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Even under consideration of the increasing dynamics of measures to reduce CO2 in the transport sector and the resulting, now visible changes in the development and registration of new passenger cars (electrification), it is anticipated that vehicle drives containing an internal combustion engine will continue to have significant market shares in the medium to long term. It is assumed that a significant proportion of these cars will be hybrid vehicles in the future. As a result, in order to implement future requirements for improved air pollution control (Post EU6/Zero Impact) and CO2 reduction, consideration of these aspects must be an integral part of the application and of development activities in general. At TU Darmstadt, a consistent method for the development of powertrains with regard to their relevant real-world driving emissions - the Most Relevant Testing Procedure (MRTP), was established.

To meet the targets of the European Green Deal, CO2 emissions in the transport sector must be eliminated by 2050. To achieve these goals, it is not enough just to increase the powertrain efficiency. Regeneratively produced synthetic fuels offer the opportunity to be part of the solution to these challenges, due to their high energy density and wide range of applications. One representative of synthetic diesel fuels is oxymethylene ether (OME), which, in addition to its potential regenerative production process, is characterized by an almost soot-free combustion. Previous studies have demonstrated the feasibility of OME operation in a series engine. However, due to the limited amount of fuel that can be injected into the combustion chamber by series components, the potential in terms of efficiency could not be exploited.

To comply with the ambitious CO2 targets of the European Union, greenhouse gas emissions from the transport sector should be eliminated by 2050. Incremental powertrain improvement and electrification are only a part of the solution and need to be supplemented by carbon-neutral fuels. Due to the high technology readiness level, biofuels offer a short-term decarbonization measure. The high process energy demand for transesterification or hydrotreating however, hinders the well-to-wheel CO2 reduction potential of current market biodiesels. An often-raised, economically and energetically feasible alternative is to use unprocessed oils with viscosity and cold-properties improvers instead. The present work investigates the suitability of one such biofuel (PlantanolTM) for advanced common rail engines operating in a partially premixed compression ignition mode. Preliminary investigations are carried out on a Euro VIb light-duty car engine.

The Single Cylinder Research Engine (SCRE) at the Institute of Internal Combustion Engines and Powertrain Systems is equipped with a variable valve train that allows to switch between regular intake valve lift and early intake valve closing (Miller). On the exhaust side, a secondary valve lift on each valve is possible with adjustable back pressure and thus the possibility of realising internal EGR. In combination with alternative fuels, even if they are Drop-In capable as HVO, properties differ and can influence the emission and efficiency behaviour. The investigations of this paper are focusing on regenerative Drop-In fuel (HVO), fossil fuel (B7), and an oxygenate (OME), that needs adaptions at the engine control unit, but offers further emission potential. By commissioning a 2-stage boost system, it is possible to fully equalize the air mass in Miller mode compared to the normal valve lift.

Previous studies have shown that dosing AdBlue into the exhaust system of diesel engines to reduce nitrogen oxides can lead to an increase in the number of particles (PN). In addition to the influencing factors of exhaust gas temperature, exhaust gas mass flow and dosing quantity, the dosed medium itself (AdBlue) is not considered as a possible influence due to its regulation in ISO standard 22241. However, as the standard specifies limit value ranges for the individual regulated properties and components for newly sold AdBlue, in reality there is still some margin in the composition. This paper investigates the particle number increase due to AdBlue dosing using several CPCs. The increase in PN is determined by measuring the number of particles after DPF and thus directly before dosing as well as tailpipe. Several AdBlue products from different sources and countries are measured and their composition is also analyzed with regard to the limit values regulated in the standard.