Fuel reactivity controlled compression ignition (RCCI): a pathway to controlled high-efficiency clean combustion

Reactivity-controlled compression ignition (RCCI) is a dual-fuel variant of low-temperature combustion that uses in-cylinder fuel stratification to control the rate of reactions occurring during combustion. Using fuels of varying reactivity (autoignition propensity), gradients of reactivity can be established within the charge, allowing for control over combustion phasing and duration for high efficiency while achieving low NOx and soot emissions. In practice, this is typically accomplished by premixing a low-reactivity fuel, such as gasoline, with early port or direct injection, and by direct injecting a high-reactivity fuel, such as diesel, at an intermediate timing before top dead center. Both the relative quantity and the timing of the injection(s) of high-reactivity fuel can be used to tailor the combustion process and thereby the efficiency and emissions under RCCI. While many combinations of high- and low-reactivity fuels have been successfully demonstrated to enable RCCI, there is a lack of fundamental understanding of what properties, chemical or physical, are most important or desirable for extending operation to both lower and higher loads and reducing emissions of unreacted fuel and CO. This is partly due to the fact that important variables such as temperature, equivalence ratio, and reactivity change simultaneously in both a local and a global sense with changes in the injection of the high-reactivity fuel. This study uses primary reference fuels iso-octane and n-heptane, which have similar physical properties but much different autoignition properties, to create both external and in-cylinder fuel blends that allow for the effects of reactivity stratification to be isolated and quantified. This study is part of a collaborative effort with researchers at Sandia National Laboratories who are investigating the same fuels and conditions of interest in an optical engine. This collaboration aims to improve our fundamental understanding of what fuel properties are required to further develop advanced combustion modes.

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Investigation of Combustion Phasing Control Strategy During Reactivity Controlled Compression Ignition (RCCI) Multicylinder Engine Load Transitions

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4027190 ◽

2014 ◽

Vol 136 (9) ◽

Cited By ~ 28

Author(s):

Yifeng Wu ◽

Reed Hanson ◽

Rolf D. Reitz

Keyword(s):

Steady State ◽

Control Strategy ◽

High Efficiency ◽

Operating Conditions ◽

Intake Manifold ◽

Injection Timing ◽

Compression Ignition ◽

Reactivity Controlled Compression Ignition ◽

Phasing Control ◽

Intake Manifold Pressure

The dual fuel reactivity controlled compression ignition (RCCI) concept has been successfully demonstrated to be a promising, more controllable, high efficiency, and cleaner combustion mode. A multidimensional computational fluid dynamics (CFD) code coupled with detailed chemistry, KIVA-CHEMKIN, was applied to develop a strategy for phasing control during load transitions. Steady-state operating points at 1500 rev/min were calibrated from 0 to 5 bar brake mean effective pressure (BMEP). The load transitions considered in this study included a load-up and a load-down load change transient between 1 bar and 4 bar BMEP at 1500 rev/min. The experimental results showed that during the load transitions, the diesel injection timing responded in two cycles while around five cycles were needed for the diesel common-rail pressure to reach the target value. However, the intake manifold pressure lagged behind the pedal change for about 50 cycles due to the slower response of the turbocharger. The effect of these transients on RCCI engine combustion phasing was studied. The CFD model was first validated against steady-state experimental data at 1 bar and 4 bar BMEP. Then the model was used to develop strategies for phasing control by changing the direct port fuel injection (PFI) amount during load transitions. Specific engine operating cycles during the load transitions (six cycles for the load-up transition and seven cycles for the load-down transition) were selected based on the change of intake manifold pressure to represent the transition processes. Each cycle was studied separately to find the correct PFI to diesel fuel ratio for the desired CA50 (the crank angle at which 50% of total heat release occurs). The simulation results showed that CA50 was delayed by 7 to 15 deg for the load-up transition and advanced by around 5 deg during the load-down transition if the precalibrated steady-state PFI table was used. By decreasing the PFI ratio by 10% to 15% during the load-up transition and increasing the PFI ratio by around 40% during the load-down transition, the CA50 could be controlled at a reasonable value during transitions. The control strategy can be used for closed-loop control during engine transient operating conditions. Combustion and emission results during load transitions are also discussed.

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Reactivity Controlled Compression Ignition Performance With Renewable Fuels

ASME 2012 Internal Combustion Engine Division Fall Technical Conference ◽

10.1115/icef2012-92192 ◽

2012 ◽

Cited By ~ 8

Author(s):

Scott J. Curran ◽

James P. Szybist ◽

Robert M. Wagner

Keyword(s):

