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Chen, Jyh-Yuan
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Application of Corona Discharge Ignition in a Boosted Direct-Injection Single Cylinder Gasoline Engine: Effects on Combustion Phasing, Fuel Consumption, and Emissions

SAE International Journal of Engines

Sandia National Laboratories-Benjamin Wolk
University of California, Berkeley-Daniel I. Pineda, Jyh-Yuan Chen, Robert W. Dibble
  • Journal Article
  • 2016-01-9045
Published 2016-01-03 by SAE International in United States
The downsizing of internal combustion engines to increase fuel economy leads to challenges in both obtaining ignition and stabilizing combustion at boosted intake pressures and high exhaust gas recirculation dilution conditions. The use of non-thermal plasma ignition technologies has shown promise as a means to more reliably ignite dilute charge mixtures at high pressures. Despite progress in fundamental research on this topic, both the capabilities and operation implications of emerging non-thermal plasma ignition technologies in internal combustion engine applications are not yet fully explored. In this work, we document the effects of using a corona discharge ignition system in a single cylinder gasoline direct injection research engine relative to using a traditional inductive spark ignition system under conditions associated with both naturally aspirated (8 bar BMEP) and boosted (20 bar BMEP) loads at moderate (2000 rpm) and high (4000 rpm) engine speeds. Analysis of experimental results shows that relative to optimum load-speed equivalent baseline operation, using the corona discharge ignition system improves fuel economy by (1) reducing cycle-to-cycle variability, (2) promoting more complete combustion, and…
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A Model for Prediction of Knock in the Cycle Simulation by Detail Characterization of Fuel and Temperature Stratification

SAE International Journal of Engines

Univ of California-Jyh-Yuan Chen, Robert W. Dibble
Univ of Zagreb-Darko Kozarac, Rudolf Tomic, Ivan Taritas
  • Journal Article
  • 2015-01-1245
Published 2015-04-14 by SAE International in United States
Development of SI engines to further increase engine efficiency is strongly affected by the occurrence of engine knock. Engine knock has been widely investigated over the years and the main promoting parameters have been identified as load (temperature and pressure), mixture composition, engine speed, characteristic of the fuel, combustion chamber design, and etc. In this paper a new model for predicting engine knock in 0-D environment is presented. The model is based on the well-known approach of using a Livengood and Wu knock integral. Ignition delay data that are supplied to the knock integral are for specific fuel calculated by detail chemical kinetics and are comprised of low temperature heat release ignition delay and high temperature heat release ignition delay. Next, the cycle to cycle variations of engine and temperature stratification of the end gas have to be taken into account. For temperature stratification a new model is developed which is based on the detail analysis of specific CFD results of several engines at different operating conditions. The validation of the knock prediction model was…
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Fuel-Dithering Optimization of Efficiency of TWC on Natural Gas IC Engine

SAE International Journal of Engines

University of California-Xian Shi, Reinhard Seiser, Jyh-Yuan Chen, Robert Dibble, Robert Cattolica
  • Journal Article
  • 2015-01-1043
Published 2015-04-14 by SAE International in United States
Steady-state, transient and dithering characteristics of emission conversion efficiencies of three-way catalysts on natural gas IC engine were investigated experimentally on a single-cylinder CFR engine test bench. Steady-state runs were conducted as references for specific engine emission levels and corresponding catalyst capacities. The steady-state data showed that conversion of HC will be the major problem since conversion of HC was effective only for a very narrow range of exhaust mixture. Unsteady exploration runs with both lean-to-rich and rich-to-lean transitions were conducted. These results were interpreted with a time scale analysis, according to which a qualitative oxygen storage model was proposed featuring the difference between oxygen absorption and desorption rates on the palladium catalysts. Additionally this oxygen storage model also revealed information about parameter selection for dithering to achieve optimal emission operation where all three, HC (mostly CH4), CO and NOx are simultaneously reduced.Dithering with different midpoint Lambda values, frequencies and amplitudes were further investigated. The results showed that the optimal dithering Lambda midpoint resided in slightly rich engine charge. An optimal intermediate frequency was found…
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Characterization of Ion Signals under Ringing Conditions in an HCCI Engine

