with a generalized heat transfer law  

NASA Astrophysics Data System (ADS)

An investigation of finite-time heat transfer processes between high- and low-temperature sides with a generalized heat transfer law (q~[?(Tn)]m) is presented in this paper. Optimal heating and cooling strategies for minimizing entropy generation are derived for the fixed initial and final temperatures of the low-temperature side working fluid. Optimal paths are compared with the common strategies of constant heat flux and constant source temperature operation by numerical examples. The condition corresponding to the minimum entropy generation strategy is not only valid for Newton's [q~(?T)] and linear phenomenological [q~?(T-1)] heat transfer laws but also valid for heat transfer law (q~[?(T-1)]m). The obtained results are general and can provide some theoretical guidelines for the designs and operations of practical heat exchangers.

Chen, Lingen; Xia, Shaojun; Sun, Fengrui

2009-02-01

140

Radiative heat transfer in two-phase media  

NASA Astrophysics Data System (ADS)

Physical processes occurring in radiating two-phase media are examined with emphasis on radiative heat transfer in the combustion chambers of thermal power plants. In particular, correct effective temperatures are determined for radiating and dissipating media with reflecting and radiating boundary surfaces; radiation characteristics and thermal efficiencies of the surfaces are calculated. An approximate method is developed for taking account of multiple scattering processes in a plane two-phase layer bounded by surfaces with specified optical properties. Based on approximate expressions for blackness, computer programs are developed for engineering calculations of radiative heat transfer in combustion chambers.

Adzerikho, Kazimir Serafimovich; Nogotov, Evgenii Fomich; Trofimov, Vladimir Petrovich

141

Heat-transfer studies in circulating fluidized beds  

SciTech Connect

Circulating fluidized bed combustors (CFBC) employing fine limestone offer many potential advantages over the design approach using a shallow bed of coarse limestone, which has dominated efforts to date. Potential advantages include higher combustion efficiencies, reduced limestone needs, simpler fuel and limestone feed system, elimination of unacceptable heat transfer surface erosion, and better turn-down and response rate. These studies investigated the heat transfer in circulating fluidized beds with externally-heated (bed-to-wall) and internally-heated (bed-to-suspended vertical surface) flow. The fluidized particles used were sands (300, 500 {mu}m) and glass beads (600 {mu}m) respectively. The measurement covered a range of superficial gas velocities 4-17 m/sec, suspension densities from 3-140 kg/m{sup 3} and suspension temperature from 40-350 C. The heat transfer coefficients depend strongly on suspension density, but show almost no dependence on gas velocities and bed temperature. A model which predicts the observed relation of heat transfer coefficient to solid thermal properties is based on particle heat absorption. The residence time was assumed to be the same for all particles and calculated to be the time for a particle to fall the length of the jacket. Particles were assumed to move at the terminal velocity along the wall. The results were in good agreement with the prediction of this model.

Sekthira, A.

1988-01-01

142

Heat transfer in a thermoacoustic process  

NASA Astrophysics Data System (ADS)

Thermoacoustic instability is defined as the excitation of acoustic modes in chambers with heat sources due to the coupling between acoustic perturbations and unsteady heat addition. The major objective of this paper is to achieve accurate theoretical results in a thermoacoustic heat transfer process. We carry out a detailed heat transfer analysis aimed at determining the stability-instability border of the thermoacoustic system. In this paper, we present a project type of physical examination and modelling task. We employed an electrically heated Rijke tube in our thermoacoustic project work. The aim of our project is to help our students enlarge their knowledge about thermodynamics, mainly about thermoacoustics, and develop their applied information technology and mathematical skills.

Beke, Tamas

2012-11-01

143

Numerical methods in heat transfer  

Microsoft Academic Search

Topics discussed in this book include modelling the effects of fire, ablation, heat flow in porous rock, thermal stress and dissolving coal. Alternative energy sources such as geothermal reservoirs and solar radiation are also discussed. Includes bibliographies at the end of the papers, a cited author index, and a subject index. Contents, abridged: Exact finite element solutions for linear steady

R. W. Lewis; K. Morgan; B. A. Schrefler

1983-01-01

144

Gas-side heat transfer with rotation  

NASA Astrophysics Data System (ADS)

The primary basis for heat transfer analysis of turbine blades is experimental data obtained in linear cascades. These data have been very valuable in identifying the major heat transfer and fluid flow features of a turbine airfoil. The question of major interest is how well all of these data translate to the rotating turbine blade. It is known from the work of Lokay and Trushin that average heat transfer coefficients on the rotor may be as much as 40 percent above the values measured on the same blades nonrotating. Recent work by Dunn and Holt supports the Russian conclusion. What is lacking is a set of data from a rotating system which is of sufficient detail as to make careful local comparisons between static system in which there is sufficient documentation of the flow field to support the computer analyses being developed today. A second major question is the influence, if any, of the first stator row on the heat transfer of the second stator row after the flow has passed through the rotor. An objective of the present program, is to obtain a detailed set of heat transfer coefficients along the midspan of a blade in a rotating turbine.

Dring, R. P.

1983-10-01

145

Dissociation heat transfer characteristics of methane hydrates  

SciTech Connect

Knowledge of the interfacial heat transfer phenomenon during the dissociation of gas hydrates is essential in modeling the hydrate dissociation process. Such knowledge has applications in natural gas processing, storage, or transportation; in the drilling and recovery of oil and gas in the presence of gas hydrates; in the desalination of sea water; and in the production of natural gas from hydrate reservoirs. The process of hydrate dissociation is a unique phenomenon in which gas and water are simultaneously produced at the dissociated hydrate surface and play an important role in the mechanism of heat transfer to hydrates. An earlier study of propane hydrate dissociation showed that hydrate dissociation is a heat-transfer-limited process and somewhat similar to the nucleate boiling of liquids. In the present study, heat transfer limitations for methane hydrate dissociation were studied for two reasons. First, a comparison of the results of this study with propane hydrate was desired. Second, the effect of hydrate structure and gas molecule type on the rate of heat transfer during hydrate dissociation was sought.

Kamath, V.A.; Holder, G.D.

1987-02-01

146

Characteristics of Transient Boiling Heat Transfer  

SciTech Connect

In this paper, one dimensional inverse heat conduction solution is used for a measurement of pool boiling curve. The experiments are performed under atmospheric pressure for copper, brass, carbon steel and gold. Boiling curves, including unsteady transition boiling region, are found can be traced fairly well from a simple experiment system by solving inverse heat conduction solution. Boiling curves for steady heating and transient heating, for heating process and cooling process are compared. Surface behavior around CHF point, transition boiling and film-boiling regions are observed by using a high-speed camera. The results show the practicability of the inverse heat conduction solution in tracing boiling curve and thereby supply us a new way in boiling heat transfer research. (authors)

Liu, Wei; Monde, Masanori; Mitsutake, Y. [Saga University, 1 Honjo Saga City, Saga 840-8502 (Japan)

2002-07-01

147

Turbulent Convection Heat Transfer in Longitudinally Conducting, Externally Finned Pipes  

Microsoft Academic Search

A numerical investigation is conducted of turbulent convection in a longitudinally conducting, externally finned pipe. Results reveal significant enhancement in heat transfer due to finning. The heat transfer rate to the fluid increases with increasing thermal conductivity of the pipe wall, with increasing values of the external heat transfer coefficient, and with decreasing interfin spacing. Heat transfer is underestimated by

F. Moukalled; J. Kasamani; S. Acharya

1992-01-01

148

Evaluation of heat transfer coefficient during heat treatment by inverse analysis  

Microsoft Academic Search

Reliable prediction of the properties of a heat-treated workpiece requires accurate data of the heat transfer coefficient during heat treatment process. In the present investigation, inverse heat transfer formulation using a two-dimensional finite element method was developed as a tool to evaluate heat transfer coefficient during heat treatment. The formulation has a function of providing a time profile of heat

H. K. Kim; S. I. Oh

2001-01-01

149

An Exploration of Viral Transfer Efficiency Factors  

NASA Astrophysics Data System (ADS)

Viruses exist on common household surfaces and persist on them (Abad 1994, Rusin 2002). In addition to this, they are able to transfer from surface to surface, and when in contact with humans, can cause illness. In a previous study, we were able to test out the transfer efficiencies of three different phages. Transfer efficiency is defined as follows: Transfer Efficiency: Phage recovered from surface 2 / (Phage recovered from surface 2 + Phage recovered from surface 1) The phages tested have similar size and shape, but vary in isoelectric points and route of infection (Maier 2000). Preliminary studies have suggested that the transfer efficiencies for each phage may be different. Because of this, we are investigating what is the cause of this difference in phage transfer. Two possibilities for these differences are the phage's properties and the cotton tip swab elution from each surface. Using the statistical method known as the student t-test and the experimental methods for phage elution and a double agar overlay phage enumeration, we examined whether the cotton tip swab elution was responsible for phage transfer differences.

Tamayo, F. J.; Julian, T.; Boehm, A.

2008-12-01

150

Solar heat transfer and storage system  

SciTech Connect

This patent describes a heat transfer and storage system comprising: (a) a heat storage chamber having a phase change material contained therein; (b) water heater means for containing potable water, and including first conduit means through which the water flows, the first conduit means having a portion thereof extending through the phase change material in the chamber; (c) means for collecting heat energy, and including second conduit means through which a heat transfer liquid flows. The second conduit has a portion thereof extending through the phase change material in the chamber in adjacent parallel relation to the portion of the first conduit means; (d) fin means extending outwardly from the portion of the first and second conduit means to transfer heat between the conduit portions and the phase change material; and (e) connecting means simultaneously holding the portions of the first and second conduit means in adjacent heat conducting relationship to one another and holding the fin means interposed between the portions of the first and second conduit means in a heat conducting relationship therewith.

McCall, D.

1986-11-25

151

Measurement techniques in heat and mass transfer  

NASA Astrophysics Data System (ADS)

Papers are presented on optical measurement methods, developments in heat and mass transfer measurement, and power engineering measurements. Consideration is given to laser beam techniques for measuring two-phase boundary motion in boiling, the use of flow visualization and thermometric probes for studies of turbulent transfer in a viscous sublayer, natural convection, and an investigation on the performance of transonic turbine blade cascade for varying incidence angles. Topics discussed include the measurement of thermal and hydraulic parameters, emission of thermal radiation from solids and fluids, reactor safety measurement techniques, and probes for local velocity and turbulent heat flux measurement in liquid metals.

Soloukhin, R. I.; Afgan, N. H.

152

Microscale surface modifications for heat transfer enhancement.  

PubMed

In this experimental study, two surface modification techniques were investigated for their effect on heat transfer enhancement. One of the methods employed the particle (grit) blasting to create microscale indentations, while the other used plasma spray coating to create microscale protrusions on Al 6061 (aluminum alloy 6061) samples. The test surfaces were characterized using scanning electron microscopy (SEM) and confocal scanning laser microscopy. Because of the surface modifications, the actual surface area was increased up to 2.8 compared to the projected base area, and the arithmetic mean roughness value (Ra) was determined to vary from 0.3 ?m for the reference smooth surface to 19.5 ?m for the modified surfaces. Selected samples with modified surfaces along with the reference smooth surface were then evaluated for their heat transfer performance in spray cooling tests. The cooling system had vapor-atomizing nozzles and used anhydrous ammonia as the coolant in order to achieve heat fluxes up to 500 W/cm(2) representing a thermal management setting for high power systems. Experimental results showed that the microscale surface modifications enhanced heat transfer coefficients up to 76% at 500 W/cm(2) compared to the smooth surface and demonstrated the benefits of these practical surface modification techniques to enhance two-phase heat transfer process. PMID:24003985

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

2013-09-19

153

Inner heat source model with heat and moisture transfer in soil around the underground heat exchanger  

Microsoft Academic Search

This paper presents an inner heat source model of underground heat exchanger based on the heat and mass transfer theory in soil. A number of factors such as moisture movement in soil, soil type, and soil property were taken into account in the model. The underground heat exchanger was simplified as the equivalent inner heat source term in the model.

Xinguo Li; Jun Zhao; Qian Zhou

2005-01-01

154

Heat transfer on a microcylinder with slip  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to determine the heat transfer from a semi-infinite microcylinder under uniform axial flow in the slip regime. Following the treatments of Glauert and Lighthill (Proc Royal Soc 230A:188-203, 1955), and Crane (Ingenieur-Archiv 43:203-214, 1974), an asymptotic series solution is developed to account for the heat flux in terms of the Nusselt number for large axial distances along a cylinder maintained at constant temperature.

Crane, L. J.; McVeigh, A. G.

2010-12-01

155

Development of cryogenic rotatable heat transfer joints  

Microsoft Academic Search

A summary of cryogenic rotatable heat transfer joint technology development, at Rockwell International Space Division, is presented. Starting with the flight qualified radiative joint on the RM-20B IR sensor of the early 70's, leading to rotatable heat pipe joint, gas conductive joints, rolling-contact-conductance joints, and the more recent work on development and evaluation of cryogenic rotatable seals and mechanical interfaces.

J. A. Sadunas; Z. F. Backovsky; D. E. Wilson

1992-01-01

156

Heat transfer from a heated tube in shallow vibrated beds  

SciTech Connect

The objective of this study was to develop the experimental systems and measurement methods to permit an accurate measurement of surface-to-bed heat transfer in vibrated beds (i.e., beds of solids that are levitated or ''fluidized'' by external vibrations alone) and to obtain a better understanding of the mechanisms of vibrated-bed heat transfer. Specifically, a fully-instrumented vibrated-bed system equipped with a computerized heat probe capable of maintaining an essentially constant surface temperature has been successfully designed, constructed and tested. The system was used to quantitatively investigate the effects of key operating variables, such as vibrational intensity and particle size, on the surface-to-bed heat transfer. In addition, through the use of video recording, strobe lighting, colored tracer particles, phase-shifted photography and instantaneous floor-pressure measurements, significant new insights were obtained on the bed structures, solid circulation patterns and air gap formations along with their effects on surface-to-bed heat transfer.

Thomas, B.; Sprung, R.; Liu, Y.A.; Squires, A.M.

1986-01-01

157

Self supporting heat transfer element  

DOEpatents

The present invention provides an improved internal heat exchange element arranged so as to traverse the inside diameter of a container vessel such that it makes good mechanical contact with the interior wall of that vessel. The mechanical element is fabricated from a material having a coefficient of thermal conductivity above about 0.8 W cm.sup.-1.degree. K.sup.-1 and is designed to function as a simple spring member when that member has been cooled to reduce its diameter to just below that of a cylindrical container or vessel into which it is placed and then allowed to warm to room temperature. A particularly important application of this invention is directed to a providing a simple compartmented storage container for accommodating a hydrogen absorbing alloy.

Story, Grosvenor Cook (Livermore, CA); Baldonado, Ray Orico (Livermore, CA)

2002-01-01

158

Heat transfer analysis of boreholes in vertical ground heat exchangers  

Microsoft Academic Search

A ground heat exchanger (GHE) is devised for extraction or injection of thermal energy from\\/into the ground. Bearing strong impact on GHE performance, the borehole thermal resistance is defined by the thermal properties of the construction materials and the arrangement of flow channels of the GHEs. Taking the fluid axial convective heat transfer and thermal short-circuiting among U-tube legs into

Heyi Zeng; Nairen Diao; Zhaohong Fang

2003-01-01

159

Cooperative heat transfer and ground coupled storage system  

DOEpatents

A cooperative heat transfer and ground coupled storage system wherein collected solar heat energy is ground stored and permitted to radiate into the adjacent ground for storage therein over an extended period of time when such heat energy is seasonally maximally available. Thereafter, when said heat energy is seasonally minimally available and has propagated through the adjacent ground a substantial distance, the stored heat energy may be retrieved by a circumferentially arranged heat transfer means having a high rate of heat transfer.

Metz, Philip D. (Rocky Point, NY)

1982-01-01

160

ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS: Highly Efficient Lattice Boltzmann Model for Compressible Fluids: Two-Dimensional Case  

NASA Astrophysics Data System (ADS)

We present a highly efficient lattice Boltzmann model for simulating compressible flows. This model is based on the combination of an appropriate finite difference scheme, a 16-discrete-velocity model [Kataoka and Tsutahara, Phys. Rev. E 69 (2004) 035701(R)] and reasonable dispersion and dissipation terms. The dispersion term effectively reduces the oscillation at the discontinuity and enhances numerical precision. The dissipation term makes the new model more easily meet with the von Neumann stability condition. This model works for both high-speed and low-speed flows with arbitrary specific-heat-ratio. With the new model simulation results for the well-known benchmark problems get a high accuracy compared with the analytic or experimental ones. The used benchmark tests include (i) Shock tubes such as the Sod, Lax, Sjogreen, Colella explosion wave, and collision of two strong shocks, (ii) Regular and Mach shock reflections, and (iii) Shock wave reaction on cylindrical bubble problems. With a more realistic equation of state or free-energy functional, the new model has the potential tostudy the complex procedure of shock wave reaction on porous materials.

Chen, Feng; Xu, Ai-Guo; Zhang, Guang-Cai; Gan, Yan-Biao; Cheng, Tao; Li, Ying-Jun

2009-10-01

161

Microscale Heat Transfer Transduced by Surface Plasmon Resonant Gold Nanoparticles  

PubMed Central

Visible radiation at resonant frequencies is transduced to thermal energy by surface plasmons on gold nanoparticles. Temperature in ?10-microliter aqueous suspensions of 20-nanometer gold particles irradiated by a continuous wave Ar+ ion laser at 514 nm increased to a maximum equilibrium value. This value increased in proportion to incident laser power and in proportion to nanoparticle content at low concentration. Heat input to the system by nanoparticle transduction of resonant irradiation equaled heat flux outward by conduction and radiation at thermal equilibrium. The efficiency of transducing incident resonant light to heat by microvolume suspensions of gold nanoparticles was determined by applying an energy balance to obtain a microscale heat-transfer time constant from the transient temperature profile. Measured values of transduction efficiency were increased from 3.4% to 9.9% by modulating the incident continuous wave irradiation.

Roper, D. Keith; Ahn, W.; Hoepfner, M.

2008-01-01

162

Numerical comparison of radiative heat transfer models  

Microsoft Academic Search

A numerical comparison is presented for two mathematical models of radiative heat transfer, a direct method using the Stefan-Boltzmann law and a two step method using flux models (called the radiosity approach). The flux model equations are solved by the successive approximation technique and Hottel's matrix inversion technique, and a rectangular parallelopiped is assumed for the enclosure in order to

S. Vaidyanathan; M. Achuthan; A. Jaganmohan

1982-01-01

163

Heat and mass transfer in porous media  

SciTech Connect

Field test data on the OOSI MR3 experiments are used as a basis for exhibiting the computational capabilities of the WAFE computer code, which is a generalized tool for the analysis of heat and mass transfer in multi-dimensional domains of porous geothermal materials.

Cook, T.L.; Harlow, F.H.; Travis, B.J.; Bartel, T.J.; Tyner, C.E.

1981-01-01

164

Heat transfer and fluid flow in microchannels  

Microsoft Academic Search

Fluid flow and heat transfer characteristics in microchannels of different cross-sections; parallel plate, cylindrical and trapezoidal microchannels were studied. The trapezoidal microchannels were etched in silicon and glass by photolithographic techniques. The cylindrical microchannels of fused silica and stainless steel were readily available. Channels with depths of 18 mum to 300 mum were studied. The study was divided into three

Ghulam Mohiuddin Mala

1999-01-01

165

Heat and mass transfer in multicylinder drying  

Microsoft Academic Search

A mathematical model describing the heat and mass transfer in the dryer section of a paper machine has been applied to the production data from four paper machines. Model predictions for the machine speed are compared to actual machine speeds for a total of 163 data sets. The mathematical model assumes that the temperature and moisture content remain homogeneous in

Lars Nilsson

2004-01-01

166

Mechanism of heat transfer in vacuum superinsulation  

Microsoft Academic Search

This paper shows that the experimentally observed point of inflection on the temperature curve in vacuum superinsulatlon is due to the nonuniform residual gas pressure in the layers and the significant contribution of the gas conductivity to the total heat transfer.

R. S. Mikhal'Chenko; V. F. Get'manets; B. Ya. Sukharevskii

1970-01-01

167

Heat transfer measurements with ice slurry.  

National Technical Information Service (NTIS)

In order not to increase energy consumption by introducing a secondary refrigerant, the use of ice slurry may be very interesting. Heat transfer coefficient and pressure drop for ice slurry flowing in a horizontal pipe have been measured. The stainless st...

K. G. Christensen M. Kauffeld

1997-01-01

168

Forced Convection Heat Transfer in Circular Pipes  

ERIC Educational Resources Information Center

|One of the pitfalls of engineering education is to lose the physical insight of the problem while tackling the mathematical part. Forced convection heat transfer (the Graetz-Nusselt problem) certainly falls into this category. The equation of energy together with the equation of motion leads to a partial differential equation subject to various

Tosun, Ismail

2007-01-01

169

Dissociation heat transfer characteristics of methane hydrates  

Microsoft Academic Search

Knowledge of the interfacial heat transfer phenomenon during the dissociation of gas hydrates is essential in modeling the hydrate dissociation process. Such knowledge has applications in natural gas processing, storage, or transportation; in the drilling and recovery of oil and gas in the presence of gas hydrates; in the desalination of sea water; and in the production of natural gas

V. A. Kamath; G. D. Holder

1987-01-01

170

Heat Transfer Fluid Experiences at the MSSTF.  

National Technical Information Service (NTIS)

Samples of the heat transfer fluid (mixture of Therminol 66 and Caloria HT43) have been taken periodically from the DOE/Sandia Midtemperature Solar Systems Test Facility for the purpose of determining whether there is any long-term degradation as evidence...

W. H. McCulloch

1980-01-01

171

Infrared Radiative Heat Transfer in Nongray Gases.  

National Technical Information Service (NTIS)

The object of the investigation was to study various approximate methods of analyzing infrared radiative heat transfer in nongray nonisothermal gases. For this purpose, a very simple physical system was chosen, and this consists of a gas bounded by two in...

R. D. Cess P. Mighdoll S. N. Tiwari

1967-01-01

172

Suppression of the sonic heat transfer limit in high-temperature heat pipes  

Microsoft Academic Search

The design of high-performance heat pipes requires optimization of heat transfer surfaces and liquid and vapor flow channels to suppress the heat transfer operating limits. In the paper an analytical model of the vapor flow in high-temperature heat pipes is presented, showing that the axial heat transport capacity limited by the sonic heat transfer limit depends on the working fluid,

Flavio Dobran

1989-01-01

173

Analysis of natural convective heat transfer of nano coated aluminium fins using Taguchi method  

NASA Astrophysics Data System (ADS)

Rectangular aluminium fins were preferred for analysis and coated by carbon nano tubes using PVD to enhance the heat transfer rate of fins. Convective heat transfer rates for coated and non-coated surfaces were calculated and compared. The temperature and heat transfer characteristics were investigated using Nusselt, Grashof, Prandtl and Rayleigh numbers and also optimized by Taguchi method and ANOVA analysis. The average percentage of increase in fin efficiency is 5 %.

Senthilkumar, R.; Nandhakumar, A. J. D.; Prabhu, S.

2013-01-01

174

Thermodynamic simulation of performance of an Otto cycle with heat transfer and variable specific heats of working fluid  

Microsoft Academic Search

The performance of an air-standard Otto cycle with heat transfer loss and variable specific heats of working fluid is analyzed by using finite-time thermodynamics. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between power output and the efficiency of the cycle are derived by

Yanlin Ge; Lingen Chen; Fengrui Sun; Chih Wu

2005-01-01

175

Heat transfer study of a heat storage container with a phase change material. (Part 2. Heat transfer in the melting process in a cylindrical heat storage container)  

Microsoft Academic Search

Calcium chloride hexahydrate as a latent-heat storage material is placed in a vertical cylindrical heat storage container, and a vertical single pipe for heat transfer purpose is also inserted in the container. In this setup, the heat transfer rates during melting of the heat storage material is largely influenced by natural convection at the melting liquid layer section. Also, regarding

Michio Yanadori; Takashi Masuda

1989-01-01

176

Sizing up heat transfer fluids and heaters  

SciTech Connect

While steam is commonly used in the chemical process industries (CPI) because of its low cost and easy accessibility, it is not always a suitable source of heat. For example, steam systems operating at high temperatures require extremely high pressures, making the use of steam impractical. Heat transfer fluids in combination with fired heaters, on the other hand, can handle the high temperatures without having to deal with the high pressures. Petroleum-derived heat transfer fluids are limited to bulk operating temperatures of about 600 F. For temperatures up to 750 F, synthetic organic fluids are commonly used. Silicone-based fluids, which are less susceptible to fouling than synthetic organic fluids, are also an option for systems that need to be heated to 750 F. They may have use in applications where both high-operating temperature and pumpability at low temperatures are required. However, silicone-based fluids are typically more expensive than other heat transfer fluids. This article covers the selection of synthetic organic fluids operating at temperatures above 600 F. Design and selection of liquid tube-type fired heaters are also discussed.

Guffey, G.E. II [Eastman Chemical Co., Kingsport, TN (United States)

1997-10-01

177

Combined heat and mass transfer device for improving separation process  

DOEpatents

A two-phase small channel heat exchange matrix simultaneously provides for heat transfer and mass transfer between the liquid and vapor phases of a multi-component mixture at a single, predetermined location within a separation column, significantly improving the thermodynamic efficiency of the separation process. The small channel heat exchange matrix is composed of a series of channels having a hydraulic diameter no greater than 5.0 millimeters for conducting a two-phase coolant. In operation, the matrix provides the liquid-vapor contacting surfaces within the separation column, such that heat and mass are transferred simultaneously between the liquid and vapor phases. The two-phase coolant allows for a uniform heat transfer coefficient to be maintained along the length of the channels and across the surface of the matrix. Preferably, a perforated, concave sheet connects each channel to an adjacent channel to facilitate the flow of the liquid and vapor phases within the column and to increase the liquid-vapor contacting surface area. 12 figs.

Tran, T.N.

1999-08-24

178

Combined heat and mass transfer device for improving separation process  

DOEpatents

A two-phase small channel heat exchange matrix simultaneously provides for heat transfer and mass transfer between the liquid and vapor phases of a multi-component mixture at a single, predetermined location within a separation column, significantly improving the thermodynamic efficiency of the separation process. The small channel heat exchange matrix is composed of a series of channels having a hydraulic diameter no greater than 5.0 millimeters for conducting a two-phase coolant. In operation, the matrix provides the liquid-vapor contacting surfaces within the separation column, such that heat and mass are transferred simultaneously between the liquid and vapor phases. The two-phase coolant allows for a uniform heat transfer coefficient to be maintained along the length of the channels and across the surface of the matrix. Preferably, a perforated, concave sheet connects each channel to an adjacent channel to facilitate the flow of the liquid and vapor phases within the column and to increase the liquid-vapor contacting surface area.

Tran, Thanh Nhon (Flossmoor, IL)

1999-01-01

179

Advanced Heat Transfer and Thermal Storage Fluids  

SciTech Connect

The design of the next generation solar parabolic trough systems for power production will require the development of new thermal energy storage options with improved economics or operational characteristics. Current heat-transfer fluids such as VP-1?, which consists of a eutectic mixture of biphenyl and diphenyl oxide, allow a maximum operating temperature of ca. 300 C, a limit above which the vapor pressure would become too high and would require pressure-rated tanks. The use of VP-1? also suffers from a freezing point around 13 C that requires heating during cold periods. One of the goals for future trough systems is the use of heat-transfer fluids that can act as thermal storage media and that allow operating temperatures around 425 C combined with lower limits around 0 C. This paper presents an outline of our latest approach toward the development of such thermal storage fluids.

Moens, L.; Blake, D.

2005-01-01

180

A review of empirical flame impingement heat transfer correlations  

Microsoft Academic Search

Impinging flames are used in industrial heating and melting, safety research, and aerospace applications. Multiple modes of heat transfer are commonly important in those processes. However, the detailed heat transfer mechanisms are not well understood. The available semianalytical heat transfer solutions have only limited applicability. Therefore, researchers and designers have either made measurements or used empirical correlations to determine the

C. E. Baukal; B. Gebhart

1996-01-01

181

A small scale multi-effect distillation (MED) unit for rural micro enterprises: Part-III Heat transfer aspects  

Microsoft Academic Search

Overall Heat Transfer Co-efficient (OHTC) is the governing factor for heat transfer and depends on surface area utilized for heat transfer and temperature difference. The aspects of fabrication, design and operation along with design optimization of various components of the small scale multiple effect distillation (MED) unit have been discussed in part I and part II of the paper. As

P. K. Sen; Padma Vasudevan Sen; Anurag Mudgal; S. N. Singh

2011-01-01

182

Analysis of combined conductive and radiative heat transfer in a two-dimensional rectangular enclosure using the discrete ordinates method  

Microsoft Academic Search

An efficient tool to deal with multidimensional radiative heat transfer is in strong demand to analyze the various thermal problems combined either with other modes of heat transfer or with combustion phenomena. The current study examines the discrete ordinates method (DOM) for coupled radiative and conductive heat transfer in rectangular enclosures in which either a nonscattering or scattering medium is

Taik Young Kim; Seung Wook Baek

1991-01-01

183

Heat transfer between graphene and amorphous SiO2.  

