Potential of reactivity-controlled compression ignition with reverse reactivity stratification (R-RCCI) fueled with gasoline and polyoxymethylene dimethyl ethers (PODEn)

2021 ◽  
pp. 146808742110136
Author(s):  
Huiquan Duan ◽  
Ming Jia ◽  
Jinpeng Bai ◽  
Yaopeng Li
Keyword(s):  
Thermal Efficiency ◽  
Volume Fraction ◽  
Pressure Rise ◽  
Combustion Efficiency ◽  
High Reactivity ◽  
Combustion Stability ◽  
Compression Ignition ◽  
Reactivity Controlled Compression Ignition ◽  
Trade Off ◽  
Polyoxymethylene Dimethyl Ethers

To improve the trade-off between thermal efficiency and peak heat release rate (HRR) of partially premixed combustion (PPC) and the combustion efficiency of reactivity-controlled compression ignition (RCCI), the combustion mode with premixed high-reactivity fuel and direct-injection (DI) low-reactivity fuel, called RCCI with reverse reactivity stratification (R-RCCI), was explored at low loads in a light-duty diesel engine in this study. Compared with diesel, polyoxymethylene dimethyl ethers (PODEn) has better volatility, which is beneficial for the formation of premixed charge, so it was used as the premixed high-reactivity fuel for R-RCCI in this work. The gasoline and P20G80 (PODEn/gasoline blends with the volume fraction of 20%/80%) were respectively applied as the DI low-reactivity fuel. By investigating the combustion characteristics of R-RCCI, it is found that R-RCCI can break the trade-off between combustion efficiency and nitrogen oxides (NOx) emissions. This is because the combustion efficiency of R-RCCI is dominated by the spray location of the DI fuel rather than the 50% burn point (CA50). As the start of injection (SOI) timing is retarded, the fuel injected within the piston bowl increases, and combustion efficiency, as well as indicated thermal efficiency (ITE), is considerably promoted. Meanwhile, CA50 progressively retards with delayed SOI timing, which effectively reduces NOx emissions. The soot emissions of R-RCCI are also extremely low. The maximum ITE of PODEn/P20G80 R-RCCI is significantly higher than that of PODEn/gasoline R-RCCI. This occurs because the higher reactivity of P20G80 can reduce the sensitivity of CA50 to SOI timing and improve combustion stability, so a more delayed SOI timing is allowed to improve ITE. With the same engine configurations, R-RCCI can reduce peak pressure rise rate and improve combustion stability, while enhancing combustion efficiency and ITE compared with RCCI at the low-load conditions tested in this study.

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.

Engine performance and emission characteristics of a compression ignition engine fuelled with diesel/dimethoxymethane blends

2005 ◽  
Vol 219 (7) ◽  
pp. 905-914 ◽  
Author(s):  
Y Ren ◽  
Z H Huang ◽  
D M Jiang ◽  
L X Liu ◽  
K Zeng ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Mass Fraction ◽  
Volume Fraction ◽  
Engine Performance ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Performance And Emission ◽  
Fuel Blends ◽  
Performance And Emissions ◽  
Combustion Phase

The performance and emissions of a compression ignition engine fuelled with diesel/dimethoxymethane (DMM) blends were studied. The results showed that the engine's thermal efficiency increased and the diesel equivalent brake specific fuel consumption (b.s.f.c.) decreased as the oxygen mass fraction (or DMM mass fraction) of the diesel/DMM blends increased. This change in the diesel/DMM blends was caused by an increased fraction of the premixed combustion phase, an oxygen enrichment, and an improvement in the diffusive combustion phase. A remarkable reduction in the exhaust CO and smoke can be achieved when operating on the diesel/DMM blend. Flat NO x/smoke and thermal efficiency/smoke curves are presented when operating on the diesel/DMM fuel blends, and a simultaneous reduction in both NO x and smoke can be realized at large DMM addition. Thermal efficiency and NO x give the highest value at 2 per cent oxygen mass fraction (or 5 per cent DMM volume fraction) for the combustion of diesel/DMM blends.

