Performance and Emissions of an Advanced Multi-Cylinder SI Engine Operating in Ultra-Lean Conditions

Bozza, Fabio; Tufano, Daniela; Malfi, Enrica; Teodosio, Luigi; Libert, C.; Bellis, Vincenzo De

doi:10.4271/2019-24-0075

Cited by 8 publications

(5 citation statements)

References 29 publications

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“…The regenerative braking is made by EM. This work deals with a prototype vehicle, equipped by a very efficient ICE (engine 1), under development [22], and whose features are listed in Table 2. The main feature of engine 1 is to operate in ultra-lean conditions, resulting in very high efficiencies over the entire operating domain.…”

Section: Hev Architecturementioning

confidence: 99%

Development of an Efficient Thermal Electric Skipping Strategy for the Management of a Series/Parallel Hybrid Powertrain

2021

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In recent years, the development of hybrid powertrain allowed to substantially reduce the CO2 and pollutant emissions of vehicles. The optimal management of such power units represents a challenging task since more degrees of freedom are available compared to a conventional pure-thermal engine powertrain. The a priori knowledge of the driving mission allows identifying the actual optimal control strategy at the expense of a quite relevant computational effort. This is realized by the off-line optimization strategies, such as Pontryagin minimum principle—PMP—or dynamic programming. On the other hand, for an on-vehicle application, the driving mission is unknown, and a certain performance degradation must be expected, depending on the degree of simplification and the computational burden of the adopted control strategy. This work is focused on the development of a simplified control strategy, labeled as efficient thermal electric skipping strategy—ETESS, which presents performance similar to off-line strategies, but with a much-reduced computational effort. This is based on the alternative vehicle driving by either thermal engine or electric unit (no power-split between the power units). The ETESS is tested in a “backward-facing” vehicle simulator referring to a segment C car, fitted with a hybrid series-parallel powertrain. The reliability of the method is verified along different driving cycles, sizing, and efficiency of the power unit components and assessed with conventional control strategies. The outcomes put into evidence that ETESS gives fuel consumption close to PMP strategy, with the advantage of a drastically reduced computational time. The ETESS is extended to an online implementation by introducing an adaptative factor, resulting in performance similar to the well-assessed equivalent consumption minimization strategy, preserving the computational effort.

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Section: Hev Architecturementioning

confidence: 99%

Development of an Efficient Thermal Electric Skipping Strategy for the Management of a Series/Parallel Hybrid Powertrain

2021

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“…The logical scheme of the optimization process was already reported in a previous author's work [36], and here it is partially modified by the addition of SML/EML and EVC (exhaust valve closure) variables. The optimizer algorithm, at each step with an iterative process, selects the eight engine control variables, passing them to the 1D engine model to evaluate the variables of interest.…”

Section: Optimization Approach For Engine Calibrationmentioning

confidence: 99%

Optimal Calibration Strategy of a Hybrid Electric Vehicle Equipped with an Ultra-Lean Pre-Chamber SI Engine for the Minimization of CO2 and Pollutant Emissions

et al. 2020

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The complexity of modern hybrid powertrains poses new challenges for the optimal control concerning, on one hand, the thermal engine to maximize its efficiency, and, on the other hand, the vehicle to minimize the noxious emissions and CO2. In this context, the engine calibration has to be conducted by considering simultaneously the powertrain management, the vehicle characteristics, and the driving mission. In this work, a calibration methodology for a two-stage boosted ultra-lean pre-chamber spark ignition (SI) engine is proposed, aiming at minimizing its CO2 and pollutant emissions. The engine features a flexible variable valve timing (VVT) control of the valves and an E-compressor, coupled in series to a turbocharger, to guarantee an adequate boost level needed for ultra-lean operation. The engine is simulated in a refined 1D model. A simplified methodology, based on a network of proportional integral derivative (PID) controllers, is presented for the calibration over the whole operating domain. Two calibration variants are proposed and compared, characterized by different fuel and electric consumptions: the first one aims to exclusively maximize the brake thermal efficiency, and the second one additionally considers the electric energy absorbed by the E-compressor and drained from the battery. After a verification against the outcomes of an automatic optimizer, the calibration strategies are assessed based on pollutant and CO2 emissions along representative driving cycles by vehicle simulations. The results highlight slightly lower CO2 emissions with the calibration approach that minimizes the E-compressor consumption, thus revealing the importance of considering the engine calibration phase, the powertrain management, the vehicle characteristics, and its mission.

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“…Regarding the heat transfer modeling, a modified Hohenberg-like correlation is adopted, while the piston, cylinder liner and head temperatures are computed by the finite element approach, implemented into the 1D code. NO and CO emissions are computed through the implementation of 'users' sub-models in the 1D code [13,22]. In particular, CO concentrations are estimated by solving a simple chemical kinetic sub-model [23], while for NO concentration the semi-detailed chemical kinetic scheme proposed by Andrae [24] is solved in the burned gas zone.…”

Section: Engine Description Modeling and Validationmentioning

confidence: 99%

“…Common technical solutions for SI ICEs include the downsizing coupled to turbocharging [2], innovative valve strategies [3], increased or variable compression ratio (CR) [4,5,6], external cooled exhaust gas recirculation (EGR) [7,8], water injection [9,10], employment of alternative fuels [11,12], and pre-chamber ignition devices [13]. These solutions allow some benefits in the engine performance but they highly depend on the investigated operating conditions [14,15].…”

Section: Introductionmentioning

confidence: 99%

1D numerical study on hydrogen injection enabling ultra-lean combustion in a small gasoline Spark Ignition engine

Teodosio

Pirrello²,

Marchitto

2020

E3S Web Conf.

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This paper deals with the effects of hydrogen port injection on combustion evolution, efficiency and exhaust emissions of a small turbocharged gasoline Spark-Ignition engine through a 1D numerical code. First, the experiments on the base engine architecture are performed at different speeds and at low/medium loads. The experimental findings are used to validate a 1D model of the whole engine, developed within a commercial code. 1D model is also refined with “user-defined” sub-models for an accurate description of the in-cylinder phenomena, namely turbulence, combustion, heat transfer, and emissions. In a second step, 1D model is virtually modified through the installation of an hydrogen injector in each intake runner, while the combustion sub-model also accounts for the impact of hydrogen addition on the laminar flame speed through a dedicated correlation. 1D simulations are performed at low/medium loads and fixed speed of 2250 rpm with 5% of hydrogen by volume in the intake air. Numerical investigations show that hydrogen addition to gasoline/air mixtures allows relevant efficiency benefits (up to a maximum percent gain of 19%), while the NO emissions are almost eliminated. Consequently, hydrogen-boosted combustion represents a potential solution to achieve very high efficiency and reduced pollutant emissions of gasoline spark ignition engines equipped with a conventional combustion system.

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Performance and Emissions of an Advanced Multi-Cylinder SI Engine Operating in Ultra-Lean Conditions

Cited by 8 publications

References 29 publications

Development of an Efficient Thermal Electric Skipping Strategy for the Management of a Series/Parallel Hybrid Powertrain

Development of an Efficient Thermal Electric Skipping Strategy for the Management of a Series/Parallel Hybrid Powertrain

Optimal Calibration Strategy of a Hybrid Electric Vehicle Equipped with an Ultra-Lean Pre-Chamber SI Engine for the Minimization of CO2 and Pollutant Emissions

1D numerical study on hydrogen injection enabling ultra-lean combustion in a small gasoline Spark Ignition engine

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