| 摘要 |
PROBLEM TO BE SOLVED: To suppress energy consumption and excessive heating of an evaporator by effectively sensing frosting of the evaporator and defrosting only for a necessary time. SOLUTION: The frosting detector for detecting a frosting state of an evaporator 1 for constituting a deep freezing circuit comprises an inlet gas temperature T1 detector 2 immediately before passing circulating cold air through the evaporator, an outlet gas temperature T2 detector 3 immediately after passing the cold air through the evaporator, and a controller 6 for sensing the frosting state from a temperature difference between an inlet gas temperature and an outlet gas temperature to defrost. In the case of passing the cold air through the evaporator, T1 and T2 are measured, a trend of approaching a temperature relation of T1>T2 to T1=T2 is captured to sense the frosting, and a signal is output to the exterior by the frost judging unit. During frosting, a slight air supply is conducted, an output of the heater or the like is controlled so that the relationship of T1=T2 may not become excess to T1<T2.
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