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Training / Education

FEA Beyond Basics Thermal Analysis

2019-12-16
Finite Element Analysis (FEA) is a powerful and well recognized tool used in the analysis of heat transfer problems. However, FEA can only analyze solid bodies and, by necessity thermal analysis with FEA is limited to conductive heat transfer. The other two types of heat transfer: convection and radiation must by approximated by boundary conditions. Modeling all three mechanisms of heat transfer without arbitrary assumption requires a combined use of FEA and Computational Fluid Dynamics (CFD).
Training / Education

Introduction to Power Electronics in Automotive Applications

2019-11-04
Modern power electronics (PE) devices and circuits are now in widespread use in automotive and non-automotive applications. The purpose of this course is to give an overall introduction to the key aspects of power electronic circuits, components and design in automotive applications. Topics covered include power semiconductor devices, their characteristics and operation, and their use in power electronics circuits.
Technical Paper

A Review of Spark-Assisted Compression Ignition (SACI) Research in the Context of Realizing a Production SACI Strategy

2019-08-15
2019-24-0027
Low temperature combustion (LTC) strategies have been a keen interest in the automotive industry for over four decades since they offer improved fuel efficiency compared to conventional spark-ignition (SI) engines. LTC strategies use high dilution to keep combustion temperatures below about 2000 K to reduce heat transfer losses while avoiding locally rich in-cylinder regions that produce high soot. High dilution also enables an efficiency improvement from reduced pumping work and improved thermodynamic properties, though it requires high ignition energy. Combustion can be achieved by triggering autoignition from compression energy. High compression ratios are typically required to produce this level of ignition energy, which further improves fuel efficiency. The timing of the autoignition event is influenced by fuel properties and mixture composition, and is exponentially sensitive to temperature.
Technical Paper

Dynamic and Thermal Behavior of a GDI Spray Impacting on a Heated Foil by Time-resolved Thermography

2019-08-15
2019-24-0036
The regulations about pollutant emissions imposed by Community’s laws encourage the investigation on the optimization of the combustion in modern engines and in particular in those adopting the Gasoline Direct Injection (GDI) configuration. It is known that the piston head and cylinder surface temperatures, coupled with the fuel injection pressure, strongly influence the interaction between droplets of injected fluid and the impinged wall. In the present study, the Infrared (IR) thermography is applied to investigate the thermal footprint of an iso-octane spray generated by a multi-hole GDI injector impinging on a heated thin foil. The experimental apparatus includes an invar foil (50 μm in thickness), clamped within a rigid frame heated at a fixed temperature (373 K) by Joule effect, and the GDI injector located 11 mm over the surface.
Technical Paper

A new take on porous medium approach for modelling monoliths and other multiple channel devices

2019-08-15
2019-24-0049
Porous medium approach is widely used in modelling high resistance devices such as heat exchangers, automotive catalysts or filters, where details of flow distribution inside the channels are not important. This reduces the computational time considerably, as the whole length of the monolith does not need to be modelled, and the thin boundary layers in each channel do not need to be resolved. The drawback of the approach is compromised accuracy of the flow predictions downstream of the monolith, because the mixing of the individual jets coming out of the monolith channels is not accounted for. Very few studies exist where this issue has been addressed. The methods include artificial turbulence generation, inferring turbulence information from upstream, or using hybrid modelling approach to separate the flow into channels.
Technical Paper

Study of Friction Optimization Potential for Lubrication Circuits of Light-duty Diesel Engines

2019-08-15
2019-24-0056
Over the last two decades, engine research has been mainly focused on reducing fuel consumption in view of compliance with stringent homologation targets and customer expectations. As it is well known, the objective of overall engine efficiency optimization can be achieved only through the improvement of each element of the efficiency chain, of which mechanical constitutes one of the two key pillars (together with thermodynamics). In this framework, the friction reduction for each mechanical subsystems has been one of the most important topics of modern diesel engine development. In particular, the present paper analyzes the lubrication circuit potential as contributor to the mechanical efficiency improvement, by investigating the synergistic impact of oil circuit design, oil viscosity characteristics (including new ultra-low formulations) and thermal management. For this purpose, a combination of theoretical and experimental tools were used.
Technical Paper

Oxy-fuel combustion on CFR engine operated under HCCI conditions with carbon dioxide as a thermal buffer

2019-08-15
2019-24-0119
A basic formula inspired by the Otto engine cycle shows that the thermodynamic efficiency of the engine increases as the mixture specific heat ratio and compression ratio increase. Homogenous charge compression ignition (HCCI) engines allow the combustion of a lean mixture at relatively higher compression ratios increasing the thermodynamic efficiency. At the same time, it is also a low temperature combustion and this means lower NOx emissions. One way to increase the thermodynamic efficiency of the engine is to increase the specific heat ratio by replacing the nitrogen in the oxidizer by a monoatomic gas that has the highest possible specific heat ratio. However, higher specific heat ratio results in elevated cylinder temperature and pressure leading to engine knock. The compression ratio is thus decreased to avoid this phenomenon. Also, elevated engine temperature will oxidize any nitrogen (no matter how small) forming undesired NOx emissions.
Technical Paper

