Patent ID: 6629422
Filing Date: 2003-10-07
Classification: A47F,F25D

Abstract:
For a series of refrigerated display cases each having an evaporator coil and operated in a refrigeration mode and a defrost mode, wherein each refrigerated display case operates in a refrigeration mode and a defrost mode independent of the refrigeration modes and defrost modes of the other display cases in the series, a method for controlling the operation of the series of refrigerated display cases to sequentially defrost the evaporator coils of the refrigerated display cases, the method comprising steps of:(a) starting a normal refrigeration mode for all of the display cases in the series of refrigerated display cases and setting a refrigeration time equal to zero wherein, during the refrigeration mode, each display case in the series of refrigerated display cases is operating a refrigeration mode; (b) monitoring the refrigeration time elapsed from the start of the refrigeration mode; (c) when the refrigeration time elapsed equals an activation time, starting a defrost mode wherein, during the defrost mode, the following steps are performed: (c1) for a first refrigerated display case, starting a defrost mode; (c2) for the first refrigerated display case, terminating the defrost mode based on a selected one of a defrost time criterion or a defrost temperature criterion; (c3) for the first refrigerated display case, restarting the refrigeration mode; and (c4) repeating the steps (c1) through (c3) for each successive refrigerated display case in the series of refrigerated display cases, such that no more than one refrigerated display case is in a defrost mode at any one time; and (d) terminating the defrost mode, setting the refrigeration time equal to zero and returning to the normal refrigeration mode at step (b).