Performance evaluation device for variable-speed centrifugal chiller
An object is to sequentially calculate planned COPs. Provided is a performance evaluation device for a variable-speed centrifugal chiller that includes a data acquisition unit that acquires operating data of the variable-speed centrifugal chiller as input data; a storage unit that stores a first arithmetic equation derived on the basis of mechanical characteristics of the chiller and used for calculating a relative load factor that relatively expresses a relationship between a current load factor at a current coolant inlet temperature and a predetermined load factor at a predetermined coolant inlet temperature set as a reference operating point, a second arithmetic equation that expresses a relationship between the relative load factor and a correction coefficient, and a third arithmetic equation used for calculating a planned COP by using the correction coefficient to correct a COP calculation equation derived from a reverse Carnot cycle; and an arithmetic unit that calculates the planned COP under current operating conditions by using the operating data acquired by the data acquisition unit in the first, second, and third arithmetic equations stored in the storage unit.
1. A performance evaluation device for a variable-speed centrifugal chiller, comprising:
a data acquisition unit that acquires operating data of the variable-speed centrifugal chiller as input data;
a storage unit that stores a first arithmetic equation derived on the basis of mechanical characteristics of the chiller and used for calculating a relative load factor that relatively expresses a relationship between a current load factor at a current coolant inlet temperature and a predetermined load factor at a predetermined coolant inlet temperature set as a reference operating point, a second arithmetic equation that expresses a relationship between the relative load factor and a correction coefficient, and a third arithmetic equation used for calculating a planned COP by using the correction coefficient to correct a COP calculation equation derived from a reverse Carnot cycle; and
an arithmetic unit that calculates the planned COP at a current operating point by using the operating data acquired by the data acquisition unit in the first, second, and third arithmetic equations stored in the storage unit,
wherein the correction coefficient obtained in the second arithmetic equation is a correction coefficient for making characteristics of an actual ideal COP under ideal conditions and calculated using the COP calculation equation included in the third arithmetic equation closer to actual COP characteristics.
2. The performance evaluation device for a variable-speed centrifugal chiller according to claim 1 , wherein the first arithmetic equation is an arithmetic equation for deriving the relative load factor from a relative-design airflow coefficient determined by a compressor adiabatic head value.
3. The performance evaluation device for a variable-speed centrifugal chiller according to claim 1 , wherein the third arithmetic equation includes a term for compensating for heat loss occurring during heat exchange in the variable-speed centrifugal chiller.
4. The performance evaluation device for a variable-speed centrifugal chiller according to claim 1 , wherein when the variable-speed centrifugal chiller is operated at a design point of rated specifications different from a design point of rated specifications assumed for the first arithmetic equation, the second arithmetic equation, and the third arithmetic equation, an offset term for compensating for an error with respect to the design point of rated specifications assumed for the first arithmetic equation, the second arithmetic equation, and the third arithmetic equation is incorporated into the first arithmetic equation.
5. The performance evaluation device for a variable-speed centrifugal chiller according to claim 1 , comprising a display section that displays the planned COP calculated by the arithmetic unit together with a current actual COP.
6. A variable-speed centrifugal chiller in which the performance evaluation device for a variable-speed centrifugal chiller according to claim 1 is mounted on a control board.