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Combustion Emissions And Performance Optimization In A Di Pfi Rcci Diesel Natural Gas Turbocharged Engine
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Book Synopsis COMBUSTION, EMISSIONS, AND PERFORMANCE OPTIMIZATION IN A DI/PFI-RCCI DIESEL/NATURAL GAS TURBOCHARGED ENGINE by :
Download or read book COMBUSTION, EMISSIONS, AND PERFORMANCE OPTIMIZATION IN A DI/PFI-RCCI DIESEL/NATURAL GAS TURBOCHARGED 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 : Diesel-NG fuel blends are increasingly being used in Reactivity Controlled Compression Ignition (RCCI) applications due to high Brake Thermal Efficiency (BTE), low NOx and PM emissions. But it also has a few disadvantages such as high HC and CO emission and relatively low Exhaust Gas Temperature (EGT). This leads to find out the optimum tradeoff between emissions to meet the regulation and also investigate the cost of operation and find out the minimum liquid consumption (fuel + urea) in RCCI mode. A Cost Function (CF) including Brake Specific Fuel Consumption (BSFC) and Brake Specific Urea Consumption (BSUC) is considered and minimized in this study. This optimization helped to investigate the optimum input parameters between 3 to 12 bar IMEP at 1500 RPM engine speed. This study has been done while all the population in optimization process meet the Tier 3 Bin 20 emission regulations. To increase the number of data points in this optimization, a mathematical (numerical) model is developed to predict (or assess) the Diesel-NG RCCI data. Single fuel diesel only mode is also considered in this optimization, since high BTE of RCCI is limited to medium and high load operating conditions and due to the high HC and low EGT, RCCI may not be an ideal combustion mode at low loads. Parametric models have been developed and validated using experimental data on a light duty 1.9L inline 4 cylinder Compression Ignition (CI) engine as a function of independent input variables including, first and second Start of Injection (SOI1 and SOI2), Manifold Absolute Pressure (MAP), lambda, Exhaust Gas Recirculation (EGR) and Blending Ratio (BR), and validated using RCCI experimental data. In these models, selected emissions - including HC, CO, PM and NOx-, Exhaust Gas Temperature (EGT) and BSFC were computed using correlations as functions of independent input variables. The computed EGT were then used to estimate the Selective Catalyst Reduction (SCR) and Diesel Oxidation Catalyst (DOC) efficiencies to assess the emission data for different input variables by considering after-treatment system to see if they meet the tailpipe emission regulation. Running the engine with this calibrated input parameters not only meet the Tier 3 Bin 20 EPA standard, but also minimized the cost of operation in RCCI mode within 3 to 12 bar IMEP engine load at 1500 RPM engine speed.
Book Synopsis EXPERIMENTAL AND COMPUTATIONAL INVESTIGATION OF DUAL FUEL DIESEL- NATURAL GAS RCCI COMBUSTION IN A HEAVY-DUTY DIESEL ENGINE by :
Download or read book EXPERIMENTAL AND COMPUTATIONAL INVESTIGATION OF DUAL FUEL DIESEL- NATURAL GAS RCCI COMBUSTION IN A HEAVY-DUTY DIESEL ENGINE written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Among the various alternative fuels, natural gas is considered as a leading candidate for heavy-duty applications due to its availability and applicability in conventional internal combustion diesel engines. Compared to their diesel counterparts natural gas fueled spark-ignited engines have a lower power density, reduced low-end torque capability, limited altitude performance, and ammonia emissions downstream of the three-way catalyst. The dual fuel diesel/natural gas engine does not suffer with the performance limitations of the spark-ignited concept due to the flexibility of switching between different fueling modes. Considerable