Steady-state heat transfer through a wall with longitudinal rectangular fins and variable thermal conductivity

A method is examined of solving steady-state problems of heat transfer through a surface with longitudinal rectangular fins in the case when the thermal conductivity depends on temperature.Notation T temperature - T₀ temperature of coolant - T₁ temperature at base of fin - T_N some characteristic temperature - (T) thermal conductivity of fin material - heat transfer coefficient; F-cross-sectional area of fin - fin perimeter - h fin height - L fin length - fin thickness - Q heat flux - O_i change of temperature in i-th section - T_i mean temperature at i-th section     

Nonstationary heat transfer in a heterogeneous medium

We consider heat transfer in the displacement of a hot interstitial liquid from an artificially cracked region formed by a camouflet explosion.     

Nonstationary heat transfer in a scattering medium

A numerical solution is given for nonstationary heat transfer in a bed showing thermal conduction, radiation scattering, and chemical heat production. The thermal-exposition situation is considered for a cloud of fine particles. It is found that the optical thickness of the medium affects the induction period.Transated from Inzhenerno-Fizicheskii Zhurnal, Vol. 34, No. 6, pp. 1090–1095, June, 1978.     

Investigation of heat transfer in longitudinal air flow over a staggered tube bundle

Results are presented of an investigation of heat transfer in a longitudinal blow of air over a staggered tube bundle with s/d=1.2 and with heating and cooling in the range Re=2 · 10³–10⁵.     

Hydrodynamics and heat transfer in channels with circular fins

Numerical analysis is performed of the hydrodynamics and heat transfer under conditions of a steady-state fully developed flow of a viscous incompressible liquid in a round pipe with internal circular fins. A numerical model is constructed for the calculation of laminar flows with a constant value of power spent for pumping. The results are given of the investigation of the effect of the height of fins and their number on the hydraulic characteristics and heat transfer in the channel.Translated from Teplofizika Vysokikh Temperatur, Vol. 42, No. 6, 2004, pp. 917–920.Original Russian Text Copyright © 2004 by P. T. Zubkov, and E. N. Tatasova.     

Nonstationary heat and mass transfer with a reduction of the heat load in a heat exchanger with twisted tubes

The results of an investigation of the nonstationary mixing of the heat-transfer agent accompanying the reduction of the heat load in a bundle of twisted tubes are presented, and a generalizing dependence for calculating the effective coefficient of diffusion is derived.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 54, No. 4, pp. 533–539, April, 1988.     

Conjugate heat transfer in solar collector panels with internal longitudinal corrugated fins—Part I: Overall results

A computational study is conducted to examine the fully developed laminar flow and heat transfer characteristics in solar collector panels with internal, longitudinal, corrugated fins. The fins are integrally attached to the upper and lower panel walls. The objective of the study is to determine the effects of varying the fin pitch (or fin angle), the fin thickness, the ratio of the thermal conductivity of the panel walls and the fin to that of the fluid, and the thermal boundary condition on the panel heat transfer and pressure drop. The solutions of the momentum and energy equations are obtained by using a control-volume-based finite difference algorithm. The results of the study are also applicable to the design of internally-finned channels in compact heat exchangers. The overall panel heat transfer increases when the fin pitch (or the fin angle) is decreased, when the fin thickness is increased, and when the thermal conductivity ratio is increased. The streamwise pressure drop increases with decreasing fin pitch (or fin angle) and increasing fin thickness. For a fixed fin thickness, the selection of a small fin pitch (or fin angle) over the range studied results in a higher heat transfer enhancement per unit pumping power.     

Nonstationary problem of heat transfer in laminar-vacuum insulation

A mathematical model for nonstationary heat and mass transfer in multilayered insulation for the case of transverse evacuation of the packet is proposed. Results of numerical computations of the gas pressure, the shield temperature, and the heat flux in the packet for certain insulation variants are presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 32, No. 5, pp. 806–813, May, 1977.     

Local heat exchange of a single transversely bathed round tube with external circular fins

Under conditions of transverse bathing of a finned tube by air the distributions of local heat-transfer coefficients on the lateral faces and ends of a circular fin and on the fin-free surface of the tube proper are determined using heat-flux pickups.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 30, No. 2, pp. 274–280, February, 1976.     

