Showing papers on "Heat transfer published in 1978"
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01 Jan 1978
TL;DR: In this article, the authors present the following principles: Momentum Transfer and Overall Balances, Steady State Heat Transfer, Unsteady State and Convective Mass Transfer, and Mass Transfer.
Abstract: I. TRANSPORT PROCESSES: MOMENTUM, HEAT, AND MASS. 1. Introduction to Engineering Principles and Units. 2. Principles of Momentum Transfer and Overall Balances. 3. Principles of Momentum Transfer and Applications. 4. Principles of Steady-State Heat Transfer. 5. Principles of Unsteady-State Heat Transfer. 6. Principles of Mass Transfer. 7. Principles of Unsteady-State and Convective Mass Transfer. II. UNIT OPERATIONS. 8. Evaporation. 9. Drying of Process Materials. 10. Stage and Continuous Gas-Liquid Separation Processes. 11. Vapor-Liquid Separation Processes. 12. Liquid-Liquid and Liquid-Solid Separation Processes. 13. Membrane Separation Processes. 14. Mechanical-Physical Separation Processes. III. APPENDICES. A1. Fundamental Constants and Conversion Factors. A2. Physical Properties of Water. A3. Physical Properties of Inorganic and Organic Compounds. A4. Physical Properties of Foods and Biological Materials. A5. Properties of Pipes, Tubes, and Screens. Notation. Index.
1,423 citations
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TL;DR: In this paper, the authors derived formulas for the electron thermal conductivity in the collisional and collisionless limits for the case of destroyed magnetic surfaces and showed that these formulas can be used to derive a collision-free model of the electron conductivity.
Abstract: Formulas for the electron thermal conductivity have been derived in the collisional and collisionless limits for the case of destroyed magnetic surfaces.
1,128 citations
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TL;DR: In this article, the published heat transfer data obtained from steady and nonsteady measurements are corrected for the axial fluid thermal dispersion coefficient values proposed by Wakao and Funazkri.
993 citations
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01 Jun 1978
TL;DR: In this article, the authors introduce solar energy conversion, thermal energy storage and transport, and photovoltaics for capturing solar energy through biomass, and economic analysis.
Abstract: 1. Introduction to Solar Energy Conversion 2. Fundamentals of Solar Radiation 3. Methods of Solar Collection and Thermal Conversion 4. Thermal Energy Storage and Transport 5. Solar-Heating Systems 6. Solar Cooling and Dehumidification 7. Passive Methods for Heating, Cooling and Daylighting 8. Solar Thermal Power and Process Heat 9. Photovoltaics 10. Solar Photochemical Applications 11. Capturing Solar Energy through Biomass 12. Introduction to Economic Analysis
960 citations
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TL;DR: In this article, a quantitative analysis of particle to fluid heat transfer on the basis of a stochastic model of the fixed bed leads to a constant value of the Nusselt group at low Reynolds number.
933 citations
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TL;DR: In this article, a more realistic model is developed, based on the idea that the thermal structure of the plate becomes unstable and leads to the development of small-scale convection, which then supplies the heat flux needed to match the observations rather than an artificial constant temperature boundary condition.
Abstract: Though a simple thermal model of plate creation matches the observed bathymetry and heat flow with considerable accuracy, it only does so because a constant temperature is imposed as a lower boundary condition. A more realistic model is developed here, based on the idea that the thermal structure of the plate becomes unstable and leads to the development of small-scale convection. Convective heat transport then supplies the heat flux needed to match the observations rather than an artificial constant temperature boundary condition. The temperature dependence of the rheology is represented in a simple manner. Below a given temperature the material is assumed to move rigidly, defining an upper mechanical boundary layer. Beneath this rigid layer, where the temperatures are greater, the material is assumed to have a constant Newtonian viscosity. The part of the viscous region where there are significant vertical temperature gradients, immediately below the mechanical boundary layer, forms a thermal boundary layer. As the plate cools, both the mechanical and thermal boundary layers increase in thickness. A local critical Rayleigh number criterion is used to test the stability of the thermal boundary layer. On this basis a convective instability is predicted, its occurrence coinciding with the breakdown of the linear dependence of the depth of the ocean floor on the square root of age. Though the small-scale convection which develops from this instability modifies the thermal structure, the basic observational constraints are shown to be satisfied. The stability criterion is further tested in two different laboratory experiments. These experiments also illustrate a possible form for the instability, with cold dense material breaking away from the base of the plate and being replaced by hotter material from below. The effects of the cooling of the oceanic plate as it moves away from a midocean ridge have received a good deal of attention, both theoretical and observational. Forsyth [1977] recently reviewed the different measurements that have been made. Variations in mean heat flow, depth, and velocity of ! -
519 citations
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TL;DR: In this article, the effects of rib shape, angle of attack and pitch-to-height ratio on friction factor and heat transfer were investigated on a rib-roughened surface.
