Development of a Six Cylinder HCNG Engine Using an Optimized Lean Burn Concept 2009-26-0031

Considering the bleak scenario of rising fossil fuel prices coupled with limited availability and environmental degradation caused by conventional fuels, it is not surprising that the world has turned its attention to use of alternative fuels. The ever increasing demand for ecologically friendly vehicles can only be met by use of ultra clean fuels like CNG and Hydrogen. Traditionally CNG vehicles have been developed in India in variety of segments and have contributed to cleaning the ambient conditions of cities like Delhi. However the persistent NOx levels are becoming a hotly debated issue. One of the solutions to this crisis is the addition of Hydrogen to CNG. The Hydrogen + CNG fuel referred to as HCNG has the potential to lower emissions including NOx as compared to CNG and is considered to be the first step towards promotion of a Hydrogen economy.

This paper presents the optimization strategy for 6-cylinder HCNG naturally aspirated engine using the lean burn concept of combustion. The six cylinder engine was chosen due to its importance for urban bus transportation. In this study the lean burn combustion concept has been evaluated for varying HCNG blends. CFD simulation of the combustion process has also been performed. Identification of optimum blend is one of the objectives of this study. Based on the literature it is obvious that the HCNG engine developed has potential to meet Euro-IV and beyond norms with Injection technology. It is also expected that HCNG fuel blends reduce NOx emissions by approximately 50%, non-methane hydrocarbons by 58%, and total hydrocarbons by 23% and CO₂ by 7% as compared to CNG [1]. No PM emissions are observed in CNG or HCNG engines.