Optimization And Experimental Study Of Air Side Fin Parameters Of Parallel Flow Heat Exchanger In Dry Condition

The temperature and humidity independent control air conditioning system controls temperature and humidity separately, which can solve the problems such as energy waste, difficult control of humidity and air quality in traditional air conditioning system effectively. In this system, terminal heat exchange equipment runs in dry condition, heat transfer temperature difference and heat transfer decreases. To eliminate indoor excess heat, usually need to increase air volume or the equipment model, that will result in increase of operating cost or investment. Parallel flow heat exchanger is efficient and compact heat exchanger, which can improve heattransfer amount of the device effectively, so we maybe can use it in the terminal equipment of temperature and humidity independent control air conditioning system, to replace conventional heat exchanger.Firstly theoretically analyzed the difference of heat transfer and flow performance between parallel flow heat exchanger in dry condition and parallel flow evaporator, then researched heat transfer and flow performance of louver fin in air side of parallel flow heat exchanger by numerical simulation, analyzed the influence of fin height,fin pitch,fin width,louver pitch,louver angle and louver height on the air side heat transfer coefficient and pressure drop of heat exchanger in dry condition, raised structural parameters that applied to parallel flow heat exchanger in dry condition.According to numerical simulation analysis results, optimal designed and manufactured two different parallel flow heat exchangers. Test this two heat exchangers by experiment in dry condition, compared their heat transfer and resistance characteristic. Heat transfer amount, heat exchange coefficient, resistance changes of two parallel flow heat exchangers were tested under the different air speed and water flow. According to the tested experimental data, in the same range of various air speed and water flow, heat transfer amount of optimized parallel flow heat exchanger2in dry condition increased4%than original basic heat exchanger1, airside heat exchange coefficient of heat exchanger1is94.9-140.1W/m2·K, total heat exchange coefficient is86.8-123.2W/m2·K, airside heat exchange coefficient of heat exchanger2is101.1-153.5W/m2·K, total heat exchange coefficient is92.3-134.3W/m2·K, average increased8%. Airside pressure drop of heat exchanger2is lower than heat exchanger1, and waterside pressure drop is larger, but both airside and waterside integrate performance coefficient of optimized heat exchanger2is higher than heat exchanger1. It shows that overall performance of heat exchanger can be effectively raised by adjusting its structural parameters.The study of this text has important guiding significance for the use of parallel flow heat exchanger in the temperature and humidity independent control air conditioning system and its design and optimization.