Experimental Study On The Performance Of A Pump Free Jet Refrigeration System

The high demand of global energy consumption and the environmental issues have imposed us to use the low-grade thermal energy.Ejector refrigeration system is an attractive solution to recover the low-grade thermal energy such as solar thermal energy and waste heat,which can use environmentally friendly fluid such as water.Furthermore,it also has more advantages including simple structure,low initial investment,and steady operating.In order to improve the performance of the ejector refrigeration system,and make ’it fully powered by heat,the operating characteristics of the no-pump valve switching ejector refrigeration system is theoretical and experimental investigated in this paper.The main research contents are as follows:1)The operating principle of the ejector,the research status of the ejector refrigeration system,and the factors affect the work efficiency of the ejector refrigeration system are introduced.The control and measurement accuracy of the system are improved and the operation process is simplified based on the improvement of existing no-pump valve switching ejector refrigeration system.2)A 1D model with constant pressure is introduced to theoretical investigation on the ejector.The effects of the generation pressure,condensation pressure,and evaporation pressure on the system performance are obtained.In addition,the fluid reservoir is designed based on an analysis for the influence of the fluid reservoir volume to the system stability.3)According to the analyze on operating principle of the no-pump valve switching ejector refrigeration system,the optimal system performance can be obtained as the fluid reservoir is full at the storage water time and the water is returned completely at the return water time.Therefore,the storage water time and return water time should be determined by the specific operating condition and the volume of the fluid reservoir.When the system is operated at the optimal condition,the performance of the no-pump valve switching ejector refrigeration system first increase and then decrease with a rise in the generation pressure.There exists a maximum system performance at the generation pressure of 130 kPa.And the performance of the system increases with a risen of the evaporating pressure.When the condensation pressure is smaller than the critical back pressure,the system performance is not influenced by the condensation pressure.However,when the condensation pressure exceeds the critical back pressure,the system performance is decreased dramatically with the condensation pressure increasing.4)The experimental results and theoretical calculation reveal the effects of the generation pressure,condensation pressure,and evaporation pressure on the operation parameters and performance of the system during working process.The calculated results agree well with the experimental results.The study in this paper has laid the foundation for the further study of the no-pump valve switching ejector refrigeration system.