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A Novel 1D Co-Simulation Framework for the Prediction of Tailpipe Emissions Under Different IC Engine Operating Conditions

Aristotle University of Thessaloniki-Grigorios Koltsakis, Zissis Samaras
EMPA-Panayotis Dimopoulos Eggenschwiler, Viola Papetti, Jakub Rojewski, Patrik Soltic
  • Technical Paper
  • 2019-24-0147
To be published on 2019-09-09 by SAE International in United States
The prediction of the pollutants emitted by internal combustion engines during driving cycles has been a challenge since the introduction of the emission regulation legislation. During the last decade, along with the more tightening limits and increased public concern about the matter of air quality, the possibility of simulating various driving tests with cost effective computing facilities has become a key feature for modern simulation codes. Many 1D simulation tools are available on the market, offering real time models capable of achieving the simulation of any driving cycle in limited time frames. These approaches are based on the extreme simplification of the engine geometry and on the adoption of engine maps, which, for any engine operating condition, give the engine output in terms of power, or torque, and of exhaust gas composition. Specific fluid dynamic models are used to track the composition along the exhaust system and, with the aid of ad-hoc modules, to evaluate the conversion efficiency of after-treatment devices, such as TWC, GPF, DPF, DOC, SCR and so on. This work is based…
 
Open Access

Monotonic and Cyclic Creep of Cast Materials for Exhaust Manifolds

SAE International Journal of Materials and Manufacturing

Royal Institute of Technology, Sweden-Christian Öberg, Stefan Jonsson
Scania, Sweden-Baohua Zhu
  • Journal Article
  • 05-12-02-0012
Published 2019-05-13 by SAE International in United States
Cast materials are creep tested between 600 and 900°C using three methods: (i) tensile testing at different strain rates, (ii) stress relaxation during thermal cycling and (iii) traditional creep tests at constant load. Comparisons are made between fast and slow methods and between monotonic and cyclic deformation modes. The tested materials, SiMo51, SiMo1000, Ni-resist D5S and HK30, are used for exhaust manifolds in heavy-duty diesel engines. The fast and cheap methods, (i) and (ii), were used on all materials, while the tedious and costly method, (iii), was used on SiMo51 only. The creep rates from monotonic tensile tests and stress relaxations during thermal cycling agree well. There is no difference between monotonic and cyclic creep rates, and cyclic rates are practically unchanged with the number of thermal cycles. No or small differences in creep rates are observed when comparing tension and compression, although three of the materials include large graphite nodules. At 700°C, a Norton plot for SiMo51 shows coinciding results for tensile test and compressive stress relaxations, whereas the minimum creep rates from constant…
 

Development of New I4 2.5L Gasoline Direct Injection Engine

Nissan Automotive Technology Co., Ltd.-Naohiro Yoshida
Published 2019-04-02 by SAE International in United States
A new 2.5L 4-cylinder direct-injection engine (PR25DD) was developed for use on the new 2019 model year Altima as a successor to the QR25DE engine mounted on the previous model. The development concept defined for this new 4-cylinder engine was to achieve acceleration, fuel economy and noise, vibration and harshness (NVH) performance at the highest possible levels by incorporating the latest technologies, including a world’s first application.The PR25DD engine continues Nissan’s new engine concept of recent years with regard to the basic engine systems, including the use of direct injection, an electrically operated valve timing control (VTC) system, cooled exhaust gas recirculation (EGR), an integrated exhaust manifold, mirror bore coating and a variable displacement oil pump [1]. In addition to these features, it also adopts a resin intake port. The resin port is inserted into the intake port cast in the cylinder head, thereby forming an air layer between the intake air passageway and the head inner wall so as to suppress the rise in intake air temperature. This world’s first application of a resin…
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Effect of Exhaust Runner Length, Valve Timing and Lift on the Performance of a Gasoline Engine

