Assessing the Impact of Lubricant and Fuel Composition on LSPI and Emissions in a Turbocharged Gasoline Direct Injection Engine

Abstract

<div class="section abstract"><div class="htmlview paragraph">Downsized turbocharged gasoline direct injection (TGDI) engines with high specific power and torque can enable reduced fuel consumption in passenger vehicles while maintaining or even improving on the performance of larger naturally aspirated engines. However, high specific torque levels, especially at low speeds, can lead to abnormal combustion phenomena such as knock or Low-Speed Pre-Ignition (LSPI). LSPI, in particular, can limit further downsizing due to resulting and potentially damaging mega-knock events. Herein, we characterize the impacts of lubricant and fuel composition on LSPI frequency in a TGDI engine while specifically exploring the correlation between fuel composition, particulate emissions, and LSPI events. Our research shows that: (1) oil composition has a strong impact on LSPI frequency and that LSPI frequency can be reduced through a carefully focused approach to lubricant formulation. In addition, (2) we observed significant improvement potential in Brake Mean Effective Pressure (BMEP) achievable with zero LSPI events using both experimental and market-representative lubricant formulations. Finally, (3) fuels blended with high polyaromatic content were shown to increase LSPI frequency significantly; these fuels also caused a significant increase in particulate mass (PM) and particulate number (PN) emissions. In this paper, we discuss the above results along with the development and use of a high-fidelity test method to measure LSPI under steady-state test conditions.</div></div>

Fuel-Lubricant Interactions: Critical Review of Recent Work

“…The authors also found that decreased LSPI severity corresponded with increased octane numbers and higher ethanol content of the market fuels. A number of published studies have investigated fuel lubricant interactions on LSPI [46][47][48]. Hu et al [46] found that the properties of oil particles entering the engine cylinder were significantly affected by fuel dilution.…”

“…As expected, the combination of a high LSPI activity fuel and a high LSPI activity lubricant resulted in large numbers of LSPI events. Kar et al [48] found that the oil composition had a strong impact on LSPI frequency and that LSPI frequency could be reduced by changing the lubricant formulation. In addition, it was found that fuels blended with high polyaromatic content increased LSPI frequency significantly and also caused a significant increase in particulate mass and particulate number emissions.…”

Fuel-Lubricant Interactions: Critical Review of Recent Work

“…The authors also found that decreased LSPI severity corresponded with increased octane numbers and higher ethanol content of the market fuels. A number of published studies have investigated fuel lubricant interactions on LSPI [42][43][44]. Hu et al [42] found that the properties of oil particles entering the engine cylinder were significantly affected by fuel dilution.…”

“…As expected, the combination of a high LSPI activity fuel and a high LSPI activity lubricant resulted in large numbers of LSPI events. Kar et al [44] found that the oil composition had a strong impact on LSPI frequency and that LSPI frequency could be reduced by changing the lubricant formulation. In addition, it was found that fuels blended with high polyaromatic content increased LSPI frequency significantly and also caused a significant increase in particulate mass and particulate number emissions.…”

The comparative performance study of the EF7 downsized engines; fuel economy besides CO2 reduction

“…Using modified inlet components design [19], developed TC such as Variable Geometric Turbines (VGT) [20] and twin-turbines [21], improved injection strategy [22], water injection [23], employing additives [24], combined [25] and alternative [26] fuels, Exhaust Gas Recirculation (EGR) [27], and electrified components [28] are considered as the some of these techniques. It is asserted that both fuel economy and 𝐶𝑂 2 production rate are noticeably improved during these efforts, but some challenging issues such as knock [29] and super-knock [30], Low-Speed Pre-Ignition (LSPI) [31], and weak performance especially at low-speed regions [32] are the main obstacles which researchers try to cope with them. Indeed, to achieve the ultra-emission reduction goal, the efforts lead to the usage of Compressed Natural Gas (CNG) as the fuel of downsized engines [33][34][35].…”