Research And Optimization Of VAV Air-conditioning Water System

Water systerm is a major part of the Air Conditioning Systerm, the energy conservation of variable water volume system under Part-load operating conditions is always attended by the relevant academics as the complexity of Hydraulie pipe network.The energy-saving reaserch of variable water volume aims to find a more reasonable method of optimal control,which makes the cooling capacity supplied by chiller plant and water pump matchs to the actual demand of building.Moreover,the chiller plant's strat-stop and the rotate speed of water pump are controlled to maks the whole air conditioning system consume the most minimum energye.This paper is based on the experimental research platform of the variable air volume (VAV) air conditioning system.A communication network,of which the control layer is made up by OMRON PLC and the information layer by Lab VIEW of NI company, is builded to ensure the information transmission's reliability and real-time from the device level to the information layer of the entire air conditioning control network communication system.By analyzing the energy-saving potential of water system distribution and the impact factor of system control energy-saving, the DMC-PID cascade control theory is proposed in this paper to control the supply air temperature at the end of the Water system,and the cascade control loops is Composed by the inner water flow control loop and the outer temperature control loop.This mothed could improve the water system's rate of response to the air-conditioned room load change and the anti-interference among those end of Water slips. Based on the above, the Chain Control is used between chilled plant and cooling loop to hold the supplied chilled water temperature Constant,then a synthesized method composed by chilled water valve opening control and the volume control is used to control the Variable Pump, to maks the pump run in similar operating point, and give full play to the potential savings in pump frequency. At the end of this paper some experiments are set up to prove the method is energy-saving.