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Low Heat Capacitance Thermal Barrier Coatings for Internal Combustion Engines

Adiabatics Inc.-Lloyd S. Kamo, Alex Kamo
Briggs & Stratton-David Procknow
Published 2019-04-02 by SAE International in United States
A new generation of low heat capacitance Thermal Barrier Coatings (TBCs) has been developed under U.S. Dept. of Energy / Advanced Research Projects Agency - Energy (ARPA-E) sponsored research. The TBCs developed under this project have significantly lower thermal conductivity of < 0.35 W/m-K, thermal heat capacitance of < 500 kJ/m3-K, and density of <0.35 g/cm3. Two different binder types were used for thermal barrier coatings applied by High Velocity Low Pressure (HVLP) spraying to the piston, cylinder head, and valve combustion surfaces of a small natural gas engine. The effects of thermal barrier coatings on engine efficiency and knock characteristics were studied in a small, high compression ratio, spark-ignition, internal combustion engine operating on methane number fuels from 60 to 100. The new TBCs with low thermal conductivity and low thermal heat capacities have been shown to increase overall engine efficiency through reduced heat transfer to the piston and cylinder head. These improved TBC properties resulted in 1.3% improved thermal efficiency or a 4.6% reduction in fuel consumption on the natural gas engine through…
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Numerical Optimization of the Combustion System of a HD Compression Ignition Engine Fueled with DME Considering Current and Future Emission Standards

Universitat Politecnica de Valencia-Jesus Benajes, Ricardo Novella, Alberto Hernández-López
University of Wisconsin Madison-Sage Kokjohn
Published 2018-04-03 by SAE International in United States
A genetic algorithm (GA) optimization methodology is applied to the design of the combustion system of a heavy-duty (HD) Diesel engine fueled with dimethyl ether (DME). The study has two objectives, the optimization of a conventional diffusion-controlled combustion system aiming to achieve US2010 targets and the optimization of a stoichiometric combustion system coupled with a three way catalyst (TWC) to further control NOx emissions and achieve US2030 emission standards. These optimizations include the key combustion system related hardware, bowl geometry and injection nozzle design as input factors, together with the most relevant air management and injection settings. The GA was linked to the KIVA CFD code and an automated grid generation tool to perform a single-objective optimization. The target of the optimizations is to improve net indicated efficiency (NIE) while keeping NOx emissions, peak pressure and pressure rise rate under their corresponding target levels. Compared to the baseline engine fueled with DME, the results of the study provide an optimum conventional diesel combustion system with 3.3% NIE improvement and an optimum stoichiometric combustion system that…
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Performance of Gasoline Compression Ignition (GCI) with On-Demand Reactivity Enhancement over Simulated Drive Cycles

ARC Mechatronics LLC-Yiqun Huang
QuantLogic Corporation-Deyang Hou
Published 2018-04-03 by SAE International in United States
Gasoline compression ignition (GCI) combustion is a promising solution to address increasingly stringent efficiency and emissions regulations imposed on the internal combustion engine. However, the high resistance to auto-ignition of modern market gasoline makes low load compression ignition (CI) operation difficult. Accordingly, a method that enables the variation of the fuel reactivity on demand is an ideal solution to address low load stability issues. Metal engine experiments conducted on a single cylinder medium-duty research engine allowed for the investigation of this strategy. The fuels used for this study were 87 octane gasoline (primary fuel stream) and diesel fuel (reactivity enhancer). Initial tests demonstrated load extension down to idle conditions with only 20% diesel by mass, which reduced to 0% at loads above 3 bar IMEPg. Engine performance over a mode weighted drive cycle was completed based on work by the Ad-Hoc fuels committee [1] to demonstrate the performance of various levels of fuel blending for five primary modes of operation encompassing low load to high load. Lastly, several simulated transient drive cycle were analyzed to investigate…
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Reformed Fuel Substitution for Transient Peak Soot Reduction

