scholarly journals Constructal Optimization of Rectangular Microchannel Heat Sink with Porous Medium for Entropy Generation Minimization

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1528
Author(s):  
Wenlong Li ◽  
Zhihui Xie ◽  
Kun Xi ◽  
Shaojun Xia ◽  
Yanlin Ge
Keyword(s):  
Heat Flux ◽  
Aspect Ratio ◽  
Entropy Generation ◽  
Heat Sink ◽  
Width Ratio ◽  
Microchannel Heat Sink ◽  
Rectangular Microchannel ◽  
Entropy Generation Minimization ◽  
Aspect Ratios ◽  
Length Width

A model of rectangular microchannel heat sink (MCHS) with porous medium (PM) is developed. Aspect ratio of heat sink (HS) cell and length-width ratio of HS are optimized by numerical simulation method for entropy generation minimization (EGM) according to constructal theory. The effects of inlet Reynolds number (Re) of coolant, heat flux on bottom, porosity and volume proportion of PM on dimensionless entropy generation rate (DEGR) are analyzed. From the results, there are optimal aspect ratios to minimize DEGR. Given the initial condition, DEGR is 33.10% lower than its initial value after the aspect ratio is optimized. With the increase of Re, the optimal aspect ratio declines, and the minimum DEGR drops as well. DEGR gets larger and the optimal aspect ratio remains constant with the increasing of heat flux on bottom. For the different volume proportion of PM, the optimal aspect ratios are diverse, but the minimum DEGR almost stays unchanged. The twice minimized DEGR, which results from aspect ratio and length-width ratio optimized simultaneously, is 10.70% lower than the once minimized DEGR. For a rectangular bottom, a lower DEGR can be reached by choosing the proper direction of fluid flow.

THERMAL AND HYDRODYNAMIC PERFORMANCE OF A MICROCHANNEL HEAT SINK COOLED WITH CARBON NANOTUBES NANOFLUID

2016 ◽  
Vol 78 (10-2) ◽  
Author(s):  
Nik Ahmad Faiz Nik Mazlam ◽  
Normah Mohd-Ghazali ◽  
Thierry Mare ◽  
Patrice Estelle ◽  
Salma Halelfadl
Keyword(s):  
Thermal Resistance ◽  
Heat Sink ◽  
Operating Temperature ◽  
Heat Removal ◽  
Hydrodynamic Performance ◽  
Spherical Particles ◽  
Microchannel Heat Sink ◽  
Pumping Power ◽  
Rectangular Microchannel ◽  
Aspect Ratios

The microchannel heat sink (MCHS) has been established as an effective heat removal system in electronic chip packaging. With increasing power demand, research has advanced beyond the conventional coolants of air and water towards nanofluids with their enhanced heat transfer capabilities. This research had been carried out on the optimization of the thermal and hydrodynamic performance of a rectangular microchannel heat sink (MCHS) cooled with carbon nanotube (CNT) nanofluid, a coolant that has recently been discovered with improved thermal conductivity. Unlike the common nanofluids with spherical particles, nanotubes generally come in cylindrical structure characterized with different aspect ratios. A volume concentration of 0.1% of the CNT nanofluid is used here; the nanotubes have an average diameter and length of 9.2 nm and 1.5 mm respectively. The nanofluid has a density of 1800 kg/m3 with carbon purity 90% by weight having lignin as the surfactant. The approach used for the optimization process is based on the thermal resistance model and it is analyzed by using the non-dominated sorting multi-objective genetic algorithm. Optimized outcomes include the channel aspect ratio and the channel wall ratio at the optimal values of thermal resistance and pumping power. The optimized results show that, at high operating temperature of 40°C the use of CNT nanofluid reduces the total thermal resistance by 3% compared to at 20°C and consequently improve the thermal performance of the fluid. In terms of the hydrodynamic performance, the pumping power is also being reduced significantly by 35% at 40°C compared to the lower operating temperature.  

