High-temperature heat pumps are an important means to solve the dual utilization of cold and heat and realize energy saving and emission reduction. Owing to the limitation of refrigerant use

natural working fluid has become the focus of research. As a natural working fluid

ammonia has excellent thermal properties. In this study

the performances of ammonia and other commonly used working fluids for heat pump were compared and analyzed by thermal calculations and the research progress on ammonia vapor compression high-temperature heat pumps were summarized. It is shown that ammonia has the highest overall performance in the range of 80–95 ℃ and is suitable for high temperatures of 60–110 ℃. Based on the single-stage vapor compression cycle

an ammonia high-temperature heat pump system using solar energy compensation is proposed and its feasibility is discussed in combination with the solar radiation conditions in Tianjin.