The Energy-Saving of Urban Tunnel Ventilation Based on the Investigation of the Annual Discount Rate of CO Baseline Emission in City of Shenzhen

Abstract

Abstract Tunnel ventilation problems and energy-saving issues are key factors that have restricted the development of highway tunnels, especially in the context of urban tunnels. In this article, a detailed field measurement was carried out from March 29th to September 16th, 2014, in four typical urban tunnels: Henglongshan Tunnel, Cejiexian Tunnel, Jiuweiling Tunnel, and Dameisha Tunnel in Shenzhen, China. Against this backdrop, the main objective of this article was to optimize the urban tunnel ventilation design system via back calculating a reasonable discount rate of carbon monoxide (CO) baseline emission in the basis of measurement results of traffic flow, air velocity, and CO concentrations within the unban tunnels in Shenzhen. Measurement results reveal that traffic flow in urban tunnels increased to the design level, even beyond the design values. Air velocities in four tunnels were found to be lower than 5 m·s−1 and fluctuated widely during the day. Furthermore, the CO concentration peaks of the Henglongshan Tunnel, Cejiexian Tunnel, Jiuweiling Tunnel, and Dameisha Tunnel stood at 17 cm3·m−3, 7 cm3·m−3, 39 cm3·m−3, and 6 cm3·m−3, respectively. Most importantly, the necessary air volume was calculated in accordance with measured traffic parameters and other parameters in the specification were found to be much higher than actual air supply. Based on large amounts of measured data, the annual discount rates of CO baseline emission which were between 4.9∼12.6 %, have been acquired using the method of inversion calculation for the first time. Therefore, it is recommended to take 8 % as the annual discount rate of CO baseline emission in Shenzhen’s urban tunnel ventilation design; these experimental data also provide a reference for other relevant regions.