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

2014 ◽  
Author(s):  
David T. Klos ◽  
Sage L. Kokjohn
Keyword(s):  
Control Strategies ◽  
Combustion Instability ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Cfd Modeling ◽  
Surface Model ◽  
Injection Timing ◽  
Reactivity Controlled Compression Ignition ◽  
And Control

This paper uses detailed CFD modeling with the KIVA-CHEMKIN code to investigate the influence of injection timing, combustion phasing and operating conditions on combustion instability. Using detailed computational fluid dynamics (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 TDC injection timing can significantly reduce combustion instability, but the emissions and efficiency drop to close to conventional diesel combustion (CDC) levels. The fuel split between the two DI injections has very little effect on combustion instability. Increasing EGR rate, while making adjustments to maintain combustion phasing, can significantly reduce 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 peak pressure rise rates, 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 RCCI engines.

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.

Parametric Study of Ignition and Combustion Characteristics From a Gasoline Compression Ignition Engine Using Two Different Reactivity Fuels

2016 ◽  
Author(s):  
Khanh Cung ◽  
Toby Rockstroh ◽  
Stephen Ciatti ◽  
William Cannella ◽  
S. Scott Goldsborough
Keyword(s):  
High Speed ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Injection Timing ◽  
Strong Impact ◽  
Boost Pressure ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Ignition And Combustion

Unlike homogeneous charge compression ignition (HCCI) that has the complexity in controlling the start of combustion event, partially premixed combustion (PPC) provides the flexibility of defining the ignition timing and combustion phasing with respect to the time of injection. In PPC, the stratification of the charge can be influenced by a variety of methods such as number of injections (single or multiple injections), injection pressure, injection timing (early to near TDC injection), intake boost pressure, or combination of several factors. The current study investigates the effect of these factors when testing two gasoline-like fuels of different reactivity (defined by Research Octane Number or RON) in a 1.9-L inline 4-cylinder diesel engine. From the collection of engine data, a full factorial analysis was created in order to identify the factors that most influence the outcomes such as the location of ignition, combustion phasing, combustion stability, and emissions. Furthermore, the interaction effect of combinations of two factors or more was discussed with the implication of fuel reactivity under current operating conditions. The analysis was done at both low (1000 RPM) and high speed (2000 RPM). It was found that the boost pressure and air/fuel ratio have strong impact on ignition and combustion phasing. Finally, injection-timing sweeps were conducted whereby the ignition (CA10) of the two fuels with significantly different reactivity were matched by controlling the boost pressure while maintaining a constant lambda (air/fuel equivalence ratio).

Effects of EGR and Boost Pressure on Reactivity Controlled Compression Ignition (RCCI) Engine at High Load Operating Conditions

2014 ◽  
Author(s):  
Yifeng Wu ◽  
Rolf D. Reitz
Keyword(s):  
Peak Pressure ◽  
Pressure Rise ◽  
High Load ◽  
Operating Conditions ◽  
Boost Pressure ◽  
Compression Ignition ◽  
Effective Pressure ◽  
Reactivity Controlled Compression Ignition ◽  
Brake Mean Effective Pressure ◽  
Diesel Injection

Reactivity Controlled Compression Ignition (RCCI) at engine high load operating conditions is investigated in this study. The effects of EGR and boost pressure on RCCI combustion were studied by using a multi-dimensional computational fluid dynamics (CFD) code. The model was first compared with a previous CFD model, which has been validated against steady-state experimental data of gasoline-diesel RCCI in a multi-cylinder light duty engine. An RCCI piston with a compression ratio of 15:1 was then proposed to improve the combustion and emissions at high load. The simulation results showed that 18 bar indicated mean effective pressure (IMEP) could be achieved with gasoline-diesel RCCI at an EGR rate of 35 % and equivalence ratio of 0.96, while the peak pressure rise rate (PPRR) and engine combustion efficiency could both be controlled at reasonable levels. Simulations using both early and late direct-injection (DI) of diesel fuel showed that RCCI combustion at high load is very sensitive to variations of the exhaust gas recirculation (EGR) amount. Higher IMEP is obtained by using early diesel injection, and it is less sensitive to EGR variation compared to late diesel injection. Reduced unburned hydrocarbon (HC), carbon monoxide (CO), soot and slightly more nitrogen oxides (NOx) emissions were seen for early diesel injection. HC, CO and soot emissions were found to be more sensitive to EGR variation at late diesel injection timings. However, there was little difference in terms of peak pressure, efficiencies, PPRR and phasing under varying EGR rates. The effect of boost pressure on RCCI at high load operating conditions was also studied at different EGR rates. It was found that combustion and emissions were improved, and the sensitivity of the combustion and emission to EGR was reduced with higher boost pressures. In addition, cases with similar combustion phasing and reasonable PPRR were analyzed by using an experimentally validated GT-Power model. The results indicated that although higher IMEP was generated at higher boost pressures, the brake mean effective pressure (BMEP) was similar compared to that obtained with lower boost pressures due to higher pumping losses.

