Experimental study and analytical modeling of thermosyphon loop for cooling data center racks

This paper presents experimental study and analytical model for a passive two-phase thermosyphon loop designed to remove directly the hot air flow inside a data center. The cooling loop with separated lines working without electricity is tested under different conditions. A mini-channel parallel-flow evaporator and a finned-tubes condenser are used to transfer heat from the data center to outside environment. Experimental tests are conducted with different n-pentane fill ratios. According to these tests, the cooling performance is showed and the refrigerant distribution is specified. The proposed steady-state model is based on the combination of the thermal and hydraulic models of the two-phase flow inside the loop. It well predicts the experimental results such as the mass flow rate and working fluid pressure drops. As investigated by the model, the most parameters influencing the cooling capacity are: the working fluid, the condenser tubes number and the outside temperature.