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Showing papers on "Heat transfer coefficient published in 1981"


Journal ArticleDOI
TL;DR: In this paper, numerical heat transfer and fluid flow are used to transfer heat from a nuclear power plant to a nuclear fluid flow system, and the resulting fluid flow is used for nuclear power plants.
Abstract: (1981). Numerical Heat Transfer and Fluid Flow. Nuclear Science and Engineering: Vol. 78, No. 2, pp. 196-197.

3,386 citations


Journal ArticleDOI
TL;DR: In this paper, a theory is proposed which describes the transfer process of momentum and heat in a two-phase bubble flow in channels, and the eddy diffusivity to express the turbulent structure of the liquid phase is subdivided into the two components, one for the inherent wall turbulence independent of bubble agitation and the other for the additional turbulence caused by bubbles.

489 citations


01 Jan 1981
TL;DR: In this article, the authors developed composite relations for the variation of the heat transfer coefficient along the plate surfaces, and the mathematical development and verification of such composite relations as well as the formulation and solution of the optimizing equations for the various boundary conditions of interest constitute the core of the presentation.
Abstract: While component dissipation patterns and system operating modes vary widely, many electronic packaging configurations can be modeled by symmetrically or asymmetrically isothermal or isoflux plates. The idealized configurations are amenable to analytic optimization based on maximizing total heat transfer per unit volume or unit primary area. To achieve this anlaytic optimization, however, it is necessary to develop composite relations for the variation of the heat transfer coefficient along the plate surfaces. The mathematical development and verification of such composite relations as well as the formulation and solution of the optimizing equations for the various boundary conditions of interest constitute the core of this presentation.

481 citations


Journal ArticleDOI
TL;DR: In this article, two-dimensional arrays of circular jets of air impinging on a heat transfer surface parallel to the jet orifice plate are considered, and the air is constrained to exit in a single direction along the channel formed by the surface and the jet plate.
Abstract: Two-dimensional arrays of circular jets of air impinging on a heat transfer surface parallel to the jet orifice plate are considered. The air, after impingement, is constrained to exit in a single direction along the channel formed by the surface and the jet plate. The downstream jets are subjected to a crossflow originating from the upstream jets. Experimental and theoretical results obtained for streamwise distributions of jet and crossflow velocities are presented and compared. Measured Nusselt numbers resolved to one streamwise hole spacing are correlated with individual spanwise row jet Reynolds numbers and crossflow-to-jet velocity ratios. Correlations are presented for both inline and staggered hole patterns including effects of geometric parameters: streamwise hole spacing, spanwise hole spacing, and channel height, normalized by hole diameter. The physical mechanisms influencing heat transfer coefficients as a function of flow distribution and geometric parameters are also discussed.

314 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present techniques and theories covering the design and management of thermal energy storage systems in the areas of heat recovery and in circumstances where energy availability does not coincide chronologically with demand are presented.
Abstract: The newest techniques and theories covering the design and management of thermal energy storage systems in the areas of heat recovery and in circumstances where energy availability does not coincide chronologically with demand are presented. Techniques that predict the performance of sensible heat storage units in a broad range of operating conditions and methods for designing energy storage units for a variety of applications are covered comprehensively. The single blow problem of gas passing through heat-storing packing continuously in one direction is discussed. Solutions to this problem facilitate the control of the drying or cooling of beds of grain, other food stuffs, and industrial granular or powder products. These same solutions are applicable to the crucial issues of heat storage capabilities of particular construction in buildings and thermal stores built into solar collectors. Detailed information is included about counterflow regenerators including finite conductivity and nonlinear models. New concepts in computational methodology, parallel flow regenerators, heat storage exchangers, and packed beds are also covered. The optimization of prediction of heat storage systems and useful engineering correlations for thermal and hydraulic aspects of storage unit design are presented and explained in detail.

214 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of Gr (Grashof number), Gm (modified Grashof numbers) and permeability K of the porous medium on the velocity and rate of heat transfer are discussed when the surface is subjected to a constant suction velocity.

