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Technical Paper

Sizing and Optimization of a Vortex Tube for Electric Vehicle HVAC Purposes

2021-09-05
2021-24-0099
In the recent past, an always increasing attention have been addressed to the definition and optimization of the HVAC system for fully electric vehicles. The new vehicle layouts and the different operating temperatures of the whole powertrain ask for a re-thinking of the HVAC concept for the modern architectures. In this ballpark, the possibility to deal with a compact and efficient apparatus without moving parts and capable to provide both cold and hot fluxes is really attractive. This is the reason why this work deals with the design and optimization of a vortex tube for automotive applications. Such a component, in fact, is capable to separate a highly swirled flow in two different branches, a cold one and a hot one (one inlet - two outlets). The balance in between the two obtained mass flows can be simply realized via ruling the backpressure at the hot side, with keeping constant the cold one.
Technical Paper

Optimal Energy Management Strategy for Energy Efficiency Improvement and Pollutant Emissions Mitigation in a Range-Extender Electric Vehicle

2021-09-05
2021-24-0103
The definition of the energy management strategy for a hybrid electric vehicle is a key element to ensure maximum energy efficiency. The ability to optimally manage the on-board energy sources, i.e., fuel and electricity, greatly affects the final energy consumption of hybrid powertrains. In the case of plug-in series-hybrid architectures, such as Range-Extender Electric Vehicles (REEVs), fuel efficiency optimization alone can result in a stressful operation of the range-extender engine with an excessively high number of start/stops. Nonetheless, reducing the number of start/stops can lead to long periods in which the engine is off, resulting in the after-treatment system temperature to drop and higher emissions to be produced at the next engine start.
Technical Paper

Oxidative Reactivity of Soot Particles Generated from the Combustion of Conventional Diesel, HVO and OME Collected in Particle Filter Structures

2021-09-05
2021-24-0085
The reduction of CO2 emissions in transport and power generation is currently a key challenge. One particular opportunity of CO2 reduction is the introduction of low CO2 or even CO2 neutral fuels. The combustion characteristics of such fuels are different and require engine settings modification. In addition, emissions characteristics differ significantly among different fuels. In the present study a one cylinder diesel engine was operated with conventional diesel, hydrogenated vegetable oil (HVO) and polyoxymethyl dimethyl ether (OME) as well as a series of blends. Particle filter segments were positioned in the exhaust of the engine and loaded with particles originating from the combustion of these fuels. The filter segments have been regenerated individually in a specifically designed and developed controlled temperature soot oxidation apparatus.
Technical Paper

Modeling Study of the Battery Pack for the Electric Conversion of a Commercial Vehicle

2021-09-05
2021-24-0112
Many aspects of battery electric vehicles are very challenging from the engineering point of view in terms of safety, weight, range, and drivability. Commercial vehicle engines are often subjected to high loads even at low speeds and this can lead to an intense increment of the battery pack temperature and stress of the cooling system. For these reasons the optimal design of the battery pack and the relative cooling system is essential. The present study deals with the challenge of designing a battery pack that satisfies both the conditions of lowest weight and efficient temperature control. The trade-off between the battery pack size and the electrical stress on the cells is considered. The electric system has the aim to substitute a 3.0 liters compression ignition engine mainly for commercial vehicles.
Technical Paper

Numerical Study of Thermal Management of Lithium-Ion Battery Pack Using Liquid Cooling

2021-09-15
2021-28-0118
This paper deals with the thermal management of battery cells with liquid cooling to maintain equal temperature among all the cells in the battery pack. This study starts with thermal analysis of a single battery cell with numerical analysis and validates its results with experimental analysis. By using the symmetry condition of the battery pack, six cells in a row with an aluminum block kept between two cells are considered. The two faces of the aluminum block were kept in contact with cells in the shape of an arc which is the same as the arc of a cell in order to get more heat transfer area. These aluminum blocks are penetrated by five circular channels in order to flow coolant and hinged with the channel. Numerical simulation has performed in Ansys Fluent software to get temperature distribution graphs of all six cells to find the maximum temperature of cells.
Technical Paper

CFD Analysis of a Prismatic Liquid Cooled Battery Pack to Optimize and Evaluate Pack Performance Under Variable Operating and Coolant Conditions

