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When performing catalyst modeling and parameter tuning it is desirable that the experimental data contain both transient and stationary points and can be generated over a short period of time. Here a method of creating such concentration transients for a full scale engine rig system is presented. The paper describes a valuable approach for changing the composition of engine exhaust gas going to a DOC (or potentially any other device) by conditioning the exhaust gas with an additional upstream DOC and/or SCR. By controlling the urea injection and the DOC bypass a wide range of exhaust compositions, not possible by only controlling the engine, could be achieved. This will improve the possibilities for parameter estimation for the modeling of the DOC.

Parameter tuning was performed against data from a full scale engine rig with a Diesel Oxidation Catalysts (DOC). Several different catalyst configurations were used with varying Pt loading, washcoat thickness and volume. To illustrate the interplay between kinetics and mass transport, engine operating points were chosen with a wide variation in variables (inlet conditions) and both transient and stationary operation was used. A catalyst model was developed where the catalyst washcoat was discretized as tanks in series both radially and axially. Three different model configurations were used for parameter tuning, evaluating three different approaches to modeling of internal transport resistance. It was concluded that for a catalyst model with internal transport resistance the best fit could be achieved if some parameters affecting the internal mass transport were tuned in addition to the kinetic parameters.

This paper presents pressure drops and heat transfer rates for compact heat exchangers, where the heat exchangers are angled 90°, 60°, 30° and 10° relative to the incoming airflow. The investigation is based on three heat exchangers with thicknesses of 19mm and 52mm. Each heat exchanger was mounted in a duct, where it was tested for thermal and isothermal conditions. The inlet temperature of the coolant was defined to two temperatures; ambient temperature and 90°C. For the ambient cases the coolant had the same temperature as the surrounding air, these tests were performed for five airflow rates. When the coolant had a temperature of 90°C a combination of five coolant flow rates and five airflow rates were tested. The test set-up was defined as having a constant cross-section area for 90°, 60° and 30° angles, resulting in a larger core area and a lower airspeed through the core, for a more inclined heat exchanger.

Nowadays, much focus for vehicle manufacturers is directed towards improving the energy efficiency of their products. The aerodynamic drag constitutes one major part of the total driving resistance for a vehicle travelling at higher speeds. In fact, above approximately 80km/h the aerodynamic drag is the dominating resistance acting on a truck. Hence the importance of reducing this resistance is apparent. Cooling drag is one part of the total aerodynamic drag, which arises from air flowing through the heat exchangers, and the irregular under-hood area. When using Computational Fluid Dynamics (CFD) in the development process it is of great importance to ensure that the methods used are accurately capturing the physics of the flow. This paper deals with comparative studies between CFD and wind-tunnel tests. In this paper, two comparative studies are presented.

On page 1103, the published paper omitted important text before and after figure 6.

This article presents Computational Fluid Dynamics (CFD) simulations fo one period of a louvered fin, for a crossflow compact finned heat exchanger, where the incoming airflow was inclined relative to its core. Four inclinations were investigated: 90°, which was when the air flowed perpendicular to the heat exchanger, 60°, 30° and 10° angles relative to the vertical plane. The study included three heat exchanger designs, where two of them had symmetrical louvered fins and a thickness of 19mm and 52mm. The third had a thickness of 19mm and had the louvers angled in one direction. All heat exchangers have been simulated when the airflow entered both from above and below relative to the horizontal plane. Simulations have also been carried out when the airflow entered from the side, illustrating the heat exchanger to be angled relative to the vertical axis. Two air speeds have been investigated for each configuration, where the results were compared to experimental data.

Boosting and stratified operation can be used to increase the fuel efficiency of modern gasoline direct-injected (GDI) engines. In modern downsized GDI engines, boosting is standard to achieve a high power output. However, boosted GDI-engines have mostly been operated in homogenous mode and little is known about the effects of operating a boosted GDI-engine in stratified mode. This study employed optical and metal engines to examine how boosting influences combustion and particulate emission formation in a spray-guided GDI (SGDI), single cylinder research engine. The setup of the optical and metal engines was identical except the optical engine allowed optical access through the piston and cylinder liner. The engines were operated in steady state mode at five different engine operating points representing various loads and speeds. The engines were boosted with compressed air and operated at three levels of boost, as well as atmospheric pressure for comparison.

