scholarly journals Thermal Analysis of Semi-Circular Pin Fins for Application in Electronics Cooling

2019 ◽  
Vol 8 (2) ◽  
pp. 2366-2374
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Surface Area ◽  
Pressure Coefficient ◽  
Electronics Cooling ◽  
Thermal Conditions ◽  
Base Plate ◽  
Working Fluid ◽  
Power Sources ◽  
Pin Fins

Efficient thermal energy management of a system is always a prime requirement for many equipment and industries. The performance of almost all devices are affected by the thermal conditions of the system, which also include the surroundings. Generation of heat is an unavoidable phenomenon for any device that runs on external power sources. The generated heat in such systems must be dissipated to the surrounding. It requires efficient utilization of the surface area with minimum flow losses in the system. It was always desirable to have a heat sink in the all devices that occupy minimum space with maximum effectiveness. The present work is an effort to analyze conjugate heat transfer physics in a 3-D system of aluminum pin fins, with air as the working fluid. A finite element solver, COMSOL 4.3a has been used in simulating a staggered pin fin arrangements placed over a base plate. The solver is validated using the empirical data of previous literature. The thermal analysis has been performed on semicircular pin fins with uniform cross section. Consideration is given to staggered arrangement of semicircular fins with various relative distances between two sections of a circle with various inlet velocities. Heat transfer coefficient, Nusselt number, skin friction coefficient and pressure coefficient are four parameters that are taken into consideration for analyzing all the fin geometries in the current study. The proposed shapes are designed to increase the wetted surface area by keeping the fin material volume constant

Reciprocating-Mechanism Driven Heat Loops and Their Applications

2003 ◽  
Author(s):  
Yiding Cao ◽  
Mingcong Gao
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Electronics Cooling ◽  
Working Fluid ◽  
High Heat Flux ◽  
Two Phase ◽  
Condenser Section ◽  
Evaporator Section ◽  
Two Phase Heat Transfer ◽  
Transfer Device

This paper introduces a novel heat transfer mechanism that facilitates two-phase heat transfer while eliminating the so-called cavitation problem commonly encountered by a conventional pump. The heat transfer device is coined as the reciprocating-mechanism driven heat loop (RMDHL), which includes a hollow loop having an interior flow passage, an amount of working fluid filled within the loop, and a reciprocating driver. The hollow loop has an evaporator section, a condenser section, and a liquid reservoir. The reciprocating driver is integrated with the liquid reservoir and facilitates a reciprocating flow of the working fluid within the loop, so that liquid is supplied from the condenser section to the evaporator section under a substantially saturated condition and the so-called cavitation problem associated with a conventional pump is avoided. The reciprocating driver could be a solenoid-operated reciprocating driver for electronics cooling applications and a bellows-type reciprocating driver for high-temperature applications. Experimental study has been undertaken for a solenoid-operated heat loop in connection with high heat flux thermal management applications. Experimental results show that the heat loop worked very effectively and a heat flux as high as 300 W/cm2 in the evaporator section could be handled. The applications of the bellows-type reciprocating heat loop for gas turbine nozzle guide vanes and the leading edges of hypersonic vehicles are also illustrated. The new heat transfer device is expected to advance the current two-phase heat transfer device and open up a new frontier for further research and development.

Experimental Investigation of Enhanced Two-Phase Evaporator Using Aluminum Foams

2015 ◽  
Author(s):  
Francesco Agostini ◽  
Waylon Puckett ◽  
Ryan Nelson ◽  
Daniele Torresin ◽  
Bruno Agostini ◽  
...  
Keyword(s):  
Aluminum Foam ◽  
Metal Foam ◽  
Electronics Cooling ◽  
Base Plate ◽  
Heat Fluxes ◽  
Experimental Results ◽  
Working Fluid ◽  
Vapor Flow ◽  
Base Temperature ◽  
Two Phase

