Enhanced geothermal system with CO2 instead of water as the working fluid (CO2–EGS ) has attracted much interest due to the additional benefit of CO2 geological storage during the power generation process. This paper describes numerical analyses of a doublet CO2–EGS system, focusing on the...

Air-to-water heat pumps using CO2 as a natural refrigerant have been developed and commercialized. They are expected to contribute to energy saving in residential hot water supply. The objective of the research is to analyze the performance of a water heating system composed of a CO2 heat pump...

In residential applications, an air-to-water CO2 heat pump is used in combination with a domestic hot water storage tank, and the performance of this system is affected significantly not only by instantaneous ambient air and city water temperatures but also by hourly changes of domestic hot...