Development of CNG Injection Engine to Meet Future Euro-V Emission Norms for LCV Applications

Compressed Natural Gas (CNG) is now looked upon as a leading renewable fuel for vehicles in INDIA due to mounting foreign exchange expenditure to import crude petroleum. Impending stringent emissions regulations for diesel engines, specifically exhaust particulate emissions have caused engine manufactures to once again examine the potential of alternative fuels. Much interest has centred on CNG due to its potential for low particulate and hydrocarbon based emissions and adulteration hostile nature. Significant amount of research and development work is being undertaken in INDIA to investigate various aspects of CNG utilization in different types of engines. This paper discusses the methodology for conversion of a diesel engine to dedicated CNG engine and to make the engine to meet EURO-V norms. The primary modifications are made on the piston, cylinder head, intake manifold, throttle body adaptation and exhaust system. Two different configurations like throttle body injection and multi point injection were evaluated. In the initial trials 1.1l intake manifold was used to develop the power greater than 55 kW. When the manifold volume was increased to 4.6l, there was increase in the power and resulted flat torque. As engine is having two intake ports, location of injectors plays important role for getting targeted performance. Selection of ECU, development of logics and right calibration methodology resulted in meeting EURO-V norms. The injection timing, volumetric efficiency estimation, deciding short term and long term fuel trims with respect to engine operations are the key factors for engine calibration. Further the metallic catalytic converter with two brick substrates of 3.8l volume was used. Consistency tests were carried out for assessing the repeatability of results and it is observed that the results are well within EURO-V emission norms with enhanced margins.