scholarly journals Thermal Resistance and Pressure Drop Minimization for a Micro-gap Heat Sink with Internal Micro-fins by Parametric Optimization of Operating Conditions

CFD Letters ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 100-112
Author(s):  
Shugata Ahmed ◽  
Erwin Sulaeman ◽  
Ahmad Faris Ismail ◽  
Muhammad Hasibul Hasan ◽  
Zahir Hanouf
Keyword(s):  
Heat Flux ◽  
Pressure Drop ◽  
Thermal Resistance ◽  
Void Fraction ◽  
Heat Sink ◽  
Operating Conditions ◽  
Superior Performance ◽  
Pumping Power ◽  
Two Phase ◽  
Total Thermal Resistance

In recent years, researchers are investigating several potential applications of two-phase flow in micro-gap heat sinks; electronic cooling is one of them. Further, internal micro-fins are used to enhance the heat transfer rate. However, the pressure drop penalty due to small gap height and fin surfaces is a major concern. Hence, minimization of thermal resistance and pressure drop is required. In this paper, effects of operating conditions, e.g., wall heat flux, pumping power, and inlet void fraction, on total thermal resistance and pressure drop in a micro-gap heat sink with internal micro-fins of rectangular and triangular profiles have been investigated by numerical analysis for the R-134a coolant. Furthermore, optimization of these parameters has been carried out by response surface methodology. Simulation results show that rectangular micro-fins show superior performance compared to triangular fins in reducing thermal resistance. Finally, for an optimum condition (7.1202×10-5 W pumping power, 1.2×107 Wm-2 heat flux, and 0.03 inlet void fraction), thermal resistance and pressure drop are reduced by 56.3% and 87.2%, respectively.

Two-Phase Stacked Microchannel Heat Sinks for Microelectronics Cooling

2005 ◽  
Vol 2 (2) ◽  
pp. 122-131
Author(s):  
Pradeep Hegde ◽  
K.N. Seetharamu ◽  
P.A. Aswatha Narayana ◽  
Zulkifly Abdullah
Keyword(s):  
Finite Element ◽  
Pressure Drop ◽  
Thermal Resistance ◽  
Heat Sink ◽  
Two Phase Flow ◽  
Heat Sinks ◽  
Phase Flow ◽  
Pumping Power ◽  
Two Phase ◽  
Microchannel Heat Sinks

Stacked microchannel heat sinks with two-phase flow have been analyzed using the Finite Element Method (FEM). The present method is a simple and practical approach for analyzing the thermal performance of single or multi layered microchannel heat sinks with either single or two-phase flow. A unique 10 noded finite element is used for the channel discretization. Two-phase thermal resistance, pressure drop and pumping power of single, double and triple stack microchannel heat sinks are determined at different base heat fluxes ranging from 150 W/cm2 to 300 W/cm2. The temperature distribution along the length of the microchannel is also plotted. It is found that stacked microchannel heat sinks with two-phase flow are thermally more efficient than two-phase single layer microchannel heat sinks, both in terms of thermal resistance and pumping power requirements. It is observed that the thermal resistance of a double stack microchannel heat sink with two-phase flow is about 40% less than that for a single stack heat sink. A triple stack heat sink yields a further 20% reduction in the thermal resistance and at the same time operates with about 30% less pumping power compared to a single stack heat sink. The effect of channel aspect ratio on the thermal resistance and pressure drop of stacked microchannel heat sinks with two-phase flow are also studied.

scholarly journals Optimization of nanofluid-cooled microchannel heat sink

2016 ◽  
Vol 20 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Ahmed Adham ◽  
Normah Mohd-Ghazali ◽  
Robiah Ahmad
Keyword(s):  
Thermal Resistance ◽  
Heat Sink ◽  
Volume Fraction ◽  
Operating Conditions ◽  
Microchannel Heat Sink ◽  
Pumping Power ◽  
Nsga Ii ◽  
Rectangular Microchannel ◽  
Total Thermal Resistance ◽  
Overall Performance

The optimization of a nanofluid-cooled rectangular microchannel heat sink is reported. Two nanofluids with volume fraction of 1 %, 3 %, 5 %, 7 % and 9 % are employed to enhance the overall performance of the system. An optimization scheme is applied consisting of a systematic thermal resistance model as an analysis method and the elitist non-dominated sorting genetic algorithm (NSGA-II). The optimized results showed that the increase in the particles volume fraction results in a decrease in the total thermal resistance and an increase in the pumping power. For volume fractions of 1 %, 3 %, 5 %, 7 % and 9 %, the thermal resistances were 0.072, 0.07151, 0.07075, 0.07024 and 0.070 [oK W-1] for the SiC-H2O while, they were 0.0705, 0.0697, 0.0694, 0.0692 and 0.069 [oK W-1] for the TiO2-H2O. The associated pumping power were 0.633, 0.638, 0.704, 0.757 and 0.807 [W] for the SiC-H2O while they were 0.645, 0.675, 0.724, 0.755 and 0.798 [W] for the TiO2-H2O. In addition, for the same operating conditions, the nanofluid-cooled system outperformed the water-cooled system in terms of the total thermal resistance (0.069 and 0.11 for nanofluid-cooled and water-cooled systems, respectively). Based on the results observed in this study, nanofluids should be considered as the future coolant for electronic devices cooling systems.

