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Technical Paper

Hydrocarbon Speciation in Blended Gasoline-Natural Gas Operation on a Spark-Ignition Engine

2016-10-17
2016-01-2169
The high octane rating and more plentiful domestic supply of natural gas make it an excellent alternative to gasoline. Recent studies have shown that using natural gas in dual fuel engines provides one possible strategy for leveraging the advantages of both natural gas and gasoline. In particular, such engines been able to improve overall engine efficiencies and load capacity when they leverage direct injection of the natural gas fuel. While the benefits of these engine concepts are still being explored, differences in fuel composition, combustion process and in-cylinder mixing could lead to dramatically different emissions which can substantially impact the effectiveness of the engine’s exhaust aftertreatment system. In order to explore this topic, this study examined the variations in speciated hydrocarbon emissions which occur for different fuel blends of E10 and compressed natural gas and for different fuel injection strategies on a spark-ignition engine.
Technical Paper

A Gasoline Fuelled Pre-Chamber Ignition System for Homogeneous Lean Combustion Processes

2016-10-24
2016-01-2176
Pre-chamber ignition systems enable the combustion of homogeneous lean mixtures in internal combustion engines with significantly increased thermal efficiency. Such ignition systems provide a much higher ignition energy compared to a common spark ignition by burning a small portion of the charge in a separate chamber, generating multiple ignition sites in the main combustion chamber and increasing the turbulent flame speed. Pre-chamber ignition systems are commonly used in large natural gas engines but the integration in automotive engines is not feasible so far due to the lack of suitable fuelling systems needed to keep the pre-chamber mixture stoichiometric at lean operation of the engine. Based on preliminary investigations we developed an ignition system with fuelled pre-chamber for automotive engines utilizing the available space for the conventional spark plug.
Technical Paper

Sound and Vibration Levels of CI Engine with Synthetic Kerosene and n-Butanol in RCCI

2016-04-05
2016-01-1306
Diesel engines provide the necessary power for accomplishing heavy tasks across the industries, but are known to produce high levels of noise. Additionally, each type of fuel possesses unique combustion characteristics that lead to different sound and vibration signatures. Noise is an indication of vibration, and components under excessive vibration may wear prematurely, leading to repair costs and downtime. New fuels that are sought to reduce emissions, and promote sustainability and energy independence must be investigated for compatibility from a sound and vibrations point-of-view also. In this research, the sound and vibration levels were analyzed for an omnivorous, single cylinder, CI research engine with alternative fuels and an advanced combustion strategy, RCCI. The fuels used were ULSD#2 as baseline, natural gas derived synthetic kerosene, and a low reactivity fuel n-Butanol for the PFI in the RCCI process.
Technical Paper

Optimisation of Expansion Ratio of an Advanced Compressed Air Engine Kit

2016-04-05
2016-01-1283
Worldwide, research is going on numerous types of engines that practice green and alternative energy such as natural gas engines, hydrogen engines, and electric engines. One of the possible alternatives is the air powered car. Air is abundantly available and can be effortlessly compressed to higher pressure at a very low cost. After the successful development of Compressed Air Engines, engineers shifted their focus in making this technology cost effective and feasible. This led to advancement in the field of pneumatics that is advanced Compressed Air Engine Kit (used for conversion of a small-two stroke SI engine to Compressed Air Engine) where its frugality and compatibility is kept at high priority. This research is in continuation with our previous project of development of an advanced Compressed Air Engine kit and optimisation of injection angle and injector nozzle area for maximum performance.
Technical Paper

Critical Factors in the Development of Well-To-Wheel Analyses of Alternative Fuel and Advanced Powertrain Heavy-Duty Vehicles

2016-04-05
2016-01-1284
A heavy-duty vehicle (HDV) module of the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREETTM) model has been developed at Argonne National Laboratory. The fuel-cycle GREET model has been published extensively and contains data on fuel-cycles and vehicle operation of light-duty vehicles. The addition of the HDV module to the GREET model allows for well-to-wheel (WTW) analyses of heavy-duty advanced technology and alternative fuel vehicles (AFVs), which has been lacking in the literature. WTW analyses of HDVs becomes increasingly important to understand the fuel consumption and greenhouse gas (GHG) emissions impacts of newly enacted and future HDV regulations from the Environmental Protection Agency and the Department of Transportation’s National Highway Traffic Safety Administration.
Technical Paper

Investigations on the effect of Piston Squish Area on Performance and Emission Characteristics of LPG fuelled Lean Burn SI Engine

