Turbo chiller, heat source system, and methods for controlling them

摘要

There is provided a turbo chiller that can be operated at high efficiency within an adequate chilling capacity range even when the cooling water temperature changes during the operation. The adequate chilling capacity range is obtained by using a flow coefficient and a pressure coefficient at a specific operating point of a 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.