SI/HCCI Mode Switching Optimization in a Gasoline Direct Injection Engine Employing Dual Univalve System

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Yintong Liu ◽  
Liguang Li ◽  
Haifeng Lu ◽  
Stephan Schmitt ◽  
Jun Deng ◽  
...  
Keyword(s):  
High Efficiency ◽  
Direct Injection ◽  
Load Condition ◽  
Gasoline Direct Injection ◽  
Mode Switching ◽  
Nox Emissions ◽  
Combustion Mode ◽  
Timing Control ◽  
Main Challenge ◽  
Low Load

Homogeneous charge compression ignition (HCCI) is a feasible combustion mode meeting future stringent emissions regulations, and has high efficiency and low NOX and particle emissions. As the narrow working condition range is the main challenge limiting the industrialization of HCCI, combustion mode switching between SI and HCCI is necessary when employing HCCI in mass production engines. Based on a modified production gasoline direct injection (GDI) engine equipped with dual UniValve system (a fully continuously variable valvetrain system), SI/HCCI mode switching under low load condition is investigated. According to the results, combustion mode switching from SI to HCCI is more complicated than from HCCI to SI. As HCCI requires strict boundary conditions for reliable and repeatable fuel auto-ignition, abnormal combustion easily appears in transition cycle, especially when combustion switches from SI to HCCI. Timing control strategies can optimize the combustion of transition cycles. With the optimization of timing control, the mode switching from SI to HCCI can be completed with only two transition cycles of late combustion, and abnormal combustion can be avoided during the mode switching from HCCI to SI. Under the low load condition, the indicated efficiency reaches 39% and specific NOX emissions drop down to around 1 mg/L/s when the combustion mode is switched to HCCI mode. Compared to SI mode, the indicated efficiency is increased by 10% and the specific NOX emissions are reduced by around 85%.

Investigation of Injection Strategies to Improve High Efficiency RCCI Combustion With Diesel and Gasoline Direct Injection

2012 ◽  
Author(s):  
Martin L. Wissink ◽  
Jae H. Lim ◽  
Derek A. Splitter ◽  
Reed M. Hanson ◽  
Rolf D. Reitz
Keyword(s):  
High Efficiency ◽  
Direct Injection ◽  
High Reactivity ◽  
Gasoline Direct Injection ◽  
Cylinder Wall ◽  
Nox Emissions ◽  
Heavy Duty ◽  
Fuel Vaporization ◽  
Heavy Duty Diesel ◽  
Injection Strategies

Experiments were performed to investigate injection strategies for improving engine-out emissions of RCCI combustion in a heavy-duty diesel engine. Previous studies of RCCI combustion using port-injected low-reactivity fuel (e.g., gasoline or iso-octane) and direct-injected high-reactivity fuel (e.g., diesel or n-heptane) have reported greater than 56% gross indicated thermal efficiency while meeting the EPA 2010 heavy-duty PM and NOx emissions regulations in-cylinder. However, CO and UHC emissions were higher than in diesel combustion. This increase is thought to be caused by crevice flows of trapped low-reactivity fuel and lower cylinder wall temperatures. In the present study, both the low- and high-reactivity fuels were direct-injected, enabling more precise targeting of the low-reactivity fuel as well as independent stratification of equivalence ratio and reactivity. Experiments with direct-injection of both gasoline and diesel were conducted at 9 bar IMEP and compared to results from experiments with port-injected gasoline and direct-injected diesel at matched conditions. The results indicate that reductions in UHC, CO, and PM are possible with direct-injected gasoline, while maintaining similar gross indicated efficiency as well as NOx emissions well below the EPA 2010 heavy-duty limit. Additionally, experimental results were simulated using multi-dimensional modeling in the KIVA-3V code coupled to a Discrete Multi-Component fuel vaporization model. The simulations suggest that further UHC reductions can be made by using wider injector angles which direct the gasoline spray away from the crevices.

