Study On Variable Static Pressure Setpoint Control Method And Outdoor Air Volume Guarantee In Variable Air Volume Air-conditioning System

Heating, ventilation and air conditioning system is responsible for approximately 50% consumption from total building energy consumption in large public buildings, hence, the air conditioning system is the main object of building energy saving. Due to the advantages of better energy saving effect, flexible configuration and easy extension, variable air volum(VAV) air conditioning system which could achieve full-control of thermal-moisture environment and indoor air quality of buildings has been widely used in large public buildings.Personnel amount and operating status of equipments of air conditioned zones are changing in multi-zone VAV air conditioning system, therefore, the air conditioning load and demand of outdoor air are different, which could be regard as a strong coupling system composed of thermal-moisture environment control and indoor air quality control. And in actual operatin process, problems of VAV air conditioning system mainly embody in two aspects. Firstly, control effect on the thermal-moisture environment is not as good as expected, and performance of energy saving effect is poor. Secondly, the air conditioned zones are lacking of outdoor air in most of time, which results the poor indoor air quality. Therefore, the optimization of air supply control algorithm and outdoor air control strategy is basic way to realize a good indoor environment and reduce energy consumption. Therefore, the main object of this research is the VAV air conditioning system with the purpose of realizing good indoor environment and indoor air quality. The resrarch of this paper is summarized as follows:Firstly, the integrated control experimental system for VAV air conditioning system is built. During this period, optimization design of thermo-system and HVAC system, debugging of control circuit and calibration of realted equipments are conducted. And network architecture of intelligent management system is put forward based on internet of building energy system (iBES).Secondly, this paper analyses the existing control methods of static pressure for VAV system, and provides a novel static pressure reset algorithm based on valve position of maximum valve position terminal. And tests are performed with the fixed static pressure, static pressure reset method in a fixed step value and the novel static pressure reset algorithm in the integrated control experimental system for VAV air conditioning system. Experimental results show that the proposed method has better control performance and temperature control effect, and a minimum of 4.94% energy saving is achieved compared with other methods.Thirdly, this paper analyses the existing control strategy of outdoor air for VAV system, and the total outdoor air volume, the main influence factors and distribution of outdoor air in air-conditioned zones are studied. On the basis above, performs tests with the variable outdoor air ratio to study the control effect of indoor air quality in the integrated control experimental system for VAV air conditioning system, and control strategy of variable outdoor air ratio based on MaxY(MaxY-V) and variable outdoor air ratio based on MSE(MSE-V) are compared. Experimental results show that energy consumption of MSE-V control strategy is 6.76% lower than MaxY-V control strategy with the same indoor air quality.Fourthly, the traditional VAV air conditioning system has problems of uneven distribution of outdoor air and high energy consumption of oudoor air form the above research. Hence, dedicated outdoor air system(DOAS) is introduced to VAV air conditioning system. And tests are performed between traditional VAV air conditioning system and the proposed system defined as VAV-DOAS air conditioning system, and energy consumption and economy are analysed. Experimental results show that 14.91% energy saving of VAV-DOAS air conditioning system is achieved with the same control effect of indoor temperature and indoor CO2 concentration. In addition, when the operating life of air conditioning system is more than 12 years, the VAV-DOAS air conditioning system is economically feasible. Intelligent control terminal for VAV air conditioning system is developed, which could achive all control algorithms involved in this research and the intelligent control terminal would provide a hardware foundation for future studies.