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Energy Recovery Rate from an Electric Air-cycle System under the Cruising Altitude and Speed.

Akita University-Takahiro Adachi
  • Technical Paper
  • 2019-01-1905
To be published on 2019-09-16 by SAE International in United States
In this study, we focus on an electric air-cycle system in an electric aircraft, where the system has an electric compressor instead of a hydraulically-operated oil-based compressor. The electric compressor consumes the power to compress the rarefied air outside and take it in the system. The air goes through the air-cycle as a working fluid to exchange the heat and work. The main purpose of the air-cycle is to adjust the temperature and pressure in a cabin. Therefore, the working fluid of the air repeats compression and expansion. The working fluid passing through the cabin absorbs heat from the passengers and avionics. After that, the air is discharged outside with higher heat level and pressure levels. This means that the discharged air has a potential energy to recover the power consumption in the electric compressor. So, we have analytically estimated an energy recovery rate which is defined as a ratio of the potential energy of the discharged air to the energy consumption in the compressor, and shown the recovery rate under the condition of cruising…

Analysis of a Coupling System of Aircraft Environmental Control and Fuel Tank Inerting Based on Membrane Separation

Beihang University-Weixing Yuan, Jiaqi Hou
CAPDI-Yan zheng
  • Technical Paper
  • 2019-01-1895
To be published on 2019-09-16 by SAE International in United States
This paper raises a coupling system of aircraft environmental control and fuel tank inerting based on membrane separation. The system applies a membrane dehumidifier to replace water vapor removal unit of heat regenerator, condenser and water separator, which is widely used in conventional aircraft environmental control system nowadays. Water vapor can travel across the membrane wall under its pressure difference without phase change, so the dehumidification process consumes no cooling capacity and the cooling capacity of the system increases. This paper first compares the thermodynamic properties of environmental control system based on membrane dehumidification and the environmental control system based on condensation. The results show that the membrane dehumidification system has bigger cooling capacity and lighter weight. For a given cooling capacity requirement of a certain aircraft, the membrane dehumidification system can use less bleed air since the temperature of the outlet air is lower. Nowadays, the fuel tanking inerting system also uses an air separation module to produce nitrogen enriched air based on membrane separation. After the air is dehumidified in membrane environmental control…

Experimental investigations on engine-out emissions sensitivity to fuel injection pressure of a high-performance DISI single cylinder engine

Ferrari S.p.A.-Vincenzo Rossi, Nicola Silvestri, Massimo Medda
  • Technical Paper
  • 2019-24-0169
To be published on 2019-08-15 by SAE International in United States
In recent times complying with increasingly stringent emission regulations has become ever more challenging. While an efficient after-treatment system that includes gasoline particulate filter enables compliance with legislation requirements, lowering engine-out emissions by improving combustion system has to be considered as a crucial advantage not only in regard to pollutants emission control, but also performance. In this respect, high-performance enabling contents such as relatively large displacement, flow-capacity oriented intake ports and a limited stroke-to-bore ratio have significant drawbacks on the charge motion quality and as direct consequence on mixture formation and homogeneity. As a countermeasure, fuel injection system components as well as control strategies need to be substantially improved; on the control side the increase of fuel injection pressure coupled with optimized injection timing and splitting, has proved to be effective in reducing emissions, with special regard to particulate matter. This paper provides results of an experimental study investigating the effect of different fuel injection strategies on engine-out emissions, with special emphasis on the influence of very high fuel injection pressures (up to 50 MPa)…

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

Daimler AG-Christian HENNES, Jürgen Lehmann
KIT Karlsruhe Institute Of Technology-Thomas Koch
  • Technical Paper
  • 2019-24-0171
To be published on 2019-08-15 by SAE International in United States
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. As this is not done before for a heavy-duty engine, with peak pressures up to 250 bar, an increased in-cylinder turbulence and high EGR-rates is presented the following. The different methods to determine…

Experimental characterization of methane direct injection from an outward-opening poppet-valve injector

Istituto Motori CNR-Maurizio Lazzaro, Francesco Catapano, Paolo Sementa
  • Technical Paper
  • 2019-24-0135
To be published on 2019-08-15 by SAE International in United States
The in-cylinder direct injection of natural gas represents a further step towards cleaner and more efficient internal combustion engines (ICE). However, the injector design and its characterization, either experimentally or from numerical simulation, is challenging because of the complex fluid dynamics related to gas compressibility. In this work, the underexpanded flow of methane from an outward-opening poppet-valve injector has been experimentally characterized by Schlieren and Shadowgraph high-speed imaging. The jet evolution was also followed through Mie-scattering imaging using n-heptane droplets as a tracer. The investigation has been performed at ambient temperature and pressure and different nozzle pressure ratios (NPR) ranging from 10 to 17. The gaseous jet has been characterized in terms of its macroscale parameters.

