Energy saving analysis of evaporative cooling composite air conditioning system for data centers

Highlights: • An evaporative cooling composite air conditioning system is proposed to save energy in data center. • Energy saving of the evaporative cooling composite air conditioning system is analyzed. • The annual performance factor values are 5.31, 5.02, 4.75 and 4.50, respectively in Shenyang, Beijing, Nanjing and Kunming. • The energy saving performance enhances after a water-cooled heat exchanger is used in the condenser. An evaporative cooling composite air conditioning system aimed at enhancing energy efficiency of data centers was proposed. Furthermore, the mathematical models on the base of the operation characteristics of the system were established. After verification by experiment, the energy saving performance of the system under different climatic conditions was investigated. The simulation results showed that the annual performance factor (APF) values are 5.31, 5.02, 4.75 and 4.50, respectively in severe cold zone-Shenyang (123.38E, 41.8N), cold zone-Beijing (116.30E, 39.9N), hot summer & cold winter zone-Nanjing (118.78E, 32.0N) and mild zone-Kunming (102.72E, 25.1N). The power usage effectiveness (PUE) values are below 1.40, the system has good energy saving advantages in different locations. After a water-cooled heat exchanger is used in the evaporative condenser, the APF values improve in all the four cities. The use of water-cooled heat exchanger is beneficial to further enhance energy saving of the system. A case study based on the system elaborates that it is feasible for energy saving of data centers in various climatic zones.