Diesel fuel used in locomotives generally does not pose a fire hazard. However, diesel vapor generated within tank vapor space attains flammability condition as the fuel temperature gets closer to the fuel-flash point, which may cause a fire hazard in the event of a tank breach due to collision or derailment of the locomotive. As a part of an ongoing Federal Railroad Administration (FRA) sponsored research effort, a proof-of-concept laboratory scale demonstration has shown that it is possible to circulate the mixture of diesel vapor and air through a small vapor condenser unit to reclaim the fuel vapor. The recovered fuel is shown to possess almost similar specific heat value and hydrocarbon constituents as that of neat diesel fuel and hence reusable. Furthermore, the vapor reclamation process enables mitigation of fire hazard and reduction of diesel vapor escape to the environment. In order to assess the real potential of diesel vapor reclamation on a running locomotive, real-time fuel temperature data was collected during a medium-haul run of a BNSF Railway freight locomotive.
This paper presents the real-time fuel temperature data collected on a BNSF Railway instrumented locomotive tank as well as results of computational fluid dynamics (CFD) analyses performed for the full-scale locomotive tank. In continuation of the research and development effort, the design of a scaled up diesel vapor reclamation system is presented. The scope of its integration with a railroad freight locomotive is summarized and subsequent steps for its performance evaluation on a running locomotive are discussed.