Experimental Study on a Pump Driven Loop-Heat Pipe for Data Center Cooling

An experimental study on a pump-driven loop heat pipe (PLHP) charged with R22 for cooling a data center is reported in this paper. The PLHP had five tube-fin heat exchangers as evaporators and three tube-fin heat exchangers as condensers, a liquid reservoir, and a canned motor pump. The coefficient of performance of the unit was 3.75 when the indoor-outdoor temperature difference was 10 degrees C, then increased to 9.37 when the temperature difference was 25 degrees C. The mass flow rates of R22 increased from 200 to 1,100 kg= h with one evaporator and one condenser of the PLHP, and the heat transfer rates first increased and then decreased. When the vapor quality of R22 at the evaporator outlet was between 0.3 and 0.6, the mass flow rate affected the heat transfer rate slightly. As the increase of mass flow rate in the PLHP, the temperature difference between the evaporator inlet and outlet, and the sensible heat ratio were both rising. When the mass flow rate was about 1,400 kg/h and the indoor-outdoor temperature difference increased from 10 to 30 degrees C, the relationship between the heat transfer rate and the temperature difference was (C) 2014 American Society of Civil Engineers.