Showing papers on "Heat transfer coefficient published in 1970"
305 citations
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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: 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.
174 citations
174 citations
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.
137 citations
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.
127 citations
112 citations
105 citations
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.
104 citations
66 citations
TL;DR: In this article, it was shown that the fractional increase in heat transfer coefficient due to the presence of solids was always less than the increase in the friction factor, and further evidence that turbulence is suppressed by the particles, particularly when the duct is small and Re is large.
Abstract: This paper is a sequel to two earlier studies of friction (I)† and eddy diffusion (2) carried out for the same flow conditions as in the present study of heat transfer. Heat was transferred to an upward flowing suspension of 0-40 μ zinc particles in pipes of 1, 2 and 3 in bore. The solids/gas flow rate was in the range 0 < Ws/Wg< 17 and the pipe Reynolds number in the range 3·5 × 104< Re < 105.It was found that the fractional increase in heat transfer coefficient due to the presence of solids was always less than the increase in the friction factor. Minimum values of both these parameters are often observed in the range 1 < Ws/Wq< 2·5. This paper gives further evidence that turbulence is suppressed by the particles, particularly when the duct is small and Re is large; in this case the wall Nusselt number, Nus, is markedly reduced below the value when gas flows alone. However, when the pipe is large and Re is low, Nus can be substantially higher than the value for gas alone. In this case the suspension is ...
TL;DR: In this paper, the effect of mechanical vibrations on convective heat transfer in an enclosure of rectangular cross-section was investigated experimentally and the results showed that vibration of a thermally active enclosure can have a significant effect on its heat transfer characteristics especially near the resonant natural frequency of the column of fluid contained within the enclosure.
Abstract: The effect of mechanical vibrations on natural convective heat transfer in an enclosure of rectangular cross-section was investigated experimentally. The enclosure was comprised of two vertical and opposed surfaces which were maintained at different temperatures, surrounded by four other adiabatic surfaces. Vibration stresses were applied to this heat transfer cell by mounting it vertically on the armature of an electrodynamic vibrator. Frequencies from 0 to 4000 Hertz and accelerations from 0 to 110 g’s were utilized in the investigation. The results show that vibration of a thermally active enclosure can have a significant effect on its heat transfer characteristics especially near the resonant natural frequency of the column of fluid contained within the enclosure. Increases in convective heat transfer coefficients of as much as 50 percent were obtained during this investigation. A correlation equation was developed by utilizing the dynamic response characteristics of the fluid column when considered as a seismic mass.
TL;DR: In this article, the heat and mass transfer coefficients for laminar free convection driven by simultaneous differences in temperature and composition were derived for horizontal cylinders or vertical axisymmetric bodies with arbitrary body contours.
Abstract: Expressions are derived for the heat and mass transfer coefficients for laminar free convection driven by simultaneous differences in temperature and composition for the asymptotic cases of equal Schmidt and Prandtl numbers approaching zero, equal Schmidt and Prandtl numbers approaching infinity, Schmidt number approaching infinity and Prandtl number approaching zero, and Schmidt number larger than Prandtl number and Prandtl number approaching infinity.
The results are applicable for horizontal cylinders or vertical axisymmetric bodies with arbitrary body contours insofar as the approximations of boundary-layer theory are valid. The results compare favorably with existing solutions and experimental results for particular conditions.
TL;DR: In this paper, the effect of fin geometry and temperature on the respective heat transfer coefficients for the upper, vertical, and lower edges of fin arrays has been clarified, and empirical formulas for the respective average Nusselt numbers are obtained.
Abstract: As a sequel to the previous report of this series, the author has this time taken up the fin-edge as one component surface composing a fin array and experimentally studied natural convection heat transfer from the fin-edges in air. The effect of fin geometry and temperature on the respective heat transfer coefficients for the upper, vertical, and lower edges of fin arrays has been clarified. Furthermore, empirical formulas for the respective average Nusselt numbers are obtained. It is found that the heat transfer coefficients for the lower and vertical edges show fairly high values, e.g. 20∼30kcal/m2hr°C.
TL;DR: In this article, the calibration factor of a heat flux meter is expressed as a linear function of the thermal conductivity of the medium encompassing the meter, and the slope of the line depends on the geometry and thermal conductivities of the meter.
TL;DR: In this article, it was shown experimentally that a corona discharge established on a heated wire immersed in a cooler gas enhances heat transfer from the wire to the gas, ostensibly by disrupting the boundary layer about the wire.
01 Jun 1970
TL;DR: The position of the maximum heat transfer coefficient appears to be coincident with the maximum air concentration, or the position the tips of the fuel sprays have reached at the time of ignition, and the radial variation of heat transfer is possibly related to the amount of fuel burnt at each radius as discussed by the authors.
Abstract: Heat transfer coefficients have been measured on the gas side of pistons and liners, the water side of liners, and the oil side of pistons. A significant radial variation in heat transfer across the piston crown has been found. The position of the maximum heat transfer coefficient appears to be coincident with the maximum air concentration, or the position the tips of the fuel sprays have reached at the time of ignition, and the radial variation of heat transfer is possibly related to the amount of fuel burnt at each radius. For four-stroke engines, equations are presented to describe this variation. Heat transfer coefficients at the exposed section of the liner have been found to be similar to the values at the outer edge of the piston.Heat transfer between piston undercrown and cooling oil has been measured for various types of cooling arrangement and, for jet cooling, an expression has been suggested for the heat transfer coefficient.Equations have also been derived to enable coefficients to be predict...
TL;DR: In this article, a series of forced convection boiling and heat transfer experiments has been performed on the sodium boiling loop (NSK) and the results of the preliminary liquid-phase heat transfer measurements at heat fluxes up to 720 W/cm2 can be correlated by the equation Nu = 5.3 + 0.018 ⋅ P e 0.85
TL;DR: In this paper, the problem of determining the heat transfer in fully developed turbulent flow of a non-gray radiating gas in a circular tube was considered and the effects of radiation on the temperature profile and the Nusselt number were reported.
TL;DR: In this article, the authors measured the heat transfer from a horizontal platinum wire to carbon dioxide over a pressure range from 0·8 to 1·1 of the critical pressure, and showed that the temperature transfer coefficient at conditions very close to the critical point is very large.
TL;DR: In this article, the one-dimensional transient heating by solar radiation of a semi-transparent medium and the adjoining fluid is analyzed; the closed-form solution is compared with the values for temperature obtained by finite difference.
TL;DR: In this article, the heat transfer in a conducting, emitting and absorbing medium bounded by two infinite coaxial cylindrical surfaces is analyzed, and the effect of radiation on the heat flow is afforded by the calculation of radiation potential.
TL;DR: In this paper, it was shown that the magnitude of surface-to-bed heat transfer coefficients is dependent on the frequency of particle exchange between the bulk of the bed and the vicinity of the heat transfer surface.