Performance Research Of Solar Driving Ejector-Compression Refrigeration System

At present,refrigeration air condition mostly used a vapor compression cycle.Although this circular system had the advantages of more cooling capacity and high stability of control,while it needed to consume a large amount of electrical energy.As a technology of energy-saving,solar-ejector refrigeration system had been concerned by scholars for a long time.However,this system had problems about low performance coefficient and poor control stability,which limited the practical application of solar-ejector refrigeration system.In order to reduce energy consumption and increase the performance and stability of refrigeration systems,according to the characteristics of vapor compression cycle and solar-ejector refrigeration systems,the solar-driven ejector-compression hybrid refrigeration system has become a hot topic around the country.The solar-driven ejector-compression hybrid refrigeration system was taken as the object of research in this paper,the performance of variable workingconditon on the adjustable ejector with supersonic nozzle was analyzed by simulation and experiment,the performance of the adjustable ejector with two nozzles(subsonic nozzle and supersonic nozzle)was analyzed.Furthermore,basing on the simulation model,the performance of ejector-compression hybrid refrigeration system and the efforts of the middle heat exchanger temperature of ejector side on the performance of ejector-compression hybrid refrigeration system were investigated.Firstly,the assumptions and application ranges of the three ejector models in the literatures were compared.The ejector model for this paper was proposed by comparison and analysis of data.The ejector model was validated by the experimental value,the error between the simulation value and the experimental value was within±10%.Secondly,when the experimental system of adjustable ejector performance was taken as the object of research,the performance of the supersonic nozzle ejector was analyzed.Under the driving pressure was 2.117MPa and the ejector pressure was 0.571MPa,when the throat area of the nozzle increaseed from 0.964mm~2 to 1.327mm~2,the ejector ratio decreased from0.51 to 0.26,and the condensing pressure of critical point increased from 0.78MPa to 0.92MPa.The increasing of the throat area of nozzle and the increasing of driving pressure had similar effects on the performance of the ejector.Therefore,during the temperature of driving heat source was changed,the same ejector ratio of ejector could be achieved by changing the nozzle throat area.In addition,when the experimental system of adjustable ejector performance is taken as the object of research,the performance of the adjustable ejector was analyzed by configuration and opening of two nozzles.When regulating the performance of the adjustable ejector,the flow characteristics of driving flow on the nozzle outlet should be considered.For the ejector operating conditions for this paper,the supersonic nozzle could be selected under the outlet pressure of ejector was high and the operating conditions fluctuated small.During the operating condition fluctuated greatly,the subsonic nozzle was more suitable for the adjustable ejectorFinally,the performance of the ejector-compression hybrid refrigeration system was analyzed by the temperature of the middle heat exchanger on the ejector side under different configurations of nozzles.When input heat capacity of the generator was 2kW,the evaporating temperature was 8?,the condensing temperature was 40?,the driving temperature was 65?,the degree of superheat and supercooling was 2?,the temperature difference of heat transfer was 5?,the middle heat exchanger temperature of ejector side was 15~35?,the middle heat exchanger temperature of compression side was 20~40?,the maximum COP andcooling capacity of ejector-compression hybrid refrigeration system was 0.29 and 3.2kW using the ejector of supersonic nozzle.While the maximum COP and cooling capacity of ejector-compression hybrid refrigeration system was 0.093 and 1.27kW using the ejector of subsonic nozzle.Comparing to vapor compression cycle,during the cooling capacity was 2kW and the middle heat exchanger temperature of ejector side was 25?,half of power consumption could be saved by the ejector-compression hybrid refrigeration system using the ejector of supersonic nozzle.