On heated surface transport of heat bearing thermal radiation and MHD Cross flow with effects of nonuniform heat sink/source and buoyancy opposing/assisting flow

Heat Transfer ◽  
2021 ◽  
Author(s):  
Assad Ayub ◽  
Hafiz A. Wahab ◽  
Syed Zahir Hussain Shah ◽  
Syed Latif Shah ◽  
Zulqurnain Sabir ◽  
...  
Keyword(s):  
Thermal Radiation ◽  
Heat Sink ◽  
Heated Surface ◽  
Cross Flow ◽  
Surface Transport

An Analytical Study of the Optimized Performance of an Impingement Heat Sink

2004 ◽  
Vol 126 (4) ◽  
pp. 528-534 ◽  
Author(s):  
S. B. Sathe ◽  
B. G. Sammakia
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Sink ◽  
High Performance ◽  
Cross Flow ◽  
High Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer ◽  
Flow Through

The results of a study of a new and unique high-performance air-cooled impingement heat sink are presented. An extensive numerical investigation of the heat sink performance is conducted and is verified by experimental data. The study is relevant to cooling of high-power chips and modules in air-cooled environments and applies to workstations or mainframes. In the study, a rectangular jet impinges on a set of parallel fins and then turns into cross flow. The effects of the fin thickness, gap nozzle width and fin shape on the heat transfer and pressure drop are investigated. It is found that pressure drop is reduced by cutting the fins in the central impingement zone without sacrificing the heat transfer due to a reduction in the extent of the stagnant zone. A combination of fin thicknesses of the order of 0.5 mm and channel gaps of 0.8 mm with appropriate central cutout yielded heat transfer coefficients over 1500 W/m2 K at a pressure drop of less than 100 N/m2, as is typically available in high-end workstations. A detailed study of flow-through heat sinks subject to the same constraints as the impingement heat sink showed that the flow-through heat sink could not achieve the high heat transfer coefficients at a low pressure drop.

Two-Phase Electronic Cooling Using Mini-Channel and Micro-Channel Heat Sinks: Part 1—Design Criteria and Heat Diffusion Constraints

1994 ◽  
Vol 116 (4) ◽  
pp. 290-297 ◽  
Author(s):  
Morris B. Bowers ◽  
Issam Mudawar
Keyword(s):  
Heat Flux ◽  
Heat Sink ◽  
Structural Integrity ◽  
Flow Boiling ◽  
Heated Surface ◽  
Heat Sinks ◽  
Heat Diffusion ◽  
High Heat Flux ◽  
Micro Channel ◽  
Channel Diameter

Mini-channel (D = 2.54 mm) and micro-channel (D = 510 μm) heat sinks with a 1-cm2 heated surface were tested for their high heat flux performance with flow boiling of R-113. Experimental results yielded CHF values in excess of 200 W cm−2 for flow rates less than 95 ml min−1 (0.025 gpm) over a range of inlet subcooling from 10 to 32°C. Heat diffusion within the heat sink was analyzed to ascertain the optimum heat sink geometry in terms of channel spacing and overall thickness. A heat sink thickness to channel diameter ratio of 1.2 provided a good compromise between minimizing overall thermal resistance and structural integrity. A ratio of channel pitch to diameter of less than two produced negligible surface temperature gradients even with a surface heat flux of 200 W cm−2. To further aid in determining channel diameter for a specific cooling application, a pressure drop model was developed, which is presented in the second part of the study.

scholarly journals NUMERICAL ANALYSIS OF TRAPEZOIDAL SHAPE DOUBLE LAYER MICROCHANNEL HEAT SINK

2014 ◽  
pp. 219-224
Author(s):  
DEEWAKAR SHARMA ◽  
PARBAR PRATHAM SINGH ◽  
HARRY GARG
Keyword(s):  
Comparative Study ◽  
Double Layer ◽  
Heat Sink ◽  
Minimum Temperature ◽  
Heated Surface ◽  
Maximum Temperature ◽  
Microchannel Heat Sink ◽  
Flow Area ◽  
Temperature Variations ◽  
Trapezoidal Shape

With increasing demand for higher computational speed and emerging micro-systems, thermal management poses serious challenge for efficient cooling. Among these liquid cooling using microchannels has gained significant attention and has been extended to its double layer configuration which eliminates the drawback of significant temperature variations in single layer system. The double layer configuration has been primarily analyzed for rectangular ducts. In this study the performance of trapezoidal shape double layer microchannel heat sink is investigated and compared to rectangular double layer heat sink of same flow area. Four different possible configurations are analyzed and comparative study among respective counter and parallel configuration is performed followed by comparison among each configuration. The performance is evaluated on the basis of maximum temperature attained at the heated surface as well as minimum temperature variations. Finally the best performing configuration is compared with double layer rectangular heat sink. Analysis shows that among various trapezoidal configurations, the one with larger side face to face is most suitable. Further comparative study with rectangular system shows that performance of trapezoidal double layer heat sink is superior in both aspects, i.e. minimum thermal resistance as well as minimum temperature variations.

scholarly journals Numerical Analysis of Cu + Al 2 O 3 / H 2 O Hybrid Nanofluid of Streamwise and Cross Flow with Thermal Radiation Effect: Duality and Stability

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Sumera Dero ◽  
Liaquat Ali Lund ◽  
Zahir Shah ◽  
Ebenezer Bonyah ◽  
Wejdan Deebani
Keyword(s):  
Differential Equations ◽  
Thermal Radiation ◽  
Radiation Effect ◽  
Nonlinear Partial Differential Equations ◽  
Upper And Lower Solutions ◽  
Temporal Stability ◽  
Cross Flow ◽  
Hybrid Nanofluid ◽  
Thermal Layer ◽  
Thermal Radiation Effect

