scholarly journals Evaluation model of the steady-state heat transfer performance of two-phase closed thermosyphons

2021 ◽  
pp. 166-166
Author(s):  
Yafeng Wu ◽  
Zhe Zhang ◽  
Wenbin Li ◽  
Daochun Xu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Steady State ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Two Phase ◽  
Equivalent Thermal Conductivity ◽  
State Heat ◽  
Steady State Heat ◽  
Steady State Heat Transfer

Two-phase closed thermosyphons have good thermal conductivity and are widely used in heat transfer applications. It is essential to establish an effective method for evaluating the steady-state heat transfer performance of two-phase closed thermosyphons, as such a method can help to select appropriate designs and to improve the efficiency of these devices. In this paper, the equivalent thermal conductivity is derived by the principle of equal total thermal resistance, in which the influence of the adiabatic length is eliminated. An evaluation model of the steady-state heat transfer performance of two-phase closed thermosyphons is established. Test results of three two-phase closed thermosyphons with total lengths of 220 mm, 320 mm and 500 mm show that as the heat transfer rate increases, the equivalent thermal conductivity of these devices decreases by 28.91%, increases by 6.10% and increases by 10.02%, respectively, among which the minimum value is 831.63 W?m-1?K-1and the maximum value is 1694.19 W?m-1?K-1. The decrease (increase) in the equivalent thermal conductivity in the evaluation model indicates a decrease (increase) in the heat transfer performance. The results show that the equivalent thermal conductivity of the model can effectively evaluate the heat transfer performance of two-phase closed thermosyphons.

Microflow Heat Transfer Effectiveness: Questioning the “Area/Volume-Argument”

2011 ◽  
Author(s):  
Heinz Herwig
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Steady State ◽  
Thermal Boundary Layer ◽  
Heat Transfer Performance ◽  
Characteristic Length ◽  
Transfer Performance ◽  
Layer Behavior ◽  
Steady State Heat ◽  
Steady State Heat Transfer

The often used argument that heat transfer in micro-sized devices is superior due to the fact that the transfer area scales like L2 but the volume like L3 with L as a characteristic length is critically analyzed for various heat transfer situations. It turns out that for steady state heat transfer cases the thermal boundary layer behavior is more important. In general, dimensional analysis should be applied to understand how the heat transfer performance changes when scales are reduced from macro- to micro-size.

scholarly journals STEADY-STATE HEAT TRANSFER IN A PLATE WITH TEMPERATURE-DEPENDENT THERMAL CONDUCTIVITY (AN EXACT SOLUTION)

2019 ◽  
Vol 18 (2) ◽  
pp. 85
Author(s):  
A. Miguelis ◽  
R. Pazetto ◽  
R. M. S. Gama
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Steady State ◽  
Transfer Problem ◽  
Internal Heat ◽  
Temperature Dependent ◽  
State Heat ◽  
Kirchhoff Transformation ◽  
Steady State Heat ◽  
Steady State Heat Transfer

This work presents the solution of the steady-state heat transfer problem in a rectangular plate with an internal heat source in a context in which the thermal conductivity depends on the local temperature. This generalization of one of the most classical heat transfer problems is carried out with the aid of the Kirchhoff transformation and employs only well known tools, as the superposition of solutions and the Fourier series. The obtained results illustrate how the usual procedures may be extended for solving more realistic physical problems (since the thermal conductivity of any material is temperature-dependent). A general formula for evaluating the Kirchhoff transformation as well as its inverse is presented too. This work has a strong didactical contribution since such analytical solutions are not found in any classical heat transfer book. In addition, the main idea can be used in a lot of similar problems.

Steady-State Conduction With Variable Thermal Conductivity

1962 ◽  
Vol 84 (1) ◽  
pp. 92-93 ◽  
Author(s):  
Robert K. McMordie
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Steady State ◽  
Variable Thermal Conductivity ◽  
Two Dimensional ◽  
The Real ◽  
State Heat ◽  
Steady State Heat ◽  
Steady State Heat Transfer ◽  
Transfer Problems

A method is developed for solving two-dimensional, steady-state heat-transfer problems with thermal conductivity dependent on temperature. The quantity ∫ KdT is employed in the analysis and although this quantity has been known for some time,2, 3 it seems that the real usefulness of this quantity in analysis has not been, in general, recognized.

Nonuniqueness in Steady-State Heat Transfer in Prestressed Duplex Tubes—Analysis and Case History

1985 ◽  
Vol 52 (2) ◽  
pp. 257-262 ◽  
Author(s):  
M. G. Srinivasan ◽  
D. M. France
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Heat Transfer Performance ◽  
Steady State Solution ◽  
State Solution ◽  
Multiple Steady State ◽  
State Heat ◽  
Steady State Heat ◽  
Steady State Heat Transfer ◽  
Generating System

More than one steady-state solution is shown to exist for the problem of steady-state heat transfer across the walls of a duplex tube when the initial prestress between the inner and outer tubes is sufficiently low. This determination was used in explaining the apparently erratic heat-transfer performance of prestressed duplex tubes in the steam generating system of the Experimental Breeder Reactor II. The importance of the results lies not only in showing that nonuniqueness of steady-state solution applies to more complex geometries than heretofore analyzed, but also in demonstrating that such multiple steady-state conditions appear in practical situations.

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