| 摘要 |
PROBLEM TO BE SOLVED: To save energy and prolong freshness of merchandise by activating a defrosting device at optimal timing suitable for daytime hours and at optimal timing suitable for nighttime hours. SOLUTION: Cooled temperatures at an evaporator and an inner duct in a show case 1, and an ambient temperature and an ambient humidity are detected by sensors 31, 32. Next, arithmetic sections 4, 5, 6, 12, 33, 34 calculate the difference between the detected values, the deviation of the values, and the variation of the values, etc., and further calculate the difference between a time period elapsed from a last defrosting operation and an average defrosting time period. A fuzzy inference section 7 executes a fuzzy inference, based on the calculated values, to thereby estimate the amount of frost formation on the evaporator. Further, the fuzzy inference section 7 separately determines optimal timing suitable for daytime hours and optimal timing suitable for nighttime hours, depending on the outside air conditions, whereby a defrosting starting signal is output.
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