Comparison between gasoline direct injection and compressed natural gas port fuel injection under maximum load condition

Energy ◽  
2020 ◽  
Vol 197 ◽  
pp. 117173 ◽  
Author(s):  
Jeongwoo Lee ◽  
Cheolwoong Park ◽  
Jongwon Bae ◽  
Yongrae Kim ◽  
Sunyoup Lee ◽  
...  
Keyword(s):  
Natural Gas ◽  
Fuel Injection ◽  
Direct Injection ◽  
Load Condition ◽  
Maximum Load ◽  
Gasoline Direct Injection ◽  
Compressed Natural Gas ◽  
Port Fuel Injection

Investigation of Cold Starting and Combustion Mode Switching as Methods to Improve Low Load RCCI Operation

2015 ◽  
Author(s):  
Reed Hanson ◽  
Rolf Reitz
Keyword(s):  
Steady State ◽  
High Speed ◽  
Closed Loop ◽  
Cold Start ◽  
Mode Switching ◽  
Combustion Mode ◽  
Low Load ◽  
Performance And Emissions ◽  
And Performance ◽  
Emissions And Performance

Reactivity Controlled Compression Ignition (RCCI) is an engine combustion strategy that utilizes in-cylinder fuel blending to produce low NOx and PM emissions while maintaining high thermal efficiency. The current study investigates RCCI and conventional diesel combustion (CDC) operation in a light-duty multi-cylinder engine using a transient capable engine test cell. The main focus of the work uses engine experiments to investigate methods which can improve low-load RCCI operation. The first set of experiments investigated RCCI operation during cold start conditions. The next set of tests investigated combustion mode switching between RCCI and CDC. During the cold start tests, RCCI performance and emissions were measured over a range of engine coolant temperatures from 48 to 85°C. A combination of open and closed loop controls enabled RCCI to operate at a 1,500 rpm, 1 bar BMEP operating point over this range of coolant temperatures. At a similar operating condition, i.e. 1,500 rpm, 2 bar BMEP, the engine was instantaneously switched between CDC and RCCI combustion using the same open and closed loop controls as the cold start testing. During the mode switch tests, emissions and performance were measured with high speed sampling equipment. The tests revealed that it was possible to operate RCCI down to 48°C with simple open and closed loop controls with emissions and efficiency similar to the warm steady-state values. Next, the mode switching tests were successful in switching combustion modes with minimal deviations in emissions and performance in either mode at steady-state.

Simulations of Multi-Mode Combustion Regimes Realizable in a Gasoline Direct Injection Engine

2020 ◽  
Author(s):  
Sayop Kim ◽  
Riccardo Scarcelli ◽  
Yunchao Wu ◽  
Johannes Rohwer ◽  
Ashish Shah ◽  
...  
Keyword(s):  
Mixed Mode ◽  
Direct Injection ◽  
Flow Property ◽  
Gasoline Direct Injection ◽  
Combustion Model ◽  
Compression Ignition ◽  
Fuel Blend ◽  
Combustion Dynamics ◽  
Low Load ◽  
Multi Mode

Abstract Lean and dilute gasoline compression ignition (GCI) operation in spark ignition (SI) engines are an attractive strategy to attain high fuel efficiency and low NOx levels. However, this combustion mode is often limited to low-load engine conditions due to the challenges associated with autoignition controllability. In order to overcome this constrain, multi-mode (MM) operating strategies, consisting of advanced compression ignition (ACI) at low load and conventional SI at high load, have been proposed. In this 3-D CFD study the concept of multi-mode combustion using two RON98 gasoline fuel blends (Co-Optima Alkylate and E30) in a gasoline direct injection (GDI) engine were explored. To this end, a new reduced mechanism for simulating the kinetics of E30 fuel blend is introduced in this study. To cover the varying engine load demands for multi-mode engines, primary combustion dynamics observed in ACI and SI combustion modes was characterized and validated against experimental measurements. In order to implement part-load conditions, a strategy of mode-transition between SI and ACI combustion (i.e., mixed-mode combustion) was then explored numerically by creating a virtual test condition. The results obtained from the mixed-mode simulations highlight an important feature that deflagrative flame propagation regime coexists with ignition-assisted end-gas autoignition. This study also identifies a role of turbulent flow property adjacent to premixed flame front in characterizing the mixed-mode combustion. The employed hybrid combustion model was verified to perform simulations aiming at suitable range of multi-mode engine operations.

scholarly journals Investigation on Blending Effects of Gasoline Fuel with N-Butanol, DMF, and Ethanol on the Fuel Consumption and Harmful Emissions in a GDI Vehicle