PubMed

We study the heat transfer between graphene and amorphous SiO(2). We include both the heat transfer from the area of real contact, and between the surfaces in the non-contact region. We consider the radiative heat transfer associated with the evanescent electromagnetic waves which exist outside of all bodies, and the heat transfer by the gas in the non-contact region. We find that the dominant contribution to the heat transfer results from the area of real contact, and the calculated value of the heat transfer coefficient is in good agreement with the value deduced from experimental data. PMID:21403360

Persson, B N J; Ueba, H

2010-10-29

184

Heat-transfer performance of a corrugated-tube thermosiphon. Part 1; Evaporator performance  

Microsoft Academic Search

Two-phase closed thermosiphons are highly efficient heat-transfer elements with applications in terrestrial heat-transport and heat-recovery systems. In this paper, a corrugated copper tube was used as the container of the thermosiphons and distilled water was used as the working fluid. The influences of the liquid charge ratio and inclination angle on the heat-transfer performance were studied. It was found that

K. Negishi; K. Kaneko; T. Matsuoka; M. Hirashima; Y. Nishikawa; M. Taguchi

1991-01-01

185

Analysis of Influencing Factors of Heat Transfer Performance of Heat Pipe Heat Exchanger  

Microsoft Academic Search

Heat transfer performance of heat pipe heat exchanger affected by many factors, such as the opening temperature of the heat pipe, the rate of fluid-filled, the physical nature of liquid refrigerant, the work temperature of tube, angle, tube spacing, tube length, hot and cold fluid flow and wind speed. The above-mentioned parameters can not be measured because of Test conditions,

Zhang Jie; Ren Yan; Zhang Lihong; Liang Huimin

2009-01-01

186

Heat transfer and pressure drop of spined pipe in cross flow. Part 2; Heat transfer studies  

Microsoft Academic Search

Hot water at a temperature of about 120 ° F (49° C) circulated through a single row of aluminum (type 2024) spined pipe and transferred heat to room-temperature air in cross flow. Heat transfer was measured by performing an energy balance on the flowing water. Two sizes of spined pipe were studied, each at three different spacings. The 1\\/4 in.

M. T. Holtzapple; K. Lin; A. L. Allen

1990-01-01

187

Heat and mass transfer modeling in air drying of foods  

Microsoft Academic Search

Heat and mass transfer modeling in the air drying of solids is considered as a two stage procedure. The former aims to discover the dominant heat and mass transfer phenomena (heat versus mass, internal versus external), the latter aims to formulate empirical equations for the calculation of the corresponding heat and mass transport properties (mass diffusivity, thermal conductivity, boundary heat

Z. B. Maroulis; C. T. Kiranoudis; D. Marinos-Kouris

1995-01-01

188

Comparison of performances of air standard Atkinson and Otto cycles with heat transfer considerations  

Microsoft Academic Search

In this paper, the effects of heat transfer on the net output work and the indicated thermal efficiency of an air standard Atkinson cycle are analyzed. Comparisons of the performances of air standard Atkinson and Otto cycles with heat transfer considerations are also discussed. We assume that the compression and power processes are adiabatic and reversible and that any convective,

Shuhn-Shyurng Hou

2007-01-01

189

Heat transfer enhancement and performance of the molten salt receiver of a solar power tower  

Microsoft Academic Search

This paper investigates the interaction between the heat transfer performance and the thermal efficiency of a molten salt receiver used in the solar power tower plant. A test-bed is built, and a series of experiments of heat transfer enhancement for two types of molten salt receiver tubes, including smooth and spiral tubes, have been carried out under the high temperature

Minlin Yang; Xiaoxi Yang; Xiaoping Yang; Jing Ding

2010-01-01

190

Mass transfer in oscillating flows: Efficient drying via pulse combustors  

NASA Astrophysics Data System (ADS)

Analytical and experimental methods are addressed for increasing industrial and home drying efficiency via pulse combustors. A fundamental scientific methodology is being developed for the momentum, heat, and mass transfer in oscillating (on the mean) turbulent flows. The approach follows the intuitive ideas of Taylor and Kolmogorov on the construction of microscales of turbulence. A parallel experimental program was carried out by the pulse combustor of the Continuous Combustion Lab of Sandia-Livermore National Labs. A droplet sizing technique and a quasi-steady computer model were developed. The unsteady analytical model determines the range of the quasi-steady model and provides also a mass transfer correlation beyond this range. The scales of mass transfer in oscillating turbulent flows were developed. A mass transfer correlation based on these scales was proposed. The correlation agrees well with the results so far obtained in the experimental program.

Arpaci, V. S.; Gemmen, R.; Selamet, A.

1990-04-01

191

Radiative heat transfer in plastic welding process  

NASA Astrophysics Data System (ADS)

This paper deals with a novel CO2 laser plastic welding procedure developed from the point of view of heat transfer containing simultaneous radiation and conduction processes and also gives a brief review of plastic welding development to date. The principle and features are shown by both the experiments using CO2 laser as a radiation source and numerical simulation considering heat transfer phenomena in simultaneous radiation and conduction in welding process. The feasibility of the proposed procedure is confirmed by applying the overlapped same plastic films with combination of infrared radiation absorbing heating and thermal diffusion cooling processes. A solid material transparent to infrared radiation with a high thermal diffusivity is used as a heat sink in contact with the irradiated surface of overlapped thermoplastics during radiation heating. The procedure is able to achieve both high welding strength and excellent surface appearance without causing surface thermal damage as often suffered in conventional direct infrared radiation welding process. In addition, pigmentation in welding material to increase absorption of radiation is unnecessary for this method.

Kurosaki, Yasuo

2005-06-01

192

Maximal near-field radiative heat transfer between two plates  

NASA Astrophysics Data System (ADS)

Near-field radiative transfer is a promising way to significantly and simultaneously enhance both thermo-photovoltaic (TPV) devices power densities and efficiencies. A parametric study of Drude and Lorentz models performances in maximizing near-field radiative heat transfer between two semi-infinite planes separated by nanometric distances at room temperature is presented in this paper. Optimal parameters of these models that provide optical properties maximizing the radiative heat flux are reported and compared to real materials usually considered in similar studies, silicon carbide and heavily doped silicon in this case. Results are obtained by exact and approximate (in the extreme near-field regime and the electrostatic limit hypothesis) calculations. The two methods are compared in terms of accuracy and CPU resources consumption. Their differences are explained according to a mesoscopic description of nearfield radiative heat transfer. Finally, the frequently assumed hypothesis which states a maximal radiative heat transfer when the two semi-infinite planes are of identical materials is numerically confirmed. Its subsequent practical constraints are then discussed. Presented results enlighten relevant paths to follow in order to choose or design materials maximizing nano-TPV devices performances.

Nefzaoui, Elyes; Ezzahri, Youns; Drvillon, Jrmie; Joulain, Karl

2013-09-01

193

Laminar Heat Transfer in a Pipe Subjected to a Circumferentially Varying External Heat Transfer Coefficient  

Microsoft Academic Search

Numerical techniques have been used to solve the thermally developed regime for a laminar pipe flow that exchanges heat with a fluid environment in the presence of a circumferentiatly varying external heat transfer coefficient. By making use of the fact that the temperature distributions have similar shapes at successive streamwise locations, the three-dimensional temperature field was scaled to two dimensions.

E. M. Sparrow; S. V. Patankar; H. Shahrestani

1978-01-01

194

Laminar heat transfer in a pipe subjected to a circumferentially varying external heat transfer coefficient  

Microsoft Academic Search

Numerical techniques have been used to solve the thermally developed regime for a laminar pipe flow that exchanges heat with a fluid environment in the presence of a circumferentially varying external heat transfer coefficient. By making use of the fact that the temperature distributions have similar shapes at successive streamwise locations, the three-dimensional temperature field was scaled to two dimensions.

E. M. Sparrow; S. V. Patankar; H. Shahrestani

1978-01-01

195

Acquisition systems for heat transfer measurement  

SciTech Connect

Practical heat transfer data acquisition systems are normally characterized by the need for high-resolution, low-drift, low-speed recording devices. Analog devices such as strip chart or circular recorders and FM analog magnetic tape have excellent resolution and work well when data will be presented in temperature versus time format only and need not be processed further. Digital systems are more complex and require an understanding of the following components: digitizing devices, interface bus types, processor requirements, and software design. This paper discusses all the above components of analog and digital data acquisition, as they are used in current practice. Additional information on thermocouple system analysis will aid the user in developing accurate heat transfer measuring systems.

De Witt, R.J.

1983-01-01

196

Heat-transfer rate in the condenser section of a heat pipe  

Microsoft Academic Search

A dimensionless equation for calculation of the heat-transfer rate in the condenser of a heat pipe is derived on the basis of dimensional analyses of the fundamental convective heat-transfer equations. The experimental results are generalized.

V. Ya. Sasin; A. Ya. Shelginskii

1973-01-01

197

Intensified heat transfer in pipe with tall baffles  

Microsoft Academic Search

A model of the heat transfer in pipe with tall baffles is proposed, in conditions of intensified heat transfer. The model\\u000a takes account of various factors for a broad range of Prandtl numbers and Reynolds numbers.

I. E. Lobanov

2011-01-01

198

Modeling heat transfer within porous multiconstituent materials  

NASA Astrophysics Data System (ADS)

The purpose of our work has been to determine the effective thermal properties of materials considered heterogeneous at the microscale but which are regarded as homogenous in the macroscale environment in which they are used. We have developed a calculation code that renders it possible to simulate thermal experiments over complex multiconstituent materials from their numerical microstructural morphology obtained by volume segmentation through tomography. This modeling relies on the transient solving of the coupled conductive and radiative heat transfer in these voxelized structures.

Niezgoda, Mathieu; Rochais, Denis; Enguehard, Franck; Rousseau, Benoit; Echegut, Patrick

2012-06-01

199

Jet impingement heat transfer - A literature survey  

NASA Astrophysics Data System (ADS)

A literature survey had been carried out as part of background investigations relating to research by the author. The search was biased towards obtaining information concerning the heat transfer characteristics of round impinging jets, although slot nozzles were covered where relevant as were nonimpinging jets. This paper summarizes the findings of the literature review, covering forty-seven papers describing experimental investigations and theoretical analyses.

Downs, S. J.; James, E. H.

1987-08-01

200

Heat transfer augmentation in nanofluids via nanofins  

Microsoft Academic Search

Theoretical results derived in this article are combined with experimental data to conclude that, while there is no improvement\\u000a in the effective thermal conductivity of nanofluids beyond the Maxwell's effective medium theory (J.C. Maxwell, Treatise on Electricity and Magnetism, 1891), there is substantial heat transfer augmentation via nanofins. The latter are formed as attachments on the hot wire\\u000a surface by

Peter Vadasz

2011-01-01

201

Forced convection heat transfer to supercritical helium  

Microsoft Academic Search

We studied numerically the heat transfer for a turbulent flow of supercritical helium. A finite difference model is constructed\\u000a with three different models of turbulence: the mixing length,k- andk-? model. The stationary results compared to experimental data reveal that the mixing length model gives the best prediction\\u000a of turbulence in this situation. A severe deterioration from the widely used Nusselt

M. C. M. Cornelissen; C. J. Hoogendoorn

1985-01-01

202

Heat-transfer performance of a corrugated-tube thermosiphon. Part 1; Evaporator performance  

SciTech Connect

Two-phase closed thermosiphons are highly efficient heat-transfer elements with applications in terrestrial heat-transport and heat-recovery systems. In this paper, a corrugated copper tube was used as the container of the thermosiphons and distilled water was used as the working fluid. The influences of the liquid charge ratio and inclination angle on the heat-transfer performance were studied. It was found that the optimum liquid charge ratio to evaporator volume is 40 percent and the maximum performance is obtained at an inclination angle of 30 degrees. A useful formula to calculate the heat-transfer coefficient in the evaporator has been derived.

Negishi, K. (Tokyo Metropolitan Inst. of Technology (JP)); Kaneko, K. (Univ. of Osaka Prefecture (JP)); Matsuoka, T. (Nissan Motor Co., Ltd. (JP)); Hirashima, M.; Nishikawa, Y.; Taguchi, M. (Takuma Research and Development Co., Ltd. (JP))

1991-01-01

203

Heat transfer at interfaces with graphene  

NASA Astrophysics Data System (ADS)

Graphene has an ultrahigh in-plane thermal conductivity (5500 W/mK), but simultaneously a much lower conductivity along the c-axis in graphite or at the interfaces with other materials. As graphene finds more and more applications in nanoelectronics and high-performance composites, these interfaces become critically important in defining their heat dissipation and conduction performance. Unlike conventional interfaces in materials such as grain boundaries, the interfaces with graphene can be tuned by chemically modifying the graphene monolayer or intercalating the interfaces. These nano-engineering proposals require fundamental understanding of the heat transfer mechanisms. In order to obtain some insights on the transfer processes of mechanical and thermal energy across these interfaces, we perform series of molecular dynamics simulations, in combination with theoretical analysis by considering the quasi-ballistic nature of phonon transport at nanoscale. The result shows that heat dissipation or transport can be divided into two stages, beginning with an interface-controlled process. The effects of interface structures and binding properties on the whole process will be covered in this talk, with several examples showing how the interfacial thermal transfer can be engineered.

Xu, Zhiping

2012-02-01

204

The heat-transfer crisis in a closed evaporation thermosiphon  

Microsoft Academic Search

We determine the factors and conditions resulting in pronounced impairment of heat transfer through the cavity of a closed evaporation thermosiphon during the heat-transfer process. We have established the optimum conditions for the utilization of the heat-transfer elements.

N. M. Stoyanov

1969-01-01

205

Heat transfer from a high temperature condensable mixture  

Microsoft Academic Search

A new development in heat transfer is reported. It is concerned with heat transfer from a gaseous mixture that contains a condensable vapor and is at very high temperature. In the past, heat transfer associated with either a condensable mixture at low temperature or a noncondensable mixture at high temperature has been investigated. The former reduces to the classical problem

S. H. Chan; D. H. Cho; D. W. Condiff

1978-01-01

206

Non-conductive heat transfer associated with frozen soils  

Microsoft Academic Search

The assertion that pure conductive heat transfer always dominates in cold climates is at odds with decades of research in soil physics which clearly demonstrate that non-conductive heat transfer by water and water vapor are significant, and frequently are for specific periods the dominant modes of heat transfer near the ground surface. The thermal regime at the surface represents the

Douglas L Kane; Kenneth M Hinkel; Douglas J Goering; Larry D Hinzman; Samuel I Outcalt

2001-01-01

207

Heat Transfer in Glass, Aluminum, and Plastic Beverage Bottles  

ERIC Educational Resources Information Center

This paper addresses a controversy regarding the effect of bottle material on the thermal performance of beverage bottles. Experiments and calculations that verify or refute advertising claims and represent an interesting way to teach heat transfer fundamentals are described. Heat transfer coefficients and the resistance to heat transfer offered

Clark, William M.; Shevlin, Ryan C.; Soffen, Tanya S.

2010-01-01

208

Characterizations and Convective Heat Transfer Performance of Nanofluids  

Microsoft Academic Search

In recent years, many experimental studies have reported anomalous thermal conductivity enhancement and heat transfer increase in liquid suspensions of nanoparticles. In order to understand the mechanism of this phenomenon and examine the possible applications of nanofluids in heat transfer, the present study experimentally investigated thermal, rheological and heat transfer properties of nanofluids. In the first part of the work,

Yijun Yang

2011-01-01

209

Heat Transfer in Glass, Aluminum, and Plastic Beverage Bottles  

ERIC Educational Resources Information Center

|This paper addresses a controversy regarding the effect of bottle material on the thermal performance of beverage bottles. Experiments and calculations that verify or refute advertising claims and represent an interesting way to teach heat transfer fundamentals are described. Heat transfer coefficients and the resistance to heat transfer offered

Clark, William M.; Shevlin, Ryan C.; Soffen, Tanya S.

2010-01-01

210

FORCED CONVECTION HEAT TRANSFER CHARACTERISTICS OF POLYPHENYL REACTOR COOLANTS  

Microsoft Academic Search

In support of the Organic Moderated Reactor Experiment, forced-; connection heat transfer characteristics of several polyphenyls have been ; investigated in a laboratory heat transfer loop. Heat transfer runs were made ; with dipbenyl, Santowax R (commercial mixture of terphenyl isomers), and a 2: 1 ; mixture of Santowax 0 (commercial ortho-terphenyll and Santowax M (commercial ; metaterpbenyl). The operating

M. Silberberg; D. A. Huber

1959-01-01

211

46 CFR 153.430 - Heat transfer systems; general.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Heat transfer systems; general. 153.430...Control Systems § 153.430 Heat transfer systems; general. Each cargo...manual regulation of the system's heat transfer rate. [CGD 73-96, 42...

2010-10-01

212

46 CFR 153.430 - Heat transfer systems; general.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Heat transfer systems; general. 153.430...Control Systems § 153.430 Heat transfer systems; general. Each cargo...manual regulation of the system's heat transfer rate. [CGD 73-96, 42...

2009-10-01

213

Boiling heat transfer from an excavated fin  

SciTech Connect

In this paper a single pin fin with excavation at base is proposed to enhance boiling heat transfer. The temperature distribution in the fin is obtained numerically by solving a two-dimensional heat conduction equation. A copper fin boiling in isopropyl alcohol is taken as an example. When the operating temperature exceeds a specific value, the heat duty decreases drastically, and the whole fin is governed by film boiling. This highest operating temperature limit (burnout) is raised by digging a hole at the fin base. Two distinct solutions are found by using different initial guesses into the code. This hysteresis effect becomes noticeable for a bigger hole. A model is also developed to predict the burnout temperatures.

Liaw, S.P.; Yeh, R.H. (Dept. of Marine Engineering and Technology, National Taiwan Ocean Univ., Keelung (TW))

1992-03-01

214

Study on heat transfer of heat exchangers in the Stirling engine - Heat transfer in a heated tube under the periodically reversing flow condition  

NASA Astrophysics Data System (ADS)

Heat transfer characteristics in heated tubes under periodically reversing flow conditions have been experimentally investigated, using a test apparatus that simulates heat exchangers for an actual Stirling engine. It is shown that the heat transfer characteristics under these conditions are greatly affected by the piston phase difference that generates the reversing flow of working fluid, and this phenomenon is peculiar to heat transfer under periodically reversing flow. The experimental correlation for the heat transfer coefficient under these conditions is obtained through the use of the working gas velocity evaluated from the Schmidt cycle model, which is one of the ideal Stirling cycles concerning the influence of the piston phase difference.

Kanzaka, Mitsuo; Iwabuchi, Makio

1992-11-01

215

Development of the high performance phase change heat transfer system(II).  

National Technical Information Service (NTIS)

Experimental study on the closed two-phase thermosyphon loop system using the F-113 were performed. The results showed that the heat transfer efficiency was raising in accordance with increasing of the temperature difference between heat source and heat s...

Y. S. Yang D. W. Lee E. S. Yoon M. C. Ju

1994-01-01

216

High Efficiency Flat Panel Microchannel Heat Exchanger.  

National Technical Information Service (NTIS)

An apparatus providing high efficiency heat exchange between two fluids is disclosed. The apparatus most commonly comprises a flat panel with microchannels directing the flow of the two fluids, specifically: with a small hydraulic diameter in order to inc...

K. W. Kelly A. McCandless

2005-01-01

217

Efficient clocked electron transfer on superfluid helium.  

PubMed

Unprecedented transport efficiency is demonstrated for electrons on the surface of micron-scale superfluid helium-filled channels by co-opting silicon processing technology to construct the equivalent of a charge-coupled device. Strong fringing fields lead to undetectably rare transfer failures after over a billion cycles in two dimensions. This extremely efficient transport is measured in 120 channels simultaneously with packets of up to 20 electrons, and down to singly occupied pixels. These results point the way towards the large scale transport of either computational qubits or electron spin qubits used for communications in a hybrid qubit system. PMID:22243176

Bradbury, F R; Takita, Maika; Gurrieri, T M; Wilkel, K J; Eng, Kevin; Carroll, M S; Lyon, S A

2011-12-19

218

Testing efficiency transfer codes for equivalence.  

PubMed

Four general Monte Carlo codes (GEANT3, PENELOPE, MCNP and EGS4) and five dedicated packages for efficiency determination in gamma-ray spectrometry (ANGLE, DETEFF, GESPECOR, ETNA and EFFTRAN) were checked for equivalence by applying them to the calculation of efficiency transfer (ET) factors for a set of well-defined sample parameters, detector parameters and energies typically encountered in environmental radioactivity measurements. The differences between the results of the different codes never exceeded a few percent and were lower than 2% in the majority of cases. PMID:19892558

Vidmar, T; Celik, N; Cornejo Daz, N; Dlabac, A; Ewa, I O B; Carrazana Gonzlez, J A; Hult, M; Jovanovi?, S; Lpy, M-C; Mihaljevi?, N; Sima, O; Tzika, F; Jurado Vargas, M; Vasilopoulou, T; Vidmar, G

2009-10-17

219

Dynamic Model of Heat Transfer through Underground Building Envelope  

Microsoft Academic Search

Three-dimension dynamic differential heat conduction equation without inner heat source was used to describe heat transfer through underground building envelope. Then a two-dimension dynamic model was established by suitable simplification without considering heavy underground water. In this paper, in order to verify the model, MATLAB is chosen as the tool to simulate the heat transfer through envelope of Taiyuan underground

Jun Liu; Yan Jiang; Ying-Ai Jin

2010-01-01

220

A Model of Respiratory Heat Transfer in a Small Mammal  

PubMed Central

A steady-state model of the heat and water transfer occurring in the upper respiratory tract of the kangaroo rat, Dipodomys spectabilis, is developed and tested. The model is described by a steady-state energy balance equation in which the rate of energy transfer from a liquid stream (representing the flow of heat and blood from the body core to the nasal region) is equated with the rate of energy transfer by thermal conduction from the nose tip to the environment. All of the variables in the equation except the flow rate of the liquid stream can be either measured directly or estimated from physiological measurements, permitting the solution of the equation for the liquid stream flow rate. After solving for the liquid stream flow rate by using data from three animals, the energy balance equation is used to compute values of energy transfer, expired air temperature, rates of water loss, and efficiency of vapor recovery for a variety of ambient conditions. These computed values are compared with values measured or estimated from physiological measurements on the same three animals, and the equation is thus shown to be internally consistent. To evaluate the model's predictive value, calculated expired air temperatures are compared with measured expired air temperatures of eight additional animals. Finally, the model is used to examine the general dependence of expired air temperature, of rates of water loss, and of efficiency of vapor recovery on ambient conditions.

Collins, J. C.; Pilkington, T. C.; Schmidt-Nielsen, K.

1971-01-01

221

Heat Transfer Investigation of Liquid and Two-Phase Methane.  

National Technical Information Service (NTIS)

A heat transfer investigation was conducted for liquid and two-phase methane. The tests were conducted at the NASA Glenn Research Center Heated Tube Facility (HTF) using resistively heated tube sections to simulate conditions encountered in regeneratively...

J. VanNoord

2010-01-01

222

Infrared thermography for convective heat transfer measurements  

NASA Astrophysics Data System (ADS)

This paper deals with the evolution of infrared (IR) thermography into a powerful optical tool that can be used in complex fluid flows to either evaluate wall convective heat fluxes or investigate the surface flow field behavior. Measurement of convective heat fluxes must be performed by means of a thermal sensor, where temperatures have to be measured with proper transducers. By correctly choosing the thermal sensor, IR thermography can be successfully exploited to resolve convective heat flux distributions with both steady and transient techniques. When comparing it to standard transducers, the IR camera appears very valuable because it is non-intrusive, it has a high sensitivity (down to 20 mK), it has a low response time (down to 20 ?s), it is fully two dimensional (from 80 k up to 1 M pixels, at 50 Hz) and, therefore, it allows for better evaluation of errors due to tangential conduction within the sensor. This paper analyses the capability of IR thermography to perform convective heat transfer measurements and surface visualizations in complex fluid flows. In particular, it includes the following: the necessary radiation theory background, a review of the main IR camera features, a description of the pertinent heat flux sensors, an analysis of the IR image processing methods and a report on some applications to complex fluid flows, ranging from natural convection to hypersonic regime.

Carlomagno, Giovanni Maria; Cardone, Gennaro

2010-12-01

223

Van der Waals interaction-tuned heat transfer in nanostructures  

NASA Astrophysics Data System (ADS)

Interfaces usually impede heat transfer in heterogeneous structures. Recent experiments show that van der Waals (vdW) interactions can significantly enhance thermal conductivity parallel to the interface of a bundle of nanoribbons compared to a single layer of freestanding nanoribbon. In this paper, by simulating heat transfer in nanostructures based on a model of nonlinear one-dimensional lattices interacting via van der Waals interactions, we show that the vdW interface interaction can adjust the thermal conductivity parallel to the interface. The efficiency of the adjustment depends on the intensity of interactions and temperature. The nonlinear dependence of the conductivity on the intensity of interactions agrees well with experimental results for carbon nanotube bundles, multi-walled carbon nanotubes, multi-layer graphene, and nanoribbons.

Sun, Tao; Wang, Jianxiang; Kang, Wei

2012-12-01

224

A review of turbine blade tip heat transfer.  

PubMed

This paper presents a review of the publicly available knowledge base concerning turbine blade tip heat transfer, from the early fundamental research which laid the foundations of our knowledge, to current experimental and numerical studies utilizing engine-scaled blade cascades and turbine rigs. Focus is placed on high-pressure, high-temperature axial-turbine blade tips, which are prevalent in the majority of today's aircraft engines and power generating turbines. The state of our current understanding of turbine blade tip heat transfer is in the transitional phase between fundamentals supported by engine-based experience, and the ability to a priori correctly predict and efficiently design blade tips for engine service. PMID:11460670

Bunker, R S

2001-05-01

225

Boiling Heat Transfer Characteristics with Highly Wettable Heated Surface under Forced Convection Conditions  

Microsoft Academic Search

Under forced convection and atmospheric pressure conditions, heat transfer characteristics were studied using an annulus channel of a heater rod with highly-wettable surface. Improvement of phase change heat transfer under boiling and condensation process requires that either liquid heated or vapor cooled can contact a heat transfer surface effectively, but either a vapor layer or a liquid film can be

Toru Mitsutake; Fumihisa Kano; Tetsuo Oosato; Akio Sayano; Miyuki Akiba; Shinichi Morooka

2004-01-01

226

Hydrodynamics and heat transfer in swirl flow under conditions of one-side heating. Part 2: Boiling heat transfer. Critical heat fluxes  

Microsoft Academic Search

The paper gives the basic results of experimental investigation of boiling heat transfer in heat-absorbing devices of the ITER thermonuclear reactor, which are subjected to one-side heating. The experimental data on heat transfer at nucleate and film boiling and on critical heat fluxes are obtained in the following range of parameters of water flow: pressure p=0.72.0MPa, mass flux G=34025000kg\\/(m2s), and

Aleksey V. Dedov; Alexander T. Komov; Alexander N. Varava; Victor V. Yagov

2010-01-01

227

Handbook of heat and mass transfer. Volume 2  

Microsoft Academic Search

This two-volume series, the work of more than 100 contributors, presents advanced topics in industrial heat and mass transfer operations and reactor design technology. Volume 2 emphasizes mass transfer and reactor design. Some of the contents discussed are: MASS TRANSFER PRINCIPLES - Effect of turbulence promoters on mass transfer. Mass transfer principles with homogeneous and heterogeneous reactions. Convective diffusion with

Cheremisinoff

1986-01-01

228

Heat transfer augmentation in nanofluids via nanofins.  

PubMed

Theoretical results derived in this article are combined with experimental data to conclude that, while there is no improvement in the effective thermal conductivity of nanofluids beyond the Maxwell's effective medium theory (J.C. Maxwell, Treatise on Electricity and Magnetism, 1891), there is substantial heat transfer augmentation via nanofins. The latter are formed as attachments on the hot wire surface by yet an unknown mechanism, which could be related to electrophoresis, but there is no conclusive evidence yet to prove this proposed mechanism. PMID:21711695

Vadasz, Peter

2011-02-18

229

Heat transfer augmentation in nanofluids via nanofins  

NASA Astrophysics Data System (ADS)

Theoretical results derived in this article are combined with experimental data to conclude that, while there is no improvement in the effective thermal conductivity of nanofluids beyond the Maxwell's effective medium theory (J.C. Maxwell, Treatise on Electricity and Magnetism, 1891), there is substantial heat transfer augmentation via nanofins. The latter are formed as attachments on the hot wire surface by yet an unknown mechanism, which could be related to electrophoresis, but there is no conclusive evidence yet to prove this proposed mechanism.

Vadasz, Peter

2011-12-01

230

Heat transfer augmentation in nanofluids via nanofins  

PubMed Central

Theoretical results derived in this article are combined with experimental data to conclude that, while there is no improvement in the effective thermal conductivity of nanofluids beyond the Maxwell's effective medium theory (J.C. Maxwell, Treatise on Electricity and Magnetism, 1891), there is substantial heat transfer augmentation via nanofins. The latter are formed as attachments on the hot wire surface by yet an unknown mechanism, which could be related to electrophoresis, but there is no conclusive evidence yet to prove this proposed mechanism.

2011-01-01

231

Convective heat transfer and infrared thermography.  

