scholarly journals Flow and Heat Transfer Performances of Liquid Metal Based Microchannel Heat Sinks under High Temperature Conditions

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 95
Author(s):  
Tao Wu ◽  
Lizhi Wang ◽  
Yicun Tang ◽  
Chao Yin ◽  
Xiankai Li
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Liquid Metal ◽  
Cross Section ◽  
Great Influence ◽  
Heat Sinks ◽  
Working Fluid ◽  
Transfer Model ◽  
Flow And Heat Transfer ◽  
Microchannel Heat Sinks

Developments in applications such as rocket nozzles, miniature nuclear reactors and solar thermal generation pose high-density heat dissipation challenges. In these applications, a large amount heat must be removed in a limited space under high temperature. In order to handle this kind of cooling problem, this paper proposes liquid metal-based microchannel heat sinks. Using a numerical method, the flow and heat transfer performances of liquid metal-based heat sinks with different working fluid types, diverse microchannel cross-section shapes and various inlet velocities were studied. By solving the 3-D steady and conjugate heat transfer model, we found that among all the investigated cases, lithium and circle were the most appropriate choices for the working fluid and microchannel cross-section shape, respectively. Moreover, inlet velocity had a great influence on the flow and heat transfer performances. From 1 m/s to 9 m/s, the pressure drop increased as much as 65 times, and the heat transfer coefficient was enhanced by about 74.35%.

Enhanced Thermal Transport in Microchannel Using Oblique Fins

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Y. J. Lee ◽  
P. S. Lee ◽  
S. K. Chou
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Enhancement ◽  
Heat Sink ◽  
Heat Sinks ◽  
Maximum Temperature ◽  
Working Fluid ◽  
Microchannel Heat Sink ◽  
Transfer Enhancement ◽  
Microchannel Heat Sinks

Sectional oblique fins are employed, in contrast to continuous fins in order to modulate the flow in microchannel heat sinks. The breakage of a continuous fin into oblique sections leads to the reinitialization of the thermal boundary layer at the leading edge of each oblique fin, effectively reducing the boundary layer thickness. This regeneration of entrance effects causes the flow to always be in a developing state, thus resulting in better heat transfer. In addition, the presence of smaller oblique channels diverts a small fraction of the flow into adjacent main channels. The secondary flows created improve fluid mixing, which serves to further enhance heat transfer. Both numerical simulations and experimental investigations of copper-based oblique finned microchannel heat sinks demonstrated that a highly augmented and uniform heat transfer performance, relative to the conventional microchannel, is achievable with such a passive technique. The average Nusselt number, Nuave, for the copper microchannel heat sink which uses water as the working fluid can increase as much as 103%, from 11.3 to 22.9. Besides, the augmented convective heat transfer leads to a reduction in maximum temperature rise by 12.6 °C. The associated pressure drop penalty is much smaller than the achieved heat transfer enhancement, rendering it as an effective heat transfer enhancement scheme for a single-phase microchannel heat sink.

scholarly journals Experimental Study and Conjugate Heat Transfer Simulation of Turbulent Flow in a 90° Curved Square Pipe

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 94
Author(s):  
Guanming Guo ◽  
Masaya Kamigaki ◽  
Qiwei Zhang ◽  
Yuuya Inoue ◽  
Keiya Nishida ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Turbulent Flow ◽  
Cross Section ◽  
Conjugate Heat Transfer ◽  
Air Flow ◽  
Temperature Fields ◽  
Spatial Average ◽  
Flow And Heat Transfer ◽  
Curved Pipes

This paper discusses the turbulent flow and heat transfer from a uniform air flow with high temperature to the outside through a 90° curved square pipe. Both conjugate heat transfer (CHT) simulation and experiments of temperature field measurements at cross sections of the pipe are performed. A straight pipe is investigated and compared with the 90° curved pipe. The temperature of the air flow at the inlet of the pipe is set at 402 K, and the corresponding Reynolds number is approximately 6 × 104. To obtain the spatial average temperature at each cross section, the temperature fields are measured along the streamwise of the pipes and in the circumferential direction using thermocouples at each cross section from the inlet to the outlet of both the straight and curved pipes. Furthermore, the simulation is performed for turbulent flow and heat transfer inside the pipe wall using the Re-normalization group (RNG) k-ε turbulence model and CHT method. Both the experimental and numerical results show that the curvature of the pipe result in a deviation and impingement in the high-temperature core and a separation between the wall and air, resulting in a secondary flow pattern of the temperature distribution.

Flow and Heat Transfer Analysis in Diverse Microchannel Geometries

2006 ◽  
Author(s):  
J. Garci´a-Gonza´lez ◽  
A. Herna´ndez-Guerrero ◽  
C. Rubio-Arana ◽  
F. Solorio-Ordaz
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Electronic Devices ◽  
Constant Heat Flux ◽  
Heat Sinks ◽  
Work Flow ◽  
Heat Transfer Analysis ◽  
Working Fluid ◽  
Flow And Heat Transfer ◽  
Current Contact

In this paper an analysis of the fluid flow and the heat transfer in the next generation micro-sized heat sinks is presented. The analysis includes three different geometries for the channels of the heat sinks: rectangular, triangular and trapezoidal, with water as the cooling work flow. A constant heat flux typical of the current high-intensive computational chips (such as the current Pentium chips) is applied at the bottom of the heat sink in a small 1 cm × 1 cm area, an area also typical of the current contact area between electronic devices and the heat dissipaters. The analysis aims to determine the effect of geometry at microscopic scales. It is found that the temperature at the bottom of the dissipater increases approximately in a linear fashion and that by increasing the Reynolds number this temperature decreases. On the contrary, by having a decay in the Reynolds number the temperature of the working fluid increases, bringing a decrease in the viscosity allowing in turn a decrease in the friction losses since the friction coefficient decreases.

Numerical Simulation of Operating Performance of Heat Exchangers in a Residential Split Air-Conditioner

2011 ◽  
Vol 250-253 ◽  
pp. 3913-3918 ◽  
Author(s):  
Shun Yu Su ◽  
Tian Tian ◽  
Jian Chen
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Exchangers ◽  
Great Influence ◽  
Working Fluid ◽  
Air Conditioner ◽  
Two Phase ◽  
Air Conditioning System ◽  
Flow And Heat Transfer ◽  
Phase Fluid

The mechanism of fluid flow and heat transfer in the heat exchangers was investigated in this paper. Using R22 as the working fluid, the steady distributed parameter models of condenser and evaporator in a residential split air-conditioner were established based on thermophysical laws such as mass, momentum and energy conservation equations. The regions of two-phase fluid and superheated gas in evaporator and the regions of superheated gas, two-phase fluid and subcooled liquid in condenser were respectively simulated under designed conditions of air-conditioning system. Based on the calculated results, the flow and heat transfer performances of heat exchangers were analyzed. The results show that the two-phase fluid regions in both evaporator and condenser have great influence on the fluid flow and heat transfer performances in it.

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