Optimization Design the Configuration Sizes of Multi-Layer Rectangle Micro-Channel Heat Sink

2013 ◽  
Vol 444-445 ◽  
pp. 1101-1106
Author(s):  
Li Feng Wang ◽  
Bao Dong Shao ◽  
He Ming Cheng ◽  
Ying He
Keyword(s):  
Pressure Drop ◽  
Thermal Resistance ◽  
Heat Sink ◽  
Optimization Design ◽  
High Heat ◽  
Micro Channel ◽  
Compact Structure ◽  
Total Thermal Resistance ◽  
High Heat Transfer ◽  
High Heat Transfer Coefficient

The configuration sizes of multi-layer rectangle micro-channel heat sink are optimized, which has been widely used to cool electronic chip for its high heat transfer coefficient and compact structure. Taking the thermal resistance and the pressure drop as goal functions, a binary-objective optimization model was proposed for the multi-layer rectangle micro-channel heat sink based on Sequential Quadratic Programming (SQP) method. The number of optimized micro-channel in width n1 and that in height n2 are 24 and 3, the width of optimized micro-channel Wc and fin Wf are 360 and 55μm, the height of optimized micro-channel Hc is 1000μm, and the corresponding total thermal resistance of the whole micro-channel heat sink is 1.5429 °C/W. The corresponding pressure drop is about 2.3454 Pa. When the velocity of liquid is larger than 0.3 m/s, the effect of change of velocity of liquid on the thermal resistance and pressure drop can be neglected.

Experimental Characterization of Two-Phase Cooling of Power Electronics in Thermosiphon and Forced Convection Modes

2021 ◽  
Vol 143 (3) ◽  
Author(s):  
Fabio Battaglia ◽  
Farah Singer ◽  
David C. Deisenroth ◽  
Michael M. Ohadi
Keyword(s):  
Heat Flux ◽  
Thermal Resistance ◽  
Power Electronics ◽  
Forced Convection ◽  
Heat Removal ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Two Phase ◽  
Total Thermal Resistance

Abstract In this paper, we present the results of an experimental study involving low thermal resistance cooling of high heat flux power electronics in a forced convection mode, as well as in a thermosiphon (buoyancy-driven) mode. The force-fed manifold microchannel cooling concept was utilized to substantially improve the cooling performance. In our design, the heat sink was integrated with the simulated heat source, through a single solder layer and substrate, thus reducing the total thermal resistance. The system was characterized and tested experimentally in two different configurations: the passive (buoyancy-driven) loop and the forced convection loop. Parametric studies were conducted to examine the role of different controlling parameters. It was demonstrated that the thermosiphon loop can handle heat fluxes in excess of 200 W/cm2 with a cooling thermal resistance of 0.225 (K cm2)/W for the novel cooling concept and moderate fluctuations in temperature. In the forced convection mode, a more uniform temperature distribution was achieved, while the heat removal performance was also substantially enhanced, with a corresponding heat flux capacity of up to 500 W/cm2 and a thermal resistance of 0.125 (K cm2)/W. A detailed characterization leading to these significant results, a comparison between the performance between the two configurations, and a flow visualization in both configurations are discussed in this paper.

On the Operational Parameters Effects on Two-Phase Pressure Drop Characteristics of Reentrant Copper Microchannels

2016 ◽  
Author(s):  
Daxiang Deng ◽  
Qingsong Huang ◽  
Yanlin Xie ◽  
Wei Zhou ◽  
Xiang Huang ◽  
...  
Keyword(s):  
Heat Flux ◽  
Pressure Drop ◽  
Mass Flux ◽  
Heat Sink ◽  
Flow Boiling ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Two Phase ◽  
Cooling Systems ◽  
Phase Pressure

Two-phase boiling in advanced microchannel heat sinks offers an efficient and attractive solution for heat dissipation of high-heat-flux devices. In this study, a type of reentrant copper microchannels was developed for heat sink cooling systems. It consisted of 14 parallel Ω-shaped reentrant copper microchannels with a hydraulic diameter of 781μm. Two-phase pressure drop characteristics were comprehensively accessed via flow boiling tests. Both deionized water and ethanol tests were conducted at inlet subcooling of 10°C and 40°C, mass fluxes of 125–300kg/m2·s, and a wide range of heat fluxes and vapor qualities. The effects of heat flux, mass flux, inlet subcoolings and coolants on the two-phase pressure drop were systematically explored. The results show that the two-phase pressure drop of reentrant copper microchannels generally increased with increasing heat fluxes and vapor qualities. The role of mass flux and inlet temperatures was dependent on the test coolant. The water tests presented smaller pressure drop than the ethanol ones. These results provide critical experimental information for the development of microchannel heat sink cooling systems, and are of considerable practical relevance.