research has already been conducted to understand the combustion behavior of dual fuel diesel/natural gas engines. As reported by most researchers, the major difficulty with dual fuel operation is the challenge of providing high levels of natural gas substitution, especially at low and medium loads. In this study extensive experimental and simulation studies were conducted to understand the combustion behavior of a heavy-duty diesel engine when operated with compressed natural gas (CNG) in a dual fuel regime. In one of the experimental studies, conducted on a 13 liter heavy-duty six cylinder diesel engine with a compression ratio of 16.7:1, it was found that at part loads high levels of CNG substitution could be achieved along with very low NOx and PM emissions by applying reactivity controlled compression ignition (RCCI) combustion. When compared to the diesel-only baseline, a 75% reduction in both NOx and PM emissions was observed at a 5 bar BMEP load point along with comparable fuel consumption values. Further experimental studies conducted on the 13 liter heavy-duty six cylinder diesel engine have shown that RCCI combustion targeting low NOx emissions becomes progressively difficult to control as the load is increased at a given speed or the speed is reduced at a given load. To overcome these challenges a number of simulation studies were conducted to quantify the in-cylinder conditions that are needed at high loads and low to medium engine speeds to effectively control low NOx RCCI combustion. A number of design parameters were analyzed in this study including exhaust gas recirculation (EGR) rate, CNG substitution, injection strategy, fuel injection pressure, fuel spray angle and compression ratio. The study revealed that lowering the compression ratio was very effective in controlling low NOx RCCI combustion. By lowering the base compression ratio by 4 points, to 12.7:1, a low NOx RCCI combustion was achieved at both 12 bar and 20 bar BMEP load points. The NOx emissions were reduced by 75% at 12 bar BMEP while fuel consumption was improved by 5.5%. For the 20 BMEP case, a 2% improvement in fuel consumption was achieved with an 87.5% reduction in NOx emissions. At both load points low PM emissions were observed with RCCI combustion. A low NOx RCCI combustion system has multiple advantages over other combustion approaches, these include; significantly lower NOx and PM emission which allows a reduction in aftertreatment cost and packaging requirements along with application of higher CNG substitution rates resulting in reduced CO2 emissions.
Book Synopsis Advances in Compression Ignition Natural Gas – Diesel Dual Fuel Engines by : Hongsheng Guo
Download or read book Advances in Compression Ignition Natural Gas – Diesel Dual Fuel Engines written by Hongsheng Guo and published by Frontiers Media SA. This book was released on 2021-03-23 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Natural Gas Engines by : Kalyan Kumar Srinivasan
Download or read book Natural Gas Engines written by Kalyan Kumar Srinivasan and published by Springer. This book was released on 2018-11-03 with total page 419 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the various advanced reciprocating combustion engine technologies that utilize natural gas and alternative fuels for transportation and power generation applications. It is divided into three major sections consisting of both fundamental and applied technologies to identify (but not limited to) clean, high-efficiency opportunities with natural gas fueling that have been developed through experimental protocols, numerical and high-performance computational simulations, and zero-dimensional, multizone combustion simulations. Particular emphasis is placed on statutes to monitor fine particulate emissions from tailpipe of engines operating on natural gas and alternative fuels.
