Hideo Yoshino a , Motoo Fujii b, Xing Zhang b, Takuji Takeuchi a, and Souichi Toyomasu a# y5 ]/ `# S% c3 V% G
a) Fujitsu Kyushu System Engineering Limited, Fukuoka 814-8589, Japan7 R1 W5 o! n% ]+ ~4 Y" Y9 E- a# Q
b) Institute of Advanced Material Study, Kyushu University, Kasuga 816-8580, Japan) O" e. c; |* L1 M6 x
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Experimental and numerical studies are carried out for the conjugate heat transfer of an electronic module package cooled by air. Firstly, the heat conduction experiment was conducted to obtain the surface temperature profiles and to estimate the total conductive resistance and natural convection heat transfer rate to air from the outer wall of duct, where the same type two module packages were fixed opposite at the bottom and top inner walls of duct and glass wool was filled inside the gap. The measured temperature profiles were compared with those obtained by the corresponding numerical simulations and the heat transfer coefficient at the outer wall of duct was estimated. Secondly, the convective heat transfer experiment was done for a single module package attached on the bottom wall of the duct by switching three fans on and off in various combinations. As for the surface temperature profiles, the numerical results agree well with the experimental ones. When the thermal conductivity of printed circuit board is varied, however, the heat transfer coefficients based on the conventional definition could not be summarized with a unique correlation due to the effects of conjugate heat transfer. Introducing an effective heat transfer area has solved the problems and a unique correlation is proposed.Numerical simulations also clarified the effect of thermal conductivity ratio on the non-dimensional effective heat transfer area, and further the heat transfer characteristics when two or more module packages are set in the same duct.