A novel two-phase thermosyphon with a metal foam based evaporator is presented as a solution for the cooling of power-electronic semiconductor modules. A horizontal evaporator configuration is investigated: the evaporator consists of an aluminum chamber, with aluminum foam brazed to the base plate in three different configurations. One of the configurations has an open vapor chamber above the foam, another has foam filling the entire evaporator chamber, and the third has bores drilled in the foam parallel to the base plate from inlet to outlet along the direction of the vapor flow. The aluminum foam has a porosity of 95%, and a pore density of 20 PPI (pores per inch). A liquid distribution and a vapor collector chamber are respectively present at the entrance and at the exit of the evaporator. The power modules are attached on the evaporator body that collects the heat generated during the operation of the semiconductor devices. A vapor riser guides the vapor to a finned-tube air-cooled heat exchanger. A liquid downcomer from the condenser constantly feeds the evaporator channels. The system works with gravity-driven circulation only. The described system was designed and tested with an extensive experimental campaign. The evaporators were tested for power losses ranging between 500 and 3000 W, corresponding to applied heat fluxes between 3 and 20 W/cm2. The experimental results will be presented for inlet air at ambient temperature of 20°C with volumetric flow rates between 100 and 680 m3/h. The working fluid was refrigerant R245fa. The fluid filling effect was investigated. For each evaporator the results will be presented in terms of maximum thermal resistance and cooler base temperature. The base temperature distribution between different evaporators will also be presented and discussed being an important design parameter in power electronics cooling. Thermal resistances were measured between 15 and 30 K/kW. The experimental results indicated a promising conclusion favoring the implementation of aluminum foam evaporators for enhancement of heat transfer during pool boiling.

Chaotic Mixing: A Sure Way for Optimal Thermal Conditions?

2010 ◽  
Author(s):  
M. F. M. Speetjens
Keyword(s):  
Heat Transfer ◽  
Thermal State ◽  
Electronics Cooling ◽  
Thermal Conditions ◽  
Laminar Flows ◽  
Chaotic Mixing ◽  
Asymptotic State ◽  
Driven Cavity ◽  
Time Periodic

Chaotic fluid mixing is generally considered to enhance fluid-wall heat transfer and thermal homogenisation in laminar flows. However, this essentially concerns the transient stage towards a fully-developed (thermally-homogeneous) asymptotic state and then specifically for high Pe´clet numbers Pe (convective heat transfer dominates). The role of chaos in the asymptotic state at lower Pe, relevant to continuously-operating compact devices as, for instance, micro-electronics cooling systems, remains largely unexplored to date. The present study seeks to gain first insight into this matter by the analysis of a representative model problem: heat transfer in the 2D time-periodic lid-driven cavity flow induced via non-adiabatic walls. The asymptotic time-periodic thermal state is investigated in terms of both the temperature field and the thermal transport routes. This combined Eulerian-Lagrangian approach enables fundamental investigation of the connection between heat transfer and chaotic mixing and its ramifications for temperature distributions and heat-transfer rates. The analysis exposes a very different role of chaos in that its effectiveness for thermal homogenisation and heat-transfer enhancement is in low-Pe asymptotic states marginal at best. Here chaos may in fact locally amplify temperature fluctuations and thus hamper instead of promote thermal homogeneity. These findings reveal that optimal thermal conditions are not always automatic with chaotic mixing and may depend on a more delicate interplay between flow and heat-transfer mechanisms.

Thermal Analysis for Heat Transfer Enhancement in Perforated Pin Fins of Various Shapes with Staggered Arrays

2018 ◽  
Vol 40 (3-4) ◽  
pp. 295-319 ◽  
Author(s):  
Ambarish Maji ◽  
Dipankar Bhanja ◽  
Promod Kumar Patowari ◽  
Balaram Kundu
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Heat Transfer Enhancement ◽  
Transfer Enhancement ◽  
Pin Fins

Thermal Performance of Metal Foam Heat Sink With Pin Fins for Nonuniform Heat Flux Electronics Cooling

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Yongtong Li ◽  
Liang Gong ◽  
Minghai Xu ◽  
Yogendra Joshi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Metal Foam ◽  
Electronics Cooling ◽  
Flow Distribution ◽  
Junction Temperature ◽  
Transfer Performance ◽  
Pin Fins

Abstract In this paper, a concept of metal foam heat sink with pin fins (MFPF heat sink) is proposed to improve the cooling performance of high-powered electronics with nonuniform heat flux. Numerical simulations are carried out to investigate the thermohydraulic performance of MFPF heat sink, and the metal foam (MF) heat sink and traditional pin fin (PF) heat sink are employed for comparison. The capability of MFPF heat sink in handling nonuniform heat flux is examined under different power levels. It indicates that the MFPF heat sink greatly enhances the heat transfer performance, due to the common effects of the improved flow distribution and enhanced overall effective thermal conductivity (ETC). Results also show that the MFPF heat sink promotes the improvement of the bottom wall temperature uniformity. Porosity has more pronounced effects on heat transfer performance of MFPF heat sink than pore density. A nonuniform distribution heat flux (15–80–15 W/cm2) can be successfully dissipated using the proposed MFPF heat sink with the junction temperature below 95 °C at Re of 500.