An Approach for Investigating Adaptive Control Strategies to Improve Combustion Stability Under Dilute Operating Conditions

2005 ◽  
Author(s):  
K. Dean Edwards ◽  
Robert M. Wagner ◽  
Timothy J. Theiss ◽  
C. Stuart Daw
Keyword(s):  
Adaptive Control ◽  
Emission Reduction ◽  
Internal Combustion Engines ◽  
Control Strategies ◽  
Fuel Efficiency ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Combustion Model ◽  
Combustion Instabilities ◽  
The Impact

Dilute operation of internal combustion engines through lean fueling and/or high levels of exhaust gas recirculation (EGR) is frequently employed to increase fuel efficiency, reduce NOx emissions, and promote enhanced combustion modes such as HCCI. The maximum level of dilution is limited by the development of combustion instabilities that produce unacceptable levels of cycle-to-cycle combustion variability. These combustion instabilities are frequently stimulated by the nonlinear feedback associated with the residual and recirculated exhaust gases exchanged between successive cycles. However, with the application of adaptive control, it is possible to limit the severity of the combustion variability and regain efficiency and emission reduction benefits that would otherwise be lost. In order to better characterize the benefits of adaptive control, we have employed a two-zone phenomenological combustion model to simulate the onset of combustion instabilities under dilute operating conditions and illustrate the impact of these instabilities on emissions and fuel efficiency. The two-zone in-cylinder combustion model is coupled to a WAVE engine-simulation code, allowing rapid simulation of several hundred successive engine cycles with many external engine parametric effects included. By applying adaptive feedback control to the WAVE model, we demonstrate how mitigation of the extreme combustion events can result in improved efficiency and reduced emissions levels. We expect that this approach can be used to estimate the potential benefits of implementing adaptive control strategies on specific engine platforms to achieve further efficiency and emission-reduction gains.

scholarly journals Experiments in Active Control of Stall on an Aeroengine Gas Turbine

1997 ◽  
Author(s):  
Christopher Freeman ◽  
Alexander G. Wilson ◽  
Ivor J. Day ◽  
Malcolm A. Swinbanks
Keyword(s):  
Control System ◽  
Control Strategies ◽  
Pressure Rise ◽  
Pressure Transducers ◽  
Operating Range ◽  
Stable Operating ◽  
Response Pressure ◽  
All Speeds ◽  
Stall Control ◽  
And Control

This paper describes work carried out between 1989 and 1994 to investigate the application of ‘Active Stall Control’ to a Rolls-Royce Viper turbojet. The results demonstrate that stall control is feasible and can increase the stable operating range by up to 25% of pressure rise. Stall disturbances were detected using rings of high response pressure transducers positioned at different axial planes along the compressor, and processed using a PC-based data acquisition and control system. Actuation was provided by six hydraulically operated sleeve valves positioned to recirculate air over all or part of the compressor. Stall was artificially induced using combinations of inbleed into the combustor outer casing, fuel spiking, hot gas ingestion and inlet pressure spoiling, thus replicating many of the transient conditions commonly observed to make a compressor prone to stall. Results are compared from a number of stall control strategies including those demonstrated at low speed by Paduano et al [1993] and Day [1993]. Best results were obtained with detection of non-axisymmetric disturbances coupled with axisymmetric control action. A control system of this type is demonstrated to be capable of extending the stable engine operating range at all speeds and with each method of inducing stall.

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

2014 ◽  
Vol 136 (9) ◽  
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.

