Showing papers on "Heat transfer coefficient published in 1968"
TL;DR: The Thermophysical Properties Research Literature Retrieval Guide as discussed by the authors was published by Y. S. Touloukian, J. K. Gerritsen and N. Y. Moore.
Abstract: Thermophysical Properties Research Literature Retrieval Guide Edited by Y. S. Touloukian, J. K. Gerritsen and N. Y. Moore Second edition, revised and expanded. Book 1: Pp. xxi + 819. Book 2: Pp.621. Book 3: Pp. ix + 1315. (New York: Plenum Press, 1967.) n.p.
1,240 citations
TL;DR: A = E(l T^ admittance function, Eq. (1) sensitivity of gas phase to pressure changes specific heats of solid and gas activation energy for surface reaction E = ES/RTS enthalpy latent heat for surface reactions; Hp > 0 for exothermic s_urface reaction H = Hp/cT average mass flux fluctuation of mass flux at the surface index in the linear burning rate law, r = ap index in surface pyrolysis law as discussed by the authors.
Abstract: A = E(l T^ admittance function, Eq. (1) sensitivity of gas phase to pressure changes specific heats of solid and gas activation energy for surface reaction E = ES/RTS enthalpy latent heat for surface reaction; Hp > 0 for exothermic s_urface reaction H = Hp/cT average mass flux fluctuation of mass flux at the surface index in the linear burning rate law, r = ap index in the surface pyrolysis law, Eq. (25) average heat release (per unit volume) in solid heat release in gas phase fluctuations of heat transfer at the average position of the surface, x = 0 fluctuations of heat release at the burning surface linear burning rate universal gas constant initial temperature of propellant, x -*• — co temperature of burning surface flame temperature average chamber temperature, x -*+ °° surface displacement, velocity functions defined in Eqs. (22) and (27) functions defined in Eqs. (22) and (27) stands for p'/p Eqs. (17-20) thermal conductivities of solid and gas stands for (ms'/m)r density of solid propellant and gas phase average density in chamber normalized temperature or a time lag dimensionless frequency parameters for the solid and gas phases; Eqs. (18) and following Eq. (34) real angular frequency mean value fluctuating value evaluated at the solid-gas interface evaluated on the gas (+) or solid ( — ) side evaluated on the gas or solid side of the mean position of the burning surface evaluated at the flame, or just downstream of the flame real part imaginary part
216 citations
TL;DR: Friction, momentum and gravity interactions effect on heat transfer process during annular flow condensation during heat transfer was studied in this paper, where friction, momentum, and gravity interaction effects were considered.
Abstract: Friction, momentum and gravity interactions effect on heat transfer process during annular flow condensation
211 citations
TL;DR: In this article, the authors used a modified thermo-balance to measure the diffusion coefficient and thermal conductivity of the porous lime layer, and the mass and heat transfer coefficients to the surface of the compact.
149 citations
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TL;DR: The VAPOR HEAT PIPE as mentioned in this paper is a closed, EVACUATED CHAMBER, whose interior wall is filled with a volatile fluid, which is used for transferring heat energy from one end of the pipe to the other.
