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Technical Paper

Variation in System Performance While Sorting DEF Heating Hardware Options

2018-09-10
2018-01-1813
The desire to reduce NOx at low ambient temperatures drives the use of heating methods to make DEF available by thawing the solution in the tank. Methods to validate modelling used to design hardware options require testing to gauge the accuracy of the prediction. Using a climatic chassis dynamometer (CCD) to demonstrate the guidance procedure set by the Environmental Protection Agency (EPA) is expensive and time consuming. A method of utilizing a flow controlled cooling supply combined with a standard cold chamber is described as a precursor to running the demonstration in the CCD. Testing multiple quantities of design iterations produced unexpected variation in the results. The sources of the variation and modifications taken to minimize them are discussed and presented. Test to test control of coolant flow, coolant temperature, and specific chamber temperature inconsistencies were found to be critically important to a successful effort.
Technical Paper

Strategies to define surrogate fuels for the description of the multicomponent evaporation behavior of hydrocarbon fuels

2018-09-10
2018-01-1692
Since real hydrocarbon fuels are commonly complex multi-component mixtures, their exact composition is generally neither known nor standardized. This makes the definition of surrogate mixtures to be used in simulations a crucial task to accurately model the evaporation and combustion behavior. Amongst others, this includes the specification of a certain numbers of surrogate components, the definition of optimization targets representing the real fuel properties of interest, the formulation of an appropriate numerical model for the evaluation of these quantities and the utilization of a suitable optimization algorithm to obtain the optimal surrogate composition. Concerning these points, several combinations can lead to a non-optimal representation of the real fuel target properties by the defined surrogate. A well-known example is the uncertainty in the numerical models often used for calculating the distillation curves measured by means of the ASTM D86 standard.
Technical Paper

Assessment of the New Features of a Prototype High-Pressure “Hollow Cone Spray” Diesel Injector by Means of Engine Performance Characterization and Spray Visualization

2018-09-10
2018-01-1697
The application of more efficient compression ignition combustion concepts requires advancement in terms of fuel injection technologies. The injector nozzle is the most critical component of the whole injection system. It is characterized by key factors as hole diameter, number, internal shape and opening angle. The reduction of the nozzle hole diameter seems the simplest way to increase the average fuel velocity and to promote the atomization process but the number of holes must be sufficient to deliver the desired fuel total mass. This logic has been applied to the development of a new generation of injectors. First, the tendency to increase the nozzle number and to reduce the diameter has led to the replacement of the nozzle with a circular plate. The vertical movement of the needle generates an annulus area for the fuel delivery on 360 degrees, so controlling the atomization as a function of the vertical plate position.
Technical Paper

Studies on the influence of engine conditions and different ash levels on the regeneration behavior of particulate filters

2018-09-10
2018-01-1704
Diesel particulate filters (DPF) are particularly effective devices to remove particulate matter (PM) from the diesel exhaust. In case of wall-flow filters, the particulates are deposited in the porous wall and on the surface of the filter channels. This results in an increase of the filter backpressure and thus has a negative impact on the engine performance and the fuel consumption. For this reason, the filter has to be regenerated periodically due to oxidation of the deposited PM. This oxidation behavior should result in an effective regeneration mode that minimizes the fuel penalty and limits the temperature rise while maintaining a high regeneration efficiency at the same time. However, this DPF operating behavior is influenced by the characteristics of the deposited and accumulated soot and ash, which is affected by different diesel engine operating parameters.
Technical Paper

Effect of Mesh Size in Numerical Simulation of Turbine Housing in Turbocharger

2018-09-10
2018-01-1715
Numerical method is popular in analyzing turbine housing in turbocharger with an early and rapid risk assessment. However, complex casting and extreme thermal loading from exhaust gas temperature and flow variation under engine duty cycle lead to big thermal stress and this makes material serviced in the plastic zone. Previous numerical simulations show that a mesh size is insensitive to the elastic finite element analysis (FEA), but might not be proper for elastic-plastic FEA, even that other boundary conditions keep same, which indicating simulation results are changeable with mesh size and a simple numerical mesh size convergence might not be enough to guarantee accurate numerical results as well. Therefore, several different mesh sizes are used in elastic-plastic analysis of turbine housing to investigate the influence on numerical results.
Technical Paper

