Impact of emerging engine and after-treatment technologies for improved fuel efficiency and emission reducion for the future rail diesel engines

The future stringent emission limits and fuel-savingrequirements for non-road engines, in particular for the railsector, require further research investments both on engineand after-treatment technologies. Therefore, the aim of thisstudy is to identify, mainly on a literature data base, the mostpromising emerging engine technologies (waste heat recovery,turbocharging, etc.) and exhaust after-treatment systems(de-NOx catalyst systems, particulate filters, etc.) for improvedfuel efficiency and emissions reduction of rail diesel engines.The considered technologies are currently from productionseries or under development mostly in the on-road researchdomain. The approach taken has been to gather available informationand data from research and industry sources for themost promising emerging technologies of on-road heavy-duty(HD) engines. The collected data have been properly analyzedand elaborated in order to identify the most transferable datafrom road to the rail sector. The study is one of the results of aproject carried out within the 7th European Framework programin which several academic and industrial partners haveparticipated. Engine side and exhaust after-treatment systemside technologies are discussed separately. The former takesinto account quantitative data from the literature survey, mainlyin terms of fuel efficiency benefits, and summarizes theevaluation in a return on investment calculation on the baseof a reference rail engine cost. In the latter, essentially qualitativeinformation has been collected. The analysis has beencarried out by means of spider diagrams that are used to showthe potential of the grouped after-treatment technologies interms of pollutant emission reduction, size/weight reduction,technology maturity, and cost reduction. The results indicatethat the emerging engine technologies are mostly about engineefficiency improvements, of which waste heat recovery showsthe greatest potential in terms of fuel efficiency improvement.On the after-treatment system side, the integration of multipleafter-treatment functionalities into a single device is particularlyattractive for rail applications because it could significantlydecrease space and weight requirements, as could theuse of alternative to urea media for ammonia storage in thecase of selective catalytic reduction (SCR) systemfunctionalities.