University of California at Berkeley-Samveg Saxena, Jyh-Yuan Chen, Robert W. Dibble
Published 2011-08-30 by SAE International in United States
The objective of this research is the characterization of ringing in HCCI engines based on in-cylinder ion signal measurements. A correlation is identified to quantify ringing intensity from ion signals by comparing ion and pressure signal characteristics under ringing conditions in an HCCI engine. The maximum ion rise rate (dIon/dtmax) is shown to be an excellent indicator of the maximum pressure rise rate (dP/dtmax), a factor which is very important to measure ringing intensity. The effects of changing bias voltage and ion sensing resistors are also explored for their effects upon the ion ringing intensity. The results show that the ion ringing intensity correlation is accurate at quantifying ringing across a range of HCCI engine operating conditions, including various equivalence ratios, combustion timings and intake pressures.
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Extending the Lean Stability Limits of Gasoline Using a Microwave-Assisted Spark Plug

Imagineering Inc.-Atsushi Nishiyama, Yuji Ikeda
Univ. of California-Berkeley-Anthony DeFilippo, Samveg Saxena, Vi Rapp, Robert Dibble, Jyh-Yuan Chen
Published 2011-04-12 by SAE International in United States
The extension of the lean stability limits of gasoline-air mixtures using a microwave-assisted spark plug has been investigated. Experiments are conducted on a 1200 RPM single-cylinder Waukesha Cooperative Fuel Research (CFR) engine at two compression ratios: 7:1 and 9:1; and four different levels of microwave energy input per cycle (prior to accounting for transmission losses): 0 mJ (spark only), 130 mJ, 900 mJ, and 1640 mJ. For various microwave energy inputs, the effects upon stability limits are explored by gradually moving from stoichiometric conditions to increasingly lean mixtures. The coefficient of variation (COVIMEP) of the indicated mean effective pressure (IMEP) is used as an indication of the stability limits.Specific characteristics of microwave-assisted ignition are identified. Microwave enhancement extends stability limits into increasingly lean regions, but slow and partial burning at the leanest mixtures curb efficiency gains. Microwave assistance decreases occurrence of misfire and partial-burn by increasing early heat release in very lean mixtures, but engine operation is unaffected at closer-to-stoichiometric conditions. Increasing microwave energy input can improve combustion characteristics as compared to low-energy microwave enhancement,…
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Maximizing Power Output in an Automotive Scale Multi-Cylinder Homogeneous Charge Compression Ignition (HCCI) Engine

Univ of California-Berkeley-Samveg Saxena, Jyh-Yuan Chen, Robert Dibble
Published 2011-04-12 by SAE International in United States
Experimental investigations were conducted on a multi-cylinder automotive scale HCCI engine in determining a strategy that yields high power output, sufficient for passenger vehicles. A 1.9L Volkswagen TDI, modified for HCCI operation, is used with a compression ratio of 17:1 and boost pressures between 1.0 and 2.0 bar absolute. Various equivalence ratios and combustion times are explored at 1800 RPM with commercial-grade gasoline. The effects of exhaust backpressure that would be caused by a turbocharger in production engines are also explored.The results reveal that the highest power output can be achieved with high boost pressures and high equivalence ratios, and highly delayed combustion timing for controlling ringing. The optimal power output conditions exist near the boundaries of ringing, peak in-cylinder pressure, misfire and controllability. The results of the highest power output condition are displayed for a single cylinder; however, similar trends were seen across all four cylinders of the HCCI engine. The maximum power output identified in this study exceeded 9 bar gross IMEP, and high indicated efficiency points (exceeding 40%) were also found. NOx…
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