Research On Central Air Conditioning Chilled Water System Control Strategy And Its Application For GLPI-Park

With the development of urbanization in our country, the proportion of building energy consumption keep rising, our country advocates to save the energy, the low carbon and environmental protection, to achieve the sustainable development, and paying more attention to the building energy conservation, in the end it promotes the development of the building energy saving technology. Central air conditioning system is the bulk of the building energy consumption, and a lot of energy consumption is due to the human mismanagement and the automation level is not so high, that causes unnecessary loss, therefore, each subsystem of the central air conditioning system and the control strategy of the research and how to integrate them in a building automation system, become a focus of attention. Central air conditioning chilled water system is a complex system which is typical nonlinear, time-varying and large inertia, the article combining with engineering example, the control strategy of the central air conditioning chilled water system is studied and applied in this paper and puts forward the optimization scheme of the chilled water system with the minimum resistance of a pump variable flow system.This paper first introduces the central air conditioning chilled water system, it elaborates the principle of central air conditioning system and the energy conservation evaluation indexes(COP, EER), and discusses the operation strategy of chilled water system and the control method of variable flow rate. Then in view of the chilled water pump variable flow control strategy of least resistance, the article analysis the feasibility of its application in practical engineering, and expounds the configuration requirements of the variable flow water system for equipments and the energy saving potential of variable pressure difference of least resistance control. In addition, the article also introduces the Johnson building automation system’s network structure, the composition of its software and hardware and the application platform, in order to be convenient later for construction of the central air conditioning system platform, and the compilation of control program.Finally, based on the Xi’an GLPI-Park project, by designing the experiment on the evaporator side of the cold machine to analysis the feasibility of the variable flow control in the chilled water pump system, the article points out that the cooler with the variable flow operation in a certain range does not affect the normal operation, and can reduce the energy consumption of the whole system. Using the Johnson control system as the building control platform, according to the actual situation make the chilled water pressure differential operation scheme of least resistance, and make Fan start-stop control program, Humidifier control program, Frozen water valve control program, Variable frequency pump, Bypass valve control program, Frozen water pump control and minimum resistance control program. At last, in this paper, the control of constant pressure difference and the minimum resistance control of variable pressure difference for primary pump variable flow system are compared, it is concluded that under the same conditions that meet the requirements of the user load, the energy saving of the control of variable pressure difference of the minimal resistance is significantly better than the control of constant pressure difference, and the lower the load rate, the more significant the energy saving effect is.