Showing papers on "Heat transfer published in 1970"
TL;DR: In this article, the authors discuss heat transfer and skin friction in turbulent pipe flow with variable physical properties and highlight analytical methods to describe heat transfer mechanisms for constant liquid properties quite satisfactorily and to take into account the influence of the variation of physical properties with temperature versus heat transfer.
Abstract: Publisher Summary This chapter discusses heat transfer and skin friction in turbulent pipe flow with variable physical properties. The constant properties solution has been considered only so far as is necessary for the flow and heat transfer analysis with variable physical properties. The chapter highlights analytical methods to describe heat transfer mechanisms for constant liquid properties quite satisfactorily and to take into account the influence of the variation of physical properties with temperature versus heat transfer and skin friction in a number of important cases. Disagreement between theoretical and experimental results observed in other cases, in particular, with a considerable change in physical properties over the flow cross section, may be attributed to imperfect methods of estimating the effect of the variation of physical properties on turbulent diffusivity. Important experimental material has been accumulated on heat transfer and skin friction for variable physical properties. However, certain portions of this material possess relatively low accuracy that prevents its successful use. For a number of important cases, there has been no systematic data collection or that which is available is scanty and contradictory. Therefore, the need for further experimental investigations, with a high degree of accuracy, into the fluid mechanics and heat transfer for variable physical properties is quite urgent.
1,450 citations
TL;DR: In this article, the complex problem of void calculation in different regions of flow boiling is divided in two parts: the first part includes only the description of the mechanisms and the calculation of the rates of heat transfer for vapour and liquid.
637 citations
TL;DR: In this article, the transfer of heat and momentum by motion on the scale of cyclone waves and long waves is deduced from a knowledge of their mechanics, which is independent of notions of mixing but is similar to that for non-isotropic diffusion.
Abstract: The transfer of heat and momentum by motion on the scale of cyclone waves and long waves is deduced from a knowledge of their mechanics. The law of horizontal transfer of entropy is independent of notions of mixing but is similar to that for non-isotropic diffusion. The law accurately represents the annual variation of heat-flux in the Northern Hemisphere. Perturbation theory suggests realistic spatial variations for the transfer and provides a rational basis for calculating transfer coefficients which can then be used to find the flux of other conservative quantities. Most importantly the Equatorward flux of potential vorticity is well defined and is shown to determine the horizontal flux of momentum uv. The mean surface winds, and the mean meridional circulation (which is seen to be frictionally driven) are then determined. A model of the general circulation is defined by these properties, and this is integrated analytically for a simplified case and compared with motion observed in the Gulf Stream, the mesosphere, and dishpan experiments as well as the troposphere.
458 citations
305 citations
TL;DR: In this article, it was shown that large heat generation along the deep-earthquake fault zone and effective heat transfer in the upper mantle above the deep earthquake zone is required to explain the heat flow pattern across island arcs and marginal seas.
281 citations
01 Jan 1970
237 citations
219 citations
Book•
01 Jan 1970
TL;DR: In this article, the authors present a survey of thermal radiation in the context of heat transfer in furnaces, including the following categories: heat exchange between black surfaces, Heat exchange between grey surfaces, heat exchange among grey surfaces 5. Emission and absorption by gases.
Abstract: 1. Fundamentals of thermal radiation 2. View factors 3. Heat exchange between black surfaces 4. Heat exchange between grey surfaces 5. Emission and absorption by gases 6. Radiative heat transfer in furnaces 7. Combined modes of heat transfer 8. Measurement of temperature 9. Radiation from flames Further reading
193 citations
TL;DR: Experimental average heat transfer coefficients for free-convection cooling of arrays of isothermal fins on horizontal surfaces over a wider range of spacings than previously available are reported in this article.
Abstract: Experimental average heat-transfer coefficients for free-convection cooling of arrays of isothermal fins on horizontal surfaces over a wider range of spacings than previously available are reported. A simplified correlation is presented and a previously available correlation is questioned. An optimum arrangement for maximum heat transfer and a preliminary design method are suggested, including weight considerations.
177 citations
TL;DR: In this paper, the results of experimental investigations on natural-convection heat transfer from the outer surface of a vertical cylinder one metre high to water, spindle oil and Mobiltherm oil are described.
TL;DR: In this article, an approximation for solving the diffuse transmission and reflection problem when the phase function has a sharp forward peak was proposed. But the forward peak is truncated and compensated for by changing the volume scattering coefficient.
Abstract: We consider an approximation that is useful for solving the diffuse transmission and reflection problem when the phase function has a sharp forward peak. In this approximation the forward peak is truncated and compensated for by changing the volume scattering coefficient. It provides values for reflected and transmitted fluxes and intensities that are accurate to better than 1% for most angles and for widely differing values of the absorption and total optical depth.
TL;DR: In this paper, numerical methods are used to solve the field equations for heat transfer in a porous medium filled with gas and bounded by plane rectangular surfaces at different temperatures, and the relative increases in heat transfer rate, corresponding to natural convection, are obtained as functions of 3-dimensional parameters: the Darcy number Da, the Rayleigh number Ra and a geometric aspect ratio L/D.
