AN ARRANGEMENT FOR THE OPTIMIZED CONTROL OF CHILLED WATER TEMPERATURE

摘要

In an arrangement for and method of controlling optimum chilled water temperature supplied to a process (5, 6) by a pump (14), the water being chilled by coolant in a coolant cycle (20) having a compressor (12) and a load valve (16), first and second sensors (22, 23) are used for sensing chilled water supply and return temperatures to and from the process. A value is obtained for the amount of work done by the pump (14) and the compressor (12) and that value, as well as the supply and return temperature values, is supplied to a supervisory control unit (30). The supervisory control unit (30) generates a reference temperature (Tref) which is a function of the supply temperature (Tsup) but which is either above or below the supply temperature depending on a ratio between the difference in work and a change in the difference between the supply and return temperatures. When the ratio is about zero this indicates that the difference between the supply and return temperature is at an optimum and the reference temperature (Tref) is the same as the supply temperature. When the ratio is negative, the reference temperature (Tref) is below the supply temperature and when the ratio is positiove the reference temperature is above the supply temperature. The reference temperature is used in a temperature control unit (50) which is connected to the load valve (16) for adjusting the setting of the valve according to a load demand signal which is chosen to be either the reference temperature if that is less or a demand value which depends on the amount of demand necessary for the process.