Study On The Ejector-compression Coupled Refrigeration System Based On The Classified Utilization Of Solar Energy

It has become a tendency to utilize the solar air conditioner to reduce the building energy consumption and alleviate the problem of energy shortage.This thesis puts forward a kind of ejector-compression coupled refrigeration system,which is based on the classified utilization of solar energy,and studies on the performance of the system.The thesis is aimed at realizing the effective utilization of the solar energy with different intensity,improving the utilization rate of solar energy and reducing the energy consumption of the air conditioner system,so as to achieve the best results of power saving and energy saving.The research is mainly described on the following aspects:(1)Set up a performance calculation model of the ejector in whole operational zone to study on the performance of the ejector.Based on the constant pressure mixing theory,set up the performance calculation model of the ejector critical point,thereby,set up the operational mode calculation model of the ejector critical point;based on the constant pressure disturbance hypothesis,set up the performance calculation model of the ejector breakdown point,and couple the model of ejector critical point and breakdown point and the operating characteristic equation of the ejector to set up the calculation model in the subcritical operational mode;by use of the EOC analytical method to analyze the influence of the part efficiencies on ejector performance.The critical point performance is mainly effected by ef and mf,while the breakdown point is mainly effected by mbf.According to the study and the experimental data,the part efficiencies equation is put forward.The accuracy degree is superior to the existed model at the present stage.In the whole operational zone of the ejector,the predicted maximum error of this model is no more than 10%.(2)Set up the exergy analysis and energy analysis model of the ejector-compression coupled refrigeration system of solar energy,and analyze the influences of the operating parameters of generating temperature,medium temperature,condensing temperature and evaporating temperature on the system exergy lose and system performance.Through the analysis,the author finds that based on the heat exchange amount of the generator and the heat-collecting capacity of the collector,the thermal performance coefficients COPh and COPs rise along with the going up of the generating temperature and evaporating temperature,and decrease along with the going up of the medium temperature and condensing temperature;based on the input mechanical energy,the mechanical performance coefficient COPm rises along with the going up of the medium temperature and evaporating temperature,and decreases along with the going up of generating temperature and condensing temperature;while in the state of exergy lose,rises along with the going up of condensing temperature,decreases along with the going up of the medium temperature and evaporating temperature,rises first and then decreases along with the change of generating temperature.According to the analysis results,the author sets the optimum generating temperature 80?,and the medium temperature 24?.(3)Set up the ejector-compression coupled refrigeration system based on the classified utilization of solar energy and put forward the operation strategy,and establish the mathematical models of the system main parts,such as generator,evaporator,condenser and evaporative condenser,so as to establish the basis of the calculation analysis of the system cooling performance.(4)Based on the TRNSYS software and the system parts model,establish the simulation model of the ejector-compression coupled refrigeration system based on the classified utilization of solar energy,which is used as the typical building cooling,and the analysis system provides the performance characteristics and rules to the building.The study chooses the workshop of a company in Taiyuan city as the cooling building,whose maximum cooling load is 19.8kW.This thesis designs the subsystems of solar heat collection,ejector refrigeration and compression refrigeration,as well as the cold accumulation system,and puts up the energy saving control strategies.Hereby,conduct simulation analysis of the cooling characteristics of the coupling refrigerating system of the targeted building in the succession typical days of July 9th to July 13 th.Results indicate that the covering and undercooling mode provide the most cooling capacity to the targeted building.In addition,compared with the traditional compression refrigerating system,this system can save the energy of 40%,and has a better energy-saving effect.