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.
Charge optimization for a triangular-shaped etched micro heat pipe
An analytical model considered to be the first analytical micro heat pipe model to predict the capillary limit of operation as well as the radius of curvature in the evaporator section and the optimal value of liquid charge was developed for a triangular-shaped, etched micro heat pipe. This model predicted optimal liquid prime values between 16-25% for various power levels and also indicated an optimal charge value which would not exceed 25%. Micro heat pipe arrays with liquid prime values ranging from 10 to 50% were used. The model was validated by comparing the predicted values of maximum heat transport capacity with experimental data at various liquid fill ratios. Although the model correctly predicted the trends associated with the variations in the fill ratio, significant differences were evident in the predicted and measured dryout level. 8 refs.