Mass Transfer Enhancement And Optimization Design Of A Small Solar Absorption Air-conditioning Based On Ultrasonic Cavitation

With the improving of people’s life, the air-conditioning is becoming increasingly popular.But the compressed air-conditioning has some problems，such as environmental pollution,serious energy consumption and so on. The main advantage of solar air-conditioning is thatcoolings loads and slar gains occur at the same time, at least on a seasonal level, so the solarair-conditioning has a very wide application prospect. Research results show that the solarair-conditioning’s cooling efficiency of low-temperature segment is low. In this thesis, theultrasonic cavitation technology is applied to the generator of the solar absorptionair-conditioning. Experimental results show that the ultrasonic cavitation technology canimprove the refrigerating performance of the solar absorption air-conditioning in the lowtemperature. Finally a small solar absorption air-conditioning has been designed. The mainlyresearch works are summarized as follows:(1) Mechanism of enhancing mass-transfer process by ultrasonic cavitationThe mass-transfer process of the two-phase system by using the ultrasonic cavitationtechnology is deeply analysised from the angle of ultrasonic cavitation and its fouraccompanying effects. It provides theoretical supports for enhancing the refrigerant transferprocess by ultrasonic cavitation.(2) Feasibility analysis of enhancing the refrigerant transfer process by ultrasoniccavitationA solar absorption air-conditioning simulator is established and the feasibility ofenhancing the refrigerant transfer process by ultrasonic cavitation is verified by the methodsof weighing contrast and chemical preciption. Experimental results show that the ultrasoniccavitation technology can enhance the refrigerant transfer process.(3) Experimental study of the ultrasonic cavitation’s impacts on the refrigeratingperformance of the solar absorption air-conditioningThe ultrasonic cavitation’s impact on the refrigerating performance of the solarabsorption air-conditioning is studied in conditions of different heat source temperature andliquid height. Experimental results show that the ultrasonic cavitation technology can improvethe solar absorption air-conditioning’s coefficient of performance(COP) and reduce the heat source temperature by about5°C when the COP is the same. When the liquid height isbetween20～40mm, the refrigerating performance of the solar absorption air-conditioning isthe best.(4) Optimization design of a small solar lithium bromide absorption air-conditioningbased on the ultrasonic cavitationThe generator, evaporator, absorber and system accessories are all optimally designed andfinally a small solar lithium bromide absorption air-conditioning is designed. This system canexacerbate the boiling of the lithium bromide solution and enhance the refrigerant transferprocess by using the ultrasonic cavitation technology, which can improve the COP and therefrigerating performance of the solar lithium bromide absorption air-conditioning.