PubMed

Infrared (IR) thermography, because of its two-dimensional and non-intrusive nature, can be exploited in industrial applications as well as in research. This paper deals with measurement of convective heat transfer coefficients (h) in three complex fluid flow configurations that concern the main aspects of both internal and external cooling of turbine engine components: (1) flow in ribbed, or smooth, channels connected by a 180 degrees sharp turn, (2) a jet in cross-flow, and (3) a jet impinging on a wall. The aim of this study was to acquire detailed measurements of h distribution in complex flow configurations related to both internal and external cooling of turbine components. The heated thin foil technique, which involves the detection of surface temperature by means of an IR scanning radiometer, was exploited to measure h. Particle image velocimetry was also used in one of the configurations to precisely determine the velocity field. PMID:12496015

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

2002-10-01

232

Heat transfer in nucleate pool boiling of multicomponent mixtures  

Microsoft Academic Search

Steady state pool boiling heat transfer coefficients have been obtained experimentally for acetone-isopropanol-water and ace- tone-MEK (methyl ethyl ketone)-water ternary systems. The data show that, for a given heat flux, the heat transfer coefficients of mixtures are lower than those obtained for pure components constituting the mixture. The measured heat transfer coefficients were compared with predictions from literature correlations for

G. Vinayak Rao; A. R. Balakrishnan

2004-01-01

233

Heat transfer in nucleate pool boiling of multicomponent mixtures  

Microsoft Academic Search

Steady state pool boiling heat transfer coefficients have been obtained experimentally for acetoneisopropanolwater and acetoneMEK (methyl ethyl ketone)water ternary systems. The data show that, for a given heat flux, the heat transfer coefficients of mixtures are lower than those obtained for pure components constituting the mixture. The measured heat transfer coefficients were compared with predictions from literature correlations for pool

G. Vinayak Rao; A. R. Balakrishnan

2004-01-01

234

Heat Transfer from Pin-Fin Heat Sinks under Multiple Impinging Jets  

Microsoft Academic Search

The enhancement of heat transfer from a discrete heat source using multiple jet impingement of air in a confined arrangement was experimentally investigated. A variety of pin-fin heat sinks were mounted on the heat source and the resulting enhancement studied. Average heat transfer coefficients are presented for a range of jet Reynolds numbers (2000 < Re < 23000). Two jet-to-jet

H. A. El-Sheikh; S V Garimella

2001-01-01

235

Compact Modeling of Fluid Flow and Heat Transfer in Pin Fin Heat  

Microsoft Academic Search

is presented. Its application to the analysis of fluid flow and heat transfer in pin fin heat sinks are further analyzed. The pin fin heat sink is modeled as a porous medium. The volume-averaged momentum and energy equations for fluid flow and heat transfer in pin fin heat sinks are obtained by using the local volume-averaging method. The permeability, the

Duckjong Kim; Sung Jin Kim; Alfonso Ortega

2004-01-01

236

Heat Transfer Steady and Transient Characteristics in Flat Plate Micro Heat Pipe  

NASA Astrophysics Data System (ADS)

Recently, the newly developed flat type micro heat pipe (,,HP) attracts attention, because of easy installation in PC and the assurance of the enough contact area. In this research, an experimental study is done to investigate the heat transfer steady characteristics of this heat transfer device in detail and finally, a prediction method of maximum heat transfer capacity is proposed. Since the heat pipe operation must be started from the ambient temperature in practice, depending on the needs of a designer, heat transfer transient characteristic is also a matter of concern. Therefore in order to observe the response of heat pipe to a step heat input, transient tests are done.

Katsuta, Masafumi; Shindo, Tomoya; Saito, Kouichiro; Shinohara, Takero; Jalivand, Ahmad; Kimura, Yuichi; Nakamura, Yoshio; Sotani, Junji

237

Transectional heat transfer in thermoregulating bigeye tuna (Thunnus obesus) - a 2D heat flux model.  

PubMed

We developed a 2D heat flux model to elucidate routes and rates of heat transfer within bigeye tuna Thunnus obesus Lowe 1839 in both steady-state and time-dependent settings. In modeling the former situation, we adjusted the efficiencies of heat conservation in the red and the white muscle so as to make the output of the model agree as closely as possible with observed cross-sectional isotherms. In modeling the latter situation, we applied the heat exchanger efficiencies from the steady-state model to predict the distribution of temperature and heat fluxes in bigeye tuna during their extensive daily vertical excursions. The simulations yielded a close match to the data recorded in free-swimming fish and strongly point to the importance of the heat-producing and heat-conserving properties of the white muscle. The best correspondence between model output and observed data was obtained when the countercurrent heat exchangers in the blood flow pathways to the red and white muscle retained 99% and 96% (respectively) of the heat produced in these tissues. Our model confirms that the ability of bigeye tuna to maintain elevated muscle temperatures during their extensive daily vertical movements depends on their ability to rapidly modulate heating and cooling rates. This study shows that the differential cooling and heating rates could be fully accounted for by a mechanism where blood flow to the swimming muscles is either exclusively through the heat exchangers or completely shunted around them, depending on the ambient temperature relative to the body temperature. Our results therefore strongly suggest that such a mechanism is involved in the extensive physiological thermoregulatory abilities of endothermic bigeye tuna. PMID:19880733

Boye, Jess; Musyl, Michael; Brill, Richard; Malte, Hans

2009-11-01

238

Surface condition effects on flame impingement heat transfer  

Microsoft Academic Search

Flame impingement heating is used in many industrial applications, including the heating and melting of both glass and metal. This heating process usually comprises multiple heat transfer mechanisms, such as forced convection, thermal radiation, and thermochemical heat release. However, little experimental data are available that can be used to determine the importance of each mechanism. This information would be useful

C. E. Baukal; B. Gebhart

1997-01-01

239

Heat and mass transfer in the gas tungsten and gas metal arc welding processes  

SciTech Connect

The heat transferred from an electrode negative, argon gas tungsten arc to an anode was measured for a wide range of conditions suitable for mechanized welding. The results are given as (1) the arc efficiency and (2) the anode heat and current input distributions for various anode materials over a range of current and voltage. The nominal arc is Gaussian, {approximately}4 mm in diameter, with {approximately}75{percent}heat transfer efficiency. Variations from these values are discussed in terms of the electrical and thermal energy transport mechanisms. Heat transferred to the workpiece (cathode) during direct current, electrode positive gas metal arc welding (GMAW) was measured for various parameters applicable to machine welding. The results are presented as a function of electrode speed for changing voltages and contact tip to workpiece distances. The total heat transfer efficiency was nominally 85{percent} for a 0.89 mm diameter steel electrode using an argon-2{percent} oxygen shielding gas; the nominal heat transfer efficiency of the droplet component was 40{percent}. The average droplet temperatures ranged from 2400 to 3100 K, depending on the process parameters. A new method of measuring the heat transferred from the arc to the workpiece, using a boiling liquid nitrogen calorimeter, has been developed that gives rapid, accurate values. 20 refs., 8 figs., 2 tabs.

Watkins, A.D; Smartt, H.B.; Einerson, C.J.; Watkins, J.A.

1990-01-01

240

Heat transfer from extended surfaces subject to variable heat transfer coefficient  

Microsoft Academic Search

The present article investigates the effect of locally variable heat transfer coefficient on the performance of extended surfaces (fins) subject to natural convection. Fins of different profiles have been investigated. The fin profiles presently considered are namely; straight and pin fin with rectangular (constant diameter), convex parabolic, triangular (conical) and concave parabolic profiles and radial fins with constant profile with

Esmail M. A. Mokheimer

2003-01-01

241

Heat Transfer Enhancement in a Pipe Using a Flow Inverter  

Microsoft Academic Search

Flow inversion, transferring a liquid from the wall region toward the center of the pipe or from the axis toward the heat transfer surface, improves heat transfer in the laminar flow regime. While a fully developed velocity profile is quickly established, a thin thermal boundary layer is preserved for a considerable distance in the pipe behind the flow inverter for

Rudolf itn; Thi Cam Tu Luong; Jir estk

2009-01-01

242

Analysis of edge heat transfer in residential windows.  

National Technical Information Service (NTIS)

New window technologies are reducing heat transfer through the glazed areas of windows. Low-emissivity (low-E) coatings reduce radiative heat transfer and low-conductivity gas fills (which replace the air between glazing layers) reduce conductive heat tra...

D. Arasteh

1989-01-01

243

Experimental study of heat transfer in oscillating flow  

Microsoft Academic Search

This paper describes an experimental study of heat transfer in oscillating flow inside a cylindrical tube. Profiles of temperature are taken inside the wall and in the fluid from an instrumented test rig, in different conditions of oscillating flow. Profiles obtained allow the observation of the wall effect on heat transfer. A method using the inverse heat conduction principle allows

Pascale Bouvier; Pascal Stouffs; Jean-Pierre Bardon

2005-01-01

244

Heat transfer in serpentine flow passages with rotation  

Microsoft Academic Search

Heat transfer characteristics of a three-pass serpentine flow passage with rotation are experimentally studied. The walls of the square flow passage are plated with thin stainless-steel foils through which electrical current is applied to generate heat. The local heat transfer performance on the four side walls of the three straight flow passages and two turning elbows are determined for both

S. Mochizuki; J. Takamura; S. Yamawaki; Wen-Jei Yang

1994-01-01

245

Challenges in microscale conductive and radiative heat transfer  

Microsoft Academic Search

This work addresses challenges in the emerging field of microlength scale radiative and conductive heat transfer in solids and recommends specific directions of future research. Microlength scale heat transfer involves thermal energy transport processes in which heat carrier characteristic lengths become comparable to each other or the characteristic device dimension. Identification of these characteristic lengths leads to the definition of

C. L. Tien; G. Chen

1994-01-01

246

Upflow turbulent mixed convection heat transfer in vertical pipes  

Microsoft Academic Search

The present work deals with the results of an experimental investigation on heat transfer in water cooled vertical pipes, for thermalhydraulic conditions ranging from forced convective flow to mixed convective flow. The flow of water in the pipe is upwards.Experimental data confirm the reduction in the heat transfer rate for mixed convection in upward heat flow, mainly due to the

Gian Piero Celata; Francesco Dannibale; Andrea Chiaradia; Maurizio Cumo

1998-01-01

247

Convective heat transfer area of the human body  

Microsoft Academic Search

In order to clarify the heat transfer area involved in convective heat exchange for the human body, the total body surface area of six healthy subjects was measured, and the non-convective heat transfer area and floor and chair contact areas for the following nine common body positions were measured: standing, sitting on a chair, sitting in the seiza position, sitting

Yoshihito Kurazumi; Tadahiro Tsuchikawa; Naoki Matsubara; Tetsumi Horikoshi

2004-01-01

248

Heat Transfer Characteristics of Pin-Fin Arrays with Ribs to Cool Combustor Liners  

NASA Astrophysics Data System (ADS)

Enhancement of heat transfer by pin-fin channels with turbulence promoters has been investigated with an aim to improve the cooling efficiency of combustor liners in gas turbines. Time-mean local Nusselt number profiles were obtained by naphthalene sublimation technique based on the heat/mass transfer analogy for Reynolds numbers ranging from 1000-10000. Two oblique rib-type turbulence promoters were tested and compared with no-rib cases. In addition, steady three-dimensional numerical simulations using a RANS model were performed. Installation of turbulence promoters is found to be effective in increasing the endwall heat transfer rate widely and uniformly. In addition, the ribs enhance heat transfer, especially in developing regions at the first and second pin-fin rows. Local high heat transfer regions were obtained in front of the ribs due to horseshoe vortices and downstream of the pins due to a longitudinal vortex.

Oda, Yutaka; Takeishi, Kenichiro; Motoda, Yusuke; Sugimoto, Shinsuke; Miyake, Yoshiaki

249

Control of Impingement Heat Transfer Using Mist  

NASA Astrophysics Data System (ADS)

Impingement heat transfer from a circular orifice jet by using latent heat of water mists was studied experimentally. The amounts of mists of about Zauter's mean diameter 14 m were from 60 to 200 g/h within a range where liquid films were not formed on the target plate and mists were added near the orifice edge. Experiments covered Reynolds numbers from 12,500 to 50,000 and a heat flux is 1,400 W/m2. The experimental results indicate that adding mists had little influence on free jet mean velocity profiles and target plate pressure coefficients. On the other hand, mists had a strong influence on temperature and humidity profiles of a free jet and they also influenced Nusselt number distributions on the target plate. Increases of mists and Reynolds number caused increases in Nusselt number on the developed region. In addition, we investigated influence of the way mists were added and these results showed that Nusselt number was influenced not only by the amounts of mists but also by the adding method. Local Nusselt number profiles with mists were closely related to temperature distributions of the free jet at the location corresponding to the target plate.

Kanamori, Azusa; Hiwada, Munehiko; Mimatsu, Junji; Sugimoto, Hiraku; Oyakawa, Kenyuu

250

Convective heat transfer in porous media  

NASA Astrophysics Data System (ADS)

Recent emerging technologies on the extraction of geothermal energy, the design of insulation systems for energy conservation, the use of aquifers for hot-water storage, the disposal of nuclear wastes in sub-seabeds, the enhanced recovery of oils by thermal methods, and the design of catalyst-bed reactors have demanded an improved understanding of heat transfer mechanisms in fluid-filled porous media. Experiments have been conducted to investigate the onset of free convection in rectangular and cylindrical enclosures filled with porous media and heated from below. The Nusselt numbers determined from these experiments during steady conditions are correlated in terms of the Rayleigh number. The data for free convection in rectangular geometries show considerable scattering among investigators using different porous media and fluids. Recently, some data has been obtained for free convect on in water-filled glass beads adjacent to a heated vertical flat plate, a horizontal cylinder and between vertical concentric cylinders. The data obtained at low Rayleigh numbers is found to be in good agreement with theoretical predictions based on Darcy's law.

Cheng, P.

251

Understanding fast heat transfer in the shallow subsurface  

NASA Astrophysics Data System (ADS)

Understanding the temperature profile of the shallow subsurface is of great importance for interpreting remote sensing observations and modeling land-atmosphere interaction. Remote sensing observations are translated to surface characteristics, such as vegetation and soil moisture, using radiative transfer schemes that are sensitive to skin temperature estimation. The surface temperature is also a key variable in the heat partitioning of net radiation into sensible, latent and soil heat flux at the interface between land and atmosphere. The temperature profile of the soil is determined by the processes of radiative, convective and conductive heat transfer. Whereas radiative and convective heat transfer are dominant at the soil-air interface, heat transfer within the soil is typically assumed to be governed by conduction and as such is described with a diffusion model. The thermal diffusivity of the soil depends mainly on mineral composition and moisture content and is described in many empirical models. Using temperature data from experiments conducted in Florida (MicroWex 2) and the Netherlands (Monster), we show that diffusion cannot describe heat transfer within approximately the upper ten centimeters of the soil. The heat transfer is significantly faster than would be predicted with a diffusion equation. Diffusivity values, estimated using an inversion approach to the diffusion equation, fall outside the physically reasonable range, which is defined by available soil diffusivity models. The extent of this strongly thermally active layer depends on vegetation conditions, and possibly moisture conditions. We investigate mechanisms that may explain the fast heat transfer in the shallow subsurface. Possible mechanisms include heat transfer by convective heat transfer processes such as latent heat formation and heat transfer due to water percolation. We estimated the size of the heat sink-source at depth and compared these to observations of latent heat and estimates of heat transfer by percolation. The magnitude of the sink-source reached values up to the same order of magnitude as the latent heat flux and decreased with depth. The sink-source terms were large, especially for low vegetation conditions and showed a distinct diurnal cycle. The possible contribution of percolation to heat transfer was minor compared to the magnitude of the sink-source term. Finally, we compared an empirical heat flow model, which includes formation of latent heat in the shallow subsurface, with our data. We found this model could not sufficiently describe the fast heat transfer in the shallow subsurface. Ongoing work is on a physically based model to describe fast heat transfer in the shallow subsurface.

Rutten, Martine; Steele-Dunne, Susan; Judge, Jasmeet; van de Giesen, Nick

2010-05-01

252

Heat exchanger efficiently operable alternatively as evaporator or condenser  

DOEpatents

A heat exchanger adapted for efficient operation alternatively as evaporator or condenser and characterized by flexible outer tube having a plurality of inner conduits and check valves sealingly disposed within the outer tube and connected with respective inlet and outlet master flow conduits and configured so as to define a parallel flow path for a first fluid such as a refrigerant when flowed in one direction and to define a serpentine and series flow path for the first fluid when flowed in the opposite direction. The flexible outer tube has a heat exchange fluid, such as water, flowed therethrough by way of suitable inlet and outlet connections. The inner conduits and check valves form a package that is twistable so as to define a spiral annular flow path within the flexible outer tube for the heat exchange fluid. The inner conduits have thin walls of highly efficient heat transfer material for transferring heat between the first and second fluids. Also disclosed are specific materials and configurations.

Ecker, Amir L. (Dallas, TX)

1981-01-01

253

EFFICIENT THREE-DIMENSIONAL NLTE DUST RADIATIVE TRANSFER WITH SKIRT  

SciTech Connect

We present an updated version of SKIRT, a three-dimensional (3D) Monte Carlo radiative transfer code developed to simulate dusty galaxies. The main novel characteristics of the SKIRT code are the use of a stellar foam to generate random positions, an efficient combination of eternal forced scattering and continuous absorption, and a new library approach that links the radiative transfer code to the DustEM dust emission library. This approach enables a fast, accurate, and self-consistent calculation of the dust emission of arbitrary mixtures of transiently heated dust grains and polycyclic aromatic hydrocarbons, even for full 3D models containing millions of dust cells. We have demonstrated the accuracy of the SKIRT code through a set of simulations based on the edge-on spiral galaxy UGC 4754. The models we ran were gradually refined from a smooth, two-dimensional, local thermal equilibrium (LTE) model to a fully 3D model that includes non-LTE (NLTE) dust emission and a clumpy structure of the dusty interstellar medium. We find that clumpy models absorb UV and optical radiation less efficiently than smooth models with the same amount of dust, and that the dust in clumpy models is on average both cooler and less luminous. Our simulations demonstrate that, given the appropriate use of optimization techniques, it is possible to efficiently and accurately run Monte Carlo radiative transfer simulations of arbitrary 3D structures of several million dust cells, including a full calculation of the NLTE emission by arbitrary dust mixtures.

Baes, Maarten; Verstappen, Joris; De Looze, Ilse; Fritz, Jacopo; Saftly, Waad; Vidal Perez, Edgardo; Stalevski, Marko; Valcke, Sander, E-mail: maarten.baes@ugent.BE [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281-S9, B-9000 Gent (Belgium)

2011-10-01

254

Combined conduction and radiation heat transfer in porous materials heated by intense solar radiation  

Microsoft Academic Search

An analysis is presented to predict the heat transfer characteristics of a plane layer of a semitransparent, high-temperature, porous material which is irradiated by an intense solar flux. A transient, combined conduction and radiation heat transfer model, which is based on a two-flux approximation for the radiation, is used to predict the temperature distribution and heat transfer in the material.

L. K. Matthews; F. P. Incropera; R. Viskanta

1985-01-01

255

Energy efficiency improvement of dryer section heat recovery systems in paper machines A case study  

Microsoft Academic Search

Modern paper machines are equipped with heat recovery systems that transfer heat from the humid exhaust air of the paper machines dryer section to different process streams. As a result of process changes, the heat recovery systems may operate in conditions far from the original design point, creating a significant potential for energy efficiency improvement. In this paper we demonstrate

Leena Sivill; Pekka Ahtila

2009-01-01

256

Analysis of heat losses and ways to improve the efficiency of solar-array thermoelectric generators  

Microsoft Academic Search

Ways to improve the efficiency of solar thermoelectric generators by reducing heat losses are discussed. Different heat transfer conditions are examined: single and double layer glass coatings, selective coatings on the collector, ordinary and vacuum-type heat insulation, and air and water cooling.

I. I. Kokhova; Iu. N. Malevskii; A. I. Tsvetkov

1980-01-01

257

Effects of the rough surface structure on heat transfer in turbulent thermal convection  

NASA Astrophysics Data System (ADS)

Heat transfer between a solid surface and a fluid medium affects many engineering applications ranging from heat exchangers to reentry vehicles in the space flight. In many cases, the heat transport is limited by a thin thermal boundary layer of fluid near the solid surface. Further away from this surface, the fluid is turbulent and hence the heat transfer rate is fast. In a series of controlled convection experiments, we measure the heat transport of turbulent convection in a cell with rough upper and lower surfaces. We study how the lateral structure of the rough surface affects the heat transport. We have examined the rough surfaces made of parallel grooves, woven grooves, a layer of closely packed brass spheres, and a layer of loosely packed brass spheres. It is found that the woven groove structure gives the maximum enhanced heat transport when compared with the smooth surface, which transfers heat least efficiently. The loose pack of spheres is found to be the second most efficient surface for the heat transport. These measurements shed new light on technological improvements for more efficient heat transfer in industrial applications. This work is supported by NSF DMR-0071323.

Treeman, Jodie M.; Qiu, Xinliang; Tong, Penger

2001-11-01

258

Effect of Condesation in Clothing on Heat Transfer  

National Technical Information Service (NTIS)

A condensation theory is presented, that enables the calculation of the rate of vapour transfer with its associated effects on temperature and total heat transfer, inside a clothing ensemble consisting of underclothing, enclosed air, and outer garment. Th...

F. J. Van De Linde G. Havenith W. A. Lotens

1990-01-01

259

Heat transfer in freeboard region of fluidized beds  

SciTech Connect

This research involved the study of heat transfer and fluid mechanic characteristics around a horizontal tube in the freeboard region of fluidized beds. Heat transfer coefficients were experimetnally measured for different bed temperatures, particle sizes, gas flow rates, and tube elevations in the freeboard region of air fluidized beds at atmospheric pressure. Local heat transfer coefficients were found to vary significantly with angular position around the tube. Average heat transfer coefficients were found to decrease with increasing freeboard tube elevation and approach the values for gas convection plus radiation for any given gas velocity. For a fixed tube elevation, heat transfer coefficients generally increased with increasing gas velocity and with high particle entrainment they can approach the magnitudes found for immersed tubes. Heat transfer coefficients were also found to increase with increasing bed temperature. It was concluded that this increase is partly due to increase of radiative heat transfer and partly due to change of thermal properties of the fluidizing gas and particles. To investigate the fluid mechanic behavior of gas and particles around a freeboard tube, transient particle tube contacts were measured with a special capacitance probe in room temperature experiments. The results indicated that the tube surface experiences alternating dense and lean phase contacts. Quantitative information for local characteristics was obtained from the capacitance signals and used to develop a phenomenological model for prediction of the heat transfer coefficients around freeboard tubes. The packet renewal theory was modified to account for the dense phase heat transfer and a new model was suggested for the lean phase heat transfer. Finally, an empirical freeboard heat transfer correlation was developed from functional analysis of the freeboard heat transfer data using nondimensional groups representing gas velocity and tube elevation.

Biyikli, S.; Tuzla, K.; Chen, J.C.

1983-10-01

260

Turbulence management using riblets for heat and momentum transfer  

Microsoft Academic Search

Experiments were carried out in a low-speed wind tunnel to investigate the heat-transfer characteristics of triangular-profiled riblet surfaces by comparing them with those of a smooth surface of an identical construction in a thermal turbulent boundary layer. The results of careful heat-transfer measurements indicate that the heat-transfer coefficient over riblet surfaces is increased from that of a smooth surface by

K.-S Choi; D. M Orchard

1997-01-01

261

Mass transfer in oscillating flows: Efficient drying via pulse combustors  

NASA Astrophysics Data System (ADS)

The study addressed analytical and experimental methods for increasing industrial and home drying efficiency via pulse combustors. A fundamental scientific methodology is being developed for the momentum, heat and mass transfer in oscillating (on the mean) turbulent flows. The approach follows the intuitive ideas of Taylor and Kolmogorov on the construction of microscales of turbulence. A parallel experimental program is being carried out by the pulse combustor of the Continuous Combustion Laboratory of the Sandia-Livermore National Laboratories. A droplet sizing technique and a quasi-steady computer model have been developed. The unsteady analytical model will determine the range of the quasi-steady model and provide also a mass transfer correlation beyond this range.

Arpaci, V. S.; Gemmen, R.; Selamet, A.

1989-04-01

262

Low-melting point heat transfer fluid  

DOEpatents

A low-melting point, heat transfer fluid comprising a mixture of LiNO.sub.3, NaNO.sub.3, KNO.sub.3, NaNO.sub.2 and KNO.sub.2 salts where the Li, Na and K cations are present in amounts of about 20-33.5 mol % Li, about 18.6-40 mol % Na, and about 40-50.3 mol % K and where the nitrate and nitrite anions are present in amounts of about 36-50 mol % NO.sub.3, and about 50-62.5 mol % NO.sub.2. These compositions can have liquidus temperatures between 70.degree. C. and 80.degree. C. for some compositions.

Cordaro, Joseph G. (Oakland, CA); Bradshaw, Robert W. (Livermore, CA)

2011-04-12

263

Turbine disk cavity aerodynamics and heat transfer  

NASA Astrophysics Data System (ADS)

Experiments were conducted to define the nature of the aerodynamics and heat transfer for the flow within the disk cavities and blade attachments of a large-scale model, simulating the Space Shuttle Main Engine (SSME) turbopump drive turbines. These experiments of the aerodynamic driving mechanisms explored the following: (1) flow between the main gas path and the disk cavities; (2) coolant flow injected into the disk cavities; (3) coolant density; (4) leakage flows through the seal between blades; and (5) the role that each of these various flows has in determining the adiabatic recovery temperature at all of the critical locations within the cavities. The model and the test apparatus provide close geometrical and aerodynamic simulation of all the two-stage cavity flow regions for the SSME High Pressure Fuel Turbopump and the ability to simulate the sources and sinks for each cavity flow.

Johnson, B. V.; Daniels, W. A.

1992-07-01

264

Heat transfer characteristics in film cooling applications  

NASA Astrophysics Data System (ADS)

The leading edge region of gas turbine blades and vanes experiences high thermal and mechanical stresses and has to be properly cooled. External cooling of the leading edge region is typically achieved by a film cooling technique. An investigation into the film cooling effectiveness of three different large scale leading edge geometries is presented in this study. One of the geometries investigated represents an original design and is an example of an improved film cooling layout. AD geometries used have four rows of cooling holes placed symmetrically about the geometrical leading edge, but the layout of the cooling holes is different from one leading edge geometry to another. A broad range of variables is considered including mass flow ratio, coolant density, and jet Reynolds number. Film cooling effectiveness measurements were made in a low speed wind tunnel environment using a flame ionization detector technique and the mass/heat transfer analogy. These measurements significantly extend the insight into the effects of hole geometry on the film cooling characteristics of the leading edge of turbine blades and provide new data for design purposes. The effect of geometry is more important for the case of double row injection where spanwise-averaged film cooling effectiveness is improved by the use of compound angle holes. The spanwise-averaged film cooling effectiveness is higher at lower mass flow ratios and decreases typically as the mass flow ratio increases. At higher mass flow ratios, the newly designed leading edge geometry produces higher spanwise-averaged film cooling effectiveness than the other two geometries investigated thus providing the necessary backflow margin at operating conditions more relevant to gas turbine use. For the case of single row injection, the effects of geometry scale reasonably well when the local mass flow ratio is used in the analysis of the spanwise-averaged film cooling effectiveness immediately downstream of the injection holes. The local momentum flux ratio is a more appropriate scaling parameter when coolants with different densities are used. A film cooling effectiveness correlation was also developed for one of the geometries investigated based on an area-averaged film cooling effectiveness and on a newly defined blowing parameter. This correlation accounts implicitly for the particular geometrical layout used and explicitly for the main injection parameters investigated. The results can be now more directly used in existing design procedures. A new experimental technique based on wide-band liquid crystal thermography and transient one-dimensional heat conduction has been developed and implemented. The technique combines a real-time, true colour imaging system with the use of a wide-band liquid crystal and multiple event sampling for the simultaneous determination of the film cooling effectiveness and heat transfer coefficient from one transient test. A comparison of different image capture techniques is also presented and computer codes are developed for data processing. For a test case of compound angle square jets in a crossflow, very good agreement was obtained between the film cooling effectiveness calculated from the transient heat transfer experiments and the film cooling effectiveness measured in isothermal mass transfer experiments using a flame ionization detector technique. This new approach has been developed as a major part of this thesis and represents a significant contribution to the use of liquid crystal thermography in film cooling applications.

Licu, Dragos Nicolae

1998-11-01

265

Heat transfer in open cell foam insulation  

SciTech Connect

Heat transfer in open cell foam insulation occurs by conduction through the solid material and though the gas in the cell interior and by thermal radiation, which propagates through the structure. The conductive process within these media is described using a simple parallel-series model. Spectral volumetric absorption and scattering coefficients as well as the spectral phase function are predicted using a combination of geometric optics laws and diffraction theory to model the interaction of radiation with the particles forming the foam. The particles considered are both struts formed at the juncture of three cells and strut junctures. The radiative properties can then be utilized to obtain a weighted extinction coefficient, which can be used in the Rosseland equation to obtain the radiative flux. The innovative part of the work lies in the radiative properties predictive model. This new model is compared with simpler ones. 21 refs., 6 figs., 4 tabs.