Abstract: THE HEAT PIPE IS ESSENTIALLY A CLOSED, EVACUATED CHAMBER WHOSE INSIDE WALLS ARE LINED WITH A CAPILLARY STRUCTURE, OR WICK, THAT IS SATURATED WITH A VOLATILE FLUID. THE OPERATION OF THE HEAT PIPE COMBINES VAPOR HEAT TRANSFER AND CAPILLARY ACTION. VAPOR HEAT TRANSFER IS RESPONSIBLE FOR TRANSPORTING THE HEAT ENERGY FROM THE EVAPORATOR SECTION AT ONE END OF THE PIPE TO THE CONDENSER SECTION AT THE OTHER END. CAPILLARY ACTION IS RESPONSIBLE FOR RETURNING THE CONDENSED WORKING FLUID BACK TO THE EVAPORATOR SECTION. THE VAPORIZED FLUID STORES HEAT ENERGY AT THE TEMPERATURE AT WHICH THE VAPOR WAS CREATED AND WILL RETAIN THE ENERGY AT THAT TEMPERATURE UNTIL IT MEETS A COLDER SURFACE. THIS TENDENCY TO RESIST ANY DIFFERENCE IN TEMPERATURE WITHIN THE HEAT PIPE IS RESPONSIBLE FOR THE DEVICE'S HIGH THERMAL CONDUCTANCE. THE HEAT PIPE CAN OPERATE AGAINST GRAVITY AND WITHOUT A SECOND EXTERNAL ENERGY SOURCE. DEVICES THAT OPERATE ON THE PRINCIPLE OF VAPOR HEAT TRANSFER CAN HAVE SEVERAL THOUSAND TIMES THE HEAT-TRANSFER CAPACITY OF THE BEST METALLIC CONDUCTORS. HEAT PIPES HAVE BEEN MADE TO OPERATE AT VARIOUS TEMPERATURES SPANNING THE RANGE FROM BELOW FREEZING TO OVER 3,600 F. THE POWER TRANSFERRED RANGES FROM A FEW WATTS TO MORE THAN 17,000 WATTS. THE HEAT PIPE IS A UNIQUE AND VERSATILE HEAT-TRANSFER DEVICE. ITS SPECIAL PROPERTIES ARE HIGH THERMAL CONDUCTANCE, TEMPERATURE FLATTENING, HEAT-FLUX TRANSFORMATION AND SEPARATION OF HEAT SOURCE FROM HEAT SINK.
142 citations
TL;DR: In this paper, the authors investigated the relationship between the skin friction part of the drag on a natural surface and a simultaneous transfer of mass or heat, and measured the dimensionless transfer coefficients Cd, Cv and Ch for the exchange of (streamwise) momentum, mass, and heat, between a single artificial leaf and the airflow in a wind-tunnel.
Abstract: Investigation of a proposed relationship between the skin friction part of the drag on a natural surface and a simultaneous transfer of mass or (sensible) heat led to measurements of the dimensionless transfer coefficients Cd, Cv and Ch for the exchange of (stream-wise) momentum, mass, and heat, between a single artificial leaf and the airflow in a wind-tunnel. It was shown that Cv, h = C0(D/v, k/v)2/3 where D, k and v are the molecular diffusivities in air of gas or vapour, heat, and momentum, and where C0 is a generalized mass or heat transfer coefficient almost independent of ϕ, the angle of incidence between the leaf and the airflow, Cd, however, made up of a bluff-body or pressure part Cb, in addition to a molecular skin friction part Cf, depended strongly on ϕ. C0 was close to the theoretical skin friction drag coefficient at ϕ = 0 of a thin flat plate with dimensions similar to the leaf. As a general relation between the corresponding coefficients of a natural rough surface CF = βC0, where β lies between 0·1 and unity, depending on the form and inclination (ϕ) of the roughness elements, and on wind speed.
C0 was shown experimentally to be proportional to (wind speed)−1/2 in a regime of fully-forced convection. When the evaporation from one side of the leaf was stopped, the transfer coefficient for the removal of vapour from the other side increased by about 30 per cent. An accurate form of the psychrometric constant of the leaf includes the factor (k/D)2/3, which has the value 0·90 for water vapour.
142 citations
90 citations
TL;DR: In this article, a dimensionless criterion is proposed to measure the ratio of energy of mean flow and that dispersed near the wall in the transition from laminar to turbulent, which can be applied for a wider range of Grashof and Prandtl numbers.
81 citations
01 Sep 1968
TL;DR: In this paper, the heat transfer in the region of circular pipes close to the beginning of the heating section is investigated for low-Peclet-number flows with fully developed laminar velocity profile.
Abstract: The heat transfer in the region of circular pipes close to the beginning of the heating section is investigated for low-Peclet-number flows with fully developed laminar velocity profile. Axial heat conduction is included and its effect on the temperature distribution is studied not only for the region downstream of the start of heating but also for that upstream. The energy equation is solved numerically by a finite difference method. Results are presented graphically for various Peclet numbers between 1 and 50. The boundary conditions are uniform wall temperature and uniform wall heat flux with step change at a certain cross-section. For the latter case, also some results for the region near the end of the heating section are reported. The solutions are applicable for the corresponding mass transfer situations where axial diffusion is important if the temperature is replaced by the concentration andPe byReSc.
