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Investigation Of Rcci Operation With Customized Pistons In A Light Duty Multi Cylinder Engine Using Dieseline
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Book Synopsis Investigation of RCCI Operation with Customized Pistons in a Light-duty Multi-cylinder Engine Using Dieseline by :
Download or read book Investigation of RCCI Operation with Customized Pistons in a Light-duty Multi-cylinder Engine Using Dieseline written by and published by . This book was released on 2016 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: In an attempt to increase efficiency and lower critical and highly regulated emissions (i.e., NOx, PM and CO2) many advanced combustion strategies have been investigated. Most of the current strategies fall into the category of low temperature combustion (LTC), which allow emissions mandates to be met in-cylinder along with anticipated reduction in cost and complexity. These strategies, such as homogeneous charge compression ignition (HCCI), premixed charge compression ignition (PCCI), partially premixed combustion (PPC) and reactivity controlled compression ignition (RCCI), use early injection timings, resulting in a highly lean charge with increased specific heat ratios to improve thermal efficiency and reduce PM emissions. Lower combustion temperatures also avoid the activation of NOx formation reactions. However, the lean air/fuel ratio decreases fuel oxidation rates of CO and HC and, due to longer ignition delays with high peak pressure rise rate (PPRR) and heat release rates (HRR), confines the engine’s operating loads and speeds. A strategy to reduce these negative effects of LTC is RCCI, which generally uses two fuels with different reactivities in order to optimize ignitability and equivalence ratio stratification. It has demonstrated improvements in efficiency and low NOx and PM emissions by utilizing in-cylinder fuel blending, while the simultaneous optimization of fuel reactivity results in increased engine operating space. The current work investigates Reactivity Controlled Compression Ignition (RCCI) combustion in a light-duty multi-cylinder engine over steady-state and transient operating conditions using also fast exhaust sampling emissions equipment for UHC, NO and PM measurements. A “single-fuel ” approach for RCCI combustion was studied using port-injected and direct-injected (DI) cetane improved gasoline with custom designed, 15.3:1 compression ratio, pistons. In addition, experiments were conducted using mixtures of gasoline and diesel, i.e., “dieseline”, as the high reactivity fuel. The experiments were performed over a broad selection of “ad hoc” load and speed points in order to examine performance and emission effects of a less reactive DI fuel mixture to in turn reduce the need for a second fuel. This work also helps to demonstrate the requirements for high levels of boost in a multi-cylinder engine during RCCI operation. Comparisons were also made to an HCCI/GCI like combustion strategy using similar gasoline/diesel fuel blends.
Book Synopsis Characterization of Reactivity Controlled Compression Ignition (RCCI) Using Premixed Gasoline and Direct-Injected Gasoline with a Cetane Improver on a Multi-Cylinder Engine by :
Download or read book Characterization of Reactivity Controlled Compression Ignition (RCCI) Using Premixed Gasoline and Direct-Injected Gasoline with a Cetane Improver on a Multi-Cylinder Engine written by and published by . This book was released on 2015 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of the present paper was to characterize Reactivity Controlled Compression Ignition (RCCI) using a single-fuel approach of gasoline and gasoline mixed with a commercially available cetane improver on a multi-cylinder engine. RCCI was achieved by port-injecting a certification grade 96 research octane gasoline and direct-injecting the same gasoline mixed with various levels of a cetane improver, 2-ethylhexyl nitrate (EHN). The EHN volume percentages investigated in the direct-injected fuel were 10, 5, and 2.5%. The combustion phasing controllability and emissions of the different fueling combinations were characterized at 2300 rpm and 4.2 bar brake mean effective pressure over a variety of parametric investigations including direct injection timing, premixed gasoline percentage, and intake temperature. Comparisons were made to gasoline/diesel RCCI operation on the same engine platform at nominally the same operating condition. The experiments were conducted on a modern four cylinder light-duty diesel engine that was modified with a port-fuel injection system while maintaining the stock direct injection fuel system. The pistons were modified for highly premixed operation and feature an open shallow bowl design. The results indicate that the authority to control the combustion phasing through the fuel delivery strategy (e.g., direct injection timing or premixed gasoline percentage) is not a strong function of the EHN concentration in the direct-injected fuel. It was also observed that NOx emissions are a strong function of the global EHN concentration in-cylinder and the combustion phasing. Finally, in general, NOx emissions are significantly elevated for gasoline/gasoline+EHN operation compared with gasoline/diesel RCCI operation at a given operating condition.
