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.

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.

Analyses of Convection Heat Transfer From Discrete Heat Sources in a Vertical Rectangular Channel

2004 ◽  
Vol 127 (3) ◽  
pp. 215-222 ◽  
Author(s):  
H. Bhowmik ◽  
C. P. Tso ◽  
K. W. Tou
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Rectangular Channel ◽  
Convection Heat Transfer ◽  
Working Fluid ◽  
Convection Heat ◽  
Empirical Correlations ◽  
Flux Flow ◽  
Wide Range

Steady-state experiments are performed to study the convection heat transfer from four in-line simulated chips in a vertical rectangular channel using water as the working fluid. The experimental data cover a wide range for laminar flow under natural, mixed, and forced convection conditions with the Reynolds number based on the channel hydraulic diameter ranging from 40 to 2220 and on the heat source length ranging from 50 to 2775. The heat flux ranges from 0.1W∕cm2to0.6W∕cm2. The effects of heat flux, flow rates, and chip number are investigated and results indicate that the Nusselt number is strongly affected by the Reynolds number. To develop empirical correlations, the appropriate value of the exponent n of ReD is determined to collapse all the lines into a single line to show the independence of heat flux. Based on experimental results, the empirical correlations are developed for relations using Nuℓ, ReD, and GrD. The results are compared to predictions from a three-dimensional numerical simulation, and a numerical correlation is also developed.

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.

Experimental Investigation of a Flexible Bellows Heat Pipe for Cooling Discrete Heat Sources

1990 ◽  
Vol 112 (3) ◽  
pp. 602-607 ◽  
Author(s):  
B. R. Babin ◽  
G. P. Peterson
Keyword(s):  
Heat Pipe ◽  
Computer Model ◽  
Heat Pipes ◽  
Heat Fluxes ◽  
Heat Sources ◽  
Discrete Heat Sources ◽  
Operational Characteristics ◽  
And Performance ◽  
Experimental Values ◽  
Operating Temperature Range

A computer model was developed to aid in the design of a flexible bellows heat pipe for cooling small discrete heat sources or arrays of small heat sources. This model was used to evaluate the operational characteristics and performance limitations of these heat pipes and to formulate and optimize a series of conceptual designs. Three flexible bellows heat pipes approximately 40 mm in length and 6 mm in diameter were constructed and tested using three different wick configurations. The test pipes were found to be boiling limited over most of the operating temperature range tested. Heat fluxes in excess of 200 W/cm2 were obtained and thermal resistance values of less than 0.7 °C/W were measured. Although the computer model slightly underestimated the experimentally determined transport limit for one of the wicking configurations, the remaining transport predictions were consistently within 8 percent of the experimental values.

Effects of Working Fluid, Fill Ratio and Orientation on Looped and Unlooped Pulsating Heat Pipes

2005 ◽  
Author(s):  
Kathryn Nikkanen ◽  
Christian G. Lu ◽  
Masahiro Kawaji
Keyword(s):  
Heat Pipe ◽  
Rectangular Channel ◽  
Heat Pipes ◽  
High Heat ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Fill Ratio ◽  
Triangular Channel ◽  
Horizontal Orientation

Improved miniaturization and a trend towards increasingly dense and compact architectures have led to unmanageably high heat fluxes in electronic components. In order to keep temperatures at operational levels more advanced cooling solutions are being required that go beyond the solid heat sink and forced convection. Pulsating heat pipes made out of multi port extrusion tubing are a proposed solution. Typically, gas-liquid slug flow occurs in the serpentine channel imbedded in the pulsating heat pipe. Vapour is produced in the heated section and condensed in the cooled section located at opposite ends of the heat pipe. In this work, experiments were conducted on four Multi-Port Extruded (MPE) aluminum tubing heat pipes with different internal structures: rectangular channel looped, rectangular channel unlooped, triangular channel looped, and triangular channel unlooped. The effect of changing the working fluid (ethanol or de-ionized water), fill ratio, and orientation were measured and compared for the different heat pipes. It was found that most of the heat pipes performed better with ethanol than de-ionized water. Only the looped rectangular channel heat pipe performed satisfactorily with de-ionized water, which is attributed both to the larger channel size and the looped architecture. The unlooped heat pipes performed best at the lowest fill ratios (10%) while the looped heat pipes showed their best performances between 30 and 50% with marked decrease at the lower and higher fill ratios. Both looped heat pipes performed poorly in horizontal orientation as compared to vertical, however, the unlooped heat pipes performed quite well in both orientations. This may be more the effect of the fill ratio on horizontal performance as literature suggests that horizontal orientation requires a lower fill ratio to perform satisfactorily.

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.

scholarly journals Effect of working fluids and internal diameters on thermal performance of vertical and horizontal closed-loop pulsating heat pipes with multiple heat sources

2016 ◽  
Vol 20 (1) ◽  
pp. 77-87 ◽  
Author(s):  
Niti Kammuang-Lue ◽  
Phrut Sakulchangsatjatai ◽  
Pradit Terdtoon
Keyword(s):  
Thermal Performance ◽  
Closed Loop ◽  
Capillary Tube ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Internal Diameter ◽  
Heat Sources ◽  
Pulsating Heat Pipe ◽  
Working Fluids ◽  
Fundamental Information

Some electrical applications have a number of heat sources. The closed-loop pulsating heat pipe (CLPHP) is applied to transfer heat from these devices. Since the CLPHP primarily transfers heat by means of the working fluid?s phase change in a capillary tube, the thermal performance of the CLPHP significantly depends on the working fluid type and the tube?s internal diameter. In order to provide the fundamental information for manufacturers of heat exchangers, this study on the effect of working fluids and internal diameters has been conducted. Three electrical plate heaters were installed on the CLPHP as the heat sources. The experiments were conducted by varying the working fluid to be R123, ethanol, and water, and the internal diameter to be 1.0 mm, 1.5 mm, and 2.0 mm. For each set of the same working fluid and internal diameter, the input heat fluxes of the heat sources were also made to vary within six different patterns. It can be concluded that when the latent heat of evaporation increases - in the case of vertical CLPHP - and when the dynamic viscosity of the liquid increases - in the case of horizontal CLPHP - the thermal performance decreases. Moreover, when the internal diameter increases, the thermal performance increases for both of vertical and horizontal CLPHPs.

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