scholarly journals Energy and Exergy Viability Analysis of Nanofluids As A Coolant for Microchannel Heat Sink

2019 ◽  
Vol 16 (1) ◽  
pp. 6090-6107
Author(s):  
S. Mukherjee ◽  
Purna Chandra Mishra ◽  
P. Chaudhuri
Keyword(s):  
Thermal Resistance ◽  
Weight Fraction ◽  
Constant Heat Flux ◽  
Heat Sinks ◽  
Exergy Loss ◽  
Simultaneous Increase ◽  
Substrate Thickness ◽  
Pumping Power ◽  
Rectangular Microchannel ◽  
Viability Analysis

The present paper aims to provide a theoretical analysis of energy, exergy loss and pumping power demand of water-based Al2O3, TiO2, CuO, SiC nanofluids flow through rectangular microchannel heat sinks under constant heat flux condition. The weight fraction of nanoparticles was varied from 0% to5%. Thermal resistance decreased with particle inclusion in the base fluid. Decease in thermal resistance and increase in microchannel efficiency was observed with the application of nanofluids. However, reduction in thermal resistance and rise in efficiency is more with Al2O3 –water and CuO-water nanofluids rather than TiO2-water and SiC-water nanofluids. Addition of nanoparticles in base fluids was found suitable for reducing thermal resistance and increasing efficiency of microchannel but at the same time, an increase in pumping power with the rise in weight fraction was also observed. The maximum reduction in thermal resistance with a simultaneous increase in thermal efficiency was observed using CuO-water nanofluids at 5% wt. fraction. The estimated exergy loss is relatively higher in CuO-water and Al2O3-water nanofluids than TiO2-water and SiC-water nanofluids. The rise in ambient temperature effectively reduces the exergy loss. Maximum exergy loss was obtained with CuO nanofluids at 5% wt. fraction while the minimum was observed with water. The effect of substrate thickness on efficiency and exergy loss was also estimated.

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.  

An analytical approach for optimal design of heat sinks under forced convection

2013 ◽  
Vol 3 (2) ◽  
Author(s):  
Antonio Miguel
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Transfer Rate ◽  
Analytical Approach ◽  
Constant Heat Flux ◽  
Heat Sinks ◽  
Pumping Power ◽  
Fluid Stream ◽  
Design Standards ◽  
Constant Heat

AbstractSaving energy is just as important as generating energy. In this paper, we seek an optimized structure that achieves a certain level of heat transfer rate under a minimum pumping power to drive the fluid stream. Constraints are specified by the flow regime (laminar and turbulent), admissible boundary conditions on the walls (prescribed temperature and constant heat flux), and design standards. The study will help designers with more effective basic tools for the conceptual design of system and in establishing proper operating procedures.

Thermal Performance Analysis of Hybrid Jet Impingement/Microchannel Cooling for Concentrated Photovoltaic (CPV) Cells

2016 ◽  
Author(s):  
Afzal Husain ◽  
Mohd Ariz ◽  
Nasser A. Al-Azri ◽  
Nabeel Z. H. Al-Rawahi ◽  
Mohd. Z. Ansari
Keyword(s):  
Thermal Resistance ◽  
Thermal Performance ◽  
Heat Sink ◽  
Three Dimensional ◽  
Jet Impingement ◽  
Constant Heat Flux ◽  
Pumping Power ◽  
High Concentration ◽  
Microchannel Cooling ◽  
Characteristic Relationship

The increase in the CPV temperature significantly reduces the efficiency of CPV system. To maintain the CPV temperature under a permissible limit and to utilize the unused heat from the CPVs, an efficient cooling and transportation of coolant is necessary in the system. The present study proposes a new design of hybrid jet impingements/microchannels heat sink with pillars for cooling densely packed PV cells under high concentration. A three-dimensional numerical model was constructed to investigate the thermal performance under steady state, incompressible and laminar flow. A constant heat flux was applied at the base of the substrate to imitate heated CPV surface. The effect of two dimensionless variables, i.e., ratios of standoff (distance from the nozzle exit to impingement surface) to jet diameter and jet pitch to jet diameter was investigated at several flow conditions. The performance of hybrid heat sink was investigated in terms of heat transfer coefficient, pressure-drop, overall thermal resistance and pumping power. The characteristic relationship between the overall thermal resistance and the pumping power was presented which showed an optimum design corresponding to S/Dj = 12 having lower overall thermal resistance and lower pumping power.

Improving Heat Transfer of Plate-Fin Heat Sinks Using Through Rod Configurations

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Mostafa A. H. Abdelmohimen ◽  
Salem Algarni ◽  
Khalid Almutairi ◽  
Gulam M. S. Ahmed ◽  
Kashif Irshad ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Thermal Resistance ◽  
Flow Direction ◽  
Heat Sinks ◽  
Pumping Power ◽  
Baseline Case ◽  
Flow Directions ◽  
Suction Flow ◽  
Impinging Flow

Abstract The performance of the heat sink has been investigated as using rods through its fins. The shear-stress transport k–ω model is selected to carry out this study. Two different flow directions have been studied. Four cases are represented, including the baseline case which has no rods through the fins. Two, four, and six rods are used through the fins. Thermal resistance, pumping power, and Nusselt number have been represented and discussed through this study. The results show that as the number of rods increases, the thermal resistance decreases while the required pumping power increases. The impinging flow direction shows higher performance as compared with the suction flow direction. As the Reynolds number increases, the Nusselt number increases for all studied cases. The optimum case along with the studied range of Reynolds number and number of rods is case-2 (has four rods through fins).