Book Synopsis High Power Output Operation of RCCI Combustion by :
Download or read book High Power Output Operation of RCCI Combustion written by and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A computational investigation of methods to extend the upper limit of power output of reactivity controlled compression ignition (RCCI) engines was performed. The study utilized two approaches. The first approach is to increase the engine speed while maintaining a medium load. The second approach is to operate at higher loads without changing the engine speed. Iso-octane and n-heptane were used to represent the low-reactivity fuel and high-reactivity fuel, respectively. A light-duty diesel engine was modeled for the high speed dual-fuel RCCI combustion study. With high-speed operation several benefits were identified. Firstly, the peak pressure rise rates (PPRR), both crank angle-based and time-based, were reduced compared to those with low-speed operation. Secondly, at high speed the NO formation residence time became short, leading to reduced NOx emissions. Lastly, a frictional penalty analysis of high-speed operation using the Chen-Flynn model was conducted, which showed only 0.5 bar FMEP increase compared to that at low-speed. These findings indicate that high-speed RCCI is a very promising path for high-power output operation. For the high-load operation study use of dual direct-injectors was explored in order to direct-inject both fuels. Analysis of the optimum injection strategy revealed two main physical mechanisms enabling high-load operation with dual direct-injectors. The first exploited local evaporative cooling from the iso-octane injection, which delayed the iso-octane ignition. The second mechanism was related to the shorter chemical residence time of the iso-octane due to its late delivery into the cylinder. It was also noted that n-heptane's role as an ignition source could not be achieved with just iso-octane. Finally, the co-axial injector location assumption was removed by using an actual dual-injector layout. Unlike results with the co-axial injector design, the actual dual-injector layout exhibited soot and CO emission problems. In order to attempt to accommodate off-center injector locations, various injector hole patterns were tested. Although these unconventional injector hole patterns improved the emissions, it is concluded that the development of a co-axial dual-fuel injector is imperative in order to achieve clean RCCI combustion at high load.
Book Synopsis Experimental Investigation of Dual-fuel RCCI Operation in a Light-duty Engine by : John R. Kaddatz
Download or read book Experimental Investigation of Dual-fuel RCCI Operation in a Light-duty Engine written by John R. Kaddatz and published by . This book was released on 2011 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental Investigation of Transient RCCI Combustion in a Light Duty Diesel Engine by :
Download or read book Experimental Investigation of Transient RCCI Combustion in a Light Duty Diesel Engine written by and published by . This book was released on 2013 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low Temperature Combustion (LTC) is currently being researched as a way to reduce problematic emissions (i.e., NOx and PM) from compression-ignition engines while maintaining high fuel efficiency. One of the primary types of LTC is Premixed Compression Ignition (PCI), with some examples of PCI being homogeneous charge compression ignition (HCCI), premixed charge compression ignition (PCCI), reactivity controlled compression ignition (RCCI) and partially premixed combustion (PPC). These LTC strategies use early fuel injections to allow sufficient time for air/fuel mixing before combustion. By increasing the amount of air/fuel premixing, NOx and PM emissions can be lowered due to the reduced local and global equivalence ratios. The lean nature of PCI also maintains high thermal efficiency due to the reduced heat transfer losses from the reduced peak combustion temperatures. However, too much air/fuel premixing can lead to rapid energy release rates, limiting the operation space for PCI. To combat this problem, the combustion strategy of interest for the study, RCCI, uses fuel reactivity gradients to increase combustion duration (i.e., reduce the energy release rate) and phasing control, thereby increasing the engine operating space for PCI operation. Previous tests [1-7] have shown promising results for petroleum-based fuels with RCCI. Recent work at Oak Ridge National Laboratory (ORNL) has shown how blends of biofuels with petroleum fuels can improve RCCI combustion performance [8,9] The work sets out to examine biofuel performance over a wide engine operating space both at steady-state and transient operating conditions with RCCI combustion. It is hoped to demonstrate the capability and effects of using bio-derived fuels in place of conventional petroleum-derived fuels for advanced combustion strategies under real-world operating conditions. In RCCI operation, blends of biodiesel and ethanol fuels will be investigated to examine the fuel effects on the combustion event.
