Biodiesel PCI Combustion for Performance and Emission Improvement in a Compression Ignition Engine

Abstract

Low-temperature combustion has the potential to reduce nitrogen oxides (NO x ) and particulate matter (PM) emissions; however, it faces the challenge of high level of hydrocarbon (HC) and carbon monoxide (CO) emissions. Application of oxygenated fuel such as biodiesel to LTC has gained interest to overcome this drawback. This study aims to provide a comprehensive understanding of the influence of biodiesel on premixed compression ignition (PCI) in a single-cylinder compression ignition engine. A series of engine tests were carried out at an engine speed of 1200 rev/min with two injection pressures (800 bar and 1600 bar), two injection timings (25 and 5 crank angle degree (CAD) before top dead center (bTDC)), and four exhaust gas recirculation (EGR) rates (0–30%). Engine performance results showed that fuel consumption with PCI combustion was higher than that with conventional diesel combustion (CDC) due to the advanced combustion phase. The lower heating value of biodiesel resulted in approximately 10% higher fuel consumption than diesel regardless of test conditions. In terms of emissions, PCI combustion indicated higher carbon CO and HC emissions because of liquid fuel flow in squish areas with early injection timing supported by a Lagrangian spray simulation. However, the application of biodiesel in PCI combustion was beneficial to suppress CO and HC emissions while maintaining low levels of NO x and PM emissions compared to CDC condition. Especially, the PN emission under PCI biodiesel condition was 1/10 of CDC. Soot morphology by TEM imaging showed a smaller primary particle diameter with biodiesel, attributed to enhanced soot oxidation.

Advancements in In-Cylinder and After-Treatment Strategies for Mitigating Pollutants from Diesel Engines: A Critical Review

“…Thus, the degree of fuel-air premixing is not as high as in HCCI. Fuel is injected early during the compression stroke to form a homogeneous fuel-air mixture, whose ignition is controlled by the injection timing and the chemical kinetics . However, too advanced fuel injection leads to spray wall impingement and thus unacceptably high HC emissions .…”

“…Fuel is injected early during the compression stroke to form a homogeneous fuel-air mixture, whose ignition is controlled by the injection timing and the chemical kinetics. 121 However, too advanced fuel injection leads to spray wall impingement and thus unacceptably high HC emissions. 122 The PCCI strategy has recently been implemented by prolonging the ignition delay period using excessive charge dilution and reduced compression ratio to prepare the homogeneous fuel-air mixture with the fuel injection event near the top dead center (TDC).…”

Ethers and esters as alternative fuels for internal combustion engine: A review

“…EGR has little effect on particle size and mass distribution, and mainly affects the total number and mass of particles. In addition to EGR, 189 water injection (WI), emulsification technology (ET), injection strategy optimization, combustion chamber optimization and low temperature combustion (LTC) mode 190 can also improve the shortcomings of high NO x emissions of biodiesel. Among them, the LTC mode is more effective than other methods, which can reduce 95% NO x and 98% PM emissions simultaneously.…”

Combustion noise characterization and optimization of PCCI combustion using response surface methodology

“…These combustion concepts also suffer from high combustion noise, limited operating range and high cycle-to-cycle variations [4][5][6]. Many technical solutions, such as alternative fuels, multiple split injections and optimized engine parameters, are proposed to reduce the drawbacks in PCCI combustion [7][8][9][10]. To anticipate and improve the operating parameters of diesel engines, a variety of techniques are used, including response surface methodology (RSM), Taguchi-Grey relational analysis, genetic algorithms, particle swarm optimization, artificial neural networks, and fuzzy logic [11][12][13].…”