76 citations
TL;DR: Stagnation point convective heat transfer in frozen boundary layers to surfaces having widely differing catalytic activity in ionized flows is studied in this paper, where the authors show that it is possible to transfer heat from a frozen boundary layer to surfaces with different catalytic activities.
Abstract: Stagnation point convective heat transfer in frozen boundary layers to surfaces having widely differing catalytic activity in ionized flows
70 citations
TL;DR: In this article, the effect of electric fields on boiling heat transfer has been investigated and it is shown that the major effects occur in the regions of peak heat flux, transition boiling, and minimum transition boiling.
Abstract: The results of previous experiments to determine the effect of an electric field on boiling heat transfer are reviewed. It is pointed out that the major effects occur in the regions of peak heat flux, transition boiling, and minimum transition boiling. These boiling regions are known to be heavily influenced by hydrodynamic stability. Hydrodynamic stability is influenced by the presence of an electric field. The hydrodynamic theory of boiling heat transfer is therefore reconstructed, including the effects of a perpendicular electric field across the interface separating vapor and liquid phases. The result is the ratio of the boiling heattransfer rate in the presence of an electric field to that with zero field, as a function of the electric-field strength and the physical parameters of the boiling medium. The calculations are restricted to nonconducting fluids, that is, good dielectrics. The analytical results are compared with recent, but somewhat restricted experimental results and, within the inherent complexities of the problem, the agreement is good. Apparently the theory predicts the correct functional form of the data.
TL;DR: In this paper, the effect of secondary fluid injection through single nontangential slots on surface heat transfer in regions near the injection site was studied, and experimental results were obtained which cover the range of interest of these parameters for many situations encountered in film cooling applications.
Abstract: A study of the effect of secondary fluid injection through single nontangential slots on the surface heat transfer in regions near the injection site is presented. The nondimensional parameters governing the heat transfer are obtained from the pertinent differential equations, and experimental results were obtained which cover the range of interest of these parameters for many situations encountered in film cooling applications. The experimental heat transfer rates were obtained from a novel transient test facility, and are presented as ratios of the heat transfer obtained with film injection to the heat transfer obtained with only the single mainstream.
TL;DR: In this article, an expansion for the Nusselt number is given up to and including the term of order R 2 for the case R < 1, where the Prandtl number is of order unity.
Abstract: The present paper deals with the temperature field past an isothermal sphere. Acrivos & Taylor (1962) have obtained results for the case R [les ] 1 with no restriction on the Prandtl number. The results of the present paper are for the case R < 1 in which the Prandtl number is of order unity. An expansion for the Nusselt number is given up to and including the term of order R2.
01 Jan 1968
TL;DR: In this article, a single correlating equation for single phase forced convection heat transfer coefficients for turbulent flow through tubes over wide ranges of temperature ratios was proposed, where the convection transfer coefficients were derived from a single phase forcing convection.
Abstract: Single correlating equation for single phase forced convection heat transfer coefficients for turbulent flow through tubes over wide ranges of temperature ratios
TL;DR: In this paper, the specific heat of high purity aluminum has been measured from 330 to 890°K with an estimated accuracy of ± 0.7 per cent, using dynamic adiabatic calorimetry.
TL;DR: In this paper, the spectral radiant heat flux distribution in an absorbing and emitting gas of prescribed temperature distribution contained in a long cylinder whose internal surface is black is derived in terms of integral functions peculiar to the cylindrical geometry.
