| 摘要 |
A commercial refrigerated display case, of the type in which an air curtain is directed across an upwardly opening product display space, utilizes ambient air for defrost purposes. A discharge sill extending along the back of the case, above the discharge grille through which air is directed to form the air curtain, is hollowly formed to provide a defrost air chamber. Within the chamber defrost air fans are mounted and are normally off during the refrigeration cycle of the display case. During defrost, the air circulating fan continues in operation although the evaporator coil is no longer in a refrigeration mode. At the same time the defrost fan goes into operation, and draws off part of the air circulated through the discharge grille by the main fan, and exhausts it to ambient through the discharge sill. A weak air curtain is still maintained across the access opening of the display case. Drawing off part of the air through the discharge grille, while continuing operation of the main fan, causes at least a substantial part of the air drawn through the return opening to be obtained from the surrounding ambient, so as to swiftly defrost the evaporator.
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