Abstract: In the design of outdoor finned tube heat exchangers, the traditional approach is to incorporate subcooling pipes at the bottom to suppress frosting. However, this method has certain limitations because the refrigerant temperature inside the subcooling pipes is usually higher than the ambient temperature, which not only leads to the waste of heat exchanger area but also increases additional design costs. To address this issue, researchers have designed a heat exchanger process without subcooling pipes, and by introducing superheated refrigerant into the bottom of the heat exchanger, they have achieved the dual purpose of full flow path heat transfer and frost suppression. Experimental research analysis indicates that the performance of heat exchangers using the subcooling pipe-free scheme has been enhanced. Specifically, compared to conventional heat exchangers, the heating duration of this design's unit is extended by about 15%, the heating capacity is increased by about 8.2%, the heating energy efficiency is improved by about 5.4%. These improvements contribute to the development of more efficient and comfortable air conditioners in the heating-oriented field.

Key words: Eliminate subcooling pipes, Suppressing frosting, Full-flow heat exchange