CFD analysis of diesel emissions in a railroad tunnel

摘要

Computational fluid dynamics (CFD) modeling can be used to predict three-dimensional distribution of diesel emissions gases in underground mines and tunnels. This paper presents the results of transient CFD simulations performed for a passenger railroad tunnel utilizing diesel locomotives. Both natural and mechanical ventilation systems were evaluated for a stopped passenger train operating in "hotel mode" (diesel engine running to supply lights and air conditioning/heating to passenger cars). The mass flow rate and temperature of diesel engine exhaust products were modeled at the locomotive exhaust port location. Concentrations of nitrogen dioxide (NO_2), the critical diesel exhaust product for railroad tunnels, were evaluated at the air intake port locations of the passenger cars. In addition, the simulations enabled NO_2 levels at the passenger car intake ports and the sampling locations for the NO_2 gas detection system used to control the ventilation system for the tunnel to be compared.