119 citations


Journal ArticleDOI
TL;DR: In this article, a simple mathematical model is developed to predict the performance of a two-phase closed thermosyphon, where water, ethanol and Freon 113 are used as the working fluids.

117 citations


Journal ArticleDOI
TL;DR: In this article, the effect of the choice of shape and dimensions of the air flow passages in plate-type, air-heating solar collectors is assessed, and their effect on the overall heat transfer coefficient between the air stream and the plate is discussed.
Abstract: The effect of the choice of shape and dimensions of the air flow passages in plate-type, air-heating solar collectors is assessed. Particular examination is made of their effect on the overall heat transfer coefficient between the air stream and the plate, which has an important effect on collector efficiency. It is emphasized in this study that in comparing various designs of flow passage, they should be compared for the same pressure drop suffered by the air in passing through the collector, and for the same mass flow rate m per unit of collector area. 11 refs.

114 citations


Journal ArticleDOI
TL;DR: In this article, an analysis of the flow and heat transfer in an interrupted-plate passage, which is an idealization of the offset-fin heat exchanger, is presented, where the plates are considered to be of finite thickness.

102 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the influence of layering on the relationship between the rate of heat loss from and heat supply to a number of convecting layers of different viscosity and thicknesses.
Abstract: Parameterized convective schemes for constant viscosity fluids are used to investigate the influence of layering on the relationship between the rate of heat loss from and heat supply to a number of convecting layers of different viscosity and thicknesses Simple analytic expressions are obtained which accurately predict the behavior to a step decrease in the heat supply, and show that layering considerably increases the response time The same arguments are applied to a planet consisting of spherical shells They show that the response of the earth's heat loss to the decay of radioactive elements depends strongly on whether or not mantle convection extends from the core to the surface If it does so, the surface heat flux is only about 50% greater than the heat generation rate However if upper and lower mantle convection occurs in two separate shells, as seismological and geochemical arguments suggest, the response time is increased The present surface heat flux is then principally controlled by the thermal structure of the earth at the time it was formed The best estimate of the present ratio of the heat loss to heat generation is about two, and this value is consistent with the behavior of an earth model consisting of a two-layered mantle overlying a core

102 citations


Journal ArticleDOI
TL;DR: The wall heat transfer coefficient of the gas-liquid-solid fluidized beds in the range of stable fluidization state runs correlated as a function of modified Nusselt number, modified Reynolds number and gas phase Froude number as discussed by the authors.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the relationship between the pressure drop and the volumetric heat transfer between the air and the rockbeds in low temperature storage applications and found that both the pressure and heat transfer coefficient depend upon the rock size and the air flow rate.

Journal ArticleDOI
TL;DR: In this article, the effects of G (Grashof number) and K (permeability parameter) on the velocity and the rate of heat transfer of two-dimensional free convection flow through a porous medium bounded by a vertical infinite surface is considered.
Abstract: Steady two-dimensional free convection flow through a porous medium bounded by a vertical infinite surface is considered. Expressions for the velocity, temperature and the rate of heat transfer are obtained. Effects of G (Grashof number) and K (permeability parameter) on the velocity and the rate of heat transfer are discussed.

Journal ArticleDOI
TL;DR: In this article, a two-phase air-water bubble flow is investigated experimentally to confirm the applicability of the theoretical model proposed in Part 1, and the results for bubble flow simulation are presented to clarify the interrelationship of the frictional pressure gradient and the heat transfer coefficient with the void fraction profile.

Journal ArticleDOI
TL;DR: In this article, the entrainment or flooding limit of a copper-water thermosyphon was investigated in more detail, and the experimental results have been assessed and compared with existing theories.


Journal ArticleDOI
TL;DR: In this article, the authors studied the relationship between overall heat transfer and the degrees of thermal stratification on both sides of the partition and showed that the theoretical Nusselt number calculation is in good agreement with experimental measurements.


