An experimental investigation of a heat pipe integrated power module
A novel flat plat heat pipe (FPHP) integrated in high power module instead of metal substrate is developed. Compared with the metal subtrate, the FPHP uses two-phase boiling heat transfer to diffuse heat flux in power module.Thus the FPHP diffuses significantly the collect heat source to the more larger condensation area. Analyze the use of a FPHP as a heat spreader to spread out the heat from the die to the heat sink.The transient and steady heat transfer performance of the FPHP was experimentally measured.The experiment indicates that the FPHP of isothermal and high convection coefficient can improve the heat transfer capacity for the integrated power electronic module (IPEM), which make thermal resistance decrease 30 percent. The maximum thermal flux density of IGBT die is obtained to 186 W/cm2. IPEM based on FPHP can avoid the power uprush and raise the ability of resisting thermal impact.
Temperature Variation and Heat Transfer in Triangular Grooves with an Evaporating Film
A mathematical model for the evaporating heat transfer coefe cient and temperature variation along the axial direction of a grooved plate has been developed. The model includes the effects of the capillaryinduced e ow in the grooves caused by the surface tension, the two-dimensional heat conduction occurring in the wall and liquid e lm, and the e ow and evaporation of the thin e lm caused by the disjoining pressure and surface tension in the thin e lm region. The results obtained from this model indicate that if a constant heat e ux boundary condition is applied, the heat transfer coefe cient will decrease and the wall temperature will increase along the axial direction. In addition, the apparent contact angle increases with increasing superheat, and hence, the heat transfer rate through the micro region also increases along the axial direction. Finally, it has been demonstrated that the contribution of the surface tension variation caused by temperature increases in the micro region can be neglected. This work will lead to a better understanding of the axial heat transfer coefe cient and temperature distribution on grooved surfaces, and how these parameters affect the e lm thickness.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.