Optical diagnostics on the reactivity controlled compression ignition (RCCI) with micro direct-injection strategy

2019 ◽  
Vol 37 (4) ◽  
pp. 4767-4775 ◽  
Author(s):  
Haifeng Liu ◽  
Qinglong Tang ◽  
Xingwang Ran ◽  
Xinghui Fang ◽  
Mingfa Yao
Keyword(s):  
Direct Injection ◽  
Optical Diagnostics ◽  
Compression Ignition ◽  
Reactivity Controlled Compression Ignition ◽  
Injection Strategy

An integrated effort of medium reactivity fuel, in-cylinder, and after-treatment strategies to demonstrate potential reduction in challenging emissions of reactivity controlled compression ignition combustion

2019 ◽  
Vol 234 (5) ◽  
pp. 1260-1278
Author(s):  
R Murugan ◽  
D Ganesh ◽  
G Nagarajan
Keyword(s):  
Carbon Monoxide ◽  
Direct Injection ◽  
Cetane Number ◽  
Combustion Process ◽  
Oxidation Catalyst ◽  
Compression Ignition ◽  
Reactivity Controlled Compression Ignition ◽  
Potential Reduction ◽  
Carbon Monoxide Emission ◽  
Compression Ignition Combustion

Previous studies on reactivity controlled compression ignition combustion indicated that, reducing the hydrocarbon and carbon monoxide emissions at low load conditions still remains a challenge because of lower in-cylinder temperatures due to lower global reactivity gradient and reduced oxidation process. Research in this direction has not been reported so far and with this motivation, an attempt has been made to increase the global reactivity gradient and oxidation of fuel–air mixture by converting the low reactivity fuel methanol into medium reactivity fuel. This is achieved by mixing high octane oxygenated fuel, methanol (Octane Number: 110), with an oxygenated better cetane and volatility fuels like polyoxymethylene dimethyl ether (Cetane Number: 78) and isobutanol (Cetane Number: 15). The medium reactivity fuel with multiple direct injection of diesel fuel timed the combustion of dual fuel–air mixture to avoid too late or too advanced combustion which are the prime factors in controlling the unburnt emissions in a low temperature combustion process. Four medium reactivity fuel samples, M80IB20, M60IB40, M90P10, and M80P20, on percentage volume basis have been prepared and tested on the modified on-road three-cylinder turbocharged common rail direct injection diesel engine to demonstrate higher indicated thermal efficiency and potential reduction in unburnt and oxides of nitrogen/particulate matter emissions from reactivity controlled compression ignition combustion. Experimental results show that, use of medium reactivity fuel with optimized diesel injection strategy resulted in 66% decrease in hydrocarbon emission and 74% decrease in carbon monoxide emission by enhancing the oxidation of fuel–air mixture at lower temperatures which is evidently noticed in the combustion characteristics. Further reduction in hydrocarbon and carbon monoxide emission of about 90% has been achieved by integrating the diesel oxidation catalyst with the engine.

Computational optimization of reactivity controlled compression ignition combustion to achieve high efficiency and clean combustion

2020 ◽  
pp. 146808742093173 ◽  
Author(s):  
Avilash Jain ◽  
Anand Krishnasamy ◽  
Pradeep V
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Fuel Injection ◽  
Direct Injection ◽  
Network Models ◽  
Compression Ignition ◽  
Neural Network Models ◽  
Reactivity Controlled Compression Ignition ◽  
Artificial Neural ◽  
Artificial Neural Network Models

