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Electrification of transport, together with the decarbonization of energy production are suggested by the European Union for the future quality of air. However, in the medium period, propulsion systems will continue to dominate urban mobility, making mandatory the retrofitting of thermal engines by applying combustion modes able to reduce NOx and PM emissions while maintaining engine performances. Low Temperature Combustion (LTC) is an attractive process to meet this target. This mode relies on premixed mixture and fuel lean in-cylinder charge whatever the fuel type: from conventional through alternative fuels with a minimum carbon footprint. This combustion mode has been subject of numerous modelling approaches in the engine research community. This study provides a theoretical comparative analysis between multi-zone (MZ) and Transported probability density function (TPDF) models applied to LTC combustion process.

In order to reduce fuel consumption and polluting emissions from engines, alternative fuels such as hydrogen could play an important role towards carbon neutrality. Moreover, dual-fuel (DF) technology has the potential to offer significant improvements in carbon dioxide emissions for transportation and energy sectors. The dual fuel concept (natural gas/diesel or hydrogen/diesel) represents a possible solution to reduce emissions from diesel engines by using low-carbon or carbon-free gaseous fuels as an alternative fuel. Moreover, DF combustion is a possible retrofit solution to current diesel engines by installing a PFI injector in the intake manifold while diesel is injected directly into the cylinder to ignite the premixed mixture. In the present study, dual fuel operation has been investigated in a single cylinder research engine.

Transported probability density function (PDF) methods are currently being pursued as a viable approach to model the effects of turbulent mixing and mixture stratification, especially for new alternative combustion modes as for example Homogeneous Charge Compression ignition (HCCI) which is one of the advanced low temperature combustion (LTC) concepts. Recently, they have been applied to simple engine configurations to demonstrate the importance of accurate accounting for turbulence/chemistry interactions. PDF methods can explicitly account for the turbulent fluctuations in species composition and temperature relative to mean value. The choice of the mixing model is an important aspect of PDF approach. Different mixing models can be found in the literature, the most popular is the IEM model (Interaction by Exchange with the Mean). This model is very similar to the LMSE model (Linear Mean Square Estimation).

Ignition delay time is key to any hydrocarbon combustion process. In that sense, this parameter has to be known accurately, and especially for internal combustion engine applications. Combustion timing is one of the most important factors influencing overall engine performances like power output, combustion efficiency, emissions, in-cylinder peak pressure, etc. In the case of low temperature combustion (LTC) mode (e.g. HCCI mode), this parameter is controlled by chemical kinetics. In this paper, an ignition delay time model including 7 direct reactions and 13 species coupled with a temperature criterion is described. This mechanism has been obtained from the previous 26-step n-heptane reduced mechanism, focusing on the low temperature region which is the most important phase during the two stage combustion process. The complete model works with 7 reactions until the critical temperature is reached, leading to the detection of the ignition delay time value.

Mainly due to environmental regulation, future Engine Control Unit (ECU) will be equipped with in-cylinder pressure sensors. The introduction of this innovative solution has increased the number of involved variables, requiring an unceasing improvement in the modeling approaches and in the computational capabilities of Engine Control Unit (ECU). Hardware in the Loop (HIL) test system therefore has to provide in-cylinder pressure in real time from an adequate model. This paper describes a synthesis of our study targeted to the development of in-cylinder crank angle combustion model excluding look up tables, dedicated to HIL test bench. The main objective of the present paper is a comprehensive analysis of a reduced combustion model, applied to a direct injection Diesel engine at varying engine operating range, including single injection and multi injection strategies.

This paper presents a DI diesel engine combustion model based on double Wiebe equations approach. The aim of this work is to build a combustion model suitable for Hardware-in-the-Loop (HiL) simulations, and thus to be able to run in real-time applications. First, an ignition model is presented and correlated function of engine operating conditions. Then the combustion model parameters have been calibrated with a curve fitting technique with test bench experimental results. The calibration and validation process have been realized first on Matlab. Then the combustion model was coded in S-functions Simulink blocks suitable for HiL implementation. Offline test results for single injection cases with high engine speed (≻4000 rpm) are presented in this paper.

In an industrial context, close to the start of production and development of Engine Control Unit (ECU) systems, it is necessary to validate the complete dataset of the application and thus, to run software tests on a real ECU which is connected to a closed loop HIL Test bench, In the field of application for the simulation of dataset and the reduction of real vehicle tests, it is required to simulate an engine behaviour in terms of mixture mass and energy flow rate, temperature and pressure. The aim of this work is to reproduce this engine behaviour with a focus on combustion process and component simulation models, Oxidation Catalyst (OxiCat) and Diesel Particulate Filter (DPF). A model has been developed with the help of experimental data extracted from an Original Equipment Manufacturer (OEM) engine project.

Homogeneous Charge Compression Ignition (HCCI) combustion process is controlled by chemical kinetics which are dependent on the engine operating conditions. To reduce the number of tests needed for calibration, a computationally efficient model is needed for the entire engine operating range. The goal of this study is to provide the car manufacturers with a simple physical HCCI combustion model to assist engine tuning and engine management system optimization. The proposed model without chemical kinetics is reduced to two state variables: the temperature and the mass fraction of burning fuel. The model is driven by two functions γLT(T) and γHT(T) modeling respectively the dynamic of the first stage oxidation and the rapid transition to the main ignition. Different parameters are introduced and calibrated function of engine inlet conditions. The results are compared with a model with included chemistry and discussed.

The homogeneous charge compression ignition (HCCI) is one of the alternative to reduce significantly engine emissions for the future regulations. The combustion process in HCCI engines does not involve flame propagation or flame diffusion as in conventional internal combustion engines. Many studies have confirmed that during this mode the combustion process is mainly controlled by chemical kinetics. However, a coupled CFD and detailed chemistry simulation requires substantial memory and CPU time which may be very difficult with current computer capabilities. Thus a reduced mechanism is required to simulate the engine cycle during this operating mode to achieve more accurate analysis. In this study reduced chemistry was used with an engine CFD code combustion (Star-CD/Kinetics) to study combustion process in homogeneous charge compression ignition (HCCI) engines.