THIP: A new TPRF-like fuel surrogate development approach to better match real fuel properties

Nowadays, numerical simulations play an important role during the design and optimization phase of the after-treatment system (ATS). Simulation tools, based on both simple 1D or detailed CFD approa...

Calibration of the Oxygen Storage Reactions for the Modeling of an Automotive Three-Way Catalyst

This work is focused on the development and validation of a spark advance controller, based on a piston “damage” model and a predictive knock model. The algorithm represents an integrated and innovative way to manage both the knock intensity and combustion phase. It is characterized by a model-based open-loop algorithm with the capability of calculating with high accuracy the spark timing that achieves the desired piston damage in a certain period, for knock-limited engine operating conditions. Otherwise, it targets the maximum efficiency combustion phase. Such controller is primarily thought to be utilized under conditions in which feedback is not needed. In this paper, the main models and the structure of the open-loop controller are described and validated. The controller is implemented in a rapid control prototyping device and validated reproducing real driving maneuvers at the engine test bench. Results of the online validation process are presented at the end of the paper.

Development and Experimental Validation of an Adaptive, Piston-Damage-Based Combustion Control System for SI Engines: Part 1—Evaluating Open-Loop Chain Performance

Experimental and kinetic study on the pyrolysis and oxidation of isopentane in a jet-stirred reactor

Simple surrogate formulations for gasoline are useful for modelling purposes and for comparing experimental results using a carefully designed fuel. Simple three-component surrogates based on primary reference fuels (PRF) and Toluene (TPRF) are frequently used to match the antiknock properties of actual gasoline fuels through the RON and MON. However, using PRF or TPRFs to test or to calibrate gasoline engines is still challenging, with the main difficulty being the capabilities of PRF fuels to match the physical properties of the road fuel such density, volatility (DVPE) and the distillation curve. To overcome such issues, an alternative to TPRF is presented in this work with a focus on premium fuel (RON98 EN228). This alternative consists of replacing some or all of isooctane by isopentane. In the event of total replacement, a three-component “THIP” (Toluene, Heptane, IsoPentane) surrogate fuel is produced. The physical and combustion properties of isopentane makes it easier to create surrogates that can match the DVPE, RON, MON and distillation characteristics of a real fuel. Furthermore, the use of isopentane allows the definition of a wider range of surrogate fuel compositions that can replicate the RON and MON of a given fuel. Surrogate formulations were developed at Shell Global Solutions that matched the RON, MON and selected physical properties of a reference premium gasoline (RPG). A Rapid Compression Machine (RCM) in PCFC was used to demonstrate that those surrogates can reproduce the essential autoignition characteristics of the selected RPG. Two mechanisms were used to predict RCM data and showed reasonable agreement, opening some perspective for further investigations. Finally, an engine test performed at Ferrari test facilities demonstrated that simple surrogates containing isopentane can be used to closely match the knock-limited combustion phasing of an RPG. In this paper, it is demonstrated such surrogates have advantages compared to TPRFs in being able to match the properties of a real fuel and that the surrogate approach is consistent with RCM data and engine results.

Evaluating a novel gasoline surrogate containing isopentane using a rapid compression machine and an engine

Development and Validation of a Control-Oriented Analytic Engine Simulator

This work focuses on the implementation of innovative adaptive strategies and a closed-loop chain in a piston-damage-based combustion controller. In the previous paper (Part 1), implemented models and the open loop algorithm are described and validated by reproducing some vehicle maneuvers at the engine test cell. Such controller is further improved by implementing self-learning algorithms based on the analytical formulations of knock and the combustion model, to update the fuel Research Octane Number (RON) and the relationship between the combustion phase and the spark timing in real-time. These strategies are based on the availability of an on-board indicating system for the estimation of both the knock intensity and the combustion phase index. The equations used to develop the adaptive strategies are described in detail. A closed-loop chain is then added, and the complete controller is finally implemented in a Rapid Control Prototyping (RCP) device. The controller is validated with specific tests defined to verify the robustness and the accuracy of the adaptive strategies. Results of the online validation process are presented in the last part of the paper and the accuracy of the complete controller is finally demonstrated. Indeed, error between the cyclic and the target combustion phase index is within the range ±0.5 Crank Angle degrees (°CA), while the error between the measured and the calculated maximum in-cylinder pressure is included in the range ±5 bar, even when fuel RON or spark advance map is changing.

Development and Experimental Validation of an Adaptive, Piston-Damage-Based Combustion Control System for SI Engines: Part 2—Implementation of Adaptive Strategies

This paper presents the modeling of the transient phase of catalyst heating on a high-performance turbocharged spark ignition engine with the aim to accurately predict the exhaust thermal energy available at the catalyst inlet and to provide a "virtual test rig" to assess different design and calibration options.The entire transient phase, starting from the engine cranking until the catalyst warm-up is completed, was taken into account in the simulation, and the model was validated using a wide data-set of experimental tests.The first step of the modeling activity was the combustion analysis during the transient phase: the burn rate was evaluated on the basis of experimental in-cylinder pressure data, considering both cycle-to-cycle and cylinder-to-cylinder variations.Then, as far as the exhaust temperatures are concerned, a detailed model of the thermocouples was implemented to replicate the physical behavior of the sensors during the warm-up and to compare the simulated temperatures with the measured ones.Finally, a complete analysis of the energy balance during the transient was carried out: the thermal power available to the catalyst inlet was obtained from a complete analysis of power losses (i.e. friction and pumping losses, in-cylinder heat transfer, engine block and engine coolant heating, exhaust manifold heat transfer, etc.).In conclusion, the proposed methodology allows to reliably simulate in details the Cat-Heating transient, showing a valuable potential in driving the main design and calibration choices during the engine development process.

Matteo Cucchi

Papers

Evaluating a novel gasoline surrogate containing isopentane using a rapid compression machine and an engine

Development and Experimental Validation of an Adaptive, Piston-Damage-Based Combustion Control System for SI Engines: Part 1—Evaluating Open-Loop Chain Performance

Development and Validation of a Control-Oriented Analytic Engine Simulator

Development and Experimental Validation of an Adaptive, Piston-Damage-Based Combustion Control System for SI Engines: Part 2—Implementation of Adaptive Strategies

A Methodology for Modeling the Cat-Heating Transient Phase in a Turbocharged Direct Injection Spark Ignition Engine