Effect of micro-nano structure on anti-frost and defrost performance of the superhydrophobic fin surfaces

Abstract

In order to study the effect of nanostructures on micro-nano structures on the frost suppression and defrosting performance of the superhydrophobic fin surface of the heat pump, a simple spray method was used to prepare the surfaces with the same static contact angle and rolling angle but different micro-nano structures. The research shows that the frost inhibition ability of superhydrophobic surface can be effectively improved with the increase of the density of nanostructures. In the condensation process, compared with the surface of micro-nano structure with low density nanostructures, the condensed droplets on the surface of high-density nanostructures have the characteristics of high renewal rate, small average size and low coverage. When condensing for 32 min, the number of condensation droplets merging, bouncing and sliding on the surface of nanostructure is 47.5% higher than that on the surface of micro-nano structure, and the area coverage of droplets is 25.46% lower than that on the surface of micro-nano structure. In the frosting experiment, superhydrophobic surface with the micro-nano structure lost its anti-frosting performance due to the Wenzel-state of condensate droplets, and the frost coverage rate reached 100% within 5 min. However, the frost coverage rate of the nanostructured surface only reached 4.6% in 10 min and reached full coverage in 95 min. It can be seen that the condensate droplet behaviors and frost suppression performance of the superhydrophobic surface are more sensitive to the surface nanostructure. However, the defrosting process is not sensitive enough to the nanostructures of the superhydrophobic surface. This standard provides the idea for the simple preparation of anti-frost superhydrophobic surface on the air-source heat pump fins.