Numerical Analysis of the Effects of Direct Dual Fuel Injection on the Compression Ignition Engine

Abstract

In this work, the influence of direct dual fuel injection on a compression ignition engine fueled with gasoline and diesel has been investigated. To do this, closed cycle combustion simulations have been performed. Gasoline has been supplied through port injection and early direct and late direct injection to achieve fuel stratification and emission reduction. Simulations have been done for various start of injection (SOI) timings of diesel fuel. A detailed discussion on a low temperature heat release (LTHR) mechanism has been done. Results revealed that the maximum gross indicated thermal efficiency (GITE) of 39% is obtained for port injection of gasoline mode. Direct dual fuel combustion (type 2) (DDC2) mode shows approximately 2% and 38% less GITE and oxides of nitrogen (NOx), respectively, and 40% more soot as compared to the port injection gasoline mode. DDC2 mode shows lower oxides of carbon and hydrocarbon emissions as compared to other dual fuel modes. More than 99% of combustion efficiency and less maximum pressure rise rate have been noticed in the DDC2 case. Strong LTHR and high temperature premixed combustion region have been found in advanced SOI timing cases (in DDC2). In-cylinder contours for the DDC2 case show that diesel and gasoline fuels combusted successively cause less in-cylinder temperature than that for the conventional dual fuel combustion case.

Preliminary experimental data analysis for Digital Twin development of a large bore Dual-Fuel engine

“…The analyzed input variables are the Pilot Fuel Injection Timing, Scavenging Air Pressure and Pilot Fuel Injection Duration; the target variables are: NOx and Hydrocarbons (HC) emissions, Engine Efficiency, In-Cylinder Pressure and Combustion Duration. Pilot injection timing is a term used in Diesel and DF engines to describe the timing at which a small amount of fuel is injected into the combustion chamber before the main injection event [26].…”

Detailed Analysis of the Effects of Biodiesel Fraction Increase on the Combustion Stability and Characteristics of a Reactivity-Controlled Compression Ignition Diesel-Biodiesel/Natural Gas Engine

“…The RCCI combustion mode uses two or more fuels with different reactivity. The low-reactivity fuel is often injected into the engine intake port, and high-reactivity fuel is directly injected into the combustion chamber for combustion phasing control [10]. With the help of the reactivity gradient difference between the two fuels and setting an optimized start for the injection timing, a high-efficiency combustion mode with low NOx and soot emissions is achieved [11][12][13] .…”

Combination of Pilot Injection and a NH3-SCR System To Reduce NOx Emissions of a Nonroad Compression Ignition Engine

“…Pilot injection and selective catalytic reduction (SCR) are two effective techniques for the mitigation of NOx emissions from diesel engines. Pilot injection is a shorter injection before the main fuel injection, which can provide an environment of high temperature and pressure for the main injection resulting in a smoother pressure rise and shortened ignition delay for the main injection. , Owing to the shorter ignition delay, less combustible mixture is generated before the ignition event, leading to decreases in the premixed burn fraction and combustion temperature, finally reducing the NOx formation. , The efficacy of pilot injection in reducing the content of NOx emissions depends on the injected fuel quantity and the interval between pilot- and main-injection events. Huang et al experimentally studied the effects of the pilot-injection fuel amount and the pilot-main interval on NOx emissions of a compression ignition (CI) engine.…”

“…Pilot injection is a shorter injection before the main fuel injection, which can provide an environment of high temperature and pressure for the main injection resulting in a smoother pressure rise and shortened ignition delay for the main injection. 5,6 Owing to the shorter ignition delay, less combustible mixture is generated before the ignition event, leading to decreases in the premixed burn fraction and combustion temperature, finally reducing the NOx formation. 7,8 The efficacy of pilot injection in reducing the content of NOx emissions depends on the injected fuel quantity and the interval between pilot-and main-injection events.…”