An experimental and numerical study on diesel injection split of a natural gas/diesel dual-fuel engine at a low engine load

Experimental Study on the Effects of Air Supply Control on Combustion and Emissions Performance at Medium and Low Load for a Dual-Fuel Diesel Engine

“…Under dual-fuel working conditions, ITE is promoted with the increase of substitution rate. Previous work pointed out that delayed ignition helps to form more fuel-air mixture before the start of combustion, which favors the formation of the ignition kernel [7]. Herein, as the HRR profiles show in Figures 4 and 5, the ignition delay is delayed and combustion phasing is retarded because of the smaller pilot diesel injection with the increase of substitution rate.…”

“…The effects of pilot injection timing, pilot injection pressure and NG injection timing on the combustion performance and emissions for a four-cylinder turbocharged diesel engine with common rail injection at low load operations have been analyzed, and the results indicated that retarded natural gas injection timing can represent an effective method to improve the combustion performance and exhaust emissions at low load [6]. A split injection strategy for the diesel pilot to increase the in-cylinder peak pressure and thermal efficiency at low loads by an experimental and numerical study were described [7]. At the same time, a split injection strategy provided an effective approach to accomplish the trade-off between NOx-CH 4 and NOx-CO emissions [7].…”

“…A split injection strategy for the diesel pilot to increase the in-cylinder peak pressure and thermal efficiency at low loads by an experimental and numerical study were described [7]. At the same time, a split injection strategy provided an effective approach to accomplish the trade-off between NOx-CH 4 and NOx-CO emissions [7]. The influences of methane substitution ratio, the usage of exhaust gas recirculation (EGR) and pilot injection strategy on engine performance and emissions at low loads were studied in [8], and the study reported that the increase of methane substitution ratio obviously contributed to the high level of HC and CO emissions, the lower combustion rate and the lower combustion efficiency at low loads.…”

Ignition characteristics of dual-fuel methane-n-hexane-oxygen-diluent mixtures in a rapid compression machine and a shock tube

“…Properly optimized, the adoption of the pilot injection strategy would reduce the delay to the main ignition event, smoothen the premixed combustion phase, as well as reduce noise and pollutant emissions at partial loads [14,15,16,17]. However, because of the complexity of spray-induced ignition, substantial efforts are needed to optimize the combustion chamber geometry, the spray characteristics and the ignition strategies [18,19,20,21,22,14,23,24]. In order to reducing the dependence on engine tests and to improving work efficiency, such an optimization process could be performed using Computational Fluid Dynamics (CFD) simulations, coupling the fluid mechanics and the appropriate chemical kinetic mechanism.…”

Injection systems in diesel engines and their theoretical-experimental study: a review

“…An example of the first-mentioned approach is the work of Luo [21], in which they make a modeling of each 1 of the orifices of a multi-orifice injector or Long Liu's work [22], which develops a model for the simple and analytical diesel pulverization, which includes the evolution of the spray after the end of the injection. On the other hand there are works that follow the second approach as the work of Amin Yousefi [23] that models different types of injection for heavy services at low loads or that of Madjid Birouk [24] that analyzes the effect of the injection delay on the Emissions, both choose to follow the system of Navier-stokes equations, others like Pang Kar [25] choose to follow a Eurelian stochastic method to know how the ignition flame develops. In the case of the third approach we have works such as Rao [26], which measures the effect of post-injections on emissions in small diesel engines with optical exams to experimental designs or the work of Seoksu Moon [27] who opts for the use of x-rays to discover how the injector needle affects the flow through each orifice of the injector in single hole, 3-hole, and 6-hole injectors.…”