@misc{BuergerRiebel, author = {B{\"u}rger, Patrick and Riebel, Ulrich}, title = {Electrostatic Charging and Precipitation of Nanoparticles in Technical Nitrogen: Highly Efficient Diffusion Charging by Hot Free Electrons}, series = {Jahrestreffen der ProcessNet-Fachgruppen Computational Fluid Dynamics und Gasreinigung}, journal = {Jahrestreffen der ProcessNet-Fachgruppen Computational Fluid Dynamics und Gasreinigung}, doi = {10.13140/RG.2.2.35735.11687}, pages = {1}, abstract = {Electrostatic charging and deposition of a liquid nano-aerosol was studied in dry air and in technical (3.6 \% O2) nitrogen. The experiments have shown that electronic charging of aerosols can be important in technical scale electrostatic precipitators (ESPs). Already at operation voltages just slightly above the corona onset voltage, the contribution of the free electrons to the overall current is estimated to be around 50 \%. Due to the high temperature of free electrons, diffusion charging by free electrons allows to reach exceptionally high particle charge and extremely high precipitation efficiency. A strongly simplified theoretical model was developed, which gives a good prediction of particle charge based on averaged values of particle diameter, current density, electric field strength, electron temperature and residence time. The ion mobilities were determined by fitting the current-voltage characteristics with a modified Townsend (Monrolin et al. 2018) equation and are significantly higher than the values typically used to describe diffusion charging in air. This may be ascribed to the very dry gas phase and the short average lifespan of the ions under ESP conditions, which is in the order of 1 ms. From the practical point of view, electronic charging might be relevant in a number of technical applications, including high temperature ESPs, ESP applications in dry and oxygen-free gases and pulsed corona systems. We gratefully acknowledge the financial support for this project (EFRE-StaF 23035000) by the European Fund for Regional Development. Monrolin, N., Praud, O., Plourabou{\´e}, F. 2018. Revisiting the positive DC corona discharge theory: Beyond Peek's and Townsend's law. Phys. Plasmas 25, 063503; doi: 10.1063/1.5031780.}, language = {en} } @misc{BuergerRiebel, author = {B{\"u}rger, Patrick and Riebel, Ulrich}, title = {Electrostatic charging and precipitation of nanoparticles in technical nitrogen: Highly efficient diffusion charging by hot free electrons}, series = {Journal of Aerosol Science}, journal = {Journal of Aerosol Science}, number = {141}, issn = {1879-1964}, doi = {10.1016/j.jaerosci.2019.105495}, pages = {17}, abstract = {Electrostatic charging and deposition of a liquid nano-aerosol was studied in dry air and in technical (3.6 \% O2) nitrogen. The experiments have shown that electronic charging of aerosols can be important in technical scale electrostatic precipitators (ESPs). Already at operation voltages just slightly above the corona onset voltage, the contribution of the free electrons to the overall current is estimated to be around 50 \%. Due to the high temperature of free electrons, diffusion charging by free electrons allows to reach exceptionally high particle charge and extremely high precipitation efficiency. A strongly simplified theoretical model was developed, which gives a good prediction of particle charge based on averaged values of particle diameter, current density, electric field strength, electron temperature and residence time. The ion mobilities were determined by fitting the current-voltage characteristics with a modified Townsend (Monrolin et al. 2018) equation and are significantly higher than the values typically used to describe diffusion charging in air. This may be ascribed to the very dry gas phase and the short average lifespan of the ions under ESP conditions, which is in the order of 1 ms. From the practical point of view, electronic charging might be relevant in a number of technical applications, including high temperature ESPs, ESP applications in dry and oxygen-free gases and pulsed corona systems.