Dynamic model based study on mode switching characteristics and reliability analysis of data center composite air conditioning system

Abstract

The rack level composite air conditioning system is proposed to satisfy the cooling demand of the high heat flux density data center. The performance of the system relies highly on operating in proper mode in accordance with the ambient temperature. However, the large disturbance brought by the mode switching may cause risks like moisture condensation and insufficient cooling capacity, which significantly endanger the reliability of the data center. Hence, to investigate the mode switching period reliability of the system, a dynamic mathematical model was built and experimentally validated. Based on the model, the system transient response is obtained and the influence of outdoor temperature, compressor type and start-up strategy on the system reliability under mode switching period are analyzed. The results show, the delayed start of compressor accumulates significant heat when the system switches from evaporative cooling heat pipe mode to air cooling vapor compression mode, the heat can be dissipated in 341 s to 1920 s with different compressor type. The equipment of variable frequency compressor extends cooling capacity in the mode switching period while slightly increase the risk of indoor air moisture condensation.