Modern combustion-electric PowerPack drive system design solutions for a hybrid two-unit rail vehicle

The article presents an innovative solution of a two-unit rail vehicle system for passanger transport with a dual-drive, diesel engine and electric motor. The vehicle was designed as a combination of two units, one dedicated to each of the two drive systems, where one unit provides electric drive while the other a combustion engine. The selection of engine and drive components was presented along with the aftertreatment systems used in the design. The provided solution was created in response to the dynamic needs of rail vehicle operators in the European Union who aim to reduce exhaust emissions without compomising the reach of the existing rail networks.

Ammonia Slip Estimation Based on ASC Control-Oriented Modelling And OBD NOx Sensor Cross-Sensitivity Analysis

The incoming emission regulations for internal combustion engines are gradually introducing new pollutant species, which requires greater complexity of the exhaust gas aftertreatment systems concerning layout, control and diagnostics. This is the case of ammonia, which is already regulated in heavy-duty vehicles and to be included in the emissions standards applied to passenger cars. The ammonia is injected into the exhaust gas through urea injections for NOx abatement in selective catalytic reduction (SCR) systems and can be also generated in other aftertreatment systems as three-way catalysts. However, ammonia slip may require removal on a dedicated catalyst called ammonia slip catalyst (ASC). The set consisting of the urea injection system, SCR and ASC requires control and on-board diagnostic tools to ensure high NOx conversion efficiency and minimization of the ammonia slip under real driving conditions. These tasks are based on the use of NOx sensors ZrO2 pumping cell-based, which present as a drawback high cross-sensitivity to ammonia. Consequently, the presence of this species can affect the measurement of NOx and compromise SCR-ASC control strategies. In the present work, a methodology to predict ammonia and NOx tailpipe emissions is proposed. For this purpose, a control-oriented ASC model was developed to use its ammonia slip prediction to determine the cross-sensitivity correction of the NOx sensor placed downstream of the ASC. The model is based on a simplified solution of the transport equations of the species involved in the main ASC reactions. The ammonia slip model was calibrated using steady- and quasi-steady-state tests performed in a Euro 6c diesel engine. Finally, the performance of the proposed methodology to predict NOx and ammonia emissions was evaluated against experimental data corresponding to Worldwide harmonized Light vehicles Test Cycles (WLTC) applying different urea dosing strategies.

A Review of Hybrid Electric Architectures in Construction, Handling and Agriculture Machines

Recent regulations on pollutant emissions have pushed working machines manufacturers towards research and development efforts to meet the strict limits imposed. For a long time, the use of gas aftertreatment systems have been the most widely accepted solution to reduce the amount of pollutants produced per unit of work done. However, lower emissions limits lead to larger systems and consequently higher difficulties in vehicle integration. Thus, alternative solutions have been studied in the last years to solve the emissions problem using wisely the on-board space. Hybrid electric technologies represent a valuable alternative in this direction. In this work, a review of the current state of the art in the adoption of hybrid and electric technologies on working vehicles is proposed. Due to the high amount of application fields and concepts for special applications, the analysis focused on the three major fields which however includes most of the working machines: Construction, Handling and Agriculture. This work highlights how the requirements of each specific field, strongly affects the design of an optimal hybrid electric architectures.

The Influence of Cycle-to-Cycle Hydrocarbon Emissions On Cyclic NO:NO2 Ratio from a HSDI Diesel Engine

Knowledge of the NO:NO2 ratio emitted from a diesel engine is particularly important for ensuring the highest performance of SCR NOx aftertreatment systems. As real driving emissions from vehicles increase in importance, the need to understand the NO:NO2 ratio emitted from a diesel engine during transient operation similarly increases. In this study, crank-angle resolved NO and NO2 measurements using fast response CLD (for NO) and a new fast LIF instrument (for NO2) have been taken from a single cylinder diesel engine at three different speed and load points including a point with and without EGR. In addition, crank-angle resolved unburned hydrocarbon (UHC) measurements have been taken simultaneously using a fast FID. A variation of the NO:NO2 ratio through the engine's exhaust stroke is also observed indicative of in-cylinder stratification of NO and NO2. A new link between the NO:NO2 ratio and the UHC emissions from an individual engine cycle is observed - the results show that where there are higher levels of UHC emissions in the first part of the exhaust stroke (blowdown), the proportion of NO2 emitted from that cycle is increased. This effect is observed and analysed across all test points and with and without EGR. The performance of the new fast LIF analyser has also been evaluated, in comparison with the previous state-of-the-art and standard "slow" emissions measurement apparatus showing a reduction in the noise of the measurement by an order of magnitude.