A Study Of The Control System Based On Field Bus For Heat Pump Air-Condition

Water Source Heat Pump Air-condition (WSHPA) is the equipment that can use the terrestrial heat and has the functions both saving-energy and protecting-environment. So people look with favor on WSHPA in the recent years. But the research work on WSHPA could not keep up with its engineering applications in our country.In this paper a new control precept based on field bus about WSHPA is presented. According to the refrigerating and heating output needed by buildings, adjusting the water source pump output makes the temperature of the WSHPA stable nearby set point. And this precept can be used in the water cycle system inside the buildings. The method of self-tuning PID is used in this system. In addition, applying LONWORKS technology in the control system for WSHPA makes the controller more intelligent and effective.According to the practical engineering applications, at least three problems can be solved or alleviated by this control method. Firstly, using this method the power of the feed pump or circulating pump can be conserved when the load of refrigerating and heating output turns low. Secondly, the less underground water needed when less load, the water needed to fill back into the ground can be reduced. Thirdly, because the switch frequency of compressor can be reduced, this method can prolong life of WSHPA.The task discussed in this paper is a part of the WSHPA system project of NCUT. The new controller based on LONWORKS technology can make the WSHPA system more effective. And the control method discussed in this paper can be used in this kind of system.