Effect of Butanol on the Performance of DeNOx Aftertreatment Systems of a Diesel Vehicle Under WLTC Driving Conditions

Advanced biofuels and electrofuels, among which are medium-long chain alcohols, have gained importance in the transport sector with the enforcement of the EU Renewable Energy Directive (2018/2001). In parallel, last European emission regulations have become much more restrictive regarding NOx, so vehicle manufacturers have been forced to incorporate lean NOx trap (LNT) and/or selective catalytic reduction (SCR). Thus, the combination of modern DeNOx devices and the upcoming higher contribution of sustainable biofuels is a new challenge. In this work, two Euro 6 diesel vehicles, one equipped with LNT and the other with ammonia-SCR, have been tested following the Worldwide harmonized Light-duty vehicles Test Cycle (WLTC) at warm (24°C) and cold (−7°C) conditions using conventional diesel fuel and a diesel-butanol (90/10% vol.) blend. While the effect of butanol on the LNT efficiency was not significant, its influence on the SCR performance was notable during the low and medium-speed phases of the driving cycle, mainly under warm climatic conditions. Despite of the lower NOx concentration at the catalyst inlet, the worst efficiency of the SCR with butanol could be attributed to hydrocarbons deposition on the catalyst surface, which inhibits the NOx reduction reactions with ammonia. Moreover, the LNT was not sensitive to the ambient temperature while the SCR performance greatly depended on this parameter.

Electrification of Compact Off-Highway Vehicles—Overview of the Current State of the Art and Trends

Electrified vehicles have undergone great evolution during the last decade because of the increasing attention paid on environmental sustainability, greenhouse gas emissions and air pollution. Emission regulations are becoming increasingly tight, and governments have been allocating multiple funds to facilitate the spreading of the so-called green mobility. In this context, steering towards electrified solutions not only for passenger vehicles, but also for compact off-highway vehicles extensively employed, for instance, on construction sites located in urban areas, warehouses, and greenhouses, is essential even if seldom considered. Moreover, the electrification of compact off-highway machinery may allow manufacturers to increase their expertise in and lower the costs of these alternative solutions, while gathering useful data to be applied in bigger and more remunerative off-highway vehicles. In fact, while electric automobiles are as of now real alternatives for buyers, off-highway vehicles, regardless of the application, are mostly in the research and experimental phase, with few of them already on the market. This delay, in comparison with the passenger automotive industry, is caused by different factors, mostly related to the different tasks of off-highway vehicles in terms of duty cycles, productivity performance parameters and user acceptability. The aim of this paper is to give an overview of the many aspects of the electrification of compact off-highway vehicles, to highlight the key differences between on-highway and off-highway vehicles and to summarize in a single source of information the multiple solutions investigated by researchers and manufacturers.

An optimization-based design approach for a novel self-adjuster using shear thickening fluid

Recently, the increasingly strict safety and emission regulations in the automotive industry drove the interest towards automatic length compensating devices, e.g., hydraulic lash adjusters (lower emission) and slack adjuster in brake systems (faster brake response). These devices have two crucial requirements: (a) be stiff during high load, while (b) be flexible in the released state to compensate for environmental effects such as wear and temperature difference. This study aims to use the advantageous properties of shear thickening fluids to develop a less complicated, cost-efficient design. The proposed design is modeled by a system of ordinary differential equations in which the effect of the non-Newtonian fluid flow is taken into account with a novel, simplified, semi-analytical flow rate-pressure drop relationship suitable for handling arbitrary rheology. The adjuster’s dimensions are determined with a multi-objective genetic algorithm based on the coupled solid-fluid mechanical model for six different shear thickening rheologies. The accuracy of the simplified flow model is verified by means of steady-state and transient CFD simulations for the optimal candidates. We have found that the dominating parameters of such devices are (a) the shear thickening region of the fluid rheology and (b) the gap sizes, while the piston diameters and the zero viscosity or the critical shear rate of the fluid have less effect. Based on the results, we give guidelines to design similar-length compensating devices.