Experimental investigation on the use of Argon to improve FMEP determination through motoring method

2019-08-15
2019-24-0141
Mechanical friction is still one of the current topics in internal combustion engine research and development. In the ever increasing challenge of developing more efficient and less polluting engines, friction reduction is of significant importance; whose investigation needs an accurate and reliable measurement technique. The Pressurized Motoring method is one of the techniques used for both friction and heat transfer measurements in internal combustion engines. This method is able to simulate mechanical loading on the engine components similar to the fired conditions. It also allows measurement of friction mean effective pressure (FMEP) with a much smaller uncertainty as opposed to that achieved from a typical firing setup. Despite its advantages, this method of FMEP determination is usually criticized over the fact that the thermal conditions imposed in pressurized motoring are far detached from those seen in fired conditions, hence not able to simulate the complete effects on FMEP.
Technical Paper

A novel 1D co-simulation framework for the prediction of tailpipe emissions under different IC engine operating conditions.

2019-08-15
2019-24-0147
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.
Technical Paper

Strive for Zero Emission Impact from Hybrid Vehicles

2019-08-15
2019-24-0146
Since several decades, passenger cars and light duty vehicles (LDV) reach full pollutant conversion during warm up conditions; the major challenge has been represented by the cold start and warming up strategies. The focus on technology developments of exhaust after treatment systems have been done in the thermal management in order to reach the warm up conditions as soon as possible. A new challenge is now represented by the Real Driving Emission Regulation as this bring more various, and not any longer cycle defined, Cold Start Conditions. On the other hand, once the full conversion has been reached, it would be beneficial for many EATS components if the exhaust gas temperature could be lowered. To take significant further emission steps, approaching e.g. zero emission concepts, we investigate to bring in electrical heating catalyst (EHC) and emission trap approaches. The clear goal is to have the right temperature in the right place at the right time.
Technical Paper

Heat Transfer characterization of Catalytic Converter Substrates during Warm-up

2019-08-15
2019-24-0163
The transient heat transfer behavior of a real size automotive catalytic reactor has been simulated with OpenFOAM in 1D. The model takes into consideration the gas-solid convective heat transfer, axial wall conduction and heat capacity effects in the solid phase, but also the chemical reactions of CO and C3H6 oxidations, based on simplified Arrhenius and Langmuir-Hinshelwood approaches. The associated parameters have been chosen based on the tuning of experimental data. The impact of different initial catalytic converter temperatures, inlet flow temperatures and inlet flow rates have been quantified, even in terms of overall cumulative emissions. . A dimensional analysis is proposed and dimensionless temperature difference and space-time coordinate are defined. Using this suitably modified coordinates, for the case of negligible axial solid conduction, computed solid temperature at the reactor outlet lay on the typical S-curve.
Technical Paper

Possibilities of wall heat transfer measurements at a supercharged Euro IV heavy-duty Diesel engine with high EGR-rates, an in-cylinder peak pressure of 250 bar and injection pressure up to 2500 bar

2019-08-15
2019-24-0171
A raise of efficiency is, especially for CV, the strongest selling point concerning the TCO. Accompanied by legislations, with contradictive development demands, satisfying solutions have to be found. The analysis of energy losses in modern engines shows three influencing parameters. The losses resulting from taking real gas properties and non-ideal combustion into account have only a limited potential for gains, wall heat losses are currently believed to have the highest optimization potential. Critical for the occurrence of these losses is the wall heat transfer, which can be described by coefficients. To reduce WHT accompanying losses a decrease of energy transfer between combustion gas and combustion chamber wall is necessary. A measurement of heat fluxes is needed to determine the WHT relations at the combustion chamber of an engine. Methods to reduce the WHT can be developed and their effectiveness can be evaluated.
Technical Paper

Oil Cooler Removal from Light duty Diesel Engines for Cost Reduction purpose.

2019-08-15
2019-24-0175
Automotive industry is going through phase where Energy efficiency and Cost is major differentiator in market. Taking up these considerations, development has been taken to improve thermal management of engine while optimizing the cost of engine. One of the important area in thermal management of Engine is Engine Lubrication system. This consist of Engine oil and oil cooler, which play vital role in thermal management as well as optimization of frictional losses by ensuring proper lubrication and cooling of engine components. For better thermal management of engine, a lubrication system is designed without Oil cooler, proto type made and tested. This paper deals with evaluation of various engine performance parameter & Thermal management with respect to modification carried out. Further solution of Oil cooler removal is validated at vehicle level to understand real world behaviour of the system. Finally test results were compared for further optimization in lubrication system.
Technical Paper

Performance and emissions of an advanced multi-cylinder SI engine operating in ultra-lean conditions

2019-08-15
2019-24-0075
Along the design process of a new engine, the calibration phase at the test bench usually involves a relevant percentage of the overall time-to-market. Each control variable, in fact, needs to be properly selected to optimize the performance and emissions, complying with thermal and mechanical stresses limits of the engine. This issue is still more critical for advanced engine architectures, which include additional control variables, such as valve phasing, turbocharger control, EGR level, etc. The aim of this work is the development of a numerically performed calibration procedure, applied to a prototype multi-cylinder Spark Ignition (SI) engine, designed to operate at very lean mixtures. To this aim, an active Pre-Chamber ignition system is considered. The required air flow rate is indeed provided by a Low-Pressure (LP) variable geometry turbocharger group, coupled to a high-pressure e-compressor.
Technical Paper

