Study On The Adjustable Ejector And The Bi-ejector Refrigeration System

For the purpose of achieving energy-saving, emission-reduction and the effective use of renewable energy, we can use solar energy, factory waste heat and other low grade energy for refrigeration and air conditioning. As the ejector refrigeration system has the advantages of simple structure, reliable operation, low maintenance cost, the ejector refrigeration system has been paid more and more attention.In this paper, a comparative analysis has been made on the existing ejectors and ejector refrigeration systems, on this basis, a kind of adjustable ejector was presented. Under varying operating conditions, by rotating nozzle and cone, the adjustable ejector can realize the adjustment of the nozzle’s axial position and throat area to achieve stable operation. By adding a gas injector, a bi-ejector refrigeration system has been presented, and the mathematical model of the system has been established. Combined with the use of solar energy, this paper further presents a solar-powered bi-ejector pump-free refrigeration system, modeling and simulation analysis has been made.The conclusions of the study show, the jet coefficient of the injector’s will decrease with the increase of the injector’s nozzle throat diameter, and will increase with the increase of the distance between nozzle and mixing chamber; the COP of the solar-powered bi-ejector pump-free refrigeration system will increase with the increase of solar collector inlet fluid temperature, generator temperature and evaporator temperature, and will decrease with the increase of condenser temperature; With the increase of solar collector inlet fluid temperature, the system’s refrigerating capacity will increase, and has the same regular as the solar irradiance changing with the time; compared with the solar-powered single ejector pump-free refrigeration system, when compression ratio is greater than 8, the system’s COP is improved by more than 20%.