Evaluation of the cooling effectiveness of air-cooled data centers by energy diagram

Data centers are one of the world's largest energy consumers, and their cooling systems contribute to the majority of the total energy consumption. Although some studies have suggested evaluation metrics, the cooling capacity utilization in the computer room of air-cooled data centers is still not able to be directly quantified. In this paper, the dimensionless index Effective Cooling Ratio (ECR) is proposed for the first time to evaluate the energy efficiency of the cooling process in air-cooled data centers. By decoupling the cooling process of the computer room, the energy diagram is developed to analyze the thermal energy changes of each phase. Moreover, the proving of this approach is carried out with computational fluid dynamics simulation; three data center models are investigated, and the results demonstrate the good performance of the enclosed aisle. This metric not only provides a valuable tool for quantifying the cooling and energy performance within data centers but also suggests ways to improve the energy efficiency of data centers.