Dual setpoint control for an absorption chiller

摘要

A method of controlling the capacity of an absorption chiller by regulating the heat input to a generator in response to a selected one of two system variables. The first variable involves the measured chilled water temperature leaving the system evaporator and the second involves the calculated solution concentration that is being returned to the absorber. Data relating to each variable is sent to a selector where it is processed so that the data can be used to control the heat input to the generator. The temperature data is used to control the heat input during normal chiller operation, however, the selector changes over control to the concentrate related data when the solution concentration level approaches the solution crystallization limit.