Research On Variable Water Temperature Control Strategy Of Subway Station Air Conditioning System

The operation of ventilation and air conditioning systems in subway stations consumes large amounts of energy,and their energy-saving optimization can effectively reduce building energy consumption and help achieve the goal of "carbon neutrality and carbon peaking".Variable water temperature control is an important method for energy-saving control of ventilation and air conditioning systems in metro stations,but there is a lack of mechanistic research on variable water temperature control in existing studies.This paper relies on an air conditioning system of a metro station in Guangzhou,and studies the chilled water variable water temperature control strategy based on TRNSYS software.Combined with the basic situation of the project,a building model of the metro station is built in the TRNBUILD application and the time-by-time cooling load of the metro station is calculated for the whole cooling season,and the simulation results are analyzed to match the actual situation,which verifies the accuracy of the building model.The simulation results were found to be consistent with the actual situation,and the accuracy of the building model was verified.Further analysis of the chilled water supply temperature on the end equipment,according to the load rate to develop a set of segmented variable water temperature control strategy,simulation results show that the water system energy saving rate of 19.47%,but through the end of the verification found that this control strategy can not take into account the dehumidification needs.In order to meet the needs of dehumidification and heat transfer in the hot zone at the same time,it is necessary to establish an accurate,time-tested equipment characteristics model.Therefore,a mathematical model of the end equipment characteristics was constructed in the form of a cooling coil characteristic equation,combining the operating results of different end equipment under different operating conditions in the TRNSYS simulation platform.Based on this model,we developed the optimal chilled water supply temperature calculation component Type327,built a constant flow rate and variable water temperature control system,and proposed a "global" control strategy and an "economic" control strategy,and the energy saving rate of the water system was 3.1% and 14.77% respectively after the simulation.14.77%,"economic" control strategy does not guarantee the rate of 0.64%,taking into account the energy saving rate and the rate of non-guarantee,"economic" control strategy is better.In order to further study the variable water temperature control strategy,the variable water volume and constant water temperature air conditioning system was built,and the energy saving rate of the water system was 20.26% compared with the basic air conditioning system model.After the simulation,the energy saving rate of the water system was 10% and18.8% respectively compared with the variable water temperature air conditioning system.The "economic" control strategy does not guarantee the rate of 2.76%,comprehensive consideration of the "economic" control strategy is better.