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Simulation Analysis of Early and Late Miller Cycle Strategies Influence on Diesel Engine Combustion and Emissions

Jining Polytechnic-Xiuyuan Li
Tongji University-Shuai Yang, Xiaolin Yang, Haifeng Liu, Zhiwei Feng
  • Technical Paper
  • 2020-01-0662
To be published on 2020-04-14 by SAE International in United States
Based on the working model of a diesel engine, the influence of 2 Miller cycle strategies-Early Intake Valve Closure (EIVC) and Late Intake Valve Closure (LIVC) on the combustion and emissions of diesel engine was analyzed. Then the working condition of each Miller cycle strategies on the engine under the rated speed was optimized through the adjust of the valve timing, boost pressure and the injection timing. The research found that both delaying and advancing the closure timing of the intake valve can decrease the pressure and temperature during compression stroke, prolonging the ignition delay. However, due to the decrease of the working media inside the cylinder, the average in-cylinder temperature and soot emissions will increase, which can be alleviated by raising the boost pressure and the resulting compensation of the intake loss. The study found that together with increasing boost pressure and delaying injection timing, both EIVC and LIVC can reduce the NOx and soot emissions simultaneously. The simulation results show that while keeping the peak firing pressure the same as the original machine,…
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Numerical Parametric Study of a Six-Stroke Gasoline Compression Ignition (GCI) Engine Combustion- Part II

Hyundai Motor Co.-Kyoung-Pyo Ha, Hyeon Woo Kim
Michigan Technological University-Oudumbar Rajput, Youngchul Ra
  • Technical Paper
  • 2020-01-0780
To be published on 2020-04-14 by SAE International in United States
In order to extend the operability limit of the gasoline compression ignition (GCI) engine, as an avenue for low temperature combustion (LTC) regime, the effects of parametric variations of engine operating conditions on the performance of six-stroke GCI (6S-GCI) engine cycle are numerically investigated, using an in-house 3D CFD code coupled with high-fidelity physical sub-models along with the Chemkin library. The combustion and emissions were calculated using a skeletal chemical kinetics mechanism for a 14-component gasoline surrogate fuel. Authors' previous study highlighted the effects of the variation of injection timing and split ratio on the overall performance of the 6S-GCI engine and the unique mixing-controlled burning mode of the charge mixtures during the two additional strokes. As a continuing effort, the present study details the parametric studies of initial gas temperature, boost pressure, fuel injection pressure, compression ratio, and EGR ratio. The focus of this paper is on the impact of these parameters on the performance of the two additional strokes of the 6S-GCI cycle such that the extent of controllability of ignition, combustion, and…
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On-Engine Performance Evaluation of New-Concept Turbocharger Compressor Housing Design

Imperial College London-Ricardo F. Martinez-Botas
Mitsubishi Heavy Industries, Ltd.-Takao Yokoyama, Yutaka Fujita, Motoki Ebisu
  • Technical Paper
  • 2020-01-1012
To be published on 2020-04-14 by SAE International in United States
Following the market demands in finding the niche balance between engine performance and legislation requirement, a new compressor scroll has been designed for small to medium size passenger cars. The design adopts a slight deviation from the conventional method, thus resulting in broader surge margin and better efficiency at off-design region. This paper presents the design of the new compressor scroll and its performance validation. The new compressor scroll is coupled to a standard wheel and tested on the cold gas stand followed by the on-engine testing. The testing program focused on back-to-back comparison with the standard compressor scroll, as well as identifying on-engine operational regime with better brake specific fuel consumption (BSFC) and transient performance. A specially instrumented 1.6L gasoline engine was used for this study. The engine control unit configurations are kept constant for both the compressor testing. The intake and exhaust manifold has been customized to fit the turbochargers and kept identical between the standard and new compressor scroll installations. The turbocharger with new compressor scroll design is found to work at…
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Analysis of Unburned Hydrocarbon Generated from Wall Under Lean Combustion

