Experimental study on dynamic thermal characteristics of novel thermosyphon with latent thermal energy storage condenser

Abstract

Emergency cooling systems are an essential part of data centers. A water tank is usually used as an emergency cooling source to provide cold thermal energy; however, tanks are bulky and additional uninterrupted power supplies (UPSs) are needed. For flexible emergency cooling, a novel thermosyphon integrated with a latent thermal energy storage condenser (TLTESC) is developed and experimentally studied. The effects of the refrigerant filling ratio and inlet conditions on the dynamic thermal performance are analyzed. With an increase in the refrigerant filling ratio from 48.7% to 82.5%, the cooling capacity decreases; the maximum cooling capacity decreases from 4.68 to 2.03 kW. The superheating temperatures for all cases are always zero, indicative of the two-phase refrigerant being at the evaporator outlet. During the entire operating period, the refrigerant temperatures at the vapor line are considerably higher than those at the liquid line. Moreover, the refrigerant pressure at the evaporator inlet is the highest. Under the optimal filling ratio, the outlet air temperature increases and the maximum cooling capacity increases from 3.6 to 4.8 kW with the inlet air temperature increasing from 30 to 40 °C. The cooling capacity increases with air flow rate during the first half, after which the situation is reversed. The accumulated energy increases slightly as the air flow rate increases. The thermal performance is investigated to promote the application of TLTESC in data center.