Experimental investigation of frost retardation for superhydrophobic surface using a luminance meter

• This study investigated the phenomena of frost retardation.
• A novel experimental method using a luminance meter is introduced.
• This experimental method is able to define the frost stages quantitatively.
• The 10 different water contact angle were used to analyze the frost retardation.

We experimentally investigated the phenomena of frost retardation in terms of the heat exchanger fins with various water contact angles under normal air-source heat-pump operating conditions. We first introduced a new experimental method using a luminance meter, which measured the light intensity from the surface, and determined the phase-change time, for quantitatively defining the frost stages. The phenomena of frost retardation was analyzed for 10 samples with different water contact angles (75°–160°) at different refrigerant temperatures. When the refrigerant temperature was −10 °C or −12 °C, the effect of frost retardation increased remarkably with superhydrophobic surfaces. However, when the refrigerant temperature was −8 °C, the effect of superhydrophobicity diminished at water contact angles greater than 150°.