A Novel Concept to Improve the Performance of LED Panel Using Drilled Holes

2005 ◽  
Author(s):  
S. B. Chiang ◽  
C. C. Wang
Keyword(s):  
Heat Transfer ◽  
Surface Area ◽  
Heat Sink ◽  
Maximum Temperature ◽  
Transfer Coefficients ◽  
Pin Fin ◽  
Heat Transfer Coefficients ◽  
Pin Fins ◽  
Overall Performance ◽  
Novel Concept

In this study, the concept of the thermal module of LEDs cooling by use of drilled hole to entrain air flow was examined. It is found that the drilled hole does not necessarily improve the overall performance. It depends on the size of the drilled hole, the number of drilled holes, and the locations. The heat transfer coefficients are generally increased with the number of drilled holes and the diameter of the drilled hole. In this paper, the plate fin heat sink has a higher heat transfer coefficients than pin fins, but the overall performance of the LED panel having pin fin outperforms that of plate fin. This is because the pin fin provides much larger surface area. For decrease the maximum temperature of the LED panel, placement of the drilled holes along the hot region will be more effective.

Experimental Investigation of Area Ratio on Microjet Array Heat Transfer

2009 ◽  
Author(s):  
Gregory J. Michna ◽  
Eric A. Browne ◽  
Yoav Peles ◽  
Michael K. Jensen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Electronics Cooling ◽  
Jet Impingement ◽  
Area Ratio ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Transfer Performance ◽  
Transfer Coefficients ◽  
High Heat Transfer

Electronics cooling is becoming increasingly difficult due to increasing power consumption and decreasing size of processor chips. Heat fluxes in processors and power electronics are quickly approaching levels that cannot be easily addressed by forced air convection over finned heat sinks. Jet impingement cooling offers high heat transfer coefficients and has been used effectively in conventional-scale applications such as turbine blade cooling and the quenching of metals. However, literature in the area of microjet arrays is scarce and has not studied arrays of large area ratios. Hence, the objective of this study is to experimentally assess the heat transfer performance of arrays of microjets. The microjet arrays were fabricated using MEMS processes in a clean room environment. The heat transfer performance of several arrays using deionized water as the working fluid was investigated. Inline and staggered array arrangements were investigated, and the area ratio (total area of the jets divided by the surface area) was varied between 0.036 and 0.35. Reynolds numbers defined by the jet diameter were in the range of 50 to 3,500. Heat fluxes greater than 1,000 W/cm2 were obtained at fluid inlet-to-surface temperature differences of less than 30 °C. Heat transfer performance improved as the area ratio was increased.

Effect of Nanoparticle Coating on the Performance of a Miniature Loop Heat Pipe for Electronics Cooling Applications

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Trijo Tharayil ◽  
Lazarus Godson Asirvatham ◽  
S. Rajesh ◽  
Somchai Wongwises
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Physical Vapor Deposition ◽  
Low Voltage ◽  
Circuit Breaker ◽  
Electronics Cooling ◽  
Working Fluid ◽  
Loop Heat Pipe ◽  
Transfer Coefficients ◽  
Nanoparticle Coating

