A Controller Algorithm (ILC) for the Variable Differential Pressure Control of Freezing Water in a Central Air Conditioning System.

In actual operation, due to the change of many factors, the central air conditioning system runs at non-designed working conditions in most of the time. Usually, it works under partial load, cannot meet the maximum load, causes great waste of energy. This paper proposes an Iterative Learning Controller algorithm (ILC) for the air conditioning water system, deal with the variable frequency control for the secondary pump. Optimization settings of water pressure differential value are given according to customer demand and based on the water valve features, thus make water valve in the chilled system having the largest opening as far as possible to provide the required minimum water differential pressure. By this way not only good control effects can be obtained, but also the energy consumption of pump delivery can be reduced.