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1845 ◽  
Author(s):  
Haifeng Liu ◽  
Xichang Wang ◽  
Diping Zhang ◽  
Fang Dong ◽  
Xinlu Liu ◽  
...  
Keyword(s):  
Steady State ◽  
Fuel Consumption ◽  
Large Fraction ◽  
Direct Injection ◽  
Transient State ◽  
Gasoline Direct Injection ◽  
Nox Emissions ◽  
Fuel Blends ◽  
Wide Range ◽  
Oxygenated Fuel

The effects of three kinds of oxygenated fuel blends—i.e., ethanol-gasoline, n-butanol-gasoline, and 2,5-dimethylfuran (DMF)-gasoline-on fuel consumption, emissions, and acceleration performance were investigated in a passenger car with a chassis dynamometer. The engine mounted in the vehicle was a four-cylinder, four-stroke, turbocharging gasoline direct injection (GDI) engine with a displacement of 1.395 L. The test fuels include ethanol-gasoline, n-butanol-gasoline, and DMF-gasoline with four blending ratios of 20%, 50%, 75%, and 100%, and pure gasoline was also tested for comparison. The original contribution of this article is to systemically study the steady-state, transient-state, cold-start, and acceleration performance of the tested fuels under a wide range of blending ratios, especially at high blending ratios. It provides new insight and knowledge of the emission alleviation technique in terms of tailoring the biofuels in GDI turbocharged engines. The results of our works showed that operation with ethanol–gasoline, n-butanol–gasoline, and DMF–gasoline at high blending ratios could be realized in the GDI vehicle without any modification to its engine and the control system at the steady state. At steady-state operation, as compared with pure gasoline, the results indicated that blending n-butanol could reduce CO2, CO, total hydrocarbon (THC), and NOX emissions, which were also decreased by employing a higher blending ratio of n-butanol. However, a high fraction of n-butanol increased the volumetric fuel consumption, and so did the DMF–gasoline and ethanol–gasoline blends. A large fraction of DMF reduced THC emissions, but increased CO2 and NOX emissions. Blending n-butanol can improve the equivalent fuel consumption. Moreover, the particle number (PN) emissions were significantly decreased when using the high blending ratios of the three kinds of oxygenated fuels. According to the results of the New European Drive Cycle (NEDC) cycle, blending 20% of n-butanol with gasoline decreased CO2 emissions by 5.7% compared with pure gasoline and simultaneously reduced CO, THC, NOX emissions, while blending ethanol only reduced NOX emissions. PN and particulate matter (PM) emissions decreased significantly in all stages of the NEDC cycle with the oxygenated fuel blends; the highest reduction ratio in PN was 72.87% upon blending 20% ethanol at the NEDC cycle. The high proportion of n-butanol and DMF improved the acceleration performance of the vehicle.

Control of a spark ignition homogeneous charge compression ignition mode transition on a gasoline direct injection engine

2007 ◽  
Vol 221 (7) ◽  
pp. 867-875 ◽  
Author(s):  
G Tian ◽  
Z Wang ◽  
Q Ge ◽  
J Wang ◽  
S Shuai
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Direct Injection ◽  
Spark Ignition ◽  
Gasoline Direct Injection ◽  
Compression Ignition ◽  
Combustion Mode ◽  
Key Issues ◽  
Cam Profile ◽  
Negative Valve Overlap ◽  
Homogeneous Charge

The hybrid combustion mode is an ideal operation strategy for a gasoline homogeneous charge compression ignition (HCCI) engine. A stable and smooth spark ignition (SI)/HCCI switch has been an issue in the research on multimode combustion. In this paper, the switch process has two key issues; the cam profile and throttle opening. With the developed two-stage cam system, the valve phase strategy can be switched within one engine cycle, from the normal cam profile for the SI mode to a negative valve overlap (NVO) profile for the HCCI mode, or vice versa. For a smoother and more stable switch, the throttle change was separated from the cam profile switch, which was called the stepped switch. The effect of throttle opening on HCCI combustion was studied, and the results showed that the concept of the stepped switch was reliable. With gasoline direct injection (GDI) the combustion mode switches from both SI and HCCI sides were smooth, rapid, and robust, without any abnormal combustion such as knocking and misfiring.

scholarly journals Combustion stability control of gasoline compression ignition (GCI) under low-load conditions: A review

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Leilei Liu ◽  
Zhifa Zhang ◽  
Yue Liang ◽  
Fan Zhang ◽  
Binbin Yang
Keyword(s):  
High Efficiency ◽  
Stability Control ◽  
Combustion Stability ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Combustion Mode ◽  
Low Load ◽  
Temperature Combustion ◽  
Future Work ◽  
Load Conditions

