This work tried to identify the influence of dosing vaporized urea solution in a selective catalytic reduction (SCR) system. In the SCR method, optimising the urea evaporation and mixing properties can significantly improve the NO_x conversion efficiency in the catalyst. It can also exert a positive effect on the uniformity of NH₃ concentration distribution across the catalyst face. The concept of an electrically evaporated urea-dosing system was investigated and it was found that urea pre-heating prior to introduction into the exhaust gas is favourable for enhancing NO_x removal under steady-state and transient engine operation. In the urea evaporating system the heating chamber was of a cylindrical tube shape and the urea vapour was introduced into the exhaust by means of a Venturi orifice. The concept urea dosing was only a custom-made solution, but proved to be superior to the regular dosing system operating in the liquid phase.

This work presents the methodology and accurate evaluation of ammonia concentration distribution measurements at the selective catalytic reduction (SCR) catalyst outlet cross-section. The uniformity of ammonia concentration is a crucial factor influencing overall SCR effectiveness, and it contributes to the necessity of employing a reliable test method. The aftertreatment system design (mainly its geometrical features) can be evaluated in detail. The ammonia concentration is measured at the SCR catalyst outlet at grid points covering from the center to the outer edges of the catalyst. Its execution requires the introduction of a probe hovering over the back face of the SCR. To obtain the expected accuracy, it is necessary to measure a sufficient number of points in a reasonable timeframe. In order to achieve that, a fully automatic sampling device was developed. Sample results are presented showing the capabilities of the created test stand and its importance for the design development and validation stages of SCR-based engine aftertreatment.

MATEC Web of Conferences, open access proceedings in Materials science, Engineering and Chemistry

This article presents the results of studies on concept solution of dosing urea in a gas phase in a selective catalytic reduction system. The idea of the concept was to heat-up and evaporate the water urea solution before introducing it into the exhaust gas stream. The aim was to enhance the processes of urea converting into ammonia, what is the target reductant for nitrogen oxides treatment. The study was conducted on a medium-duty Euro 5 diesel engine with exhaust line consisting of DOC catalyst, DPF filter and an SCR system with a changeable setup allowing to dose the urea in liquid phase (regular solution) and to dose it in a gas phase (concept solution). The main criteria was to assess the effect of physical state of urea dosed on the NOx conversion ratio in the SCR catalyst. In order to compare both urea dosing methods a special test procedure was developed which consisted of six test steps covering a wide temperature range of exhaust gas generated at steady state engine operation condition. Tests were conducted for different urea dosing quantities defined by the a equivalence ratio. Based on the obtained results, a remarkable improvement in NOx reduction was found for gas urea application in comparison to the standard liquid urea dosing. Measured results indicate a high potential to increase an efficiency of the SCR catalyst by using a gas phase urea and provide the basis for further scientific research on this type of concept.

An independently developed retrofit selective catalytic reduction (SCR) system was implemented onto a Euro 5 light duty vehicle, in order to comply with the Euro 6 nitrogen oxides (NOx) limit over the legislative laboratory cycle. The SCR catalytic converter was fitted to the existing exhaust line, downstream of the diesel oxidation catalyst and the particle filter. The urea dosing system, including NO_x sensors, was set up onboard the vehicle in order to catalytically treat the exhaust gas and effectively reduce NO_x. The urea injection strategy was managed by an external dosing control unit, while the engine calibration was not modified and remained at the Euro 5 level. The legislative tests were performed in an emission laboratory on the chassis dynamometer installed in a climatic chamber. The reference emission level of the unmodified vehicle and aftertreatment layout was established. Following SCR retrofitting process, the emission cycles were repeated, and the results obtained were compared. The SCR system effectiveness was found to be in a close correlation with exhaust gas temperature. The presented test results gave an insight into the possibility of significant NO_x reduction in modern light duty vehicles by means of usage of an add-on type of NO_x catalytic reduction system, without modifications to the engine control unit.

This paper describes a holistic development and testing approach for a battery electric vehicle (BEV) prototype based on a self-supporting body platform originating from a vehicle powered by an internal combustion engine. The topic was investigated in relation to the question of whether conversion of existing vehicle platforms is a viable approach in comparison to designing a new vehicle ab initio. The scope of work consisted of the development stage, followed by laboratory and on-road testing to verify the vehicle’s performance and driveability. The vehicle functionality targeted commercial daily use on urban routes. Based on the assumed technical requirements, the vehicle architecture was designed and components specified that included various sub-systems: electric motor powertrain, electronic control unit (ECU), high-voltage battery pack with battery management system (BMS), charging system, high and low voltage wiring harness and electrically driven auxiliary systems. Electric sub-systems were integrated into the existing vehicle on-board controller area network (CAN) bus by means of enhanced algorithms. The test methodology of the prototype electric vehicle included the vehicle range and energy consumption measurement using the EU legislative test cycle. Laboratory testing was performed at different ambient temperatures and for various characteristics of the kinetic energy recovery system. Functional and driveability testing was performed on the road, also including an assessment of overall vehicle durability. Based on the results of testing, it was determined that the final design adopted fulfilled the pre-defined criteria; benchmarking against competing solutions revealed favorable ratings in certain aspects.