A TECHNICAL REVIEW OF PERFORMANCE OF CNG DIRECT INJECTION IN SPARK IGNITION ENGINE
Keywords:
CompressedNaturalGas (CNG); CNG DirectInjection (CNG-DI); Spark Ignition (SI); Port Injection (PI); CNG Bi fuel(CNG-BI)Abstract
Compressed Natural gas(CNG) is one of the most valuable alternative fuels due to its cleanest burning
characteristic and high octane number. Now-a-days, most of the vehicles use Port Injection(PI) system for injecting
CNG. This paper presents a new concept of injecting CNG directly into the cylinder which is known as CNG-DI. In SI
engine, CNG-DI technology significantly increases the volumetric efficiency and thereby increases the burning
efficiency.This CNG-DI technology also permits the use of extremely lean air-fuel mixture in the engine and reduces the
fuel use of goods and services.In adopting the CNG-DI technology, the engine requires certain modification. The
cylinder head must be modified so that, it can accommodate the gas injector which is specially developed for injecting
CNG in the cylinder by making holes near the spark plug in the body. The spark plug and gas injector further
connectwith timer device. The suitable gas metering system is too integrated with the CNG storage tank.This paper gives
a technical introduction of CNG-DI system over the conventional PI and sequential injection
