Design And Performance Research Of Ejector In Central Air Conditioner Combined Solar Ejector Refrigeration System

Energy consumption of air conditioner is huge in large buildings, it can accounts for30%～50%of the whole building energy consumption in summer, so the cooler air conditioner energy saving is an important subject. Solar ejector refrigeration technology is applied widely owing to the ejector’s simple structure and small size. The solar ejector refrigeration technology combined with the central air conditioner, can not only improve the coefficient of single solar ejector refrigeration system and solve all-weather operation problem, but can reduce the energy consumption of central air conditioner. The central air conditioner is the main body, design a solar ejector refrigeration system based on the characteristics of central air conditioner is important. And the ejector is the critical part of the solar ejector refrigeration system, so the reasonable ejector design is the key.In this paper, ejector is designed by one-dimensional constant pressure design theory after the central air conditioner operation parameters is analyzed. With internal flow field characteristics and mixing mechanism is revealed by two-dimensional simulation in FLUENT, impacts of operating conditions and structure parameters on the ejector performance are researched. Structure parameters are optimized in theory while operating conditions influences are investigated in experiment. Comparisons of test and simulation results provide improvement direction. Main works as follows:1. Analyzing working process of the injector, thermal physical parameters polynomials of refrigerant R22in range of operation condition are fitted. Using the gas dynamic function united with theory of one dimension constant pressure, design method of the injector radial dimension is obtained. And the axial size is calculated refer to empirical formula. Whole calculation process is programmed in Visual Basic.2. On the basis of structure design, a two-dimensional axis symmetric model is made. After appropriate settings for numerical simulation, the velocity field and pressure field distribution in ejector at working condition are obtained and are compared with those at large expansion ratio. It finds that there are obvious differences in fields distribution and mixing process between working condition and large expansion after nozzle exit position.3. With this model the influences of entrainment at different outlet pressure, primary fluid pressure, secondary fluid pressure are simulated. And structural parameters of constant-area mixing section length and nozzle exit position are optimized combination. The entrainment change laws are achieved. The results show that, compared with primary fluid pressure, secondary fluid pressure change at small expansion ratio have a greater impact on entrainment; constant-area mixing section length at large expansion ratio has a compromise value while that at small expansion is appropriately short; the overlong length of constant-area mixing section at small expansion ratio could be improved with shortening of nozzle exit position.4. In order to investigate the experimental performance of the ejector, experiment rig of central air conditioner combined ejector refrigeration is established. The experimental entrainment at different outlet pressure, primary fluid pressure, secondary fluid pressure are tested and compared with simulation results. The curves have same change tendency although there is big deviation. The deficiencies are analyzed and improvement direction is proposed.