Water chilling method and apparatus for the same

Abstract

A water chilling apparatus comprising a plurality of chilling modules each having a refrigerating cycle mainly composed of a compressor, a condensor, an evaporator and an expansion mechanism, and a control module having a water pump for feeding, to an object to be chilled, chilling water cooled down by the evaporator of each chilling module, a detector for detecting a temperature of the chilling water and a water temperature controller. A chilling ability of each chilling module in response to a variable frequency is kept at substantially the same level. A capacity of the compressor of each chilling module is variably controlled in a range between an upper limit capacity and a lower limit capacity. The water temperature controller is used to calculate a whole necessary capacity value needed in the compressors of all the chilling modules as a function as a deviation between a set value of the chilling water temperature and a chilling water temperature detected by the detector. The number of the operated chilling modules is controlled in response to the whole necessary capacity value and the upper and lower capacities of each of the chilling modules. The capacity of the compressor of each of the cooling modules is controlled so as to have a capacity value obtained by equally distributing the calculated whole necessary capacity value by the number of the operated chilling modules.