Experimental analysis on frosting characteristic of SK-type finned refrigerating heat exchanger with large-diameter circular holes

• The large holes of SK-type induced the generation of turbulence flow.
• The refrigeration capacity and COP of SK-type exceeds that of plane one.
• The SK-type fin-and-tube heat exchanger is a new kind of heat transfer equipment.
• The defrost interval should not exceed 2 h under frost conditions.

This paper presents the construction of both a plane fin-and-tube heat exchanger and a SK-type fin-and-tube heat exchanger. Based on plane fin-and-tube heat exchanger, comparative industrial prototype experiments of SK-type fin-and-tube heat exchanger energy efficiency performance were carried out in the artificial climate chamber. Test results confirmed several findings: when the amount of the refrigerant charged is the same and face velocity u = 3.75 m s−1, SK-type fin-and-tube heat exchanger refrigeration capacity increases by an average of 9.13%; energy consumption reduces by an average of 11.25%, coefficient of performance (COP) of heat exchanger increases by an average of 22.65% with continuous operation during the first 2 h. Also, when the operation time exceeds 2 h, the COP of both types of heat exchangers are both less than 0.6, illustrating that under frost conditions, the defrost interval should not be too long, otherwise energy consumption may sharply spike.