Book Synopsis Optimization Methods for the Mixture Formation and Combustion Process in Diesel Engines by : Jost Weber
Download or read book Optimization Methods for the Mixture Formation and Combustion Process in Diesel Engines written by Jost Weber and published by Cuvillier Verlag. This book was released on 2008 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Pathway to Higher Efficiency Internal Combustion Engines Through Thermochemical Recovery and Fuel Reforming by : Flavio Dal Forno Chuahy
Download or read book A Pathway to Higher Efficiency Internal Combustion Engines Through Thermochemical Recovery and Fuel Reforming written by Flavio Dal Forno Chuahy and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dual fuel reactivity controlled compression ignition (RCCI) combustion is a promising method to achieve high efficiency with near zero NOx and soot emissions; however, the requirement to carry two fuels on-board has limited practical applications. Advancements in catalytic reforming have demonstrated the ability to generate syngas (a mixture of CO and hydrogen) from a single hydrocarbon stream. The reformed fuel mixture can then be used as a low reactivity fuel stream to enable RCCI out of a single parent fuel. Beyond enabling dual-fuel combustion strategies out of a single parent fuel, fuel reforming can be endothermic and allow recovery of exhaust heat to drive the reforming reactions, potentially improving overall efficiency of the system. Previous works have focused on using reformed fuel to extend the lean limit of spark ignited engines, and enhancing the control of HCCI type combustion. The strategy pairs naturally with advanced dual-fuel combustion strategies, and the use of dual-fuel strategies in the context of on-board reforming and energy recovery has not been explored. Accordingly, the work presented in this dissertation attempts to fill in the gaps in the current literature and provide a pathway to "single" fuel RCCI combustion through a combination of experiments and computational fluid dynamics modeling. Initially, a system level analysis focusing on three common reforming techniques (i.e., partial oxidation, steam reforming and auto-thermal reforming) was conducted to evaluate the potential of reformed fuel. A system layout was proposed for each reforming technique and a detailed thermodynamic analysis using first- and second-law approaches were used to identify the sources of efficiency improvements. The results showed that reformed fuel combustion with a near TDC injection of diesel fuel can increase engine-only efficiency by 4% absolute when compared to a conventional diesel baseline. The efficiency improvements were a result of reduced heat transfer and shorter, more thermodynamically efficient, combustion process. For exothermic reforming processes, losses in the reformer outweigh the improvements to engine efficiency, while for endothermic processes the recovery of exhaust energy was able to allow the system efficiency to retain a large portion of the benefits to the engine combustion. Energy flow analysis showed that the reformer temperature and availability of high grade exhaust heat were the main limiting factors preventing higher efficiencies. RCCI combustion was explored experimentally for its potential to expand on the optimization results and achieve low soot and NOx emissions. The results showed that reformed fuel can be used with diesel to enable RCCI combustion and resulted in low NOx and soot emissions while achieving efficiencies similar to conventional diesel combustion. Experiments showed that the ratio H2/(H2+CO) is an important parameter for optimal engine operation. Under part-load conditions, fractions of H2/(H2+CO) higher than 60% led to pressure oscillations inside the cylinder that substantially increased heat transfer and negated any efficiency benefits. The system analysis approach was applied to the experimental results and showed that chemical equilibrium limited operation of the engine to sub-optimal operating conditions. RCCI combustion was able to achieve "diesel like" system level efficiencies without optimization of either the engine operating conditions or the combustion system. Reformed fuel RCCI was able to provide a pathway to meeting current and future emission targets with a reduction or complete elimination of aftertreatment costs. Particle size distribution experiments showed that addition of reformed fuel had a significant impact on the shape of the particle size distribution. Addition of reformed fuel reduced accumulation-mode particle concentration while increasing nucleation-mode particles. When considering the full range of particle sizes there was a significant increase in total particle concentration. However, when considering currently regulated (Dm>23nm) particles, total concentration was comparable. To address limitations identified in the system analysis of the RCCI experiments a solid oxide fuel cell was combined with the engine into a hybrid electrochemical combustion system. The addition of the fuel cell addresses the limitations by providing sufficient high grade heat to fully drive the reforming reactions. From a system level perspective, the impact of the high frequency oscillations observed in the experiments are reduced, as the system efficiency is less dependent on the engine efficiency. From an engine perspective, the high operating pressures and low reactivity of the anode gas allow reduction of the likelihood of such events. A 0-D system level code was developed and used to find representative conditions for experimental engine validation. The results showed that the system can achieve system electrical efficiencies higher than 70% at 1 MWe power level. Experimental validation showed that the engine was able to operate under both RCCI and HCCI combustion modes and resulted in low emissions and stable combustion. The potential of a hybrid electrochemical combustion system was demonstrated for high efficiency power generation