Book Synopsis Dual-fuel Reactivity Controlled Compression Ignition (RCCI) with Alternative Fuels by :
Download or read book Dual-fuel Reactivity Controlled Compression Ignition (RCCI) with Alternative Fuels written by and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research will demonstrate that Reactivity Controlled Compression Ignition (RCCI) has several advantages over other LTC concepts in regards to fuel flexibility and combustion controllability. RCCI is a dual-fuel partially premixed combustion concept. In this strategy, a low reactivity fuel, such as gasoline or an alcohol fuel, is premixed via port fuel injection (PFI) and a high reactivity fuel, such as diesel fuel, is direct injected (DI) during the compression stroke. Once it was clear that dual-fuel RCCI operation had great potential in terms of combustion controllability, which is a great challenge for LTC strategies, the study focused on alternative fuels with RCCI combustion. The light-duty engine was used to study two different fuel combinations: gasoline/diesel and methanol/diesel. In addition to the fuels comparison, a modified piston bowl geometry was studied and compared to the stock re-entrant bowl. The modified piston featured a wide/shallow bowl with a matched geometric compression ratio to the stock piston of ~17.3. Using the modified piston, the gross indicated efficiency of RCCI combustion was significantly improved at light loads due to increases in combustion efficiency and decreases in heat transfer losses. At higher loads the modified piston also performed better than the stock piston, but the improvements were not as significant. The final portion of this research looks at the effects of cetane improvers on gasoline, ethanol, and methanol's fuel reactivity and the implications for RCCI combustion. In all three base fuels it was found that 2-ethylhexyl nitrate is more effective at increasing fuel reactivity (i.e., suppressing the octane number) compared to di-tert-butyl peroxide. However, 2-ethylhexyl nitrate has a potential disadvantage due its nitrate group, which can manifest itself as NOx emissions in the exhaust. The relationship between the fuel-bound nitrate group and the engine-out NOx emissions was extensively characterized. It was also observed that methanol's response to cetane improvers was better than that of ethanol, in spite of the fact that they have similar reactivities in their neat form.
Book Synopsis Optimization of the Air Handling System of a Multi-cylinder Light Duty Engine Running on Reactivity Controlled Compression Ignition - by :
Download or read book Optimization of the Air Handling System of a Multi-cylinder Light Duty Engine Running on Reactivity Controlled Compression Ignition - written by and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low Temperature Combustion (LTC) Strategies such as Reactivity Controlled Compression Ignition (RCCI) are highly sensitive to intake conditions, which are influenced by the gas exchange process. Because the gas exchange process is dependent on air handling system characteristics, optimizing the air handling system for improved RCCI engine performance is necessary. Major objectives were: 1. Improve combustion efficiency while mitigating unburnt hydrocarbon (UHC) and carbon monoxide (CO) emissions at low load, 2. Determine system parameters and configurations for high loads and 3. Examine variable valve actuation (VVA) and manifold redesign to maximize fuel efficiency. Zero-dimensional, one-dimensional and multi-dimensional models were used in this simulation study. Early Exhaust Valve Opening (EEVO) using fully flexible variable valvetrains and cam-phasers, and cylinder deactivation were evaluated for their impact on aftertreatment efficiency and fuel economy at low load. For near-idle conditions, cylinder deactivation in which only one cylinder was fired gave the best fuel economy and catalyst efficiency. For the second objective of performing high load system simulation, a low pressure (LP) EGR circuit was incorporated into the engine model. High Pressure EGR could not be used for high loads as the pre-turbine pressure was insufficient to drive EGR flow. Moreover, insufficient exhaust energy would be available to the turbine, resulting in lower boost pressures. For the final objective, the stock exhaust manifold was redesigned using the Divided Exhaust Period (DEP) concept by splitting it into two manifolds, one connected to each exhaust valve. By using VVA to separately actuate the valves, overlap between the valves was varied, changing the exhaust distribution between the two manifolds, and thereby regulating boost pressure. With DEP, due to lower overall backpressures, pumping penalty decreased, but the pumping benefit was negated by parasitic losses from the supercharger which had to compensate for the boost deficit. Replacing the fixed geometry turbocharger with a variable geometry turbocharger (VGT) improved the Brake Specific Fuel Consumption (BSFC) over the base engine by 1%, while bypassing the turbine at low load gave elevated exhaust gas temperatures for thermal management.
