scholarly journals Mechanism of Combustion Noise Influenced by Pilot Injection in PPCI Diesel Engines

2019 ◽  
Vol 9 (9) ◽  
pp. 1875 ◽  
Author(s):  
Jingtao Du ◽  
Ximing Chen ◽  
Long Liu ◽  
Dai Liu ◽  
Xiuzhen Ma
Keyword(s):  
Diesel Engines ◽  
Wavelet Transforms ◽  
Wavelet Packet ◽  
Combustion Noise ◽  
Pilot Injection ◽  
Injection Parameters ◽  
Emission Regulations ◽  
Main Injection ◽  
Simultaneous Decrease ◽  
Gas Recirculation

Pilot injection combined with exhaust gas recirculation (EGR) is usually utilized to realize the partially premixed compression ignition (PPCI) mode in diesel engines, which enables the simultaneous decrease of nitrogen oxide and soot emissions to satisfy emission regulations. Moreover, the ignition delay of main injection combustion can also be shortened by pilot injection, and then combustion noise is reduced. Nevertheless, the mechanisms of pilot injection impacts on combustion noise are not completely understood. As such, it is hard to optimize pilot injection parameters to minimize combustion noise. Therefore, experiments were conducted on a four-stroke single-cylinder diesel engine with different pilot injection strategies and 20% EGR as part of an investigation into this relationship. Firstly, the combustion noise was analyzed by cylinder pressure levels (CPLs). Then, the stationary wavelet transforms (SWTs) and stationary wavelet packet transform (SWPT) were employed to decompose in-cylinder pressures at different scales, and thus the combustion noise generated by pilot and main combustion was investigated in both the time and frequency domain. The results show that pilot injection is dominant in the high frequency segment of combustion noise, and main injection has a major impact on combustion noise in the low and mid frequency segment. Finally, the effects of various pilot injection parameters on suppressing combustion noise were analyzed in detail.

Preinjection—A Measure to Influence Exhaust Quality and Noise in Diesel Engines

1989 ◽  
Vol 111 (3) ◽  
pp. 445-450 ◽  
Author(s):  
H. Schulte ◽  
E. Scheid ◽  
F. Pischinger ◽  
U. Reuter
Keyword(s):  
Diesel Engines ◽  
High Speed ◽  
Combustion Noise ◽  
Injection System ◽  
Pilot Injection ◽  
Load Range ◽  
Injection Nozzle ◽  
Black Smoke ◽  
Injection Quantity ◽  
Main Injection

The combustion noise generated by DI diesel engines can be clearly reduced during both steady-state and transient operation in applying a pilot injection. After optimization, a slight increase in fuel consumption is found in the upper load range. The pilot injection also tends to reduce the NOx emissions. An increase in black smoke emissions is considered to be the main drawback with pilot injection. High-speed Schlieren photographs of injection and combustion phenomena within a pressurized chamber show that the higher black smoke emissions may be due to the combustion of the main injection quantity that occurs in a mixture that is insufficiently prepared and with nearly no delay due to the pilot injection. On the basis of these findings, it is concluded that a high degree of atomization and rapid vaporization of the main injection quantity must be accomplished. To achieve these goals better, a separate injection nozzle for the pilot quantity is preferred to an injection system with a single injection nozzle, providing both the pilot and the main quantity. Therefore, rather simple injection systems with a separate pilot injector can be developed that provide a constant pilot quantity and controlled pilot injection time over the entire engine map.