512 citations
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TL;DR: In this paper, the authors describe a thermal heat pump consisting of a heat pipe, in which the vapor passage located for heat dissipation between the Warmeubertragungszone for heat supply and the WARMEBERTRTAGZENzone (16) changing an over its length, has the flow velocity of the vapor, first increasing and then degrading cross-section and in which in the area of increased vapor velocity another warmeubertraagung zone with heat supply or removal is the increased vapor velocities may be subsonic or supersonic range.
Abstract: The invention relates to a thermal heat pump. consisting of a heat pipe (11). in which the vapor passage located for heat dissipation between the Warmeubertragungszone for heat supply and the Warmeubertragungszone (16) changing an over its length, has the flow velocity of the vapor, first increasing and then degrading cross-section and in which in the area of the increased vapor velocity another Warmeubertragungszone with heat supply or removal is the increased vapor velocity may be subsonic or supersonic range. The cross-sectional change of the vapor channel (16) in the heat pipe (11) between the two outer heat transfer zones is advantageously carried out by a displacement body (13) effected with the particular surface contour.
292 citations
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TL;DR: In this paper, the phase change in transient non-linear heat conduction problems is solved using quadratic isoparametric elements and it is demonstrated that very good accuracy may be achieved.
Abstract: The algorithm in a earlier paper by Comini et al1 for handling the phase change in transient non-linear heat conduction problems is simplified and improved. Two examples involving phase change are solved using quadratic isoparametric elements and it is demonstrated that very good accuracy may be achieved.
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TL;DR: In this paper, a mathematical model for water transfer in concrete above 100°C is developed, and the pore volume available to free water increases as dehydration due to heating progresses and as pore pressure is increased.
Abstract: A mathematical model for water transfer in concrete above 100°C is developed. Drying tests of heated concrete are reported and material parameters of the model are identified from these tests as well as other test data available in the literature. It is found that water transfer is governed principally by the gradient of pore pressure, which represents the pressure in vapor if concrete is not saturated. Permeability is found to increase about 200 times as temperature passes 100°C, which could be explained by a loss of necks on migration passages. The pore volume available to free water increases as dehydration due to heating progresses and as the pore pressure is increased. The temperature effect on pressure-water content (sorption) relations is determined. Thermodynamic properties of water are used to calculate pore pressures. A finite element program for coupled water and heat transfer is developed and validated by fitting test data.
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TL;DR: In this article, a three-dimensional model for calculating the distribution of velocity, temperature, and pollutant concentration in open channel flows, and a depth-averaged two-dimensional version for situations with insignificant stratification and secondary currents are presented.
Abstract: The paper describes a three-dimensional model for calculating the distribution of velocity, temperature, and pollutant concentration in open channel flows, and a depth-averaged two-dimensional version for situations with insignificant stratification and secondary currents. Both models are restricted to parabolic flows where influences cannot be transmitted upstream. The turbulent stresses and heat/concentration fluxes appearing in these equations are determined from the so-called k-ϵ turbulence model that solves differential transport equations for the turbulence kinetic energy k and the rate of its dissipation ϵ. In the depth-averaged model, the bottom shear stress, surface heat flux and turbulence production due to bottom shear are accounted for by source/sink terms in the relevant equations. The 3D calculations compare favorably with available measurements. The 2D and 3D predictions agree well for high Froude numbers; for a Froude number of 5 they agree only for the rough bed, while for the smooth bed they start to deviate significantly at a Froude number of 10.
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TL;DR: In this article, the authors proposed a combination of the combined parameter, equation (16), specific heat at constant pressure, friction factor, mass velocity, mass flow rate, Reynolds number, number of entropy production units, and number of heat transfer units.
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01 Jan 1978
Abstract: 1 Introduction And The First Law Of Thermodynamics 2 The Working Fluid 3 Reversible And Irreversible Processes 4 The Second Law 5 The Heat Engine Cycle 6 Mixtures 7 Combustion 8 Steam Cycles 9 Gas Turbine Cycles 10 Nozzles And Jet Propulsion 11 Rotodynamic Machinery 12 Positive Displacement Machines 13 Reciprocating Internal-Combustion Engines 14 Refrigeration And Heat Pumps 15 Psychometry And Air-Conditioning 16 Heat Transfer 17 The Sources, Use And Management Of Energy
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TL;DR: In this paper, temperature and velocity fields in a round heated jet were investigated in detail, both conventional measurements and conditional measurements (zone averages and point averages) were performed, and the probability density functions of the lengths of turbulent and non-turbulent durations were also measured.
Abstract: The temperature and velocity fields in a round heated jet were investigated in detail. Both conventional measurements and conditional measurements (zone averages and point averages) were performed. The probability density functions of the lengths of turbulent and non-turbulent durations were also measured. Filtered correlation measurements show that large-scale turbulent motions were responsible for the bulk of momentum and heat transport, and also that small scales were more efficient in transporting heat than in transporting momentum. In no case was heat transported further or more than momentum, however. These results are discussed in detail, particularly with regard to the entrainment. Conservation equations for turbulent-zone variables and the intermittency factor are derived and a model for some of the resulting higher-order correlations is suggested. An exact equation for the intermittency function is presented.
