Subway Tunnel Temperature Characteristics And Its Impact On The Site Environment

In recent years, the city scale expands unceasingly, the urban rail transit has beenbeing developing strongly. subway construction locates generally about ten meters ormore underground, so it must rely on environmental control system to ensure thepassengers’ comfort, normal operation of equipment and so on. But the operationconsumption of the control system accounts for about50%of the total operationconsumption of the subway. This paper is to study the subway tunnel air temperaturecharacteristics which are in relation to energy efficiency of air conditioning system andthe influence of piston wind on the station platform environment.Firstly, the author analyzed the heat sources during the train operation period,including heat production caused by train running, rock heat transfer, heat carried by airwhen it flowed into and out of the control volume, the tunnel lighting heat. Thencalculated air temperature prediction formula in the tunnel according to the heat balance.And took Shenzhen subway line three, a typical tunnel, as an example to calculate theair temperature in the tunnel.Secondly, the author measured the air temperature in the subway tunnel and madecomparison among the calculation results, test results and numerical simulation tests ofthe subway environment simulation program SES. The three results are similar, theresults of numerical simulation value and calculation value is lower than the test, adifference of about0.27℃. The accuracy of the tunnel temperature calculation formulahas been verified, and can be spread in engineering design. It also proved the subwayenvironment simulation program SES is credible. In addition, the author has obtainedthe variation of the air temperature and wall temperature inside the tunnel in the nightby field tests, which can provide basic information for the study of the thermalenvironment inside the tunnel.Thirdly, the author simulated the subway air temperature at late evening, the mostunfavorable conditions in the tunnel with SES software, which can provide the basis forthe design of tunnel ventilation; and explored the influence of outside air temperatureand the number of train on the air temperature in the tunnel. The results showed that thetunnel air temperature increased with ambient temperature and the number of train,variation of air temperature in the tunnel is influenced by the ambient temperaturesmaller than the number of train, and the smaller the number of the train is, the more temperature changes in the tunnel.Finally, the author took a typical station of Shenzhen metro line three as anexample to establish ventilation network to calculate values of air leakage through PSD,and tested the air flow rate on both sides of PSD. Then the test results were comparedwith the calculated results, and to be found little difference between the two and theinfluence of tunnel piston flow on the platform environment was small, air flowing fromthe site to tunnel accounted for92.9%of the total amount of air exchange through bothsides of PSD.