Experimental study on the regulation mechanism of the synergistic effect of microgrooves and surface structures on the condensation and frosting process under inter-fin restricted airflow

The frosting problem on the fins of air source heat pump heat exchangers under low-temperature and high-humidity environments restrict their efficient operation. Adding microgrooves on the surface of the fins to divert condensation droplets and increasing surface structure to induce nucleation is expected to regulate the spatial layout of condensation droplets and frost. This study established an experimental setup with a transparent acrylic channel to observe condensation and frosting of an individual fin under constrained air flow. It quantitatively investigated the spatial layout characteristics of condensed droplets and frost under different microgroove directions and surface structures, extracted key parameters, and qualitatively characterized frost spatial layout via surface gray level difference. The results show that forward microgrooves reduce droplet spatial layout non-uniformity by 14.3%, while reverse ones increase it by 17.4%. Arc-shaped surface structures have better flow adaptability. The coupling of microgrooves and surface structures achieves coordinated regulation, with forward microgrooves reducing concave surface frosting non-uniformity by up to 36.2%. These findings validate the effectiveness of microgrooves and surface structures in inducing condensation and frosting. This study provides a theoretical and quantitative basis for optimizing fin structures and alleviating frosting.