Book Synopsis DESIGN OF REAL-TIME COMBUSTION FEEDBACK SYSTEM AND EXPERIMENTAL STUDY OF AN RCCI ENGINE FOR CONTROL by :
Download or read book DESIGN OF REAL-TIME COMBUSTION FEEDBACK SYSTEM AND EXPERIMENTAL STUDY OF AN RCCI ENGINE FOR CONTROL written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Premixed compression ignition (PCI) technologies offer high efficiency and low emissions but are usually confined by limited operation range as well as high pressure rise and heat release rate. In this work, a more recently developed PCI mode is explored where in-cylinder blending of two fuels with different auto-ignition characteristics (diesel and gasoline) is utilized to create reactivity stratification such that heat release rate and combustion timing can be controlled. This mode has been defined as Reactivity Controlled Compression Ignition (RCCI). As part of this thesis, the main aim is to study various parameters that can be used to control combustion phasing. Also, steady state mapping of the engine is done so as to explore the operating range for the current engine setup. Best efficiencies as well as highest loads are obtained for higher Premixed Ratio (PR) values and advanced Start of Injection (SOI) timings, where as lower PR fuel blends are needed to achieve low load limit. The analysis is also extended to transient RCCI operation for observing various dynamics involved and their effects on combustion phasing. As part of realizing full-load range operation, switching to conventional Spark-Ignition (SI) combustion mode is also carried out. Various dynamics involved in the switching process are captured. A cycle-by-cycle closed loop combustion controller is designed and implemented on the engine to achieve optimum combustion phasing during transient engine operation. To provide feedback of combustion parameters like engine load and combustion phasing to the closed loop controller, a real-time combustion feedback system is designed and implemented utilizing Field Programmable Gate Array (FPGA).
Book Synopsis High Efficiency RCCI Combustion by :
Download or read book High Efficiency RCCI Combustion written by and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation of the pragmatic limits of Reactivity Controlled Compression Ignition (RCCI) engine efficiency was performed. The study utilized engine experiments combined with zero-dimensional modeling. Initially, simulations were used to suggest conditions of high engine efficiency with RCCI. Preliminary simulations suggested that high efficiency could be obtained by using a very dilute charge with a high compression ratio. Moreover, the preliminary simulations further suggested that with simultaneous 50% reductions in heat transfer and incomplete combustion, 60% gross thermal efficiency may be achievable with RCCI. Following the initial simulations, experiments to investigate the combustion process, fuel effects, and methods to reduce heat transfer and incomplete combustion reduction were conducted. The results demonstrated that the engine cycle and combustion process are linked, and if high efficiency is to be had, then the combustion event must be tailored to the initial cycle conditions. It was found that reductions to engine heat transfer are a key enabler to increasing engine efficiency. In addition, it was found that the piston oil jet gallery cooling in RCCI may be unnecessary, as it had a negative impact on efficiency. Without piston oil gallery cooling, it was found that RCCI was nearly adiabatic, achieving 95% of the theoretical maximum cycle efficiency (air standard Otto cycle efficiency).