Analysis of Pilot Injection Effects on Combustion Noise in PPCI Diesel Engines

2016 ◽  
Author(s):  
Long Liu ◽  
Hongzi Fei ◽  
Jingtao Du
Keyword(s):  
Diesel Engines ◽  
High Frequency ◽  
Combustion Process ◽  
High Load ◽  
Operating Conditions ◽  
Combustion Noise ◽  
Pilot Injection ◽  
Injection Strategy ◽  
Injection Quantity ◽  
Main Injection

With the common-rail fuel injection systems widely used in diesel engines, the pilot injection strategy has been paid more attention for suppressing pollutants emissions and combustion noise. Using pilot injection strategies, leaner and more homogenous mixture formed in pilot spray results in the combustion process partially fulfill Premixed Charge Compression Ignition (PCCI). Therefore the combustion process of diesel engines with pilot injection strategy can be considered as partial PCCI (PPCI). Pilot injection causes the in-cylinder temperature increase before main injection, which shortens the ignition delay of main spray and consequently reduces the combustion noise, so that the pilot injection has potential to extend PPCI combustion model to high load operation. However, the mechanism of pilot injection effects on the combustion noise has not been fully understood, consequently it is difficult to estimate the lower combustion noise among different pilot injection conditions, that results in difficult selection of the pilot injection parameters in proper way. Thus, in this study, experiments were performed on a single-cylinder DI-diesel engine with pilot and main injection under high load operating conditions. The synthesized in-cylinder pressure levels (CPLs) in different frequency ranges as a novel method were proposed to analyze the pilot injection effects on combustion noise. The results reveal that pilot spray combustion mainly influences the high frequency combustion noise, and the later pilot injection timing causes the higher combustion noise. In the case of the short dwell between pilot and main injection, the increasing pilot injection quantity enhances the high frequency combustion noise. Meanwhile because of the pilot injection quantity increase, decrease of main injection quantity leads to lower combustion noise in middle frequency range.

scholarly journals Sensitivity of combustion noise and NOx and soot emissions to pilot injection in PCCI Diesel engines

2013 ◽  
Vol 104 ◽  
pp. 149-157 ◽  
Author(s):  
A.J. Torregrosa ◽  
A. Broatch ◽  
A. García ◽  
L.F. Mónico
Keyword(s):  
Diesel Engines ◽  
Combustion Noise ◽  
Pilot Injection ◽  
Soot Emissions

scholarly journals The Influence of Common-rail Adjustment on the Parameters of a Diesel Tractor Engine

2016 ◽  
Vol 64 (3) ◽  
pp. 911-918 ◽  
Author(s):  
Lukáš Tunka ◽  
Adam Polcar
Keyword(s):  
Noise Level ◽  
Common Rail ◽  
Combustion Noise ◽  
Injection System ◽  
Pilot Injection ◽  
Fuel System ◽  
Rail Pressure ◽  
Common Rail Injection System ◽  
Main Injection ◽  
Tractor Engine

The article deals with the issue of high-pressure indication of a diesel tractor engine Z 1727, which was fitted with a modern electronically controlled common-rail injection system. The aim of the study is to evaluate the influence of the adjustment of the fuel system – start of injection (SOI) timings and the rail pressure (PRAIL) – on the pressure development in the cylinder (PCYL), the heat release (HR) and the combustion noise level (CNLA). Furthermore, the article examines the influence of pilot and post fuel injections on the CNLA. The experiments were conducted at constant speed (1480 rpm) with four PRAILs and different SOI timings. As the results of measurements have shown, higher rail pressure causes higher pressure and a release of a larger amount of heat in the cylinder. These two parameters are the basic prerequisite for higher engine efficiency – higher power output of the engine at lower fuel consumption and decreased production of harmful emissions. Other advantages of the common-rail fuel system include the potential of dividing the main injection dose into the pilot injection and main injection, as well as the potential post injection. The measurements have further demonstrated that including a pilot injection phase significantly contributes to a decrease in combustion noise level as well as a more even, quieter operation of the engine.

