Microchannel Heat Sink for Thermal Management of Concentrated Photovoltaic Cells

2021 ◽  
Author(s):  
Dinumol Varghese ◽  
Ahmed Sefelnasr ◽  
Mohsen Sherif ◽  
Fadi Alnaimat ◽  
Bobby Mathew
Keyword(s):  
Reynolds Number ◽  
Thermal Resistance ◽  
Thermal Management ◽  
Heat Sink ◽  
Stokes Equations ◽  
Photovoltaic Cells ◽  
Navier Stokes ◽  
Microchannel Heat Sink ◽  
Pumping Power ◽  
Energy Equations

Abstract This article conceptualizes a single-phase microchannel heat sink for thermal management of concentrated photovoltaic cells; details of the model-based parametric study that is carried out on the heat sink is also detailed in this article. The heat sink consists of multiple serpentine microchannels. The mathematical model consists of continuity equation, Navier-Stokes equations and energy equations. Fluent module of Ansys Workbench is used for solving the model. The performance of the device is quantified in terms two metrics such as thermal resistance and pumping power. Studies are done for Reynolds number ranging from 100 to 1250. It is observed that increase in Reynolds number decreases the thermal resistance while increasing the pumping power irrespective of the geometric parameters of the heat sink. Decrease in hydraulic diameter of the microchannel reduces the thermal resistance while increasing the pumping power. Increase in the length segment of the serpentine microchannel increases and decreases the thermal resistance and pumping power, respectively. With increase in the offset width of the serpentine microchannel the thermal resistance and pumping power decreases and increases, respectively.

Evaluation of Various Channel Shapes of a Microchannel Heat Sink

2016 ◽  
Vol 24 (03) ◽  
pp. 1650018 ◽  
Author(s):  
Aatif Ali Khan ◽  
Kwang-Yong Kim
Keyword(s):  
Reynolds Number ◽  
Thermal Resistance ◽  
Heat Sink ◽  
Stokes Equations ◽  
Hydraulic Diameter ◽  
Navier Stokes ◽  
Average Height ◽  
Microchannel Heat Sink ◽  
Navier Stokes Equations ◽  
Number Range

Thermal and hydraulic performances of various geometric shapes of a microchannel heat sink were evaluated numerically using Navier–Stokes equations. A heat sink comprised of a [Formula: see text][Formula: see text]cm2 silicon wafer was investigated with water as the cooling fluid. The performances of seven microchannel shapes were compared at the same microchannel hydraulic diameter and the same average height of the bottom silicon substrate. The thermal resistance, friction coefficient, and Nusselt number were calculated for a Reynolds number range of 50 to 500. The results show that an inverse trapezoidal shape gives the lowest thermal resistance for a Reynolds number up to 300. The values of [Formula: see text]Re are almost similar for all the shapes because of the constant hydraulic diameter.

Thermal Performance and Pressure Drop of Galinstan-Based Microchannel Heat-Sink for High Heat-Flux Thermal Management

2015 ◽  
Author(s):  
Yoshikazu Hayashi ◽  
Navid Saneie ◽  
Yoon Jo Kim ◽  
Jong-Hoon Kim
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Pressure Drop ◽  
Thermal Resistance ◽  
Specific Heat ◽  
Thermal Management ◽  
Heat Sink ◽  
Working Fluid ◽  
Microchannel Heat Sink ◽  
Pumping Power

We numerically investigated a novel galinstan-based microfluidic heat-sink. Galinstan is an eutectic alloys of gallium, indium, and tin. The thermal conductivity of galinstan is ∼27 times that of water, while the dynamic viscosity is only twice of water. Thus, heat transfer coefficient can be remarkably enhanced with a small penalty of pumping power. However, the specific heat of galinstan is significantly lower than that of water, which will inevitably undermine the cooling capability by increasing fluid outlet temperature (i.e., increase of caloric thermal management) and/or flow rate. As an alternative, therefore, galinstan/water heterogeneous mixture was proposed as a working fluid and the cooling performance was numerically explored with varying volume composition of galinstan. Effective medium theory for heterogeneous medium was used to evaluate the thermal conductivity of the mixture. The viscosity change with respect to the volume composition was also predicted considering both the viscosity of dispersed phase and interaction between the droplets. Classical models were used for the mixture density and specific heat calculations. Heat transfer and pressure drop characteristics of laminar flow through a silicon microchannel heat-sink was simulated using Fluent. The length and width of the channel array are 10 mm and 9.5 mm, respectively. The cross-sectional area of each channel is 300 μm × 300 μm and the spacing between channels is 100 μm. The heat dissipation was 50 W and the pumping power was fixed at 5 mW for the comparison between the varying galinstan/water compositions. The results showed that more than 30% of the thermal resistance enhancement was attainable using the novel working fluid. Due to the compromise between the convective thermal resistance (effect of thermal conductivity) and the caloric thermal resistance (effect of viscosity and specific heat), the lowest junction temperature was marked at the galinstan composition of ∼35% by volume.

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.  