Book Synopsis Experimental Investigation of Reactivity Controlled Compression Ignition (RCCI) Combustion in a Two-stroke Cycle Engine by : Scott R. Miles
Download or read book Experimental Investigation of Reactivity Controlled Compression Ignition (RCCI) Combustion in a Two-stroke Cycle Engine written by Scott R. Miles and published by . This book was released on 2014 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Aftertreatment Modeling of RCCI Engine During Transient Operation by : Nitya Kalva
Download or read book Aftertreatment Modeling of RCCI Engine During Transient Operation written by Nitya Kalva and published by . This book was released on 2014 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Addressing the Challenges of Advanced Compression Ignition Strategies Using Optimization Techniques with Machine Learning by : Naga Krishna Chaitanya Kavuri
Download or read book Addressing the Challenges of Advanced Compression Ignition Strategies Using Optimization Techniques with Machine Learning written by Naga Krishna Chaitanya Kavuri and published by . This book was released on 2018 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced compression ignition strategies like reactivity controlled compression ignition (RCCI) and gasoline compression ignition (GCI) have received substantial interest over the past few years. This is due to their potential to achieve reduced emissions, and higher efficiency, relative to conventional diesel combustion. However, most of the benefits seen in past research from these strategies were demonstrated under mid-load conditions. For these strategies to be implemented practically, similar benefits must be demonstrated across the drive cycle. Two particularly challenging areas of operation are high-load-low-speed and low-load-high-speed. Very limited research has been done with advanced compression ignition strategies in these points of the engine operating map. The reason for this is, at these operating conditions, there exists a mismatch between engine and chemistry time scales. The time scale mismatch results in either increased pressure rise rates or high levels of incomplete combustion, both of which make it difficult to operate. The work presented in this dissertation attempts to fill in these research gaps by using a combination of computational fluid dynamics modeling and genetic algorithm optimization. Initially, targeting high-load-low-speed conditions, a computational optimization study was performed at 20 bar indicated mean effective pressure and 1300 rev/min. with RCCI and GCI combustion strategies. The study was performed on a low compression ratio (12:1) piston with a "bathtub" geometry, since it was found to be well suited for high-load operation in earlier studies. The optima from the two combustion strategies were compared in terms of combustion characteristics, combustion control, and sensitivity to operating parameter variations. The results showed that both the strategies have similar combustion characteristics, including a two-stage heat release. A near top dead center injection initiated the combustion and its injection timing could be used to control the combustion phasing for both the strategies. Both the strategies required elevated levels of exhaust gas recirculation (EGR) (~55%) at a near stoichiometric global equivalence ratio to control the peak pressure rise rate. This resulted in high sensitivity to variations in EGR. To address this issue, high-load strategies at reduced EGR levels were investigated. A constraint analysis was performed using the optimization data to identify the constraints preventing operation at lower EGR levels. Results showed that operation at lower EGR rates was constrained by NOx emissions. Relaxing the NOx constraint enabled lower EGR operation with significant efficiency improvement. Allowing NOx emissions to increase to acceptable levels for selective catalytic reduction after treatment yielded an optimum at a moderate (~45%) level of EGR and a globally lean equivalence ratio of 0.8. This optimum case had near zero soot emissions and a higher net fluid efficiency (which accounted for the pumping loop work and the diesel exhaust fluid mass required to reduce the NOx emissions) compared to the earlier high EGR optima. Furthermore, the optimum case with NOx aftertreatment was compared with the high EGR optima in terms of combustion control and stability to operating condition fluctuations. The optimum with NOx aftertreatment retained the excellent combustion control seen with the high EGR optima, while reducing the sensitivity to operating parameter variations. The improved stability was attributed to operation at a reduced global equivalence ratio (from 0.93 to 0.8), which decreased the sensitivity to fluctuations in EGR rate. After addressing the issues at the high-load-low-speed operating condition, a low-load-high-speed operating point of 2 bar and 1800 rev/min. was simulated on the same engine used for the high-load studies. The results showed poor thermal efficiency for the low-load point. The poor efficiency was found to be due to an elevated level of incomplete combustion, which was a result of the low compression ratio piston used for the study. This result suggested that an optimum compression ratio should be identified considering the performance at the low-load and high-load conditions simultaneously. In addition, past optimization studies performed at low-load conditions have shown that the optimum bowl and injector design are very different compared to the high-load conditions. Accordingly, an optimization study was performed, considering performance at low- and high-load simultaneously. The optimum from the study was a stepped bowl geometry, with a compression ratio of 13.1:1, which resulted in a gross indicated efficiency of ~46% at both the loads. The study showed that the optimum design obtained from prioritizing one load deteriorates the performance at the other load. The results highlight the importance of considering multiple modes of the drive cycle simultaneously, when optimizing the engine design for advanced combustion strategies. It was shown that multiple modes of the drive cycle should be considered in optimization studies for advanced combustion strategies; however, the optimization with just two operating points took three months to complete. To consider all the modes of a drive cycle in the optimization, the computational time must be reduced. To address this issue, machine learning through Gaussian process regression was coupled with a genetic algorithm optimization to speed up the optimization process. Including machine learning within the optimization process reduced the computational time of optimization by 62%. The optimization process was further improved by using the Gaussian process regression model to check for the sensitivity of the designs to operating parameter variations during the optimization. The approach was tested with existing optimization data and it was shown that adding the stability check resulted in a reliable and stable optimum solution.
