Study On Heat Transfer Performance Of LHP

With the development of technology, the integration of semiconductor devices has been greatly enhanced, and electronic devices tend to high-capacity and miniaturization. It results in the dramatical increasing of chip power consumption in unit volume, and brought a fatal problem of high heat flux. At present, the thermal control of the chip with high heat flux has become one of the key problems to restrict the technological development of the highly integrated chip.At present, the study of thermal control focuses on the phase-change cooling technology and heat pipe have been paid great attention. But the conventional heat pipe is restricted by some operational limits, such as continuous flow limit, frozen startup limit, viscous limit, sonic limit, entrainment limit, capillary limit, boiling limit and condensing limit. These limits result that the conventional heat pipe isn't the most efficient solution for the problem of high heat flux. Loop heat pipe has become a hot topic to settle this problem for its excellent heat transfer proformance with the reasonable operational process of evaporation and condensation. It has been applied in the cooling of electronic and aerospace equipment area.This paper presented several major factors impacting on the performance of sintered wicks. Loop heat pipe with three kinds of capillary layer thickness (3mm, 5mm and 7mm) were designed and manufactured. To study the performance of these loop heat pipes, measurement system was put up. Abundant experiments were conducted to research the effect of the capillary layer thickness and cooling conditions of conpensation chamber on start-up behavior and the impact of the capillary layer thickness, location of condenser and heat load on heat transport characteristics. The conclusion is following:(1) With the increasing of the capillary interlayer thickness, the startup performance of loop heat pipe is more superior.(2) When the radiator is installed on the compensation chamber, the loop heat pipes have better start-up performance.(3) With the increasing of the capillary interlayer thickness, the heat transport properties of the loop heat pipe improved significantly.(4) The heat transport characteristics of the loop heat pipe appear periodic changes with the change of the heating powe. It indicates that the loop heat pipe has more stable performance characteristics and can be applied to the conditions with stable and unstable heat load.(5) The location of condenser has a great impact on start-up performance and heat transport characteristics of the loop heat pipe.