Editorial: CO2-based energy systems for cooling, heating, and power

Abstract

Copyright © 2022 Li, Su, Xu, Dai, Li and Li. As a natural working fluid, carbon dioxide (CO2, R744) has attracted the widest attention for the next-generation energy systems to tackle climate change due to its extraordinary thermophysical properties and environmental friendliness of zero ODP, low GWP (∼1), non-toxicity, and non-flammability. These targeted applications include both the standalone refrigeration systems, heat pumps, and the power generation systems, and the cogeneration systems by integrating the cooling, and/or heating, and/or power subsystems to meet various demands. Despite the ongoing research from academia and industry, there are indeed, theoretically and technically, remaining challenges that slow down the advancement of such applications and need to be solved. There is always a tradeoff between the efficiency improvement and the cost reduction. Besides, the development of the key components is still somewhat weak, such as the high-temperature CO2 compressor, highly efficient CO2 expander especially at a power scale of several and several tens kilowatt, compact gas cooler and gas heater, which requires dedicated structure design and material evolution. Moreover, the cooling of CO2 working fluid is very challenging owing to its near ambient critical temperature (31.1°C), which leads to working fluid exploration by CO2-based mixture or blends. Due to these limitations, at present, the CO2-based energy systems are seldomly demonstrated and there is a lack of experimental study to identify their potential. This topic explores the thermo-economic analysis of the CO2-based standalone and cogeneration energy systems for cooling, heating and power, experimental investigation on the systems and the key components of such systems, and other relevant advanced energy systems. It concludes with six peer-reviewed journal papers to promote research, sharing and development.