Book Synopsis EXPERIMENTAL STUDY, MODELLING AND CONTROLLER DESIGN FOR AN RCCI ENGINE by :
Download or read book EXPERIMENTAL STUDY, MODELLING AND CONTROLLER DESIGN FOR AN RCCI ENGINE written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Low Temperature Combustion (LTC) has got widespread attention over the past two decades in the field of Automotive Research and Development due to it's potential for achieving higher efficiencies with near-zero engine out NOx and soot emissions. Among all the LTC strategies Reactivity controlled compression ignition (RCCI) has shown the most promising results due to it's precise control over combustion phasing and heat release rate. However, RCCI being a dual-fuel stratified combustion, precise control over the injection timing of direct injected fuel and in-cylinder fuel reactivity of the mixture needs to be controlled effectively in order to achieve gross indicated thermal efficiencies as high as around 60%. This thesis focuses on developing real-time, model-based controller for controlling combustion phasing of an RCCI Engine. Optimum combustion phasing can be achieved by varying mixture reactivity and injection timing of higher reactive fuel. An experimental study was performed to study the effects of these variables on combustion phasing. Next,a mean-value and dynamic control-oriented model (COM) was developed to predict combustion phasing during steady-state and transient operating conditions. The validation results have shown that the COM was able to capture the experimental trends with minimal error. Next, for implementing in real time, a PI controller was developed using the COM to track the desired combustion phasing by adjusting duel-fuel premixed ratio and start of injection timing. The PI controller is then implemented on the engine plant. The validation results proved that the designed controller can follow the desired combustion phasing with an average error of 2 crank angle degrees and rise time of 3 engine cycles.
Book Synopsis Modeling and Control of Maximum Pressure Rise Rate in RCCI Engines by :
Download or read book Modeling and Control of Maximum Pressure Rise Rate in RCCI Engines written by and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Low Temperature Combustion (LTC) is a combustion strategy that burns fuel at lower temperatures and leaner mixtures in order to achieve high efficiency and near zero NOx emissions. Since the combustion happens at lower temperatures it inhibits the formation of NOx and soot emissions. One such strategy is Reactivity Controlled Compression Ignition (RCCI). One characteristic of RCCI combustion and LTC com- bustion in general is short burn durations which leads to high Pressure Rise Rates (PRR). This limits the operation of these engines to lower loads as at high loads, the Maximum Pressure Rise Rate (MPRR) hinders the use of this combustion strategy. This thesis focuses on the development of a model based controller that can control the Crank Angle for 50% mass fraction burn (CA50) and Indicated Mean Effective Pressure (IMEP) of an RCCI engine while limiting the MPRR to a pre determined limit. A Control Oriented Model (COM) is developed to predict the MPRR in an RCCI engine. This COM is then validated against experimental data. A statistical analysis of the experimental data is conducted to understand the accuracy of the COM. The results show that the COM is able to predict the MPRR with reasonable accuracy in steady state and transient conditions. Also, the COM is able to capture the trends during transient operation. This COM is then included in an existing cycle by cycle dynamic RCCI engine model and used to develop a Linear Parameter Varying (LPV) representation of an RCCI engine using Data Driven Modeling (DDM) approach with Support Vector Machines (SVM). This LPV representation is then used along with a Model Predictive Controller (MPC) to control the CA50 and IMEP of the RCCI engine model while limiting the MPRR. The controller was able to track the desired CA50 and IMEP with a mean error of 0.9 CAD and 4.7 KPa respectively while maintaining the MPRR below 5.8 bar/CAD.
