Frost suppression performance and degradation mitigation strategy of superhydrophobic air source heat pump

The superhydrophobic coating exhibits excellent frosting suppression performance on a single surface or a full-scale heat exchanger. However, its suppression performance when used in air source heat pumps (ASHPs) is still unclear, owing to the more complex factors. To promote its application in ASHPs, the superhydrophobic coating with good durability was fabricated, and used to manufacture the superhydrophobic ASHP. Its space heating and frosting performance under different frosting conditions were investigated. Then, for its frost suppression performance degradation problem during continuous frosting-defrosting process, the reasons were analyzed and a solution was proposed. Experimental results showed that the frost suppression performance of superhydrophobic ASHP varies significantly under different frosting condition. Its frost suppression performance was excellent at the 2/1 °C condition, while failed at the −3/-4 °C condition. At 2/1 °C condition, its heating duration, average heating capacity and coefficient of performance were increased by 16.00 %, 10.91 %, and 6.35 %, compared to conventional hydrophilic ASHP. During the continue frosting-defrosting cycles, the frost suppression performance of the superhydrophobic ASHP degraded gradually, owing to the fan blade and fan shroud icing. By adopting the proposed control strategy combining fan reverse operation and electric heating film operation, the frost suppression performance degradation problem was addressed effectively.