Design Parameters for Small Engines based on Market Research

2018-09-10
2018-01-1717
Small internal combustion engines outperform batteries and fuel cells in regards to weight for a range of applications, including consumer products, marine vehicles, small manned ground vehicles, unmanned vehicles, and generators. The power ranges for these applications are typically between 1 kW and 10 kW. There are numerous technical challenges associated with engines producing power in this range resulting in low power density and high specific fuel consumption. As such, there is a large range of engine design solutions that are commercially available in this power range to overcome these technical challenges. A market survey was conducted of commercially available engines with power outputs less than 10 kW. The market data is analyzed to highlight the trade-offs between power output, engine weight, and specific fuel consumption.
Technical Paper

Effective Suppression of Surge Instabilities in Turbocharger Compression Systems through a Close-Coupled Compressor Inlet Restriction

2018-09-10
2018-01-1714
The current work demonstrates effective suppression of compression system surge instabilities by installing a variable cross-sectional flow area restriction within the inlet duct of a turbocharger centrifugal compressor operating on a bench-top facility. This restriction couples with the compressor, similar to stages in a multi-stage turbomachine, where the effective pressure ratio is the product of those for the restriction and compressor. During experiments at constant compressor rotational speed, the system is stable over the negatively sloped portion of the pressure ratio vs. flow rate characteristics, so the restriction is eliminated within this operating region to preserve compressor performance. At low flow rates, the slope of the compressor alone characteristics reaches a positive value, and the unrestricted compression system enters mild surge. Further reduction of flow rate with the unrestricted compressor inlet results in a sudden transition to deep surge instabilities.
Technical Paper

Effects of Hot and Cooled EGR for HC Reduction in a Dual-Fuel Premixed Charge Compression Ignition Engine

2018-09-10
2018-01-1730
Most internal combustion engine makers have adopted after-treatment systems, such as selective catalytic reduction (SCR), diesel particulate filter (DPF), and diesel oxidation catalyst (DOC), to meet emission regulations. However, as the emission regulations become stronger, the size of after-treatment systems is larger. It aggravates the price competitiveness of engine systems, and deteriorates fuel efficiency due to the increased exhaust pressure. Dual-fuel premixed charge compression ignition (DF-PCCI) combustion, which is one of advanced combustion technologies, is possible to reduce nitrogen oxides (NOx) and particulate matter (PM) during the combustion process, while keeping the combustion phase controllability as a conventional diesel combustion (CDC). However, DF-PCCI combustion produces high amounts of hydrocarbon (HC) and carbon monoxide (CO) emissions due to the bulk quenching phenomenon under low load conditions as a huddle of commercialization.
Technical Paper

Effect of thermocouple size on the measurement of internal combustion engine exhaust gas temperature

2018-09-10
2018-01-1765
Accurate measurement of exhaust gas temperature from internal combustion engines is essential for a large number of purposes including after-treatment systems, combustion modelling, and component durability. Discrepancy in such measurements could lead to inefficient hardware use or compromising the durability of engine components. Typically these measurements are made with thermocouples, which vary in size from 0.05 mm (for fast response applications) to a few millimetres. In this study, experimental testing supported by numerical simulations has been carried out in order to assess the performance of different size temperature sensors. Thus, the exhaust of a single cylinder diesel engine has been instrumented both with a fast-response probe (comprised of 0.002”, 0.005” and 0.01” thermocouples) and a 3 mm sheathed thermocouple and assessed under two speed/load conditions.
Technical Paper

Thermodynamic Analysis of an Evaporative Inlet Air Cooled Gas-Steam Combined Cycle for Marine Application:

2018-09-10
2018-01-1777
The integration of inlet air cooling to gas turbine based power utilities is a well accepted practice as this modification to the utility delivers superior utility performance. However, application of inlet-air cooling to drive turbines and specifically to marine mobility sector is rare in literature. Marine vessels are generally propelled by diesel engines, however large marine vessels specifically cruise ships and high speed naval vessels may have requirements of higher speeds and on-board power requirements which can fulfilled by gas turbine driving the propellers while on-board power needs can be met by steam turbine power generated from gas turbine exhaust heat. Such gas-steam combined cycles have the potential to become popular for high capacity marine vessels. The choice of gas turbine based combined cycle power plant for marine vessels in comparison to diesel engine powered vessel is also superior due to lower emission from the former.
Technical Paper

