Control strategy for energy saving of refrigerating station systems in public buildings

Abstract

In this work, a global energy saving optimal control strategy is proposed to address the high energy consumption of chilled water pumps caused by the small temperature difference between supply and return water, and the low efficiency of the chillers. The developed control strategy consists of two parts: the group control scheme and an optimal controller for variable water temperature/volume control. The group control scheme coordinates each chiller's operating time based on its running time and the chiller load rate. The optimal controller regulates the chilled water pump frequency according to the chilled water temperature difference and the valve opening at important terminal air conditioning units, and calculates the chilled water supply temperature under optimal comprehensive energy consumption of chillers and pumps. The proposed control strategy is easy to be embedded into the existing control systems of refrigerating stations. This scheme is then applied to the air conditioning system of a large public building in Beijing, China. Experimental results show that the proposed strategy can save up to 63% of energy consumption from the chilled water pumps and 6% from the chillers compared to the original control scheme.