Hybrid Robust Control for Engines Running Low Temperature Combustion and Conventional Diesel Combustion Modes

In order to meet future emissions regulations, new combustion concepts are being developed. Among them, the development of low-temperature diesel combustion systems has received considerable attention. Low NOx emissions are achieved through minimization of peak temperatures during the combustion process. Concurrently, soot formation is inhibited due to a combination of low combustion temperatures and extensive fuel-air premixing. In this study, the effect of late-cycle mixing enhancement by post-injection strategies on combustion and engine-out emissions in the low-temperature (low soot and NOx emissions) combustion regime was experimentally investigated. The baseline operating condition considered for low-temperature combustion was 1500rpm, 3bar IMEP with 50% EGR rate, and extension to high loads was considered by means of post injection. Post-injection strategies gave very favorable emission results in the low-temperature combustion regime at all loads tested in this study. Since post injection leads to late-cycle mixing improvement, further reductions in soot emissions were achieved without deteriorating the NOx emissions. With smaller fuel injected amounts for the second pulse, better soot emissions were found. However, the determination of the dwell between the injections was found to be very important for the emissions.

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Study of Cylinder Charge Control for Enabling Low Temperature Combustion in Diesel Engines

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4026929 ◽

2014 ◽

Vol 136 (9) ◽

Cited By ~ 8

Author(s):

Prasad Divekar ◽

Usman Asad ◽

Xiaoye Han ◽

Xiang Chen ◽

Ming Zheng

Keyword(s):

Low Temperature ◽

Diesel Engines ◽

Direct Injection ◽

Flame Temperature ◽

Stable Operation ◽

Low Temperature Combustion ◽

Multiple Control ◽

Engine Load ◽

Combustion Modes ◽

Temperature Combustion

Suitable cylinder charge preparation is deemed critical for the attainment of a highly homogeneous, diluted, and lean cylinder charge, which is shown to lower the flame temperature. The resultant low temperature combustion (LTC) can simultaneously reduce the NOx and soot emissions from diesel engines. This requires sophisticated coordination of multiple control systems for controlling the intake boost, exhaust gas recirculation (EGR), and fueling events. Additionally, the cylinder charge modulation becomes more complicated in the novel combustion concepts that apply port injection of low reactivity alcohol fuels to replace the diesel fuel partially or entirely. In this work, experiments have been conducted on a single cylinder research engine with diesel and ethanol fuels. The test platform is capable of independently controlling the intake boost, EGR rates, and fueling events. Effects of these control variables are evaluated with diesel direct injection and a combination of diesel direct injection and ethanol port injection. Data analyses are performed to establish the control requirements for stable operation at different engine load levels with the use of one or two fuels. The sensitivity of the combustion modes is thereby analyzed with regard to the boost, EGR, fuel types, and fueling strategies. Zero-dimensional cycle simulations have been conducted in parallel with the experiments to evaluate the operating requirements and operation zones of the LTC combustion modes. Correlations are generated between air–fuel ratio (λ), EGR rate, boost level, in-cylinder oxygen concentration, and load level using the experimental data and simulation results. Development of a real-time boost-EGR set-point determination to sustain the LTC mode at the varying engine load levels and fueling strategies is proposed.

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An Experimental and Numerical Investigation on the Effect of Post Injection Strategies on Combustion and Emissions in the Low-Temperature Diesel Combustion Regime

ASME 2005 Internal Combustion Engine Division Spring Technical Conference ◽

10.1115/ices2005-1043 ◽

2005 ◽

Cited By ~ 12

Author(s):

Hanho Yun ◽

Yong Sun ◽

Rolf D. Reitz

Keyword(s):

