Thermal Performance Measurement for Confined Heat Sinks by Using a Modified Transient Liquid Crystal Technique

Author(s):  
S. T. Kuo ◽  
M. P. Wang ◽  
M. C. Wu ◽  
Y. H. Hung

A series of experimental investigations with a new modified transient liquid crystal method on the studies related to the fluid flow and heat transfer characteristics in a channel installed with a heat sink have been successfully performed. The parametric studies on the local and average effective heat transfer characteristics for confined heat sinks have been explored. The influencing parameters and conditions include air preheating temperature at channel inlet, flow velocity and heat sink types. Besides, a concept of the amount of enhanced heat transfer (AEHT) is introduced and defined as the ratio of j/f. The j/f ratio is almost independent of Reynolds number for a specific confined heat sink. The j/f ratios are 0.0603 and 0.0124 for fully-confined and unconfined heat sinks, respectively.

2005 ◽  
Vol 127 (4) ◽  
pp. 474-482 ◽  
Author(s):  
Ming-Chang Wu ◽  
Tiao-Yuan Wu ◽  
Sheng-Tzung Kuo ◽  
Meng-Ping Wang ◽  
Ying-Huei Hung

A series of experimental investigations with a new modified transient liquid crystal method on the studies related to the fluid flow and heat transfer characteristics in a channel installed with a heat sink have been successfully performed. The parametric studies on the local and average effective heat transfer characteristics for confined heat sinks have been explored. The influencing parameters and conditions include air preheating temperature at channel inlet, flow velocity and heat sink types. Besides, a concept of the amount of enhanced heat transfer (AEHT) is introduced and defined as the ratio of j∕f. The j∕f ratio is almost independent of Reynolds number for a specific confined heat sink. The j∕f ratios are 0.0603 and 0.0124 for fully-confined and unconfined heat sinks, respectively.


Author(s):  
Chan Byon ◽  
Sung Jin Kim

In this paper, a compact modeling method for predicting the thermal characteristics of vertical plate fin heat sinks under natural convection is presented. The plate fin heat sink is modeled using the volume-averaging approach. The solutions for velocity and temperature distributions are obtained by solving the averaged governing equations. In order to validate the model proposed in this paper, experimental investigations are performed. The resulting effective heat transfer coefficients of heat sinks are compared with those obtained through the compact modeling. Under comparison, the analytical solutions based on the compact modeling are shown to predict the heat transfer characteristics of plate fin heat sink quite well. Comparisons with other studies are also conducted. Using the validated model, the thermal resistances of heat sinks are obtained. The heat transfer characteristics of the heat sink under natural convection are compared with those of the heat sink subjected to forced convection. And finally, thermal optimization of heat sink is performed.


Author(s):  
Duckjong Kim ◽  
Sung Jin Kim

In the present work, a novel compact modeling method based on the volume-averaging technique and its application to the analysis of fluid flow and heat transfer in pin fin heat sinks are presented. The pin fin heat sink is modeled as a porous medium. The volume-averaged momentum and energy equations for fluid flow and heat transfer in pin fin heat sinks are obtained using the local volume-averaging method. The permeability, the Ergun constant and the interstitial heat transfer coefficient required to solve these equations are determined experimentally. To validate the compact model proposed in this paper, 20 aluminum pin fin heat sinks having a 101.43 mm × 101.43 mm base size are tested with an inlet velocity ranging from 1 m/s to 5 m/s. In the experimental investigation, the heat sink is heated uniformly at the bottom. Pressure drop and heat transfer characteristics of pin fin heat sinks obtained from the porous medium approach are compared with experimental results. Upon comparison, the porous medium approach is shown to predict accurately the pressure drop and heat transfer characteristics of pin fin heat sinks. Finally, surface porosities of the pin fin heat sink for which the thermal resistance of the heat sink is minimal are obtained under constraints on pumping power and heat sink size. The optimized pin fin heat sinks are shown to be superior to the optimized straight fin heat sinks in thermal performance by about 50% under the same constraints on pumping power and heat sink size.


1993 ◽  
Vol 13 (Supplement1) ◽  
pp. 195-198
Author(s):  
K. MINAKAMI ◽  
S. MOCHIZUKI ◽  
A. MURATA ◽  
Y. YAGI ◽  
H. IWASAKI

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