Patent ID: 8132421

Claim:
A turbo chiller operated within a predetermined adequate chilling capacity range, the turbo chiller comprising: a turbo compressor driven by an inverter in a manner that enables variable revolution speeds; a condenser that condenses refrigerant compressed by the turbo compressor; an expansion valve that expands the condensed refrigerant; and an evaporator that evaporates the expanded refrigerant to cool cooled water, wherein the adequate chilling capacity range is obtained by using a flow coefficient and a pressure coefficient at a specific operating point of the turbo compressor as well as a predetermined coefficient to determine an arithmetic expression representing the relationship between a head and a chilling capacity, using a chilling capacity that can lead to a substantially highest coefficient of performance at a single head to obtain the predetermined coefficient as an optimum coefficient, computing an adequate operation coefficient range having a predetermined range and including the optimum coefficient, and substituting the adequate operation coefficient range and a head at the time of operation into the arithmetic expression.