scholarly journals Impact of injection strategies on combustion characteristics, efficiency and emissions of gasoline compression ignition operation in a heavy-duty multi-cylinder engine

2018 ◽  
Vol 21 (8) ◽  
pp. 1426-1440 ◽  
Author(s):  
Buyu Wang ◽  
Michael Pamminger ◽  
Ryan Vojtech ◽  
Thomas Wallner
Keyword(s):  
High Temperature ◽  
Thermal Efficiency ◽  
Fuel Injection ◽  
Pressure Rise ◽  
Pilot Injection ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Temperature Combustion ◽  
Gas Recirculation ◽  
Direct Fuel Injection

Gasoline compression ignition using a single gasoline-type fuel for direct/port injection has been shown as a method to achieve low-temperature combustion with low engine-out NOx and soot emissions and high indicated thermal efficiency. However, key technical barriers to achieving low-temperature combustion on multi-cylinder engines include the air handling system (limited amount of exhaust gas recirculation) as well as mechanical engine limitations (e.g. peak pressure rise rate). In light of these limitations, high-temperature combustion with reduced amounts of exhaust gas recirculation appears more practical. Furthermore, for high-temperature gasoline compression ignition, an effective aftertreatment system allows high thermal efficiency with low tailpipe-out emissions. In this work, experimental testing was conducted on a 12.4 L multi-cylinder heavy-duty diesel engine operating with high-temperature gasoline compression ignition combustion with port and direct injection. Engine testing was conducted at an engine speed of 1038 r/min and brake mean effective pressure of 1.4 MPa for three injection strategies, late pilot injection, early pilot injection, and port/direct fuel injection. The impact on engine performance and emissions with respect to varying the combustion phasing were quantified within this study. At the same combustion phasing, early pilot injection and port/direct fuel injection had an earlier start of combustion and higher maximum pressure rise rates than late pilot injection attributable to more premixed fuel from pilot or port injection; however, brake thermal efficiencies were higher with late pilot injection due to reduced heat transfer. Early pilot injection also exhibited the highest cylinder-to-cylinder variations due to differences in injector behavior as well as the spray/wall interactions affecting mixing and evaporation process. Overall, peak brake thermal efficiency of 46.1% and 46% for late pilot injection and port/direct fuel injection was achieved comparable to diesel baseline (45.9%), while early pilot injection showed the lowest brake thermal efficiency (45.3%).

INITIAL RESULTS ON A NEW LIGHT-DUTY 2.7L OPPOSED-PISTON GASOLINE COMPRESSION IGNITION MULTI-CYLINDER ENGINE

2022 ◽  
pp. 1-8
Author(s):  
Ashwin Salvi ◽  
Reed Hanson ◽  
Rodrigo Zermeno ◽  
Gerhard Regner ◽  
Mark Sellnau ◽  
...  
Keyword(s):  
Pressure Rise ◽  
Cost Effective ◽  
Combustion Noise ◽  
Combustion Stability ◽  
Residual Fraction ◽  
Compression Ignition ◽  
Light Duty ◽  
Peak Cylinder Pressure ◽  
Near Term ◽  
Initial Results

Abstract Gasoline compression ignition (GCI) is a cost-effective approach to achieving diesel-like efficiencies with low emissions. The fundamental architecture of the two-stroke Achates Power Opposed-Piston Engine (OP Engine) enables GCI by decoupling piston motion from cylinder scavenging, allowing for flexible and independent control of cylinder residual fraction and temperature leading to improved low load combustion. In addition, the high peak cylinder pressure and noise challenges at high-load operation are mitigated by the lower BMEP operation and faster heat release for the same pressure rise rate of the OP Engine. These advantages further solidify the performance benefits of the OP Engine and emonstrate the near-term feasibility of advanced combustion technologies, enabled by the opposed-piston architecture. This paper presents initial results from a steady state testing on a brand new 2.7L OP GCI multi-cylinder engine designed for light-duty truck applications. Successful GCI operation calls for high compression ratio, leading to higher combustion stability at low-loads, higher efficiencies, and lower cycle HC+NOX emissions. Initial results show a cycle average brake thermal efficiency of 31.7%, which is already greater than 11% conventional engines, after only ten weeks of testing. Emissions results suggest that Tier 3 Bin 160 levels can be achieved using a traditional diesel after-treatment system. Combustion noise was well controlled at or below the USCAR limits. In addition, initial results on catalyst light-off mode with GCI are also presented.

