| Summary: | 碩士 === 國立臺北科技大學 === 能源與冷凍空調工程系碩士班 === 97 === While single stage air source heat pump water heater runs in conditions of low ambient temperature(-5~-25℃), it will face some problems. Such as: Compression ratio of the compressor will be oversized, the evaporator inlet quality will increase, and the discharge temperature of compressor will increase. Therefore, if air source heat pump water heater runs in conditions of low ambient temperature, it can overcome the above problem, and make the high efficiency. It’s important to development equipment. The objective of this study is, through theory simulation parametric analysis adjusting the intermediate pressure to change system performance for quasi-two stage air source heat pump water heater with economizer and R-404A in different operating condition. The results show that: quasi-two stage air source heat pump water heater can increase the coefficient of performance about 17% than single stage. The refrigerant using R-404A can increase the coefficient of performance about average 8% than R-22. In different operating condition(condensing pressure and the evaporation pressure), the system uses quasi-two stage air source heat pump water heater with economizer and R-404A, There will be a maximum value of the heating coefficient of performance and the coefficient of performance correspondence for optimum intermediate pressure. The optimum intermediate pressure occurs closely to the geometry of mean value condensing pressure and the evaporation pressure. The obtained result of this study equivalent to Cao(2009).
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