Multi-Objective Optimization Design of Multi-Layer Rectangle Micro-Channel Heat Sink for Single-Phase Flow and Heat Transfer

2013 ◽  
Vol 709 ◽  
pp. 286-291 ◽  
Author(s):  
Li Feng Wang ◽  
Bao Dong Shao ◽  
He Ming Cheng
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Thermal Resistance ◽  
Heat Sink ◽  
Optimization Design ◽  
High Heat ◽  
Micro Channel ◽  
Compact Structure ◽  
Total Thermal Resistance ◽  
High Heat Transfer

The purpose of this paper is to optimize the structural sizes of multi-layer rectangle micro-channel heat sink, which has been widely used to cool electronic chip for its high heat transfer coefficient and compact structure. Taking the thermal resistance and the pressure drop as goal functions, a binary-objective optimization model was proposed for the multi-layer rectangle micro-channel heat sink based on Sequential Quadratic Programming (SQP) method. The number of optimized micro-channel in width n1 and that in height n2 are 21 and 7, the width of optimized micro-channel Wc and fin Wf are 340 and 130μm, the height of optimized micro-channel Hc is 415μm, and the corresponding total thermal resistance of the whole micro-channel heat sink is 1.3354 °C/W. The corresponding pressure drop is about 1.3377 Pa. When the velocity of liquid is larger than 0.3 m/s, the effect of change of velocity of liquid on the thermal resistance and pressure drop can be neglected.

Experimental Study on Two-Phase Heat Transfer of FC-72 in Microchannels Heat Sink

2009 ◽  
Author(s):  
Xiao Hu ◽  
Guiping Lin ◽  
Hongxing Zhang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Flow Rate ◽  
Mass Flux ◽  
Heat Sink ◽  
Heat Fluxes ◽  
High Mass ◽  
Two Phase ◽  
Two Phase Heat Transfer

A closed-loop two-phase microchannels cooling system using a micro-gear pump was built in this paper. The microchannels heat sink was made of oxygen-free copper, and 14 parallel microchannels with the dimension of 0.8mm(W)×1.5mm(D)×20mm(L) were formed by electric spark drilling followed by linear cutting which separated the channels from each other. The heat transfer performance was evaluated by the fluid temperature, the pressure drop across the micro-channels and the volumetric flow rate. Experiments were performed with refrigerant FC-72 which spanned the following conditions: initial pressure of Pin = 73 kPa, mass velocity of G = 94 – 333 kg/m2s, outlet quality of xe,out = 0 – superheat and heat flux of q″= 25–140 W/cm2. The result showed that, the maximum heat flux achieved 96 W/cm2, as the heating surface temperature was kept below 85 °C and critical heat flux occurred in the condition of low flow rate. Average two-phase heat transfer coefficients increased with the heat flux at low mass flux (G = 94 and 180 kg/m2s) and all heat fluxes, high mass flux (G = 333 kg/m2s) and all heat fluxes, and moderate mass fluxes (G = 224kg/m2s) under low and moderate heat fluxes (q″<110 W/cm2 for G = 224 kg/m2s), which was a feature of nucleate boiling mechanism. Pressure drop through microchannels heat sink was found to be below 4kPa.

PERFORMANCE OF A MULTI-STACK MICROCHANNEL HEAT SINK

2016 ◽  
Vol 78 (10-2) ◽  
Author(s):  
Nik Mohamad Sharif ◽  
Normah Mohd Ghazali
Keyword(s):  
Thermal Resistance ◽  
Heat Sink ◽  
Cooling System ◽  
Heat Fluxes ◽  
Width Ratio ◽  
Optimum Number ◽  
Microchannel Heat Sink ◽  
Objective Functions ◽  
Pumping Power ◽  
Total Thermal Resistance

The usage of a very large scale integrated circuits generate high heat fluxes and require an effective cooling system. A microchannel heat sink (MCHS) is one of the reliable cooling systems that had been applied. In terms of performance, a MCHS can be appraised by obtaining low total thermal resistance and pumping power. However, as the total thermal resistance decreases, the pumping power will increase. A few studies have been focused on the minimization of the thermal resistance and pumping power of a multi-stack MCHS. Optimization of two objective functions which are the total thermal resistance and pumping power has been done by using genetic algorithm. It is demonstrated that both objective functions can be minimized by optimizing two design variables which are the channel aspect ratio, , and wall width ratio, . It was found that the usage of a stacked configuration for the MCHS is able to reduce the total thermal resistance. From the optimization, it was found that the optimum number of stacks that can be implemented is three. With the three-stack configuration, the total thermal resistance found is 0.1180 K/W which is 21.8% less compared to the single-stack MCHS. However, the pumping power needed for the three-stack MCHS is increased by 0.17 % compared to single-stack which is 0.7535 W.

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