Experimental Comparison of GCI and Diesel Combustion in a Medium-Duty Opposed-Piston Engine

2018 ◽  
Author(s):  
Reed Hanson ◽  
Ashwin Salvi ◽  
Fabien Redon ◽  
Gerhard Regner
Keyword(s):  
Thermal Efficiency ◽  
Combustion Efficiency ◽  
Experimental Comparison ◽  
Diesel Combustion ◽  
Compression Ignition ◽  
Piston Engine ◽  
Load Range ◽  
Combustion Performance ◽  
Poppet Valve

The Achates Power Inc. (API) Opposed Piston (OP) Engine architecture provides fundamental advantages that increase thermal efficiency over current poppet valve 4 stroke engines. In this paper, combustion performance of diesel and gasoline compression ignition (GCI) combustion in a medium duty, OP engine are shown. By using GCI, NOx and/or soot reductions can be seen compared to diesel combustion at similar or increased thermal efficiencies. The results also show that high combustion efficiency can be achieved with GCI combustion with acceptable noise and stability over the same load range as diesel combustion in an OP engine.

Initial Results on a New Light-Duty 2.7L Opposed-Piston Gasoline Compression Ignition Multi-Cylinder Engine

2018 ◽  
Author(s):  
Ashwin Salvi ◽  
Reed Hanson ◽  
Rodrigo Zermeno ◽  
Gerhard Regner ◽  
Mark Sellnau ◽  
...  
Keyword(s):  
Pressure Rise ◽  
High Load ◽  
Combustion Stability ◽  
Residual Fraction ◽  
Compression Ignition ◽  
Cylinder Pressure ◽  
Peak Cylinder Pressure ◽  
Low Load ◽  
Initial Results ◽  
Load Conditions

Gasoline compression ignition (GCI) is a cost-effective approach to achieving diesel-like efficiencies with low emissions. Traditional challenges with GCI arise at low-load conditions due to low charge temperatures causing combustion instability and at high-load conditions due to peak cylinder pressure and noise limitations. The fundamental architecture of the two-stroke Achates Power Opposed-Piston Engine (OP Engine) enables GCI by decoupling piston motion from cylinder scavenging, allowing for flexible and independent control of cylinder residual fraction and temperature leading to improved low load combustion. In addition, the high peak cylinder pressure and noise challenges at high-load operation are mitigated by the lower BMEP operation and faster heat release for the same pressure rise rate of the OP Engine. These advantages further solidify the performance benefits of the OP Engine and demonstrate the near-term feasibility of advanced combustion technologies, enabled by the opposed-piston architecture. This paper presents initial results from a steady state testing on a brand new 2.7L OP GCI multi-cylinder engine. A part of the recipe for successful GCI operation calls for high compression ratio, leading to higher combustion stability at low-loads, higher efficiencies, and lower cycle HC+NOx emissions. In addition, initial results on catalyst light-off mode with GCI are also presented. The OP Engine’s architectural advantages enable faster and earlier catalyst light-off while producing low emissions, which further improves cycle emissions and fuel consumption over conventional engines.