Closed-Loop Control Framework for Fuel-Flexible Combustion of Biodiesel Blends

2010 ◽  
Author(s):  
David B. Snyder ◽  
Gayatri H. Adi ◽  
Carrie M. Hall ◽  
Michael P. Bunce ◽  
Gregory M. Shaver
Keyword(s):  
Closed Loop ◽  
Combustion Noise ◽  
Injection Timing ◽  
Closed Loop Control ◽  
Loop Control ◽  
Biodiesel Blends ◽  
Control Framework ◽  
Main Injection ◽  
Recirculation Fraction ◽  
Gas Recirculation

This paper presents a closed-loop control framework for fuel-flexible combustion control of biodiesel blends. This framework consists of two parts: blend detection and blend accommodation. Blend detection can be accomplished by an experimentally-validated dynamic estimator using exhaust oxygen and air-fuel ratio information. Blend accommodation can be accomplished by changing the control variables that the engine control module uses, namely, replacing exhaust gas recirculation fraction with combustible oxygen mass fraction, replacing total injected fuel mass with total injected fuel energy, and replacing start of main injection timing with end of main injection timing. With the conventional control structure it is experimentally shown that pure biodiesel (B100) produced 38% more brake specific nitrogen oxides (BSNOx) than pure conventional diesel (B0). With the new proposed structure, B100 produced not only lower BSNOx than B0, but also higher torque, higher brake thermal efficiency, lower particulate matter, and lower combustion noise than B0. Comparable experimental results are also presented for B5 and B20 blends.

scholarly journals Impact of low NOx strategies on holistic emission reduction from a CI engine over transient conditions

2020 ◽  
pp. 146808742097388
Author(s):  
Adriaan van Niekerk ◽  
Benjamin Drew ◽  
Neil Larsen ◽  
Peter Kay
Keyword(s):  
Internal Combustion Engines ◽  
Fossil Fuels ◽  
Pilot Injection ◽  
Test Bed ◽  
Compression Ignition Engine ◽  
Fuel Blend ◽  
Wide Range ◽  
Main Injection ◽  
The Uk ◽  
Gas Recirculation

The use of biofuels to replace fossil fuels as well as more stringent emission regulations for internal combustion engines cause a challenge for the engine manufacturers to build engines that can cope with a wide range of fuels, but still offer low exhaust emissions with no detriment to performance. In this work a test bed with a compression ignition engine has been used to measure emissions when using a ternary fuel blend between diesel, biodiesel and ethanol together with exhuast gas recirculation (EGR) and different fuel delivery techniques. EGR with biofuels have the potential to significantly reduce NOx over conventional diesel combustion. The fuel used, B2E9 achieves a 10% renewable content as set out in the UK government’s Renewable Energy Directive. Most studies reported in the literature evaluates emissions reduction technologies by only changing one factor-at-a-time at steady state conditions. This paper addresses these issues and presents a methodology utilising a Central Composite Design (CCD) analysis to optimise four engine parameters which include EGR percentage, main injection SOI, pilot injection SOI and pilot injection open duration over a transient drive cycle (WLTP) which makes the results more applicable to real world driving conditions. The optimisation of the CCD showed that NOx emissions decreases by 25% when the maximum exhaust gas recirculation is set to 45%, the main injection is retarded by 2 CADs, the pilot injection dwell time is set to 21 CADs and 24% of the fuel is delivered through the pilot injection. CO emissions increase by approximately 47% as a result of the decrease in NOx emissions.

Reducing Engine-Out Emissions for Medium High Speed Diesel Engines: Influence of Injection Parameters

2009 ◽  
Author(s):  
Pieter Roels ◽  
Yves Sledsens ◽  
Sebastian Verhelst ◽  
Roger Sierens ◽  
Lieven Vervaeke
Keyword(s):  
Diesel Engines ◽  
High Speed ◽  
Injection Parameters ◽  
High Speed Diesel

Multiple fuel injection strategy for premixed charge compression ignition combustion engine using biodiesel blends

2022 ◽  
pp. 146808742110667
Author(s):  
Akhilendra Pratap Singh ◽  
Ashutosh Jena ◽  
Avinash Kumar Agarwal
Keyword(s):  
Alternative Fuels ◽  
Fuel Injection ◽  
Engine Performance ◽  
Pilot Injection ◽  
Compression Ignition ◽  
Combustion Control ◽  
Combustion Mode ◽  
Biodiesel Blends ◽  
Injection Parameters ◽  
Study Results

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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