Effects of Different Injection Strategies and EGR on Partially Premixed Combustion

2018-09-10
2018-01-1798
Premixed Charge Compression Ignition concepts are promising to reduce NOx and soot simultaneously and keeping a high thermal efficiency. Partially premixed combustion is a single fuel variant of this new combustion concepts applying a fuel with a low cetane number to achieve the necessary long ignition delay. In this study, multiple injection strategies are studied in the partially premixed combustion approach to reach stable combustion and ultra-low NOx and soot emission at 15.5 bar gross indicated mean effective pressure. Three different injection strategies (single injection, pilot-main injection, main-post injection) are experimentally investigated on a heavy duty compression ignition engine. A fuel blend (70vol% n-butanol and 30vol% n-heptane) was tested. The effects of different pilot and post-injection timing, as well as Exhaust-gas Recirculation rate on different injection strategies are investigated.
Technical Paper

Investigation of oil sources in the combustion chamber of direct injection gasoline engines

2018-09-10
2018-01-1811
Investigation of oil sources in the combustion chamber of direct injection gasoline engines To reduce hydrocarbon and particle emission as well as irregular combustion phenomena the identification and quantification of possible oil sources in the combustion chamber of the direct injection gasoline engine is of main interest. The aim of the research activity is to fundamentally investigate the formation of locally increased lubricating oil concentrations in the combustion chamber. For this purpose, the oil sources are considered separately from each other and divided into the groups piston / compression ring and lubricating film on the liner. The associated oil emission and its influence on the engine combustion are the core of the investigations.
Technical Paper

Numerical investigation of Syngas fuelled HCCI engine using stochastic reactor model with detailed chemical kinetic mechanism

2018-09-10
2018-01-1661
Scarcity and economic swings of fossil derived fuels (mainly gasoline and diesel) have augmented the need for the utilization of alternative fuels in internal combustion (IC) engines. Additionally increasing global environmental concerns due to higher greenhouse gas emissions have stressed the importance for efficiency and emissions research. Research in utilization of hydrogen and syngas has significantly increased due to their clean burning properties and the prospect of production from several renewable resources. Homogeneous charge compression ignition (HCCI) engine is low temperature combustion concept which combines the best features of conventional spark-ignition (SI) and compression-ignition (CI) engines. HCCI combustion engine have shown the potential for higher efficiency and ultralow NOx and soot emissions. In this study syngas fuelled HCCI combustion is simulated using stochastic reactor model (SRM) with detailed chemical kinetic mechanism (32 species and 173 reactions).
Technical Paper

Development of a New 1.8L Down-Speeding Turbocharged Gasoline Engine with Miller Cycle

2018-09-10
2018-01-1712
A 1.8L down-speeding turbocharged gasoline engine was developed to upgrade an existing 2.0L NA engine, towards achieving both driving and environmental requirements which including China 4th stage fuel consumption regulation and China 6a emission legislation. The engine is intended to replace 2.0-2.3L class NA engine. Firstly, the concept of this engine and main parameters was explained to meet the excellent part-load BSFC and low end torque. Due to the lower valve lift with miller cycle, valve masking below the intake valve seat is required for optimal gas-exchange, increasing charge motion. The valve angle was changed from 23°/24.5°to 18°/18°so as to have space available to apply masking. During the development process, low speed pre-ignition occurred as expected since the higher torque target and compression ratio just only with port injection.
Technical Paper

Structural Integrity of In-Wheel Motors

2018-09-10
2018-01-1829
In-wheel motors offer an optimized solution for novel drivetrain architectures of future electric vehicles that could penetrate into the mainstream automotive industry, moving the wheel actuation where it’s required, directly inside the wheels. Obtainable literature mainly deals with optimization of electromagnetically active parts, however, mechanical design of electromagnetically passive parts that indirectly influence motor performance also require detailed analysis and extensive validation.
Technical Paper

A Simplified Test Campaign for 0D Map-Based Powertrain Modelling applied to 48V Mild-Hybrid Diesel Passenger Car