Book Synopsis Cost, Effectiveness, and Deployment of Fuel Economy Technologies for Light-Duty Vehicles by : National Research Council
Download or read book Cost, Effectiveness, and Deployment of Fuel Economy Technologies for Light-Duty Vehicles written by National Research Council and published by National Academies Press. This book was released on 2015-09-28 with total page 812 pages. Available in PDF, EPUB and Kindle. Book excerpt: The light-duty vehicle fleet is expected to undergo substantial technological changes over the next several decades. New powertrain designs, alternative fuels, advanced materials and significant changes to the vehicle body are being driven by increasingly stringent fuel economy and greenhouse gas emission standards. By the end of the next decade, cars and light-duty trucks will be more fuel efficient, weigh less, emit less air pollutants, have more safety features, and will be more expensive to purchase relative to current vehicles. Though the gasoline-powered spark ignition engine will continue to be the dominant powertrain configuration even through 2030, such vehicles will be equipped with advanced technologies, materials, electronics and controls, and aerodynamics. And by 2030, the deployment of alternative methods to propel and fuel vehicles and alternative modes of transportation, including autonomous vehicles, will be well underway. What are these new technologies - how will they work, and will some technologies be more effective than others? Written to inform The United States Department of Transportation's National Highway Traffic Safety Administration (NHTSA) and Environmental Protection Agency (EPA) Corporate Average Fuel Economy (CAFE) and greenhouse gas (GHG) emission standards, this new report from the National Research Council is a technical evaluation of costs, benefits, and implementation issues of fuel reduction technologies for next-generation light-duty vehicles. Cost, Effectiveness, and Deployment of Fuel Economy Technologies for Light-Duty Vehicles estimates the cost, potential efficiency improvements, and barriers to commercial deployment of technologies that might be employed from 2020 to 2030. This report describes these promising technologies and makes recommendations for their inclusion on the list of technologies applicable for the 2017-2025 CAFE standards.
Book Synopsis Diesel Combustion Optimization and Emissions Reduction Using Adaptive Injection Strategies (AIS) with Improved Numerical Models by : Yong Sun
Download or read book Diesel Combustion Optimization and Emissions Reduction Using Adaptive Injection Strategies (AIS) with Improved Numerical Models written by Yong Sun and published by . This book was released on 2007 with total page 234 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 0 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 Concepts in Turbocharging for Improved Efficiency and Emissions Reduction by : Mehrdad Zangeneh
Download or read book Concepts in Turbocharging for Improved Efficiency and Emissions Reduction written by Mehrdad Zangeneh and published by SAE International. This book was released on 2014-09-22 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: Legislative requirements to reduce CO2 emissions by 2020 have resulted in significant efforts by car manufacturers to explore various methods of pollution abatement. One of the most effective ways found so far is by shortening the cylinder stroke and downsizing the engine. This new engine then needs to be boosted, or turbocharged, to create the full and original load torque. Turbocharging has been and will continue to be a key component to the new technologies that will make a positive difference in the next-generation engines of years to come. Concepts in Turbocharging for Improved Efficiency and Emissions Reduction explores the many ways that turbocharging will deliver concrete results in meeting the new realities of sustainable, green transportation. This collection of very focused technical papers, selected by Mehrdad Zangeneh, PhD., a professor of thermo-fluids at University College in London, provides an assessment of several novel designs intended to improve fuel consumption and cap emissions, while maintaining torque at all speeds. The book is divided into four sections, each addressing the most cutting-edge technologies on the market today: o Two-Stage Turbocharging o Variable Geometry Compressors o Unconventional Compressor Configurations o Electrically Assisted Turbocharging
Book Synopsis Advances in Internal Combustion Engine Research by : Dhananjay Kumar Srivastava
Download or read book Advances in Internal Combustion Engine Research written by Dhananjay Kumar Srivastava and published by Springer. This book was released on 2017-11-29 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses all aspects of advanced engine technologies, and describes the role of alternative fuels and solution-based modeling studies in meeting the increasingly higher standards of the automotive industry. By promoting research into more efficient and environment-friendly combustion technologies, it helps enable researchers to develop higher-power engines with lower fuel consumption, emissions, and noise levels. Over the course of 12 chapters, it covers research in areas such as homogeneous charge compression ignition (HCCI) combustion and control strategies, the use of alternative fuels and additives in combination with new combustion technology and novel approaches to recover the pumping loss in the spark ignition engine. The book will serve as a valuable resource for academic researchers and professional automotive engineers alike.
