Showing papers on "Heat transfer coefficient published in 1972"
TL;DR: In this article, a comprehensive set of data was obtained for pressures from 226 to 294 bar, bulk temperatures from 230 to 540°C, heat fluxes from 116 to 930 kW/m 2 and mass velocities from 310 to 1830 kg/m2s.
570 citations
TL;DR: In this paper, the heat transfer between a fluid flowing through a packed bed and the wall is interpreted according to a one-dimensional model characterized by an overall heat transfer coefficient, hw and by two-dimensional models with one parameter, the effective thermal conductivity, ke or two parameters, the Effective Thermal Conductivity (ETC) λe and αw.
360 citations
TL;DR: In this article, the Nusselt number was used for the analysis of turbulent heat and mass transfer in pipes, channels, and boundary layers, where the dimensionless coefficients of the universal logarithmic equations for the velocity and temperature profiles were derived.
279 citations
TL;DR: In this paper, the turbulent Graetz problem is solved numerically for the lower eigenvalues and constants for Reynolds numbers in the range 10 4 Re 6 and for Prandtl numbers in range 0 Pr 4.
216 citations
TL;DR: In this article, a point successive-overrelaxation method was used to solve the thermal energy equation in curved tubes of circular cross section, where the curvature ratio was considered as an additional parameter.
180 citations
TL;DR: In this paper, an experimental investigation was made of the turbulent vapor cavity formed by a steam jet discharging into a subcooled liquid water both considering both constant area and convergent-divergent steam injectors of various external geometries.
Abstract: An experimental investigation was made of the lenght of the turbulent vapor cavity formed by a steam jet discharging into a subcooled liquid water both. The experiments considered both constant area and convergent-divergent steam injectors of various external geometries. The tests were conducted with the bath at atmospheric pressure, bath temperatures in the range 301–358K, injector exit diameters in the range 0.00040–0.0112 m, for choked injector flows having mass velocities in the range 332–2050 kg/m2.s. These conditions yielded injector exit Reynolds numbers from 2 to 150 × 104. Over this range a correlation was developed to yield the length of the vapor cavity as a function of the injector diameter, exit mass velocity, and a driving potential for the condensation process. The heat transfer coefficients for this condensation process were found to be significantly greater than those encountered in turbulent film condensation processes in the vicinity of tubes and walls.
173 citations
TL;DR: In this paper, the authors proposed a non-linear coupled hyperbolic simultaneous partial differential equations (SDPE) model for regenerative heat and mass exchanger, where heat and one or more adsorbates are transferred cyclically from one fluid stream to a porous matrix and then from the porous matrix to the other fluid streams.
170 citations
145 citations
Journal Article•
TL;DR: In this paper, two identical units of heat flow meter panels were used for the experiment and were mounted side by side on the exterior surface of the building and were maintained at slightly different temperatures and the heat flux conducted toward the surface from inside was measured.
Abstract: Two identical units of heat flow meter panels were used for the experiment and were mounted side by side on the exterior surface of the building. They were maintained at slightly different temperatures and the heat flux conducted toward the surface from inside was measured. The two panels received exactly the same incident radiation so the difference in the measured heat conduction was equal to the difference in heat loss by convection and long wave emission. The convective heat transfer coefficient was calculated from the temperature of the two surfaces and the emissivity.
122 citations
TL;DR: In this article, a numerical simulation of dropwise condensation heat transfer was performed with an active site density as high as 109 sites/cm2, and heat transfer to the drop was determined by considering the effects of curvature of the drop surface, interfacial mass transfer between liquid and vapor phases, and conduction through the drop.
114 citations
TL;DR: In this article, two-phase boundary layer equations of filmwise condensation on a horizontal cylinder are solved with an approximate method due to Jacobs, and numerical results for average coefficients of heat transfer are expressed as; Nu=χ 1+ 0·276 χ 4 FrH 1 4 Re 1 2 especially for large vapour velocity, namely for gD U ∞ 2 H ⪡ χ4 0·275 Nu =χ Re 12 where χ=0·9 1+ 1 RH 1 3
TL;DR: In this paper, boundary layer heat transfer coefficients were measured under natural wind conditions using a transient and two steady-state methods using metal disks of diameters from 1.9 to 12.7 cm above several agricultural and nonagricultural surfaces.
TL;DR: In this article, a summarization of five years work on heat transfer to the transpired turbulent boundary layer with transpiration is presented, experimental data are presented and discussed, and theoretical models for solution of the momentum equation under these conditions are presented.
TL;DR: In this article, the authors studied strong nonlinear heat transport across a porous layer using Howard's (1963) variational method and provided the theoretical bounding heat-transport curve, which is consistent with the result of the well-known dimensional argument leading to the one-third power law for regular convection.