The effect of nanoparticle coating on the performance of a miniature loop heat pipe (mLHP) is experimentally investigated for heat inputs of 20–380 W using distilled water as the working fluid. Applications include the cooling of electronic devices such as circuit breaker in low voltage switch board and insulated gate bipolar transistor. Physical vapor deposition method is used to coat the nanoparticles on the evaporator surface for different coating thicknesses of 100 nm, 200 nm, 300 nm, 400 nm, and 500 nm, respectively. An optimum filling ratio (FR) of 30% is chosen for the analysis. Experimental findings show that the nanoparticle coating gives a remarkable improvement in heat transfer of the heat pipe. An average reduction of 6.7%, 11.9%, 17.2%, and 22.6% in thermal resistance is observed with coating thicknesses of 100 nm, 200 nm, 300 nm, and 400 nm, respectively. Similarly, enhancements in evaporator heat transfer coefficients of 47%, 63.5%, 73.5%, and 86% are noted for the same coating thicknesses, respectively. Evaporator wall temperature decreased by 15.4 °C for 380 W with a coating thickness of 400 nm. The repeatability test ensures the repeatability of experiments and the stability of coatings in the long run.

Investigation of Heat Transfer in Evaporator of Microchannel Loop Heat Pipe

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Alexander A. Yakomaskin ◽  
Valery N. Afanasiev ◽  
Nikolay N. Zubkov ◽  
Dmitry N. Morskoy
Keyword(s):  
Heat Transfer ◽  
Electronics Cooling ◽  
Open Loop ◽  
Main Element ◽  
Working Fluid ◽  
Vapor Flow ◽  
Loop Heat Pipes ◽  
Evaporation And Condensation ◽  
Flow Geometry ◽  
Compensation Chamber

Loop heat pipes (LHP) are heat transfer devices which use evaporation and condensation of working fluid to transfer heat and use capillary forces to provide fluid circulation in a closed loop. One of the main applications of LHP is cooling of electronic components. Further development of this field is associated with miniaturization. Thus, there are strict limits imposed upon size of elements of heat transfer devices in electronics cooling. One of such elements is an evaporator of the LHP, its main element. This paper deals with the LHP evaporator and is aimed at showing dependence of wick conductivity, thickness, and vapor flow geometry on overall heat transfer performance. An open loop experimental setup was created. Experiments were carried out with various configurations. The evaporator consisted of a microchannel (MC) plate, with groove widths of 100 and 300 μm, wick (metal and nonmetal porous materials were used) and a compensation chamber (CC). Heat load varied from 20 to 140 W in steps of 20 W. The area of the heater was equal to 19 × 19 mm2. The working fluid is de-ionized water. Experimental results include data on temperature distribution across the wick's height, temperature of microchannel's surface, and temperature of water in the compensation chamber. The results reveal a potential for performing optimization of the zone of evaporation in order to produce thinner LHP evaporators.

The Effect of Chaotic Mixing on Heat Transfer in Continuous Thermal Processes at Low Peclet Numbers

2010 ◽  
Author(s):  
M. F. M. Speetjens
Keyword(s):  
Heat Transfer ◽  
Electronics Cooling ◽  
Thermal Conditions ◽  
Laminar Flows ◽  
Chaotic Mixing ◽  
Asymptotic State ◽  
Thermal Processes ◽  
Driven Cavity ◽  
Transfer Rates

Chaotic fluid mixing is generally considered to enhance fluid-wall heat transfer and thermal homogenisation in laminar flows. However, this essentially concerns the transient stage towards a fully-developed (thermally-homogeneous) asymptotic state and then specifically for high Pe´clet numbers numbers Pe (convective heat transfer dominates). The role of chaos at lower Pe under both transient and asymptotic conditions, relevant to continuous thermal processes as e.g. micro-electronics cooling, remains largely unexplored to date. The present study seeks to gain first insight into this matter by the analysis of a representative model problem: heat transfer in the 2D time-periodic lid-driven cavity flow induced via non-adiabatic walls. Transient and asymptotic states are investigated in terms of both the temperature field and the thermal transport routes. This combined Eulerian-Lagrangian approach enables fundamental investigation of the connection between heat transfer and chaotic mixing and its ramifications for temperature distributions and heat-transfer rates. The analysis exposes a very different role of chaos in that its effectiveness for thermal homogenisation and heat-transfer enhancement is in low-Pe transient and asymptotic states marginal at best. Here chaos may in fact locally amplify temperature fluctuations and thus hamper instead of promote thermal homogeneity. These findings reveal that optimal thermal conditions are at lower Pe not automatic with chaotic mixing and may depend on a delicate interplay between flow and heat-transfer mechanisms.

Sign in / Sign up

Export Citation Format

Share Document