Search

This study describes the transient temperature distributions in a cooling apparatus for high-power semiconductor devices used in electric-railcar drive systems. The cooling apparatus is composed of heat pipes, air-cooled fin arrays, and a metal block which is used for attaching several semiconductor packages, In our numerical simulation model, we substituted solid elements for the heat pipes, and determined their thermal properties by experiment. As a result, we could obtain transient temperature distributions for the cooling apparatus through a heat conduction analysis. Calculated results showed that when the amount of heat generated in the devices changes, the temperature of the cooling apparatus changes more slowly than that of the devices. A comparison between the transient-temperature distribution calculations and the experiments confirmed the accuracy of the modeling and prediction method. Thus, these calculations can be used to provide data for packaging design, especially concerning thermal stress and fatigue in the packages. © 1998 Scripta Technica, Inc. Heat Trans Jpn Res, 26(2): 107–115, 1997

The heat transfer performance of coaxial straight heat pipes in high-speed rotation has been analyzed. The parameters are the geometry of the pipe, the kind of working fluid, the mass of the working fluid charged in the pipe, the rotation rate and the heat load. As a result of the analysis, the distribution of film thickness in the pipe, the Nusselt number of the evaporator and condenser section, and the dryout conditions at the end of the evaporator section were found. The Nusselt number from the present analysis is compared with the experiment by Ohtsuka et al. The predictions are is good agreement with the experimental data in the condenser section, but are about 80 100% lower in the evaporator section.