Abstract: Numerical methods are used to solve the field equations for heat transfer in a porous medium filled with gas and bounded by plane rectangular surfaces at different temperatures. The results are presented in terms of theoretical streamlines and isotherms. From these the relative increases in heat transfer rate, corresponding to natural convection, are obtained as functions of 3- dimensionless parameters: the Darcy number Da, the Rayleigh number Ra, and a geometric aspect ratio L/D. A possible correlation using the lumped parameter Da Ra is proposed for Da Ra greater than about 40. (33 refs.)
TL;DR: In this article, the authors present flow and heat transfer results obtained by a point successive over-relaxation method for steady fully developed laminar flow in curved rectangular channels under the thermal boundary conditions of axially uniform wall heat flux and peripherally uniform wall temperature.
TL;DR: In this paper, heat transfer data for individual water droplets impinging upon a heat surface were presented, where the droplet diameters ranged from 200 to 400 μm and the approach velocities from 8 to 33 ft/s.
TL;DR: With the advent of crystal settling in a solidifying igneous intrusion, the roof contact of the intrusion may be continuously subjected to temperatures approaching those of the magma itself as mentioned in this paper, which may result in the formation of fire.
Abstract: With the advent of crystal settling in a solidifying igneous intrusion, the roof contact of the intrusion may be continuously subjected to temperatures approaching those of the magma itself. This c...
01 Jun 1970
TL;DR: In this article, measurements of instantaneous heat transfer rates from the working fluid to the cylinder head of a small open-chamber, four-stroke, compressionignition engine have been made at five points on the surface, using a new form of thin-film thermocouple.
Abstract: Measurements of instantaneous heat transfer rates from the working fluid to the cylinder head of a small open-chamber, four-stroke, compression-ignition engine have been made at five points on the surface, using a new form of thin-film thermocouple. These observations demonstrate that flux magnitude and the form of flux variation during the cycle depend greatly on local conditions. Some of the observed phenomena are explained qualitatively. Finally, some results are presented of an analysis of fluxes averaged over all five locations, in terms of the bulk mean properties of the working fluid. It is shown that some compensation for the non-steady nature of the situation may be given by adding to the usual type of quasi-steady relation a term involving the time derivative of the bulk mean temperature.
TL;DR: In this article, the authors presented experimental results for heat transfer by free and forced convection at low velocities from small heated cylinders in dilute solutions of polyethylene oxide in water.
Abstract: Experimental results are presented for heat transfer by free and forced convection at low velocities from small heated cylinders in dilute solutions of polyethylene oxide in water. The experiments were conducted for a range of velocities (less than 1. 0 ft/sec) and polymer concentrations, with several cylinder diameters, and for several polymer molecular weights. Experimental results are also presented for the drag of a small cylinder in similar liquids and for a comparable range of velocities.
The heat transfer and drag results at low velocities were identical to those for a Newtonian liquid; at high velocities, the measured values departed considerably from Newtonian results. These departures result from the viscoelastic nature of the polymer solutions. Visualization studies of the flow around a cylinder and of a minute laminar jet were conducted to determine the gross magnitude of the viscoelastic effects. Due to the liquid's elasticity, a significant enlargement of the flow field was observed for both configurations above a critical Reynolds number. An attempt is made to explain the heat transfer and drag results in light of these observations.
Photographic materials on pp. 111 - 149 are essential and will not reproduce clearly on Xerox copies. Photographic copies should be ordered
TL;DR: In this article, a simultaneous time dependent solution in the height range from 120 to 1500 km is described of the continuity equations for the ions O+, O2+, NO+, H+, of the heat conduction equations for O+ and H+, the electrons, and the neutral gas, and equations of motion for the West-East and North-South neutral wind velocities.
TL;DR: In this article, an experimental investigation is described concerning natural convection between two isothermal concentric spheres of various diameter ratios ranging from 1.09 to 2.81, and a k eff k vs. Rayleigh number heat transfer correlation is presented for each of the three fluids individually, and an overall expression based solely on modified Rayleigh numbers is presented which correlates all three liquids as well as air.
TL;DR: Turbulent and laminar heat transfer to gases in circular ducts entry region, considering various gas properties was studied in this paper, where the authors considered the gas properties.
TL;DR: For any Prandtl number and for arbitrary vertical temperature or heat flux distribution at the cylinder surface, local heat transfer coefficients are represented non-dimensionally by the following approximate formulae as mentioned in this paper.
TL;DR: The use of film cooling for protecting a surface exposed to high temperature air at hypersonic speeds is investigated experimentally in this paper, where the effect of injection on the velocity, temperature and Mach number profiles is studied.
Abstract: The use of film cooling for protecting a surface exposed to high temperature air at hypersonic speeds is investigated experimentally. The tests were conducted in a Mach 6 contoured axisymmetric nozzle with a streamlined centerbody. The Reynolds number in the test section was in the range of 1-3.6 X 10 6/in.; and a wall to freestream temperature ratio of 0.635. Heat-transfer distributions downstream of the slot were obtained for various mass flow rates and the effect of injection on the velocity, temperature and Mach number profiles was studied. Correlations for the cooling lengths with the blowing rate parameters X = pjUj/peUe for the various coolants-—air, helium, hydrogen, and argon were obtained. Correlations for the heattransfer rates in the form (1 — q/go.») an
TL;DR: In this paper, a finite difference solution in the laminar flow field was achieved by modifying the potential flow field to yield convective terms equivalent to the LQE terms in the energy equation.