Performance and Emissions of an Ammonia-Fueled SI Engine with Hydrogen Enrichment

Universite D'Orleans-Pierre BREQUIGNY, Christine Rousselle
Université D'Orleans-Charles Lhuillier
  • Technical Paper
  • 2019-24-0137
To be published on 2019-08-15 by SAE International in United States
While the optimization of the internal combustion engine (ICE) remains a very important topic, alternative fuels are also expected to play a significant role in the reduction of CO2 emissions. High energy densities and handling ease are their main advantages amongst other energy carriers. Ammonia (NH3) additionally contains no carbon and has a worldwide existing transport and storage infrastructure. It could be produced directly from renewable electricity, water and air, and is thus currently considered as a smart energy carrier and combustion fuel. However, ammonia presents a low combustion intensity and the risk of elevated N-based emissions, thus rendering in-depth investigation of its suitability as an ICE fuel necessary. In the present study, a recent single-cylinder GDI SI engine is fueled with gaseous ammonia/hydrogen/air mixtures at various hydrogen fractions, equivalence ratios and intake pressures. Hydrogen is used as combustion promoter and might be generated in-situ through NH3 catalytic dissociation. In-cylinder pressure and exhaust concentrations of selected species are recorded and analyzed. Results show that ammonia is a very suitable fuel for SI engine operation, since…

Optimization of the Exhaust Aftertreatment System of a Heavy Duty Engine by means of Variable Valve Timing

Technische Universität Braunschweig-Marius Betz, Peter Eilts
  • Technical Paper
  • 2019-24-0143
To be published on 2019-08-15 by SAE International in United States
In view of the current political debate, it can be assumed that the nitrogen oxide limits for commercial vehicles will be further reduced. This is also demonstrated by the currently voluntary certification of the CARB Optional Low NOX legislation, which requires nitrogen oxide emissions of 0.027 g / kWh. This corresponds to a reduction of 93% compared to the current EU VI standard. Therefore, the optimization of EAT systems represents an essential research focus for future commercial vehicle applications. One way to optimize the EAT system may be the usage of variable valve actuation. Existing investigations show an exhaust gas temperature increase with Miller timing, but the authors conclude that it cannot accelerate the heating process. With regard to the effects on the exhaust aftertreatment system and the resulting tailpipe emissions, only improved HC and CO oxidation could be identified so far. In addition, a potential for improved NOX reduction is expected in the exhaust gas temperature increase. Therefore, investigations are carried out at the Institute of Internal Combustion Engines of the Technical University of…

Injection Pattern Investigation for Gasoline Partially Premixed Combustion Analysis

MAGNETI MARELLI SpA - Div. Powertrain-Federico Stola, Matteo De Cesare
University of Bologna-Fabrizio Ponti, Vittorio Ravaglioli, Giacomo Silvagni
  • Technical Paper
  • 2019-24-0112
To be published on 2019-08-15 by SAE International in United States
Nowadays, compression-ignited engines are considered the most efficient and reliable technology for automotive applications. However, mainly due to the current emission regulations, that require increasingly stringent reductions of NOx and particulate matter, the use of diesel-like fuels is becoming a critical issue. For this reason, a large amount of research and experimentation is being carried out to investigate innovative combustion techniques suitable to simultaneously mitigate the production of NOx and soot, while improving engine efficiency. In this scenario, the combined use of compression-ignited engines and gasoline-like fuels proved to be very promising, especially in case the fuel is directly-injected in the combustion chamber at high pressure. The presented study analyzes the combustion process produced by the direct injection of gasoline in a compression-ignited light-duty engine. The engine under investigation has been modified to guarantee a stable engine operation over its whole operating range, that is achieved controlling boost pressure and temperature together with the design of the multiple injections pattern. The analysis of the experimental tests highlights the impact of several control variables on combustion…

Sensitivity Analysis of the Combustion Parameters in a Stratified HCCI Engine with Regard to Performance and Emission

mahboud Armin
Mazandaran university of science and tec-Mohsen Pourfallah
  • Technical Paper
  • 2019-24-0114
To be published on 2019-08-15 by SAE International in United States
Homogeneous charge compression ignition (HCCI) is a promised solution to environmental and fuel economy concerns for IC engines. Engine application for HCCI engine depends on an array of parameters such as fuel type, mixture composition, intake condition and engine specification, meaning that controlling an HCCI engine can only be done through the adjustment of these parameters. In this numerical study which is driven from an experimental work, thermal and charge stratification is used to control HCCI combustion. The effect of intake temperature, compression ratio, intake pressure, EGR, reformer gas (CO-H2 mixture) and glow plug temperature on engine performance and emission was investigated using a 3D model on AVL-FIRE parallel with 1D model on GT-Power software. Then AHP model as a multiple Attribute Decision making method has been used to analyze the sensitivity of these parameters on performance and emission. Results indicate that increasing intake temperature causes the operating condition approaches knock which results in a narrower operating region. Increasing EGR ratio makes possible the expanding of operating range rich limit since it causes delayed combustion…

Large eddy simulation of an ignition wave front in a heavy duty partially premixed combustion engine

Lund Univ.-Christian Ibron
Lund University-Hesameddin Fatehi, Mehdi Jangi, Xue-Song Bai
  • Technical Paper
  • 2019-24-0010
To be published on 2019-08-15 by SAE International in United States
In partially premixed combustion engines high octane number fuels are injected into the cylinder during the late part of the compression cycle, giving the fuel and oxidizer enough time to mix into a desirable stratified mixture. If ignited by auto-ignition such a gas composition can react in an ignition wave-front dominated combustion mode. 3D-CFD modeling of such a combustion mode is challenging as the reaction speed is dependent on both mixing history and turbulence acting on the reaction wave. This paper presents a large eddy simulation (LES) study of the effects of energetic turbulence scale on the fuel/air mixing and on the propagation of reaction wave. The results are compared with optical experiments to validate both pressure trace and ignition location. The studied case is a closed cycle simulation of a single cylinder of a Scania D13 engine running PRF81 (81% iso-octane and 19% n-heptane). One-equation-eddy transported SGS-turbulence closure is used in the LES; the fuel spray is modelled using an Lagrangian particle tracking (LPT) approach. The coupling of flow and chemical reactions is done…