Intake and Exhaust Valve Timing Control on a Heavy-Duty, Direct-Injection Natural Gas Engine

Fuel Effects on PM Emissions from Different Vehicle/Engine Configurations: A Literature Review

“…GDI vehicle data were obtained from 18 studies, including references [13], [14], [16], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35]. The largest sources of data for GDI vehicles included Coordinating Research Council (CRC) programs [20], [21], [22], the European 'PARTICULATES' program [23], the University of California at Riverside (UCR) College of Engineering-Center for Environmental Research and Technology (CE-CERT) mixed alcohol program [19], [24], and the European Petroleum Refiners Association program [25], each of which accounted for over 100 test records.…”

“…For the GDI vehicles, emissions results were obtained from 38 different model vehicles and 78 different types of fuels. PFI vehicle data were obtained from 15 studies, including references [13], [14], [16], [17], [19], [23], [24], [25], [26], [27], [28], [29], [36], [37], [38], [39], [40]. The largest sources of data for PFI vehicles included the Energy Policy Act (EPAct)/E-89 program [17], [36] and Sobotowski et al [16], which included 955 and 270 test records, respectively, or 1235 of the total of 1841 test records.…”

Numerical studies of the ignition characteristics of a high-pressure gas jet in compression ignition engines with glow plug ignition assist: Part 2-Effects of multi-opening glow plug shields

“…Spark ignition is reliable and widely used on homogeneous charge natural gas engines, 4,5 but has seen limited application to HPDI natural gas engines. Pilot injection of diesel fuel is the most widely used form of ignition assist for HPDI natural gas engines 6–8 and is also preferred ignition source for dual fuel (diesel pilot injection–natural gas fumigation) engines. 9–16 The effect of various operating parameters, such as the valve timing 7 and the injection pressure, 8 on the performance and emissions of a HPDI natural gas engine has been widely investigated.…”

Improving cold start, combustion and emission characteristics of a lean burn spark ignition natural gas engine with multi-point hydrogen injection

“…Due to the energy security, the search for alternative fuels for use in the internal combustion engine, such as biodiesel, natural gas, ethanol, dimethyl ether, hydrogen gas (H 2 ) etc., is a hot topic for researchers. Natural gas has potential for transportation applications [1], because of its reduced environmental burden relative to conventional fuels and its applicability to conventional diesel (dual fuel) [2] and gasoline engines (port or direct injection) [3,4]. Moreover, the use of natural gas could result in lower nitrogen oxides (NOx), carbon monoxide (CO), and non-methane hydrocarbon (HC) emission levels, by using a simple after-treatment device, and it is almost free of particulate emissions [5].…”

“…Because of the high octane number (between 120 and 130) and high anti-knocking potential of natural gas, CNG engine has high tolerance for high compression ratios [6]. However, due to the lower flame velocity and the narrower flammability limits of natural gas [7], a natural gas spark ignition engine has the weaknesses, such as large cycle-to-cycle variations, poor lean-burn capability, and poor exhaust gas recirculation (EGR) tolerance, which could decrease the engine power output and the thermal efficiency and increase fuel 4 consumption. Lean burn natural gas engines have become more attractive as they are highly efficient due to the lower heat and pumping losses and the excess air.…”