| The ventilation and air-conditioning system of subway stations has high energy consumption,and it is of great practical significance to control and adjust the energy-saving air-conditioning system.This paper takes the ventilation and air conditioning system of a subway station in Zhengzhou as the object,and adopts various energy-saving control strategies for the station’s chilled water system and cooling water system to conduct a simulation study based on the TRNSYS platform.Firstly,combined with the project data,use TRNBUILD to establish the station building model and complete the hourly cooling load simulation calculation of the building during the cooling season,compared with the design calculation value,there is a 2% error in the simulation results,and the simulation results are more accurate.Combined with the selection data and mathematical modeling of the air-conditioning system equipment,the basic model of the air-conditioning water system is established by using TRNSYS,which lays the foundation for the subsequent research on energy-saving control strategies.Most of the actual air-conditioning transmission and distribution systems have the phenomenon of "large flow and small temperature difference".Compared with constant pressure control,the use of constant temperature difference strategy can effectively solve the problem of large energy consumption in transmission and distribution caused by "large flow and small temperature difference".However,this method cannot guarantee sufficient flow through the terminal equipment;in addition,this method does not consider the influence of the energy consumption increase of the chiller caused by the reduction of the transmission and distribution flow.In order to improve the defects of the existing constant temperature difference method,this paper proposes a constant temperature difference correction strategy based on comprehensive energy consumption.This strategy is based on the premise of meeting the terminal cooling demand,and aims to reduce the comprehensive energy consumption of pumps and units.By developing the variable frequency pump module Type220 and the pump + unit integrated control calculation module Type275,the optimization calculation of the comprehensive energy consumption of the pump and the unit and the simulation of the air-conditioning water system are completed,the energy saving rate of the system after adopting the correction strategy is 18.5%.In order to achieve the lowest overall energy consumption of the air conditioning system under different load conditions,an improved constant temperature difference control strategy and an improved large temperature difference control strategy were studied for the chilled water system,the effects on the energy consumption of the system when the temperature difference of the chilled water is constant,the water supply temperature is 7-12 °C,and the temperature of the water supply are unchanged,and the temperature difference is 5-10 °C are respectively studied.Through the study of these two control strategies,for the air-conditioning system of this station,the conversion conditions for the joint regulation of the two are as follows: when the load rate is less than or equal to 40%,the strategy of constant temperature difference and variable water supply temperature is more energy-saving;when the load rate is greater than 50%,it is more suitable to adopt the improved control strategy based on the large temperature difference.The energy consumption of the cooling water system is reduced by adopting the strategy of frequency conversion of cooling water pump combined with frequency conversion of cooling tower fan,and PID is used to control the outlet water temperature of cooling tower to realize fan frequency conversion,the system energy saving rate is 15.2% under this strategy.In order to reduce the overall energy consumption of the air-conditioning system,the integrated energy-saving control scheme of Fengshui linkage is adopted,focusing on the theoretical and simulation research of the priority control water valve strategy,the overall energy consumption of the system is simulated and analyzed by adopting the method of real-time fine adjustment on the water side and three-step stepped coarse adjustment on the wind side,it is concluded that the overall energy saving rate of the air-conditioning system under the priority control water valve strategy is as high as 54.6%. |
