Investigation On Solar-powered Passive Ejector Cooling System

The working principle and system performance of a solar-powered passive ejector cooling system is studied in this paper. The system is powered by solar thermal energy, using gravity head to transfer liquid from the condenser to the boiler. This system can work easily and economically, and it contains no active parts and is therefore deemed passive.In this paper the resource distributing and the characteristic of solar energy, the computation of solar radiation and the heat transfer model of evacuated tube collector are described and analyzed. The principle and characteristic of ejector cooling system is discussed in detail. The design procedure of the ejector and the method to calculate the flow ratio for the ejector (the mass flow rate from the evaporator and boiler) is also mentioned. The computer program to calculate the flow ratio for the ejector is also made. The components of the passive ejector cooling system and the choice of working fluid are discussed. The influences of the boiler temperature, the condenser temperature and the evaporator temperature on the COP (coefficient of the performance) are analyzed. Under different solar radiation, the numerical simulation on the cooling capacity and the COP of the solar-powered passive ejector cooling system in a day is carried out. The calculated results show that the COP and cooling capacity increase with increasing of solar radiation intensity, and the volume of hot water tank has a significant effect on the system performance. The system design and analysis combined with a floor heating system to make the solar-powered passive ejector cooling system to be used in a building are also considered and analyzed.The results show that the COP of the solar-powered passive ejector cooling system is lower, but by virtue of the system's merit in energy saving and environment protection, and by the development of the solar collector and ejector technology, as well as the improvement of building structure combined with solar energy utilization, this system could be widely used in the ecological buildings.