2018-09-10
2018-01-1659
Although high-voltage (HV) system vehicles, such as electric vehicles (EVs), plug-in hybrid (PHEVs) and full hybrid electric vehicles (HEVs), will probably dominate the automotive market in the future, 48V architecture seems to be the perfect bridge between the 12V system and costly HV electrification. The 48V network enables the implementation of mild hybrid cost-effective strategies towards the crucial goal of CO2 and pollutants reduction in combination with enhanced performance. Besides, compared to a conventional powertrain, the mild-hybrid approach leads to an increased complexity in the interaction between different sub-systems targeting the optimization of the Energy Management System (EMS). Therefore, it becomes essential to perform a preliminary hardware assessment, exploring the interactions between the different components and quantifying the cost vs benefit trade-off.
Technical Paper

Statistical Study of Ring Geometry Effect on Piston Ring/Liner Tribology Using Classical Design of Experiment

2018-09-10
2018-01-1658
An instantaneous piston ring/liner friction model has been presented to estimate the minimum oil film thickness and power loss contributed by piston rings under hydrodynamic lubrication. The model is based on lubrication theory considering lubricant viscosity variation with respect to temperature. A numerical scheme is developed to solve Reynolds and load equilibrium equations simultaneously to obtain the cyclic variation of oil film thickness and power loss. The model considers the ring profile geometry, the ring mechanical properties and their effects on the tribological performance of piston ring. The relevant trends and relations between parameters are considered with relatively simple approach to compute the minimum oil film thickness and mechanical power loss.
Technical Paper

Effectiveness of fuel enrichment on knock suppression in a boosted gasoline engine

2018-09-10
2018-01-1665
Knock, and more recently, super-knock, have always been a limiting factor on improving engine efficiency. As a result, engines often operate rich at high loads to both avoid damage resulting from knock and protect the aftertreatment system from excessive thermal stress. In this work, port and direct injection of excess fuel has been explored as a mechanism to suppress knock and super-knock. Under naturally aspirated conditions, increasing fuel enrichment initially increases knock intensity, and further increase, then decreases knock intensity. Competing mechanism from calorific value and latent heat of vaporization explain the phenomenon. However, when direct injecting the excess fuel after the spark has been fired, knock intensity monotonically decreases with increasing fuel quantity. This decrease is shown to be due to fuel quenching the flame propagating from spark location. Under boosted conditions, the amount of fuel injected is of critical importance in avoiding super-knock.
Technical Paper

Distribution of Knock Frequencies in Modern Engines Compared to Historical Data

2018-09-10
2018-01-1666
It is widely known that the rapid autoignition of end-gas will cause an engine cylinder to resonate, creating a knocking sound. These effects were quantified for a standard cylindrical engine geometry in 1938 where critical resonance frequencies were identified. These frequencies are often still considered to be the standard knock frequencies. However, the resonance frequencies are highly dependent on the engine geometry and the conditions inside the cylinder at autoignition. Since, engines and fuels operate at substantially different conditions than they did in 1938, it is expected that there should be a shift in knock frequencies. Experimental tests were run to collect knock data in an engine representative of modern geometries, over a range of operating conditions for a number of different fuels. The operating condition parameters, to include intake air temperature, intake air pressure, and engine speed, were varied to identify shifts in the critical frequencies.
Technical Paper

Effect of mixture formation and injection strategies on stochastic pre-ignition

2018-09-10
2018-01-1678
Downsizing and downspeeding have led to efficiency improvements in spark-ignited engines. However, pre-ignition remains one of the major barriers impeding further improvements from this strategy. One of the most widely cited mechanisms thought to be responsible for pre-ignition is the ignition of a rogue droplet composed of lubricant oil and fuel. This rogue droplet is made possible by interactions between the fuel spray and oil on the cylinder liner during the gasoline-in-air mixture formation. In the present study, the rogue droplet hypothesis is examined using a single cylinder supercharged engine that employs a range of gasoline-in-air mixture formation strategies. These include port-fuel injection along with side and central direct injection of an E5 gasoline using single and multiple injection events. Computational fluid dynamic (CFD) calculations are then used to explain the trends observed experimentally.
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