Book Synopsis Numerical Study of a Reactivity Controlled Compression Ignition (RCCI) Engine Using Iso-octane and N-heptane by : Saif-al-din Mohd Abdullah
Download or read book Numerical Study of a Reactivity Controlled Compression Ignition (RCCI) Engine Using Iso-octane and N-heptane written by Saif-al-din Mohd Abdullah and published by . This book was released on 2018 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis MODEL-BASED CONTROL OF AN RCCI ENGINE by :
Download or read book MODEL-BASED CONTROL OF AN RCCI ENGINE written by and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Reactivity controlled compression ignition (RCCI) is a combustion strategy that offers high fuel conversion efficiency and near zero emissions of NOx and soot which can help in improving fuel economy in mobile and stationary internal combustion engine (ICE) applications and at the same time lower engine-out emissions. One of the main challenges associated with RCCI combustion is the difficulty in simultaneously controlling combustion phasing, engine load, and cyclic variability during transient engine operations. This thesis focuses on developing model based controllers for cycle-to-cycle combustion phasing and load control during transient operations. A control oriented model (COM) is developed by using mean value models to predict start of combustion (SOC) and crank angle of 50% mass fraction burn (CA50). The COM is validated using transient data from an experimental RCCI engine. The validation results show that the COM is able to capture the experimental trends in CA50 and indicated mean effective pressure (IMEP). The COM is then used to develop a linear quadratic integral (LQI) controller and model predictive controllers (MPC). Premixed ratio (PR) and start of injection (SOI) are the control variables used to control CA50, while the total fuel quantity (FQ) is the engine variable used to control load. The selection between PR and SOI is done using a sensitivity based algorithm. Experimental validation results for reference tracking using LQI and MPC show that the desired CA50 and IMEP can be attained in a single cycle during step-up and step-down transients and yield an average error of less than 1.6 crank angle degrees (CAD) in the CA50 and less than 35 kPa in the IMEP. This thesis presents the first study in the literature to design and implement LQI and MPC combustion controllers for RCCI engines.
Book Synopsis Reactivity Controlled Compression Ignition (RCCI) of Gasoline- CNG Mixtures by : Firmansyah Rashid (Abdul)
Download or read book Reactivity Controlled Compression Ignition (RCCI) of Gasoline- CNG Mixtures written by Firmansyah Rashid (Abdul) and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Reactivity controlled compression ignition (RCCI) is a dual fuel combustion method that relies on the significant difference in reactivity of the fuels involved. RCCI had a low performance at high engine speed due to its high tendency on knocking and high pressure rise rate. Therefore, this study investigates the effect of the fuel stratification on the RCCI combustion and its extended to the interaction of two low reactive fuels, gasoline and compressed natural gas (CNG), in the RCCI combustion system. The investigation was experimentally performed on a single cylinder engine and constant volume chamber. The stratification was created by varying injection timing in the engine by injecting CNG at 80° and 120° before top dead center (BTDC) and varying injection gap in the constant volume chamber with the gaps between two fuel injection timing were varied between 0 ms to 20 manuscript The results in the engine experiment show that proportions of gasoline and CNG and degree of stratification of CNG were found to be effective means of combustion control within certain limits of engine load and HC and CO emissions could be significantly reduced. While in constant volume chamber it has a significant effect on the combustion phasing. Stratified mixture produces shorter combustion duration while homogeneous mixture produces longer duration.
