CNG has long since been established as a front runner amongst other available alternative fuels. In India, its infrastructure and penetration far exceeds others. While other, more efficient alternatives are been researched, CNG has established itself in the market as the alternative fuel of choice for majority of Indians. CNG technology has evolved itself from the basic venturi system to the more efficient sequential injection system nowadays. While the efficiency of an engine using sequential injection CNG has increased, the inherent problem with respect to lower volumetric efficiency and hence less power still persists.
Direct injection CNG technology is seen as the solution to this age old problem. In the older days, the lack of technological expertise in SI direct fuel injection provided a stumbling block for development of direct gas injection. But with the surge in technological advancement lately, especially in the gasoline direct injection area has opened new avenues for development of gas direct injection technology. DI CNG technology has the benefits of increased power, improved BSFC and lower emissions. Further the challenges in this technology are lower injector life and expensive modifications in the MPFI technology.
In this paper we look at the various injection strategies, experiments and simulation analysis carried out worldwide on DI CNG technology and the potential this area has in unleashing the true benefits of CNG fuel. Further this research will help us in developing our own DI CNG engine in the future.