}, language = {en} } @misc{BacherRiebelMedinaMendezetal., author = {Bacher, Christian and Riebel, Ulrich and Medina M{\´e}ndez, Juan Ali and Schmidt, Heiko}, title = {Nutzbarmachung des elektrischen Windes zum verbesserten W{\"a}rme und Stofftransport im Elektroabscheider}, series = {ProcessNet 2020, Fachgruppe Gasreinigung}, journal = {ProcessNet 2020, Fachgruppe Gasreinigung}, pages = {1}, abstract = {Zur F{\"o}rderung einer nachhaltigeren Wertsch{\"o}pfungskette werden im Rahmen der Energiewende st{\"a}ndig neue Verfahren und Konzepte zu deren Umsetzung entwickelt. Eines dieser Konzepte befasst sich mit der Zusammenf{\"u}hrung bislang entkoppelter Prozessschritte in Gasreinigungssystemen aus der Energie- und Anlagentechnik. Aus den daraus resultierenden Einsparungen bei den Investitionskosten profitieren nicht nur die klassischen Energieerzeugeuer und Produktionsanlagen in der chemischen Industrie, sondern es werden auch neue Anreize zur dezentralen Energieeinspeisung von kleineren und mittelst{\"a}ndischen Unternehmen gesetzt. Elementarer Bestandteil dieser Gasreinigungssysteme sind h{\"a}ufig Elektroabscheider, welche weit verbreitet im Einsatz sind um Abgase von St{\"a}uben bzw. Aerosolen zu befreien, oder um staubf{\"o}rmige Wertprodukte aus Gasstr{\"o}mungen abzuscheiden. Die in Elektroabscheidern prinzipbedingt vorhandenen elektro¬¬hydro¬dyna¬mischen Str{\"o}mungen, auch als elektrischer Wind bezeichnet, sollen nun systematisch genutzt werden, um neben der Aerosolabscheidung gleichzeitig Aufgaben des W{\"a}rme- und Stoffaustauschs zu l{\"o}sen. Inhalte der Untersuchungen Zur Validierung der Machbarkeit dieser neuen Techniken wurde der Einfluss des elektrischen Windes auf die turbulente Quervermischung, anhand des verbesserten W{\"a}rme- und Stofftransports, sowie des Druckverlusts im Rohrelektroabscheider getestet. Bei den Untersuchungen wurden unterschiedliche Str{\"o}mungsgeschwindigkeiten, Elektrodengeometrien und Betriebsspannungen, sowie die Anwesenheit von Aerosol ber{\"u}cksichtigt. Ein Teil der Ergebnisse diente bereits als Validierungsgrundlage f{\"u}r numerische Simulationen mit einem neuartigen Turbulenzmodell [1]. [1] Medina, J., Schmidt, H., Riebel, U., Application of the one-dimensional turbulence model for electrohydrodynamic variable density flows, 17th European Turbulence Conference, 3-6 September 2019, Torino, Italy}, language = {de} } @misc{MedinaMendezBacherSchmidtetal., author = {Medina M{\´e}ndez, Juan Ali and Bacher, Christian and Schmidt, Heiko and Riebel, Ulrich}, title = {EHD-ODT: a stochastic turbulence model for the study of heat and mass transfer in wire-tube electrostatic precipitators}, series = {Jahrestreffen der ProcessNet-Fachgruppen Computational Fluid Dynamics und Gasreinigung}, journal = {Jahrestreffen der ProcessNet-Fachgruppen Computational Fluid Dynamics und Gasreinigung}, publisher = {DECHEMA e.V.}, pages = {2}, language = {en} } @misc{MedinaMendezSchmidtBacheretal., author = {Medina M{\´e}ndez, Juan Ali and Schmidt, Heiko and Bacher, Christian and Riebel, Ulrich}, title = {Electrohydrodynamic-enhanced internal pipe flows from a One-Dimensional Turbulence perspective}, series = {91st Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM)}, volume = {20}, journal = {91st Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM)}, number = {1}, publisher = {Wiley}, doi = {10.1002/pamm.202000132}, pages = {3}, language = {en} }