Book Synopsis Performance Simulation and Control Design for Diesel Engine NOx Emission Reduction Technologies by : Hai Wu
Download or read book Performance Simulation and Control Design for Diesel Engine NOx Emission Reduction Technologies written by Hai Wu and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fuel efficiency and emission reductions are the two consistent drivers for internal combustion engine development for both on-highway and off-road vehicles. Advanced combustion technologies are proposed for the improvement of fuel consumption and reduction of harmful gas production inside the cylinder in laboratory engines. Outside cylinder technologies and after-treatment are the alternatives for a production engine to meet the stringent emission standards. Advanced control technologies play important roles in the realization of new technologies. This research was aimed at investigating possible techniques and feasible methods of implementation to reduce diesel engine emissions to meet the more stringent Tier 4 standards. In this study, two technologies are studied for off-road diesel engine NOx emission reductions: stoichiometric combustion ignition (SCI) and lean NOx trap (LNT). The concept of the stoichiometric compression ignition (SCI) engine was investigated for implementation in a turbocharged diesel engine through co-simulation. At first, an integrated environment for 1D engine modeling with control function was proposed for a SCI performance evaluation and control implementation. The SCI engine has been evaluated by Constant Speed Load Acceptance tests under steady-state and transient conditions. For SCI implementations, basic controls have been designed including air-fuel ratio (AFR) control, torque limiting control and idle speed control. The proposed control strategies have been verified with 1D detail models in the integrated environments. Further, the Mean Value Engine Model (MVEM) is proposed for advanced model based control design. The SCI engine subsystems are modeled using an orifice constrain model for throttle, turbine, and wastegate; filling and emptying model for intake and exhaust manifolds; rotational dynamic for engine camshaft and turbocharger shift, air-charging model and exhaust properties regressed by the data from integrated simulation at different engine operating conditions. The MVEM was implemented in Matlab/Simulink for verification. Modular and system verification was conducted for steady-state and transient state consistency with the 1D detail model. The results are promising, but the whole system needs further tuning for dynamic control design. The lean-NOx trap, as an alternative after-treatment for NOx control, has been studied for generic diesel engine emission control. Based on experimental data, an improved NOx adsorption model is proposed for integrated engine control and optimization.
Book Synopsis Reduction of the emissions in gas-diesel engines by :
Download or read book Reduction of the emissions in gas-diesel engines written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Neste estudo, os esforços são concentrados em se buscar a redução dasemissões em motores Diesel-gás. Assim, são apresentados resultadosexperimentais, obtidos em dinamômetro de bancada, das emissões e desempenhode um motor do ciclo Diesel (turbo alimentado e com intercooler), para operar, reversivelmente, como motor Diesel-gás ou Diesel original. Inicialmente, foramexecutados ensaios nas duas versões, Diesel e Diesel-gás; logo, os resultadosrespectivos foram comparados em termos de emissões e desempenho do motor. Aseguir, na operação Diesel-gás, foi avaliado o método da restrição parcial do ar deadmissão, a fim de produzir uma mistura efetivamente mais rica para a mesmaquantidade do gás natural. Os resultados obtidos mostraram uma notável reduçãonas emissões de monóxido de carbono e hidrocarbonetos não queimados, paratoda a faixa de operação avaliada. Por outro lado, as emissões de materialparticulado continuaram sendo ínfimas em altas taxas de substituição e os níveisde óxidos de nitrogênio apresentaram certo incremento em altas cargas do motor. Quanto ao rendimento térmico, verificam-se acréscimos quando é alcançado certovalor de taxa de substituição. Contudo, os resultados de emissões e rendimentotérmico apresentam melhores resultados em baixas cargas do motor (abaixo de50% da plena carga). Assim, além de reduzirem-se os níveis de certas emissõesem altas cargas, verificou-se uma contribuição adicional do presente trabalho noque diz respeito à redução, de forma parcial, de um dos principais problemasenvolvendo a combustão em motores Diesel-gás: a queima incompleta de misturaspobres em cargas baixas.
