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.

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.

Solving Thermal Issues in a Three-Dimensional-Stacked-Quad-Core Processor by Microprocessor Floor Planning, Microchannel Cooling, and Insertion of Through-Silicon-Vias

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Anjali Chauhan ◽  
Bahgat Sammakia ◽  
Furat F. Afram ◽  
Kanad Ghose ◽  
Gamal Refai-Ahmed ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Heat Sink ◽  
Hot Spot ◽  
Three Dimensional ◽  
Memory Access ◽  
Microchannel Heat Sink ◽  
Multicore System ◽  
Floor Planning ◽  
Microchannel Cooling ◽  
Silicon Vias

The electronics industry is heading toward the three-dimensional (3D) microprocessor to cope with higher computing workloads. The 3D stacking of the processor and the memory components reduces the communication delay in multicore system-on-a-chip (SoCs), owing to reduced system size and shorter interconnects. The shorter interconnects in a multicore system lowers the memory access latencies and contributes to improvements in memory access bandwidth. The shorter interconnects in stacked architectures also enables small drivers for interconnections which further reduce interconnection-level-energy dissipations. On the down side, the 3D-stacked architectures have high thermal resistance, which in conjunction with poor thermal management techniques, poses a thermal threat to the reliability of the device. This paper establishes the significance of the microprocessor floor planning and single-phase microchannel cooling for solving the thermal issues arising in the 3D-stacked-quad-core processor. The 3D-stacked-quad-core processor considered in this study comprises of symmetric nonuniformly powered quad-core processor, liquid-cooled microchannel heat sink, dynamic random access memory (DRAM), thermal interface material (TIM), and heat spreader. The electrical through-silicon-vias (TSVs) between the processor and DRAM serve as interconnects, while the thermal TSVs reduce the internal thermal resistance. The effective cooling of the 3D-stacked-quad-core processor depends on the TSVs, quad-core layout and the optimized design of the microchannel heat sink for the desired coolant. The microchannel cooling of the 3D-stacked processor is done both by planar flow and impingement flow. The thermal efficiency of the cooling techniques is evaluated on the basis of hot spot temperature, hot spot spread, and number of hot spots.

Thermal Performance Exploration of Air Foil Shape of Pillars using Impinging Jet in Heat Sink

2021 ◽  
Vol 7 (5) ◽  
pp. 2794-2807
Author(s):  
Deepak Kumar ◽  
Mohammad Zunaid ◽  
Samsher Gautam
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Jet Impingement ◽  
Constant Heat Flux ◽  
Diameter Ratio ◽  
Heat Transfer Augmentation ◽  
The Heat Transfer Coefficient ◽  
Selection Of

Objectives: The current investigation introduces the concept of heat sink with combination of jet impingement, micro – channel and air foil shaped pillars. A numerical model is designed to explore the thermal performance of jet impingement with constant heat flux. The steady state conditions are assumed for the laminar and incompressible flow. For the purpose of study dimensionless variables are formed. The performance of jet impingement was predicted in terms of different parameters like temperature rise, drop in pressure and coefficient of heat transfer. Augmentation in pitch diameter ratio, leads to increase in temperature for a particular value of height diameter ratio. Also the heat transfer coefficient gets lowered with the increase in pitch diameter ratio. So proper selection of dimensionless parameters to increase the heat dissipation is of utmost importance.

scholarly journals Study of Mini Channel Heat Sink with Different Internal Configuration

2020 ◽  
Vol 319 ◽  
pp. 02004
Author(s):  
Muhammad Akif Rahman ◽  
Md Badrath Tamam ◽  
Md Sadman Faruque ◽  
A.K.M. Monjur Morshed
Keyword(s):  
Nusselt Number ◽  
Thermal Performance ◽  
Heat Sink ◽  
Rectangular Channel ◽  
Three Dimensional ◽  
Heat Sinks ◽  
Maximum Temperature ◽  
Rectangular Channels ◽  
Flow Through ◽  
Internal Configuration

In this paper a numerical analysis of three-dimensional laminar flow through rectangular channel heat sinks of different geometric configuration is presented and a comparison of thermal performance among the heat sinks is discussed. Liquid water was used as coolant in the aluminum made heat sink with a glass cover above it. The aspect ratio (section height to width) of rectangular channels of the mini-channel heat sink was 0.33. A heat flux of 20 W/cm2 was continuously applied at the bottom of the channel with different inlet velocity for Reynold’s number ranging from 150 to 1044. Interconnectors and obstacles at different positions and numbers inside the channel were introduced in order to enhance the thermal performance. These modifications cause secondary flow between the parallel channels and the obstacles disrupt the boundary layer formation of the flow inside the channel which leads to the increase in heat transfer rate. Finally, Nusselt number, overall thermal resistance and maximum temperature of the heat sink were calculated to compare the performances of the modified heat sinks with the conventional mini channel heat sink and it was observed that the heat sink with both interconnectors and obstacles enhanced the thermal performance more significantly than other configurations. A maximum of 36% increase in Nusselt number was observed (for Re =1044).

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.  