Nonstationary heat transfer to the walls of a cylindrical channel filled with liquid

The results of an experimental investigation into the nonstationary (transient) heat transfer from an external medium to the walls of a dead-end cylindrical channel filled with liquid and closed by a copper bottom are presented. The experimental apparatus and method of conducting the experiments are described.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No, 6, pp. 1005–1009, December, 1969.     

Nonstationary heat transfer in a channel containing saturated He II: stepped heat loading

Measurements have been made on the nonstationary temperature distribution in a channel containing saturated superfluid helium with local stepped heat input. A numerical method has been developed, which incorporates the variable thermophysical parameters for the helium.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 54, No. 3, pp. 361–367, March, 1988.     

Investigation of the intensification of heat transfer in a dense tube bundle washed by a longitudinal air flow

Experiments have been performed to investigate the intensification of heating and cooling obtained by periodically grooving the tubes of a staggered bundle with S/D=1.2 washed by a longitudinal air flow in the range Re=2 · 10³–10⁵. Tubular heat exchangers with longitudinal flow through the intertube space are widely used in a number of branches of technology. To develop more compact exchangers it is necessary not only to intensify heat transfer in the intertube space by creating turbulence in various ways but also to use dense bundles of tubes (relative pitch S/D 1.2).     

Local heat transfer between a moving sand heap and annular fins

It is shown here how the heat transfer intensity distributes over the surface of annular fins cooled by a transversely moving heap of dense loose material. The heat conduction through the fins is analyzed and the fin efficiency is corrected to account for the radial nonuniformity of the heat transfer distribution.Translated from Inzhenerno-Fizicheskil Zhurnal, Vol. 20, No. 6, pp. 1066–1071, June, 1971.     

Hydraulic resistance and heat transfer in longitudinal flow past staggered tube bundles with walls of divergent-convergent profile

The results of an experimental investigation into the effect of the characteristic dimensions of staggered convergent-divergent bue bundles on hydraulic resistance and heat transfer in a longitudinal flow are presented.Bryansk Institute of of Transport Machine Building. Translated from Inzhenerno-Fizicheskii Zhrunal, Vol. 62, No. 6, pp. 803–807, June, 1992.     

Nonstationary heat transfer in anisotropic half-space under the conditions of heat exchange with the environment having a specified temperature

An analytical solution to the problem of heating anisotropic half-space by the environment with a spatially and temporally variable temperature (boundary conditions of the third kind at an anisotropic body) has been obtained for the first time based on the construction of the boundary influence function (the Green’s function), which is determined using the Fourier and Laplace integral transforms. Nonstationary temperature fields in anisotropic blunt bodies have been found under the conditions of aero-gas-dynamic heating of hypersonic aircrafts with different heat-transfer coefficients and incoming-flow temperatures. The solution obtained is recommended for determining the state of thermal protection fabricated from composites which are generally anisotropic.     

Nonstationary heat transfer in an inhomogeneous thermally insulated timber sample

A mathematical model and numerical methods to calculate the thermal state of a fragment of the exterior timber wall of a building are suggested. The character of the distribution of temperature fields in homogeneous and inhomogeneous (thermally insulated) timbers and the influence of the thermophysical and geometrical characteristics of a homogeneous timber sample and warmth-keeping lagging on it are determined. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 3, pp. 20–25, May–June, 2006.     

Film condensation heat transfer of helium in a vertical tube

Helium was condensed on the wall of a vertical copper tube (14 mm in diameter, 32 mm long) in the experimental range: vapour temperature in the tube ? 4.1–5.0 K; heat flux ? 0.5–86 mW cm^?2; temperature differences across a liquid film ? 0.01–1.3 K ;film Reynolds numbers ? 3–380.It was found that the heat flux increased linearly with the film temperature difference, yielding a constant heat transfer coefficient of about 0.065 W cm^?2 K^?1. The discrepancy between the experimental results and the laminar condensation theory is also considered.     

Nonstationary spatial heat transfer in the inhomogeneous corner fragment of a wooden bar wall

A study has been made of the state of the external corner of a wooden bar wall of a building. The character of distribution of the temperature and heat fluxes in the inhomogeneous corner fragment has been established, and the influence of the anisotropy on the temperature distribution on its interior and exterior surfaces has been evaluated. The additional heat loss through the interior heat-absorbing surface of the corner fragment in relation to the heat loss through the smooth surface of the wall has been determined.