Abstract With greater energy pressure and stricter emission standards, increasing power output and reducing emissions of engines are simultaneously required. To achieve this, considerable researches are motivated. In recent years, key and representative developments in the field of high-efficiency and clean engines have been carried out. Among them, a low temperature combustion concept called gasoline compression ignition (GCI) is widely considered by universities and research institutions around the world, since it has the potential to achieve ultra-low NO X and soot emissions while maintaining high thermal efficiency. However, GCI combustion mode has certain issues to be solved, such as combustion instability under low-load conditions. Therefore, this paper reviews the experimental, computational and optical studies on the combustion stability control of GCI combustion mode during low loads and describes the recent progress to improve combustion stability as well as points out the future work finally.

scholarly journals Effect of Injection Strategies in Diesel/NG Direct-Injection Engines on the Combustion Process and Emissions under Low-Load Operating Conditions

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 990 ◽  
Author(s):  
Jinze Li ◽  
Longfei Deng ◽  
Jianjun Guo ◽  
Min Zhang ◽  
Zhenyuan Zi ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Direct Injection ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Operating Conditions ◽  
Diffusion Combustion ◽  
Combustion Mode ◽  
Low Load ◽  
Hc Emissions ◽  
Injection Strategies

The direct injection of natural gas (NG), which is an important research direction in the development of NG engines, has the potential to improve thermal efficiency and emissions. When NG engines operate in low-load conditions, combustion efficiency decreases and hydrocarbon (HC) emissions increase due to lean fuel mixtures and slow flame propagation speeds. The effect of two combustion modes (partially premixed compression ignition (PPCI) and high pressure direct injection (HPDI)) on combustion processes was investigated by CFD (Computational Fluid Dynamics), with a focus on different injection strategies. In the PPCI combustion mode, NG was injected early in the compression stroke and premixed with air, and then the pilot diesel was injected to cause ignition near the top dead center. This combustion mode produced a faster heat release rate, but the HC emissions were higher, and the combustion efficiency was lower. In the HPDI combustion mode, the diesel was injected first and ignited, and then the NG was injected into the flame. This combustion mode resulted in higher emissions of NOx and soot, with a diffusion combustion in the cylinder. HC emissions significantly decreased. Compared with PPCI combustion, HPDI had a higher thermal efficiency.

Simulations of Multi-Mode Combustion Regimes Realizable in a Gasoline Direct Injection Engine

2021 ◽  
pp. 1-26
Author(s):  
Sayop Kim ◽  
Riccardo Scarcelli ◽  
Yunchao Wu ◽  
Johannes Rohwer ◽  
Ashish Shah ◽  
...  
Keyword(s):  
Mixed Mode ◽  
Direct Injection ◽  
Flow Property ◽  
Gasoline Direct Injection ◽  
Combustion Model ◽  
Compression Ignition ◽  
Fuel Blend ◽  
Combustion Dynamics ◽  
Low Load ◽  
Multi Mode

Abstract Lean and dilute gasoline compression ignition (GCI) operation in spark ignition (SI) engines are an attractive strategy to attain high fuel efficiency and low NOx levels. However, this combustion mode is often limited to low-load engine conditions due to challenges associated with autoignition controllability. In order to overcome this constrain, multi-mode (MM) operating strategies, consisting of advanced compression ignition (ACI) at low load and conventional SI at high load, have been proposed. In this 3-D CFD study the concept of multi-mode combustion using two RON98 gasoline fuel blends (Co-Optima Alkylate and E30) in a gasoline direct injection (GDI) engine were explored. To this end, a new reduced mechanism for simulating the kinetics of E30 fuel blend is introduced in this study. To cover the varying engine load demands for multi-mode engines, primary combustion dynamics observed in ACI and SI combustion modes was characterized and validated against experimental measurements. In order to implement part-load conditions, a strategy of mode-transition between SI and ACI combustion (i.e., mixed-mode combustion) was then explored numerically by creating a virtual test condition. The results obtained from the mixed-mode simulations highlight an important feature that deflagrative flame propagation regime coexists with ignition-assisted end-gas autoignition. This study also identifies a role of turbulent flow property adjacent to premixed flame front in characterizing the mixed-mode combustion. The employed hybrid combustion model was verified to perform simulations aiming at suitable range of multi-mode engine operations.

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