Abstract: Equations are presented for the spectral radiant heat flux distribution in an absorbing and emitting gas of prescribed temperature distribution contained in a long cylinder whose internal surface is black. The temperature of the gas is taken to vary in the radial direction only, while the absorption coefficient of the gas is taken to vary with temperature as well as frequency of radiation. Equations are also presented for the radiant heat flux distribution in a gray gas in which the absorption coefficient is a function of temperature only. The equations, which are derived from the general equation of radiative transfer, are presented in terms of integral functions peculiar to the cylindrical geometry. Radiant heat flux distributions are calculated for several absorption coefficient and temperature distributions with the gray-gas model. The effects of absorption coefficient and temperature profiles on the heat flux distribution in a cylindrical medium are compared with equivalent effects in a plane parallel medium. The effects of absorption coefficient and temperature profiles on the heat flux distribution in the annular region between two concentric cylinders are also examined for cases in which the inner cylinder is a core of very opaque gas.
TL;DR: Theoretical results for forced heat convection from a circular cylinder at low Reynolds numbers are given in this paper, where the analysis in each case is based upon the matched asymptotic expansions.
Abstract: Theoretical results are obtained for forced heat convection from a circular cylinder at low Reynolds numbers. Consideration is given to the cases of a moderate and a large Prandtl number, the analysis in each case being based upon the method of matched asymptotic expansions. Comparison between the moderate Prandtl number theory and known experimental results indicates excellent agreement; no relevant experimental work has been found for comparison with the large Prandtl number theory.
TL;DR: In this article, the authors investigated the thermal interaction between the atmosphere and the underlying earth, as related to the diurnal heat wave, through the use of a modified virtual conduction model in which the influences of turbulence and thermal convection are simulated by diffusion while the influence of terrestrial radiation is approximated partly by diffusion and partly by a Newtonian cooling, the ratio between the two parts increasing from summer to winter.
Abstract: The thermal interaction between the atmosphere and the underlying earth, as related to the diurnal heat wave, is investigated through the use of a modified virtual conduction model in which the influences of turbulence and thermal convection are simulated by diffusion while the influence of terrestrial radiation is approximated partly by diffusion and partly by a Newtonian cooling, the ratio between the two parts increasing from summer to winter. The virtual thermal diffusivity is assumed to vary both in time and in space in order to represent the various physical processes involved in accomplishing the actual heat transfer. It is shown that a mean upward transport of heat is maintained through the diurnal variation of the transfer process although the mean lapse rate is stable, thereby removing a long-standing difficulty in evalutating the turbulent heat flux from the mean potential temperature distribution. The solar energy received at the surface is found to be partitioned into the two media a...
TL;DR: In this article, a semi-empirical analogy between heat and momentum transfer was used to estimate heat transfer rates for flows of dilute polymer solutions which exhibit drag reduction, which is limited to the range of Prandtl numbers larger than one and smaller than fifty.
TL;DR: In this paper, the authors investigated the thermal response of an incompressible, laminar boundary layer over a semi-infinite flat plate due to a step change in either the wall temperature or wall flux.
TL;DR: In this paper, the heat capacity of a single-phase sample of α-Ce has been measured and the magnitude of the electronic heat capacity has been determined unambiguously since there is no magnetic heat capacity, indicating a substantial 4f contribution to the density of states.
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TL;DR: In this paper, an experimental investigation has been made of a flame impinging at an angle of 20° on the hearth of a furnace, and measured velocity and temperature profiles in the flame were found to have the same reduced form as profiles obtained for a plane heated impinging jet, by Mathieu.
TL;DR: In this paper, the authors reported the results of experiments conducted in the 20in. supersonic wind tunnel at the Jet Propulsion Laboratory of the California Institute of Technology on the effect of heat transfer (cooling) on the size of single spherical roughness elements required to produce a minimum transition Reynolds number on a 43in. 10° cone.
Abstract: The paper reports the results of experiments conducted in the 20in. supersonic wind tunnel at the Jet Propulsion Laboratory of the California Institute of Technology on the effect of heat transfer (cooling) on the size of single spherical roughness elements required to produce a minimum transition Reynolds number on a 43-in. 10° cone. The results are an extension of previous work on an adiabatic cone and show a linear effect of wall temperature reduction on size of roughness. The dependence of roughness size on trip position, Mach number, and surface temperature is expressed in a simple relation.