University of South Australia-Saiful Bari
Published 2019-04-02 by SAE International in United States
Internal combustion (IC) engine exhaust system can influence the engine’s performance in a significant way. This paper shows that a variable exhaust manifold runner length can improve the engine performance in terms of its output torque by over 10% especially at lower engine speed. Similarly, other exhaust systems such as valve timing and valve lift can improve the performance of the engine in different magnitudes. But when smaller improvements are clubbed together, a significant improvement can be achieved. This paper researches first the exhaust runner length on the engine’s performance. Then, the exhaust valve timing is adjusted to further improve the engine torque produced for the exhaust runner lengths analyzed. Study of a combined effect showed that the runner length requirement shifts slightly as the valve timing is changed. Due to practical limitations foreseen in having longer runner lengths and limitations in the rate of runner length variation, certain areas have to undergo through a region where the torque values are as low as they can be. Though this happens in every single exhaust system…
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Steady-State, Transient and WLTC Drive-Cycle Experimental Performance Comparison between Single-Scroll and Twin-Scroll Turbocharger Turbine

Imperial College London-Ricardo Martinez-Botas
Mitsubishi Heavy Industries Engine & Turbochargers-Motoki Ebisu
Published 2019-04-02 by SAE International in United States
The use of twin-scroll turbocharger turbine in automotive powertrain has been known for providing better transient performance over conventional single-scroll turbine. This has been accredited to the preservation of exhaust flow energy in the twin-scroll volute. In the current study, the performance comparison between a single and twin-scroll turbine has been made experimentally on a 1.5L passenger car gasoline engine. The uniqueness of the current study is that nearly identical engine hardware has been used for both the single and twin-scroll turbine volutes. This includes the intake and exhaust manifold geometry, turbocharger compressor, turbine rotor and volute scroll A/R variation trend over circumferential location. On top of that, the steady-state engine performance with both the volutes, has also been tuned to have matching brake torque. Such highly comparable setup enabled a more precise evaluation on the effect of pulse-isolation in the twin-scroll turbine volute during transient process. The steady-state performance comparison shows the amplitude of exhaust pulse in the twin-scroll volute is substantially higher than in the single-scroll volute, hence confirming the preservation of pulse…
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A 1D Real-Time Engine Manifold Gas Dynamics Model Using Orthogonal Collocation Coupled with the Method of Characteristics

University of Waterloo-Amer Keblawi, John McPhee
Published 2019-04-02 by SAE International in United States
In this paper, a new solution method is presented to study the effect of wave propagation in engine manifolds, which includes solving one-dimensional models for compressible flow of air. Velocity, pressure, and density profiles are found by solving a system of non-linear Partial Differential Equations (PDEs) in space and time derived from Euler’s equations. The 1D model includes frictional losses, area change, and heat transfer. The solution is traditionally found by utilizing the Method of Characteristics and applying finite difference solutions to the resulting system of ordinary differential equations (ODEs) over a discretized grid. In this work, orthogonal collocation is used to solve the system of ODEs that is defined along the characteristic curves. Orthogonal polynomials are utilized to approximate velocity, pressure, sound speed, and the characteristic curves along which the system of PDEs reduce to a system of ODEs. The approximation polynomials are defined over the whole manifold domain, transforming Euler’s equations into a system of ODEs that can be solved using a generic ODE solver. This reduction is done symbolically using a computer…
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Water Injection to Improve Direct Injection Spark Ignition Engine Efficiency

Groupe PSA-Faycal Souidi
IFP Energies Nouvelles-Matthieu Cordier, Matthieu Lecompte, Louis-Marie Malbec, Benjamin Reveille
Published 2019-04-02 by SAE International in United States
The increasing use of downsized turbocharged gasoline engines for passengers cars and the new European homologation cycles (WLTC and RDE) both impose an optimization of the whole engine map. More weight is given to mid and high loads, thus enhancing knock and overfueling limitations. At low and moderate engine speeds, knock mitigation is one of the main issues, generally addressed by retarding spark advance thereby penalizing the combustion efficiency. At high engine speeds, knock still occurs but is less problematic. However, in order to comply with thermo-mechanical properties of the turbine, excess fuel is injected to limit the exhaust gas temperature while maximizing engine power, even with cooled exhaust manifolds. This also implies a decrease of the combustion efficiency and an increase in pollutant emissions.Water injection is one way to overcome both limitations. With its high specific heat, water may be a solution to accurately control the temperature evolution in the cylinder. At low or medium speed, it can help to cool down the working gas and prevent knock occurrence. At high speed, water can…
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Towards Quantitative Prediction of Urea Thermo-Hydrolysis and Deposits Formation in Exhaust Selective Catalytic Reduction (SCR) Systems

