Numerical Predictions of In-Cylinder Phenomenon in Methanol Fueled Locomotive Engine Using High Pressure Direct Injection Technique

Petroleum products are used to power internal combustion engines (ICEs). Emissions and depletion of petroleum reserves are important questions that need to be answered to ensure existence of ICEs. Indian Railways (IR) operates diesel locomotives, which emit large volume of pollutants into the environment. IR is looking for an alternative to diesel for powering the Locomotives. Methanol has emerged as a replacement for petroleum fuels because it can be produced from renewable resources as well as from non-renewable resources in large quantities on a commercially viable scale. It has similar/superior physico-chemical properties, which reduce tailpipe emissions significantly. It is therefore necessary to understand the in-cylinder phenomenon in methanol fueled engines before its implementation on a large-scale. In this study, efforts have been made to understand the in-cylinder phenomenon in large-bore locomotive engines using CFD tools. 3-D model was prepared and validated using the experimental data of the baseline diesel. Afterward, this validated model was modified for 90% diesel replacement (on energy basis) by methanol in the engine by employing high pressure direct injection (HPDI) technique via a co-axial injector. Pilot diesel injection was used to ignite the methanol-air mixture. Optimized dimensions of co-axial injector obtained from 1-D simulation were used as primary inputs to the 3-D model. This study provided insights into complex combustion phenomenon of methanol-fueled locomotive engine using HPDI technique. 3-D model was used to understand spatial and temporal variations of different combustion parameters such as in-cylinder pressure variations, temperature variations, fuel-air mixing processes, etc. From the simulation study, it was concluded that locomotive engine fueled with methanol and pilot diesel shows more homogeneous fuel-air mixture compared to only diesel fueling. Also, the maximum in-cylinder temperature for methanol fueled locomotive was found significantly lesser vis-à-vis diesel-fueled which led to lesser NOx formation.