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TL;DR: In this article, the quenching of 19 and 25.4 mm spheres of steel, copper, and silver by water in natural and forced flow has been studied experimentally and theoretically.
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TL;DR: In this article, an experimental and numerical study has been made on convective heat transfer in coiled tubes for two boundary conditions: for a uniform peripherally averaged heat flux and for a constant wall temperature.
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TL;DR: In this paper, the effects of storage capacity, storage unit heat transfer characteristics, collector area and location on the system performance are investigated for systems utilizing sodium sulfate decahydrate and paraffin wax as storage media.
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TL;DR: In this paper, the critical heat flux (CHF) in the conditions that the fluid fed to heated tubes is subcooled (including saturated liquid in the extreme situation) with no entrained vapor was investigated.
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TL;DR: In this article, a distortion parameter of liquid films, which is a ratio of an allowable difference in surface tension to the dynamic pressure of uniform film flow, is derived for each laminar and turbulent film flow.
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TL;DR: In this paper, the authors measured the heat transfer to simulated (porous sphere) water and methanol droplets in an atmospheric vertical hot air tunnel with a Reynolds number range of 200-2000, a free stream air temperature range of 150-960°C and a velocity range of 2.1-11.4 m/s.
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TL;DR: In this paper, the thermal state of the Earth accumulating from solid bodies is investigated for a growing spherically symmetrical planet which takes into account heating by impacts of bodies, by radioactivity, and by compression of its material.
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TL;DR: A simple parameterization scheme has been developed in terms of which the energetically important effects of convective heat transfer may be included in an energy balance model of the thermal history of a planet as mentioned in this paper.
Abstract: A simple parameterization scheme has been developed in terms of which the energetically important effects of convective heat transfer may be included in an energy balance model of the thermal history of a planet. The scheme is illustrated in the context of a discussion of the thermal history of the Earth in which mantle wide convection is assumed and the internal energy is completely primordial. The observed mean mantle viscosity from postglacial rebound strongly constrains the model.
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TL;DR: In this paper, Bartz, D. R., E. G., and E. O. Blottner, F. M. Smith, A. P. Hartnett, and T. F. Irvine Jr. present a simple equation for estimating the velocity of a Rocket Nozzle convective heat transfer coefficient.
Abstract: References ^artz, D. R., "A Simple Equation for Rapid Estimation of Rocket Nozzle Convective Heat Transfer Coefficients," Jet Propulsion, Vol. 27, Jan. 1957, pp. 49-51. Bartz, D. R., "Heat Transfer from Rapidly Accelerating Flows," in Advances in Heat Transfer, edited by J. P. Hartnett and T. F. Irvine Jr., Vol. 2, Academic Press, New York, 1965. Cebecci, T. and Smith, A. M. O., Analysis of Turbulent Boundary Layers, Academic Press, New York, 1974. Eckert, E. R. G., Analysis of Heat and Mass Transfer, McGfaw Hill, New York, 1972. Blottner, F. G., ''Finite Difference Methods of Solution of the Boundary Layer Equations," AIAA Journal, Vol. 8, Feb. 1970, pp. 193-205.
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TL;DR: In this article, a treatment of sensible-heat energy storage units as systems intended to store useful work is presented, and an analysis of the thermodynamic irreversibilities associated with storing energy from a hot gas source as sensible heat in huge liquid baths is presented.
Abstract: The paper presents a treatment of sensible-heat energy storage units as systems intended to store useful work. An analysis of the thermodynamic irreversibilities associated with storing energy from a hot gas source as sensible heat in huge liquid baths points out two important trade-offs. First, there exists an optimum well-defined quantity of hot gas to be used in order to maximize the useful work stored in the liquid bath. Using more than this optimum quantity in the hope of maximizing the amount of thermal energy stored as sensible heat leads to severe thermodynamics losses. Second, there exists an optimum relationship among the gas-liquid heat-exchanger design parameters which minimizes the system irreversibility while maximizing its capability of storing useful work. This relationship provides a procedure for estimating the heat-exchanger optimum number of transfer units. The existence of the two optima demonstrates that designing sensible heat units for maximum thermal energy storage does not necessarily amount to thermodynamically optimizing such systems.
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TL;DR: In this article, a simplified formulation is presented to deal with interfacial stability problems with mass and heat transfer for Rayleigh-Taylor stability problems of a liquid-vapor system, and it is found that the effect of mass transfer tends to enhance the stability of the system when the vapor is hotter than the liquid, although the classical stability criterion is still valid.
Abstract: A simplified formulation is presented to deal with interfacial stability problems with mass and heat transfer. For Rayleigh–Taylor stability problems of a liquid‐vapor system, it is found that the effect of mass and heat transfer tends to enhance the stability of the system when the vapor is hotter than the liquid, although the classical stability criterion is still valid. For Kelvin–Helmholtz stability problems, however, the classical stability criterion is found to be substantially modified due to the effect of mass and heat transfer.
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01 Jan 1978