Air Cooling Study of Transient Natural Convection Heat Transfer From Simulated Electronic Chips

2004 ◽  
Author(s):  
H. Bhowmik ◽  
K. W. Tou
Keyword(s):  
Heat Transfer ◽  
Rectangular Channel ◽  
Convection Heat Transfer ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Air Cooling ◽  
Heat Sources ◽  
Heat Transfer Characteristics ◽  
Discrete Heat Sources ◽  
Transient Period

Experiments are performed to study the heat transfer characteristics during the power-on transient period from an array of 4 × 1 discrete heat sources in a vertical rectangular channel using air as the working fluid. The heat flux ranges from 1000 W/m2 to 5000 W/m2. For 2 mm protrusion of the heater, the effect of heat fluxes and chip numbers are investigated and observed that the transient Nul strongly depends on the number of chips. Correlations are presented for individual chips as well as for overall data in the transient regime.

Experimental Thermal Behavior of Electronic Chips in a Channel During Pump-On Transient Period

Volume 4 ◽  
2004 ◽  
Author(s):  
H. Bhowmik ◽  
K. W. Tou ◽  
C. P. Tso
Keyword(s):  
Rectangular Channel ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Heat Sources ◽  
Empirical Correlations ◽  
Heat Transfer Characteristics ◽  
Flux Flow ◽  
Flow Rates ◽  
Discrete Heat Sources ◽  
Transient Period

Experiments are performed to study the heat transfer characteristics during the pump-on transient period from an array of 4 × 1 flush mounted discrete heat sources in a vertical rectangular channel using water as the working fluid. The experimental data covers the flow regime with Reynolds number based on heat source length ranging from 1050 to 2625. The applied uniform heat fluxes to the chips are 1, 3, 5 and 7 W/cm2. The effects of heat flux, flow rates and chip numbers are investigated and empirical correlations are developed for investigated and empirical correlations are developed for individual chips as well as for overall data in the transient regime. The transient correlation recommended is Nul/(Pel)1/3 = 3.5(Fo)1/4.

An Experimental Study of Transient Heat Transfer From Discrete Heat Sources in Water Cooled Vertical Rectangular Channel

2004 ◽  
Vol 127 (3) ◽  
pp. 193-199 ◽  
Author(s):  
H. Bhowmik ◽  
K. W. Tou
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Source ◽  
Rectangular Channel ◽  
Convection Heat Transfer ◽  
Uniform Heat Flux ◽  
Heat Sources ◽  
Discrete Heat Sources ◽  
Wide Range ◽  
Transfer Behavior

Experiments are performed to study the single-phase transient forced convection heat transfer on an array of 4×1 flush-mounted discrete heat sources in a vertical rectangular channel during the pump-on transient operation. Water is the coolant media and the flow covers the wide range of laminar flow regime with Reynolds number, based on heat source length, from 800 to 2625. The applied uniform heat flux ranges from 1 to 7W∕cm2. For flush-mounted heaters the heat transfer characteristics are studied and correlations are presented for four chips as well as for overall data in the transient regime. The experimental results indicate that the heat transfer coefficient is affected strongly by the number of chips and the Reynolds number. Finally the general impacts of heat source protrusions (B=1, 2 mm) on heat transfer behavior of four chips are investigated by comparing the results obtained from flush-mounted (B=0) heaters.

Influence of Flow Acceleration on Convection Heat Transfer of CO2 at Supercritical Pressures and Air in a Vertical Micro Tube

2010 ◽  
Author(s):  
Pei-Xue Jiang ◽  
Rui-Na Xu ◽  
Zhi-Hui Li ◽  
Chen-Ru Zhao
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Wall Temperature ◽  
Convection Heat Transfer ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Convection Heat ◽  
Downward Flow ◽  
Flow Acceleration ◽  
Flow And Heat Transfer

The convection heat transfer of CO2 at supercritical pressures in a 0.0992 mm diameter vertical tube at relatively high Reynolds numbers (Rein = 6500), various heat fluxes and flow directions are investigated experimentally and numerically. The effects of buoyancy and flow acceleration resulting from the dramatic property variations are studied. The Results show that the local wall temperature varied non-linearly for both upward and downward flow when the heat flux was high. The difference in the local wall temperature between upward and downward flow is very small when the other test conditions are held the same, which indicates that for supercritical CO2 flowing in a micro tube as employed in this study, the buoyancy effect on the convection heat transfer is insignificant and the flow acceleration induced by the axial density variation with temperature is the main factor leading to the abnormal local wall temperature distribution at high heat fluxes. The predicted temperatures using the LB low Reynolds number turbulence model correspond well with the measured data. To further study the influence of flow acceleration on the convection heat transfer, air is also used as the working fluid to numerically investigate the fluid flow and heat transfer in the vertical micro tube. The results show that the effect of compressibility on the fluid flow and heat transfer of air in the vertical micro tube is significant but that the influence of thermal flow acceleration on convection heat transfer of air in a vertical micro tube is insignificant.

Forced Convection in a Porous Channel With Discrete Heat Sources

2000 ◽  
Vol 123 (2) ◽  
pp. 404-407 ◽  
Author(s):  
C. Cui ◽  
X. Y. Huang ◽  
C. Y. Liu
Keyword(s):  
Heat Transfer ◽  
Reynolds Numbers ◽  
Heat Fluxes ◽  
Experimental Results ◽  
Porous Channel ◽  
Heat Sources ◽  
Nusselt Numbers ◽  
Discrete Heat Sources ◽  
Flow Through ◽  
Good Agreement

An experimental study was conducted on the heat transfer characteristics of flow through a porous channel with discrete heat sources on the upper wall. The temperatures along the heated channel wall were measured with different heat fluxes and the local Nusselt numbers were calculated at the different Reynolds numbers. The temperature distribution of the fluid inside the channel was also measured at several points. The experimental results were compared with that predicted by an analytical model using the Green’s integral over the discrete sources, and a good agreement between the two was obtained. The experimental results confirmed that the heat transfer would be more significant at leading edges of the strip heaters and at higher Reynolds numbers.

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