Copper-water loop heat pipes for energy-efficient cooling systems of supercomputers

An implementation of a cooling system with a loop heat pipe for thermal control of supercomputers is considered. For this purpose two copper-water loop heat pipes (LHPs) with an effective length of 400 mm and ID/OD diameters of the vapor lines of 3/4 and 4/5 mm correspondingly were designed and tested. The LHPs were equipped with a flat-oval evaporator with one-sided heat supply. The evaporator had a thickness of 7 mm, a length (including the compensation chamber) of 80 mm and a width of 42 mm. The influence of the cooling temperature of the condenser on the LHP operating characteristics was the central issue of this research. Tests were conducted in the range of the cooling temperature from 20 to 80 °C. The heat load supplied to the evaporator was varied from 20 to 600 W. A mathematical model for prediction of the LHP's operating temperature has been developed. It takes into consideration three operating modes of a loop heat pipe. Modeling results and their analysis are presented.