Book Synopsis Optimizing the Performance and Emissions of an Advanced Diesel Engine for Dual Fuel Operation by : M Muralidharan
Download or read book Optimizing the Performance and Emissions of an Advanced Diesel Engine for Dual Fuel Operation written by M Muralidharan and published by Mohammed Abdul Sattar. This book was released on 2024-03-24 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Energy is widely regarded as one of the key contributors to economic development and personal comfort. Economic expansion and energy use are closely related to one another. The availability of affordable, environmentally acceptable energy sources is necessary for the growth of an economy and for it to remain competitive on a global scale. Conversely, the level of economic development is considered to be affected by energy consumption. Due to rising population and economic development, consumption has recently increased. We are fortunate to have both moderate and renewable energy resources. We lack resources with a high energy density, such as nuclear power plants and fossil fuels. Diesel engines have slowly become more popular over the past century as a fuel-efficient and dependable form of transportation for commodities and the general public, as well as for other essential social needs, including small-scale power generation and other similar activities. They often have advantages over spark-ignition engines due to their reduced regulated emissions of CO, unburned HC & carbon dioxide (CO2) and better thermal efficiency. Diesel engines also have the advantage of using low-energy alternative fuels like biogas since they can run at a higher compression ratio. On the other hand, diesel engines generate dangerous pollutants, including PM and NOx. Because of their potential health hazards and effect on visibility, these emissions are a hazard. When exposed, particulate emissions have the potential to cause occupational cancer and have a number of other negative health effects. Diesel engines, when used as part of a transportation system, are widely acknowledged as a significant source of ambient particulate matter. Natural gas, a widely recognized gaseous alternative fuel, consists of various gas species and is derived from fossil sources. It is possible to find fossil natural gas either by itself or in conjunction with other fossil fuels (eg, coal in coal beds and crude oil in oil fields). Natural gas's properties are fundamentally identical to those of methane (CH4) which is its principal composition.
Book Synopsis Diesel Combustion and Emissions by : Society of Automotive Engineers
Download or read book Diesel Combustion and Emissions written by Society of Automotive Engineers and published by . This book was released on 1981 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Performance Evaluation and Optimization of Diesel Fuel Properties and Chemistry in an HCCI Engine by :
Download or read book Performance Evaluation and Optimization of Diesel Fuel Properties and Chemistry in an HCCI Engine written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The nine CRC fuels for advanced combustion engines (FACE fuels) have been evaluated in a simple, premixed HCCI engine under varying conditions of fuel rate, air-fuel ratio, and intake temperature. Engine performance was found to vary mainly as a function of combustion phasing as affected by fuel cetane and engine control variables. The data was modeled using statistical techniques involving eigenvector representation of the fuel properties and engine control variables, to define engine response and allow optimization across the fuels for best fuel efficiency. In general, the independent manipulation of intake temperature and air-fuel ratio provided some opportunity for improving combustion efficiency of a specific fuel beyond the direct effect of targeting the optimum combustion phasing of the engine (near 5 CAD ATDC). High cetane fuels suffer performance loss due to easier ignition, resulting in lower intake temperatures, which increase HC and CO emissions and result in the need for more advanced combustion phasing. The FACE fuels also varied in T90 temperature and % aromatics, independent of cetane number. T90 temperature was found to have an effect on engine performance when combined with high centane, but % aromatics did not, when evaluated independently of cetane and T90.
