High-Temperature Industrial-Scale CO2 Heat Pumps

This technical report presents a detailed analysis of high-temperature industrial-scale CO2 heat pumps, focusing on their thermodynamic performance and pilot-scale testing results. The report outlines the limitations of conventional heat pumps that utilize hydrofluorocarbon (HFC) and hydrofluoroolefin (HFO) refrigerants, particularly their inability to operate effectively at temperatures above 120 °C. It discusses the advantages of using carbon dioxide (CO2) as a refrigerant, including its thermal stability and non-flammability, which enable higher temperature applications ranging from 150 to 400 °C. The report describes the innovative cycle architectures developed to enhance the performance of CO2 heat pumps, including the use of oil-free turbomachinery and the implementation of recuperators to optimize heat transfer. Additionally, it details the results of pilot-scale testing, which validate the performance of the new heat pump cycles under various conditions. The findings contribute to the understanding of CO2 heat pump technology and its potential role in decarbonizing industrial heating processes.