2016-02-01
2016-28-0121
Experiments were conducted to study the effects of piston squish area on the performance, emissions and combustion characteristics of a Liquefied Petroleum Gas (LPG) fuelled lean burn Spark Ignition (SI) engine at a compression ratio of 10:1 under 25% throttle condition. A single cylinder diesel engine was modified to operate as LPG fuelled SI engine at a constant speed of 1500 rpm. The test was conducted at different squish areas of 25, 30, 35 and 40% on the total piston area at different equivalence ratios maintaining a constant squish velocity of 4 m/s. The ignition timing was set to MBT (Minimum advance for best Torque). It has been found that there is no significant change in lean limit in all the squish areas. An appreciable difference in brake power and brake thermal efficiency was noticed between equivalence ratios 0.7 and 0.9. The piston with 30% squish area showed good results followed by 25, 35 and 40%.
Technical Paper

Optimizing and Validating the Engine Performance and Emission Parameters on Engine Dynamometer through 1D Simulation of a Multi-Cylinder CNG Engine

2016-02-01
2016-28-0100
Environmental pollution has proven to be a big threat to our eco-system and pollution from automobiles using conventional fuels is a major contributor to this. Alternative fuels are the only immediate option that can help us counter the ever rising environmental pollution. In today’s date we cannot directly replace an IC engine, so the most efficient option available is using a fuel that can work with the IC engines other than gasoline and diesel. CNG proves to be the most promising fuel. A diesel engine converted to stoichiometric CNG engine was used for optimization. The paper deals with the improvement of engine power from 50HP to 60HP and up-gradation of the emission from BS-III to BS-IV norms of a multi-cylinder naturally aspirated engine. This was achieved by varying the compression ratio, valve-lift profile, intake plenum volume, runner length, spark-advance timing, fuel injection location, exhaust pipe length and catalytic converter selection.
Journal Article

Influence of Binary CNG Substitute Composition on the Prediction of Burn Rate, Engine Knock and Cycle-to-Cycle Variations

2017-03-28
2017-01-0518
Since 0D/1D-simulations of natural gas spark ignition engines use model theories similar to gasoline engines, the impact of changing fuel characteristics needs to be taken into consideration in order to obtain results of higher quality. For this goal, this paper proposes some approaches that consider the influence of binary fuel mixtures such as methane with up to 40 mol-% of ethane, propane, n-butane or hydrogen on laminar flame speed and knock behavior. To quantify these influences, reaction kinetics calculations are carried out in a wide range of the engine operation conditions. Obtained results are used to update and extend existing sub-models. The model quality is validated by comparing measured burn rates with simulation results. The benefit of the new sub-models are utilized by predicting the influence the fuel takes on engine operating limits in terms of knocking and lean misfire limits, the latter being determined by using a cycle-to-cycle variation model.
Journal Article

Development and Validation of a Quasi-Dimensional Dual Fuel (Diesel – Natural Gas) Combustion Model

2017-03-28
2017-01-0517
This paper presents a newly developed quasi-dimensional multi-zone dual fuel combustion model, which has been integrated within the commercial engine system simulation framework. Model is based on the modified Multi-Zone Combustion Model and Fractal Combustion Model. Modified Multi-Zone Combustion Model handles the part of the combustion process that is governed by the mixing-controlled combustion, while the modified Fractal Combustion Model handles the part that is governed by the flame propagation through the combustion chamber. The developed quasi-dimensional dual fuel combustion model features phenomenological description of spray processes, i.e. liquid spray break-up, fresh charge entrainment, droplet heat-up and evaporation process. In order to capture the chemical effects on the ignition delay, special ignition delay table has been made.
Technical Paper

Fast Exhaust Nephelometer (FEN): A New Instrument for Measuring Cycle-Resolved Engine Particulate Emission

2016-10-17
2016-01-2329
Soot emissions from direct-injection engines are sensitive to the fuel-air mixing process, and may vary between combustion cycles due to turbulence and injector variability. Conventional exhaust emissions measurements cannot resolve inter- or intra-cycle variations in particle emissions, which can be important during transient engine operations where a few cycles can disproportionately affect the total exhaust soot. The Fast Exhaust Nephelometer (FEN) is introduced here to use light scattering to measure particulate matter concentration and size near the exhaust port of an engine with a time resolution of better than one millisecond. The FEN operates at atmospheric pressure, sampling near the engine exhaust port and uses a laser diode to illuminate a small measurement volume. The scattered light is focused on two amplified photodiodes.
Technical Paper

