Research Of Water System Control For Energy Saving In Central Air-Conditioning System

With the world energy shortage growth, energy issues have become an increasingly pressing issue. According to related statistics, central air-conditioning energy consumption accounts for about 50% of the total building energy consumption, the energy consumption of water system accounts for around 60% of the central air-conditioning energy consumption. The design capacity of the central air conditioning system is the maximum cooling load, but most of the time the system is running at part load. The majority time of central air conditioning water systems are working at constant flow mode, when the load changes, the pump is always running at full speed under design conditions, the water flow can not follow the actual load demand, resulting in huge energy wasted. Variable flow is based on the actual change requirements for water flow in air-conditioning load which means the system can track the actual load.In this article, through the analysis of working principle of central air conditioning system, water system, we proposed that frequency control for pumps can meet the demand for cooling capacity. The system will provide corresponding cooling capacity, to meet the system requirements to reduce energy consumption at the maximum. Design the scheme for three subsystem of the central air conditioning system.Cooling water system of central air conditioning is a typical non-linear, time-varying, multi-variable complex system, which is difficult to establish the accurate mathematical model, the conventional control method based on the precise mathematical model is difficult to obtain satisfactory control effect, because fuzzy control do not need precise mathematical model of controlled object, for all kinds of interference and noise have a strong suppression. This paper proposed a method based on fuzzy reasoning tuning PID controller parameters, to design appropriate adaptive fuzzy PID controller. Simulation studies show that the adaptive fuzzy self-tuning PID controller has both the advantages of high precision conventional PID, and also has quick, strong adaptability and characteristics of the fuzzy control. The result has a good dynamic and steady state characteristics.Finally, to renovation the water system of central air conditioning systems using in production plant in a company in Hefei. Modbus protocol can provide reliable communications between the Advantech PAC and the inverter, reducing the electromagnetic interference. When the production conditions are met, we can see that the energy saving achieved good results.