Polyoxymethylene dimethyl ethers (OME) are promising substitutes for fossil diesel fuel. Besides the possibility of closing the carbon cycle, OME also feature soot-free combustion. Although this has been demonstrated sufficiently, nanoparticle emission in OME exhaust is mainly unknown. Many studies provide information about the particle size distribution (PSD) in the exhaust of OME-fueled diesel engines, but lack a distinction between solid particles and particles of a volatile nature. This distinction is necessary in order to evaluate the potential of OME regarding Euro VI and the Euro VII exhaust gas legislation being discussed. This study investigates the PSD of fossil diesel and the OME exhaust of a heavy-duty engine with and without removal of the volatile fraction via a catalytic stripper, by means of a purpose-built sampling system based on proposals from the Particle Measurement Programme (PMP). The experiments showed that most of the nuclei mode investigated in OME operation is of a volatile nature and that the solid particle number (PN) emission is below that of Euro VI diesel operation. Moreover, the results indicate that a state-of-the-art aftertreatment system removes most of the particle emission, regardless of whether it is volatile or solid. Selective catalytic reduction using aqueous urea dosing increases solid particle emission, especially in the sub-23 nm range. However, a PMP-conformant measurement of PN₂₃ and PN₁₀ during WHSC and WHTC runs demonstrated that the PN emission of an OME-fueled engine falls below the average immission level of urban and regional background in Germany.

Cold-start emissions of the sustainable alternative diesel fuel OME are predominantly NO _x , formaldehyde, formic acid and unburned OME. Electrical heating in combination with fuel dosing is an effective method for after-treatment system heating.

Emissions of nitrogen oxides (NOx) from marine propulsion systems have gained public interest resulting in emission limits as defined by the International Maritime Organization (IMO) with IMO Tier III, especially for vessels operating in Emission Control Areas (ECA). The reduction of greenhouse gas emissions is also increasingly important for marine propulsion. Minimizing NOx while reducing climate impact calls for technologies such as the gas engine with aftertreatment systems, preferably with the ability to run on alternative fuels. A proven technology for reducing NOx in marine engines is the Selective Catalytic Reduction (SCR) aftertreatment system. It is also possible to avoid engine raw emissions by shifting the combustion process to lower temperature levels. Hydrogen is an alternative fuel with combustion properties enabling premixed operation at significantly higher air-fuel ratio than natural gas (NG) and thus, reducing raw NOx emissions. The study uses a systematic approach to compare emissions and efficiency of a lean-burn gas engine with a natural gas and a mild conversion hydrogen setup, utilizing two different strategies: combustion of NG with the assumption of an SCR catalyst and high raw NOx emissions and combustion of pure hydrogen using the NOx reduction potential of higher excess air. The scope of the study makes it possible to illustrate engine concepts for future applications in the displacement class of 4.8 L per cylinder. The highest efficiency of 45.3% was achieved with the natural gas engine and SCR. The concept with the lowest Global Warming Potential (GWP) was the hydrogen fueled engine under the prerequisite of using green hydrogen, accompanied by a reduction in efficiency of 0.6% compared to the efficiency optimum of NG with SCR. Assuming the use of gray hydrogen, the GWP was 48% and 52% higher than with NG and NG with SCR, respectively, at the efficiency-optimal operating points.

High-power silicon field-effect transistors as well as IGBTs and particularly wide-bandgap semiconductor transistors typically need negative turn-off voltage for a secure off-state, resilience to spurious turn on, and rapid transition through the saturation mode. We present a gate driver configuration with compact and very efficient supply of high-side and low-side of power transistor bridges with asymmetric bipolar control voltages without the need for costly and lossy isolated DCDC converter and only low-voltage active components. The underlying circuit consists of only a few cost-efficient components, its electrical potential is referenced to the source of the controlled semiconductor power switch, and its operation is synchronized with the gate driver out-put. It outcompetes the established use of isolated DCDC converters in gate circuits with negative voltage needs with respect to cost, size, reliability, and efficiency. Importantly, the proposed negative voltage supply allows bootstrapping without need for controllable high-voltage semiconductors for the sake of further cost reduction. We present detailed design rules of the circuit and experimentally validate circuit and control. In the automotive prototype implementation, size of the gate driver supply was reduced by 61 %, cost by 57 % and loss by more than 16%.