Doermann, D.; Sacadura, J.F. [Centre de Thermique-URA CNRS, Villeurbanne (France)

1996-02-01

266

Cleaning and Heat Transfer in Heat Exchanger with Circulating Fluidized Beds  

Microsoft Academic Search

Fluidized bed type heat exchangers are known to increase the heat transfer and prevent the fouling. For proper design of circulating fluidized bed heat exchanger it is important to know the effect of design and operating parameters on the bed to the wall heat transfer coefficient. The present experimental and numerical study was conducted to investigate the effects of circulating

Ho Keun Kang; Soo Whan Ahn; Jong Woong Choi; Byung Chang Lee

2010-01-01

267

MODELING OF THE FLOW AND HEAT TRANSFER IN MICRO HEAT PIPES  

Microsoft Academic Search

The fluid flow and heat transfer characteristics of micro heat pipes are analyzed theoretically, in order to understand the physical phenomena and quantify the influence of various parameters on overall thermal performance of these devices. A one-dimensional model is utilized to solve the governing equations for the liquid\\/vapor flow and the heat transfer in the heat pipe channel. Variations in

CHOONDAL B. SOBHAN

268

A STUDY ON THE SOLIDIFICATION HEAT TRANSFER CHARACTERISTICS OF HEAT STORAGE SYSTEM UTILIZING THE PCM  

Microsoft Academic Search

This study is concerned with the solidification heat transfer characteristics of phase change energy storage system. The heat transfer characteristics experiment for the solidification of PCM is performed on the PCM cylindrical heat exchanger with six fins. Experimental results are compared with the theory to investigate the appropriateness of heat conduction equation of PCM and the effect of coolant inlet

WOO SIK KIM; HEE OEUL SONG

1988-01-01

269

Natural convection heat transfer from a heat sink with hollow\\/perforated circular pin fins  

Microsoft Academic Search

Experiments were performed on natural convection heat transfer from circular pin fin heat sinks subject to the influence of its geometry, heat flux and orientation. The geometric dependence of heat dissipation from heat sinks of widely spaced solid and hollow\\/perforated circular pin fins with staggered combination, fitted into a heated base of fixed area is discussed. Over the tested range

E. A. M. Elshafei

2010-01-01

270

Comparison of heat transfer in solar collectors with heat pipe versus flow through absorbers  

SciTech Connect

Analysis of heat transfer in solar collectors with heat pipe absorbers is compared to that for collectors with flow through absorbers. Both pumped and thermosiphon systems that produce hot water or other heated fluids are discussed. In these applications the heat pipe absorber suffers a heat transfer penalty compared with the flow through absorber, but in many cases the penalty can be minimized by proper design at the heat pipe condenser and system manifold. When the solar collector is used to drive an absorption chiller, the heat pipe absorber has better heat transfer characteristics than the flow through absorber.

Hull, J.R.

1985-01-01

271

Comparison of heat transfer in solar collectors with heat pipe versus flow through absorbers  

NASA Astrophysics Data System (ADS)

Analysis of heat transfer in solar collectors with heat pipe absorbers is compared to that for collectors with flow through absorbers. Both pumped and thermosiphon systems that produce hot water or other heated fluids are discussed. In these applications the heat pipe absorber suffers a heat transfer penalty compared with the flow through absorber, but in many cases the penalty can be minimized by proper design at the heat pipe condenser and system manifold. When the solar collector is used to drive an absorption chiller, the heat pipe absorber has better heat transfer characteristics than the flow through absorber.

Hull, J. R.

272

Heat transfer coefficient in serpentine coolant passage for CCDTL  

SciTech Connect

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

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

1998-12-31

273

Heat transfer coefficients for drying in pulsating flows  

SciTech Connect

Pulsating flows generated by a Rijke type combustor are studied for drying of grains and food particles. It is assumed that the velocity fluctuations are the main factor in the enhancement of the drying process. The heat transfer coefficients for drying in vibrating beds are utilized to estimate the heat transfer coefficients of fixed beds in pulsating and permeating flows and are compared to the steady flow heat transfer coefficients obtained for solid porous bodies, after perturbing the main flow. The cases considered are compared to the convective heat transfer coefficients employed in non-pulsating drying.

Fraenkel, S.L. [DEM/UFRJ, Rio de Janeiro (Brazil); Nogueira, L.A.H. [IEM/EFEI, Itajuba, Minas Gerais (Brazil); Carvalho, J.A. Jr.; Costa, F.S. [LCP/INPE, Cachoeira Paulista, Sao Paulo (Brazil)

1998-05-01

274

Packet model of external heat transfer for a fluidized bed  

NASA Astrophysics Data System (ADS)

A modification is proposed for the packet model of external heat transfer of a fluidized bed. The modified model considers heat exchange between the particles and the gas flowing through the packet formed by the particles.

Borodulya, V. A.; Kovenskii, V. I.

1984-11-01

275

Heat transfer in a sodium--potassium heat exchanger (potassium boiler) made of helically-coiled tubes  

Microsoft Academic Search

Results of an experimental study of heat transfer and its crisis for potassium boiling in (stainless-steel or niobium-alloy) tubes heated by electricity or by hot sodium are described. The relationships governing the process are analyzed and expressions are derived for the potassium boiling heat transfer rate, critical heat fluxes, transcritical heat transfer rates and convective heat transfer over the hot

I. T. Aladev; V. I. Petrov; A. I. Rzaev; V. F. Khudyakov

1976-01-01

276

Measurement of heat and moisture exchanger efficiency.  

PubMed

Deciding between a passive heat and moisture exchanger or active humidification depends upon the level of humidification that either will deliver. Published international standards dictate that active humidifiers should deliver a minimum humidity of 33mg.l(-1); however, no such requirement exists, for heat and moisture exchangers. Anaesthetists instead have to rely on information provided by manufacturers, which may not allow comparison of different devices and their clinical effectiveness. I suggest that measurement of humidification efficiency, being the percentage moisture returned and determined by measuring the temperature of the respired gases, should be mandated, and report a modification of the standard method that will allow this to be easily measured. In this study, different types of heat and moisture exchangers for adults, children and patients with a tracheostomy were tested. Adult and paediatric models lost between 6.5mg.l(-1) and 8.5mg.l(-1) moisture (corresponding to an efficiency of around 80%); however, the models designed for patients with a tracheostomy lost between 16mg.l(-1) and 18mg.l(-1) (60% efficiency). I propose that all heat and moisture exchangers should be tested in this manner and percentage efficiency reported to allow an informed choice between different types and models. PMID:24047355

Chandler, M

2013-09-01

277

Efficiency of a Water Heating System  

NSDL National Science Digital Library

Students use a watt meter to measure energy input into a hot plate or hot pot used to heat water. The theoretical amount of energy required to raise the water by the measure temperature change is calculated and compared to the electrical energy input to calculate efficiency.

Office Of Educational Partnerships

278

Boiler efficiency methodology for solar heat applications  

NASA Astrophysics Data System (ADS)

This report contains a summary of boiler efficiency measurements which can be applied to evaluate the performance of steam-generating boilers via both the direct and indirect methods. This methodology was written to assist industries in calculating the boiler efficiency for determining the applicability and value of thermal industrial heat, as part of the efforts of the Solar Thermal Design Assistance Center (STDAC) funded by Sandia National Laboratories. Tables of combustion efficiencies are enclosed as functions of stack temperatures and the amount of carbon dioxide and carbon monoxide in the gas stream.

Maples, D.; Conwell, J. C.; Pacheco, J. E.

1992-08-01

279

Heat transfer characteristics of igniter output plumes  

NASA Astrophysics Data System (ADS)

Seven types of pyrotechnic igniters were each mounted at one end of a closed cylindrical bore hole representative of the center hole in a thermal battery. Measurements of local bore wall temperature, T(sub w), using commercially available, fast response (10 microsec) sheathed chromel-constantan thermocouples allowed calculation of local heat transfer rates, q, and wall heat flows, Q. The principal charge constituents of all these igniters were titanium and potassium perchlorate, while three types also contained barium styphnate as an ignition sensitizer. Igniter closure disc materials included glass-ceramic, glass, metal (plain, scored, with and without capture cone), and kapton/RTV. All igniters produced the lowest values of T(sub w) and q at the beginning of the bore, and, except for the igniter with the kapton/RTV closure disc, these quantities increased with distance along the bore. For igniters containing only titanium/potassium perchlorate, the rates of increase of Q along the bore length, compared with those for T(sub w) and q, were generally lower and more variable. The inclusion of barium styphnate produced rates of change in Q that were essentially constant to the end of the bore. The highest overall average wall temperatures were achieved by two igniter types with metal closure discs and no capture cone. No clear correlation was established between peak bore pressure and maximum wall temperature.

Evans, N. A.; Durand, N. A.

280

Modelling and simulation of unsteady heat transfer for aerospacecraft trajectory optimization  

Microsoft Academic Search

Heat input reduction by optimal trajectory control is considered for the range cruise of a hypersonic flight system propelled by a turbo\\/ram jet engines combination. A mathematical model is developed for describing the unsteady heat transfer through the thermal protection system. This model is coupled to the equations of motion of the vehicle. An efficient optimization technique is applied for

M. Dinkelmann; M. Wchter; G. Sachs

2000-01-01

281

On overall heat transfer coefficient in EOR injection wellbore  

Microsoft Academic Search

Heat losses in oil wells can be very significant, especially when comes to EOR Steam injection wells. the loss of thermal energy through the well completion is unavoidable, However, the knowledge of the amount of heat loss is important and can only done if the value of overall heat transfer coefficient is known. This study aims to calculate theoverall heat

Abdelrahman S. Ibrahim; Kanagaswaran Chitalingam; Mohd Amin Shoushtari

2011-01-01

282

The dependence of boiling heat transfer on the properties and geometric parameters of heat-transfer wall  

Microsoft Academic Search

Analysis of the available data reveals that the parameters of boiling heat transfer depend significantly on the thermophysical\\u000a properties of the heat-transfer wall and its geometric characteristics (roughness and thickness of the wall). However, it\\u000a is still difficult to correctly estimate in full the effect of roughness and thickness of the heat-transfer wall. It is possibly\\u000a because of this that

I. I. Gogonin

2006-01-01

283

Carbon dioxide local heat transfer coefficients during flow boiling in a horizontal circular smooth tube  

Microsoft Academic Search

Carbon dioxide is gaining renewed interest as an environmentally safe refrigerant. In order to improve the energy efficiency of R744 systems, an accurate knowledge of heat transfer coefficients is fundamental.In this paper experimental heat transfer coefficients during flow boiling of R744 in a smooth, horizontal, circular, 6.00mm inner diameter tube are presented. We obtained 217 experimental points in 18 operating

R. Mastrullo; A. W. Mauro; A. Rosato; G. P. Vanoli

2009-01-01

284

The heat transfer coefficients of the heating surface of 300 MWe CFB boiler  

NASA Astrophysics Data System (ADS)

A study of the heat transfer about the heating surface of three commercial 300 MWe CFB boilers was conducted in this work. The heat transfer coefficients of the platen heating surface, the external heat exchanger (EHE) and cyclone separator were calculated according to the relative operation data at different boiler loads. Moreover, the heat transfer coefficient of the waterwall was calculated by heat balance of the hot circuit of the CFB boiler. With the boiler capacity increasing, the heat transfer coefficients of these heating surface increases, and the heat transfer coefficient of the water wall is higher than that of the platen heating surface. The heat transfer coefficient of the EHE is the highest in high boiler load, the heat transfer coefficient of the cyclone separator is the lowest. Because the fired coal is different from the design coal in No.1 boiler, the ash content of the fired coal is much lower than that of the design coal. The heat transfer coefficients which calculated with the operation data are lower than the previous design value and that is the reason why the bed temperature is rather high during the boiler operation in No.1 boiler.

Wu, Haibo; Zhang, Man; Lu, Qinggang; Sun, Yunkai

2012-08-01

285

Analysis of combined conductive-radiative heat transfer in a two-dimensional rectangular enclosure with a gray medium  

Microsoft Academic Search

Combined conductive-radiative heat transfer in a two-dimensional enclosure is considered. The numerical procedure is based on a combination of two previous techniques that have been demonstrated to be successful for a two-dimensional pure radiation problem and a one-dimensional combined conductive-radiative heat transfer problem, respectively. Both temperature profile and heat transfer distributions are generated efficiently and accurately. Numerical data are presented

W. W. Yuen; E. E. Takara

1988-01-01

286

Study on heat transfer of heat exchangers in the Stirling engine - Performance of heat exchangers in the test Stirling engine  

Microsoft Academic Search

The heat transfer performance of the actual heat exchangers obtained from the experimental results of the test Stirling engine is presented. The heater for the test engine has 120 heat transfer tubes that consist of a bare-tube part and a fin-tube part. These tubes are located around the combustion chamber and heated by the combustion gas. The cooler is the

Mitsuo Kanzaka; Makio Iwabuchi

1992-01-01

287

Radiation-conduction heat transfer in fibrous heat-resistant insulation under thermal effect  

Microsoft Academic Search

The conjugate diffusion model of radiation transfer and the approximation of radiant thermal conductivity are used to investigate\\u000a the radiation-conduction heat transfer in a flat layer of fibrous heat-resistant insulation under the effect of fire. The\\u000a results of calculation of the characteristics of unsteady-state heat transfer and of the duration of heat resistance of the\\u000a substrate demonstrate the accuracy of

V. G. Zverev; V. D. Goldin; V. A. Nazarenko

2008-01-01

288

Heat and mass transfer in a paper sheet during drying  

SciTech Connect

Paper and fiber board are dried by threading a continuous wet web around each of a series of 50 to 70 dryer drums. The cylinders are internally heated by condensing steam. Part of a conventional multicylinder dryer section is shown. The dryer felt is a highly porous material whose main purpose is to hold the paper sheet in close contact with the dryer shell to increase the heat transfer between the paper and dryer shell to increase the heat transfer between the paper and dryer and to help prevent shrinkage and deformation of the paper sheet. The sheet moisture content entering the drying section is 150 to 200% (dry basis) and the final moisture content varies from 2 to 9%. Many attempts have been made to analyze the paper drying process both theoretically and experimentally. Most theoretical models contain critical assumptions that considerably simplify the heat and mass transport phenomena within the sheet during drying. Kirk and Iida provide a review of existing paper drying simulation models. Most of the existing models assume variables such as temperature, moisture content, or thermal conductivity remain uniform through the sheet thickness, and that water fluxes are negligible. Furthermore, a majority of the models have been developed for corporate use and the details of the models have remained proprietary. A better understanding of the transport phenomena in the paper sheet is needed to model the heat and mass flow through the paper accurately. A flexible model for the entire drying system could aid in the design and maintenance of dryer systems, overall system efficiency, and improved product quality.

Seyed-Yagoobi, J.; Bell, D.O.; Asensio, M.C. (Texas A and M Univ., College Station (United States))

1992-05-01

289

Maximum heat transfer capability two-phase thermosiphons  

NASA Astrophysics Data System (ADS)

A survey of methods for determining critical heat fluxes accounting for factors affecting the limiting heat transfer capability of closed two-phase thermosiphons, primarily in the evaporator and condenser zones, is presented. It is suggested that, at low filling ratios and low heat flux densities, the heat and mass transfer are controlled by interaction of the countercurrent vapor and liquid flows. Although in general the critical heat flux density is seen to be a function of the evaporator length, thermosiphon diameter, pressure, and the angle of inclination of the thermosiphon. The value of the limiting heat flux density is not affected by the condenser geometry or by the filling ratio.

Pioro, I. L.

1983-02-01

290

Radiative Heat Transfer in Combustion Applications: Parallel Efficiencies of Two Gas Models, Turbulent Radiation Interactions in Particulate Laden Flows, and Coarse Mesh Finite Difference Acceleration for Improved Temporal Accuracy  

NASA Astrophysics Data System (ADS)

We investigate several aspects of the numerical solution of the radiative transfer equation in the context of coal combustion: the parallel efficiency of two commonly-used opacity models, the sensitivity of turbulent radiation interaction (TRI) effects to the presence of coal particulate, and an improvement of the order of temporal convergence using the coarse mesh finite difference (CMFD) method. There are four opacity models commonly employed to evaluate the radiative transfer equation in combustion applications; line-by-line (LBL), multigroup, band, and global. Most of these models have been rigorously evaluated for serial computations of a spectrum of problem types [1]. Studies of these models for parallel computations [2] are limited. We assessed the performance of the Spectral-Line-Based weighted sum of gray gasses (SLW) model, a global method related to K-distribution methods [1], and the LBL model. The LBL model directly interpolates opacity information from large data tables. The LBL model outperforms the SLW model in almost all cases, as suggested by Wang et al. [3]. The SLW model, however, shows superior parallel scaling performance and a decreased sensitivity to load imbalancing, suggesting that for some problems, global methods such as the SLW model, could outperform the LBL model. Turbulent radiation interaction (TRI) effects are associated with the differences in the time scales of the fluid dynamic equations and the radiative transfer equations. Solving on the fluid dynamic time step size produces large changes in the radiation field over the time step. We have modified the statistically homogeneous, non-premixed flame problem of Deshmukh et al. [4] to include coal-type particulate. The addition of low mass loadings of particulate minimally impacts the TRI effects. Observed differences in the TRI effects from variations in the packing fractions and Stokes numbers are difficult to analyze because of the significant effect of variations in problem initialization. The TRI effects are very sensitive to the initialization of the turbulence in the system. The TRI parameters are somewhat sensitive to the treatment of particulate temperature and the particulate optical thickness, and this effect are amplified by increased particulate loading. Monte Carlo radiative heat transfer simulations of time-dependent combustion processes generally involve an explicit evaluation of emission source because of the expense of the transport solver. Recently, Park et al. [5] have applied quasi-diffusion with Monte Carlo in high energy density radiative transfer applications. We employ a Crank-Nicholson temporal integration scheme in conjunction with the coarse mesh finite difference (CMFD) method, in an effort to improve the temporal accuracy of the Monte Carlo solver. Our results show that this CMFD-CN method is an improvement over Monte Carlo with CMFD time-differenced via Backward Euler, and Implicit Monte Carlo [6] (IMC). The increase in accuracy involves very little increase in computational cost, and the figure of merit for the CMFD-CN scheme is greater than IMC.

Cleveland, Mathew A.

291

Influence of heat transfer between turbine and compressor on the performance of small turbochargers  

Microsoft Academic Search

When operating a turbocharger with an engine the turbine transfers a considerable amount of heat to its environment and to the compressor. Therefore the flow processes in the turbine as well as in the compressor are strongly diabatic. The definition and the experimental determination of turbine and compressor efficiency require a clear distinction between adiabatic and diabatic efficiencies since the

M. Rautenberg; M. Malobabic; A. Mobarak

1984-01-01

292

Pulse mitigation and heat transfer enhancement techniques. Volume 3: Liquid sodium heat transfer facility and transient response of sodium heat pipe to pulse forward and reverse heat load  

Microsoft Academic Search

This report presents the description of a liquid sodium heat transfer facility (sodium loop) constructed to support the study of transient response of heat pipes. The facility, consisting of the loop itself, a safety system, and a data acquisition system, can be safely operated over a wide range of temperature and sodium flow rate. The transient response of a heat

L. C. Chow; O. J. Hahn; H. X. Nguyen

1992-01-01

293

Calorimetric measurements of energy transfer efficiency and melting efficiency in CO2 laser beam welding  

NASA Astrophysics Data System (ADS)

The previous calorimetric studies of weld melting efficiency and arc efficiency in the GTAW and PAW processes have naturally led us to speculate as to the magnitude of the efficiencies in the LBW process which to data have also not been adequately investigated. Most welding engineers that have had experience with the LBW process are acutely aware that the metals' absorptivity, the surface finish, and the laser wavelength, all play an important role in affecting the energy transfer efficiency, but the extent of their influence and our understanding of the influence of other process variables is not well understood. In addition, it is widely thought that only the LBW or EBW processes can be selected for applications where thermal damage and distortion from the welding process must be kept to a minimum. For these reasons, we have looked forward to performing these calorimetric experiments since they potentially can answer such important questions as: whether or not the melting efficiency of the LBW process is superior to that obtainable with conventional GTAW and PAW welding processes. This study was prompted by poor production yields on switching device due to cracking of the ceramic header after final closure welding with the CO2 LBW process. This calorimetric study was begun in hopes of determining if allowed variations in production process control variables were responsible for increases in heat input and the resulting thermal stresses. By measuring the net heat input to the workpiece with the calorimeter and by measuring the laser output energy and the weld fusion zone size it was possible to determine the magnitudes of both the energy transfer efficiency and the melting efficiency as well as observe their dependence on the process variables.

Fuerschbach, P. W.

294

Determination of the surface heat-transfer coefficient in CE.  

PubMed

A knowledge of the heat-transfer coefficient, h(s), for the external surface of the capillary or the overall heat coefficient, h(OA), is of great value in predicting the mean increase in temperature of the electrolyte, DeltaT(Mean), during electrokinetic separations. For CE, traditional indirect methods of determining h(s) were time-consuming and tended to overestimate cooling efficiency; a novel method is introduced, which is based on curve-fitting of plots of conductance versus voltage to calculate several important parameters including DeltaT(Mean), h(s), the conductance free of Joule heating effects (G(0)) and the voltage that causes autothermal runaway, V(lim). The new method is superior to previously published methods in that it can be performed more quickly and that it corrects for systematic errors in the measurement of electric current for voltages <5 kV. These errors tended to exaggerate the cooling efficiency of commercial instruments so that the calculated increases in electrolyte temperature were smaller than their actual values. Axially averaged values for h(s) were determined for three different commercial CE instruments ranging from 164 W m(-2) K(-1) for a passively cooled instrument in a drafty environment to 460 W m(-2) K(-1) for a liquid-cooled instrument. PMID:19199294

Hruska, Vlastimil; Evenhuis, Christopher J; Guijt, Rosanne M; Macka, Miroslav; Gas, Bohuslav; Marriott, Philip J; Haddad, Paul R

2009-03-01

295

Heat transfer coefficients for staggered arrays of short pin fins  

Microsoft Academic Search

Short pin fins are often used to increase that heat transfer to the coolant in the trailing edge of a turbine blade. Due primarily to limits of casting technology, it is not possible to manufacture pins of optimum length for heat transfer purposes in the trailing edge region. In many cases the pins are so short that they actually decrease

G. J. Vanfossen

1981-01-01

296

Heat and mass transfer during the coffee drying process  

Microsoft Academic Search

For a better comprehension of heat and mass transfer during the coffee drying process and optimization of the industrial application transport coefficients and coffee properties were determined. Heat transfer coefficients were measured for different air velocities and were found to follow the known dimensionless equations for the flow surrounding a sphere. Thermal conductivities and effective diffusion coefficients were measured as

Katrin Burmester; Rudolf Eggers

2010-01-01

297

Heat transfer to impinging isothermal gas and flame jets  

Microsoft Academic Search

Heat transfer characteristics of single and multiple isothermal turbulent air and flame jets impinging on surfaces are reviewed. Both circular and slot two-dimensional jets are considered, and the effect of crossflow on impingement heat transfer is included. The emphasis is on physical phenomena and not on comparison of published empirical correlations or comparisons of theory and experiments. The review focuses

R. Viskanta

1993-01-01

298

A Reference Model for Ground Coupled Heat Transfer  

Microsoft Academic Search

A recently completed extension to IEA BESTEST includes further work on tests suitable for the validation of ground coupled heat transfer modules within building energy simulation software. The model described here forms part of this work. A finite difference model was prepared and applied to ground coupled heat transfer in the environs of a building for a range of geometries

Michael Crowley

2009-01-01

299

An experimental investigation on heat transfer in rotating coolant channels  

NASA Astrophysics Data System (ADS)

This paper deals with a facility and an experimental technique for researching the heat transfer of coolant channels in the rotating turbine blade, and presents the preliminary results of the convective coefficient of the flow parallel to the axis in the rotating conditions. The results show that the effect of rotating on heat transfer is highly enhanced by centrifugal and Coriolis forces.

Wang, Baoguan; Ding, Xiaojiang

1989-07-01

300

Two Dimensional Finite Element Heat Transfer Models for Softwood  

Microsoft Academic Search

The anisotropy of wood creates a complex problem for solving heat and mass transfer problems that require analyses be based on fundamental material properties of the wood structure. Most heat transfer models use average thermal properties across either the radial or tangential directions and have not differentiated the effects of cellular alignment, earlywood\\/latewood differentiation, ring orientation, and moisture content. Two

Hongmei Gu

301

Heat transfer in rotating cylindrical cells with partitions  

Microsoft Academic Search

A numerical analysis and an experimental study of heat transfer rate in rotating cylindrical cells with partitions are performed. The work is done mainly in the Ekman suction regime, where the Coriolis force dominates over centrifugal buoyancy. It is shown that the heat transfer rate increases substantially by placing partitions in the cell. The partitions suppress the Coriolis force so

Thaveesak Boonpongmanee; Yasuhiro Kamotani

2009-01-01

302

Semiconductor Surface Thermocouples for Determining Heat-Transfer Rates  

Microsoft Academic Search

Possible methods of increasing the sensitivity capabilities for determining heat-transfer rates associated with wind tunnel testing have been investigated. Techniques utilizing surface thermocouples of conventional thermocouple materials do not provide the necessary temperature sensitivity to low heat-transfer rates. This need for increased sensitivity has resulted in development and evaluation of surface thermocouples fabricated from semiconductor materials. Calibration of the semiconductor

David N. Kendall; W. Paul Dixon; Edward H. Schulte

1967-01-01

303

Heat Transfer Design Calculations for Individual Sealed Storage Casks.  

National Technical Information Service (NTIS)

Heat transfer analyses were performed for sealed casks used for the storage of high-level wastes from nuclear power plants. Three kinds of heat transfer calculations were made for individual sealed storage cask units: steady-state analyses during normal o...

H. C. Burkholder

1975-01-01

304

Heat Transfer Analysis for a Fixed CST Column  

Microsoft Academic Search

In support of a small column ion exchange (SCIX) process for the Savannah River Site waste processing program, a transient two-dimensional heat transfer model that includes the conduction process neglecting the convection cooling mechanism inside the crystalline silicotitanate (CST) column has been constructed and heat transfer calculations made for the present design configurations. For this situation, a no process flow

2004-01-01

305

Evaluating convective heat transfer coefficients using neural networks  

Microsoft Academic Search

Liquid crystal thermography combined with transient conduction analysis is often used to deduce local values of convective heat transfer coefficients. Neural networks based on the backpropagation algorithm have been successfully applied to predict heat transfer coefficients from a given set of experimentally obtained conditions. Performance characteristics studied on numerous network configurations relevant to this application indicate that a 3-6-3-1 arrangement

K. Jambunathan; S. L. Hartle; S. Ashforth-Frost; V. N. Fontama

1996-01-01

306

A new model for nucleate boiling heat transfer  

Microsoft Academic Search

A new model to calculate heat transfer coefficients in nucleate boiling is presented. Heat transfer and fluid flow around a single bubble are investigated taking into account the influence of meniscus curvature, adhesion forces and interfacial thermal resistance on the thermodynamic equilibrium at the gas-liquid interface. The model requires only bubble site densities and departure diameters. Further quantities except the

P. Stephan; J. Hammer

1994-01-01

307

Direct numerical simulation of heat transfer over riblets  

Microsoft Academic Search

Riblets are well-known as a passive mean for drag reduction in turbulent flow conditions, but their effectiveness for heat transfer is quite controversial. In this paper we present the numerical results for fully developed laminar and turbulent flow and heat transfer in a channel with triangular riblets. The turbulent study is performed by means of direct numerical simulation at a

E Stalio; E Nobile

2003-01-01

308

Viscoelastic fluids: A new challenge in heat transfer  

Microsoft Academic Search

A review of the current knowledge on the fluid mechanics and heat transfer behavior of viscoelastic aqueous polymer solutions in channel flow is presented. Both turbulent and laminar flow conditions are considered. For fully established turbulent channel flow, it was found that the friction factor, f, and the dimensionless heat transfer factor, j{sub H}, were functions of the Reynolds number

Hartnett

1992-01-01

309

MSG test report-steady-state heat transfer. [LMFBR  

Microsoft Academic Search

This report documents the results of the Steady-State Heat Transfer Tests conducted on the AI Modular Steam Generator (MSG), at the Sodium Component Test Installation (SCTI) of the Liquid Metal Engineering Center. Heat transfer and pressure drop performance data are given along with current predictions of performance. Departure from nucleate boiling characteristics is given. A dispersed flow film boiling model,

Harty

2008-01-01

310

Thermodynamic efficiency of pumped heat electricity storage.  

PubMed

Pumped heat electricity storage (PHES) has been recently suggested as a potential solution to the large-scale energy storage problem. PHES requires neither underground caverns as compressed air energy storage (CAES) nor kilometer-sized water reservoirs like pumped hydrostorage and can therefore be constructed anywhere in the world. However, since no large PHES system exists yet, and theoretical predictions are scarce, the efficiency of such systems is unknown. Here we formulate a simple thermodynamic model that predicts the efficiency of PHES as a function of the temperature of the thermal energy storage at maximum output power. The resulting equation is free of adjustable parameters and nearly as simple as the well-known Carnot formula. Our theory predicts that for storage temperatures above 400?C PHES has a higher efficiency than existing CAES and that PHES can even compete with the efficiencies predicted for advanced-adiabatic CAES. PMID:24074066

Thess, Andr

2013-09-13

311

Thermodynamic Efficiency of Pumped Heat Electricity Storage  

NASA Astrophysics Data System (ADS)

Pumped heat electricity storage (PHES) has been recently suggested as a potential solution to the large-scale energy storage problem. PHES requires neither underground caverns as compressed air energy storage (CAES) nor kilometer-sized water reservoirs like pumped hydrostorage and can therefore be constructed anywhere in the world. However, since no large PHES system exists yet, and theoretical predictions are scarce, the efficiency of such systems is unknown. Here we formulate a simple thermodynamic model that predicts the efficiency of PHES as a function of the temperature of the thermal energy storage at maximum output power. The resulting equation is free of adjustable parameters and nearly as simple as the well-known Carnot formula. Our theory predicts that for storage temperatures above 400C PHES has a higher efficiency than existing CAES and that PHES can even compete with the efficiencies predicted for advanced-adiabatic CAES.