Journal ArticleDOI
TL;DR: In this paper, the effect of specimen and bath temperature on the failure of brittle ceramics in a thermal quench experiment was studied by quenching glass and alumina rods in water and silicon oil baths at different temperatures.
Abstract: The effect of specimen and bath temperature on the failure of brittle ceramics in a thermal quench experiment was studied by quenching glass and alumina rods in water and silicon oil baths at different temperatures. The results were discussed in terms of the variation of heat transfer coefficient of the quenching media and the change in material properties as a function of temperature. It was found that the usual assumption of constant heat transfer coefficient and material properties may lead to considerable errors in the quantitative interpretation of the results of thermal quench experiments. Effective values for the film coefficient of heat transfer for water and oil baths were estimated as a function of film temperature from thermal quench data. Recommendations were made for the selection of quenching media and for the procedure to be followed in reporting the results.

Journal ArticleDOI
TL;DR: In this article, the authors present a series solution for the local surface temperature history for a semi-infinite body heated only over a circular region, where inside this region the heat flux is constant with time and position while outside the circular area the surface is insulated.

Journal ArticleDOI
TL;DR: In this article, the local heat transfer coefficients during condensation of pure vapour inside a horizontal tube were investigated and the results showed that approximately 800 LO of heat transfer coefficient was achieved.

01 Jan 1981
TL;DR: In this paper, an additive mechanism of convective and boiling heat transfer has been formulated to give the net heat transfer during flow boiling, which employs three dimensionless parameters: the Convection number, the Boiling number and the Froude number.
Abstract: This thesis is concerned with an investigation carried out to establish a new correlation for the prediction of the heat transfer coefficient during flow boiling through tubes, vertical and horizontal flows, for water and organic fluids (including refrigerants). An additive mechanism of convective and boiling heat transfer has been formulated to give the net heat transfer during flow boiling. The correlation employs three dimensionless parameters: the Convection number, the Boiling number and the Froude number. The correlation has been tested with the data (over 500) from twelve experimental cases of six investigators and the mean deviation from the measured values of the heat transfer coefficients has been found to be + 13%.

Journal ArticleDOI
TL;DR: In this paper, the effect of the variation of physical properties on heat transfer in pipe flow for liquid metals has been investigated and the results of heat transfer calculation were compared with experimental data when available.

01 Jan 1981
TL;DR: In this paper, the heat transfer coefficients for circular offices and impinging on a surface parallel to the jet orifice plate were investigated. But the authors focused on the impact of the orifice on the surface of the office.
Abstract: Correlations for heat transfer coefficients for jets of circular offices and impinging on a surface parallel to the jet orifice plate are presented. The air, following impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the heat transfer (impingement) surface. The downstream jets are subjected to a crossflow originating from the upstream jets. Impingement surface heat transfer coefficients resolved to one streamwise jet orifice spacing, averaged across the channel span, are correlated with the associated individual spanwise orifice row jet and crossflow velocities, and with the geometric parameters.


Journal ArticleDOI
TL;DR: In this paper, the power consumption of an impeller in a stirred tank as well as the inside film heat transfer coefficient was determined for turbine, Pfaudler and anchor impellers.


Journal ArticleDOI
Abstract: The thermal heat flux along a uniform magnetic field due to a temperature gradient is calculated using a Monte Carlo solution to the Fokker–Planck equation. This numerical solution, which is computed for a particular electron temperature profile, is valid for arbitrary mean‐free‐path, λmfp. The calculated heat flux makes a smooth transition between the analytic expressions for the short and long λmfp limits.

Journal ArticleDOI
TL;DR: In this paper, a numerical study has been made of steady-state free convective heat transfer from a solid sphere to an incompressible Newtonian fluid for Grashof numbers of 0.05, 1,10,25 and 50 for a Prandtl number of0.72.

Journal ArticleDOI
TL;DR: In this article, the authors present experimental results on heat transfer and hydrodynamics in film condensation of a stagnant pure vapour on vertical short surfaces in an electric field of different strength, frequency and uniformity.