Circular Microchannel Heat Sink Optimization Using Entropy Generation Minimization Method

2020 ◽  
Vol 45 (4) ◽  
pp. 333-342
Author(s):  
Krishan Kumar ◽  
Rajan Kumar ◽  
Rabinder Singh Bharj
Keyword(s):  
Entropy Generation ◽  
Flow Rate ◽  
Heat Sink ◽  
Numerical Study ◽  
Bejan Number ◽  
Optimum Number ◽  
Microchannel Heat Sink ◽  
Heat Flow Rate ◽  
Entropy Generation Number ◽  
Entropy Generation Minimization

AbstractThe performance of the microchannel heat sink (MCHS) in electronic applications needs to be optimized corresponding to the number of channels (N). In this study optimization of the number of channels corresponding to the diameter of the microchannel ({D_{N}}) using an entropy generation minimization approach is achieved for the MCHS used in electronic applications. The numerical study is performed for constant total heat flow rate ({\dot{q}_{tot}}) and total mass flow rate ({\dot{m}_{tot}}). The results indicate that the dominance of frictional entropy generation ({S_{gen,Fr}}) increases with the reduction in diameter. However, the entropy generation due to heat transfer ({S_{gen,HT}}) decreases with the reduction in diameter. Therefore, the optimum diameter ({D^{\ast }}) is calculated corresponding to the minimum total entropy generation ({S_{gen,total}}) for the optimum number of channels ({N^{\ast }}). Furthermore, the entropy generation number ({N_{S}}) and Bejan number (Be) are also calculated.

Numerical Investigation of Heat Transfer Characteristics of a Novel Wavy-Tapered Microchannel Heat Sink

2016 ◽  
Author(s):  
Ahmed Eltaweel ◽  
Abdulla Baobeid ◽  
Brian Tompkins ◽  
Ibrahim Hassan
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Heat Sink ◽  
Substrate Surface ◽  
Microchannel Heat Sink ◽  
Aspect Ratios ◽  
Wavy Channels ◽  
Channel Configuration

In the present study, a multi-variable comparative study of the effect of microchannel heat sink configurations on their thermal performance is conducted by numerically simulating three-dimensional fluid flow and heat transfer in multiple microchannel heat sink configurations. Thermal analysis is performed to investigate a novel wavy-tapered channel configuration of microchannel heat sinks with directionally alternating coolant flow for high-end electronics cooling. Simulations were conducted at different tapering and aspect ratios, focusing on how effectively previously proven geometric enhancements combine with one another in novel ways. Results confirmed the superiority of wavy channels over straight channels due to the development of the secondary flow (Dean Vortices), which enhance the advection mixing and consequently the overall heat sink thermal performance. Moreover, width-tapering of the wavy channel showed improved channel performance in terms of thermal resistance compared to untapered wavy channels. Almost 10% improvement in thermal resistance is obtained with width tapering. Also, the thermal performance showed a strong dependency on channel aspect ratio. Overall performance suggests that optimum tapering and aspect ratio conditions exist. The numerical investigations are then extended to novel heat sink design includes wavy tapered microchannels with directionally alternating flow to improve heat sink thermal performance. A 15% reduction in thermal resistance and highly improved substrate surface temperature distribution uniformity are obtained using alternating flow compared to corresponding parallel flow channels.

scholarly journals A Triangular Double Layer Microchannel Heat Sink: Effect of Parallel and Counter Flow

2015 ◽  
Vol 1115 ◽  
pp. 433-439
Author(s):  
Hazli Manaf ◽  
Shugata Ahmed ◽  
Mirghani I. Ahmed ◽  
M.N.A. Hawlader
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Heat Sink ◽  
Numerical Study ◽  
Parallel Flow ◽  
Microchannel Heat Sink ◽  
Counter Flow ◽  
Flow Configuration ◽  
Aspect Ratios ◽  
Channel Aspect Ratio

A numerical study is conducted by using ANSYS CFX 14.5, a commercial computational fluid dynamics program to predict the thermal performance of a counter and parallel flow on triangular double layered microchannel heat sink for various channel aspect ratios. Findings reveal that the counter flow configuration leads to a better heat transfer performance for low channel aspect ratio (α < 4) and higher Reynolds Number (Re > 700). For the parallel flow configuration, improved performance is normally shown when channel aspect ratio, α is more than 4 and lower Reynolds Number (Re < 700).

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