Book Synopsis Implementation and Control of Stoichiometric Natural Gas Combustion to Enable Low-emission Diesel Engines by : Nathaniel Bryce Oliver
Download or read book Implementation and Control of Stoichiometric Natural Gas Combustion to Enable Low-emission Diesel Engines written by Nathaniel Bryce Oliver and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The expected growth in the heavy-duty transportation sector necessitates the development of engine technologies able to increase efficiency and reduce emissions without sacrificing power output. Previous research has demonstrated that reducing heat transfer losses from the cylinder can enable significant efficiency gains in Diesel engines. The high in-cylinder temperatures generated in this engine architecture enable the use of low-cetane fuels with the potential for low-soot operation. Low soot emissions allow the equivalence ratio to be increased to stoichiometric which increases power, and could allow the existing Diesel aftertreatment system to be replaced with a less-expensive three-way catalyst. Natural gas is a promising candidate for stoichiometric, high-temperature, Diesel-style combustion. Its high hydrogen-to-carbon ratio should be able to reduce both soot and carbon dioxide emissions, and its wide distribution as a commercial and residential fuel provides existing infrastructure to speed deployment in transportation applications. This thesis demonstrates stoichiometric, Diesel-style combustion of neat methane as a single-component surrogate for natural gas. It explores the challenges of injecting a gaseous fuel at high pressures, and demonstrates the fuel's capacity for low emissions. It then provides a preliminary investigation into multiple-injection strategies for controlling combustion behavior and emissions in a stoichiometric, high-temperature engine architecture. First, fuel system hardware is developed to enable gaseous operation and preliminary experimentation is accomplished with methane. A fuel compression system is designed to supply methane at pressures suitably high to achieve good mixing and short injection durations, and a solenoid-actuated Diesel fuel injector is modeled and modified to inject methane at these pressures. This fuel injection system is then implemented on a single-cylinder engine. An insulated piston face, air cooled head, and intake preheating achieve suitable start of injection temperatures to ignite methane. Intake preheating is varied at low equivalence ratios to determine the sensitivity of engine performance to temperature at the lowest-load, lowest-temperature conditions of interest. A sweep of equivalence ratio demonstrates soot emissions roughly four times the current EPA limit for heavy-duty vehicles and combustion efficiencies of approximately 92% at stoichiometric fuel loading. High soot levels and low combustion efficiencies are also seen at the lowest equivalence ratios investigated. This suggests poorly mixed combustion, and poor injector performance. Second, injector dynamics are examined in greater detailed, and emissions performance is characterized with improved injector performance. High-speed Schlieren imaging is able to determine the injection dynamics contributing to high low-load emissions. A parametric modeling investigation suggests that reducing the injector plunger length is able to remove flow rate oscillations seen at long injection durations, and that the addition of dry friction is able to reduce the magnitude of low-momentum post injections occurring after injector closing. Dry friction is implemented using PTFE O-rings installed between the injector body and plunger. Imaging is used to confirm that a shortened plunger is able to remove long-duration oscillations, and to determine the number of O-rings necessary to suitably reduce post injection magnitude. The improved injector is used to repeat the sweep of equivalence ratios and demonstrates improved soot emissions at all operating conditions. Most notably, low-load soot emissions are reduced by more than a factor of ten, demonstrating the effectiveness of improved injector performance for improving emissions. Techniques for further improving injector performance and potential changes to injector design are discussed. Finally, the prospects for controlling combustion in a stoichiometric, low heat rejection Diesel engine using multiple injections are discussed and experimentally investigated. The applications and effects of multiple injection strategies in traditional Diesel engines are explored, and their potential extension to stoichiometric engines is discussed. Methanol engine operation enables the use of a fast-actuating piezoinjector and the realization of short injection pulses. A range of two-injection strategies are implemented in order to determine the sensitivity of engine operation to pilot, split-main, and post-injection timing and duration. Small pilot injections are found to have control authority over rate of pressure rise and peak pressure and show some promise for improving combustion efficiency. Post injections demonstrate authority over peak pressure and combustion efficiency. All of these effects are accomplished with minimal impact on engine work output. The experiments of this thesis demonstrate that, even with course control of injection, high-temperature, stoichiometric combustion of methane is able to greatly reduce soot emissions over traditional Diesel engines. Improved injector dynamics and the implementation of multiple injection strategies further improve emissions and combustion performance, suggesting substantial room for refinement of the technology and motivating the continued development of injector hardware and injection strategies. The ability to operate a Diesel engine at stoichiometric fueled only by natural gas and to employ a three-way catalyst for emissions abatement makes this strategy a clean, efficient, high-torque, and low-cost solution for heavy-duty transportation.
