Addressing the issue of “erroneous defrosting” in the defrosting condition of the evaporator

a novel intelligent defrosting control strategy based on the principle of parallel-plate capacitor is proposed

a mathematical model of parallel-plate capacitor is established in the process of frosting and defrosting of the evaporator

and the theoretical analysis of the proportion of air/frost/water intermediate medium on the capacitance value is conducted. The capacitance value shows a slow linear growth during the frosting process

while it rises first and then falls in the defrosting process. This paper takes the cold store evaporator as the research object

constructs the capacitance defrosting control system

and the experimental results are consistent with the theoretical analysis of the change trend of capacitance value. The results show that 32.0 pF and 19.0 pF can be used as the start-stop point of intelligent defrosting control respectively. The fluctuation range of the central temperature in the cold store is reduced by 12.0 ℃

the defrosting cycle time is shortened by about 4 min

the defrosting efficiency increased by about 22 %

the defrosting power consumption is reduced by 36.74%

and the total electricity consumption of the refrigeration system is reduced by 19.8 %. This study provides an effective approach for efficient and safe defrosting in refrigerating system.