One of the major limitations of reactivity controlled compression ignition is higher unburned hydrocarbon and carbon monoxide emissions and lower thermal efficiency at part load operating conditions. In the present study, a combined numerical approach using a commercial three-dimensional computational fluid dynamics code CONVERGE along with artificial neural network and genetic algorithm is presented to address the above limitation. A production light-duty diesel engine is modified to run in reactivity controlled compression ignition by replacing an existing mechanical fuel injection system with a flexible electronic port fuel injection and common rail direct injection systems. The injection schedules of port fuel injection and direct injection injectors are controlled using National Instruments port and direct injection driver modules. Upon validation of combustion and emission parameters, parametric investigations are carried out to establish the effects of direct-injected diesel fuel timing start of injection (SOI), premixed fuel ratio and intake charge temperature on the engine performance and emissions in reactivity controlled compression ignition. The results obtained show that the start of injection timing and intake charge temperature significantly influence combustion phasing, while the premixed fuel ratio controls mixture reactivity and combustion quality. By utilizing the data generated with the validated computational fluid dynamics models, the artificial neural network models are trained to predict the engine exhaust emissions and efficiency. The artificial neural network models for gross indicated efficiency and oxides of nitrogen (NOx) are then coupled with genetic algorithm to maximize gross indicated efficiency while keeping the NOx and soot emissions within Euro VI emission limits. By optimizing the start of injection timing, premixed fuel ratio and intake charge temperature simultaneously using the artificial neural network models coupled with genetic algorithm, 19% improvement in gross indicated efficiency, 60% and 64% reduction in hydrocarbon and carbon monoxide emissions, respectively, are obtained in reactivity controlled compression ignition compared to the baseline case.

Reactivity Controlled Compression Ignition Using Premixed Hydrated Ethanol and Direct Injection Diesel

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Adam B. Dempsey ◽  
Bishwadipa Das Adhikary ◽  
Sandeep Viswanathan ◽  
Rolf D. Reitz
Keyword(s):  
Direct Injection ◽  
Fuel Efficiency ◽  
High Reactivity ◽  
Water Mixture ◽  
Compression Ignition ◽  
Load Range ◽  
Reactivity Controlled Compression Ignition ◽  
Hcci Combustion ◽  
Heavy Duty Diesel Engine ◽  
Heavy Duty Diesel

The present study uses numerical simulations to explore the use of hydrated (wet) ethanol for reactivity controlled compression ignition (RCCI) operation in a heavy duty diesel engine. RCCI uses in-cylinder blending of a low reactivity fuel with a high reactivity fuel and has demonstrated significant fuel efficiency and emissions benefits using a variety of fuels, including gasoline and diesel. Combustion timing is controlled by the local blended fuel reactivity (i.e., octane number), and the combustion duration can be controlled by establishing optimized gradients in fuel reactivity in the combustion chamber. In the present study, the low reactivity fuel was hydrated ethanol while the higher reactivity fuel was diesel. First, the effect of water on ethanol/water/diesel mixtures in completely premixed HCCI combustion was investigated using GT-Power and single-zone CHEMKIN simulations. The results showed that the main impact of the water in the ethanol is to reduce the initial in-cylinder temperature due to vaporization cooling. Next, multi-dimensional engine modeling was performed using the KIVA code at engine loads from 5 to 17 bars IMEP at 1300 rev/min with various grades of hydrated ethanol and a fixed diesel fraction of the total fuel. The results show that hydrated ethanol can be used in RCCI combustion with gross indicated thermal efficiencies up to 55% and very low emissions. A 70/30 ethanol/water mixture (by mass) was found to yield the best results across the entire load range without the need for EGR.

Investigation of the Effect of Injection and Control Strategies on Combustion Instability in Reactivity-Controlled Compression Ignition Engines

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
David T. Klos ◽  
Sage L. Kokjohn
Keyword(s):  
Direct Injection ◽  
Combustion Instability ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Cfd Modeling ◽  
Surface Model ◽  
Injection Timing ◽  
Compression Ignition ◽  
Reactivity Controlled Compression Ignition

