18 May 2017

P.4.9.1 Study on the Performance of a Variable Geometry Ejector

In this research, experimental investigation has been conducted on the variable geometry ejector performance in order to use the unstable solar heat as the driving energy on the ejector refrigeration system. A supersonic nozzle and a subsonic nozzle were adopted in the ejector to verify the influence of nozzle configuration on the ejector performance. In the experiment, the generating temperature were regulated between 60 ºC to 80 ºC. The nozzle throat opening were adjusted to achieve the highest ejector performance. The results show a close relationship between the driving flow condition and the ejector performance. A supersonic nozzle can provide high ejector performance when the driving flow reaches ideally-expanded condition at the optimum nozzle opening for the ejector performance. Meanwhile, a subsonic nozzle provides stable performance under a various range of configuration regulation. Therefore, the nozzle configuration should be selected based on operating condition. In addition, the variable geometry ejector can ensure a stable performance for the ejector refrigeration system with unstable energy input. The results are significant for improvement of ejector performance in solar energy utilization.