scholarly journals Constructal Equivalent Thermal Resistance Minimization for Tau-Shaped Fin

Entropy ◽  
2020 ◽  
Vol 22 (11) ◽  
pp. 1206
Author(s):  
Shuhuan Wei ◽  
Huijun Feng ◽  
Lingen Chen ◽  
Yanlin Ge
Keyword(s):  
Thermal Resistance ◽  
Heat Transfer Performance ◽  
Constructal Theory ◽  
Width Ratio ◽  
Entransy Dissipation ◽  
Optimal Length ◽  
Entransy Theory ◽  
Engineering Designs ◽  
Material Volume ◽  
Maximum Thermal Resistance

With the aid of constructal theory and entransy theory, a Tau-shaped fin (TAUSF) is investigated in this paper, and the widths of the bend end and elemental fins are assumed to be different. The construct of the TAUSF is optimized by the minimum equivalent thermal resistance (ETR) obtained by entransy dissipation rate. The constraints of total enveloping volume and fin material volume are considered. The results show that in the specified range of width ratio, the twice minimum ETR of the TAUSF can be yielded by an optimal width ratio and an optimal length ratio. In addition, comparing the optimal performance of the TAUSF with the counterpart of a T-shaped fin, the former sacrifices a small amount of heat transfer performance and its stiffness increases due to its structure with the bend end. The optimal structure of the TAUSF yielded from ETR minimization is conspicuously different with the counterpart yielded from maximum thermal resistance minimization. Comparing the thermal performances of the two optimal constructs, the ETR of the former optimal construct is declined by 10.58%, whereas the maximum thermal resistance is augmented by 5.22%. The former optimal construct can lead to the uniformity of temperature gradient and the reduction in thermal stress, and can guide the engineering designs of practical fins.

scholarly journals Numerical Study on Heat Transfer Performance in Packed Bed

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 414 ◽  
Author(s):  
Shicheng Wang ◽  
Chenyi Xu ◽  
Wei Liu ◽  
Zhichun Liu
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Transfer Process ◽  
Heat Transfer Performance ◽  
Numerical Study ◽  
Continuous Phase ◽  
Heat Transfer Process ◽  
Packed Beds ◽  
Transfer Performance ◽  
Entransy Dissipation

Packed beds are widely used in industries and it is of great significance to enhance the heat transfer between gas and solid states inside the bed. In this paper, numerical simulation method is adopted to investigate the heat transfer principle in the bed at particle scale, and to develop the direct enhanced heat transfer methods in packed beds. The gas is treated as continuous phase and solved by Computational Fluid Dynamics (CFD), while the particles are treated as discrete phase and solved by the Discrete Element Method (DEM); taking entransy dissipation to evaluate the heat transfer process. Considering the overall performance and entransy dissipation, the results show that, compared with the uniform particle size distribution, radial distribution of multiparticle size can effectively improve the heat transfer performance because it optimizes the velocity and temperature field, reduces the equivalent thermal resistance of convection heat transfer process, and the temperature of outlet gas increases significantly, which indicates the heat quality of the gas has been greatly improved. The increase in distribution thickness obviously enhances heat transfer performance without reducing the equivalent thermal resistance in the bed. The result is of great importance for guiding practical engineering applications.

Mass Nature of Heat and Its Application VII: Coupled Heat and Mass Transfer Optimization Based on the Entransy Theory

2010 ◽  
Author(s):  
Qun Chen ◽  
Moran Wang ◽  
Ning Pan ◽  
Zeng-Yuan Guo
Keyword(s):  
Mass Transfer ◽  
Thermal Resistance ◽  
Heat And Mass Transfer ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Entransy Dissipation ◽  
Cooling Systems ◽  
Entransy Theory ◽  
Transfer Processes ◽  
Mass Transfer Processes