Quantification of heat exchanger performance in its operative environment is in many engineering applications an essential task, and the air flow rate through the heat exchanger core is an important optimizing parameter. This paper explores an alternative method for quantifying the air flow rate through compact heat exchangers positioned in the underhood of a passenger car. Unlike conventional methods, typically relying on measurements of direct flow characteristics at discrete probe locations, the proposed method is based on the use of load-cells for direct measurement of the total force acting on the heat exchanger. The air flow rate is then calculated from the force measurement. A direct comparison with a conventional pressure based method is presented as both methods are applied on a passenger car’s radiator tested in a full scale wind tunnel using six different grill configurations. The measured air flow rates are presented and discussed over a wide range of test velocities.

The development of high efficiency powertrains is a key objective for car manufacturers. One approach for improving the efficiency of gasoline engines is based on homogeneous charge compression ignition, HCCI, which provides higher efficiency than conventional strategies. However, HCCI is only currently viable at relatively low loads, primarily because at high loads it involves rapid combustion that generates pressure oscillations in the cylinder (ringing), and partly because it gives rise to relatively high NOX emissions. This paper describes studies aimed at increasing the viability of HCCI combustion at higher loads by using fully flexible valve trains, direct injection with charge stratification (SCCI), and intake air boosting. These approaches were complemented by using EGR to control NOX emissions by stoichiometric operation, which enables the use of a three-way catalyst.

The aim of the study was to investigate the cooling performance of two cooling package positions for distribution vehicles by using Computational Fluid Dynamics. The first cooling package was positioned in the front of the vehicle, behind the grill and the second position was at the rear of the vehicle. Each case was evaluated by its cooling performance for a critical driving situation and its aerodynamic drag at 90 km/h, where the largest challenge of an alternative position is the cooling air availability. The geometry used was a semi-generic commercial vehicle, based on a medium size distribution truck with a heat rejection value set to a fixed typical level at maximum power for a 13 litre Euro 6 diesel engine. The heat exchangers included in the study were the air conditioning condenser, the charge air cooler and the radiator. It was found that the main problem with the rear mounted cooling installation was the combination of the fan and the geometry after the fan.

Passive selective catalyst reduction (SCR) systems can be used as aftertreatment systems for lean burn spark ignition (SI)-engines. Their operation is based on the interaction between the engine, an ammonia formation catalyst (AFC), and an SCR catalyst. Under rich conditions the AFC forms ammonia, which is stored in the SCR catalyst. Under lean conditions, the SCR catalyst reduces the engine out NOx using the stored NH3. This study compared the ammonia production and response times of a standard three way catalyst (TWC) and a Pd/Al2O3 catalyst under realistic engine operating conditions. In addition, the relationships between selected engine operating parameters and ammonia formation over a TWC were investigated, considering the influence of both the chosen load point and the engine settings.

This investigation is a continuing analysis of the cooling performance and aerodynamic properties of a rear-mounted cooling module on a semi-generic commercial vehicle, which was carried out by Larsson, Löfdahl and Wiklund. In the previous study two designs of the cooling package installation were positioned behind the rear wheelhouse and the results were compared to a front-mounted cooling module. The investigation was mainly focused on a critical cooling situation occurring at lower vehicle speeds for a local distribution vehicle. The conclusion from the study was that the cooling performance for one of the rear-mounted installation was favorable compared to the front-mounted cooling package. This was mainly due to the low vehicle speed, the high fan speed and to fewer obstacles around the cooling module resulting in a lower system restriction within the installation.

In order to quantify fuel-cut aging effects on commercial bimetallic Pd/Rh three-way catalysts (TWCs), supported on cerium-zirconium promoted alumina, full-size automotive catalysts were exposed to accelerated fuel-cut aging on an engine test bench, with a variation in temperature, fuel-cut frequency and fuel-cut duration. After aging, samples of the catalysts were tested in a laboratory environment for Light-off temperature (T50), Specific surface area (BET), Dispersion of noble metals and changes in the oxidation state of Pd and Rh. The catalytic tests showed clear deactivation of the aged samples and influence on the TWC's properties. The light off temperature and noble metal dispersion were found to be a clear function of oxygen exposure to the catalysts, i.e. fuel-cut frequency and duration, while the specific surface area was found to be a function of fuel-cut frequency. No changes in oxidation states of Pd and Rh could be detected.

The EU emission standards for new rail Diesel engines are becoming even more stringent. EGR and SCR technologies can both be used to reduce NOx emissions; however, the use of EGR is usually accompanied by an increase in PM emissions and may require a DPF. On the other hand, the use of SCR requires on-board storage of urea. Thus, it is necessary to study these trade-offs in order to understand how these technologies can best be used in rail applications to meet new emission standards. The present study assesses the application of these technologies in Diesel railcars on a quantitative basis using one and three dimensional numerical simulation tools. In particular, the study considers a 560 kW railcar engine with the use of either EGR or SCR based solutions for NOx reduction. The NOx and PM emissions performances are evaluated over the C1 homologation cycle.