Thess, Andr

2013-09-01

312

Investigation of heat transfer on the Dowthern A gravity assisted heat pipe  

Microsoft Academic Search

An experimental study on heat transfer performance of a gravity-assisted heat pipe is described. Dowtherm A has been used as working fluid. The effect of fill ratio, inclination angle, heat length ratio, and thermal resistance on the rate of heat flow were investigated. Finding a dependence of the maximum rate of heat flow on the first two parameters, a corresponding

C. Wang; D.-Q. Xu; S.-P. Li

1993-01-01

313

Conjugate forced convectionconduction heat transfer analysis of a heat generating vertical cylinder  

Microsoft Academic Search

Conjugate heat transfer by forced convection over a vertical cylinder without heat generation has been a subject of many investigations in the recent past. In the present work, the radial heat conduction along with heat generation in a vertical cylinder is considered for analysis. The steady two-dimensional conduction equation for the heat generating cylinder and steady two-dimensional laminar boundary layer

G Jilani; S Jayaraj; M Adeel Ahmad

2002-01-01

314

Study and Analysis of Heat Transfer Limitation of Separated Heat Pipe  

Microsoft Academic Search

satellite and spacecraft. evaporator, heat isolation and condenser along the axial direction. The working fluid absorbs heat and evaporates in evaporator, and then the vapor flows to condenser and gives out heat. The condensed liquid is pumped to evaporator by wick. By the circulation, the heat can by transferred continuously. heat pipe as follow: - Vapor-liquid two phase flow inside

Qizheng Mou; Kai Mou

2002-01-01

315

Heat transfer in thin, compact heat exchangers with circular, rectangular, or pin-fin flow passages  

Microsoft Academic Search

The authors have measured heat transfer and pressure drop of three thin, compact heat exchangers in helium gas at 3.5 MPa and higher, with Reynolds numbers of 450 to 36,000. The flow geometries for the three heat exchanger specimens were: circular tube, rectangular channel, and staggered pin fin with tapered pins. The specimens were heated radiatively at heat fluxes up

D. A. Olson

1992-01-01

316

Heat transfer effectiveness of three-fluid separated heat pipe exchanger  

NASA Astrophysics Data System (ADS)

A heat transfer model for three-fluid separated heat pipe exchanger was analyzed, and the temperature transfer matrix for general three-fluid separated heat exchanger working in parallel-flow or counter-flow mode was obtained. It was found that the forms of temperature transfer matrix are similar for heat pipe rows with equal or different heat transfer surface area. Furthermore, by using the temperature transfer matrix of the heat pipe exchanger, the relationship between heat transfer effectiveness ? 1, ? 2 and M, NTU, U, ?t i were derived for the exchanger operating in parallel-flow or counter-flow mode, and a simple special example was adopted to demonstrate the correctness of these relationships.

Shi, Chengming; Wang, Yang; Yang, Ying; Liao, Quan

2011-03-01

317

An experimental study on the heat transfer characteristics of a heat pipe heat exchanger with latent heat storage. Part II: Simultaneous charging\\/discharging modes  

Microsoft Academic Search

In this part of the paper, the performance of the simultaneous charging\\/discharging operation modes of the heat pipe heat exchanger with latent heat storage is experimentally studied. The experimental results show that the device may operate under either the fluid to fluid heat transfer with charging heat to the phase change material (PCM) or the fluid to fluid heat transfer

Zhongliang Liu; Zengyi Wang; Chongfang Ma

2006-01-01

318

Phononic heat transfer across an interface: thermal boundary resistance.  

PubMed

We present a general theory of phononic heat transfer between two solids (or a solid and a fluid) in contact at a flat interface. We present simple analytical results which can be used to estimate the heat transfer coefficient (the inverse of which is usually called the 'thermal boundary resistance' or 'Kapitza resistance'). We present numerical results for the heat transfer across solid-solid and solid-liquid He contacts, and between a membrane (graphene) and a solid substrate (amorphous SiO(2)). The latter system involves the heat transfer between weakly coupled systems, and the calculated value of the heat transfer coefficient is in good agreement with the value deduced from experimental data. PMID:21406883

Persson, B N J; Volokitin, A I; Ueba, H

2011-01-07

319

Natural convection heat transfer in passive solar residences  

SciTech Connect

The study of natural convection flows in enclosed spaces is one of the most active subfields of heat transfer research today. Solar energy applications have provided the major stimulus for this research because of the importance of natural convection as a heat transfer mechanism in passive solar buildings and solar collectors. In the present paper we present a review of recent natural convection heat transfer research which has application to passive solar buildings. The review begins with an introduction to the nomenclature used in the heat transfer literature and then reviews natural convection research related to heat transfer through external surfaces, natural convection within a single zone and natural convection between building zones. The review concludes by outlining important research areas in which our present understanding is incomplete.

Anderson, R.

1985-10-01

320

Measuring seasonal efficiency of space heating boilers  

SciTech Connect

Recognition of the importance of energy efficiency has led to the generation of much research information about the energy efficiencies of various HVAC systems. However, intermediate sized space heating boilers have been largely omitted from these research efforts. While previous investigation into modeling and field measurement of the performance of on/off boilers has been conducted, no method for determining in-situ performance has been widely adopted. Accordingly, a research project was undertaken with one main goal being the development of a low cost method for determining the seasonal efficiency of multifamily boilers in-situ. In this project, previously developed models and diagnostic test techniques were refined and validated against direct measurements of the part-load efficiency of three commercial on/off boilers that heat multifamily buildings. This article summarizes the boiler model refinement work and describes how three short-term test techniques are applied. It also describes how well the results of these test techniques compare to direct efficiency measurements.

Landry, R.W.; Lobenstein, M.S.; Bohac, D.L. (Center for Energy and Environment, Minneapolis, MN (United States)); Maddox, D.E. (Weidt Group, Minnetonka, MN (United States))

1993-09-01

321

Reduction of turbulent, flat plate heat transfer with riblets  

NASA Astrophysics Data System (ADS)

Low speed wind tunnel tests were conducted to ascertain the influence of riblets on convective heat-transfer rate in a zero pressure-gradient, incompressible turbulent boundary layer. For reference, smooth flat-plate data were obtained simultaneously with the riblet data; both test walls were heated to a uniform temperature 50 C above the freestream temperature. The riblets were found to reduce turbulent drag by up to 7 percent for spacings below 30 wall units, consistent with previous riblet research. The riblets affected heat transfer in a manner similar to their effect on drag, showing themselves to constitute a promising method for turbulent heat transfer reduction.

Stone, Timothy D.; Guenette, Gerald R.; Epstein, Alan H.

1992-01-01

322

Model investigations of convective heat transfer and pressure loss in diagonal membrane heating surfaces  

NASA Astrophysics Data System (ADS)

The paper presents the results of an investigation concerning heat transfer and pressure loss in air crossflow of diagonally shaped membrane heating surfaces. The heat and mass transfer analogy by means of naphthalene sublimation technique is used in order to evaluate mean Nusselt number values in such tube banks. The effect of tube bank arrangement on heat transfer coefficients and flow resistance is discussed. Convective heat transfer and pressure loss characteristics of diagonally shaped membrane tube banks, plain tube banks and ordinary membrane tube banks are compared.

Pronobis, M.; Kalisz, S.; Wejkowski, R.

323

Thermophysical and heat transfer properties of phase change material candidate for waste heat transportation system  

Microsoft Academic Search

A waste heat transportation systemtrans-heat (TH) systemis quite attractive that uses the latent heat of a phase change\\u000a material (PCM). The purpose of this paper is to study the thermophysical properties of various sugars and sodium acetate trihydrate\\u000a (SAT) as PCMs for a practical TH system and the heat transfer property between PCM selected and heat transfer oil, by using

Akihide Kaizawa; Nobuhiro Maruoka; Atsushi Kawai; Hiroomi Kamano; Tetsuji Jozuka; Takeshi Senda; Tomohiro Akiyama

2008-01-01

324

Heat transfer from pin-fin heat sinks under multiple impinging jets  

Microsoft Academic Search

The enhancement of heat transfer from a discrete heat source using multiple jet impingement of air in a confined arrangement was experimentally investigated. A variety of pin-fin heat sinks were mounted on the heat source and the resulting enhancement studied. Average heat transfer coefficients are presented for a range of jet Reynolds numbers (2000

Hani A. El-Sheikh; Suresh V. Garimella

2000-01-01

325

Enhancement of air jet impingement heat transfer using pin-fin heat sinks  

Microsoft Academic Search

The enhancement of heat transfer from a discrete heat source in confined air jet impingement was experimentally investigated. A variety of pin-fin heat sinks were mounted on the heat source and the resulting enhancement studied, Average heat transfer coefficients are presented for a range of jet Reynolds numbers (8000⩽Re⩽45000) and orifice diameters (12.7⩽d⩽38.1 mm). A total fin effectiveness was computed

Hani A. El-Sheikh; S. V. Gurimella

2000-01-01

326

Using supercritical heat recovery process in Stirling engines for high thermal efficiency  

Microsoft Academic Search

Stirling engine, using a composite working fluid, such as two-component fluid: gaseous carrier and phase-change component and single multi-phase fluid as the working fluid is studied to get high thermal efficiency. In Stirling engine with a composite fluid, a thermodynamic supercritical heat recovery and heating process is proposed and demonstrated to improve the heat transfer of the heat regenerator and

Zhaolin Gu; Haruki Sato; Xiao Feng

2001-01-01

327

Instantaneous heat-transfer area in an evaporating drop  

Microsoft Academic Search

The instantaneous liquid-liquid transfer area in an evaporating two-phase drop is one of the most complex variables in determining the rate of heat transfer in the direct-contact heat exchanger. Attempts have been made by previous workers to predict the instantaneous liquid-liquid transfer area by assuming both a spherical and an ellipsoidal shape for the bubble, with the dispersed phase liquid

D. X. Basu; K. L. Pinder

1978-01-01

328

Analysis of heat transfer in unlooped and looped pulsating heat pipes  

Microsoft Academic Search

An advanced heat transfer model for both unlooped and looped Pulsating Heat Pipes (PHPs) with multiple liquid slugs and vapor plugs has been developed. The thin film evaporation and condensation models have been incorporated with the model to predict the behavior of vapor plugs and liquid slugs in the PHP. The results show that heat transfer in both looped and

M. B. Shafii; A. Faghri; Yuwen Zhang

2002-01-01

329

Study on heat transfer of heat exchangers in the Stirling engine - Performance of heat exchangers in the test Stirling engine  

NASA Astrophysics Data System (ADS)

The heat transfer performance of the actual heat exchangers obtained from the experimental results of the test Stirling engine is presented. The heater for the test engine has 120 heat transfer tubes that consist of a bare-tube part and a fin-tube part. These tubes are located around the combustion chamber and heated by the combustion gas. The cooler is the shell-and-tube-type heat exchanger and is chilled by water. It is shown that the experimental results of heat transfer performance of the heater and cooler of the test Stirling engine are in good agreement with the results calculated by the correlation proposed in our previous heat transfer study under the periodically reversing flow condition. Our correlation is thus confirmed to be applicable to the evaluation of the heat transfer coefficient and the thermal design of the heat exchangers in the Stirling engine.

Kanzaka, Mitsuo; Iwabuchi, Makio

1992-11-01

330

Heat transfer of dilute viscoelastic solutions in helical exchangers  

NASA Astrophysics Data System (ADS)

The study examined heat transfer of two dilute viscoelastic solutions in helical exchangers of circular cross-section. Ten helical coil heat exchangers with diameter ratios ranging from 4 to 50 were constructed. Results showed doubling the concentrations of polymer increased heat transfer performance by 12 %. The results were expressed in forms of some existing equations and were found to be in fair agreement to previous results.

Ismail, Z.; Karim, R.

2013-05-01

331

Natural convection heat transfer from two horizontal cylinders  

SciTech Connect

Natural convection heat transfer from a single horizontal cylinder and a pair of vertically aligned horizontal cylinders is investigated. Surface heat transfer distributions around the circumference of the cylinders are presented for Rayleigh numbers of 2 x 10{sup 6}, 4 x 10{sup 6} and 6 x 10{sup 6} and a range of cylinder spacings of 1.5, 2 and 3 diameters. With a cylinder pairing the lower cylinder is unaffected by the presence of the second cylinder; the same is true of the upper cylinder if the lower one is not heated. However, when both cylinders are heated it has been found that a plume rising from the heated lower cylinder interacts with the upper cylinder and significantly affects the surface heat transfer distribution. Spectral analysis of surface heat transfer signals has established the influence of the plume oscillations on the heat transfer. Thus, when the plume from the lower cylinder oscillates out of phase with the flow around the upper cylinder it increases the mixing and results in enhanced heat transfer. (author)

Reymond, Olivier; Murray, Darina B. [Department of Mechanical and Manufacturing Engineering, Trinity College Dublin (Ireland); O'Donovan, Tadhg S. [School of Engineering and Physical Sciences, Heriot-Watt University, Nasmyth Building, Edinburgh EH14 4AS (United Kingdom)

2008-09-15

332

Heat transfer in open-cell metal foams  

Microsoft Academic Search

The paper explores the use of open-celled metal foams as compact heat exchangers, exploiting convective cooling. An analytical model is developed for model foams with simple cubic unit cells consisting of heated slender cylinders, based on existing heat transfer data on convective crossflow through cylinder banks. A foam-filled channel having constant wall temperatures is analyzed to obtain the temperature distribution

T. J. Lu; H. A. Stone; M. F. Ashby

1998-01-01

333

Cooperative Heat Transfer and Ground Coupled Storage System.  

National Technical Information Service (NTIS)

A cooperative heat transfer and ground coupled storage system wherein collected solar heat energy is ground stored and permitted to radiate into the adjacent ground for storage therein over an extended period of time when such heat energy is seasonally ma...

P. D. Metz

1979-01-01

334

Variation of laser energy transfer efficiency with well pool depth  

SciTech Connect

A series of CO{sub 2} laser welds were made at a constant beam irradiance of 6 MW/cm{sup 2} on 304 stainless steel with travel speeds selected to produce welds with varying levels of weld penetration. Using a Seebeck envelope calorimeter, the net heat input to the part was measured for each weld. It was found that the energy transfer efficiencies varied from 0.29 to 0.86, and decreased at high travel speeds where the weld penetration depth was as shallow as 0.13 mm. The decrease in beam absorption with decreasing weld pool depth is consistent with an absorption mechanism that requires multiple internal reflections within the weld pool. Equations have been developed which conn -ct the keyhole cavity dimensions with the energy transfer efficiency, and correlations with the experimental data have determined the keyhole cavity radius to be 0.1 mm for a focused laser beam with a spot radius of 0.059 mm.

Fuerschbach, P.W.; MacCallum, D.O.

1995-12-01

335

Physical quantity synergy in the field of turbulent heat transfer and its analysis for heat transfer enhancement  

Microsoft Academic Search

Based on the principle of physical quantity synergy in the field of laminar heat transfer, and according to the models of\\u000a zero equation and k-? two equations for the turbulent flow, the synergy equations for both energy and momentum conservation in the turbulent heat\\u000a transfer are established. The synergy regulation among heat flux, mass flow and fluid driving force, and

Wei Liu; ZhiChun Liu; SuYi Huang

2010-01-01

336

Numerical simulation of heat transfer in a gas solid crossflow moving packed bed heat exchanger  

NASA Astrophysics Data System (ADS)

The mechanism of heat transfer in a crossflow moving packed bed heat transfer exchanger is analyzed and a two dimensional heat transfer mathematical model has been developed based on the two fluid model (TFM) approach, in which both phases are considered to be continuous and fully interpenetrating. This model is solved by means of numerical method and the results are approximately in agreement with the experimental ones.

Liu, Anyuan; Liu, Shi; Duan, Yufeng; Pan, Zhonggang

2001-07-01

337

Nanoscale heat transfer and thermoelectrics for alternative energy  

NASA Astrophysics Data System (ADS)

In the area of alternative energy, thermoelectrics have experienced an unprecedented growth in popularity because of their ability to convert waste heat into electricity. Wired in reverse, thermoelectrics can act as refrigeration devices, where they are promising because they are small in size and lightweight, have no moving parts, and have rapid on/off cycles. However, due to their low efficiencies bulk thermoelectrics have historically been a niche market. Only in the last decade has thermoelectric efficiency exceeded 20% due to fabrication of nanostructured materials. Nanoscale materials have this advantage because electronic and acoustic confinement effects can greatly increase thermoelectric efficiency beyond bulk values. In this talk, I will introduce our work in the area of nanoscale heat transfer with the goal of more efficient thermoelectrics. I will discuss our experiments and methods to study acoustic confinement in nanostructures and present some of our new nanostructured thermoelectric materials. To study acoustic confinement we are building a nanoscale phonon spectrometer. The instrument can excite phonon modes in nanostructures in the 100s of GHz. Ballistic phonons from the generator are used to probe acoustic confinement and surface scattering effects. Transmission studies using this device will help optimize materials and morphologies for more efficient nanomaterial-based thermoelectrics. For materials, our group has synthesized nano-layer superlattices of NaxCoO2. Sodium cobaltate was recently discovered to have a high Seebeck coeficent and is being studied as an oxide thermoelectric material. The thickness of our nano-layers ranges from 5 nm to 300 nm while the lengths can be varied between 10 ?m and 4 mm. Typical aspect ratios are 40 nm: 4 mm, or 1:100,000. Thermoelectric characterization of samples with tilted multiple-grains along the measurement axis indicate a thermoelectric efficiency on par with current polycrystalline samples. Due to phonon confinement in nano-structures, it is expected that the thermoelectric efficiency of these sheets will be much higher than that of single crystalline Na0.7CoO2, when the nanosheets have single grains along the heat transport path.

Robinson, Richard

2011-03-01

338

Calculation of heat transfer in a radially rotating coolant passage  

SciTech Connect

The three-dimensional flow field and heat transfer in a radially rotating coolant passage are studied numerically. The passage chosen has a square cross section with smooth isothermal walls of finite length. The axis rotation is normal to the flow direction with the flow radially outward. The effects of Coriolis forces, centrifugal buoyancy, and fluid Reynolds number on the flow and heat transfer have all been considered. The analysis has been performed by using a fully elliptic, three-dimensional, body-fitted computational fluid dynamics code based on pressure correction techniques. The numerical technique employs a multigrid iterative solution procedure and the standard k [minus] [epsilon] turbulence model for both the hydrodynamics and heat transfer. The effect of rotation is included by considering the governing equations of motion in a relative frame of reference that moves with the passage. The consequence of rotation is to bring higher velocity fluid from the core to the trailing surface, thereby increasing both the friction and heat transfer at this face. At the same time, the heat transfer is predicted to decrease along the leading surface. The effect of buoyancy is to increase the radial velocity of the fluid, thus generally increasing the heat transfer along both the leading and trailing surfaces. These effects and trends that have been predicted are in agreement with experimental heat transfer data available in the literature. The quantitative agreement with the data was also found to be quite satisfactory.

Tolpadi, A.K. (General Electric Corporate Research and Development, Schenectady, NY (United States))

1994-12-01

339

High Heat Flux Droplet Impingement Heat Transfer. Phase 1 Final Report.  

National Technical Information Service (NTIS)

The drive toward more densely packaged microelectronics has resulted in a dramatic increase in the amount of waste heat which must be dissipated. The report describes a cooling concept, based on droplet impingement heat transfer, that has the potential to...

J. A. Valenzuela B. C. Drew

1987-01-01

340

Flow and coupled heat transfer in the cavity between the rotor and stator  

NASA Astrophysics Data System (ADS)

The turbulent flow and coupled heat transfer in the cavity between the rotor and stator is numerically simulated. Reynolds-averaged Navier-Stokes equations closed with equations of the k-? turbulence model are used to calculate the viscous compressible gas flow characteristics and heat transfer; the unsteady heat conduction equation is used to calculate the temperature field in the metal. The influence of the mass flow rate of the coolant on the flow structure and efficiency of cooling of the rotor and stator walls is studied. The calculated results are compared with experimental data.

Volkov, K. N.

2011-05-01

341

Specific Investment Under Negotiated Transfer Pricing: An Efficiency Result  

Microsoft Academic Search

In our model of negotiated transfer pricing, divisional managers can make specific investments that enhance the value of intrafirm trade. However, these investments are irreversible and must be made before divisional managers have enough information to determine the desired intrafirm transfer. We find that a system of negotiated transfer pricing will lead to efficient outcomes provided the divisions can sign

Aaron S. Edlin; Stefan J. Reichelstein

1995-01-01

342

Increasing the Efficiency of Maple Sap Evaporators with Heat Exchangers.  

National Technical Information Service (NTIS)

A study of the engineering and economic effects of heat exchangers in conventional maple syrup evaporators indicated that: (1) Efficiency was increased by 15 to 17 percent with heat exchangers; (2) Syrup produced in evaporators with heat exchangers was si...

L. D. Garrett H. Duchacek M. Morselli F. M. Laing N. K. Huyler

1977-01-01

343

Convective heat transfer in buildings: Recent research results  

NASA Astrophysics Data System (ADS)

Small scale water filled enclosures were used to study convective heat transfer in buildings. The convective processes investigated are: (1) natural convective heat transfer between room surfaces and the adjacent air; (2) natural convective heat transfer between adjacent rooms through a doorway or other openings; and (3) forced convection between the building and its external environment (such as, wind driven ventilation through windows, doors, or other openings). Results for surface convection coefficients are compared with existing ASHRAE coorelations and differences of as much as 20% are observed. Numerical simulations of wind driven natural ventilation exhibit good qualitative agreement with published wind tunnel data.

Bauman, F. S.; Gadgil, A.; Kammerud, R. C.; Altmayer, E.; Nansteel, M.

1982-04-01

344

Transition modeling effects on turbine rotor blade heat transfer predictions  

SciTech Connect

The effect of transition modeling on the heat transfer predictions from rotating turbine blades was investigated. Three-dimensional computations using a Reynolds-averaged Navier-Stokes code were performed. The code utilized the Baldwin-Lomax algebraic turbulence model, which was supplemented with a simple algebraic model for transition. The heat transfer results obtained on the blade surface and the hub endwall were compared with experimental data for two Reynolds numbers and their corresponding rotational speeds. The prediction of heat transfer on the blade surfaces was found to improve with the inclusion of the transition length model and wake-induced transition effects over the simple abrupt transition model.

Ameri, A.A. [Univ. of Kansas Center for Research Inc., Lawrence, KS (United States); Arnone, A. [Univ. of Florence (Italy). Dept. of Energy Engineering

1996-04-01

345

Flow of and heat transfer in turbulent slurries  

SciTech Connect

In this paper, flow of and heat transfer in turbulent slurries having a yield stress are discussed. A Bingham plastic model is used to describe their rheological properties. A universal velocity distribution for turbulent flow of the Bingham plastic fluid is derived. The velocity distributions obtained using Prandtl's mixing length theory are in satisfactory agreement with the available data for Bingham plastic fluids in pipes. On the basis of them, a theoretical correlation for heat transfer in turbulent Bingham plastic fluids flowing pipes is obtained. It indicates that a yield stress will decrease the heat transfer rate. The proposed correlation fits the experimental data for fully developed turbulent pipe flows adequately.

Kawase, Y. (Dept. of Applied Chemistry, Toyo Univ., Kawagoe, Saitama 350 (JP)); Moo-Young, M. (Dept. of Chemical Engineering, Univ. of Waterloo, Waterloo, Ontario N2L 3G1 (CA))

1992-07-01

346

Heat transfer during heat sterilization and cooling processes of canned products  

NASA Astrophysics Data System (ADS)

In this paper, an analysis of transient heat transfer during heat sterilization and cooling processes of a cylindrical canned product is presented. In the analysis, most practical case including the boundary condition of third kind (i.e., convection boundary condition, leading to 0.1 <= Bi <= 100) was employed. A simple analytical model for determining effective heat transfer coefficients for such products is developed. For the heat sterilization process, heating coefficient is incorporated into heat transfer coefficient model. An experimental study was performed to measure the thermal center temperatures of the short-cylindrical canned products (i.e., Tuna fish) during heat sterilization at the retort medium temperatures of 115?C and 121?C, and during cooling process at 16?C. The effective heat transfer coefficient model used the experimental temperature data. Using these effective heat transfer coefficients the center temperature distributions were calculated and compared with the experimental temperature distributions. Agreement was found considerably high. The results of the present study indicate that the heat-transfer analysis technique and heat-transfer coefficient model are reliable, and can provide accurate results for such problems.

Dincer, I.

347

Flow Boiling Heat Transfer to a Dielectric Coolant in a Microchannel Heat Sink  

Microsoft Academic Search

This paper presents an experimental study of flow boiling heat transfer in a microchannel heat sink. The dielectric fluid Fluorinert FC-77 is used as the boiling liquid after it is fully degassed. The experiments were performed at three flow rates ranging from 30-50ml\\/min. The heat transfer coefficients, as well as the critical heat flux (CHF), were found to increase with

Tailian Chen; Suresh V. Garimella

2007-01-01

348

Boiling heat transfer in a hydrofoil-based micro pin fin heat sink  

Microsoft Academic Search

Flow boiling of R-123 in a hydrofoil-based micro pin fin heat sink was investigated. Average two-phase heat transfer coefficients were obtained over effective heat fluxes ranging from 19 to 312W\\/cm2 and mass fluxes from 976 to 2349kg\\/m2s. The paper presents a flow map, which divides the data into three flow pattern regions: bubbly, wavy intermittent and spray-annular flows. Heat transfer

Ali Ko?ar; Yoav Peles

2007-01-01

349

Air-side flow and heat transfer in compact heat exchangers: A discussion of enhancement mechanisms  

SciTech Connect

The behavior of air flows in complex heat exchanger passages is reviewed with a focus on the heat transfer effects of boundary-layer development, turbulence, spanwise and streamwise vortices, and wake management. Each of these flow features is discussed for the plain, wavy, and interrupted passages found in contemporary compact heat exchanger designs. Results from the literature are used to help explain the role of these mechanisms in heat transfer enhancement strategies.

Jacobi, A.M. [Univ. of Illinois, Urbana, IL (United States). Dept. of Mechanical and Industrial Engineering; Shah, R.K. [Delphi Harrison Thermal Systems, Lockport, NY (United States)

1998-10-01

350

Investigation on heat transfer characteristics of tapered cylinder pin fin heat sinks  

Microsoft Academic Search

In the present study, experimental and numerical results of the heat transfer characteristics of the in line and staggered taper pin fin heat sink under constant heat flux conditions are presented. An experimental apparatus is set up to analyze the problem. The tapered pin fin heat sink is fabricated from square aluminium with length, base and tip diameters of 67,

Paisarn Naphon; Anusorn Sookkasem

2007-01-01

351

Modeling of Spacer Influence on Post-Dryout Heat Transfer in Heated Channels  

SciTech Connect

Post-dryout heat transfer plays an important role in safe and economical operations of Light Water Reactors (LWR). This type of heat transfer is avoided under normal operational conditions of nuclear reactors; however, it may occur in transient or accidental situations. To estimate the risk of clad damages due to increase of temperature associated with the occurrence of post-dryout, it is necessary to properly model heat transfer processes under such conditions. The influence of various parameters on heat transfer downstream of spacer has been investigated. It is concluded that heat transfer enhancement due to spacers is largely under-predicted for flows with relatively low quality. For such flows the effect of droplets impinging heated walls is significant and must properly be taken into account. The phenomenological model presented in this paper shows a superior accuracy over correlations and presents a potential to capture the phenomenon of rewetting that occurs downstream of spacers. (author)

Anglart, Henryk [Royal Institute of Technology, SE - 100 44, Stockholm (Sweden)

2006-07-01

352

Transient Heat Transfer in TCAP Coils  

SciTech Connect

The Thermal Cycling Absorption Process (TCAP) is used to separate isotopes of hydrogen. TCAP involves passing a stream of mixed hydrogen isotopes through palladium deposited on kieselguhr (Pd/k) while cycling the temperature of the Pd/k. Kieselguhr is a silica mineral also called diatomite. To aid in the design of a full scale facility, the Thermal Fluids Laboratory was used by the Chemical and Hydrogen Technology Section to compare the heat transfer properties of three different configurations of stainless steel coils containing kieselguhr and helium. Testing of coils containing Pd/k and hydrogen isotopes would have been more prototypical but would have been too expensive. Three stainless steel coils filled with kieselguhr were tested; one made from 2.0 inch diameter tubing, one made from 2.0 inch diameter tubing with foam copper embedded in the kieselguhr and one made from 1.25 inch diameter tubing. It was known prior to testing that increasing the tubing diameter from 1.25 inch to 2.0 inch would slow the rate of temperature change. The primary purpose of the testing was to measure to what extent the presence of copper foam in a 2.0" tubing coil would compensate for the effect of larger diameter. Each coil was connected to a pressure gage and the coil was evacuated and backfilled with helium gas. Helium was used instead of a mixture of hydrogen isotopes for reasons of safety. Each coil was quickly immersed in a stirred bath of ethylene glycol at a temperature of approximately 100 degrees Celsius. The coil pressure increased, reflecting the increase in average temperature of its contents. The pressure transient was recored as a function of time after immersion. Because of the actual process will use Pd/k instead of kieselguhr, additional tests were run to determine the differences in thermal properties between the two materials. The method was to position a thermocouple at the center of a hollow sphere and pack the sphere with Pd/k. The sphere was sealed, quickly submerged in a bath of boiling water and the temperature transient was recorded. There sphere was then opened, the Pd/k was replaced with kieselguhr and the transient was repeated. The response was a factor of 1.4 faster for Pd/k than for kieselguhr, implying a thermal diffusivity approximately 40 percent higher than for kieselguhr. Another implication is that the transient tests with the coils would have proceeded faster if the coils had been filled with Pd/k rather than kieselguhr.

Steimke, J.L.