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.

scholarly journals Numerical Study of Double-Layered Microchannel Heat Sinks with Different Cross-Sectional Shapes

Entropy ◽  
2018 ◽  
Vol 21 (1) ◽  
pp. 16 ◽  
Author(s):  
Daxiang Deng ◽  
Guang Pi ◽  
Weixun Zhang ◽  
Peng Wang ◽  
Ting Fu
Keyword(s):  
Pressure Drop ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Numerical Study ◽  
Heat Sinks ◽  
High Heat Flux ◽  
Pumping Power ◽  
Cross Sectional ◽  
Prime Concern ◽  
Microchannel Heat Sinks

This work numerically studies the thermal and hydraulic performance of double-layered microchannel heat sinks (DL-MCHS) for their application in the cooling of high heat flux microelectronic devices. The superiority of double-layered microchannel heat sinks was assessed by a comparison with a single-layered microchannel heat sink (SL-MCHS) with the same triangular microchannels. Five DL-MCHSs with different cross-sectional shapes—triangular, rectangular, trapezoidal, circular and reentrant Ω-shaped—were explored and compared. The results showed that DL-MCHS decreased wall temperatures and thermal resistance considerably, induced much more uniform wall temperature distribution, and reduced the pressure drop and pumping power in comparison with SL-MCHS. The DL-MCHS with trapezoidal microchannels performed the worst with regard to thermal resistance, pressure drop, and pumping power. The DL-MCHS with rectangular microchannels produced the best overall thermal performance and seemed to be the optimum when thermal performance was the prime concern. Nevertheless, the DL-MCHS with reentrant Ω-shaped microchannels should be selected when pumping power consumption was the most important consideration.

Diamond Heat Sinks For High Temperature Electronics: Simuilation, And Thermal Analysis

1995 ◽  
Vol 416 ◽  
Author(s):  
Nickolaos Strifas ◽  
Aris Christou
Keyword(s):  
Thermal Conductivity ◽  
Thermal Analysis ◽  
High Temperature ◽  
Thermal Resistance ◽  
Substrate Material ◽  
Heat Sinks ◽  
Substrate Thickness ◽  
High Temperature Electronics ◽  
Die Attach ◽  
Heat Sink Design

ABSTRACTperformance that can be achieved by utilizing a diamond heat - sink design which minimizes junction - to - case thermal resistance. Effects of the thermal conductivity of the substrate material, the thermal conductivity of the die attach material, the substrate thickness, and the die attach thickness onl Ihe thermal resistance are addressed. The results indicate that the temperature increase could be 3 to 4 times less with diamond heat-sinks when compared to other materials.

Multi Layer Micro Pin-Fins Heat Sinks for Better Performance

2010 ◽  
Author(s):  
T. J. John ◽  
B. Mathew ◽  
H. Hegab
Keyword(s):  
Temperature Distribution ◽  
Thermal Resistance ◽  
Heat Sink ◽  
Single Layer ◽  
Heat Sinks ◽  
Substrate Thickness ◽  
Pin Fin ◽  
Micro Channels ◽  
Pin Fins ◽  
Overall Performance

This study numerically investigates the feasibility and advantages of using a multilayer pin-fin heat sink to increase the overall performance of the heat sink. For the purpose of determining overall performance of the pin-fin heat sink a figure of merit (FOM) term is introduced in this paper, which constituted of both the thermal resistance and the pumping power of the heat sink. Higher the FOM of a heat sink better is its overall performance. A computational fluid dynamics software CoventorWARE™ is used for the analysis of micro heat sink performance. A small portion of the entire heat sink is modeled in this study assuming repeatability towards both sides for the ease of analysis. The developed models consist of two sections, the substrate (silicon) and the fluid (water at 278K). A uniform heat flux is applied to the base of the heat sink. A single layer micro pin-fin heat sinks with same dimensions as of the multi layer heat sink was also modeled for the comparison purpose. Temperature distribution at five different locations from the inlet to the outlet section is also analyzed to study the temperature distribution over the heat sink. Circular pin-fins were used in both the multilayer and single layer micro heat sinks. Feasibility of using micro channels as the second layer was also investigated in this paper and it proved to have advantages over using pin-fin structures on both layers. A geometric optimization based on the substrate thickness of the second layer of the double layer heat sink showed that the substrate thickness of the second layer doesn’t have any effect on the overall thermal resistance of the heat sink.

Thermal Optimization of Plate-Fin Heat Sinks With Variable Fin Thickness

2010 ◽  
Author(s):  
Dong-Kwon Kim ◽  
Jaehoon Jung ◽  
Sung Jin Kim
Keyword(s):  
Thermal Resistance ◽  
Heat Sink ◽  
Vertical Direction ◽  
Volume Averaging ◽  
Heat Sinks ◽  
Averaging Theory ◽  
Pumping Power ◽  
Thermal Optimization ◽  
Model Based ◽  
Fin Thickness

In the present paper, we conducted thermal optimization of plate-fin heat sink with fin thickness varying in the vertical direction. The model based on volume averaging theory (VAT) was used for this optimization. It is shown that the thermal resistance of plate-fin heat sink is reduced by allowing the fin thickness to increase in the vertical direction. In the case of water-cooled heat sink, the thermal resistance decreases up to about 20%. The amount of the reduction increases as either pumping power increases or the length of heat sink decreases.

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