A regular flex-fuel engine can operate on any blend of fuel between pure gasoline and E85. Flex-fuel engines have relatively low efficiency on E85 because the hardware is optimized for gasoline. If instead the engine is optimized for neat ethanol, the efficiency may be much higher, as demonstrated in this paper. The studied two-liter engine was modified with a much higher compression ratio than suitable for gasoline, two-stage turbocharging and direct injection with piezo-actuated outwards-opening injectors, a stratified combustion system and custom in-house control system. The research engine exhibited a wide-open throttle performance similar to that of a naturally aspirated v8, while offering a part-load efficiency comparable to a state-of-the-art two-liter naturally aspirated engine. NOx will be handled by a lean NOx trap. Combustion characteristics were compared between gasoline and neat ethanol.

An important objective in combustion engine research is to develop strategies for recovering waste heat and thereby increasing the efficiency of the propulsion system. Waste-heat recovery systems based on the Rankine cycle are the most efficient tools for recovering energy from the exhaust gas and the Exhaust Gas Recirculation (EGR) system. The properties of the working fluid and the expansion machine have significant effects on Rankine cycle efficiency. The expansion machine is particularly important because it is the interface at which recovered heat energy is ultimately converted into power. Parameters such as the pressure, temperature and mass-flow conditions in the cycle can be derived for a given waste-heat source and expressed as dimensionless numbers that can be used to determine whether displacement expanders or turbo expanders would be preferable under the circumstances considered.

Among many techniques used for increasing fuel efficiency of a modern Gasoline Direct-Injected (GDI) engine are boosting and stratified operation. In modern downsized GDI engines, boosting is standard in order to achieve a high power output. Boosted GDI-engines have however mostly been operated in homogenous mode and little is known on the effects of operating a boosted GDI-engine in stratified mode. This paper presents the influence on combustion, standard emissions and particulate size distribution in a Spray-Guided, Gasoline, Direct-Injected (SGDI), single cylinder, research engine operated with various levels of boost. The engine was operated in steady state mode at five engine operating points of various load and speed. The engine was boosted with a Roots blower and operated at four levels of boost as well as atmospheric pressure for comparison. The engine was fueled with market gasoline (95 RON) blended with 10% ethanol.

The effect of various fuel-cut agings, on a Volvo Cars 4-cylinder gasoline engine, with bimetallic three-way catalysts (TWCs) was examined. Deactivation during retardation fuel-cut (low load) and acceleration fuel-cut (high load, e.g. gearshift or traction control) was compared to aging at λ=1. Three-way catalysts were aged on an engine bench comparing two fuel-cut strategies and their impact on of the life and performance of the catalysts. In greater detail, the catalytic activity, stability and selectivity were studied. Furthermore, the catalysts were thoroughly analyzed using light-off and oxygen storage capacity measurements. The emission conversion as a function of various lambda values and loads was also determined. Fresh and 40-hour aged samples showed that the acceleration fuel-cut was the strategy that had the highest contribution towards the total deactivation of the catalyst system.

This study investigated how the amount of dilution applied can be extended while maintaining normal engine operation in a GDI engine. Adding exhaust gases or air to a stoichiometric air/fuel mixture yields several advantages regarding fuel consumption and engine out emissions. The aim of this paper is to reduce fuel consumption by means of diluted combustion, an advanced ignition system and adjusted valve timing. Tests were performed on a Volvo four-cylinder engine equipped with a dual coil ignition system. This system made it possible to extend the ignition duration and current. Furthermore, a sweep was performed in valve timing and type of dilution, i.e., air or exhaust gases. While maintaining a CoV in IMEP < 5%, the DCI system was able to extend the maximum lambda value by 0.1 - 0.15. Minimizing valve overlap increased lambda by an additional 0.1.

To contribute to knowledge required to meet new emission requirements, relationships between multiple injection parameters, degrees of fuel stratification, combustion events, work output and flame luminosity (indicative of particulate abundance) were experimentally investigated using a single-cylinder optical GDI engine. A tested hypothesis was that advancing portions of the mass injected would enhance the fuel-air mixing and thus reduce flame luminescence. An outward-opening piezo actuated fuel injector capable of multiple injections was used to inject the fuel using different triple injection strategies, with various combinations of late and earlier injections leading to various degrees of fuel stratification. Sprays and combustion events were captured using two high-speed cameras and cylinder pressure measurements.