1999-03-09

353

Transient Heat Transfer in TCAP Coils  

SciTech Connect

The Thermal Cycling Absorption Process (TCAP) is used to separate isotopes of hydrogen. TCAP involves passing a stream of mixed hydrogen isotopes through palladium deposited on kieselguhr (Pd/k) while cycling the temperature of the Pd/k. Kieselguhr is a silica mineral also called diatomite. To aid in the design of a full scale facility, the Thermal Fluids Laboratory was used by the Chemical and Hydrogen Technology Section to compare the heat transfer properties of three different configurations of stainless steel coils containing kieselguhr and helium. Testing of coils containing Pd/k and hydrogen isotopes would have been more prototypical but would have been too expensive. Three stainless steel coils filled with kieselguhr were tested; one made from 2.0 inch diameter tubing, one made from 2.0 inch diameter tubing with foam copper embedded in the kieselguhr and one made from 1.25 inch diameter tubing. It was known prior to testing that increasing the tubing diameter from 1.25 inch to 2.0 inch would slow the rate of temperature change. The primary purpose of the testing was to measure to what extent the presence of copper foam in a 2.0 tubing coil would compensate for the effect of larger diameter. Each coil was connected to a pressure gage and the coil was evacuated and backfilled with helium gas. Helium was used instead of a mixture of hydrogen isotopes for reasons of safety. Each coil was quickly immersed in a stirred bath of ethylene glycol at a temperature of approximately 100 degrees Celsius. The coil pressure increased, reflecting the increase in average temperature of its contents. The pressure transient was recored as a function of time after immersion. Because of the actual process will use Pd/k instead of kieselguhr, additional tests were run to determine the differences in thermal properties between the two materials. The method was to position a thermocouple at the center of a hollow sphere and pack the sphere with Pd/k. The sphere was sealed, quickly submerged in a bath of boiling water and the temperature transient was recorded. There sphere was then opened, the Pd/k was replaced with kieselguhr and the transient was repeated. The response was a factor of 1.4 faster for Pd/k than for kieselguhr, implying a thermal diffusivity approximately 40 percent higher than for kieselguhr. Another implication is that the transient tests with the coils would have proceeded faster if the coils had been filled with Pd/k rather than kieselguhr.

Steimke, J.L.

1999-03-09

354

Study of heat and mass transfer in a vertical-tube evaporative cooler  

NASA Astrophysics Data System (ADS)

Evaporative coolers are three-fluid heat exchangers employed for heat rejection to the environment. A mixture of air and recirculating water is used as the cooling medium. These coolers are considered viable routes for improving thermal efficiencies of power-generating and refrigeration cycles. The heat- and mass-transfer processes taking place in a vertical-tube evaporative cooler are studied. A steady-state, one dimensional model of cooler performance is formulated. This model is validated by experimental measurements, taken in a single-tube exchanger, of the controlling heat- and mass-transfer coefficients. These coefficients occur at the air-water interface. Heat fluxes and enhancement ratios for conditions of interest are measured and calculated, and the results are compared and discussed. The model is found to adequately predict heat-exchanger performance.

Perez-Blanco, H.; Bird, W. A.

1982-11-01

355

Theoretical Design of a Thermosyphon for Efficient Process Heat Removal from Next Generation Nuclear Plant (NGNP) for Production of Hydrogen  

SciTech Connect

The work reported here is the preliminary analysis of two-phase Thermosyphon heat transfer performance with various alkali metals. Thermosyphon is a device for transporting heat from one point to another with quite extraordinary properties. Heat transport occurs via evaporation and condensation, and the heat transport fluid is re-circulated by gravitational force. With this mode of heat transfer, the thermosyphon has the capability to transport heat at high rates over appreciable distances, virtually isothermally and without any requirement for external pumping devices. For process heat, intermediate heat exchangers (IHX) are required to transfer heat from the NGNP to the hydrogen plant in the most efficient way possible. The production of power at higher efficiency using Brayton Cycle, and hydrogen production requires both heat at higher temperatures (up to 1000oC) and high effectiveness compact heat exchangers to transfer heat to either the power or process cycle. The purpose for selecting a compact heat exchanger is to maximize the heat transfer surface area per volume of heat exchanger; this has the benefit of reducing heat exchanger size and heat losses. The IHX design requirements are governed by the allowable temperature drop between the outlet of the NGNP (900oC, based on the current capabilities of NGNP), and the temperatures in the hydrogen production plant. Spiral Heat Exchangers (SHEs) have superior heat transfer characteristics, and are less susceptible to fouling. Further, heat losses to surroundings are minimized because of its compact configuration. SHEs have never been examined for phase-change heat transfer applications. The research presented provides useful information for thermosyphon design and Spiral Heat Exchanger.

Piyush Sabharwall; Fred Gunnerson; Akira Tokuhiro; Vivek Utgiker; Kevan Weaver; Steven Sherman

2007-10-01

356

Numerical Study of Heat Transfer From Pin-Fin Heat Sink Using Steady and Pulsated Impinging Jets  

Microsoft Academic Search

This paper investigates numerically the heat transfer characteristics of confined slot jet impingement on a pin-fin heat sink. A variety of pin-fin heat sinks is investigated, and the resulting enhancement of heat transfer studied. The distribution of heat transfer coefficient on the top surface of the base plate and that along the fin height are examined. Both steady and pulsated

Anuradha Sanyal; Kandadai Srinivasan; Pradip Dutta

2009-01-01

357

Compression of the Radiative Heat Transfer BEM Matrix of an Inductive Heating System Using a Block-Oriented Wavelet Transform  

Microsoft Academic Search

Inductive heating processes become more and more important, and therefore the interest in thermal effects of an inductive heating system increases. Radiative heat transfers are normally neglected even though these transfers affect the temperature of the inductive heating system up to ten percent. To compute radiative heat transfers a boundary element method (BEM) is of first choice, due to a

Christian Scheiblich; Vassilios Kolitsas; Wolfgang M. Rucker

2009-01-01

358

Investigation of local heat transfer coefficients in plate heat exchangers with temperature oscillation IR thermography and CFD  

Microsoft Academic Search

A method for the measurement of local convective heat transfer coefficients from the outside of a heat-transferring wall has been developed. This method is contact-free and fluid independent, employing radiant heating by laser or halogen spotlights and an IR camera for surface temperature measurements; it allows for the rapid evaluation of the heat transfer coefficient distribution of sizable heat exchanger

S. Freund; S. Kabelac

2010-01-01

359

Dual-Circuit Embossed-Sheet Heat-Transfer Panel.  

National Technical Information Service (NTIS)

A heat transfer panel provides redundant cooling for fusion reactors or the like environment requiring low-mass construction. Redundant cooling is provided by two independent cooling circuits, each circuit consisting of a series of channels joined to inle...

G. D. Morgan

1982-01-01

360

Boiling heat transfer enhancement of magnetically actuated nanofluids  

NASA Astrophysics Data System (ADS)

Nanofluids offer a potential breakthrough as next-generation heat transfer fluids since they offer exciting new possibilities to enhance heat transfer performance compared to pure liquids. A major drawback for using nanofluids in practical applications is difficulty in maintaining their stability due to deposition on surfaces. In this study, we propose and experimentally investigate a magnetic actuation scheme to avoid this deposition. Two-phase heat transfer characteristics of the designed system have been experimentally investigated with magnetic actuation and compared to the results without magnetic actuation. Two phase average heat transfer enhancement observed with the suggested system was 17%. The average single phase enhancement is found as 29% with magnetic actuation. It was observed that magnetically actuated nanoparticles neither form any clusters nor precipitate after the experiments.

?e?en, Muhsincan; Tek?en, Yi?it; ?ahin, Berna; ?endur, Kr?at; P?nar Meng, M.; Ko?ar, Ali

2013-04-01

361

Heat transfer during condensation in vertical closed thermosiphons  

NASA Astrophysics Data System (ADS)

The results are presented of an experimental investigation of the hydrodynamic characteristics of a two-phase layer and of the heat-transfer behavior under characteristic operating conditions of the condensing section of a thermosiphon.

Bezrodnyi, M. K.; Moklyak, V. F.

1986-07-01

362

7 CFR 3201.54 - Heat transfer fluids.  

Code of Federal Regulations, 2013 CFR

...Products with high thermal capacities used to facilitate the transfer of heat from one location to another, including coolants or refrigerants for use in HVAC applications, internal combustion engines, personal cooling devices, thermal energy storage, or...

2013-01-01

363

Experimental Study on Heat Transfer in an Open Thermosyphon  

NASA Astrophysics Data System (ADS)

Heat transfer coefficient in an open thermosyphon is very small, because the flow in the thermosyphon is confined to a narrow space by the wall of tube with a closed bottom end. Therefore, augmentation of heat transfer due to air injection from the bottom has been suggested. The heat transfer is enhanced by the stirring action of rising bubbles. In response to this, the authors performed an experimental investigation of this subject. Seven test tubes with different diameter and length were employed, and water, ethyl alcohol and ethylene glycol were used as test liquids. The heat transfer coefficients were measured and the effects of air injection rate, tube diameter, tube length and liquid properties were examined. And experimental correlations were presented by using dimensional analysis.

Imura, Hideaki; Kozai, Hiroaki

364

Three-Dimensional Modeling of Heat Transfer from Slab Floors.  

National Technical Information Service (NTIS)

Earth-coupled heat transfer processes have been recognized in recent years as a potential source of significant energy savings in both conventional and earth-sheltered designs, Because of the complexity of the building/soil/atmosphere interaction, however...

W. P. Bahnfleth

1989-01-01

365

Conjugate heat transfer on a non-isothermal rotating disc  

NASA Astrophysics Data System (ADS)

A derivation of the conjugation criterion for a rotating disc is reported. Characteristics of conjugate heat transfer on a single disc and in a cavity formed by two discs, one rotating and the other stationary, are analysed.

Mironova, M. V.; Kortikov, N. N.

2011-12-01

366

Measurement of heat transfer coefficients by nuclear magnetic resonance.  

PubMed

We demonstrate an experimental method for the measurement of heat transfer coefficient for a fluid system by magnetic resonance imaging. In this method, the temporal variation of thermally induced nuclear shielding is monitored and the average heat transfer coefficient is measured as a function of fluid velocity. We examine the cases of natural convection and forced convection at fluid velocity up to 0.8 m s(-1). These cases correspond to low dimensionless Biot (Bi) number where the heat transfer is limited by thermal convection. We demonstrate the NMR method for two simple geometries, a cylinder and a sphere, to experimentally determine the heat transfer coefficient (h) in two NMR imaging and spectroscopy systems through measuring three NMR parameters, the chemical shift, magnetization and spin self diffusion coefficient. PMID:18524523

Gultekin, David H; Gore, John C

2008-06-03

367

Convective Heat Transfer in Buildings: Recent Research Results.  

National Technical Information Service (NTIS)

Recent experimental and numerical studies of convective heat transfer in buildings are described and important results are presented. The experimental work has been performed on small-scale water filled enclosures: the numerical analysis results have been...

F. Bauman A. Gadgil R. Kammerud E. Altmayer M. Nansteel

1982-01-01

368

Convective Heat Transfer in Buildings: Recent Research Results. Rev.  

National Technical Information Service (NTIS)

Recent experimental and numerical studies of convective heat transfer in buildings are described, and important results are presented. The experimental work has been performed on small-scale, water-filled enclosures; the numerical analysis results have be...

F. Bauman A. Gadgil R. Kammerud E. Altmayer M. W. Nansteel

1982-01-01

369

Two-Equation Thermal Model for Heat Transfer Predictions.  

National Technical Information Service (NTIS)

The very high temperature level reached in actual turbine components requires accurate simulation tools to predict the heat transfers. The turbine flow is very complex. it is dominated by high pressure gradients, three- dimensional viscous effects, and hi...

P. Kulisa N. Marciniak

2003-01-01

370

Rotating Plug Model of Friction Stir Welding Heat Transfer.  

National Technical Information Service (NTIS)

A simplified rotating plug model is employed to study the heat transfer phenomena associated with the fiction stir welding process. An approximate analytical solution is obtained based on this idealized model and used both to demonstrate the qualitative i...

A. C. Nunes G. R. Buchanan J. Peddieson

2006-01-01

371

Two Mapping Techniques for Calculating Radiative Heat Transfer with Scattering.  

National Technical Information Service (NTIS)

The problem of radiative heat transfer through a gray, emitting, absorbing, and scattering medium with uniform optical properties is reduced to one without scattering through two techniques. One uses scaling laws, and the other uses a self-consistent effe...

W. C. A. Gu K. K. Murata

1989-01-01

372

The new limit of heat transfer under extreme strain  

NASA Astrophysics Data System (ADS)

Theoretical works have predicted that the thermal conductance of a deformed 1D system will start to decrease when the radius of curvature (Rc) is comparable to the phonon mean free path (l). However, due to limited mechanical strengths and short phonon mean free paths of most materials, no experimental works are capable of testing this fundamental limit of heat transfer so far. Here we utilize the superior mechanical strength and the high thermal conductivity of single-wall carbon nanotubes (SWCNTs) to investigate the heat transfer phenomena at previously inaccessible experimental regime. Surprisingly, the thermal conductivity of SWCNTs remains intact under cyclic strains and the ultimate condition of l/Rc > 10. Moreover, the robustness of heat transfer is found to be independent of defects, dislocations, structural kinks, bent angles, or bent curvatures. Our results demonstrate that SWCNTs are exceptional 1D thermal conductors with capabilities of going beyond the fundamental limit of heat transfer under extreme strain.

Lee, Victor; Chen, Renkun; Chang, Chih-Wei

2012-12-01

373

Heat-transfer characteristics of two-phase thermosiphon heat pipe. Part 1: Boiling heat-transfer correlation in heating section  

Microsoft Academic Search

A correlation for the boiling heat-transfer coefficient in the heating section of a two-phase thermosiphon heat pipe is developed in comparison with experimental data. The experiments were conducted for a vertically oriented thermosiphon pipe using three kinds of working fluid, water, Freon R-113, and ethanol, over a wide pressure range of 0.1 to 20 bar and a fill charge rate

Fumito Kaminaga; Yoshizo Okamoto

1994-01-01

374

Nonlinear aspects of high heat flux nucleate boiling heat transfer. Part 1, Formulation  

SciTech Connect

This paper outlines the essential details of the formulation and numerical implementation of a model used to study nonlinear aspects of the macrolayer-controlled heat transfer process associated with high heat flux nucleate boiling and the critical heat flux. The model addresses the three-dimensional transient conduction heat transfer process within the problem domain comprised of the macrolayer and heater. Heat dissipation from the heater is modeled as the sum of transient transport into the macrolayer, and the heat loss resulting from evaporation of menisci associated with vapor stems.

Sadasivan, P.; Unal, C.; Nelson, R.

1994-04-01

375

Experimental study on heat transfer and flow resistance in improved latticework cooling channels  

NASA Astrophysics Data System (ADS)

Characteristics of heat transfer and flow resistance of the latticework (vortex) cooling channel with ribs truncated at their two ends were theoretically and experimentally studied compared with regular and smooth channels of the same configuration. The results showed: the heat transfer efficiency of the latticework channel with two slots was better than those of regular and smooth channels of the same configuration, its flow resistance situation in the slotted channel becomes quite complex; The flow resistances of 2 mm- and 4 mm-slotted channels were obviously lower than that of the regular channel, but they are still much higher than that of the smooth channel; Compared with the regular channel, the total heat transfer efficiencies of the slotted channels were pretty improved, among them the 4-mm slotted channel has the biggest enhancement. From the experimental results, it is obvious that the latticework channel with proper slots has a great prospect in the design of the inner cooling channels of turbine blades.

Deng, Hongwu; Wang, Kai; Zhu, Jianqin; Pan, Wenyan

2013-06-01

376

Particle-water heat transfer during explosive volcanic eruptions  

NASA Astrophysics Data System (ADS)

Thermal interaction between volcanic particles and water during explosive eruptions has been quantified using a numerical heat transfer model for spherical particles. The model couples intraparticle conduction with heat transfer from the particle surface by boiling water in order to explore heat loss with time for a range of particle diameters. The results are combined with estimates of particle settling times to provide insight into heat removal during eruption from samples of volcanic particles produced by explosive eruption. Heat removal is restricted by resistance to heat transfer from the volcanic particles with intraparticle thermal conduction important for large particles and surface cooling by boiling dominating for small particles. In most cases, volcanic particles approach thermal equilibrium with the surrounding fluid during an explosive eruption. Application of the results to a sample from the Gjlp 1996, Iceland eruption indicates that, relative to 0?C, 70-80% of the heat is transferred from the particles to boiling water during the settling time before burial in the stratigraphic succession. The implication is that, for subglacial explosive eruptions, much of the heat content of the magma is coupled into melting ice extremely rapidly. If all particles of the Gjlp 1996 deposit were cooled to the local boiling point by the end of the eruption then approximately 78% of the initial heat content was removed from the erupting magma during the eruption. This is consistent with calorimetric calculations based on volumes of ice melted during and after the eruption.

Woodcock, D. C.; Gilbert, J. S.; Lane, S. J.

2012-10-01

377

Heat transfer correlations for open-cellular porous materials  

Microsoft Academic Search

A general correlation for volumetric heat transfer coefficient between stream of air and open-cellular porous materials was derived utilizing experimental data obtained by several researchers. The derived correlation is written in form of hv=(A\\/Ds2?n)un. Here, hv denotes the volumetric heat transfer coefficient, A is the constant, n is the velocity exponent, u is the mean fluid velocity and Ds is

Kouichi Kamiuto; San San Yee

2005-01-01

378

FATIGUE AND HEAT TRANSFER BEHAVIOUR OF SHOT ?El\\  

Microsoft Academic Search

In the present investigation glass beads and zirconium oxide shots were used as media, to shot peen alluminium alloy specimens. Fatigue and boiling heat transfer behaviour of this alloy after . shot peenir-fg was studied. Out of 0.2N and 0.4N peening intensities, 0.4N gave higher improvement on fatigue strength and boiling heat transfer. Fatigue of butt welded aluminium joints were

V. S. Nadkarni

379

Viscoelastic fluids: A new challenge in heat transfer  

SciTech Connect

A review of the current knowledge on the fluid mechanics and heat transfer behavior of viscoelastic aqueous polymer solutions in channel flow is presented. Both turbulent and laminar flow conditions are considered. For fully established turbulent channel flow, it was found that the friction factor, f, and the dimensionless heat transfer factor, j{sub H}, were functions of the Reynolds number and a dimensionless elasticity value, the Weissenberg number. For Weissenberg values greater than approximately 10 (the critical value) the friction factor was found to be a function only of the Reynolds number; for values less than 10 the friction factor was a function of both Re and Ws. For the dimensionless heat transfer coefficient j{sub H} the corresponding critical Weissenberg value was found to be about 100. The heat transfer reduction is always greater than the friction factor reduction; consequently, the heat transfer per unit pumping power decreases with increasing elasticity. For fully established laminar pipe flow of aqueous polymer solutions, the measured values of the friction factor and dimensionless heat transfer coefficient were in excellent agreement with the values predicted for a power law fluid. For laminar flow in a 2:1 rectangular channel the fully developed friction factor measurements were in agreement with the power law prediction. In contrast, the measured local heat transfer coefficients for aqueous polymer solutions in laminar flow through the 2:1 rectangular duct were two or three times the values predicted for a purely viscous power law fluid. It is hypothesized that these high heat transfer coefficients are due to secondary motions, which come about as a results of the unequal normal stresses occurring in viscoelastic fluids. The anomalous behavior of one particular aqueous polymer solution-namely, polyacrylic acid (Carbopol)-is described in some detail, raising some interesting questions as to how viscoelastic fluids should be classified.

Hartnett, J.P. (Univ. of Illinois, Chicago (United States))

1992-05-01

380

Measurement of surface heat transfer due to particle impact  

Microsoft Academic Search

Heat transfer coefficients for a surface continuously impacted by a stream of falling particles in air and in helium were measured as functions of particle flux and particle velocity. The purpose was to provide well-controlled data to clarify the mechanisms of heat transfer in particle suspension flows. The particles were spherical glass beads with mean diameters of 0.5, 1.13, and

J. G. Sun; M. M. Chen

1995-01-01

381

Heat transfer in the hot rolling of metals  

Microsoft Academic Search

The heat-transfer coefficient (HTC) in the roll gap during the hot rolling of AA5XXX-series (aluminum-magnesium) alloys has\\u000a been measured in a laboratory mill with the aid of thermocouples attached to the surface and embedded in the interior of test\\u000a samples. The heat-transfer coefficient was calculated from the sample temperature response using an implicit finite-difference\\u000a model over a range of temperatures,

C. O. Hlady; J. K. Brimacombe; I. V. Samarasekera; E. B. Hawbolt

1995-01-01

382

Heat transfer in rotating narrow rectangular pin-fin ducts  

Microsoft Academic Search

Rotational effects on heat transfer in radial-outflow ducts have implications for the design of gas turbine blades. The turbine blade trailing edge convective cavity generally has a narrow cross-section and often utilizes pin-fins for heat transfer enhancement. Previous research on rotational effects considered cavity shapes quite different from those of typical trailing edge cavities. In this research, experiments were conducted

Fred T Willett; Arthur E Bergles

2002-01-01

383

Interface heat transfer in investment casting of aluminum alloys  

Microsoft Academic Search

Via design of experiments and using a newly developed inverse method, the heat-transfer boundary conditions in the investment\\u000a casting process have been studied. It has been shown in the past that these conditions, expressed as interface heat transfer\\u000a coefficients (HTCs), vary during alloy solidification and cooling. In this work, the authors have studied the additional effects\\u000a of alloy solidification range,

David J. Browne; Denis OMahoney

2001-01-01

384

Forced Convection Film Boiling Heat Transfer Over a Vertical Cylinder  

Microsoft Academic Search

The knowledge of subcooled film boiling heat transfer is important as the basis of understanding the reflooding phenomenon during emergency cooling in a nuclear reactor under a loss-of-coolant accident. In this study, forced convection film boiling heat transfer from a vertical cylinder in Freon-113 flowing upward along the cylinder was measured for the flow velocities ranging from 0 to 1.3

Q. S. Liu; K. Fukuda; M. Shiotsu

2011-01-01

385

Simulating heat and mass transfer in regular distillation column packing  

Microsoft Academic Search

Plane-parallel packing of Mellapack 250X type (without perforations) is considered. Equation systems are given that describe\\u000a the motion and heat and mass transfer in a layer of liquid and vapor. Calculations have been performed on nonstationary heat\\u000a and mass transfer in cells of several types by the use of the STAR-CD software and the subroutines Star-Design and Pro-amm.\\u000a Graphs are

I. A. Arkharov; E. S. Navasardyan

2006-01-01

386

Surface heat transfer coefficients of pin-finned cylinders  

Microsoft Academic Search

An experimental investigation was conducted to measure heat-transfer coefficients for a 15.24-centimeter-diameter cylinder with pin fins on its surface. Pin diameters of 0.3175 and 0.6350 centimeter with staggered pin spacings of 3 and 4 pin diameters and pin lengths of 5, 7, and 9 pin diameters were tested. Flow was normal to the axis of the cylinder, and local heat-transfer

G. J. Vanfossen Jr.

1975-01-01

387

Heat transfer measurements from a smooth NACA 0012 airfoil  

NASA Astrophysics Data System (ADS)

Local convective heat transfer coefficients were measured from a smooth NACA 0012 airfoil having a chord length of 0.533 m. Flight data were taken for the smooth airfoil at Reynolds numbers based on chord in the range 1.24 to 2.50 million and at various angles of attack up to 4 deg. During these flight tests, the freestream velocity turbulence intensity was found to be very low. Wind tunnel data were acquired in the Reynolds number range 1.20 to 4.52 million and at angles of attack from -4 to +8 deg. The turbulence intensity in the IRT was 0.5-0.7 percent with the cloud-generating sprays off. A direct comparison between the results obtained in flight and in the IRT showed that the higher level of turbulence intensity in the IRT had little effect on the heat transfer for the lower Reynolds numbers but caused a moderate increase in heat transfer at the higher Reynolds numbers. Turning on the cloud-generating spray nozzle atomizing air in the IRT did not alter the heat transfer. The present data were compared with leading-edge cylinder and flat plate heat transfer correlations that are often used to estimate airfoil heat transfer in computer codes.

Poinsatte, Philip E.; van Fossen, G. J.; Newton, James E.; de Witt, Kenneth J.

1991-12-01

388

Flow and heat transfer with impinging jets and rough surfaces  

NASA Astrophysics Data System (ADS)

A series of studies were undertaken to investigate heat transfer from impinging jets and rough surfaces. In some of the studies, liquid crystals and naphthalene sublimation techniques were developed and used to determine the temperature distribution and the heat (mass) transfer coefficients, respectively. In the process of these investigations, a new data acquisition system, operated and controlled by computers, was developed, constructed, tested, and employed. A Laser-Doppler velocimeter was used to measure velocity and Reynold stresses in a two-dimensional wall jet. Single, multiple, and oblique jets, and the effects of entrainment and confinement on impingement heat transfer were studied. Investigations of three-dimensional heat (mass) transfer at the base of a cylinder protruding from a surface was carried out. Similar tests with an array of in-line and staggered cylinders were also conducted. The local heat transfer from a surface covered with two-dimensional periodic ribs was investigated. Distribution of the heat transfer coefficient on bottom and sidewall surfaces of a two dimensional cavity was experimentally determined.

Goldstein, R. J.; Jabbari, M. Y.

1987-07-01

389

Heat transfer from an array of heated cylindrical elements of an adiabatic channel wall  

NASA Astrophysics Data System (ADS)

This thesis describes an experimental study of the fluid dynamics and heat transfer characteristics of Laminar air flow across cylindrical elements mounted on one wall of a vertical adiabatic channel. Various combinations of approach velocity and channel widths were employed and the variations of the row by row heat transfer coefficients between elements of the array and the air stream were determined.

Piatt, James D., Jr.

1986-09-01

390

Heat transfer enhancement in latent heat thermal energy storage system by using the internally finned tube  

Microsoft Academic Search

The heat transfer enhancement in the latent heat thermal energy storage system by using an internally finned tube is presented in this paper. The phase change material fills the annular shell space around the tube, while the transfer fluid flows within the internally finned tube. The melting of the phase change material is described by a temperature transforming model coupled

Yuwen Zhang; A. Faghri

1996-01-01

391

Heat and momentum transfer for compact louvered fin-and-tube heat exchangers in wet conditions  

Microsoft Academic Search

The air side performances of two louvered fin surfaces under dehumidifying conditions were examined in this study. The test results indicated that the effect of fin pitch on the heat transfer performance is comparatively small, and the friction factors increase significantly with fin pitch for fully wet conditions. The effect of inlet relative humidity on the sensible heat transfer performance

Chi-Chuan Wang; Yur-Tsai Lin; Chi-Juan Lee

2000-01-01

392

Transfer heat in a resin sheath  

Microsoft Academic Search

As a material of construction for heat exchangers, fluoropolymers offer a combination of low cost and performance that is difficult for other materials to match. Durable, pliable, and less brittle than glass and graphite, fluoropolymers are generally specified over those materials in heat exchangers. Fluoropolymers have also displaced certain metals, depending on their susceptibility to corrosion from aggressive chemicals. Since

Wharry; S. R. Jr

1996-01-01

393

The Experimental Study on Heat Transfer Characteristics of The External Heat Exchanger  

NASA Astrophysics Data System (ADS)

Using the external heat exchanger in large-scale CFB boilers can control combustion and heat transfer separately, make the adjustments of bed temperature and steam temperature convenient. The state of gas-solid two phase flow in the external heat exchanger is bubbling fluidized bed, but differs from the regular one as there is a directional flow in it. Consequently, the temperature distribution changes along the flow direction. In order to study the heat transfer characteristics of the water cooled tubes in the bubbling fluidized bed and ensure the uniformity of heat transfer in the external heat exchanger, a physical model was set up according to the similarity principle and at the geometric ratio of 1?28 to an external heat exchanger of a 300MW CFB boiler. The model was connected with an electrically heated CFB test-bed which provides the circulating particles. The influencing factors and the distribution rule of the particles' heat transfer coefficient in the external heat exchanger were assessed by measuring the temperature changes of the water in the tubes and different parts of particles flow along the flow direction. At the end, an empirical correlation of particles' heat transfer coefficient in external heat exchanger was given by modifying the Veedendery empirical correlation.

Ji, X. Y.; Lu, X. F.; Yang, L.; Liu, H. Z.

394

Mass and Heat Transfer in Crushed Oil Shale.  

National Technical Information Service (NTIS)

Heat and mass transfer between gases and oil-shale particles are both important for all proposed retorting processes. Past studies of transfer in packed beds, which have disagreed substantially in their results, have nearly all been done with beds of regu...

J. F. Carley J. S. Straub L. L. Ott

1984-01-01

395

Computational radiative heat transfer in homogeneous and nonhomogeneous nonscattering media  

Microsoft Academic Search

A computational methodology was developed for calculating radiative heat transfer in gaseous nonhomogeneous nonscattering media with complex emission and absorption spectra. The technique can be used in both equilibrium and nonequilibrium situations. Test cases applied to an Aeroassisted Orbital Transfer Vehicle (AOTV) were investigated, and results are presented herein. Nonequilibrium compositions and temperatures were taken from NASA-Langley three-dimensional hypersonic flowfield

Perry Lee Fuehrer

1993-01-01

396

Transcillatory heat transfer in a liquid with gas bubbles  

NASA Astrophysics Data System (ADS)

The article describes the model of transcillatory heat transfer induced by gas bubbles buoyant in liquid. The temperature problem is reduced to the equivalent integral equation, and the velocity field in liquid phase is presented as structures of running and stationary waves. The relations for computing the coefficient of transcillatory transfer have been found.

Nigmatulin, R. I.; Filippov, A. I.; Khismatullin, A. S.