Abstract: Strongly nonlinear heat transport across a porous layer is studied using Howard's (1963) variational method. The analysis explores a bifurcation property of Busse's (1969) multi-a solution of this variational problem and complements the 1972 study of Busse & Joseph by further restricting the fields which are allowed to compete for the maximum heat transported a t a given temperature difference. The restriction arises, as in the case of infinite Prandtl number convection studied by Chan (1971), from letting a parameter tend to infinity from the outset; here, however, the parameter which is assumed infinitely large (the Prandtl-Darcy number) is actually seldom smaller than O(107).The theoretical bounding heat-transport curve is computed numerically. The maximizing Nusselt number (Nu) curve is given a t first by a functional of the single-a solution; then this solution bifurcates and the Nusselt number functional is maximized for an interval of Rayleigh numbers (R) by the two-a solution. The agreement between the numerical analysis and recent experiments is striking. The theoretical heat-transport curve is found to be continuously differentiable but has piecewise discontinuous second derivatives.The results of an asymptotic (R → ∞) analysis following Chan (1971) are in qualitative agreement with the results of numerical analysis and give the asymptotic law Nu = 0.016R. This law is consistent with the result of the porous version of the well-known dimensional argument leading to the one-third power law for regular convection. The asymptotic results, however, do not appear to be in good quantitabive agreement with the numerical results.
TL;DR: In this article, the authors deal with natural convection heat transfer from a non-isothermal vertical flat plate immersed in a temperature stratified environment and show that approximations based on the local temperature difference can introduce large errors into the prediction of surface heat transfer rates.
TL;DR: In this article, the authors investigated the flow and heat transfer around two cylinders in cross flow (one of them in the wake of the other) and determined the distribution of the static pressure coefficients and Nusselt number on the surfaces of both cylinders by measurements.
TL;DR: In this article, the maximum achievable rates of heat transfer between a wall surface and a fluidized bed have been further studied in order to control the particle residence times more precisely than is possible in a fluidised bed.
TL;DR: In this paper, an experimental investigation of free convection heat transfer from heated spheres to water is reported, and the experimental data extend over a wide range of Rayleigh number, thus covering the laminar, transition, and beginning of the turbulent regimes.
TL;DR: In this article, a turbulent boundary layer on a porous plate is described, and the transfer of heat mass at the surface of the boundary layer is investigated. But the authors do not consider the transfer in the turbulent boundary layers.
TL;DR: In this article, simple expressions for heat transfer coefficients of steam side and pressure drops through tube banks are proposed, and resistance coefficients are represented graphically, and a comparison is made between the results for the two tube banks of in-line and staggered arrangement with 22/14 spacing-to-diameter ratio.
01 Jun 1972
TL;DR: In this article, structural properties of the Al-Cu alloys were studied as a function of the following solidification conditions at the substrate chill: a) heat sink capacity; b) surface microprofile; c) nature of the liquid metal fluid flow as it makes substrate contact.
Abstract: Structures and substructures in the chill zone have been studied in Al-Cu alloys as a function of the following solidification conditions at the substrate chill: a) heat sink capacity; b) surface microprofile; c) nature of the liquid metal fluid flow as it makes substrate contact. The parameters taken in account both experimentally and analytically are: heat transfer coefficient of the metal/mold interface, surface rugosity of the mold walls, and the Reynolds number of the liquid metal fluid flow. The results obtained show definite correlations between the structural characteristics of the chill zone and the values of the studied parameters.
TL;DR: In this article, the effect of component size on convective heat transfer from small devices (with surface areas between 2·00 and 0·01 sq cm) was investigated analytically and experimentally.
TL;DR: In this paper, the forced-convection mass transfer of various realistic leaf models at Reynolds numbers 2 x 103
Abstract: The forced-convection mass transfer - and by analogy, heat transfer - of various realistic leaf models at Reynolds numbers 2 x 103
TL;DR: In this article, it was shown that the experimentally found values for the heat resistance of a 4He-solid interface in the millidegree range can be explained by taking into account the phonon absorption in the solid as caused e.g. by scattering on surface dislocations.
TL;DR: In this paper, a general formulation valid for all Prandtl numbers is presented and the limiting case of large PrandTL number is approached by a numerical method, where the typical developments of temperature profile, wall temperature and secondary flow in the thermal entrance region are presented for the case of square channel γ = 1.
TL;DR: In this paper, a physical model for the rewetting of a hot dry patch is proposed, where the mechanisms governing the rate of resorption of the dry area are the conduction of heat from the dry to the wet area and the removal of this heat by a large local heat-transfer coefficient.
TL;DR: In this paper, the thermal conductivities of argon, krypton, and nitrogen were measured at 760 mm Hg in the temperature range 800-2000°K and two thermal conductivity columns of different outside diameters were used in the experiments to provide an assessment of the convective heat transfer.
Abstract: The thermal conductivities of argon, krypton, and nitrogen were measured at 760 mm Hg in the temperature range 800–2000°K. Two thermal conductivity columns of different outside diameters were used in the experiments to provide an assessment of the convective heat transfer. In addition, potential leads were employed to minimize convection and end effects. The thermal conductivity values obtained were compared with existing data, with results of viscosity measurements, and with theoretical predictions.
TL;DR: In this paper, the behavior of a tracer particle in a transparent bed in which glass particles have been fluidized by a liquid of the same refractive index has been studied experimentally.