Prospects of Gasoline Compression Ignition (GCI) Engine Technology in Transport Sector

Abstract

Compression ignition (CI) engines are mainly fuelled by diesel-like high cetane fuels, and they have higher overall efficiency due to higher compression ratio compared to their spark ignition (SI) engine counterparts. However, modern diesel engines are more expensive, complicated, and emit high nitrogen oxides (NOx) and particulate matter (PM). Simultaneous control of soot and NOx emissions in diesel engines is quite challenging and expensive. Thermal efficiency of SI engines, on the other hand is limited by the tendency of abnormal combustion at higher compression ratios therefore use of high octane fuel is essential for developing more efficient higher compression ratio SI engines in near future. In the foreseeable future, refineries will process heavier crude oil to produce relatively inferior petroleum products to power the IC engines. Also, fuel demand will shift more towards diesel and jet fuels, which would lead to availability of surplus amounts of low octane gasoline with oil marketing companies, with little apparent use for operating the engines. This low octane gasoline will be cheaper and would be available in excess quantities in foreseeable future as the demand for gasoline will further drop due to increase in the fuel economy of modern generation gasoline fuelled vehicles. For addressing these issues, Gasoline compression ignition (GCI) engine technology is being developed, which is a futuristic engine technology that takes advantage of higher volatility, and higher auto-ignition temperature of gasoline and higher compression ratio (CR) of a diesel engine simultaneously to take care of soot and NOx emissions without compromising diesel engine like efficiency. GCI engines can efficiently operate on low octane gasoline (RON of ~70) with better controls at part load conditions. However cold starting, high CO and HC emissions, combustion stability at part load, and high combustion noise at medium-to-full load operations are some of the challenges associated with GCI engine technology. Introductory sections of this chapter highlights future energy and transport scenario, trends of future fuel demand, availability of low octane fuels and development in advanced engine combustion technologies such as HCCI, PCCI, RCCI, and GDI. GCI engine development, its combustion characteristics and controls are discussed in detail. Particular emphasis is given to the effect of various control strategies on GCI combustion, performance and emissions, fuel quality requirement and adaption of GCI technology in modern CI engines. In addition, this chapter reviews initial experimental studies to assess the potential benefits of GCI technology.