An investigation on the efficient reverse cycle defrosting strategy for microchannel heat exchanger heat pump system

Xiong, Tong; Liu, Guoqiang; Wang, Siyuan; Yan, Gang; Yu, Jianlin

doi:10.1016/j.jobe.2023.106537

Cited by 3 publications

(2 citation statements)

References 22 publications

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“…Air source heat pump (ASHP) units have been used for space heating and refrigeration worldwide 1,2 because of their simple structure, convenient installation, high efficiency, energy conservation, and environmental protection. [3][4][5][6] However, for a space heating ASHP unit, frosting on its outdoor coil remained a key problem to be solved, 7 affects the heating efficiency. Especially when the air temperature is À7 to 5.5°C and the relative humidity is greater than 60%, frost is more serious on the surfaces of ASHP outdoor heat exchangers.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, to improve the heating performance of ASHPs and improve indoor thermal comfort, research on effective defrosting and frost suppression technology is vital. 17,18 Defrosting methods are available, including reverse cycle defrosting (RCD), 4,[19][20][21] hot gas bypass defrosting, 22,23 electric heating defrosting, [24][25][26] compressor shutdown defrosting, 27,28 and ultrasonic vibration defrosting. 29 Currently, RCD is the mainstream defrosting method; it can achieve rapid defrosting and significantly improve the heating capacity and coefficient of performance (COP) of ASHPs.…”

Section: Introductionmentioning

confidence: 99%

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Frost suppression performance of an air source heat pump using sensible heat from indoor air to preheat outdoor air

Wei

Wang

Feng

et al. 2023

Building Services Engineering Research and Technology

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Frost forms on the surfaces of air source heat pump (ASHP) outdoor heat exchangers under heating mode in winter, when the surface temperature of the heat exchanger is lower than both 0°C and the ambient dew point temperature. This can reduce the coefficient of performance (COP) and heating capacity of the ASHP unit. A novel ASHP was examined using two rooms with the same size, orientation, and structure. To test the frost suppression performance of the novel system, two ASHPs of the same size and specifications, but one including a sensible-heat preheating device, were placed in the test platform rooms. By comparing and analyzing field-measured parameters such as COP, heat loss, and frost weight of the two ASHP units, the frost suppression performance of the novel ASHP was evaluated in severe, moderate, and mild frost areas. The results show that when the air conditions were −3.9°C and 98.7% in the moderate frost area and 3.2°C and 96.7% in the severe frost area, the novel ASHP showed significantly improved performance. The frost formation time increased from 25 min to 38.5 min, frost-defrost heat loss decreased by 31.6%–43.7%, frost weight decreased 11.8%–17.4%, and COP increased 7.4%–13.1% compared with those of the conventional ASHP. In the low temperature and mild frost area, when the air temperature was −11.8°C and the relative humidity was 88.8%, the frost suppression effect of the novel ASHP was unapparent. Affected by the climate, the operation performance of ASHP will be different. Different ASHP can be used to adapt to the weather in different regions. The novel ASHP can significantly suppress frost and improve the heating performance of the unit in the mild climate and frost serious areas.

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