Description and Application Exercises of an Integrated Complete Engine Performance and Thermal model

2019-08-15
2019-24-0077
In the pursuit of more efficient high performance ICE the interactions between the gas-exchange, the combustion process and the engine thermal behavior becomes increasingly important. This is particularly challenging when aiming simultaneously for high specific power, requiring high cooling effects, and low fuel consumption, requiring appropriate management of the limited heat available at engine part loads. Furthermore, engine ordinary use, in both conventional and hybrid implementations, includes warm-up processes which affect both fuel consumption and emissions and therefore need to be accounted for. In this work a complete detailed engine performance model is integrated with a complete engine thermal model. The integration process and the resulting model are studied in detail. Firstly, the interaction between the models is evaluated by comparing the difference between the results of the models run as standalone with the ones of the integrated model.
Technical Paper

An embedded simulation approach for tolerance analysis on vehicle propulsion subsystem

2019-08-15
2019-24-0079
An increasing demand for reducing cost and time effort of the design process via improved CAE (Computer-Aided Engineer) tools and methods has characterized the automotive industry over the past two decades. One of the main challenge regarded the effective simulation of a vehicle’s propulsion system dealing with different physical domains: several examples have been proposed in literature mainly based on co-simulation approach which involves a specific tool for each propulsion system part modeling. Nevertheless, these solutions are not fully suitable and effective to perform statistical analysis including all physical parameters. In this respect, this paper presents the definition and implementation of a new simulation methodology applied to a propulsion subsystem.
Technical Paper

Validation of heat losses prediction using Conjugate Heat Transfer simulation for an internal combustion engine

2019-08-15
2019-24-0091
New technologies are required to improve engine thermal efficiency. For this it is necessary to use all the tools available nowadays, in particular computational tools, which allow testing the viability of different solutions at reduced cost. In addition, numerical simulations often provide more complete and precise information than experimental tests. Such is the case for the study of the heat transfer through the walls of an engine. Conjugate Heat Transfer (CHT) simulations permit precise calculations of the heat transfer rate from gas to walls throughout the whole engine cycle, and thus it is possible to know such details as the instantaneous heat losses and wall temperature distribution on the walls, which no experiment can give. Nevertheless, it is important to validate CHT calculations, either with some experimental measurements or with some other reliable tool, such as 0D-1D modelling known to work well.
Technical Paper

Development and validation of SI combustion models for natural-gas heavy-duty engines

2019-08-15
2019-24-0096
Flexible, reliable and consistent combustion models are necessary for the improvement of the next generation spark-ignition engines. Different approaches have been proposed and widely applied in the past. However, the complexity of the process involving ignition, laminar flame propagation and transition to turbulent combustion need further investigations. Purpose of this paper is to compare two different approaches describing turbulent flame propagation. The first approach is the one-equation flame wrinkling model by Weller, while the second is the Coherent Flamelet Model (CFM). Ignition is described by a simplified deposition model while the correlation from Herweg and Maly is used for the transition from the laminar to turbulent flame propagation. Validation of the proposed models was performed with experimental data of a natural-gas, heavy duty engine running at different operating conditions.
Technical Paper

The Impact of the Temperature-Regulated Semitransparent Heat Insulation of a Combustion Chamber on Working Processes of a Diesel Engine

2019-08-15
2019-24-0176
The paper is about the physico-mathematical model describing the heat parameters of the gas atmosphere in the diesel engine cylinder during the whole working cycle taking into consideration the features of radiant heat exchange inside semitransparent ceramic thermal barrier coatings (TBCs) of the combustion chamber. The simulation of convective and radiant heat transfer was based on analysis of changing of interconnected heat parameters for hot gas of combustion chamber and its heat insulation depending on the crank angle. Thermal radiation within the IR wavelength range of a flame, gas, and soot particles in a cylinder was modelled as a radiant component of the total heat flux. The temperature regime of ceramic insulation (with a transparency band up to ~3-4 μm) was significantly determined by exposure of penetrating radiation flux (with value more MW/m2) of red-hot soot particles in the spectrum of ~1-2 μm.
Technical Paper

Impact of Oil cooler on performance of Engine thermal management system

2019-08-15
2019-24-0178
Currently automotive design is facing multi facet challenges such as reduction in greenhouse gases, better thermal management, low cost solution to market, etc. Considering these challenges, effort has been taken to improve thermal management of engine while optimizing the cost of engine. This paper evaluate the impact of Oil cooler on Engine thermal behavior. To achieve this goal, Engine prototypes made with and without Oil cooler configuration. Further, engine performance and engine temperature behavior investigated with respect to with and without oil cooler configuration. Finally both configuration were validated at engine test bed and Vehicle level to understand real world behaviour of the system. Test results were compared for further optimization proposed in lubrication system.
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