Design and off-line tuning of a longitudinal driver model for EiL applications

Tightnening emission regulations and increasing powertrain complexity lead car manufacturers to rely on novel testing methods in order to frontload development. Among these, Engine-in-the-Loop, that is, the coupling of a physical internal combustion engine (ICE) on a testbed with a virtual environment, shows great promise for emission- and consumption-related tasks. In particular, this study focuses on the driver model, a simple yet crucial component of the virtual environment. A longitudinal driver model is developed in Simulink based on the PI-regulation structure and augmented with anti-windup, cycle preview, and takeoff strategy. While the PI approach is generally chosen in the literature, this study details the implementation of the added functions, and proposes a method for the gains of the model to be tuned in simulation by considering engine dynamics, and using several performance indicators. The virtual driver is then tested in a complete EiL setup simulating an electric hybrid driveline and shows satisfactory cycle-following and overall behavior on a WLTC. Robustness of the tuning method is also studied by varying vehicle parameters on the EiL bench.

Investigation of Performance and Emission Parameters of Hydroxygen (HHO)-Enriched Diesel Fuel with Water Injection in the Compression Ignition Engine

The development of engine technologies and research on combustion processes are focused on finding new generation CI engines with simple control of the combustion process while efficiently maintaining desirable engine performance and meeting emission regulations. This comprehensive study on the relatively low hydrogen energy fraction (0.65–1.80%), supplied by onboard water electrolysers and on water injection, was performed on the performance and emission parameters of the CI engine. The article presents results of both experiment and simulation about the effect of hydroxygen and water injection on the combustion process, auto-ignition delay, combustion intensity, the temperature of the mixture and engine performance at BMEP of 0.2 MPa, 0.4 MPa, 0.6 MPa, and 0.8 MPa at a speed of 1900 rpm. For the first part, the test engine operated with diesel fuel with 3.5 L/min of hydroxygen gas supplied with an external mixture formation. The HHO has an effect on the combustion process at all range of BMEP. A decrease in BTE and increase in BSFC were noticed during tests. The peak pressure and the rate of heat release decreased, but the NOx decreased as well. The second part of experiment was performed with the injection of a substantial amount of water, 8.4–17.4 kg/h (140–290 cm3/min), and the same amount of hydroxygen. The injection of water further decreased the NOx; therefore, HHO and WI can be used to meet emission regulations. A simulation of the combustion process was carried out with the AVL BOOST sub-program BURN. The AVL BOOST simulation provided a detailed view of the in-cylinder pressure, pressure-rise, combustion intensity shape parameter and SOC.

One-Dimensional Analysis of Double Annular Combustor for Reducing Harmful Emissions

The number of aircraft flights worldwide has increased steadily since the introduction of air transportation to the public. Accordingly, environmental issues caused by the exhaust gases of aircraft engines have emerged. In particular, international organizations have crafted emission regulations since gases exhausted during takeoff and landing have been identified as the direct cause of air pollution near airports. Nitrogen oxides (NOx) produced at high combustion temperatures and carbon monoxide (CO) due to incomplete combustion affect the performance of the combustion chamber. Therefore, annular combustors comprising two annular zones have been developed to reduce the emissions of these two substances, which occur under different conditions. Parameters that should be considered when modifying a conventional single annular (SAC) to a double annular combustor (DAC) are discussed herein. In this paper, an optimization algorithm for obtaining the main design parameters of the DAC is presented to minimize NOx and CO emissions and an operation solution for reducing carbon monoxide emission is identified. A thermodynamic model of a high-bypass turbofan engine (PS-90A) is used to establish the inlet and outlet conditions of the combustor. Analysis results show that NOx emissions can be effectively reduced by adjusting the design parameters and CO emissions can be significantly decreased by partially turning off the fuel supply based on the engine cycle.

Analysis of Driving Dynamics Considering Driving Resistances in On-Road Driving

Internal combustion engine emissions are a serious worldwide problem. To combat this, emission regulations have become stricter with the goal of reducing the proportion of transportation emissions in global air pollution. In addition, the European Commission passed the real driving emissions–light-duty vehicles (RDE-LDV) regulation that evaluates vehicle emissions by driving on real roads. The RDE test is significantly dependent on driving conditions such as traffic or drivers. Thus, the RDE regulation has the means to evaluate driving dynamics such as the vehicle speed per acceleration (v·apos) and the relative positive acceleration (RPA) to determine whether the driving during these tests is normal or abnormal. However, this is not an appropriate way to assess the driving dynamics because the v⋅apos and the RPA do not represent engine load, which is directly related to exhaust emissions. Therefore, in the present study, new driving dynamic variables are proposed. These variables use engine acceleration calculated from wheel force instead of the acceleration calculated from the vehicle speed, so they are proportional to the engine load. In addition, a variable of driving dynamics during braking is calculated using the negative wheel force. This variable can be used to improve the accuracy of the emission assessment by analyzing the braking pattern.