Article ID Journal Published Year Pages File Type
6685708 Applied Energy 2015 13 Pages PDF
Abstract
When an air-source heat pump (ASHP) was operated in heating mode under certain ambient conditions, frost always accumulated on the fin surface of its outdoor coil. Frosting may increase the energy consumption and deteriorate the performance of the ASHP, and hence, periodic defrosting is necessary. In this study, a new defrosting method using intermittent ultrasonic vibration was investigated. First, the vibration attenuation characteristics of a double-row outdoor coil and the frost growth characteristics under different ambient conditions were determined. Next, the average frost thickness with and without the application of intermittent ultrasonic vibration was calculated using MATLAB software. Finally, the decrease in defrosting energy consumption, the increase in heating capacity, and the increase in the coefficient of performance were analysed. The experimental results indicate that intermittent ultrasonic vibration could effectively remove the frost accumulated on the fin surface, and the effective defrosting area of an single ultrasonic transducer was 0.165 m2 for a double-row finned-tube evaporator on which an ultrasonic transducer with a rated power of 50 W and resonant frequency of 40 kHz was applied. The defrosting energy consumption of the ASHP unit with ultrasonic vibration was 3.14-5.46% lower than that without ultrasonic vibration, whereas the heating capacity increased by 2.2-9.03% and the COP increased by 6.51-15.33%. In addition, the thermal comfort of the indoor side was clearly improved.
Related Topics
Physical Sciences and Engineering Energy Energy Engineering and Power Technology
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