2012-12-01

397

Natural convection heat transfer analysis of ATR fuel elements  

Microsoft Academic Search

Natural convection air cooling of the Advanced Test Reactor (ATR) fuel assemblies is analyzed to determine the level of decay heat that can be removed without exceeding the melting temperature of the fuel. The study was conducted to assist in the level 2 PRA analysis of a hypothetical ATR water canal draining accident. The heat transfer process is characterized by

Langerman

1992-01-01

398

Conjugate heat transfer in enclosures with openings for ventilation  

Microsoft Academic Search

Conjugate heat transfer by natural convection and conduction in enclosures with openings has been studied by a numerical method. The enclosure contained a chimney consisting of a vertical solid wall, which was insulated on one side and a constant heat flux applied on the other. Vertical boundaries with openings were isothermal and horizontal boundaries adiabatic. These problems are encountered in

E. Bilgen; T. Yamane

2004-01-01

399

Heat Transfer Experiments on a Pulse Detonation Driven Combustor.  

National Technical Information Service (NTIS)

Heat transfer experiments were conducted using a heat exchanger behind a pulse detonation combustor and a Garrett automotive turbocharger at the Air Force Research Lab (AFRL). The equivalence ratio and purge fraction were held at 1.0 and 0.9, respectively...

N. C. Longo

2011-01-01

400

Heat transfer coefficients for leaves on orchard apple trees  

Microsoft Academic Search

The coefficient for heat transfer from apple tree leaves was measured from the energy balance of leaves which were prevented from transpiring by applying Vaseline (petroleum jelly). Vaseline had negligible effect on the absorption of short-wave radiation by the leaves. The Nusselt number (Nu) describing heat flux from a leaf in terms of its average temperature was related to Reynolds

M. R. Thorpe; D. R. Butler

1977-01-01

401

Thermal vacuum sensor with compensation of heat transfer  

Microsoft Academic Search

The results of investigation on thin-film vacuum sensor have been presented. The sensor was composed of a heating resistor and a thermopile, which were made by thin-film technology on a glass foil substrate. To improve the sensitivity of the sensor and extend its measurement range, a special design was chosen, which enabled us to reduce the heat transfer by radiation

T. M. Berlicki

2001-01-01

402

Students' Misconceptions about Heat Transfer Mechanisms and Elementary Kinetic Theory  

ERIC Educational Resources Information Center

|Heat and thermodynamics is a conceptually rich area of undergraduate physics. In the Indian context in particular there has been little work done in this area from the point of view of misconceptions. This prompted us to undertake a study in this area. We present a study of students' misconceptions about heat transfer mechanisms, i.e. conduction,

Pathare, S. R.; Pradhan, H. C.

2010-01-01

403

Analytical solution for unsteady heat transfer in a pipe  

Microsoft Academic Search

Under consideration is transient, convective heat transfer to a fluid flow within a pipe due to a sudden change in the temperature of the ambient medium outside the pipe. A solution is developed by the Laplace transformation, for the fastest portion of the transient, which gives the pipe wall temperature, surface heat flux, and fluid bulk mean temperature. These analytical

J. Sucec

1988-01-01

404

Heat-transfer measurements of the 1983 Kilauea lava flow  

SciTech Connect

Convective heat flow measurements of a basaltic lava flow were made during the 1983 eruption of Kilauea volcano in Hawaii. Eight field measurements of induced natural convection were made, giving heat flux values that ranged from 1.78 to 8.09 kilowatts per square meter at lava temperatures of 1088 and 1128 degrees Celsius, respectively. These field measurements of convective heat flux at subliquidus temperatures agree with previous laboratory measurements in furnace-melted samples of molten lava, and are useful for predicting heat transfer in magma bodies and for estimating heat extraction rates for magma energy.

Hardee, H.C.

1983-10-07

405

Pin-fin heat transfer - Contribution of the wall and the pin to the overall heat transfer  

Microsoft Academic Search

The differences in the heat transfer coefficient between the pin and the wall in pin-fin heat transfer was determined for three pin length to diameter ratios. A staggered pin-fin array was used with a 50 percent duct flow blockage by the pins. The axial pitch-to-pin diameter ratio, X\\/D, was 1.5 and the transverse pitch-to-diameter ratio, S\\/D, was 2.0. Three pin

A. M. Al Dabagh; G. E. Andrews

1992-01-01

406

The heat transfer phenomenon across mold flux to copper mold in continuous casting  

NASA Astrophysics Data System (ADS)

In the development of steel technology, continuous casting has become the main process route for mass production of steel today. 1100 million tons of steel was casted annually corresponding to more than 90% of the total steel production in the world. Like any other new process, continuous casting is efficient. However, it also introduces new types of defects, like oscillation marks, corner cracks, facial cracks, macro inclusions, etc. Currently, a wealth of experience in industry has been developed to improve slab surface qualities. Most of the research has indicated that the final cast slab surface is strongly dependent upon the heat release rate from the steel strand, i.e., heat transfer rate from the partially solidified strand to caster mold. Mold fluxes have been widely used to infiltrate in between the caster mold and strand to moderate the heat transfer rate. The main goal of this study is to explore the effects of mold flux composition and solidification on heat transfer rates, especially on radiative heat transfer rates. It has been shown in the work that both solid crystalline and glassy phase films have different thermal resistance and affect the radiative heat transfer rate, and the crystallization behavior of the mold flux is the primary factor affecting the overall heat transfer rate in continuous casting. By using an infrared radiation emitter, which was developed at Carnegie Mellon University, a radiative heat flux was applied to a copper mold covered with solid mold flux disk to simulate the radiative heat transfer phenomena in continuous casting. The solid slag disk could either be glass or a mixture of glass and precipitated crystals. The kinetics of mold slag crystallization was studied by the recently developed double hot thermocouple techniques (DHTT) as well. It has been investigated that the effect of full crystallization of a slag disk is able to reduce the heat transfer rate by 20% in the meniscus area in this work. By studying the heat transfer mechanism proposed here, the hypothesis could be used in real casting industry to help moderating heat transfer rates to eliminate or minimize oscillation marks, to achieve a defects free final slab.

Wang, Wanlin

407

The influence of oil on nucleate pool boiling heat transfer  

NASA Astrophysics Data System (ADS)

The influence of various oil contents in R134a is investigated for nucleate pool boiling on copper tubes either sandblasted or with enhanced heating surfaces (GEWA-B tube). Polyolester oils (POE) (Reniso Triton) with medium viscosity 55 cSt (SE55) and high viscosity 170 cSt (SE170) were used. Heat transfer coefficients were obtained for boiling temperatures between -28.6 and +20.1C. The oil content varied from 0 to 5% mass fraction. For the sandblasted tube and the SE55 oil the heat transfer coefficients for the refrigerant/oil-mixture can be higher or lower than those for the pure refrigerant, depending on oil mass fraction, boiling temperature and heat flux. In some cases the highest heat transfer coefficients were obtained at a mass fraction of 3%. For the 170 cSt oil there is a clear decrease in heat transfer for all variations except for a heat flux 4,000 W/m2 and -10.1C at 0.5% oil content. The heat transfer coefficients are compared to those in the literature for a smooth stainless steel tube and a platinum wire. For the enhanced tube and 55 cSt oil the heat transfer coefficients are clearly below those for pure refrigerant in all cases. The experimental results for the sandblasted tube are compared with the correlation by Jensen and Jackman. The calculated values are within +20 and -40% for the medium viscosity oil and between +50% and -40% for the high viscosity oil. A correlation for predicting oil-degradation effects on enhanced surfaces does not exist.

Spindler, Klaus; Hahne, Erich

2009-05-01

408

Heat Transfer in Severe Accident Simulations.  

National Technical Information Service (NTIS)

For cask designers to improve analytical thermal modeling capabilities, it is important to define the ''thermal insult'' a fire test provides to a package. In order to define the thermal environment, temperature and heat flux measurements must be obtained...

N. R. Keltner K. B. Sobolik J. L. Moya

1989-01-01

409

Heat transfer coefficients beneath inclined turbulent impinging jets  

NASA Astrophysics Data System (ADS)

An experimental study of the local heat and mass transfer coefficients associated with the impingement of inclined turbulent circular jets onto flat plates is presented. A single free jet exiting into initially stagnant surroundings was considered, and the nozzle inclination, alpha, was varied from 30 to 90 deg to the impingement surface. The heat transfer rate is virtually insensitive to nozzle inclination if the distance along the axis of the jet is used. The 'thin-film' naphthalene sublimation technique was employed for the mass transfer measurements.

Oladiran, M. T.

410

Effects of simultaneous transfer of heat and tritium through LiPb or Flibe blanket  

Microsoft Academic Search

Transport of tritium (T) and heat is calculated to estimate the performance of liquid Li17Pb83 (LiPb) or Li2BeF4 (Flibe) as a T-breeder in a fusion reactor blanket. T is bred in such a way of low leak to facilities outside and continuous recovery by a removal system, and heat is transferred through structural walls to He coolant efficiently. In this

S. Fukada; Y. Edao; A. Sagara

2010-01-01

411

Heat transfer characteristics of a solar air heater used for drying purposes  

Microsoft Academic Search

A temperature rise of only 3 to 6°C above ambient has been recommended for drying cereal grains. Such temperatures can be attained in a simple unglazed solar air heater. However, the plate efficiency factor is low. The present work involves the provision of protruding wires on the underside of the absorber plate to improve the heat transfer characteristics and hence

K. Prasad; S. C. Mullick

1983-01-01

412

Numerical Simulation of Flow and Heat Transfer around Complex Configurations by a Chimera RANS Method  

Microsoft Academic Search

A local-analytic-based numerical method has been used in conjunction with advanced turbulence models for simulation of flow and heat transfer around complex configurations encountered in mechanical, civil, ocean, coastal, offshore, and hydraulic engineering applications. The method solves unsteady Navier- Stokes equations in stationary and moving curvilinear coordinates. A chimera domain decomposition approach is implemented to facilitate efficient simulation of laminar

Hamn-Ching Chen

2005-01-01

413

Rod Bundle Heat Transfer: Steady-State Steam Cooling Experiments  

SciTech Connect

Through the joint efforts of the Pennsylvania State University and the United States Nuclear Regulatory Commission, an experimental rod bundle heat transfer (RBHT) facility was designed and built. The rod bundle consists of a 7 x 7 square pitch array with spacer grids and geometry similar to that found in a modern pressurized water reactor. From this facility, a series of steady-state steam cooling experiments were performed. The bundle inlet Reynolds number was varied from 1 400 to 30 000 over a pressure range from 1.36 to 4 bars (20 to 60 psia). The bundle inlet steam temperature was controlled to be at saturation for the specified pressure and the fluid exit temperature exceeded 550 deg. C in the highest power tests. One important quantity of interest is the local convective heat transfer coefficient defined in terms of the local bulk mean temperature of the flow, local wall temperature, and heat flux. Steam temperatures were measured at the center of selected subchannels along the length of the bundle by traversing miniaturized thermocouples. Using an analogy between momentum and energy transport, a method was developed for relating the local subchannel centerline temperature measurement to the local bulk mean temperature. Wall temperatures were measured using internal thermocouples strategically placed along the length of each rod and the local wall heat flux was obtained from an inverse conduction program. The local heat transfer coefficient was calculated from the data at each rod thermocouple location. The local heat transfer coefficients calculated for locations where the flow was fully developed were compared against several published correlations. The Weisman and El-Genk correlations were found to agree best with the RBHT steam cooling data, especially over the range of turbulent Reynolds numbers. The effect of spacer grids on the heat transfer enhancement was also determined from instrumentation placed downstream of the spacer grid locations. The local heat transfer was found to be greatest at locations immediately downstream of the grid, and as the flow moved further downstream from the grid it became more developed, thus causing the heat transfer to diminish. The amount of heat transfer enhancement was found to depend not only on the spacer grid design, but also on the local Reynolds number. It was seen that decreasing Reynolds number leads to greater heat transfer enhancement. (authors)

Spring, J.P.; McLaughlin, D.M. [The Pennsylvania State University, 201 Shields Building University Park, PA 16802 (United States)

2006-07-01

414

Experimental investigation of transient boiling heat transfer in microchannels  

Microsoft Academic Search

This paper presents an experimental investigation of flow boiling heat transfer in a single 0.312.7mm2 rectangular microchannel. Water and ethanol are employed as test fluids. The test section, which is made of the nickel alloy Inconel 600, is electrically heated. The examined parameter ranges are: mass fluxes between 50 and 500kg\\/m2s and heat fluxes up to 400kW\\/m2 at an outlet

M. Cortina Daz; J. Schmidt

2007-01-01

415

Experimental study on liquid flow and heat transfer in micro square pin fin heat sink  

Microsoft Academic Search

The heat sinks, with the total heat transfer area of 2020mm2 and an array of 625 staggered micro square pin fins of 559559?m2 or 445445?m2 cross section by 3mm height were fabricated on a copper test section. Using deionized water as coolant liquid, the flow and heat transfer performance of the high pin fins were studied with the Reynolds number

Minghou Liu; Dong Liu; Sheng Xu; Yiliang Chen

2011-01-01

416

Use of heat flux sensors for studying local heat transfer in pipes  

Microsoft Academic Search

Local heat transfer in the flow of air in a circular pipe 36 mm in diameter and 2000 mm in length was measured with single heat flux sensors and with a battery of such sensors. Data reveal an intensity of local heat transfer in the region of developed flow at Reynolds numbers in the range 10,000-120,000, length-to-diameter ratios above 50,

V. M. Legkii; O. A. Gerashchenko; V. D. Burlei

1978-01-01

417

Subchannel based radiation heat transfer model in COBRA-TF  

SciTech Connect

COBRA-TF is a two-fluid, three-dimensional, thermal-hydraulic computer code designed to model the hot channel of a light-water reactor during the reflood phase of a loss-of-coolant accident. The reflood phase is characterized by a superheated vapor coolant containing dispersed liquid droplets. Heat transfer to the vapor and droplets is poor, resulting in high temperatures at the surface of the fuel rods. Because of the high temperatures, heat transfer by radiation may account for a large portion of the heat removed from the fuel rods.

Kohrt, R.J.; McCann, R.A.; Kelly, J.M.

1984-06-01

418

Design and operation of solar thermal heat transfer systems  

SciTech Connect

The importance of heat transfer systems in the collection and use of solar energy is discussed. The success or failure of many solar energy systems has been determined by the design of the heat transfer system. This report includes a short summary of some of the DOE sponsored solar industrial process heat sites. From the design, construction, and operation of these systems many lessons were learned which will be important to designers and potential users of solar thermal systems. Also included is a discussion of solar collector foundation over-design that has increased the collector system costs.

Rush, E.E.

1985-01-01

419

Heat transfer from a turbulent, swirling, impinging jet  

NASA Astrophysics Data System (ADS)

This paper presents mass and heat transfer rates associated with orthogonal impingement of single, swirling, air jets onto flat plates. Mass transfer data were determined using a thin-film naphthalene sublimation technique and the Chilton-Colburn analogy was employed to infer the corresponding heat transfer coefficients. The swirl number was varied from 0 to 0.48 and the nozzle-to-plate separations ranged from 2 to 12 jet diameters. Jet Reynolds numbers of 32,000 and 60,000 (based on the mean nozzle exit velocity in the non-swirling case) were also studied. The application of swirl was found to significantly reduce the heat transfer rates. The average Nusselt numbers, for particular impingement areas, were correlated by means of a simple power-law dependence on the swirl and Reynolds numbers and also on the nozzle-to-plate separation.

Ward, J.; Mahmood, M.

420

Boiling heat transfer in a small horizontal rectangular channel  

SciTech Connect

Compact heat exchangers have traditionally found wide application in the transportation industry, where they are used as evaporators and condensers in vapor compression cycles for air conditioning and refrigeration. Such heat exchangers possess numerous attractive features including high thermal effectiveness, small size, low weight, design flexibility, and pure counterflow, and they can accommodate multiple streams. Today, there is a widespread interest in expanding the range of application of compact heat exchangers to include phase-change heat transfer in the process industries, among others. An overall objective of this effort is to provide the basis for establishing design technology in this area. In the present study, small channel flow boiling heat transfer was extended to a rectangular channel (4.06 {times} 1.70 mm) using refrigerant 12 (R-12). As with the circular tube studies, the flow channel wall was electrically heated providing a constant heat flux. Tests were performed over a quality range of 0.15 to 0.80, and large ranges of mass fluxes (50 to 400 kg/m{sup 2}s) and heat flux (4 to 34 kW/m{sup 2}). Heat transfer was measured and results are compared with correlation predictions.

Tran, T.N.; Wambsganss, M.W.; Jendrzejczyk, J.A. [Argonne National Lab., IL (United States); France, D.M. [Illinois Univ., Chicago, IL (United States). Dept. of Mechanical Engineering

1993-08-01

421

Radiative heat transfer in turbulent MHD channel flow  

SciTech Connect

Radiative heat transfer in a MHD channel has been studied for fully developed turbulent flow of an electrically conducting fluid. A uniform magnetic field is imposed transverse to the flow direction between the electrically insulated parallel plates. Thermal entry region is analyzed for constant wall temperature including viscous dissipation and Joulean heating. A van Dreist mixing length model with Mei and Squire correction factor is used for eddy diffusivity of momentum and a modified Cebeci model is used for eddy conductivity. Both gray and real (non-gray) gas models of radiation are examined. An exponential wide band model is employed in evaluation of radiative heat flux for a real gas. Also, the contribution of a seed material to the radiative transfer is considered. The integro-differential equation for thermal energy transport is solved by a finite difference iterative method. Effects of control parameters such as Reynolds and Hartmann numbers, wall temperature, channel height, and partial pressures of participating gases on temperature profiles and heat transfer are studied. Results for Nusselt number, bulk temperature, and temperature profiles are reported for fully developed and developing thermal profiles. Furthermore, results are presented along the channel for these quantities for various parameters. Effect of variation of electrical conductivity with temperature is considered. For practical values of parameters as found in proposed MHD generators it is shown that radiative heat transfer is a major mechanism of heat transfer in the channel and accelerates the thermal development and results in reduced gas temperature profiles.

Alipour-Haghighi, F.

1981-01-01

422

Heat Transfer Enhancement in Separated and Vortex Flows  

SciTech Connect

This document summarizes the research performance done at the Heat Transfer Laboratory of the University of Minnesota on heat transfer and energy separation in separated and vortex flow supported by DOE in the period September 1, 1998--August 31, 2003. Unsteady and complicated flow structures in separated or vortex flows are the main reason for a poor understanding of heat transfer under such conditions. The research from the University of Minnesota focused on the following important aspects of understanding such flows: (1) Heat/mass transfer from a circular cylinder; (2) study of energy separation and heat transfer in free jet flows and shear layers; and (3) study of energy separation on the surface and in the wake of a cylinder in crossflow. The current study used three different experimental setups to accomplish these goals. A wind tunnel and a liquid tunnel using water and mixtures of ethylene glycol and water, is used for the study of prandtl number effect with uniform heat flux from the circular cylinder. A high velocity air jet is used to study energy separation in free jets. A high speed wind tunnel, same as used for the first part, is utilized for energy separation effects on the surface and in the wake of the circular cylinder. The final outcome of this study is a substantial advancement in this research area.

Richard J. Goldstein

2004-05-27

423

Heat Transfer Characteristics of Slush Nitrogen in Turbulent Pipe Flows  

NASA Astrophysics Data System (ADS)

Slush fluids, such as slush hydrogen and slush nitrogen, are two-phase (solid-liquid) single-component cryogenic fluids containing solid particles in a liquid, and consequently their density and refrigerant capacity are greater than for liquid state fluid alone. This paper reports on the experimental results of the forced convection heat transfer characteristics of slush nitrogen flowing in a pipe. Heat was supplied to slush nitrogen by a heater wound around the copper pipe wall. The local heat transfer coefficient was measured in conjunction with changes in the velocity and the solid fraction. The differences in heat transfer characteristics between two-phase slush and single phase liquid nitrogen were obtained, and the decrease in heat transfer to slush nitrogen caused by the previously observed pressure drop reduction was confirmed by this study. Furthermore, for the purpose of establishing the thermal design criteria for slush nitrogen in the case of pressure drop reduction, the heat transfer correlation between the experimental results and the Sieder-Tate Equation was obtained.

Ohira, K.; Ishimoto, J.; Nozawa, M.; Kura, T.; Takahashi, N.

2008-03-01

424

Numerical simulation of contact heat transfer between particles by TDEM  

NASA Astrophysics Data System (ADS)

Heat transfer in particulate systems plays an important role in a range of industrial processes, such as drying, heating, cooling, and so on. However, the inter-particle heat transfer mechanism is comparatively less understood. Due to the multi-scale complexity of the system and the limitations of measurement techniques, the details of the processes are difficult to investigate experimentally. DEM is a powerful tool for us to obtain insight into the dynamics of particulate system. To extend the classical DEM to the Thermal Discrete Element Method (TDEM) for particulate system with heat transfer, the effect of softening treatment for TDEM was analyzed, which results in the change of some important micro-behaviors of inter-particle, such as impact time and contact area etc, and the unrealistic heat transfer between particles. Two coefficients, time restoration coefficient Crt and area restoration coefficient Cra, were derived to simulate the contact heat transfer between particles more realistically even if particle stiffness is artificially adjusted by several orders while a large time step is taken to save computational cost.

Lu, L. Y.; Gu, Z. L.; Lei, K. B.; Kase, Kiwamu

2010-03-01

425

Heat transfer during the boiling of acetone and ethyl alcohol in a thermosiphon with porous capillary structures on the heat-transfer face  

NASA Astrophysics Data System (ADS)

It is shown experimentally that heat transfer during boiling on a 0.004-m-diameter heat-transfer surface of a thermosiphon conforms to the rules established for the case of boiling in a large volume. The heat transfer is shown to become unstable in the presence of brass screens on the heat-transfer surface. Considerable intensification and stabilization of the boiling process are achieved by using a perforated Teflon plate with a free section ratio of 0.44 as a porous capillary structure on the heat-transfer surface. For this case, heat transfer equations valid for the temperature head range 3-30 K are obtained.

Kashirskii, V. G.; Pechenegov, Iu. Ia.; Serov, Iu. I.

1983-04-01

426

Experimental investigation of heat transfer and burnout in condition of nonuniform megawatt heat fluxes  

SciTech Connect

In this paper burnout is investigated in tubes under nonuniform heating on the perimeter. Data on heat transfer and critical heat flux (q{sub chf}) in the case of water were obtained for ranges of mass velocity {rho}w = 200--3000 kg/m{sup 2} s, pressure p = 1--1 MPa, and inlet water temperature T = 25--98{degrees}C. The test section was a horizontal copper tube of 21 mm outer diameter, 8 mm inner diameter with a technically smooth surface and heat transfer-intensifying twisted tape and porous sintered coating. The test section was heated by bombardment with electrons. It is established that a redistribution of heat fluxes and an increase of wall temperature fluctuations occur at burnout. The range of regime parameters to prevent burnout of a heat transfer surface is determined.

Komendantov, A.S.; Kuzma-Kichta, Y.A.; Vasil'eva, L.T.; Ovodkov, A.A. (Moscow Power Engineering Inst., Moscow (SU))

1991-01-01

427

Analysis of convective instability and heat transfer characteristics of nanofluids  

NASA Astrophysics Data System (ADS)

The convective instability driven by buoyancy and heat transfer characteristics of nanofluids are investigated analytically. This paper proposes a factor which describes the effect of nanoparticle addition on the convective instability and heat transfer characteristics of a base fluid. The Bruggeman model based on the mean field approach for expressing the thermal conductivity enhancement is chosen as a lower bound of the thermal conductivity relationship. The results show that as the density and heat capacity of nanoparticles increase and the thermal conductivity and the shape factor of nanoparticles decrease, the convective motion in a nanofluid sets in easily. The heat transfer coefficient of a nanofluid is enhanced by all parameters with respect to the volume fraction of nanoparticles.

Kim, Jake; Kang, Yong Tae; Choi, Chang Kyun

2004-07-01

428

Heat and mass transfer in water-laden sandstone: microwave heating  

Microsoft Academic Search

Our previous theoretical model was extended to predict the heat and mass transfer phenomena in microwave-heated porous materials. A water-filled sandstone was heated in microwaves and its drying rates and temperature profiles were measured. Predictions agree well with observations. Besides moisture loss rates and temperature profiles, the model also predicts local moisture content, gas densities, and pressure. These latter quantities

Chen Kou Wei; H. T. Davis; E. A. Davis; Joan Gordon

1985-01-01

429

Heat transfer in the inverted meniscus type evaporator at high heat fluxes  

Microsoft Academic Search

A one-dimensional mathematical model of the heat transfer during evaporation of the liquid from the liquid-vapor interface located in a porous structure into the dry region between the interface and the solid heated surface is developed for the case when the vapor flows through the narrow dry porous zone along the heated surface towards the vapor channel. The model predicts

D. Khrustalev; A. Faghri

1995-01-01

430

Optimum Allocation Of Heat Transfer Surface In An Absorption Heat Pump  

Microsoft Academic Search

A simplified model of an absorption heat pump is used to enable a compact formulation of the problem of the optimum allocation of heat transfer surface. This optimization problem is similar to the power cycle optimizations that have appeared frequently in recent literature. The task is to maximize the cycle output by varying the heat exchanger sizes with the constraint

Keith E. Herold; Reinhard Radermacher

1990-01-01

431

Natural convection heat transfer from a thermal heat source located in a vertical plate fin  

Microsoft Academic Search

A steady state conjugate conductionconvection investigation is performed on vertical plate fin in which a small heat source is located. Heat from the fin surface is transferred to the surroundings by laminar natural convection. The governing equations for the problem are the heat conduction equation for the fin and the boundary layer equations, which are continuity, momentum and energy equations,

Moghtada Mobedi; Bengt Sunden

2006-01-01

432

Heat Transfer Analysis of a Packed Bed-PCM Capsules Latent Heat Thermal Energy Storage System  

Microsoft Academic Search

Heat transfer analysis of a packed bed-PCM latent heat thermal energy storage system is presented in this study. The packed bed cylindrical column is filled with spherical capsules of PCM (paraffin wax) that is used for a solar water heating application. In this study, the physical model is developed to use for analyzing the thermal performance of packed bed-PCM latent

Z. S. Abdel-Rehim

2011-01-01

433

A generalized approach to heat transfer in pipe flow with internal heat generation  

Microsoft Academic Search

In the last few years, there has been a renewed interest in the molten salt reactor (MSR), one of the Generation IV International Forum concepts, which adopts a circulating molten salt mixture as both heat generator (fuel) and coolant. The heat transfer of a fluid with internal heat generation depends on the strength of the source whose influence on the

Valentino Di Marcello; Antonio Cammi; Lelio Luzzi

2010-01-01

434

Numerical technique for modeling conjugate heat transfer in an electronic device heat sink  

Microsoft Academic Search

A fast running computational algorithm based on the volume averaging technique (VAT) is developed to simulate conjugate heat transfer process in an electronic device heat sink. The goal is to improve computational capability in the area of heat exchangers and to help eliminate some of empiricism that leads to overly constrained designs with resulting economic penalties.VAT is tested and applied

Andrej Horvat; Ivan Catton

2003-01-01

435

Cross-flow heat transfer in fixed bed  

NASA Astrophysics Data System (ADS)

Radial flow reactor operated at cross-flow heat transfer is focused for large scale methanol synthesis. The effects of operating conditions including the reactor inlet air temperature, the heating pipe temperature and the air flow rate on the cross-flow heat transfer were investigated and results show that the temperature profile of the area in front of the heating pipe is slightly affected by all the operating conditions. The main area whose temperature profile is influenced is located behind the heating pipe. The heat transfer direction is related to the direction of the flow. In order to obtain the basic parameters for radial flow reactor designing calculation, the dimensionless number group method was used for data fitting of the bed effective thermal conductivity and the wall heat transfer coefficient which were calculated by the mathematical model with the product of Reynolds number and Prandtl number. The comparison of experimental data and calculated values shows that the calculated values fit the experimental data satisfactorily and the formulas can be used for reactor designing calculation.

Ma, Hongfang; Zhang, Haitao; Ying, Weiyong; Fang, Dingye

2013-06-01

436

Universality of energy conversion efficiency for optimal tight-coupling heat engines and refrigerators  

NASA Astrophysics Data System (ADS)

A unified ?-criterion for heat devices (including heat engines and refrigerators), which is defined as the product of the energy conversion efficiency and the heat absorbed per unit time by the working substance (de Toms et al 2012 Phys. Rev. E 85 010104), is optimized for tight-coupling heat engines and refrigerators operating between two heat baths at temperatures Tc and Th( > Tc). By taking a new convention on the thermodynamic flux related to the heat transfer between two baths, we find that for a refrigerator tightly and symmetrically coupled with two heat baths, the coefficient of performance (i.e., the energy conversion efficiency of refrigerators) at maximum ? asymptotically approaches \\sqrt{\\varepsilon _C} when the relative temperature difference between two heat baths \\varepsilon _C^{-1}\\equiv (T_h-T_c)/T_c is sufficiently small. Correspondingly, the efficiency at maximum ? (equivalent to maximum power) for a heat engine tightly and symmetrically coupled with two heat baths is proved to be \\eta _C/2+\\eta _C^2/8 up to the second order term of ?C ? (Th - Tc)/Th, which reverts to the universal efficiency at maximum power for tight-coupling heat engines operating between two heat baths at small temperature difference in the presence of left-right symmetry (Esposito et al 2009 Phys. Rev. Lett. 102 130602).

Sheng, Shiqi; Tu, Z. C.

2013-10-01

437

Field Measurements of Heating System Efficiency in Nine Electrically-Heated Manufactured Homes.  

