Effect of fuel injection parameters on combustion stability and emissions of a mineral diesel fueled partially premixed charge compression ignition (PCCI) engine

In the last decade, advanced combustion techniques of the low-temperature combustion (LTC) family have attracted researchers because of their excellent emission characteristics; however, combustion control remains the main issue for the LTC modes. The objective of this study was to explore premixed charge compression ignition (PCCI) combustion mode using a double pilot injection (DPI; pilot-pilot-main) strategy to achieve superior combustion control and to tackle the soot-oxides of nitrogen (NOx) trade-off. Experiments were carried out in a single-cylinder research engine fueled with 20% v/v biodiesel blended with mineral diesel (B20) and 40% v/v biodiesel blended with mineral diesel (B40) vis-à-vis baseline mineral diesel. Engine speed and rate of fuel-mass injected were maintained constant at 1500 rpm and 0.6 kg/h mineral diesel equivalent, respectively. Pilot injection timings (at 45° and 35° before top dead center (bTDC)) and fuel quantities were fixed, while three fuel injection pressures (FIPs) and four different start of the main injection (SoMI) timings were investigated in this study. Results showed that multiple pilot injections resulted in a stable PCCI combustion mode, making it suitable for higher engine loads. For all test fuels, advancing SoMI timings led to relatively lesser knocking; however, engine performance characteristics degraded at advanced SoMI timings. B40 exhibited relatively superior engine performance among different test fuels at lower FIP; however, the difference in engine performance was insignificant at higher FIPs. Fuel injection parameters showed a significant effect on emissions, especially on the NOx and particulates. Advancing SoMI timing resulted in 20%–50% lower particulates emissions with a slight NOx increase; however, the differences in emissions at different SoMI timings reduced at higher FIPs. Somewhat higher particulates from biodiesel blends were a critical observation of this study, which was more dominant at advanced SoMI timings. Qualitative correlation between NOx-total particulate mass (TPM) was another critical analysis, which exhibited the relative importance of different fuel injection parameters for other alternative fuels. Overall, B20 at 700 bar FIP and 20° SoMI timing emerged as the most promising proposition with some penalty in CO emission.

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Effects of Fuel Injection Parameters on Low Temperature Diesel Combustion Stability

10.4271/2010-01-0611 ◽

2010 ◽

Cited By ~ 7

Author(s):

Shenghui Cong ◽

Gordon McTaggart-Cowan ◽

Colin Garner

Keyword(s):

Low Temperature ◽

Fuel Injection ◽

Combustion Stability ◽

Diesel Combustion ◽

Injection Parameters

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Fuel Stratification and Partially Premixed Combustion With Neat n-Butanol in a Compression Ignition Engine

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4040517 ◽

2018 ◽

Vol 140 (12) ◽

Cited By ~ 3

Author(s):

Shouvik Dev ◽

Tongyang Gao ◽

Xiao Yu ◽

Mark Ives ◽

Ming Zheng

Keyword(s):

Fuel Injection ◽

Direct Injection ◽

Premixed Combustion ◽

Injection Timing ◽

Compression Ignition ◽

Compression Ignition Engine ◽

Fuel Stratification ◽

Partially Premixed Combustion ◽

Partially Premixed ◽

Ci Engines

Homogeneous charge compression ignition (HCCI) has been considered as an ideal combustion mode for compression ignition (CI) engines due to its superb thermal efficiency and low emissions of nitrogen oxides (NOx) and particulate matter. However, a challenge that limits practical applications of HCCI is the lack of control over the combustion rate. Fuel stratification and partially premixed combustion (PPC) have considerably improved the control over the heat release profile with modulations of the ratio between premixed fuel and directly injected fuel, as well as injection timing for ignition initiation. It leverages the advantages of both conventional direct injection compression ignition and HCCI. In this study, neat n-butanol is employed to generate the fuel stratification and PPC in a single cylinder CI engine. A fuel such as n-butanol can provide additional benefits of even lower emissions and can potentially lead to a reduced carbon footprint and improved energy security if produced appropriately from biomass sources. Intake port fuel injection (PFI) of neat n-butanol is used for the delivery of the premixed fuel, while the direct injection (DI) of neat n-butanol is applied to generate the fuel stratification. Effects of PFI-DI fuel ratio, DI timing, and intake pressure on the combustion are studied in detail. Different conditions are identified at which clean and efficient combustion can be achieved at a baseline load of 6 bar IMEP. An extended load of 14 bar IMEP is demonstrated using stratified combustion with combustion phasing control.

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Performance and Emission Analysis of Partially Premixed Charge Compression Ignition Combustion

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4042334 ◽

2019 ◽

Vol 141 (6) ◽

Author(s):

Charu Vikram Srivatsa ◽

Jonathan Mattson ◽

Christopher Depcik

Keyword(s):

Compression Ratio ◽

Fuel Injection ◽

Load Condition ◽

Injection System ◽

Compression Ignition ◽

High Compression Ratio ◽

High Compression ◽

Ci Engine ◽

Partially Premixed ◽

Load Conditions

In order to investigate the performance and emissions behavior of a high compression ratio compression ignition (CI) engine operating in partially premixed charge compression ignition (PPCI) mode, a series of experiments were conducted using a single-cylinder engine with a high-pressure rail fuel injection system. This included a moderately advanced direct injection strategy to attempt PPCI combustion under low load conditions by varying the injection timing between 25 deg and 35 deg before top dead center (BTDC) in steps of 2.5 deg. Furthermore, during experimentation the fuel injection pressure, engine speed, and engine torque were kept constant. Performance parameters and emissions were measured and analyzed using a zero-dimensional heat release model. Compared to the baseline conventional 12.5 deg BTDC injection, in-cylinder pressure and temperature were higher at advanced timings for all load conditions considered. Additionally, NOx, PM, CO, and total hydrocarbon (THC) were higher than conventional results at the 0.5 N·m load condition. While PM emissions were lower, and CO and THC emissions were comparable to conventional injection results at the 1.5 N·m load condition between 25 deg and 30 deg BTDC, NOx emissions were relatively high. Hence, there was limited success in beating the NOx-PM trade-off. Moreover, since the start of combustion (SOC) occurred BTDC, the resulting higher peak combustion pressures restricted the operating condition to lower loads. As a result, further investigation including exhaust gas recirculation (EGR) and/or variance in fuel cetane number (CN) is required to achieve PPCI in a high compression ratio CI engine.

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