Low Temperature ◽

Soot Formation ◽

Combustion Regime ◽

Nox Emissions ◽

Diesel Combustion ◽

Low Temperature Combustion ◽

Post Injection ◽

Temperature Combustion ◽

Soot Emissions ◽

Injection Strategies

In order to meet future emissions regulations, new combustion concepts are being developed. Among them, the development of low-temperature diesel combustion systems has received considerable attention. Low NOx emissions are achieved through minimization of peak temperatures occurring during the combustion process. Concurrently, soot formation is inhibited due to a combination of low combustion temperatures and extensive fuel-air pre-mixing. In this study, the effect of late-cycle mixing enhancement by post injection strategies on combustion and engine-out emissions in the low-temperature combustion regime was investigated experimentally and numerically. The baseline operating condition considered for low-temperature combustion was 1500 rev/min, 3bar IMEP with 50% EGR rate, and extension to high loads was considered by means of post injection. Post injection strategies gave very favorable emission results in the low temperature combustion regime at all loads. With small second fuel injected amounts, better soot emissions were found. However, the determination of the dwell between the injections was found to be very important for the emissions. Since post injection leads to late-cycle mixing improvement, further reductions in soot emissions were achieved without deteriorating the NOx emissions. To explain these results, numerical analysis was also done using the KIVA-CHEMKIN code. The simulations show that optimal combustion requires that the post injection fuel avoid fuel rich regions formed from the main injection.

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Single-cylinder engine evaluation of a multi-component Diesel surrogate fuel at partially-premixed and low-temperature combustion modes

Fuel ◽

10.1016/j.fuel.2018.12.073 ◽

2019 ◽

Vol 241 ◽

pp. 506-518 ◽

Cited By ~ 6

Author(s):

Patrick G. Szymkowicz ◽

Jesús Benajes

Keyword(s):

Low Temperature ◽

Low Temperature Combustion ◽

Single Cylinder ◽

Single Cylinder Engine ◽

Combustion Modes ◽

Temperature Combustion ◽

Partially Premixed ◽

Surrogate Fuel

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Study of Cylinder Charge Control for Enabling Low Temperature Combustion in Diesel Engines

Volume 1: Large Bore Engines; Advanced Combustion; Emissions Control Systems; Instrumentation, Controls, and Hybrids ◽

10.1115/icef2013-19226 ◽

2013 ◽

Cited By ~ 5

Author(s):

Prasad Divekar ◽

Usman Asad ◽

Xiaoye Han ◽

Xiang Chen ◽

Ming Zheng

Keyword(s):

Low Temperature ◽

Diesel Engines ◽

Direct Injection ◽

Flame Temperature ◽

Stable Operation ◽

Low Temperature Combustion ◽

Multiple Control ◽

Engine Load ◽

Combustion Modes ◽

Temperature Combustion

Suitable cylinder charge preparation is deemed critical for the attainment of a highly homogeneous, diluted, and lean cylinder charge which is shown to lower the flame temperature. The resultant low temperature combustion (LTC) can simultaneously reduce the NOx and soot emissions from diesel engines. This requires sophisticated coordination of multiple control systems for controlling the intake boost, exhaust gas recirculation (EGR), and fueling events. Additionally, the cylinder charge modulation becomes more complicated in the novel combustion concepts that apply port injection of low reactivity alcohol fuels to replace the diesel fuel partially or entirely. In this work, experiments have been conducted on a single cylinder research engine with diesel and ethanol fuels. The test platform is capable of independently controlling the intake boost, EGR rates, and fuelling events. Effects of these control variables are evaluated with diesel direct injection and a combination of diesel direct injection and ethanol port injection. Data analyses are performed to establish the control requirements for stable operation at different engine load levels with the use of one or two fuels. The sensitivity of the combustion modes is thereby analyzed with regard to the boost, EGR, fuel types and fueling strategies. Zero-dimensional cycle simulations have been conducted in parallel with the experiments to evaluate the operating requirements and operation zones of the LTC combustion modes. Correlations are generated between air-fuel ratio (λ), EGR rate, boost level, in-cylinder oxygen concentration and load level using the experimental data and simulation results. Development of a real-time boost-EGR set-point determination to sustain the LTC mode at the varying engine load levels and fueling strategies is proposed.

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