SciTech Connect

This report presents the results of field measurements of heating efficiency performed on nine manufactured homes sited in the Pacific Northwest. The testing procedure collects real-time data on heating system energy use and heating zone temperatures, allowing direct calculation of heating system efficiency.

Davis, Bob; Siegel, J.; Palmiter, L.; Baylon, D.

1996-07-01

438

Effect of Cu-water nanofluid on the heat transfer by rotating heat pipe  

NASA Astrophysics Data System (ADS)

This paper presents a study on the effect of using Cu-water nanofluid on the heat transfer by rotating heat pipe (RHP). A mathematical model is presented of the RHP including, vapor velocity, gravity effect and taper angle. The study is carried out at different rotation speeds, RHP temperatures differences (?T) and masses of working fluid of the RHP. Using of Cu-water nanofluid with RHP decreases the liquid film thickness adjacent to its walls and increases the heat transfer by RHP compared with ordinary fluid. The heat transfer by RHP increases with increasing ?T and volume fraction and radius of solid nanoparticles. The maximum heat transfer by RHP at ?T=20 oC and ?=3000rpm increases by about 56% due to using Cu-water nanofluid with volume fraction 0.04 and nanoparticles radius 5nm.

Hassan, Hamdy; Harmand, Souad

2013-10-01

439

Heat transfer and flow characteristics around a finned-tube bank heat exchanger in fluidized bed  

NASA Astrophysics Data System (ADS)

Principal heat transfer mechanisms in a fluidized bed have been classified into three categories, i.e. solid convection, gas convection and radiation. Among these mechanisms, the solid convection is a dominant mechanism in the bubbling fluidized bed. This solid convection is substantially caused by the bubble movement, thus the visualization of the void fraction distribution becomes a very useful method to understand the characteristics of the fluidized-bed heat exchanger. In this study, the heat transfer coefficient and the void fraction around the heat transfer tube with annuler fin were measured. For the quantitative measurement of the void fraction, neutron radiography and image processing technique were employed. Owing to the existence of the annuler fin, the restriction of the particle movements was put. This restriction suppressed the disturbance caused by tubes, and the influence of the tube arrangement on the flow and heat transfer characteristics could be clearly expressed.

Honda, Ryosuke; Umekawa, Hisashi; Ozawa, Mamoru

2009-06-01

440

Particle shape effect on heat transfer performance in an oscillating heat pipe.  

PubMed

The effect of alumina nanoparticles on the heat transfer performance of an oscillating heat pipe (OHP) was investigated experimentally. A binary mixture of ethylene glycol (EG) and deionized water (50/50 by volume) was used as the base fluid for the OHP. Four types of nanoparticles with shapes of platelet, blade, cylinder, and brick were studied, respectively. Experimental results show that the alumina nanoparticles added in the OHP significantly affect the heat transfer performance and it depends on the particle shape and volume fraction. When the OHP was charged with EG and cylinder-like alumina nanoparticles, the OHP can achieve the best heat transfer performance among four types of particles investigated herein. In addition, even though previous research found that these alumina nanofluids were not beneficial in laminar or turbulent flow mode, they can enhance the heat transfer performance of an OHP. PMID:21711830

Ji, Yulong; Wilson, Corey; Chen, Hsiu-Hung; Ma, Hongbin

2011-04-05

441

Radiative heat transfer in turbulent MHD channel flow  

NASA Astrophysics Data System (ADS)

Radiative heat transfer in a MHD channel has been studied for fully developed turbulent flow of an electrically conducting fluid. A uniform magnetic field is imposed transverse to the flow direction between the electrically insulated parallel plates. Thermal entry region is analyzed for constant wall temperature including viscous dissipation and Joulean heating. A van Dreist mixing length model with Mei and Squire correction factor is used for eddy diffusivity of momentum and a modified Cebeci model is used for eddy conductivity. An exponential wide band model is employed in evaluation of radiative heat flux for a real gas. The tegro-differential equation for thermal energy transport is solved by a finite difference iterative method. It is shown that radiative heat transer is a major mechanism of heat transfer in the channel and accelerates the thermal development and results in reduced gas temperature profiles.

Alipour-Haghighi, F.

442

Unsteady Heat Transfer in Erosivity Experiments.  

National Technical Information Service (NTIS)

Although TiO2/wax liners are used in U. S. large caliber guns to reduce erosion, the erosion-reducing mechanisms of these liners is still under investigation. Two sets of investigators found a correlation between specific heat of the metal oxide and its a...

C. W. Nelson J. R. Ward

1972-01-01

443

Simulation of a High Efficiency Multi-bed Adsorption Heat Pump  

SciTech Connect

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 effectively transfers heat from beds being cooled to beds being heated, which enables high efficiency in thermally driven heat pumps. A simplified lumped-parameter model and detailed finite element analysis are used to simulate the performance of an ammonia-carbon sorption compressor, which is used to project the overall heat pump coefficient of performance. 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.

TeGrotenhuis, Ward E.; Humble, Paul H.; Sweeney, J. B.

2012-05-01

444

Heat transfer augmentation in the flueway of a water heater  

SciTech Connect

The effects of a twisted baffle tape on the heat transfer in the center flue tube of a gas-fired water heater are investigated both theoretically and experimentally. The combustion products enter the flue tube at a temperature of about 2300 F (1260/sup 0/C) and transfer heat by the combined modes of radiation and convection to the cross tape and the water-backed tube wall. The twisted tape causes an augmentation of the convective heat transfer from the flue gases to the wall surfaces. In addition, radiative heat transfer from the relatively hot cross tape plays an important role in the heat transfer to the tube wall, which has usually been neglected in the past. A theoretical study is performed under conditions of radiating gas flow and varying temperatures of the tube wall and cross tape along the flow direction. The results are compared to experimental measurements taken on one particular flue tube of a gas-fired water heater and are found to be in good agreement.

Beckermann, C.; Goldschmidt, V.W.

1986-01-01

445

Boiling heat transfer characteristics of nanofluids in a flat heat pipe evaporator with micro-grooved heating surface  

Microsoft Academic Search

An experimental study was performed to understand the nucleate boiling heat transfer of waterCuO nanoparticles suspension (nanofluids) at different operating pressures and different nanoparticle mass concentrations. The experimental apparatus is a miniature flat heat pipe (MFHP) with micro-grooved heat transfer surface of its evaporator. The experimental results indicate that the operating pressure has great influence on the nucleate boiling characteristics

Zhen-hua Liu; Jian-guo Xiong; Ran Bao

2007-01-01

446

Electrohydrodynamic convective heat transfer in a square duct.  

PubMed

Laminar to weakly turbulent forced convection in a square duct heated from the bottom is strengthened by ion injection from an array of high-voltage points opposite the heated strip. Both positive and negative ion injection are activated within the working liquid HFE-7100 (C(4)F(9)OCH(3)), with transiting electrical currents on the order of 0.1 mA. Local temperatures on the heated wall are measured by liquid crystal thermography. The tests are conducted in a Reynolds number range from 510 to 12,100. In any case, heat transfer is dramatically augmented, almost independently from the flow rate. The pressure drop increase caused by the electrohydrodynamically induced flow is also measured. A profitable implementation of the technique in the design of heat sinks and heat exchangers is foreseen; possible benefits are pumping power reduction, size reduction, and heat exchange capability augmentation. PMID:19426338

Grassi, Walter; Testi, Daniele

2009-04-01

447

Endwall heat transfer and pressure drop in scale-roughened pin-fin channels  

Microsoft Academic Search

There is a growing requirement for improved heat transfer performance for a number of electronic devices and this dictates a need to further elevate the endwall heat transfer performances for pin-fin channels. Driven by this need, a novel compound heat transfer enhancement (HTE) measure that combines deepened scales and pin-fin array is devised. Characteristics of heat transfer and pressure drop

Shyy Woei Chang; Arthur William Lees

2010-01-01

448

An Experimental Study on Heat Transfer Coefficients of a CO2Filled Thermosyphon  

Microsoft Academic Search

Because carbon dioxide is ozone friendly and has negligible global warming potential, it has received renewed interest in recent years as an important alternative refrigerant. In this article, the heat transfer characteristics of a carbon dioxide-filled two-phase closed thermosyphon were investigated experimentally, and the empirical heat transfer correlations are reported. The heat transfer data were analyzed, and heat transfer coefficients

S. J. Jeong

2011-01-01

449

Spray cooling heat-transfer with subcooled trichlorotrifluoroethane (Freon-113) for vertical constant heat flux surfaces  

SciTech Connect

Experiments were done using subcooled Freon-113 sprayed vertically downward. Local and average heat transfers were investigated fro Freon-113 sprays with 40 C subcooling, droplet sizes 200-1250{mu}m, and droplet breakup velocities 5-29 m/s. Full-cone type nozzles were used to generate the spray. Test assemblies consisted of 1 to 6 7.62 cm vertical constant heat flux surfaces parallel with each other and aligned horizontally. Distance between heated surfaces was varied from 6.35 to 76.2 mm. Steady state heat fluxes as high as 13 W/cm{sup 2} were achieved. Dependence on the surface distance from axial centerline of the spray was found. For surfaces sufficiently removed from centerline, local and average heat transfers were identical and correlated by a power relation of the form seen for normal-impact sprays which involves the Weber number, a nondimensionalized temperature difference, and a mass flux parameter. For surfaces closer to centerline, the local heat transfer depended on vertical location on the surface while the average heat transfer was described by a semi-log correlation involving the same parameters. The heat transfer was independent of the distance (gap) between the heated surfaces for the gaps investigated.

Kendall, C.M. [Lawrence Livermore National Lab., CA (United States); Holman, J.P. [Southern Methodist Univ., Dallas, TX (United States). Dept. of Mechanical Engineering

1996-06-06

450

Analysis of heat transfer during quenching of a gear blank  

SciTech Connect

This paper presents experimental and numerical results for the quench of a gear blank in agitated and stagnant oil. Heat transfer within the gear blank is analyzed with a whole domain-optimizer technique inverse solution method, to calculate the time history at every point in the gear blank. The development of this procedure represents the first stage in an overall analysis of the quench process that will later include material phase transformations and deformation. The paper presents ten variations in setting up the inverse problem, to analyze which combination of independent variables and decision variables results in the best match between experimental and numerical results. The results indicate that dividing the boundary of the gear blank into four zones and assigning a fixed heat transfer coefficient or heat flux to each zone yields an average RMS error (average difference between experimental and numerical results) of the order of 40 K. This error can be reduced by either increasing the number of zones, by reducing the number of thermocouples being matched, or by allowing the heat transfer or heat flux to vary within the zones. Of these possibilities, variation of heat transfer within the zones gives the best improvement in the quality of the match for the amount of extra effort required to run the problem.

Aceves, S M; Sahai, V

1999-03-01

451

Heat transfer and lance clogging during submerged powder injection  

NASA Astrophysics Data System (ADS)

Nitrogen and silica particles of 30, 130, and 450 ?m average diameters were injected at solid-to-gas loadings up to 280 kg/m3 into liquid lead at 400C through a steel lance equipped with four thermo-couples. The lance was positioned adjacent to a transparent wall in the lead retort so that the flow patterns could be photographed. It was found that 130 and 450 ?m particle injection produced bubling in the lead and clogging at high loadings, while the 30 ?m particles produced jetting with no clogging. Analysis of the thermocouple responses permitted the determination of the heat transfer coefficients at the inner and outer lance surfaces. The inner surface heat transfer coefficient increased with loading, whereas the one at the outer surface was independent of loading. A two-phase, unsteady-state, one-dimensional model was developed for momentum and heat transfer in the lance permitting the calculation of gas and particle velocities, volume fractions, and temperatures as well as the lance temperatures. Using the experimentally determined heat transfer coefficients, it is shown that the gas and particles are heated only 20 to 40 K in the lance. Nevertheless, this is a large heat demand which chills the lance so that clogging will occur in the bubbling regime.

Irons, G. A.

1987-03-01

452

On heat transfer at microscale with implications for microactuator design  

NASA Astrophysics Data System (ADS)

The dominance of conduction and the negligible effect of gravity, and hence free convection, are verified in the case of microscale heat sources surrounded by air at atmospheric pressure. A list of temperature-dependent heat transfer coefficients is provided. In contrast to previous approaches based on free convection, supplied coefficients converge with increasing temperature. Instead of creating a new external function for the definition of boundary conditions via conductive heat transfer, convective thin film coefficients already embedded in commercial finite element software are utilized under a constant heat flux condition. This facilitates direct implementation of coefficients, i.e. the list supplied in this work can directly be plugged into commercial software. Finally, the following four-step methodology is proposed for modeling: (i) determination of the thermal time constant of a specific microactuator, (ii) determination of the boundary layer size corresponding to this time constant, (iii) extraction of the appropriate heat transfer coefficients from a list provided and (iv) application of these coefficients as boundary conditions in thermomechanical finite element simulations. An experimental procedure is established for the determination of the thermal time constant, the first step of the proposed methodology. Based on conduction, the proposed method provides a physically sound solution to heat transfer issues encountered in the modeling of thermal microactuators.

Ozsun, Ozgur; Alaca, B. Erdem; Yalcinkaya, Arda D.; Yilmaz, Mehmet; Zervas, Michalis; Leblebici, Yusuf

2009-04-01

453

Vapor locking and heat transfer of multiple layers  

SciTech Connect

The cryogenic stability of a superconducting magnet depends on the heat transfer characteristics of the liquid helium cooling channels. One of the factors which affects the heat transfer to the channel is the amount of vapor accumulated in the channel. It is especially important to design a large magnet with cooling channels large enough to ensure the recovery of a normal zone produced in the magnet following the mechanical disturbances. A study of the vapor formation and heat transfer of multiple layers under both steady state and transient conditions is presented. The change in capacitance between the two sides of the heated channel is measured to determine the volume fraction of the vapor in the cooling channel. It is found that the heat transfer characteristics depend on the vapor accumulation and the velocity of vapor flow. The vapor locking heat flux is decreased when the vapor accumulation is increased. The samples were made to simulate the real cryostable superconductor and the cooling channels to be used in the large MHD superconducting magnet, designated as CFFF-SCMS, currently under construction at Argonne National Laboratory (ANL). (WHK)

Chen, C.J.; Wang, S.T.; Dawson, J.W.

1980-01-01

454

Heat transfer enhancement from enclosed discrete components using pinfin heat sinks  

Microsoft Academic Search

Computational modeling, temperature measurements, and flow visualizations were conducted to investigate the enhancement of combined natural convection, conduction, and radiation heat transfer from a 25.4mm25.4 mm discrete heat source in a 127mm127mm and 41.3 mm high enclosure, using pinfin heat sinks. The pinfin array was attached to the heated component, which was flush mounted on the enclosure base. Effects of

Enchao Yu; Yogendra Joshi

2002-01-01

455

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

Microsoft Academic Search

In the present study, the heat transfer characteristics in dry surface conditions of a new type of heat exchanger, namely\\u000a a helically coiled finned tube heat exchanger, is experimentally investigated. The test section, which is a helically coiled\\u000a fined tube heat exchanger, consists of a shell and a helical coil unit. The helical coil unit consists of four concentric\\u000a helically

Kwanchanok Srisawad; Somchai Wongwises

2009-01-01

456

Preliminary Heat Transfer Studies for the Double Shell Tanks (DST) Transfer Piping  

SciTech Connect

Heat transfer studies were made to determine the thermal characteristics of double-shell tank transfer piping under both transient and steady-state conditions. A number of design and operation options were evaluated for this piping system which is in its early design phase.

HECHT, S.L.

2000-02-15

457

Preliminary Heat Transfer Studies for the Double Shell Tanks (DST) Transfer Piping  

Microsoft Academic Search

Heat transfer studies were made to determine the thermal characteristics of double-shell tank transfer piping under both transient and steady-state conditions. A number of design and operation options were evaluated for this piping system which is in its early design phase.

2000-01-01

458

Heat transfer and instrumentation studies on rotating turbine blades in a transient facility  

NASA Astrophysics Data System (ADS)

The current demands of modern aviation have encouraged engine manufacturers to develop larger, more powerful, yet quieter and more fuel efficient gas turbine engines. This has promoted particular interest in the heat loads borne by turbines, for efficiency can be improved if turbine entry temperature is increased. Presently, ceilings for this parameter are set by the thermal properties of the blade materials and their internal cooling capabilities. It has been established that flow unsteadiness and secondary flows in the turbine passages greatly influence the heat transfer rate on turbine blades and endwall surfaces. The three-dimensionality of the rotating turbine flowfield, however, complicates the interaction of these unsteady effects and their combined role in heat transfer on turbine blades. To fulfill the need to study this complex fluid environment, a model turbine stage has been installed in the working section of the Isentropic Light Piston Tunnel at Oxford. This transient facility enables the rotor to be operated at engine representative conditions. Novel high density instrumentation has been development for use on the turbine blade. Both the production and calibration of the thin film gauges will be explained and the theory supporting heat transfer measurement using this instrumentation is presented in this thesis. Perhaps the most important feature of this thesis lies in the extensive mean and unsteady heat transfer rates measured on the blade profile. These were determined on a total of 5 streamlines and represent a significant contribution to the total experimental data available on 3-dimensional profiles at engine representative conditions.

Allan, William D. E.

1990-08-01

459

Stagnation point flow and heat transfer under free-steam turbulence  

NASA Astrophysics Data System (ADS)

Stagnation point flow and heat transfer in the presence of free-stream turbulence is investigated through both numerical simulation and theoretical analysis. Large eddy simulations (LES), using fourth order finite differences in curvilinear coordinates in conjunction with an efficient linearized dual-time snub-iteration scheme, are performed to study free-stream turbulence impingement, upon an elliptical leading edge and the resulting heat transfer enhancement. A new blending procedure is developed through which independent, statistically identical realizations of homogeneous isotropic turbulence are combined to provide realistic representations of the free-stream turbulence. Results for different free-stream turbulence intensity, length scale, and Mach number are presented. Turbulence statistics and Reynolds stress budget at different streamwise locations are examined in detail. It is found that small scale, intense vortical structures generated by vortex stretching near the leading edge are directly responsible for the elevated heat transfer. The numerical results on the heat transfer enhancement show good agreement with the experimental measurements. In the theoretical study, the distortion of three dimensional unsteady disturbances in an incompressible Hiemenz boundary layer and its effects on heat, transfer are analyzed using linear vortex dynamics. An asymptotic expression for the vorticity evolution is obtained with explicit dependence on the length scale and frequency of the disturbance. It is shown that the vorticity amplification, and hence the heat transfer enhancement, increases with decreasing length scale, and the maximum value is found to be around five times the boundary layer thickness. Extending the analysis to free-stream turbulence, we derive a new scaling correlation for the relative heat transfer enhancement which incorporates turbulence intensity, integral length scale and mean flow Reynolds number. This correlation parameter is shown to reasonably collapse recent experimental data.

Xiong, Zhongmin

460

Determination of heat sources and heat transfer coefficient for two-dimensional heat flow numerical and experimental study  

Microsoft Academic Search

An experimental apparatus and a numerical method are presented to study the determination of both the location and the time-varying strength of point heat sources within a body from temperature boundary measurements. It is shown that the computed solutions of the inverse heat source problems (IHSPs) are correlated to the heat transfer coefficient on the boundary where the temperature sensors

Refahi Abou khachfe; Yvon Jarny

2001-01-01

461

Speckle photography in heat transfer studies  

Microsoft Academic Search

The line-of-sight speckle photography of trans- parent media is used for quantitative measurements of the instantaneous temperature elds in 3D unsteady ows. Both electronic and photographic methods are employed for specklegram recording. The subsequent specklegram treatment uses the Young's fringes method as well as cross-correlation analysis of small interrogation areas of the recordings. Experimental data for three dierent heat trans-

A. Asseban; M. Lallemand; N. Fomin; E. Lavinskaja; W. Merzkirch; D. Vitkin

2000-01-01

462

Heat transfer including radiation and slag particles evolution in MHD channel-I  

SciTech Connect

Accurate estimates of convective and radiative heat transfer in the magnetohydrodynamic channel are provided. Calculations performed for a base load-size channel indicate that heat transfer by gas radiation almost equals that by convection for smooth walls, and amounts to 70% as much as the convective heat transfer for rough walls. Carbon dioxide, water vapor, and potassium atoms are the principal participating gases. The evolution of slag particles by homogeneous nucleation and condensation is also investigated. The particle-size spectrum so computed is later utilized to analyze the radiation enhancement by slag particles in the MHD diffuser. The impact of the slag particle spectrum on the selection of a workable and design of an efficient seed collection system is discussed.

Im, K.H.; Ahluwalia, R.K.

1980-01-01

463

Investigation of the heat transfer in high temperature gas turbine vanes  

NASA Astrophysics Data System (ADS)

The demand for higher efficiency, higher temperature industrial gas turbines used for the combined cycle plants has increased. The key technology of such high-temperature gas turbines with a turbine inlet temperature of 1300 C is the development of reliable air-cooled turbine vanes and blades. The life prediction of such air-cooled turbine vanes is strongly dependent on an accurate prediction of the metal temperature. The problem of temperature prediction is essentially one of obtaining the convective heat transfer boundary conditions on the external and internal surfaces of the vane. In this paper, typical heat transfer data which are indispensable for the analysis, are presented. Improvement of the temperature prediction accuracy within 25 C, the final goal is sought by feeding the discrepancy between the cascade test and the analysis back into the fundamental heat transfer tests.

Sato, Tomohiko; Takeishi, Kenichiro

1987-05-01

464

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

NASA Astrophysics Data System (ADS)

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

Determan, W. R.; Lewis, Brian

465

Heat flux distribution model by sequential algorithm of inverse heat transfer for determining workpiece temperature in creep feed grinding  

Microsoft Academic Search

The purpose of this study is to determine the heat flux distribution and to estimate the workpiece temperature in creep feed grinding. The sequential algorithm of the inverse heat transfer was used for determining the heat flux distribution. The amount of heat flux to the workpiece, the energy partition and the convective heat transfer coefficients both at the front and

Hae-Ji Kim; Nam-Kyung Kim; Jae-Seob Kwak

2006-01-01

466

Heat transfer of ternary mixtures inside enhanced surface tubing  

Microsoft Academic Search

Two phase flow heat transfer parameters such as coefficient of heat transfer and pressure drop observed during condensation of ternary azeotropic refrigerant mixtures R-404A (R125\\/Rl34a\\/R143a:44\\/4\\/52), R-407B (R32\\/R125\\/R134a:10\\/70\\/20), R407C (R32\\/R125\\/R 134a:23\\/25\\/52) and R408A (R22\\/R125\\/R143a:46\\/7\\/47) are presented in this paper. Experiments showed that for Reynolds numbers higher than 3.00 E06, R-408A appears to have greater heat transfer rates than the other blends

S. M Sami; D. E Desjardins

2000-01-01

467

Experimental Study of Endwall Heat Transfer in a Linear Cascade  

NASA Astrophysics Data System (ADS)

The endwall heat transfer characteristics of forced flow past outlet guide vanes (OGVs) in a linear cascade have been investigated by using a liquid crystal thermography (LCT) method. Due to the special design of an OGV profile, the focus of this study is emphasized on the heat transfer patterns around the leading part of a vane. The Reynolds number is kept constant at 260,000. Two attack angles of the vane are considered. For ? = 0, the vane obstructs the incident flow like a bluff body and a remarkable flow separation phenomenon was noticed. For ? = 30, the vane is more "streamlined" with respect to the incoming flow and no obvious flow separation was observed. In general, the endwall heat transfer for ? = 0 is higher than that for ? = 30.

Wang, Lei; Sundn, Bengt; Chernoray, Valery; Abrahamsson, Hans

2012-11-01

468

Heat and mass transfer analysis of a desiccant dehumidifier matrix  

SciTech Connect

This report documents the SERI Single-Blow Test Facility's design, fabrication, and testing for characterizing desiccant dehumidifiers for solar cooling applications. The first test article, a silica-gel parallel-plate dehumidifier with highly uniform passages, was designed and fabricated. Transient heat and mass transfer data and pressure drop data across the dehumidifier were obtained. Available heat and mass transfer models were extended to the parallel-place geometry, and the experimental data were compared with model predictions. Pressure drop measurements were also compared with model predictions of the fully developed laminar flow theory. The comparisons between the lumped-capacitance model and the experimental data were satisfactory. The pressure drop data compared satisfactorily with the theory (within 15%). A solid-side resistance model that is more detailed and does not assume symmetrical diffusion in particles was recommended for performance. This study has increased our understanding of the heat and mass transfer in silica gel parallel-plate dehumidifiers.

Pesaran, A.A.

1986-07-01

469

Convective heat transfer around vertical jet fires: an experimental study.  

PubMed

The convection heat transfer phenomenon in vertical jet fires was experimentally analyzed. In these experiments, turbulent propane flames were generated in subsonic as well as sonic regimes. The experimental data demonstrated that the rate of convection heat transfer increases by increasing the length of the flame. Assuming the solid flame model, the convection heat transfer coefficient was calculated. Two equations in terms of adimensional numbers were developed. It was found out that the Nusselt number attains greater values for higher values of the Rayleigh and Reynolds numbers. On the other hand, the Froude number was analyzed only for the subsonic flames where the Nusselt number grows by this number and the diameter of the orifice. PMID:21962859

Kozanoglu, Bulent; Zrate, Luis; Gmez-Mares, Mercedes; Casal, Joaquim

2011-09-21

470

Heat transfer between two metallic surfaces at small distances  

NASA Astrophysics Data System (ADS)

In scanning thermal microscopy, but also in scanning tunneling microscopy, the thermal contact between tip and sample plays an important role. The heat transfer across the vacuum gap between two parallel metallic surfaces, if the gap width is decreased below several microns, has been investigated. At these distances propagating electromagnetic modes die out but simultaneously a transfer of nonpropagating surface modes across the gap becomes more probable. The heat conductance of the vacuum gap should become distance dependent and larger than that given by the Stefan-Boltzmann law; however, the experimental results and theoretical considerations indicate that the heat transfer, based on the discussed proximity mechanism, is very small, smaller than predicted by the theory of Polder and Van Hove.

Xu, J.-B.; Laeuger, K.; Moeller, R.; Dransfeld, K.; Wilson, I. H.

1994-12-01

471

FEHM: finite element heat and mass transfer code  

SciTech Connect

The finite element heat and mass (FEHM) transfer code is a computer code developed to simulate geothermal and hot dry rock reservoirs. It is also applicable to natural-state studies of geothermal systems and ground-water flow. It solves the equations of heat and mass transfer for multiphase flow in porous and permeable media using the finite element method. The code also has provisions for a noncoupled tracer; that is, the tracer solutions do not affect the heat and mass transfer solutions. It can simulate two-dimensional, two-dimensional radial, or three-dimensional geometries. A summary of the equations in the model, the numerical solution procedure, and model verification and validation are provided in this report. A user's guide and sample problems are included in the appendices. 17 refs., 10 figs., 4 tabs.

Zyvoloski, G.; Dash, Z.; Kelkar, S.

1988-03-01

472

Nuclear reactor fuel element having improved heat transfer  

DOEpatents

A nuclear reactor fuel element having improved heat transfer between fuel material and cladding is described. The element consists of an outer cladding tube divided into an upper fuel section containing a central core of fissionable or mixed fissionable and fertile fuel material, slightly smaller in diameter than the inner surface of the cladding tube and a small lower accumulator section, the cladding tube being which is filled with a low molecular weight gas to transfer heat from fuel material to cladding during irradiation. A plurality of essentially vertical grooves in the fuel section extend downward and communicate with the accumulator section. The radial depth of the grooves is sufficient to provide a thermal gradient between the hot fuel surface and the relatively cooler cladding surface to allow thermal segregation to take place between the low molecular weight heat transfer gas and high molecular weight fission product gases produced by the fuel material during irradiation.

Garnier, J.E.; Begej, S.; Williford, R.E.; Christensen, J.A.

1982-03-03

473

Free shear layer and swirl flow heat transfer enhancement  

NASA Astrophysics Data System (ADS)

Two wall shape induced convective heat transfer enhancement mechanisms for channel flows are investigated. The first uses transverse grooves in the channel wall to produce unstable free shear layers which cause traveling waves to be superimposed on the channel mean flow, thus augmenting heat transfer. The onset of natural oscillations are observed at a channel Reynolds number of 630, and they persist into the turbulent flow regime. Heat transfer measurements show augmentation for Reynolds numbers between 1500 and 5000. The second technique uses streamline curvature to produce a steady swirling flow in a serpentine channel. Flow visualization shows that the secondary flow consists of pairs of counter-rotating axial rolls which form adjacent to the upper and lower channel boundaries and sweep fluid into the core of the flow.

Wirtz, R. A.; Greiner, M.; Snyder, B.; Turner, R.

1988-09-01

474

Heat transfer during the boiling of acetone and ethyl alcohol in a thermosiphon with porous capillary structures on the heat-transfer face  

Microsoft Academic Search

It is shown experimentally that heat transfer during boiling on a 0.004-m-diameter heat-transfer surface of a thermosiphon conforms to the rules established for the case of boiling in a large volume. The heat transfer is shown to become unstable in the presence of brass screens on the heat-transfer surface. Considerable intensification and stabilization of the boiling process are achieved by

V. G. Kashirskii; Iu. Ia. Pechenegov; Iu. I. Serov

1983-01-01

475

Intercomparison of efficiency transfer software for gamma-ray spectrometry  

Microsoft Academic Search

The EUROMET project 428 examines efficiency transfer results for Ge gamma-ray spectrometers when the efficiency is known for a reference point source geometry. For this, different methods are used, such as Monte Carlo simulation or semi-empirical computation. The exercise compares the application of these methods to the same selected experimental cases to determine the usage limitations versus the requested accuracy.