The motion of water conveying copper and aluminum nanoparticles on a heated moving sheet when thermal radiation and stretching/shrinking surface is significant and is investigated in this study to announce the increasing effects of volume fractions, thermal radiation, and moving parameters on this transport phenomenon. Furthermore, the flow of a Cu − Al 2 O 3 /water hybrid nanofluid across a heated moving sheet has been studied in both cross and streamwise directions. Thermal radiation effect is also considered, as this effect along with cross flow has not yet been investigated for the hybrid nanofluid in the published literature. Two distinct types of nanoparticles, namely, Al 2 O 3 (alumina) and Cu (copper), have been used to prepare hybrid nanofluid where water is considered as a base fluid. The system of nonlinear partial differential equations (PDEs) has been transferred to ordinary differential equations (ODEs) by compatible transformations before solving them by employing the III-stage Lobatto-IIIa method in bvp4c solver in MATLAB 2017 software. Temporal stability analysis has been carried out in order to verify stable branch between two branches by obtaining the smallest eigenvalue values. The branches obtained are addressed in depth against every applied parameter using figures and tables. The results show that there are three ranges of branches, no solution exists when λ > λ c , dual branches exist when 0.23 ≤ λ ≤ λ c , and a single solution exists when λ > 0.23 . Moreover, thermal layer thickness declines initially and then enhances in the upper and lower solutions for the higher values of the thermal radiation parameter.

Development of a Hybrid Heat Sink for Thermal Management of Photovoltaic Cells

2019 ◽  
Author(s):  
Danish Rahman ◽  
Ahmad Almomani ◽  
Ibrahim Hassan ◽  
Yasser Al-Hamidi ◽  
Aziz Rahman
Keyword(s):  
Thermal Management ◽  
Heat Sink ◽  
Test Section ◽  
Bubbly Flow ◽  
Plug Flow ◽  
Cross Flow ◽  
Jet Impingement ◽  
Photovoltaic Cell ◽  
Bubble Sizes ◽  
Water Mass Flow Rate

Abstract The objective of this paper is to study the effect of multiple jet impingements on one another in a heat sink under adiabatic conditions. The jet impingement is a unique design which aimed to optimize the cooling performance of a concentrated photovoltaic cell. The paper is based on the design and fabrication of a new 9-celled test section. Initially, to set a baseline, individual cells in the 9-celled test section were tested alone in order to observe their flow regimes. These tests were completed by applying varying water cross flow rates to a set air-water mass flow rate exiting the jet impingement. Afterwards, two cells were tested in conjunction with one another under similar conditions. The location of the cells tested had been varied in order to observe how different cells interact with another. Plug flow and bubbly flow were consistently found through the various experiments. In general, it was noticed at higher crossflow rates the bubble sizes and quantity would decrease drastically.

Performance Investigation on Porous Micro Heat Sink for Cooling of High Power LEDs

2011 ◽  
Vol 204-210 ◽  
pp. 1481-1484
Author(s):  
Zhong Min Wan ◽  
Zheng Kai Tu ◽  
Jing Liu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Power ◽  
Heat Sink ◽  
Heated Surface ◽  
High Heat ◽  
Heat Fluxes ◽  
Local Thermal Equilibrium ◽  
Micro Pump

A novel porous micro heat sink system is presented for thermal management of high power LEDs, which has high heat transport capability. Numerical model for the micro heat sink is developed to describe liquid flow and heat transfer based on the local thermal equilibrium of porous media, and it is solved with SIMPLE algorithm. The numerical results show that the heated surface temperature of porous micro heat sink is low at high heat fluxes and is much less than the bearable temperature level of LED chips. The heat transfer coefficient of heat sink is very high, and increasing the liquid velocity can enhance the average heat transfer coefficient. The overall pressure loss of heat sink system increases with the increasing the inlet velocity, but the overall pressure drop is much less than the pumping pressure provided by micro pump.

An Experimental and Computational Sensitivity Analysis of Synthetic Jet Cooling Performance

2006 ◽  
Author(s):  
Yogen Utturkar ◽  
Mehmet Arik ◽  
Mustafa Gursoy
Keyword(s):  
Numerical Models ◽  
Heated Surface ◽  
Cross Flow ◽  
Heat Removal ◽  
Jet Impingement ◽  
Synthetic Jet ◽  
Thermal Source ◽  
Cooling Performance ◽  
Jet Cooling ◽  
The Impact

Synthetic jets are meso or micro scale fluidic devices, which operate on the "zero-net-mass-flux" principle. However, they impart a positive net momentum flux to the external environment, and are able to produce the cooling effect of a fan sans its ducting, reliability issues, and oversized dimensions. The rate of heat removal from the thermal source is expected to depend on the location, orientation, strength, and shape of the jet. In the current study, we investigate the impact of jet location and orientation on the cooling performance via time-dependent numerical simulations, and verify the same with experimental results. We firstly present the experimental study along with the findings. Secondly, we present the numerical models/results, which are compared with the experiments to gain the confidence in the computational methodology. Finally, a sensitivity evaluation has been performed by altering the position and alignment of the jet with respect to the heated surface. Two prime orientations of the jet have been considered, namely, perpendicular and cross jet impingement on the heater. It is found that if jet is placed at an optimum location in either impingement or cross flow position, it can provide similar enhancement.

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