Energy, exergy, and economic analysis of a data center energy system driven by the CO2 ground source heat pump: Prosumer perspective

Abstract

With increasing reliance on information technology by modern society, the scale and energy consumption of data centers (DCs) are rising rapidly. Approximately 40% of the energy consumed by DCs is associated with refrigeration systems used to maintain optimal operation temperatures. Such systems produce large amounts of waste heat; therefore, the utilization of the waste heat is essential for the optimization of the energy efficiency of DCs, especially with regard to DC prosumers (producers and consumers). However, the low temperature of the waste heat and variation in load demand are two factors limiting the exploitation of waste heat from DCs. In this study, a prosumer DC energy system based on a ground source heat pump (GSHP) is proposed for the recycling of waste heat from DCs for the heating of surrounding buildings. The heat generated in the non-heating period is stored in the soil and made available for building heating using a carbon dioxide (CO2) direct-expansion GSHP. Furthermore, the cooling power consumption, total power consumption, exergy efficiency, and net profit of the prosumer DC waste heat energy recovery system are evaluated. Compared to conventional cooling systems that use air source heat pumps (ASHPs) for building heating, the energy, exergy, and economic (3E) performance of the prosumer DC have the following advantages: 1) the prosumer DC waste heat energy recovery system yields a heat-power ratio of 5.70, with a total power consumption approximately half (52.86%) that of the conventional system; 2) the matching thermodynamic properties are greatly improved; specifically, the exergy efficiency of the prosumer DC waste heat energy recovery system is 3.87 fold that of the conventional system; 3) better economic revenue of the prosumer DC waste heat energy recovery system generates more economic revenue, with an annual net profit approximately 190.34% of that generated by the conventional system. In general, the prosumer system facilitates flexible and effective utilization of the low-temperature waste heat, by coupling the upstream power supplier and downstream thermal users through a GSHP.