Thermodynamic analysis of a novel combined cooling, heating, and power system consisting of wind energy and transcritical compressed CO2 energy storage

Abstract

Due to climate change and the increase in energy demand caused by population growth, considerable attention is being given to wind energy and combined cooling, heating, and power (CCHP) systems, which are known for their high energy utilization. With the rapid growth of wind power generation, the waste heat generated by wind turbines and the intermittency of wind power have emerged as problems to be addressed. Therefore, this paper proposes a low-temperature CCHP system based on transcritical compressed CO2 energy storage which utilizes wind power and wind turbine waste heat. A mathematical model of this system is developed and applied, and system characteristics are evaluated from the perspective of thermodynamics. The performance indices (system power efficiency (SPE), system energy efficiency (SENE), and exergy density (ED)) are defined, and sensitivity analysis of the key factors affecting system performance is conducted. Based on the parameters under the design condition, the SPE of the system is 0.48, the SENE is 1.19, and the ED is 11.51 kWh/m3. Storage pressure and waste heat temperature have a great influence on the thermodynamic performance of the system, while ambient temperature only affects cooling energy, heating energy, and ED. The variation of the pressure difference at the main throttle valve mainly affects SPE and ED of the system.