High Efficiency ◽

Fuel Injection ◽

Combustion Process ◽

Renewable Fuels ◽

Compression Ignition ◽

Reactivity Controlled Compression Ignition ◽

Engine Efficiency ◽

Fuel Charge ◽

Performance And Emissions ◽

Ethanol Blends

Reactivity controlled compression ignition (RCCI) combustion makes use of in-cylinder blending of two fuels with differing reactivity to tailor the reactivity of the fuel charge for improved control of the combustion process. This approach has been shown in simulations and engine experiments to have the potential for high efficiency with very low NOX and particulate matter (PM) emissions. Previous multi-cylinder RCCI experiments have been completed to understand the potential of this approach under more real-world conditions in a light-duty multi-cylinder engine (MCE) with production viable hardware. MCE experiments explored fuel injection strategy, dilution levels, piston geometry (including compression ratio), and fuel properties. Many renewable fuels have unique properties which enable expanded operation of advanced combustion methods for higher engine efficiency and lower energy requirements for emissions control devices. This study investigates the effect that renewable gasoline and diesel fuel replacements have on the load-expansion of RCCI, performance and emissions. The study focuses on ethanol blends for replacement of gasoline as the port-injected fuel (PFI) and biodiesel blends as the replacement for the direct injected (DI) fuel.

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Review of high efficiency and clean reactivity controlled compression ignition (RCCI) combustion in internal combustion engines

Progress in Energy and Combustion Science ◽

10.1016/j.pecs.2014.05.003 ◽

2015 ◽

Vol 46 ◽

pp. 12-71 ◽

Cited By ~ 548

Author(s):

Rolf D. Reitz ◽

Ganesh Duraisamy

Keyword(s):

Internal Combustion Engines ◽

High Efficiency ◽

Internal Combustion ◽

Combustion Engines ◽

Compression Ignition ◽

Reactivity Controlled Compression Ignition

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Clean combustion and emissions strategy using reactivity controlled compression ignition (RCCI) mode engine powered with CNG-Karanja biodiesel

Journal of the Taiwan Institute of Chemical Engineers ◽

10.1016/j.jtice.2021.04.055 ◽

2021 ◽

Author(s):

S.P. Wategave ◽

N.R. Banapurmath ◽

M.S. Sawant ◽

Manzoore Elahi M. Soudagar ◽

M.A. Mujtaba ◽

...

Keyword(s):

Compression Ignition ◽

Reactivity Controlled Compression Ignition ◽

Clean Combustion

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Improving high efficiency reactivity controlled compression ignition combustion with diesel and gasoline direct injection

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1177/0954407012456123 ◽

2012 ◽

Vol 227 (1) ◽

pp. 17-30 ◽

Cited By ~ 18

Author(s):

Jae Hyung Lim ◽

Rolf Reitz

Keyword(s):

High Efficiency ◽

Direct Injection ◽

Gasoline Direct Injection ◽

Compression Ignition ◽

Reactivity Controlled Compression Ignition ◽

Compression Ignition Combustion

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Investigation of Combustion Phasing Control Strategy During Reactivity Controlled Compression Ignition (RCCI) Multi-Cylinder Engine Load Transitions

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

10.1115/icef2013-19195 ◽

2013 ◽

Author(s):

Yifeng Wu ◽

Reed Hanson ◽

Rolf D. Reitz

Keyword(s):

Steady State ◽

Control Strategy ◽

High Efficiency ◽

Operating Conditions ◽

Intake Manifold ◽

Injection Timing ◽

Compression Ignition ◽

Reactivity Controlled Compression Ignition ◽

Phasing Control ◽

Intake Manifold Pressure

The dual fuel reactivity controlled compression ignition (RCCI) concept has been successfully demonstrated to be a promising, more controllable, high efficiency and cleaner combustion mode. A multi-dimensional computational fluid dynamics (CFD) code coupled with detailed chemistry, KIVA-CHEMKIN, was applied to develop a strategy for phasing control during load transitions. Steady-state operating points at 1500 rev/min were calibrated from 0 to 5 bar brake mean effective pressure (BMEP). The load transitions considered in this study included a load-up and a load-down load change transient between 1 bar and 4 bar BMEP at 1500 rev/min. The experimental results showed that during the load transitions, the diesel injection timing responded in 2 cycles while around 5 cycles were needed for the diesel common-rail pressure to reach the target value. However, the intake manifold pressure lagged behind the pedal change for about 50 cycles due to the slower response of the turbocharger. The effect of these transients on RCCI engine combustion phasing was studied. The CFD model was first validated against steady-state experimental data at 1 bar and 4 bar BMEP. Then the model was used to develop strategies for phasing control by changing the direct port fuel injection (PFI) amount during load transitions. Specific engine operating cycles during the load transitions (6 cycles for the load-up transition and 7 cycles for the load-down transition) were selected based on the change of intake manifold pressure to represent the transition processes. Each cycle was studied separately to find the correct PFI to diesel fuel ratio for the desired CA50 (the crank angle at which 50 % of total heat release occurs). The simulation results showed that CA50 was delayed by 7 to 15 degrees for the load-up transition and advanced by around 5 degrees during the load-down transition if the pre-calibrated steady-state PFI table was used. By decreasing the PFI ratio by 10 % to 15 % during the load-up transition and increasing the PFI ratio by around 40 % during the load-down transition, the CA50 could be controlled at a reasonable value during transitions. The control strategy can be used for closed-loop control during engine transient operating conditions. Combustion and emission results during load transitions are also discussed.

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