Using the analogy between heat and mass transfer processes, the recently developed entransy theory is extended in this paper to tackle the coupled heat and mass transfer processes so as to analyze and optimize the performance of evaporative cooling systems. We first introduce a few new concepts including the moisture entransy, moisture entransy dissipation, and the thermal resistance in terms of the moisture entransy dissipation. Thereinafter, the moisture entransy is employed to describe the endothermic ability of a moist air. The moisture entransy dissipation on the other hand is used to measure the loss of the endothermic ability, i.e. the irreversibility, in the coupled heat and mass transfer processes, which consists of three parts: (1) the sensible heat entransy dissipation, (2) the latent heat entransy dissipation, and (3) the entransy dissipation induced by a temperature potential. And then the new thermal resistance, defined as the moisture entransy dissipation rate divided by the squared refrigerating effect output rate, is recommended as an index to effectively reflect the performance of the evaporative cooling system. Meanwhile, a minimum thermal resistance law for optimizing the evaporative cooling systems is developed. In the end, several direct and indirect evaporative cooling processes are analyzed to illustrate the applications of the proposed concepts.

scholarly journals Simulation analysis of heat transfer performance of heat sink with reduced material design

2020 ◽  
Vol 12 (5) ◽  
pp. 168781402092130
Author(s):  
Ya-Chu Chang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Thermal Resistance ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Electronic Device ◽  
Local Heating ◽  
Transfer Performance ◽  
Electronic Components ◽  
Thermal Reliability

The field of electronic device applications is becoming more and more extensive. With the development of science and technology and the improvement of the integration of electronic components, local heating is becoming more and more serious. If heat cannot be discharged immediately, it will cause heat to accumulate, causing the temperature of each component to exceed the limit. The reliability of electronic equipment is greatly reduced. Especially in important fields such as military and aerospace, the thermal reliability of electronic components is higher. The research results show that increasing the Reynolds number is helpful to reduce the overall temperature and thermal resistance of the heat sink, but the increase of the Reynolds number and the decrease of the thermal resistance value are gradually flat. The design concept of material reduction has a significant impact on processing and cost. The results of this article show that selecting the appropriate heat sink fins and matching the specific Reynolds number can effectively improve the heat transfer performance of the heat sink.

Effect of Filling Ratio and Tilt Angle on the Performance of a Mini-Loop Thermosyphon

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Trijo Tharayil ◽  
Neha Gitty ◽  
Lazarus Godson Asirvatham ◽  
Somchai Wongwises
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Wall Temperature ◽  
Tilt Angle ◽  
Heat Dissipation ◽  
Heat Transfer Performance ◽  
Electronics Cooling ◽  
Filling Ratio ◽  
Average Decrease ◽  
Heat Loads

The thermal behavior of a compact mini-loop thermosyphon is experimentally studied at different filling ratios (20%, 30%, 40%, 50%, and 70%) and tilt angles (0 deg, 30 deg, 45 deg, 60 deg, and 90 deg) for the heat loads of 20–300 W using distilled water as the heat pipe fluid. The presence of microfins at the evaporator results in an average decrease of 37.4% and 15.3% in thermal resistance and evaporator wall temperature, respectively, compared with the evaporator with a plain surface. Both filling ratio (FR) and tilt angle influence the heat transfer performance significantly, and the best performance of the mini-loop thermosyphon is obtained at their optimum values. The thermal resistance and thermal efficiency values lie in the ranges of 0.73–0.076 K/W and 65–88.3% for different filling ratios and tilt angles. Similarly, evaporator heat transfer coefficient and evaporator wall temperature show significant variation with changes in filling ratio and tilt angle. A combination of the optimum filling ratio and tilt angle shows a lowest thermal resistance of 0.076 K/W and a highest evaporator wall temperature of 68.6 °C, which are obtained at 300 W. The experimental results recommend the use of mini-loop thermosyphon at an optimum filling ratio for electronics cooling applications, which have a heat dissipation of 20–300 W.

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