Effects of direct injection timing of ethanol fuel on engine knock and lean burn in a port injection gasoline engine

Abstract

Improving engine efficiency and reducing its emissions are the major tasks of recent development in internal combustion technology [1]. This is driven by the society concerns about the global warming and the depletion in supply of fossil fuels. One of the feasible short-to-midterm solutions for addressing the concerns is to use renewable fuels such as ethanol. Many countries and areas have enacted legislations [2] or incentive policies to promote the use of ethanol and other bio/renewable fuels [3,4]. The use of ethanol and other bio/renewable fuels has brought new challenges to automotive sector to develop new technologies. Ethanol direct injection plus gasoline port injection (EDI + GPI) is one of the new technologies in recent development.Previous studies on SI engines found that using ethanol fuel could help to reduce unburned emissions such as carbon monoxide (CO) and hydrocarbon (HC) [5][6][7], enhance engine anti-knock ability [8,9], and improve lean burn performance [10,11]. In the current applications, ethanol is externally blended with gasoline at a specific ratio. The applications of this method decreased pollutant emissions and increased engine efficiency in certain engine conditions [12,13]. However, the vehicles may face problems of reduced vehicle coverage, difficult cold start [14], corrosion and reduced lubrication [15]. Moreover, due to the fixed ethanol/gasoline ratio, the ethanol's potential in reducing engine emissions and improving thermal efficiency cannot be fully exploited. Research has already shown that the optimal ethanol/gasoline ratio for maximizing engine efficiency and minimizing emissions was varied with the engine operation condition [6,7]. EDI + GPI dual-fuel injection, on the other hand, provides an opportunity to solve the problems and meet the requirements. It offers greater flexibility of using ethanol fuel because the ethanol and gasoline mixing ratio can be instantly altered according to the engine operation Effects of direct injection timing of ethanol fuel on engine knock and lean burn in a port injection gasoline engine AbstractEthanol is a promising alternative fuel for internal combustion engines due to its renewable feature. To make the use of ethanol fuel more effective and efficient, ethanol direct injection plus gasoline port injection (EDI + GPI) has been investigated in recent years. By directly injecting ethanol into the engine, the advantages of ethanol fuel such as high latent heat of vaporization, fast laminar flame speed, wide flammability and better low temperature combustion stability can be well utilized to enhance engine anti-knock ability and improve lean burn performance. For an engine equipped with direct injection (DI) system, start of injection (SOI) timing is an important control parameter which directly affects the engine performance. This paper reports the investigation to the effect of ethanol fuel SOI timing on knock mitigation and lean burn. Experiments were conducted on a 250 cc single cylinder spark ignition (SI) engine equipped with EDI ...

Effect of injection timing on mixture formation and combustion in an ethanol direct injection plus gasoline port injection (EDI+GPI) engine

“…In high-velocity flows, the effect of convective flow on taking the evaporating material from the droplet surface to the bulk gas phase becomes significant. and 250 CAD BTDC in the engine experiments, as reported in [31]. The lower evaporation rate of late EDI injection has significant effect on the following combustion process.…”

“…Experimental results showed that late EDI timing allowed more advanced spark timing without knock issue than early EDI timing did, but also deteriorated the combustion and emission performance of the engine [31]. As shown in Fig.…”

Recent Progress in Automotive Gasoline Direct Injection Engine Technology

“…2 First proposed by Ikoma et al [22], such systems provide more flexibility in terms of control, particle reduction and knock suppression [23][24][25][26] and are currently used in GDI engines [14].…”

The competing chemical and physical effects of transient fuel enrichment on heavy knock in an optical spark ignition engine

“…The complexity is arguably further exacerbated by emerging future fuels, where a fuel such as ethanol with high sensitivity (i.e. relatively high RON but low MON) may help reduce the onset of knock [1,[33][34][35] but could theoretically exacerbate sporadic pre-ignition under certain conditions due to the increased pre-ignition tendency as indicated by the lower MON rating [36].…”