Research On Control Method Optimization Of Ventilation And Air Conditioning System

In recent years,urban rail transit has been developing rapidly in China due to its convenience,safety,punctuality,etc.As important parts of urban rail transit,a vast majority of subway stations are located underground,which requires the Ventilation and Air Conditioning system to maintain the stability of various index,such as the fresh air volume,the temperature and humidity,and the concentration of CO₂.Lately,its demand for energy conservation and emission reduction keeps increasing.Since the energy consumption of Ventilation and Air Conditioning system accounts for a large proportion of the total energy consumption,a reasonable operation method becomes the major strategy to reduce energy consumption.Based on the analysis of its components and characteristics,the parameter,mode and energy consumption of Ventilation and Air Conditioning system at subway stations are investigated;by deconstructing the energy consumption of low-voltage power distribution system,the air-conditioning system（general system）in public areas is taken as the focus of energy-saving work.According to the theoretical analysis and numerical calculation,the basic loads of Ventilation and Air Conditioning system are studied from various perspectives,such as equipment,heat transfer of exterior protection,personnel and fresh air;and it is quite clear that the personnel load and fresh air load are the most influential factors by comparison.Based on the on-site investigation of two subway stations on Xi’an Airport Intercity Railway,that is,North Railway Station（North Square）and Airport West Station,the volumes of piston air is obtained,which is further analyzed with all kinds of control schemes,thus exploring the influence of piston wind on the Ventilation and Air Conditioning system.The test results show that an appropriate volume of fresh air can satisfy people’s demand for fresh air and thermal control,and excessive air infiltration will increase the air conditioning load in the cooling season.Thus,a new operation scheme of subway stations’Ventilation and Air Conditioning system is developed accordingly.The analysis and verification have suggested that the new operation scheme for Ventilation and Air Conditioning system that is able to reduce the energy consumption by200,000 to 400,000 kwh per year,can be put into operation.In view of its effectiveness in reducing subway stations’energy consumption,it can provide a reference and basis for the existing and newly-built metro lines to enhance their energy-saving work.