Combustion Tuning Guidelines: Understanding and Mitigating Dynamic Instabilities in Modern Gas Turbine Combustors

2004 ◽  
Author(s):  
Leonard C. Angello ◽  
Carlo Castaldini
Keyword(s):  
Operating Conditions ◽  
Combustion Noise ◽  
Combustion Stability ◽  
Combustion Instabilities ◽  
Monitoring And Control ◽  
Single Digit ◽  
Active Monitoring ◽  
Critical System ◽  
Premature Failure ◽  
And Control

DLN combustors used in modern utility Combustion Turbines (CTs) must operate within tight tolerances of equivalence ratio, fuel/air mixing and turbulence in order to deliver single digit NOx emission performance, while maintaining combustion stability and design power output. As lean NOx emissions from large CTs are driven to increasingly lower levels, even small changes in combustion conditions or manufacturing tolerances can lead to the onset of combustion instabilities and acoustic combustion noise. If left unattended, dynamic oscillations in ultra-low NOx premix combustors can produce resonant acoustics that can in turn cause adverse impacts on performance, including the ability to deliver capacity, or the premature failure of critical system components and emergency shut-downs. For example, it is widely accepted that extreme changes in ambient temperature, or minor changes in fuel composition and temperature, or the use of power augmentation techniques under certain conditions, can lead to combustion instabilities. EPRI is leading a multi-task program to map the operating regime for stable combustion in modern DLN combustors; identify key operating conditions that most influence the onset of combustion instabilities; and develop DLN tuning guidelines based on users’ experience and vendors’ monitoring and control systems. The overall objective of these projects is to maximize the operational flexibility of modern CTs based on implementation of active monitoring and control guidelines aimed at anticipating, preventing, and effectively responding to the onset of combustion-induced dynamic instabilities and CT noise. This paper briefly discusses the dynamics of combustion instabilities in premix DLN combustors; presents the preliminary results from detailed parametric analysis of a large database; and our findings on DLN tuning approaches such as modulating fuel flows and changing inlet guide vanes, that can be used effectively to control combustion instabilities.

Impact of Diesel Engine Technology Advancement on Particulate Exhaust Emission - A Review

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
Awadhesh Kumar Tiwari ◽  
R.K. Mandloi
Keyword(s):  
Diesel Engine ◽  
Control Strategies ◽  
Combustion Process ◽  
Exhaust Emissions ◽  
Operating Conditions ◽  
Exhaust Emission ◽  
Particulate Emission ◽  
Technology Advancement ◽  
Emission Effect ◽  
And Control

In present scenario clean technologies with lesser fuel consumption for better air quality is needed from automobile sector. There is need to maintain regulatory emission standards, approaches to minimize green house gases. Therefore, it is highly required to address two major challenges, better engine efficiency with minimum exhaust emissions. Excessive work has been done on fuel improvement, combustion process and exhaust emission on diesel engine advancement since last 40 years. This review covers a comprehensive summary of the existing details related to technology advancement and its effect on pollution control. The investigations have focused on determination of the best operating conditions like overview of modified fuel, particulate emission effect and control strategies which include engine modifications and with advanced combustion strategies vehicular particulate exhaust emissions can be significantly controlled.

Influence of injection strategies on knock resistance and combustion characteristics in a DISI engine

2018 ◽  
Vol 233 (10) ◽  
pp. 2637-2649
Author(s):  
Haiqiao Wei ◽  
Jie Yu ◽  
Aifang Shao ◽  
Lei Zhou ◽  
Jianxiong Hua ◽  
...  
Keyword(s):  
Single Injection ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Combustion Stability ◽  
Injection Timing ◽  
Split Injection ◽  
Injection Strategy ◽  
Double Injection ◽  
The Impact ◽  
Injection Strategies

The combustion of a direct injection spark ignition engine is significantly affected by the fuel injection strategy due to the impact this strategy has on the gas-mixture formation and the turbulence flow. However, comprehensive assessments on both knock and engine performances for different injection strategies are generally lacking. Therefore, the main objective of the present study is to provide an experimental evidence of how a single injection strategy and a split injection strategy compare in terms of both knock tendency and engine performances like thermal efficiency, torque and combustion stability. Starting from the optimization of a single injection strategy, a split injection strategy is then evaluated. Under the present operating conditions, an optimum secondary injection timing of 100 CAD BTDC is found to have significant improvements on both the knock resistance and the overall engine performances. It should be noted that the present results indicate that the relationship between double injection and anti-knock performance is not monotonous. In addition, the double injection shows superior potential in improving fuel economy and power performance in contrast with the single injection thanks to a more stable combustion when a late injection timing is applied.

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