The solar-air dual-source heat pump technology is based on the application of solar energy and air energy as the heat source of the heat pump system. It is a comprehensive utilization of the solar energy and the air energy , and it can be a good solution to the low efficiency, the non-stability and the poor reliability of the air-source heat pump in winter. In the paper, the development of different types solar-air dual-source heat pump system in China have been discussed, and the characteristics of the different heat pump systems have been analyzed. Based on the analysis results, a new solar-air dual-source compound heat pump system has been constructed.
Keywords-solar-air, dual source heat pump, research status
I. INTRODUCEAir is a clean, safe, inexhaustible natural energy.Because of the less energy consumption, the limiting contribution to the environment problems and other good performance of the air source heat pump, it has been generally received lots of attentions. Although the simple structure and the convenient installation of the air source heat pump, the application has been limited by the ambient temperature. Its heating capacity and the heating performance coefficient will greatly decrease as the ambient temperature decreases, and the cooling and the heating capacity are difficult to be suitable to the building load.Moreover, it has the outdoor frost problems in winter, so it is not suitable to the cold regions.As is well known, the solar energy is the source of all energy on the earth. Like air, it is a safe, inexhaustible natural resource. If the solar energy and the air energy are used as the heat source of the heat pump system at the same time, the performance and the reliability of the air source heat pump will be greatly improved. The solar-air dual-source heat pump system has achieved the composite application of the solar energy and the air energy, and it can meet the requirements both of the space heating or cooling and the domestic hot water. The relative research about the solar-air dual-source heat pump technology have been carried out in lots of universities, such as Southeast University, Nanjing University of Science and Technology, Qingdao Technological University, Zhongyuan University of Technology and so on. II. THE ALTERNATIVE SOLAR-AIR DUAL-SOURCE HEAT PUMP SYSTEM Figure 1. The alternative operating mode of the solar-air dual-source heat pump system The solar-air dual-source heat pump system with the alternative operating mode comprises of a water evaporator and an air evaporator, as shown in Figure 1. The heat source of the heat pump system may be provided with the ambient storage water tank pump water evaporator compressor condensor power user expansion valve air evaporator solar energy collector triple valve