S-Shaped Pin-Fins for Enhancement of Overall Performance of the Pin-Fin Heat Sink

2010 ◽  
Author(s):  
T. J. John ◽  
B. Mathew ◽  
H. Hegab
Keyword(s):  
Reynolds Number ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Heat Sink ◽  
Heat Sinks ◽  
Uniform Heat Flux ◽  
Pumping Power ◽  
Pin Fin ◽  
Pin Fins ◽  
Overall Performance

In this paper the authors are studying the effect of introducing S-shaped pin-fin structures in a micro pin-fin heat sink to enhance the overall thermal performance of the heat sinks. For the purpose of evaluating the overall thermal performance of the heat sink a figure of merit (FOM) term comprising both thermal resistance and pumping power is introduced in this paper. An optimization study of the overall performance based on the pitch distance of the pin-fin structures both in the axial and the transverse direction, and based on the curvature at the ends of S-shape fins is also carried out in this paper. The value of the Reynolds number of liquid flow at the entrance of the heat sink is kept constant for the optimization purpose and the study is carried out over a range of Reynolds number from 50 to 500. All the optimization processes are carried out using computational fluid dynamics software CoventorWARE™. The models generated for the study consists of two sections, the substrate (silicon) and the fluid (water at 278K). The pin fins are 150 micrometers tall and the total structure is 500 micrometer thick and a uniform heat flux of 500KW is applied to the base of the model. The non dimensional thermal resistance and nondimensional pumping power calculated from the results is used in determining the FOM term. The study proved the superiority of the S-shaped pin-fin heat sinks over the conventional pin-fin heat sinks in terms of both FOM and flow distribution. S-shaped pin-fins with pointed tips provided the best performance compared to pin-fins with straight and circular tips.

Numerical Modelling of Nanofluid Heat Transfer Inside a Microchannel Heat Sink

2012 ◽  
Author(s):  
Benjamin Rimbault ◽  
Cong Tam Nguyen ◽  
Nicolas Galanis
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Sink ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Convective Heat Transfer Coefficient ◽  
Microchannel Heat Sink ◽  
Pumping Power ◽  
Particle Volume ◽  
Number Range

The problem of laminar flow and heat transfer of water-based nanofluids inside a 3D-microchannel heat sink was numerically investigated, considering temperature-dependent fluids properties. Results, obtained for the 250–2000 Reynolds number range, show that an important enhancement of surface convective heat transfer coefficient can be achieved by increasing the particle volume fraction. For given Reynolds number and particle fraction, a highest heat transfer enhancement is obtained using CuO-water nanofluid. However, the use of nanofluids considerably increases the wall friction and consequently the pumping power. The ‘heat transferred to fluid/pumping power’ ratio was calculated for nanofluids. For given Reynolds number and particle volume fraction, such a ratio was found lowest for CuO-water nanofluid, while alumina-water nanofluids provide similar results.

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.

Shape Optimization of a Microchannel Heat Sink with Phase Change

2013 ◽  
Vol 284-287 ◽  
pp. 919-924
Author(s):  
Man Woong Heo ◽  
Dae Woong Choi ◽  
Kwang Yong Kim
Keyword(s):  
Shape Optimization ◽  
Thermal Resistance ◽  
Phase Change ◽  
Objective Function ◽  
Heat Sink ◽  
Surrogate Model ◽  
Stokes Equations ◽  
Uniform Heat Flux ◽  
Microchannel Heat Sink ◽  
Optimal Point

Optimization of a microchannel heat sink has been performed based on the analyses of fluid flow and heat transfer with phase change using three-dimensional Reynolds-averaged Navier-Stokes equations. The uniform heat flux condition is applied at the bottom of the heat sink. Three design variables, viz. ratio of microchannel width to height of the heat sink, ratio of fin height to heat sink height, and ratio of fin width to height of the heat sink are selected for the shape optimization. Latin hypercube sampling was used to determine the training points as a design of experiment, and the surrogate model is constructed using the objective function values at the training points. Sequential quadratic programming is used to search for the optimal point from the constructed surrogate model. The thermal resistance is set as the objective function. It was found that the thermal resistance increased with increasing ratios of the microchannel width-to-height of the heat sink and fin height to heat sink height, while the thermal resistance decreased with increasing ratio of the fin width-to-height of the heat sink. Through the optimization, the thermal resistance has been decreased by 37.3% compared to the reference geometry.

scholarly journals Numerical investigation of using different arrangement of fin slides on the plate-fin heat sink performance

2021 ◽  
pp. 65-65
Author(s):  
Mostafa Abdelmohimen ◽  
Khalid Almutairi ◽  
Mohamed Elkotb ◽  
Hany Abdelrahman ◽  
Salem Algarni
Keyword(s):  
Reynolds Number ◽  
Thermal Resistance ◽  
Heat Sink ◽  
Parallel Flow ◽  
Heat Sinks ◽  
Pumping Power ◽  
Staggered Arrangement ◽  
Flow Directions ◽  
High Reynolds ◽  
Impinging Flow

Cutting fins of the plate heat sinks into multi-numbers of slides instead of one slide fin is a technique to improve the performance of the heat sink. One, two, three, and four slides have been studied numerically. The slides have been arranged in staggered arrangement. The study has been carried out on two different flow directions (impinging and parallel). The performance of the heat sink under the studied conditions has been represented through calculation of heat sink effectiveness, thermal resistance, pressure drop, pumping power, and Nusselt number. The studied range of Reynolds number is from 1333 to 5334. The results show that parallel flow gives lower thermal resistance than impinging flow for all studied cases. The pumping power required for high Reynolds number in case of parallel flow increases by around 155% with case-4 (four slides) as compared by case-1 (one slide). While it is slightly affected in case of impinging flow, using three slides with impinging flow represents an acceptable decrement in thermal resistance with low change in the required pumping power. In case of parallel flow, the resulting change in the heat sink performance, as the number of slides increases, is not proportional to the large increase in the pumping power.

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.

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