Convergent Science Inc.-Shaoping Quan, Scott Drennan
IFP Energies Nouvelles-Chaouki Habchi, Julien Bohbot
Published 2019-04-02 by SAE International in United States
In order to assist in fast design cycle of Diesel engines selective catalytic reduction (SCR) exhaust systems, significant endeavor is currently being made to improve numerical simulation accuracy of urea thermo-hydrolysis. In this article, the achievements of a recently developed urea semi-detailed decomposition chemical scheme are assessed using three available databases from the literature.First, evaporation and thermo-hydrolysis of urea-water solution (UWS) single-droplets hanged on a thin thermocouple ring (127 μm) as well as on a thick quartz (275 μm), have been simulated at ambient temperature conditions ranging from 473K to 773K. It has been shown that the numerical results, in terms of evaporation rate and urea gasification, as well as droplet temperature history are very close to the experiments if the heat flux coming from the droplet support is properly accounted for. Indeed, an additional conduction flux has proved to be necessary in the evaporation model in order to account for the droplet heating coming from the support (i.e. thermocouple ring or quartz bead). This additional heat conduction flux has shown more critical for droplets…
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Simulation and Experimental Study of Intake Air Flow Pulsation and Resolution for a 2-Cylinder Uneven Firing (0°-540°) Naturally Aspirated and Turbocharged CPCB II Diesel Engine

Ashok Leyland, Ltd-Devanandh Vasudevan
Ashok Leyland, Ltd.-Saravana Venkatesh R, S Krishnan, Krishna Kumar Varathan
Published 2019-04-02 by SAE International in United States
Development of a 2-cylinder uneven firing engine from a 4-cylinder parent engine is associated with variation in air mass flow due to the combined effects of both engine downsizing as well the large firing gap between the cylinders especially 540°. This affects the turbocharger performance & durability and engine emissions due to fluctuations in the air mass flow. This paper investigates the effects of engine geometries such as stroke, valve overlap, cam profiles, intake and exhaust manifold configuration and surge tank effect through one-dimensional thermodynamic simulations and experimental tests, thus reducing the pulsation effect by 85%. Two engine configurations - naturally aspirated engine for 15 kVA power rating and turbocharged version for 30 kVA power rating were considered for the development study. The former was evaluated with different cam profiles and stroke which effected in reducing the air mass flow pulse variation by 80% and the latter by combination of different turbocharger trims and dampening tank resulting in 85% reduction.Experimental tests were carried out for all the engine configurations on an instrumented engine test bench…
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A Test Rig for Evaluating Thermal Cyclic Life and Effectiveness of Thermal Barrier Coatings inside Exhaust Manifolds

KTH Royal Institute of Technology-Ulf Olofsson
Scania CV AB-Anders Thibblin
Published 2019-04-02 by SAE International in United States
Thermal Barrier Coatings (TBCs) may be used on the inner surfaces of exhaust manifolds in heavy-duty diesel engines to improve the fuel efficiency and prolong the life of the component. The coatings need to have a long thermal cyclic life and also be able to reduce the temperature in the substrate material. A lower temperature of the substrate material reduces the oxidation rate and has a positive influence on the thermo-mechanical fatigue life. A test rig for evaluating these properties for several different coatings simultaneously in the correct environment was developed and tested for two different TBCs and one oxidation-resistant coating. Exhausts were redirected from a diesel engine and led through a series of coated pipes. These pipes were thermally cycled by alternating the temperature of the exhausts. Initial damage in the form of cracks within the top coats of the TBCs was found after cycling 150 times between 50°C and 530°C. Temperature calculations showed that, besides evaluating the thermal cyclic life, the test method has the potential to provide a quick ranking of coating…
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