University of Wisconsin Madison-Flavio Dal Forno Chuahy, Jamen Olk, Sage Kokjohn
Published 2018-04-03 by SAE International in United States
Advancements in catalytic reforming have demonstrated the ability to generate syngas (a mixture of CO and hydrogen) from a single hydrocarbon stream. This syngas mixture can then be used to replace diesel fuel and enable dual-fuel combustion strategies. The role of port-fuel injected syngas, comprised of equal parts hydrogen and carbon monoxide by volume was investigated experimentally for soot reduction benefits under a transient load change at constant speed. The syngas used for the experiments was presumed to be formed via a partial oxidation on-board fuel reforming process and delivered through gaseous injectors using a custom gas rail supplied with bottle gas, mounted in the swirl runner of the intake manifold. Time-based ramping of the direct-injected fuel with constant syngas fuel mass delivery from 2 to 8 bar brake mean effective pressure was performed on a multi-cylinder, turbocharged, light-duty engine to determine the effects of syngas on transient soot emissions. A Cambustion fNOx400 high-speed emissions analyzer and an AVL 439 opacimeter were used to quantify emissions under the load change to provide sub-cycle and cycle resolved…
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Gasoline Compression Ignition Operation of a Heavy-Duty Engine at High Load

University of Wisconsin Madison-Jordan Paz, Dan Staaden, Sage Kokjohn
Published 2018-04-03 by SAE International in United States
Engine experiments were carried out on a heavy-duty single-cylinder engine to investigate the effects of Gasoline Compression Ignition on emissions and performance of a heavy-duty engine operating at a high load condition. Comparisons between gasoline fueled operation and diesel fueled operation are presented using a single, near top dead center injection. Although the fuel’s cetane numbers are very different, the combustion characteristics of the two fuels at high load are similar, with the gasoline-fueled case showing less than two crank angle degree longer ignition delay. Gasoline operation showed lower soot production at similar levels of NOx, initiating study of the impact of exhaust gas recirculation which spanned a range of NOx levels covering the range from minimal urea dosing to high urea dosing. A conventional soot-NOx tradeoff was found to exist with gasoline as exists with diesel. For the gasoline-fueled cases, the impact of premixed fuel was investigated and the tradeoffs between particulate matter (soot) and peak pressure rise rate is discussed. As the amount of premixed fuel is increased, the trend of increasing peak…
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System and Second Law Analysis of the Effects of Reformed Fuel Composition in “Single” Fuel RCCI Combustion

SAE International Journal of Engines

Flavio Dal Forno Chuahy
University of Wisconsin Madison-Sage Kokjohn
  • Journal Article
  • 2018-01-0264
Published 2018-04-03 by SAE International in United States
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 limits practical application. Advancements in catalytic reforming have demonstrated the ability to generate syngas (a mixture of CO and hydrogen) from a single hydrocarbon stream. This syngas mixture can then be used as the low reactivity fuel stream to enable single fuel RCCI combustion. The present effort uses a combination of engine experiments and system level modeling to investigate reformed fuel RCCI combustion. The impact of reformer composition is investigated by varying the syngas composition from 10% H2 to approximately 80% H2. The results of the investigation show that reformed fuel RCCI combustion is possible over a wide range of H2/CO ratios. A system level and second law analysis are performed on the highest efficiency operating points, and comparisons are made between partial oxidation reforming, steam reforming, and conventional diesel. The results show that endothermic reforming (steam reforming) can achieve comparable system level efficiency to…
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The Effects of Charge Preparation, Fuel Stratification, and Premixed Fuel Chemistry on Reactivity Controlled Compression Ignition (RCCI) Combustion

