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US 4,285,204 AGranted
Defrosting problem areas of refrigerated display cases
AssigneeEmhart Industries, Inc.
InventorJohn H. Vana
Life of this patent
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AssigneeEmhart Industries, Inc.
InventorJohn H. Vana
Estimating the term…
Defrost of a refrigerated display case, especially those cases in which refrigerated air curtains are directed across open front or open top areas, is improved by reversing the direction of the air circulating fans during a predetermined portion of the time during which the case is in a hot gas defrost mode. In a preferred example, the evaporator fan motors are reversed following the initiation of a hot gas defrost cycle, at a time during the cycle when air warmed by the defrosting evaporator coil becomes available. A thermally actuated switch means effects the reversal at the appropriate time, so that areas of the refrigerated display case that would normally be the last to receive the benefits of the warmed air, in particular the return air flue and tank drain, become the first to be subjected to the warming effect thereof.
In a refrigerated display case having a product display area, an air passage extending about the display area and formed with an air return flue, an air discharge duct, and a plenum providing communication between the flue and duct, an evaporator in the plenum adapted to be defrosted by hot gas flowing therethrough, at least one air circulating fan in the passage, the air circulated within the passage normally flowing, when the case is in a refrigeration mode in a first direction in which it flows through the evaporator in heat exchanging relation thereto, then through the discharge duct and thereafter back to the evaporator through the return air flue, the improvement that comprises a system of combining hot gas defrost of the evaporator coil with air defrost of at least the return air flue, said system including means for reversing the direction of air circulated within the passage at a time during the hot gas defrost cycle when the evaporator is transferring heat to air flowing therethrough, for defrosting of the air return flue by circulating therethrough, directly from the plenum, reversely flowing air that has been warmed by the transfer thereto of heat produced by hot gas defrost of the evaporator.
In a refrigerated display case having a product display area, an air passage extending about the display area and formed with an air return flue, an air discharge duct, and a plenum providing communication between the flue and duct, an evaporator in the plenum adapted to be defrosted by hot gas flowing therethrough, and a drain disposed in the plenum between the evaporator and the air return flue, the air circulating within the passage normally flowing, when the case is in a refrigeration mode, in a first direction in which it flows through the evaporator in heat exchanging relation thereto, then through the discharge duct and thereafter back to the evaporator through the return air flue, the improvement that comprises a system of combining hot gas defrost of the evaporator coil with air defrost of the return air flue and the drain, said system including means for reversing the direction of air circulated within the passage at a time during the hot gas defrost cycle when the evaporator is transferring heat to air flowing therethrough, for defrosting of the flue and the drain by impingement thereon, directly from the plenum, of reversely flowing air that has been warmed by the transfer thereto of heat produced by hot gas defrost of the evaporator.
The method of defrosting a refrigerated display case that comprises the steps of circulating hot gas through an evaporator coil of said case while maintaining operation of an air circulating fan to circulate air through the coil in the direction in which the air is circulated during normal refrigeration modes of the case;
Dependencies are inferred from the claim text.