2021-09-15
2021-28-0116
Heat generation from Lithium-ion batteries depends on its charge/discharge rates, SoC and temperature and hence varies considerably with vehicle driving conditions, DoD, ambient operating conditions and charging rate. To design and optimize the performance of a battery cooling system, it is desirable to study the steady and transient response of the system under variable operating and heat load conditions. In the present study, 3D CFD analysis has been performed to evaluate the performance of a prismatic liquid cooled Lithium Iron Phosphate battery pack under variable flow rate, inlet temperature and heat load conditions corresponding to different SoC and charge/discharge rates. An initial study is performed to validate the CFD model with experimental data and then the model is used to optimize the shape and size of the cold plate micro channels for improved heat transfer and reduced pressure drop.
Technical Paper

Friction Calculations and Validation Measures on an External Component Test Bench of the Piston Pin Bearing under the Influence of Greater Elastic Deformation Caused by a Hydrostatic Bearing

2021-09-05
2021-24-0001
Increasing combustion pressure, low viscosity oils, less oil supply and the increasing stress due to downsizing of internal combustion engines (ICE) lead to higher loads within the bearing. As the mechanical and tribological loads on the piston pin bearings have a direct impact on the service life and function of the overall engine system, it is necessary to develop a robust tribological design approach. Regarding the piston pin bearing of a diesel engine, this study aims to describe the effects of different parameters on a DLC-coated piston pin within the bearing. Therefore, an external engine part test rig, which applies various forces to the connecting rod and measures the torque on a driven pin, is used to carry out validation measurements. The special feature of the test bench is the way the piston is beared. For the first experiments, the piston crown is placed against a plate (plate-bearing); later, this plate-bearing is replaced by a hydrostatic bearing.
Technical Paper

Simulation Study of a Turbocharged Two-Stroke Single Cylinder 425cc SI Engine

2021-09-05
2021-24-0003
An afterburner-assisted turbocharged single-cylinder 425 cc two-stroke SI-engine is described in this simulation study. This engine is intended as a Backup Range Extender (REX) application for heavy-duty battery electric vehicles (BEV) when external electric charging is unavailable. The 425 cc engine is an upscaled version of a 125 cc port-injected engine [26] which demonstrated that the selected technology could provide a specific power level of 400 kW/L and the desired 150 kW in a heavy duty BEV application. The 425 cc single cylinder two-stroke engine is an existing engine as one half of a 850 cc snowmobile engine. This simulation study includes upscaling of the swept volume, impact on engine speed and gas exchange properties. In the same way as for the 125cc engine [26], the exhaust gases reaches the turbine through a tuned exhaust pipe and an afterburner or oxidation catalyst.
Technical Paper

Development of a PN Surrogate Model Based on Mixture Quality in a GDI Engine

2021-09-05
2021-24-0013
A novel surrogate model is presented, which predicts the engine-out Particle Number (PN) emissions of a light-duty, spray-guided, turbo-charged, GDI engine. The model is developed through extensive CFD analysis, carried out using the Siemens Simcenter STAR-CD, and considers a range of part-load operating conditions and single-variable sweeps where control parameters such as start of injection and injection pressure are varied in isolation. The work is attached to the Ford-led APC6 DYNAMO project, which aims to improve efficiency and reduce harmful emissions from the next generation of gasoline engines. The CFD work focused on the air exchange, fuel spray and mixture preparation stages of the engine cycle. A combined Rosin-Rammler and Reitz-Diwakar model, calibrated over a wide range of injection pressure, is used to model fuel atomization and secondary droplets break-up.
Technical Paper

Combined CFD - Experimental Analysis of the In-Cylinder Combustion Phenomena in a Dual Fuel Optical Compression Ignition Engine

2021-09-05
2021-24-0012
Methane supply in diesel engines operating in dual fuel mode has demonstrated to be effective for the reduction of particulate matter and nitric oxides emissions from this type of engine. In particular, methane is injected into the intake manifold to form a premixed charge with air, while a reduced amount of diesel oil is still directly injected to ignite the mixture inside the cylinder. As a matter of fact, the liquid fuel burns following the usual diffusive combustion, so activating the gaseous fuel oxidation in a premixed flame. Clearly, the whole combustion process appears to be more complex to be described in a CFD simulation, mainly because it is not always possible to select in the 3-dimensional codes a different combustion model for each fuel and, also, because other issues arise from the interaction of the two fuels.
Technical Paper

