Research On A Novel Evaporative Cooling-Ejector Refrigeration Airconditioning System

Today,with the increasing energy consumption and environmental issues in the world,refrigeration technologies using renewable energy and low-grade heat sources,such as,last heat or waste heat have received extensive attention in the field of HVAC.In recent years,due to the high energy consumption problems caused by mechanical compression refrigeration technology,ejector refrigeration technology and evaporative cooling technology have been proved their advantages in energy saving and emission reduction.The ejector refrigeration system is a low-grade heat-driven refrigeration cycle.The ejector replaces the compressor,without the oil return,operating with little maintenance,low power consumption,and high reliability.The indirect evaporative cooling technology utilizes the temperature difference between the ambient dry bulb temperature and the wet bulb temperature to obtain cooling through heat and mass exchange between air and water,which is an environmentally friendly,economical and efficient cooling method.It effectively reduces the cost of the equipment and costs of the operating,provides lots of fresh air and effectively reduces the air age.Combining two kinds of refrigeration technologies,this paper establishes a new type of evaporative cooling-ejet or refrigeration air conditioning system,analyzing the system theoretically and conducting experiment.The purpose is to demonstrate the feasibility of the new evaporative cooling-ejetor refrigeration air conditioning system.The application provides a theoretical and experimental reference.The main work is as follows:?1?The new evaporative cooling-ejetor refrigeration and air conditioning system was designed,and the principle of the system working was explained.The thermodynamic calculation model of the composite system and the heat exchanger was established by thermodynamic method.?2?Calculate the size of ejector design and the ejetor refrigeration subsystem cycle with the EES programming procedure and the gas dynamics function method.By comparing the thermophysical properties of different refrigerants,the refrigerant R245fa was selected as the refrigerant for the ejector refrigeration sub-cycle.?3?Analyze the system performance of the ejector refrigeration sub-system,establish a one-dimensional ejector model.Analyze the state parameters of the primary fluid,the secondary fluid and the mixed fluid about the ejector coefficient and change through thermodynamic calculation and analysis methods to improve injector performance and system performance.Calculate the thermophysical properties of R245fa on each state point in the sub-system,T_eva=15?,T_con=35?,T_gen=110?and?=0.5537.?4?Build a new evaporative cooling-ejetor refrigeration air conditioning experimental system,using the evaporative cooling sub-system as the air pre-cooling system and the ejetor refrigeration sub-system as the air re-cooling system.In order to make full use of the exhaust air cooling,the exhaust air blows through Air cooling condenser of the ejector refrigeration sub-system.The ejector,pressure vessel,tubular indirect evaporative cooler,etc.are designed and other components are selected.?5?With the adjustment of the working conditions,the matching of the composite system is realized,the feasibility of the new system is demonstrated,the theoretical design of the composite system is verified,and the adjustment of the air is realized,The parameters of supplied air were processed by the dry bulb temperature from39.37?to 20.6?and the wet bulb temperature from 20.1?to 14.1?,resulting in a enthalpy difference of 18.6 kJ/kg.In the ejector refrigeration sub-system,under the experimental conditions,the entrainment ratio reaches 0.4,the coefficient of performance is 0.17,the cooling capacity of 0.99 kW is provided.The COP of air-conditioning system is 0.274.In production,the heat source of the generator comes from waste heat.After ignoring this part,the COP can reach 0.914,which demonstrate the feasibility of a new system and can be further studied experimentally.In this paper,there are 54 figures,14 tables and 72 references.