Toyota Motor Corporation-Hiroyuki Sakai, Sei Sato, Sachio Mori, Shinichiro Nogawa, Koichiro Nakatani
  • Technical Paper
  • 2020-01-0295
To be published on 2020-04-14 by SAE International in United States
The location and cause of unburned HC is analyzed by CFD and LIEF. Under lean combustion, the surface flame quenching occurs over a wide range of walls and large amount of HC is generated. The quenching distance and HC can be organized by laminar combustion speed and boost pressure, those are related to thermal boundary layer thickness.
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Initial Investigations into the Benefits and Challenges of Eliminating Port Overlap in Wankel Rotary Engines

University of Bath-James Turner, Matthew Turner, Giovanni Vorraro, Toby Thomas
  • Technical Paper
  • 2020-01-0280
To be published on 2020-04-14 by SAE International in United States
The Wankel rotary engine has historically found limited success in part due to poor combustion efficiency and challenges around hydrocarbon emissions. This is despite its significant advantages in terms of power density, compactness, vibrationless operation, and reduced parts count in relation to the now-dominant 4-stroke reciprocating engine. A large part of the reason for the poor fuel economy and high hydrocarbon emissions of the Wankel engine is the very significant amount of overlap that the use of ports opened and closed by the rotor edges creates. This paper investigates the feasibility operating a Wankel internal combustion engine with zero port overlap in order to mitigate this effect. As discussed in the paper, arranging this condition unfortunately significantly reduces the compression and/or expansion ratio of the engine, so compounding (using turbomachinery) is applied here in order to recover any expansion energy sacrificed in configuring the engine to have no overlap. In order to conduct this investigation a baseline 1-D model was implemented and correlated to the in-production Advanced Innovative Engineering (UK) Ltd 225CS peripherally-ported single-rotor Wankel…
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Influence of the Kind of Fuel Kind in the Ignition of Diesel Dual Fuel Operation with Introduced Natural Gas Combining EGR and Supercharging

Kagoshima University-Eiji Kinoshita, Takeshi Otaka
Niigata Institute of Technology-Yasufumi Yoshimoto
  • Technical Paper
  • 2019-32-0581
Published 2020-01-24 by Society of Automotive Engineers of Japan in Japan
A number of studies in diesel dual fuel (DDF) operation which introduces natural gas from the intake pipe and ignites it by a diesel fuel injection in the combustion chamber have been conducted using conventional diesel engines. The present study investigated the influence of the ignition fuel on engine performance, combustion characteristics, and emissions with a combination of EGR and supercharging in DDF operation. The experiments employed iso-pentanol blended fuels for the ignition. Isopentanol is a next generation bio-alcohol fuel produced from cellulosic biomass, and actual use can be expected. The experiments were conducted at two CNG supply rates, 0% (ordinary diesel operation) and at a 40±4% (DDF operation) energy basis, and with EGR rates varied from 0 to 26%. The boost pressure was set at two conditions, 100 kPa (naturally aspirated, N/A) and 120 kPa (supercharged, S/C) with a supercharger. Four kinds of ignition fuels were used, JIS No.2 diesel fuel as a reference, neat methyl laurate (LME) which is a major component of coconut oil biodiesel, and two iso-pentanol blended fuels with 30%…
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Rework of an in-line two-cylinder engine for the application in Formula Student

FH JOANNEUM Graz, Department of Automotive Engineering-Michael Feigl B.Sc, Dominik Rößmann B.Sc, FH-Prof. DI Michael Trzesniowski
  • Technical Paper
  • 2019-32-0532
Published 2020-01-24 by Society of Automotive Engineers of Japan in Japan
Formula Student is an international design competition, where students all over the world develop, design and build their own race car and afterwards compete with each other at different disciplines at events worldwide. The development process includes every module of the race car and the team of joanneum racing graz has focused on the powertrain since the beginning.The following paper contains an overview of the reworking process of an in-line two-cylinder engine for the application in Formula Student. The intention was to increase the BMEP and at the same time reach a desired power/weight ratio of the engine. The process of selecting the most appropriate turbocharger by means of experimental testing on an engine dynamometer, as well as its optimization by means of numerical simulation, is outlined. Subsequently, the paper discusses the challenges regarding valve timing and finding the best trade-off between power and residual gas with the help of 1D-simulations. The necessary implementation of an intercooler and its efficiency optimization is also addressed. Finally, the calibration and optimization of the setup on the engine…
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Comparison Between MCC and MZCM Combustion Models

