Estimation of an overall cooling performance in electronics thermal design: the case of forced convection

摘要

Several methods to improve beat transfer arid enhance the capability of convective cooling in electronic equipment, also tend to cause an increase in the pressure drop.A long-standing issue, not only in electronic equipment thermal design but also in conventional design or heat transfer apparatuses, has been how to properly trade-off the advantages of improved heat, transfer and the disadvantages of an increase in thepressure drop.The goal of the present paper is to estimate the overall performance of convection cooling for electronic equipment using entropy production rates derived from either the heat transfer or the pressure toss terms. Some theoretical results are presented for the case of forced convective cooling for a model inside a circular tube. Corelation with experimental results are also described for a test module having a certain characteristics of thermal resistance.The overall performance of convective cooling can be determined by plotting the entropy production rate against the change in flow velocity or the change in heat transfer area. The expected minimum points are clearly shown for a certain value of variableparameters, which means the advantages and disadvantages of the cooling capability and the pressure drop are balanced.And the problem of a "size(volume)" of a heat transfer system is considered, which necessarily accompany the entropy-based estimation criteria.The present criterion is compared with the conventional ones from a view point of thermal design of universal heat exchanger systems.