Feedforward Control of Fuel Distribution on Advanced Dual-Fuel Engines with Varying Intake Valve Closing Timings

2016-10-17
2016-01-2312
This study examines the dynamics and control of an engine operated with late intake valve closure (LIVC) timings in a dual-fuel combustion mode. The engine features a fuel delivery system in which diesel is direct-injected and natural gas is port-injected. Despite the benefits of LIVC and dual-fuel strategy, combining these two techniques resulted in efficiency losses due to the variability of the combustion process across cylinders. The difference in power production across cylinders ranges from 9% at an IVC of 570°ATDC* to 38% at an IVC of 620 °ATDC and indicates an increasingly uneven fuel distribution as the intake valve remains open longer in the compression stroke. This paper describes an approach for controlling the amount of fuel injected into each cylinders’ port of an inline six- cylinder heavy-duty dual-fuel engine to minimize the variations in fuel distribution across cylinder.
Technical Paper

Application of an In-Cylinder Local Infrared Absorption Fuel Concentration Sensor in a Diesel-Ignited Dual-Fuel Engine

2016-10-17
2016-01-2310
As global energy demands continue to be met with ever evolving and stricter emissions requirements, natural gas (NG) has become a highly researched alternative to conventional fossil fuels in many industrial sectors. Transportation is one such field that can utilize the benefits of NG as a primary fuel for use in internal combustion engines (ICEs). In the context of heavy-duty on-highway transportation applications, diesel-ignited dual-fuel (DIDF) combustion of NG has been identified as a commercially viable alternative technology. Previous investigations of DIDF have examined the various trends present across the spectrum of DIDF operating space. However, in-cylinder processes are still not well understood and this investigation aims to further understanding in this area. An in-cylinder, local infrared absorption fuel concentration sensor is used to examine in-cylinder processes by comparison with previous optical and thermodynamic studies.
Technical Paper

Investigation on Dual Fuel Engine Gas Combustion using Tomographic In-Cylinder Measurement Technique and Simultaneous High Speed OH-Chemiluminescence Visualization

2016-10-17
2016-01-2308
Strict emission regulations and the need of higher efficiency of future dual fuel engines require an optimized combustion process. For getting a better understanding of the in-cylinder combustion process optical investigations represent a powerful tool. For medium speed dual fuel engines, optical investigations are pretty rare respectively not available. Especially the avoiding of knock events within the combustion process is a key development topic to realize high engine load and high engine efficiency. For the investigations a fully flexible dual fuel test engine was used. The engine is operated with a natural gas / air cylinder charge which is ignited by a small micro pilot diesel injection within the gas mode.
Technical Paper

Efficiency and Emissions Mapping of a Light Duty Diesel - Natural Gas Engine Operating in Conventional Diesel and RCCI Modes

2016-10-17
2016-01-2309
Reactivity Controlled Compression Ignition (RCCI) is a promising dual-fuel Low Temperature Combustion (LTC) mode with significant potential for reducing NOx and particulate emissions while improving or maintaining thermal efficiency compared to Conventional Diesel Combustion (CDC) engines. The large reactivity difference between diesel and Natural Gas (NG) fuels provides a strong control variable for phasing and shaping combustion heat release. In this work, the Brake Thermal Efficiencies (BTE), emissions and combustion characteristics of a light duty 1.9L, four-cylinder diesel engine operating in single fuel diesel mode and in Diesel-NG RCCI mode are investigated and compared. The engine was operated at speeds of 1300 to 2500 RPM and loads of 1 to 7 bar BMEP. Operation was limited to 10 bar/deg Maximum Pressure Rise Rate (MPRR) and 6% Coefficient of Variation (COV) of IMEP.
Technical Paper

Performance Improvements in a Natural Gas Dual Fuel Compression Ignition Engine with 250 MPa Pilot Injection of Diesel Fuel as an Ignition Source

2016-10-17
2016-01-2307
The engine performance and the exhaust gas emissions in a dual fuel compression ignition engine with natural gas as the main fuel and a small quantity of pilot injection of diesel fuel with the ultra-high injection pressure of 250 MPa as an ignition source were investigated at 0.3 MPa and 0.8 MPa IMEP. With increasing injection pressure the unburned loss decreases and the thermal efficiency improves at both IMEP conditions. At the 0.3 MPa IMEP the THC and CO emissions are significantly reduced when maintaining the equivalence ratio of natural gas with decreasing the volumetric efficiency by intake gas throttling, but the NOx emissions increase and excessive intake gas throttling results in a decrease in the indicated thermal efficiency. Under the 250 MPa pilot injection condition simultaneous reductions in the NOx, THC, and CO emissions can be established with maintaining the equivalence ratio of natural gas by intake gas throttling.
Technical Paper

