Investigation Of LHP Based On Ni-Cu Wicks

Loop Heat Pipes (LHP) is one of the heat control technology based on divided Heat Pipe. Due to its high heat transfer capacity, flexible tube, anti-gravityability, long transfer distance, and high reliability, LHPs have widely prospect in the realm of heat-controlling spacecraft and electronic devices.In this work, LHP and wicks were fabricated. The effect of Ni-Cu ratio and sintering parameters on wicks were analyzed. As wicks with different Ni-Cu ratio reflect vary properties in pore size, porosity, permeability, and thermal conductivity, a new type of cylindrical wick which possessed different thermal conductivity between inner layer and out layer, was proposed. The LHP with bi-thermal-conductivity wick was tested with the fluid of water and ammonia, it showed that the LHP system with bi-thermal-conductivity relieved the heat leak and increased the temperature difference between evaporator and compensation chamber. The maximum temperature difference were55℃and40℃respectively in LHP-water system and LHP-ammonia system, that mean the compensation chamber could regulate the temperature of evaporator better and increased the capacity to against heat impact. Both the LHP-water and LHP-ammonia system could start-up and operate well under vary heat load, and the LHP system had nice self-adapting property. There were three types of temperature oscillation observed during the experiments:low width and low frequency oscillation in evaporator wall, high width and high frequency oscillation in tube, and sudden temperature drop during operating.