This paper uses detailed computational fluid dynamics (CFD) modeling with the kiva-chemkin code to investigate the influence of injection timing, combustion phasing, and operating conditions on combustion instability. Using detailed CFD simulations, a large design of experiments (DOE) is performed with small perturbations in the intake and fueling conditions. A response surface model (RSM) is then fit to the DOE results to predict cycle-to-cycle combustion instability. Injection timing had significant tradeoffs between engine efficiency, emissions, and combustion instability. Near top dead center (TDC) injection timing can significantly reduce combustion instability, but the emissions and efficiency drop close to conventional diesel combustion levels. The fuel split between the two direct injection (DI) injections has very little effect on combustion instability. Increasing exhaust gas recirculation (EGR) rate, while making adjustments to maintain combustion phasing, can significantly reduce peak pressure rise rate (PPRR) variation until the engine is on the verge of misfiring. Combustion phasing has a very large impact on combustion instability. More advanced phasing is much more stable, but produces high PPRRs, higher NOx levels, and can be less efficient due to increased heat transfer losses. The results of this study identify operating parameters that can significantly improve the combustion stability of dual-fuel reactivity-controlled compression ignition (RCCI) engines.

scholarly journals Isolating the effects of reactivity stratification in reactivity-controlled compression ignition with iso-octane and n-heptane on a light-duty multi-cylinder engine

2017 ◽  
Vol 19 (9) ◽  
pp. 907-926 ◽  
Author(s):  
Martin L Wissink ◽  
Scott J Curran ◽  
Greg Roberts ◽  
Mark PB Musculus ◽  
Christine Mounaïm-Rousselle
Keyword(s):  
High Efficiency ◽  
Direct Injection ◽  
Combustion Process ◽  
High Reactivity ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Reactivity Controlled Compression Ignition ◽  
Fundamental Understanding ◽  
Primary Reference ◽  
Primary Reference Fuels

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.

Reactivity Controlled Compression Ignition (RCCI) Using Premixed Hydrated Ethanol and Direct Injection Diesel

2011 ◽  
Author(s):  
A. B. Dempsey ◽  
B. Das Adhikary ◽  
S. Viswanathan ◽  
R. D. Reitz
Keyword(s):  
Direct Injection ◽  
Fuel Efficiency ◽  
High Reactivity ◽  
Net Energy ◽  
Water Mixture ◽  
Compression Ignition ◽  
Load Range ◽  
Pure Ethanol ◽  
Reactivity Controlled Compression Ignition ◽  
Heavy Duty Diesel

Previous research has shown that a Homogeneous Charge Compression Ignition (HCCI) engine with efficient heat recovery can operate on a 35 to 65% volumetric mixture of ethanol-in-water while achieving high brake thermal efficiency (∼39%) and very low NOx emissions [4]. The major advantage of utilizing hydrated ethanol as a fuel is that the net energy gain improves from 21 to 55% of the heating value of ethanol and its co-products, since significant energy must be expended to remove water during production. This is required because wet ethanol is not suitable for conventional combustion engines. For example, spark ignition engines demand the use of pure ethanol because the dilution caused by water reduces the flame speed, resulting in misfire and problems due to condensation. The present study uses numerical simulations to explore the use of wet ethanol for Reactivity Controlled Compression Ignition (RCCI) operation in a heavy duty diesel engine. RCCI uses in-cylinder blending of a low reactivity fuel with a high reactivity fuel and has demonstrated significant fuel efficiency and emissions benefits using a variety of fuels, including gasoline and diesel. Combustion timing is controlled by the local blended fuel reactivity (i.e. octane number), and the combustion duration can be controlled by establishing optimized gradients in fuel reactivity in the combustion chamber. In the present study, the low reactivity fuel was hydrated ethanol while the higher reactivity fuel was diesel. First, the effect of water on ethanol/water/diesel HCCI was investigated using GT-Power and single-zone CHEMKIN simulations. The results showed that the main impact of the water in the ethanol is to reduce the IVC temperature due to vaporization cooling. Next, multidimensional engine modeling was performed using the KIVA code at engine loads from 5 to 17 bar IMEP at 1300 rev/min with various grades of hydrated ethanol and a fixed diesel fraction of the total fuel. The results show that hydrated ethanol can be used in a RCCI engine with gross indicated thermal efficiencies up to 55% and very low emissions. A 70/30 ethanol/water mixture (by mass) was found to yield the best results across the entire load range without the need for EGR.

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