Numerical Simulation of the Early Flame Development Produced by a Barrier Discharge Igniter in an Optical Access Engine

2021-09-05
2021-24-0011
Currently, conventional spark-ignition engines are unfit to satisfy the growing customer requirements on efficiency while complying with the legislations on pollutant emissions. New ignition systems are being developed to extend the engine stable operating range towards increasing lean conditions. Among these, the Radio-Frequency corona igniters represent an interesting solution for the capability to promote the combustion in a much wider region than the one involved by the traditional spark channel. Moreover, the flame kernel development is enhanced by means of the production of non-thermal plasma, where low-temperature active radicals are ignition promoters. However, at low pressure and at high voltage the low temperature plasma benefits can be lost due to occurrences of spark-like events. Recently, RF barrier discharge igniters (BDI) have been investigated for the ability to prevent the arc formation thanks to a strong-breakdown resistance.
Technical Paper

Potentials of the Oversizing and H2-Supported Lean Combustion of a VVA SI Gasoline Engine Towards Efficiency Improvement

2021-09-05
2021-24-0007
In recent years, internal combustion engine (ICE) downsizing coupled with turbocharging was considered the most effective path to improve engine efficiency at low load, without penalizing rated power/torque performance at full load. On the other side, issues related to knocking combustion and excessive exhaust gas temperatures obliged adopting countermeasures that highly affect the efficiency, such as fuel enrichment and delayed combustion. Powertrain electrification allows operating the ICE mostly at medium/high loads, shifting design needs and constraints towards targeting high efficiency under those operating conditions. Conversely, engine efficiency at low loads becomes a less important issue. In this track, the aim of this work is the investigation of the potential of the oversizing of a small Variable Valve ActuationSpark Ignition gasoline engine towards efficiency increase and tailpipe emission reduction.
Technical Paper

Experimental and Numerical Analyses of Direct and Port Water Injection in a Turbocharged Spark-Ignition Engine

2021-09-05
2021-24-0035
Water injection represents a promising tool to improve performance of spark-ignition engines. It allows reducing in-cylinder temperature, preventing knock risks. Optimizing the spark advance, water injection allows obtaining an increase of both efficiency and power output, particularly at medium and high loads. Water can be injected into the intake port or directly into the combustion chamber. In this paper, the authors investigated the effects of both direct and port water injection in a downsized PFI spark-ignition engine at high load operation. Different water-to-fuel ratios have been analyzed for both configurations. For the experimental analysis, low-pressure water injectors have been installed in the intake ports of the engine under study, upstream of the fuel injectors. Experimental tests have been carried out at various operating points. Furthermore, engine operation with port water injection has been simulated by means of the AVL Fire 3-D code.
Technical Paper

Towards a Complete Engine Calibration Methodology: Dynamic Design of Experiments (DDoE), Application to Catalyst Warm-Up Phase

2021-09-05
2021-24-0028
In recent years, engine calibration became a very hard task because of the increasing complexity of systems and the severity of the depollution norms regarding Real Driving Emissions (RDE). In particular, optimal engine control during dynamic phases became crucial for reducing pollutant emissions. Beyond the classical engine calibration method based on steady state experiments, methods that integrate the dynamical response of the engine constitute therefore a promising approach. This work proposes a global approach of engine dynamical model-based calibration (DMBC) and optimization based on a dynamic Design of Experiments (DDoE). After a general description of the architecture of the calibration process, the paper focuses on the methodology for the design of DDoE.
Technical Paper

Machine Learning Application to Predict Turbocharger Performance under Steady-State and Transient Conditions

2021-09-05
2021-24-0029
Performance predictions of advanced turbocharged engines are becoming difficult because conventional engine models are built using performance map data of turbochargers with a proportional integral derivative (PID) controller. Improving prediction capabilities under transient test cycles or real driving conditions is a challenging task. This study applies a machine learning technique to predict turbocharger performances with high accuracy under steady-state and transient conditions. The manipulated signals of engine speed and torque created based on Compressed High-Intensity Radiated Pulse (Chirp signal) and Amplitude-modulated Pseudo-Random Binary Signal (APRBS) are used as inputs to the engine testbed. Data from the engine experiments are used as training data for the AI-based turbocharger model. High prediction accuracy of the AI turbocharger model is achieved with the co-efficient of determination in the model, and cross-validation results are higher than 0.8.
Technical Paper

