Operating parameters optimization of a thermosyphon and compressor system used in 5G TBS

The free cooling technology is an effective way to reduce the energy consumption of an increasing number of 5G telecommunication base stations. In this paper, a parallel hybrid cooling system of thermosyphon and vapor compression for free cooling used in 5G telecommunication base stations has been proposed. The energy efficiency ratio (EER) is experimentally investigated in a simulated base station under different working conditions and operating parameters. The results indicate that operating parameters such as setpoints of return air temperature, evaporator and condenser fan speeds can significantly affect the natural cooling source utilization ratio of the hybrid cooling system, thereby affecting the EER of the system. When the outdoor temperature is less than 20 °C, the variation of evaporator fan speed will have a significant impact on the operating mode of the system. An appropriate evaporator fan speed can reduce the proportion of compressor operating time to 0%. At an outdoor temperature of 15 °C, optimizing the evaporator and condenser fans speeds can improve the EER by 60% and 52%, respectively. However, when the outdoor temperature exceeds 25 °C, the system always operates in air-conditioning mode, resulting in the system's EER being minimally affected by the fans speeds. While ensuring the safe operation of communication equipment, optimizing the evaporator fan speed and setpoint temperature simultaneously can increase EER from 3.18 to 17.19.