鉄道車両用電力変換装置の自然空冷(熱工学,内燃機関,動力など)  [in Japanese] Natural Cooling of Power Converter Units for Electric Trains(Thermal Engineering)  [in Japanese]

An optimization method for fin pitch in naturally cooled heat sinks is described. Because the heat sinks for the power units of electric trains are stacked vertically, lower heat sinks heat upper heat sinks. However the fin pitch of conventional heat sinks is optimized as single heat sink without accounting for the influence of the lower heat sinks. Equations to predict heat dissipation and a rise in exhaust air temperature in the heat sinks, along with an optimization method for the fin pitch are presented. These equations were carried out from a developed profile of velocity and temperature between two plates. A valid range of the Rayleigh number for the equations is shown, and the optimizing process for the fin pitch of stacked heat sinks is described. The experimental results of the rise in fin temperature of triple stacked heat sinks are compared with the calculated results. The heat sink with optimized arrangement of fins shows over 10% improvement in performance compared with the conventional heat sink.