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Experimental data and modeling work have shown that gasoline-like fuels can potentially be used to simultaneously achieve high efficiency and low pollutant emissions in compression ignition engines. Demonstrating that existing hardware systems are tolerant to these fuels is a key step in harnessing this potential. In this study, a 400-hour North Atlantic Treaty Organization (NATO) test cycle was used to assess the overall robustness of a Cummins XPI common-rail injection system operating with gasoline-like fuel. The cycle was designed to accelerate wear and identify any significant failure modes that could appear under normal operating conditions. Although prior work has investigated injection system durability with a wide variety of alternative fuels, this study uniquely focuses on a high-volatility, low-viscosity, gasoline-like fuel that has been dosed with lubricity additive.

Lubricity is an empirically-determined tribological property, which is a function of the fluid properties and system, and which is known to influence fuel system wear durability. In this work, the lubricity of various fuels was tested using a modified version of ASTM D6079, which uses a high frequency reciprocating rig (HFRR). The fuels were tested as received and with various amounts of commercial diesel lubricity additives. Lubricity of all light-end fuels test as received (without lubricity additives) was found to be substantially worse than additized diesel certification fuel, and lowest for unadditized straight-run gasoline. All diesel lubricity additives tested were able to substantially improve the lubricity of the light-end fuel formulations. The best additives reduced the wear scar diameter in the HFRR test to around 200 μm at a concentration of 200 mg/kg, putting them well within the maximum allowable limit for market No. 2 diesel fuel.

It is well known that in-nozzle flow behavior can significantly influence the near-nozzle spray formation and mixing that in turn affect engine performance and emissions. This in-nozzle flow behavior can, in turn, be significantly influenced by fuel properties. The goal of this study is to characterize the behavior of two different fuels, namely, a straight-run naphtha that has an anti-knock index of 58 (denoted as “Full-Range Naphtha”) and n-dodecane, in a simulated multi-hole common-rail diesel fuel injector. Simulations were carried out using a fully compressible multi-phase flow representation based on the mixture model assumption with the Volume of Fluid method. Our previous studies have shown that the characteristics of internal and near-nozzle flow are strongly related to needle motion in both the along- and off-axis directions.

This research investigates the combustion characteristics and engine performance of a conventional non-ethanol gasoline with a research octane number of 91(RON 91) and a higher reactivity RON80 gasoline under mixing-controlled combustion. The work was conducted in a model year 2013 Cummins ISX15 heavy-duty diesel engine. A split fuel injection strategy was developed to address the long ignition delay and high maximum pressure rise rate for the two gasoline fuels. Using the split fuel injection strategy, steady-state NOx sweeps were conducted at 1375 rpm with a load sweep from 5 to 15 bar BMEP. At 5 and 10 bar BMEP, both gasolines consistently exhibited lower soot levels than ULSD with the reduction more pronounced at 5 bar BMEP. 3-D CFD combustion simulation suggested that the higher volatility and lower viscosity of gasoline fuels can help improve the in-cylinder air utilization and therefore reduce the presence of fuel-rich regions in the combustion chamber.

Investigating combustion characteristics of oxygenated gasoline and gasoline blended ethanol is a subject of recent interest. The non-linearity in the interaction of fuel components in the oxygenated gasoline can be studied by developing chemical kinetics of relevant surrogate of fewer components. This work proposes a new reduced four-component (isooctane, heptane, toluene, and ethanol) oxygenated gasoline surrogate mechanism consisting of 67 species and 325 reactions, applicable for dynamic CFD applications in engine combustion and sprays. The model introduces the addition of eight C1-C3 species into the previous model (Li et al; 2019) followed by extensive tuning of reaction rate constants of C7 - C8 chemistry. The current mechanism delivers excellent prediction capabilities in comprehensive combustion applications with an improved performance in lean conditions.

Onboard reforming has been proposed as a strategy for improving spark-ignited (SI) engine efficiency through knock reduction, dilution limit extension, improved thermodynamic gas properties, and thermochemical exhaust enthalpy recuperation. One approach to onboard fuel reforming is to combust fuel in the engine cylinder under rich conditions, producing a hydrogen-rich reformate gas--which can subsequently be recirculated into the engine. Hydrogen is the preferred product in this process due to its high flame speed and knock resistance, compared with other reformate constituents. In this work, the effects of engine operation, fuel composition and water injection were evaluated for their effect on reformate gas composition produced under rich combustion conditions. Engine parameters, including intake pressure, intake temperature, combustion phasing, and valve timing all had no significant impact on hydrogen yield at a given equivalence ratio.