Thermal Performance of Micro-Jet Impingement Device With Parallel Flow, Jet-Adjacent Fluid Removal

2018 ◽  
Author(s):  
Todd M. Bandhauer ◽  
David R. Hobby ◽  
Chris Jacobsen ◽  
Dave Sherrer
Keyword(s):  
Reynolds Number ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Heated Surface ◽  
Jet Impingement ◽  
Impinging Jets ◽  
Thermal Interface Material ◽  
Cooling Device ◽  
Impingement Cooling ◽  
Jet Array

In a variety of electronic systems, cooling of various components imposes a significant challenge. A major aspect that inhibits the performance of many cooling solutions is the thermal resistance between the chip package and the cooling structure. Due to its low thermal conductivity, the thermal interface material (TIM) layer imposes a significant thermal resistance on the chip to cooling fluid thermal path. Advanced cooling methods that bypass the TIM have shown great potential in research and some specialty applications, yet have not been adopted widely by industry due to challenges associated with practical implementation and economic constraints. One advanced cooling method that can bypass the TIM is jet impingement. The impingement cooling device investigated in the current study is external to the integrated circuit (IC) package and could be easily retrofitted onto any existing microchip, similar to a standard heatsink. Jet impingement cooling has proven effective in previous studies. However, it has been shown that jet-to-jet interference severely degrades thermal performance of an impinging jet array. The present research addresses this challenge by utilizing a flow path geometry that allows for withdrawal of the impinging fluid immediately adjacent to each jet in the array. In this study, a jet impingement cooling solution for high-performance ICs was developed and tested. The cooling device was fabricated using modern advanced manufacturing techniques and consisted of an array of micro-scale impinging jets. A second array of fluid return paths was overlain across the jet array to allow for direct fluid extraction in the immediate vicinity of each jet, and fluid return passages were oriented in parallel to the impinging jets. The following key geometric parameters were utilized in the device: jet diameter (D = 300μm), distance from jet to impinging surface (H/D = 2.5), spacing between jets (S/D = 8), spacing between fluid returns (Sr/D = 8), diameter of fluid returns (Dr/D = 5). The device was mounted to a 2cm × 2cm uniformly heated surface which produced up to 165W and the resulting fluid-to-surface temperature difference was measured at a variety of flow rates. For this study, the device was tested using single-phase water. Jet Reynolds number ranged from 300–1500 and an average heat transfer coefficient of 13,100 W m−2 K−1 was achieved at a Reynolds number of only Red = 305.

Understanding the Impact of Flow Bypass on the Thermal Performance of Air Cooled Heat Sinks

2014 ◽  
Author(s):  
Krishna Kota ◽  
Mohamed M. Awad
Keyword(s):  
Energy Conservation ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Heat Sink ◽  
Heat Sinks ◽  
Laminar Regime ◽  
Flow Energy ◽  
Factor Α ◽  
The Impact ◽  
Fundamental Mass

In this effort, theoretical modeling was employed to understand the impact of flow bypass on the thermal performance of air cooled heat sinks. Fundamental mass and flow energy conservation equations across a longitudinal fin heat sink configuration and the bypass region were applied and a generic parameter, referred as the Flow Bypass Factor (α), was identified from the theoretical solution that mathematically captures the effect of flow bypass as a quantifiable parameter on the junction-to-ambient thermal resistance of the heat sink. From the results obtained, it was found that, at least in the laminar regime, the impact of flow bypass on performance can be neglected for cases when the bypass gap is typically less than 5% of the fin height, and is almost linear at high relative bypass gaps (i.e., usually for bypass gaps that are more than 10–15% of the fin height). It was also found that the heat sink thermal resistance is more sensitive to small bypass gaps and the effect of flow bypass decreases with increasing bypass gap.

Thermal Management of Low Profile Applications

2007 ◽  
Author(s):  
Ed Walsh ◽  
Pat Walsh ◽  
Ronan Grimes ◽  
Vanessa Egan
Keyword(s):  
Thermal Management ◽  
Thermal Performance ◽  
Heat Sink ◽  
Optimal Solution ◽  
Battery Life ◽  
Heat Conducting ◽  
Pumping Power ◽  
Low Profile ◽  
Thermal Solution ◽  
Footprint Area

There is an increasing need for low profile thermal management solutions for applications in the range of five to ten watts targeted at portable electronic devices. This need is emerging due to enhanced power dissipation levels in portable electronics. This work focuses upon the optimization of such a solution within certain constraints of profile and footprint area. A number of fan geometries have been investigated where both the inlet and exit rotor angles are varied relative to the heat conducting fins on a heat sink. The ratio of fan diameter to heat sink fin length was also varied. The objective was to determine the optimal solution from a thermal management perspective within defined constraints. The results show good thermal performance for low profile thermal management solutions, and highlight the need to develop the heat sink and fan as an integrated thermal solution rather than in isolation as is the traditional methodology. It is also found that while increasing pumping power generally improves the thermal performance, only small gains are achieved for relatively large pumping power increases. This is important in optimizing portable systems which are powered by limited battery life.

Experimental Investigation on Thermal Performance of Heat Sink With Two Pairs of Embedded Heat Pipes

2007 ◽  
Author(s):  
Hsiang-Sheng Huang ◽  
Jung-Chang Wang ◽  
Sih-Li Chen
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Heat Transfer Rate ◽  
Thermal Performance ◽  
Heat Sink ◽  
Transfer Rate ◽  
Heat Pipes ◽  
Total Heat ◽  
Heating Power ◽  
Total Heat Transfer

This article provides an experimental method to study the thermal performance of a heat sink with two pairs (outer and inner pair) of embedded heat pipes. The proposed method can determine the heat transfer rate of the heat pipes under various heating power of the heat source. A comprehensive thermal resistance network of the heat sink is also developed. The network estimates the thermal resistances of the heat sink by applying the thermal performance test result. The results show that the outer and inner pairs of heat pipes carries 21% and 27% of the total heat transfer rate respectively, while 52% of the heating power is dissipated from the base plate to the fins. The dominated thermal resistance of the heat sink is the base to heat pipes resistance which is strongly affected by the thermal performance of the heat pipes. The total thermal resistance of the heat sink shows the lowest value, 0.23°C/W, while the total heat transfer rate of the heat sink is 140W and the heat transfer rate of the outer and inner pairs of heat pipes is 30W and 38 W, respectively.

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