Optimization of piston bowl and valve system in compression ignition engine fueled with gasoline/diesel/polyoxymethylene dimethyl ethers for high efficiency

2019 ◽  
pp. 146808741986538
Author(s):  
Bowen Li ◽  
Haoye Liu ◽  
Linjun Yu ◽  
Zhi Wang ◽  
Jianxin Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Efficiency ◽  
High Efficiency ◽  
Compression Ignition ◽  
Combustion Mode ◽  
Compression Ignition Engine ◽  
Valve System ◽  
Percentage Points ◽  
Polyoxymethylene Dimethyl Ethers ◽  
Variable Valve

Polyoxymethylene dimethyl ethers, with excellent volatility and oxygen content of up to 49%, have great potential to improve engine performance and emission characteristics. In this study, experiments were carried out in a single-cylinder engine fueled with gasoline/diesel/polyoxymethylene dimethyl ethers blend fuel using multiple premixed compression ignition combustion mode along with engine optimization to exploit the high-efficiency potential. The thermal efficiency was increased by 9.4 percentage points after transforming the combustion mode from conventional diesel mode to gasoline/diesel/polyoxymethylene dimethyl ethers multiple premixed compression ignition mode. A fully variable valve system and a redesigned low-heat-transfer piston were used to further improve the thermal efficiency. The low-heat-transfer piston had a 15% lower area–volume ratio compared with the original ω-type piston. By replacing the original ω-type piston with the low-heat-transfer piston, the heat transfer loss was reduced by 2.29 percentage points and thus indicated thermal efficiency could be increased by 2.37 percentage points, which was up to 50.03%. On the basis of the low-heat-transfer piston, indicated thermal efficiency could be further increased to 51.09% with the application of fully variable valve system due to the longer ignition delay and more premixed combustion. At the same time, NOX emissions could be controlled below 0.4 g/kW·h using high exhaust gas recirculation ratio, which equaled the NOX emission limit of Euro VI standard. Although soot emissions could be increased due to weak turbulence and insufficient intake charge using the low-heat-transfer piston and fully variable valve system, it was still lower than those of the original diesel engines.

An Experimental Investigation of Reactivity-Controlled Compression Ignition Combustion in a Single-Cylinder Diesel Engine Using Hydrous Ethanol

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Wei Fang ◽  
Junhua Fang ◽  
David B. Kittelson ◽  
William F. Northrop
Keyword(s):  
Experimental Investigation ◽  
Diesel Engine ◽  
Thermal Efficiency ◽  
Alternative Fuels ◽  
Compression Ignition ◽  
Reactivity Controlled Compression Ignition ◽  
Single Cylinder ◽  
Diesel Injection ◽  
Soot Emissions ◽  
Hydrous Ethanol

Dual-fuel reactivity-controlled compression ignition (RCCI) combustion using port injection of a less reactive fuel and early-cycle direct injection (DI) of a more reactive fuel has been shown to yield both high thermal efficiency and low NOX and soot emissions over a wide engine operating range. Conventional and alternative fuels such as gasoline, natural gas, and E85 as the lower reactivity fuel in RCCI have been studied by many researchers; however, published experimental investigations of hydrous ethanol use in RCCI are scarce. Making greater use of hydrous ethanol in internal combustion engines has the potential to dramatically improve the economics and life cycle carbon dioxide emissions of using bioethanol. In this work, an experimental investigation was conducted using 150 proof hydrous ethanol as the low reactivity fuel and commercially available diesel as the high reactivity fuel in an RCCI combustion mode at various load conditions. A modified single-cylinder diesel engine was used for the experiments. Based on previous studies on RCCI combustion by other researchers, early-cycle split-injection strategy of diesel fuel was used to create an in-cylinder fuel reactivity distribution to maintain high thermal efficiency and low NOX and soot emissions. At each load condition, timing and mass fraction of the first diesel injection was held constant, while timing of the second diesel injection was swept over a range where stable combustion could be maintained. Since hydrous ethanol is highly resistant to auto-ignition and has large heat of vaporization, intake air heating was needed to obtain stable operations of the engine. The study shows that 150 proof hydrous ethanol can be used as the low reactivity fuel in RCCI through 8.6 bar indicated mean effective pressure (IMEP) and with ethanol energy fraction up to 75% while achieving simultaneously low levels of NOX and soot emissions. With increasing engine load, less intake heating is needed and exhaust gas recirculation (EGR) is required to maintain low NOX emissions.

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