Pontifícia Universidade Católica de Minas Gerais-Paulo Ricardo da Penha, Rogério Jorge Amorim
  • Technical Paper
  • 2019-36-0133
Published 2020-01-13 by SAE International in United States
This paper evaluates the ability of two combustion models to predict a small HSDI diesel engine operation after changing its operational parameters. Both Multi-Zone Combustion Model (MZCM) and Mixing Controlled Combustion (MCC) are inherently coupled to the fuel injection process allowing great freedom of simulation for multistage injection engines but also requiring consistent calibration of the model parameters. In the present work, two operating conditions of a reference research engine are modelled and tuned in the AVL Boost® software using both MCC and MZCM to model the combustion process. The operational conditions evaluated are defined by changes in EGR rate, fuel injection start and distribution, boost pressure, and injection pressure. The predictive ability of each model is assessed by comparing the output results accuracy and the number of parameters changes needed to tune the model for a given change of operation. The novelty of this work resides in the comparison of the two models, as built in the software, in a practical simulation process. Both models have a similar amount of base parameters to be…
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Numerical Optimization of Compression Ratio for a PPC Engine running on Methanol

Lund University-Erik Svensson, Sebastian Verhelst
  • Technical Paper
  • 2019-01-2168
Published 2019-12-19 by SAE International in United States
Partially premixed combustion (PPC) has shown to produce high gross indicated efficiencies while yielding lower pollutant emissions, such as oxides of nitrogen and soot, than conventional diesel combustion. Gasoline fuels with a research octane number (RON) of 60-70 have been proposed as optimal for PPC as they balance the trade-off between ensuring good combustion stability at low engine loads and avoiding excessive peak pressure rise rates at high loads. However, measures have to be taken when optimizing the engine operating parameters to avoid soot emissions. In contrast, methanol has a much lower propensity for soot formation. However, due to a higher RON of methanol the required intake temperature is higher for the same engine compression ratio to ensure auto-ignition at an appropriate timing. Increasing the compression ratio allows a lower intake temperature and improves combustion stability as well as engine brake efficiency. Nevertheless, a higher compression ratio generally increases in-cylinder heat losses and peak pressure. These effects were investigated in a simulation study, which combined 0-D and 1-D models, of a multi-cylinder heavy-duty Scania D13…
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Experimental Proof-of-Concept of HiL Based Virtual Calibration for a Gasoline Engine with a Three-Way-Catalyst

FEV Europe GmbH-Pietro Gardini, Thomas Scheel, Vitali Walter, Jaykumar Kansagara Raul Tharmakulasingam, Marius Böhmer, Martin Nijs
Institute for Combustion Engines, RWTH Aachen University-Feihong Xia, Frank Dorscheidt, Stefan Lücke, Jakob Andert
  • Technical Paper
  • 2019-01-2301
Published 2019-12-19 by SAE International in United States
The increasing complexity of modern combustion engines together with the substantial variability of hybrid electric powertrains, lead to new challenges in function development, system integration and vehicle calibration processes. Hardware-in-the-Loop (HiL) simulations have been introduced to front-load part of the testing and calibration tasks from the vehicle to a virtual environment. With this approach, the simulation quality and the cost-benefit ratio are strongly dependent on the accuracy of the plant modelling and the computational effort.This paper introduces a novel HiL simulation platform for an engine control unit (ECU) with a crank-angle resolved real-time model (GT-Power) for a gasoline engine with direct fuel injection, single stage turbocharging and a three-way catalyst. By simplifying the fluid dynamics simulation model from the concept phase, a good compromise between model accuracy and computation speed can be achieved with relatively low effort. The coupling of the engine model and the hardware ECU has been implemented using a realtime workstation with a co-simulation platform (xMOD) coupled to a HiL-simulator with the necessary I/O boards (dSPACE). The closed-loop boost pressure and the…
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