SAE International Journal of Engines

Oakland University-Dan DelVescovo
University of Wisconsin-Sage Kokjohn, Rolf Reitz
  • Journal Article
  • 2017-01-0773
Published 2017-03-28 by SAE International in United States
Engine experiments were conducted on a heavy-duty single-cylinder engine to explore the effects of charge preparation, fuel stratification, and premixed fuel chemistry on the performance and emissions of Reactivity Controlled Compression Ignition (RCCI) combustion. The experiments were conducted at a fixed total fuel energy and engine speed, and charge preparation was varied by adjusting the global equivalence ratio between 0.28 and 0.35 at intake temperatures of 40°C and 60°C. With a premixed injection of isooctane (PRF100), and a single direct-injection of n-heptane (PRF0), fuel stratification was varied with start of injection (SOI) timing. Combustion phasing advanced as SOI was retarded between -140° and -35°, then retarded as injection timing was further retarded, indicating a potential shift in combustion regime. Peak gross efficiency was achieved between -60° and -45° SOI, and NOx emissions increased as SOI was retarded beyond -40°, peaking around -25° SOI. Optimal cases in terms of both gross efficiency and peak pressure rise rate (PPRR) were in the mid-range SOI timings centered about -50° SOI, while late SOI resulted in decreased gross efficiency,…
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Investigating Air Handling Requirements of High Load Low Speed Reactivity Controlled Compression Ignition (RCCI) Combustion

University of Wisconsin-Madison-Chaitanya Kavuri, Sage Kokjohn
Published 2016-04-05 by SAE International in United States
Past research has shown that reactivity controlled compression ignition (RCCI) combustion offers efficiency and NOx and soot advantages over conventional diesel combustion at mid load conditions. However, at high load and low speed conditions, the chemistry timescale of the fuel shortens and the engine timescale lengthens. This mismatch in timescales makes operation at high load and low speed conditions difficult. High levels of exhaust gas recirculation (EGR) can be used to extend the chemistry timescales; however, this comes at the penalty of increased pumping losses. In the present study, targeting the high load - low speed regime, computational optimizations of RCCI combustion were performed at 20 bar gross indicated mean effective pressure (IMEP) and 1300 rev/min. The two fuels used for the study were gasoline (low reactivity) and diesel (high reactivity). The effects of intake pressure and EGR on combustion and emissions were studied using a full factorial design of experiments of genetic algorithm optimizations. The optimizations were setup for three values of EGR (30%, 45% and 55%) and equivalence ratios (0.8, 0.9 and 1.0).…
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The Development of an Ignition Delay Correlation for PRF Fuel Blends from PRF0 (n-Heptane) to PRF100 (iso-Octane)

SAE International Journal of Engines

University of Wisconsin-Dan DelVescovo, Sage Kokjohn, Rolf Reitz
  • Journal Article
  • 2016-01-0551
Published 2016-04-05 by SAE International in United States
A correlation was developed to predict the ignition delay of PRF blends at a wide range of engine-relevant operating conditions. Constant volume simulations were performed using Cantera coupled with a reduced reaction mechanism at a range of initial temperatures from 570-1860K, initial pressures from 10-100atm, oxygen mole percent from 12.6% to 21%, equivalence ratios from 0.30-1.5, and PRF blends from PRF0 to PRF100. In total, 6,480 independent ignition delay simulations were performed.The correlation utilizes the traditional Arrhenius formulation; with equivalence ratio (φ), pressure (p), and oxygen mole percentage (xo2) dependencies. The exponents α, β, and γ were fitted to a third order polynomial with respect to temperature with an exponential roll-off to a constant value at low temperatures to capture the behavior expressed by the reaction mechanism. The location and rate of the roll-off functions were modified by linear functions of PRF. The activation energy term, λ is expressed as a combination of a third and second order polynomial with respect to temperature with an exponential roll-off function whose location and rate varied with a…
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ERRATUM: The Development of an Ignition Delay Correlation for PRF Fuel Blends from PRF0 (n-Heptane) to PRF100 (iso-Octane)

SAE International Journal of Engines

University of Wisconsin-Dan DelVescovo, Sage Kokjohn, Rolf D. Reitz
  • Journal Article
  • 2016-01-0551.01
Published 2016-04-05 by SAE International in United States
In Equation 10, there should be a plus sign between the first summation term and the quantity in brackets. The acceleration of the participant's vehicle was varied from −0.04 m/s2 to +0.06 m/s2 linearly as a function of the angle of the gas pedal with a 0.1-second delay.
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