Analysis of a Dual-Fuel Combustion Engine Fueled with Diesel Fuel and CNG in Transient Operating Conditions

2016-10-17
2016-01-2305
The paper presents the thermodynamic analysis of the engine supplied with small and large diesel fuel doses while increasing natural gas quantity. The paper presents changes in the combustion process thermodynamic indexes and changes in the exhaust gas emissions for dynamically increased share of the gaseous fuel. The cylinder pressure history was subject to thermodynamic analysis, . based on which the mean indicated pressure, the heat release rate, the quantity of heat released as well as the pressure rate increase after self-ignition were determined. These parameters were also referred to the subsequent engine operation cycles by specifying the scope of the change per cycle. The relationship between the engine load and the start, the center and the end of combustion while increasing the gas amount supplied to the cylinder was indicated.
Journal Article

Well-to-Wheels Emissions of Greenhouse Gases and Air Pollutants of Dimethyl Ether from Natural Gas and Renewable Feedstocks in Comparison with Petroleum Gasoline and Diesel in the United States and Europe

2016-10-17
2016-01-2208
Dimethyl ether (DME) is an alternative to diesel fuel for use in compression-ignition engines with modified fuel systems and offers potential advantages of efficiency improvements and emission reductions. DME can be produced from natural gas (NG) or from renewable feedstocks such as landfill gas (LFG) or renewable natural gas from manure waste streams (MANR) or any other biomass. This study investigates the well-to-wheels (WTW) energy use and emissions of five DME production pathways as compared with those of petroleum gasoline and diesel using the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET®) model developed at Argonne National Laboratory (ANL).
Technical Paper

Comparison of Pollutant Emissions from Common Platform Vehicles Operating on Alternative Fuels over a Range of Driving Cycles at Standard and Cold Ambient Temperatures

2016-10-17
2016-01-2216
Alternative fuels and power trains are expected to play an important role in reducing emissions of greenhouse gases (GHGs) and other pollutants. In this study, five light-duty vans, operating on alternative fuels and propulsion systems, were tested on a chassis dynamometer for emissions and efficiency. The vehicles were powered with Tier 2 gasoline, low blend ethanol (E10), compressed natural gas (CNG), liquefied petroleum gas (LPG), and an electric battery. Four test cycles were used representing city driving and cold-start (FTP-75), aggressive high speed driving (US06), free flow highway driving (HWFCT), and a combination of urban, rural, and motorway driving (WHVC). Tests were performed at a temperature of 22°C, with select tests at -7°C and -18°C. Exhaust emissions were measured and characterized including CO, NOX, THC, PM and CO2. On the FTP-75, WHVC, and US06 cycles additional exhaust emission characterization included N2O, and CH4.
Journal Article

Evaluation of Knock Behavior for Natural Gas - Gasoline Blends in a Light Duty Spark Ignited Engine

2016-10-17
2016-01-2293
The compression ratio is a strong lever to increase the efficiency of an internal combustion engine. However, among others, it is limited by the knock resistance of the fuel used. Natural gas shows a higher knock resistance compared to gasoline, which makes it very attractive for use in internal combustion engines. The current paper describes the knock behavior of two gasoline fuels, and specific incylinder blend ratios with one of the gasoline fuels and natural gas. The engine used for these investigations is a single cylinder research engine for light duty application which is equipped with two separate fuel systems. Both fuels can be used simultaneously which allows for gasoline to be injected into the intake port and natural gas to be injected directly into the cylinder to overcome the power density loss usually connected with port fuel injection of natural gas.
Journal Article

Comparison and Sensitivity Analysis of Turbulent Flame Speed Closures in the RANS G-Equation Context for Two Distinct Engines

2016-10-17
2016-01-2235
Three-dimensional reactive computational fluid dynamics (CFD) plays a crucial role in IC engine development tasks complementing experimental efforts by providing improved understanding of the combustion process. A widely adopted combustion model in the engine community for (partially) premixed combustion is the G-Equation where the flame front is represented by an iso-level of an arbitrary scalar G. A convective-reactive equation for this iso-surface is solved, for which the turbulent flame speed ST must be provided. In this study, the commonly used and well-established Damköhler approach is compared to a novel correlation, derived from an algebraic closure for the scalar dissipation of reaction progress as proposed by Kolla et al. [1].
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