In this study a refrigerant pump-driven heat pipe and vapor compression composite cooling system with an evaporative condenser was proposed to solve the problems of high energy consumption and low cooling efficiency of traditional data center cooling systems. Through experimental research

the operating performance of this system under different outdoor temperatures and air velocities of condenser was analyzed. The results show that in the heat pipe mode

when the outdoor temperature is lower than 0 °C

reducing the air velocity of condenser can increase the system coefficient of performance (COP) and effectively prevent condensation in the evaporator. The evaporation temperature increases by 1.8 ℃ on average for every 1 m/s decrease in the air velocity of condenser. When the outdoor temperature is higher than 0 °C

increasing the air velocity of the outdoor unit can improve the energy-saving performance of the system. Compared with air cooling

when the outdoor temperature is 5–10 °C

the COP is increased by 15.5% on average after the evaporative-cooled mode is turned on. At the same time

evaporative cooling also enhances the cooling capacity of the system

increasing the upper limit of the outdoor temperature in the heat pipe mode from 10 °C to 15 °C. In the vapor compression mode

evaporative cooling can effectively improve the energy efficiency ratio of the system. When the outdoor temperature is 30 ℃

after the system is switched to the evaporative-cooled mode

the COP is increased by 17.5%

16.2%

and 14.3%

respectively under the three air velocity of low (1.5 m/s)

medium (2.5 m/s) and high (3.5 m/s).