TY - JOUR A1 - Gelner, Alexander A1 - Eitel, Michael B. M. A1 - Mikhail, Maria A1 - Olbrich, Lorenz Frank A1 - Pierri, Alessia A1 - Borgato, Alessia A1 - Landgraf, Tobias T1 - An exploration on the effectiveness of face-to-face and virtual meetings in educational projects dealing with impact innovation JF - CERN IdeaSquare Journal of Experimental Innovation N2 - Which is the most effective format for meetings in a project dealing with impact innovation? This paper presents the results of a survey amongst 42 business school students experiencing face-to-face or virtual meetings during their MBA classes. Qualitative interviews and a personality test clarify the results. A significant majority of students rated face-to-face meetings as more effective for the ideation phase of the projects, which contains predominantly brainstorming. The results show no clear tendency for the phase of research and preparation for the final assignment as well as for a written report. For presentations, the majority considers face-to-face meetings as more effective. UR - https://doi.org/10.23726/cij.2023.1415 Y1 - 2023 UR - https://doi.org/10.23726/cij.2023.1415 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-57662 SN - 2413-9505 VL - 7 IS - 1 SP - 12 EP - 17 PB - CERN CY - Genf ER - TY - JOUR A1 - Zepf, Andreas A1 - Gelner, Alexander A1 - Härtl, Martin A1 - Jaensch, Malte T1 - 3D-CFD-Based optimization of piston Geometry, injector nozzle Design, and injection strategy for the alternative diesel fuel Oxymethylene ether (OME) JF - Fuel N2 - Oxymethylene ethers (OMEs) represent a promising alternative to conventional diesel fuels, offering carbon–neutral mobility and soot-free combustion due to the absence of carbon–carbon bonds. This prevents the soot-NOx trade-off. Moreover, an OME-adapted and optimized combustion process offers the opportunity to improve engine efficiency while simultaneously reducing NOx emissions, thus addressing the existing efficiency-NOx trade-off. Realizing this potential necessitates tailoring the mixture preparation and combustion process to the unique characteristics of OME. This study explores the optimization of piston geometry, injector nozzle design, and injection strategies to leverage OME’s unique properties for improved engine performance. Using 3D-CFD simulations with the CONVERGE software, key parameters such as nozzle diameter, spray angle, and piston bowl shape are analyzed for their impact on efficiency and emissions. The results highlight that wider piston bowl geometries enhance indicated efficiency, while larger nozzle diameters improve combustion efficiency due to reduced combustion durations. Smaller spray angles effectively lower NOx emissions but introduce challenges such as piston wetting and localized temperature peaks. The study also confirms that pilot injection does not benefit OME operation, simplifying injection system requirements. These findings underline the need for tailored engine designs to fully exploit OME’s potential as a sustainable fuel. The proposed configurations pave the way for further experimental validation and practical implementation in internal combustion engines, contributing to the global transition toward low-carbon transport systems. UR - https://doi.org/10.1016/j.fuel.2025.136995 Y1 - 2025 UR - https://doi.org/10.1016/j.fuel.2025.136995 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-63407 SN - 1873-7153 VL - 406 IS - Part B PB - Elsevier CY - New York ER - TY - JOUR A1 - Armbruster, Felina A1 - Gelner, Alexander A1 - Zepf, Andreas A1 - Prager, Maximilian A1 - Härtl, Martin A1 - Jaensch, Malte T1 - Investigations on particle emissions of large-bore engines powered by natural gas and hydrogen JF - Environmental Science: Advances N2 - TIn an effort to mitigate the impact of climate change, e.g., by reducing the emission of greenhouse gases, hydrogen is becoming an increasingly attractive alternative energy source, replacing conventional long-chain hydrocarbon fuels in the energy and transport sector. While there is a shift in individual transport towards battery-electric applications, the maritime and energy production sectors rely on a high energy density and time- and location-independent availability of the energy carrier. Therefore, large-bore engines powered by renewable fuels have the potential to shift the industry towards