Avoidance Algorithm Development to Control Unrealistic Operating Conditions of Diesel Engine Systems under Transient Conditions

2021-09-05
2021-24-0025
Emission regulations are becoming tighter, and Real Driving Emissions (RDE) is proposed as a testing cycle for evaluating modern engine emissions under a wide operation range. For this reason, engine manufacturers have been developing a method to effectively assess engine performances and emissions under a wide range of transient conditions. Transient engine performances can be evaluated efficiently by applying time-series data created by chirp signals. However, when the time-series data produced by the chirp signal are used directly, the engine hardware may damage, and emission performances deteriorate drastically. It is therefore essential to develop a method to avoid these undesirable operating conditions. This work aims to develop an algorithm to avoid such unrealistic operation conditions for engine performance evaluation. A virtual diesel engine (VDE) model is developed based on a four-cylinder engine using GT-POWER software.
Technical Paper

Experimental and Numerical Investigation of the Flow Field Effect on Arc Stretching for a J-type Spark Plug

2021-09-05
2021-24-0020
Nowadays internal combustion engines can operate under lean combustion conditions to maximize efficiency, as long as combustion stability is guaranteed. The robustness of combustion initiation is one of the main issues of actual spark-ignition engines, especially at high level of excess-air or dilution. The enhancement of the in-cylinder global motion and local turbulence is an effective way to increase the flame velocity. During the ignition process, the excessive charge motion can hinder the spark discharge and eventually cause a misfire. In this perspective, the interaction between the igniter and the flow field is a fundamental aspect which still needs to be explored in more detail to understand how the combustion originates and develops. In this work, a combined experimental and numerical study is carried out to investigate the flow field around the spark gap, and its effect on the spark discharge evolution.
Technical Paper

Comparison of Velocity Field in a Single-Cylinder Transparent Internal Combustion Engine under Cold Flow Conditions Using Particle Image Velocimetry and Computational Fluid Dynamics

2021-09-05
2021-24-0021
Internal combustion engine will remain the major propulsion system for land transportation, for at least the next decade, as the transition to full electrification will not be imminent. Thus, it is important to improve the combustion efficiency and emissions. To achieve this, it is important to understand and control the in - cylinder flow evolution, and primarily the Tumble development as this is strongly connected with the mixing process. Flow field measurements were obtained by using Time Resolved Particle Image Velocimetry technique in a 475cc optical single - cylinder Gasoline Direct Injection (GDI) spark ignition engine. The results include 50 consecutive cycles phase averaged velocity fields at 2000 RPM with wide open throttle.
Technical Paper

Measurement of the Transmission Loss of Thin Panels Using the Two-Load Impedance Tube Method

2021-08-31
2021-01-1059
The two-load method is used to measure the transmission loss of thin panels in two different sized impedance tubes (3.49 cm and 10.16 cm). Samples were initially tested with a clamped boundary condition. This was followed by tests with an elastomer inserted between the tube and tested sample to adjust the boundary condition at the periphery. In all tests performed, the influence of the sample holding method could not be removed from the test. The measured transmission loss was compared to finite element simulation with good agreement for both impedance tubes. Additionally, the effect of a compliant boundary condition along the periphery of the sample was also validated via simulation.
Technical Paper

A Comparative Study between Abrasion Techniques to Improve the Adhesion of Rubber and Metal Bond for Commercial Vehicle Applications

2021-09-22
2021-26-0253
Engine mounts are an integral part of the vehicle that helps in reducing the vibrations generated from the engine. Engine mounts require a simple yet complicated amalgamation of two very different materials, steel and rubber. Proper adhesion between the two is required to prevent any part failure. Therefore, it becomes important that a comprehensive study is done to understand the mating phenomenon of both. A good linking between rubber and metal substrate is governed by surface pretreatment. Various methodologies such as mechanical and chemical are adopted for the same. This paper aims to present a comparative study as to which surface pretreatment has an edge over other techniques in terms of separation force required to break the bonding between the two parts. The study also presents a cost comparison between the techniques so that the best possible technique can be put to use in the commercial vehicle industry.
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