scholarly journals A Numerical Analysis of the Effects of Equivalence Ratio Measurement Accuracy on the Engine Efficiency and Emissions at Varied Compression Ratios

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1413
Author(s):  
Ruomiao Yang ◽  
Xiaoxia Sun ◽  
Zhentao Liu ◽  
Yu Zhang ◽  
Jiahong Fu
Keyword(s):  
Compression Ratio ◽  
Thermal Efficiency ◽  
Equivalence Ratio ◽  
Measurement Accuracy ◽  
High Compression Ratio ◽  
Engine Efficiency ◽  
Fuel Ratio ◽  
High Compression ◽  
Performance And Emissions ◽  
Engine Stability

Increasingly stringent regulations to reduce vehicle emissions have made it important to study emission mitigation strategies. Highly accurate control of the air-fuel ratio is an effective way to reduce emissions. However, a less accurate sensor can lead to reduced engine stability and greater variability in engine efficiency and emissions. Additionally, internal combustion engines (ICE) are moving toward higher compression ratios to achieve higher thermal efficiency and alleviate the energy crisis. The objective of this investigation was to analyze the significance of the accuracy of air-fuel ratio measurements at different compression ratios. In this study, a calibrated 1D CFD model was used to analyze the performance and emissions at different compression ratios. The results showed that carbon monoxide (CO) and nitrogen oxides (NOx) were sensitive to the equivalence ratio regardless of the compression ratio. With a slight change in the equivalence ratio, a high compression ratio had little effect on the change in engine performance and emissions. Moreover, with the same air-fuel ratio, an excessively high compression ratio (CR = 12) might result in knocking phenomenon, which increases the fluctuation of the engine output parameters and reduces engine stability. Overall, for precise control of combustion and thermal efficiency improvement, it is recommended that the measurement accuracy of the equivalence ratio is higher than 1% and the recommended value of the compression ratio are roughly 11.

Comparing methods for improving spark-ignited engine efficiency: Over-expansion with multi-link cranktrain and high compression ratio with late intake valve closing

2020 ◽  
Vol 262 ◽  
pp. 114560 ◽  
Author(s):  
Zhuyong Yang ◽  
Niranjan Miganakallu ◽  
Tyler Miller ◽  
Jeremy Worm ◽  
Jeffrey Naber ◽  
...  
Keyword(s):  
Compression Ratio ◽  
Intake Valve ◽  
High Compression Ratio ◽  
Engine Efficiency ◽  
High Compression

An Investigation Into OME3 on a High Compression Ratio Engine

2020 ◽  
Author(s):  
Simon LeBlanc ◽  
Navjot Sandhu ◽  
Xiao Yu ◽  
Xiaoye Han ◽  
Meiping Wang ◽  
...  
Keyword(s):  
Compression Ratio ◽  
Alternative Fuels ◽  
Cetane Number ◽  
Engine Performance ◽  
High Compression Ratio ◽  
Engine Efficiency ◽  
High Compression ◽  
Combustion Emissions ◽  
Soot Emissions ◽  
Chain Lengths

Abstract For decades, alternative fuels have been studied to further engine efficiency and lower combustion emissions. Of these fuels, biodiesel, alcohols, and ethers have shown advantageous benefits of improved mixing capability or reduced combustion emissions. Ether fuels consist of a range of C-O-C chain lengths that offer various noteworthy fuel properties such as fuel oxygen content and cetane number. In this work, oxymethylene dimethyl ether (OME3) and diesel are used as neat and blended fuels on a single-cylinder high compression ratio engine. Four test fuels are investigated in this work; baseline diesel, two diesel/OME3 blends, and neat OME3 fuel. Engine tests are conducted at an engine load of 6 bar and the intake oxygen concentration is modulated via EGR to realize the resulting engine performance, stability, and exhaust emissions among the test fuels. The results show that blending OME3 fuels with diesel is an effective technique to reduce soot emissions with minimal effect on NOx emissions. Moreover, neat OME3 was capable of emitting low NOx and soot emissions with a lower EGR amount than that of diesel-blends, mitigating negative combustion implication of EGR at high levels.

Improvement of Thermal Efficiency and NOx Emissions by High Compression Ratio Combustion in a DI Diesel Engine

2004 ◽  
Vol 2004.3 (0) ◽  
pp. 131-132
Author(s):  
Yusuke NAKAHIRA ◽  
Takashi OZAWA ◽  
Hidekatsu TSUTSUMI ◽  
Masahiro ONODERA ◽  
Koji IMOTO
Keyword(s):  
Diesel Engine ◽  
Compression Ratio ◽  
Thermal Efficiency ◽  
Nox Emissions ◽  
High Compression Ratio ◽  
High Compression ◽  
Di Diesel Engine

Performance and Emissions Analysis of Partially Pre-Mixed Charge Compression Ignition Combustion

2018 ◽  
Author(s):  
Charu Vikram Srivatsa ◽  
Jonathan Mattson ◽  
Christopher Depcik
Keyword(s):  
Compression Ratio ◽  
Fuel Injection ◽  
Load Condition ◽  
Compression Ignition ◽  
Cylinder Pressure ◽  
High Compression Ratio ◽  
High Compression ◽  
Performance And Emissions ◽  
Ci Engine ◽  
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 naturally aspirated 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° and 35° Before Top Dead Center (BTDC) in steps of 2.5°. Furthermore, during experimentation the fuel injection pressure, engine speed, and engine torque (through variance of the fuel injection quantity) were kept constant. In-cylinder pressure, emissions, and performance parameters were measured and analyzed using a zero-dimensional heat release model. Compared to the baseline conventional 12.5° BTDC injection, in-cylinder pressure and temperature was higher at advanced timings for all load conditions considered. Additionally, NOx, PM, CO, and 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° and 30° BTDC, NOx emissions were relatively high. Hence, there was limited success in beating the NOx-PM tradeoff. In addition, since Start of Combustion (SOC) occurred BTDC, the resulting higher peak combustion pressures restricted the operating condition to lower loads to ensure engine safety. 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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