a climate-neutral operation. Besides the emission of greenhouse gases, internal combustion engines are known for emitting pollutant emissions, harming human health and the environment. Research on particle emissions of natural gas and hydrogen engines has mainly focused on automotive and heavy-duty applications. Hence, this study investigates particle emissions of a large-bore single-cylinder research engine powered by hydrogen, compared to natural gas, for the first time. Investigations on particles with a diameter as low as 10 nm showed particle numbers of 104 to 105 # cm−3, unexpectedly achieving slightly higher particle numbers in hydrogen than in natural gas operations. This is due to particles from lubricant oil and a stronger fuel interaction with the liner oil film in hydrogen operation, demonstrated within a 3D-CFD simulation. The concentrations are still lower by several orders of magnitude than in long-chain hydrocarbon fuel operations of identical engines. An extended emissions analysis based on the gaseous components THC, CO, and CO2 shows the negligible carbonaceous emissions induced by these oil-based particles. UR - https://doi.org/10.1039/D4VA00200H Y1 - 2024 UR - https://doi.org/10.1039/D4VA00200H UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-50189 SN - 2754-7000 VL - 3 IS - 11 SP - 1524 EP - 1536 PB - RSC CY - London ER - TY - JOUR A1 - Gelner, Alexander A1 - Rothe, Dieter A1 - Kykal, Carsten A1 - Irwin, Martin A1 - Sommer, Alessandro A1 - Pastoetter, Christian A1 - Härtl, Martin A1 - Jaensch, Malte A1 - Wachtmeister, Georg T1 - Particle emissions of a heavy-duty engine fueled with polyoxymethylene dimethyl ethers (OME) JF - Environmental Science: Atmospheres N2 - 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. UR - https://doi.org/10.1039/D1EA00084E Y1 - 2022 UR - https://doi.org/10.1039/D1EA00084E UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-54799 SN - 2634-3606 VL - 2 IS - 2 SP - 291 EP - 304 PB - RSC CY - Cambridge ER - TY - JOUR A1 - Gelner, Alexander A1 - Pang, Genny A. A1 - Weber, Markus A1 - Haisch, Christoph A1 - Beck, Harald A. A1 - Pastoetter, Christian A1 - Härtl, Martin A1 - Jaensch, Malte A1 - Wachtmeister, Georg T1 - Gaseous emissions of a heavy-duty engine fueled with polyoxymethylene dimethyl ethers (OME) in transient cold-start operation and methods for after-treatment system heating JF - Environmental Science: Advances N2 - Polyoxymethylene dimethyl ethers (OME) are promising e-fuels for diesel engines, combining carbon-neutral production and low-emission engine operation by virtue of soot-free combustion. The emissions of diesel engines fueled with OME and in blends with diesel have been studied extensively using single-cylinder research engines under laboratory conditions. Emissions from a series engine using an exhaust after-treatment system (ATS) – especially in cold-start operation – are largely unexplored. This study presents investigations conducted using a heavy-duty engine with ATS in a transient driving cycle including cold-start operation. Measurements from a Fourier transform infrared spectrometer (FT-IR) showed that formaldehyde and formic acid form the largest proportion of the monitored tailpipe exhaust emissions due to incomplete combustion in cold-start operation, as long as the catalysts are below their light-off temperature. Non-target screening using a mass spectrometer for online characterization of both gaseous and aerosol exhaust revealed that unburned OME accounts for the majority of gaseous emissions of heavy species in raw exhaust, independent of cold- or hot-start. The ATS removes OME in the exhaust equally in the cold and the hot run. Additionally, this study presents results with specific measures taken for ATS heating such as electrical heating and fuel dosing – demonstrating that electrical heating in combination with an early start of fuel dosing reduces nitrogen oxide (NOx) emissions in the transient driving cycle by 64.9%, but at the cost of an increase in formaldehyde emission of 58.3%. A later start of fuel dosing avoids this increase and reduces NOx emissions by 61.8%. UR - https://doi.org/10.1039/D2VA00080F Y1 - 2022 UR - https://doi.org/10.1039/D2VA00080F UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-54800 SN - 2754-7000 VL - 1 IS - 4 SP - 470 EP - 482 PB - RSC CY - London ER -