Refrigeration – Automatic control – Preventing – removing or handling atmospheric condensate
Patent
1989-07-26
1991-02-19
Tanner, Harry B.
Refrigeration
Automatic control
Preventing, removing or handling atmospheric condensate
62156, 62158, 62234, F25D 2106
Patent
active
049932330
ABSTRACT:
A demand defrost controller employs temperature measurements taken at the outlet of the discharge air curtain and the inlet of the air return to determine the need for defrost. If the difference between these temperature measurements exceeds a set point for a predetermined sustained period of time and a minimum amount of time has elapsed since the last defrost of the case, defrost is initiated. Regardless of the value of the temperature difference, defrost is initiated if elapsed time since the last defrost exceeds a specified maximum time between defrosts for the case. Defrost can be terminated on the basis of time and/or temperature. The demand defrost controller can also control display case temperature and can be applied to independently control multiple display case circuits.
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Demand Defrost Control CR70A, Honeywell 60-2070-5, pp. 1-13, 1974.
CEC KT33, Cooling Energy Control Limited, Wimbledon, London, pp. 1-3, (no date).
Frostec, Esswood Corporation, Cincinnati, Ohio, pp. 1-4, 1987.
Borton David N.
Walker David H.
Power Kinetics, Inc.
Tanner Harry B.
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