Increasing emphasis on natural gas as a clean, economical and abundant fuel advocates its increasing use in transportation applications. In developing countries like Pakistan and India where, more than 80% of the goods are transported by trucks and where natural gas is available in abundance, development of natural gas conversion systems for heavy-duty truck engines offers a viable option to replace the use of expensive imported fuels.
A complete dual-fuel (natural gas/diesel) conversion system developed using mostly commercially available components, for the Hino EC-100 diesel engine is described. Both diesel and natural gas operating modes are possible, without undermining normal engine performance as a diesel. The conversion system has performance similar to the ‘straight diesel’ operation, with comparable efficiency at full load. Furthermore, particulate and oxide of nitrogen (NOx) emissions are considerably lower than on diesel, however, carbon monoxide and hydrocarbon exhaust emissions are higher, particularly at light load.