Cellulose-pad water cooling system with cold storage

• A cooling system utilizing natural energy from diurnal ambient air temperature difference.
• Water is cooled at night by cellulose-pad cooling tower and stored for cooling application at daytime.
• Overall COP can reach 9.4 for room temperature higher than 40 °C.
• Feasible for data center cooling.

The present study develops a cooling system using water as the working medium which is cooled at night by cellulose-pad cooling tower (CWCT) and stored for cooling application at daytime. That is, it utilizes the natural energy drawn from diurnal ambient air temperature difference. A cooling system was built and tested. It is found that the coefficient of performance of CWCT for heat dissipation of water at night, COPnt, is between 3.8 and 11 and varies linearly with the evaporation temperature glide DG (difference between cold water temperature in the storage tank and wet-bulb temperature of ambient air). The COP for room cooling at daytime run with air cooler in a room, COPday, is between 8.8 and 12.6. For day cycle operation, the measured overall cooling COPo is 5.1. COPo is expected to reach 9.4 at room temperature 45 °C.