Application of a Fuzzy State Estimation Method to Defrosting Control of Open Showcase

Abstract

We have developed a fuzzy estimation method of frosting state on open showcase's evaporator. The contant interval control, which period is satisfied in severe circumstance such as midsummer, is generally used for the defrosting control of open showcase. But it have many problems such as a decrease of goods freshness resulted from an increase of air temperature in showcase and an increase of runing cost, because amount of frost depends on outer conditions.Therefore, we had been experimentally investigated the frosting characteristic on evaporator, and obtained that amount of frost is mainly detected by the difference between air temperature in inner duct and air temperature at outside of evaporator. And we have been investigated the abnormal characteristic resulted from unequal frosting. After analyzing their experimental data, fuzzy estimation rules have been designed.And we confirmed that the proposed method can distinguish the frosting state between normal and abnormal, and the change of frost quality by field test.