Multiscale Modelling for Automotive Exhaust-Gas Aftertreatment – From the Quantum Chemistry to the Engineering Level

Gegenstand der vorliegenden Arbeit ist die theoretische Untersuchung eines neuartigen Abgas-Nachbehandlungssystemes unter Verwendung eines Multiskalen-Modellierungsansatzes. Prozesse vom Nanobereich (chemische Reaktionen) bis zum Makrobereich (zeitabhängige Umsätze im katalytischen Einzelkanal) wurden durch verschiedene Modellierungstechniken beschrieben. Diese unabhängigen Techniken wurden im Rahmen eines Multiskalen-Modellierungsansatzes vereint, um ein umfassendes Modell eines Autoabgas-Katalysators zu erreichen. Das untersuchte Rhodium-basierte Abgaskatalysator-System reduziert giftige Stickoxide (NOx, x = 1,2) selektiv zu Stickstoff (N2) in einem Sauerstoff-reichen Abgas, in welchem kurzzeitig (0,1 s – 5 s) reduzierende Bedingungen generiert werden. Experimentelle Untersuchungen von Stickoxiden und Sauerstoff auf gestuften und nieder-indizierten Rhodium-Oberflächen weisen darauf hin, dass diese Oberflächen Stickoxide nicht zersetzen können, da sie umgehend Sauerstoff-vergiftet sind. Um ein genaueres Verständnis der relevanten Oberflächenprozesse zu erreichen, wurden Oberflächenreaktionen sowie Oberflächenmobilitäten mittels quantenchemischer Dichtefunktional (DFT)-Berechnungen untersucht. Es wurde gezeigt, dass die vorherrschende Oberflächenfacette auf Katalysatorpartikeln, die (111)-Oberfläche, relativ inaktiv bzgl. der NO-Zersetzung ist. Die Oberfläche wird zusätzlich durch die Präsenz einer Sauerstoff- Vorbelegung deaktiviert. Des Weiteren wurde gezeigt, dass Sauerstoff sich anfänglich sehr schnell auf Rhodium(111) zersetzt, während dieser Prozess selbsthemmend ist; die Aktivierungsenergie steigt mit steigender Sauerstoffbedeckung. Die Vermutung, dass die Deaktivierung in beiden Fällen (NO und O2) auf die dem Rhodium Elektronen-entziehende Wirkung der Sauerstoffvorbelegung zurückzuführen ist, wird durch Ladungsanalysen unterstützt. DFT-Untersuchungen von monoatomaren Stufen, dem häufigsten Defekt auf Katalysatorpartikeln, zeigten, dass die NO-Zersetzung hier wesentlich wahrscheinlicher ist, während der Prozess ebenfalls durch Sauerstoffvorbelegung deaktiviert wird. Es wurde aufgezeigt, dass, obwohl elektronische Effekte die Reaktionswahrscheinlichkeit beeinflussen, sterische Effekte einflussreicher sind. Das qualitative Wissen, welches aus diesen DFT-Studien gewonnen wurde, war die Basis von zeitabhängigen Simulationen der reaktiven Strömung in Autoabgaskatalysatoren mittels DETCHEMTRANSIENT. DETCHEMTRANSIENT ist ein Modul von DETCHEM (O. Deutschmann et al.), welches als Teil der vorliegenden Arbeit entwickelt wurde. Es simuliert das instationäre Verhalten von reaktiven Strömungen mittels eines hierarchischen Modellierungsansatzes. Zeitabhängige Umsätze simuliert durch DETCHEMTRANSIENT, basierend auf Elementarreaktions-Mechanismen, welche durch DFT-Berechnungen optimiert wurden (s.o.), konnten experimentell bestimmte Umsatzkurven erfolgreich reproduzieren. Die vorliegende Arbeit ist ein wichtiger Schritt zu einer detaillierten Multiskalen- Modellierung von Autoabgaskatalysatoren. In einem umfassenden Ansatz müssen Prozesse auf den relevanten Skalen vom Mikroskopischen zum Makroskopischen (von der Quantenchemie zum Strömungsverhalten) beschrieben werden. Im Speziellen konnten Erkenntnisse aus der Quantenchemie dazu beitragen, Prozesse auf höheren Zeit- und Längenskalen zu verstehen

Energy, Transport, & the Environment: Addressing the Sustainable Mobility Paradigm

Sustainable mobility is a highly complex problem as it is affected by the interactions between socio-economic, environmental, technological and political issues. Energy, Transport, & the Environment: Addressing the Sustainable Mobility Paradigm brings together leading figures from business, academia and governments to address the challenges and opportunities involved in working towards sustainable mobility. Key thinkers and decision makers approach topics and debates including:   ·         energy security and resource scarcity ·         greenhouse gas and pollutant emissions ·         urban planning, transport systems and their management ·         governance and finance of transformation ·         the threats of terrorism and climate change to our transport systems.   Introduced by a preface from U.S. Secretary Steven Chu and an outline by the editors, Dr Oliver Inderwildi and Sir David King, Energy, Transport, & the Environment is divided into six sections. These sections address and explore the challenges and opportunities for energy supply, road transport, urban mobility, aviation, sea and rail, as well as finance and economics in transport. Possible solutions, ranging from alternative fuels to advanced urban planning and policy levers, will be examined in order to deepen the understanding of currently proposed solutions within the political realities of the dominating economic areas.   The result of this detailed investigation is an integrated view of sustainable transport for both people and freight, making Energy, Transport, & the Environment key reading for researchers, decision makers and policy experts across the public and private sectors

Es ist Zeit, ein Wirtschaftswunder einzuläuten

Sortir de la crise Covid par le haut, en transformant notre économie pour la rendre plus durable

A futuristic view of gas-to-liquid technology

The search for alternative fuels is relentlessly under way with 90 percent of transport fuels being oil-derived and uncertainty around depletion levels of conventional oil reserves mounting. Global vehicle ownership is forecast to reach two billion in the near future and climate change concerns, induced by anthropogenic greenhouse gas (GHG) emissions, expected to rise. The central challenge involves the transformation of our oil dependent transport industry, as we face the so-called input problem of dwindling conventional crude oil reserves as well as the so-called output problem of increasing GHG emissions. Liquid fuels derived from gas, coal or unconventional oil sources may be able to offset the input problem of diminishing oil supplies, but will inevitably exacerbate the output problem of rising GHG emissions. Biofuels can be a viable substitute for fossil fuels, most notably when produced in a sustainable manner and from feedstock that is not in direct competition with food or animal feed. The transition towards advanced biofuels may contribute towards a low carbon, sustainable fuel mix, but is unlikely to be sufficient to meet the current energy demand of our global transport system. Recently, the interest in synthetic fuel production from unconventional resources has been revived through the rise in crude oil prices. Global production from unconventional sources has been projected to increase by 2030 to 7.4 million barrels per day or 10 percent of global conventional oil supply. The industry’s expectation illustrates that there are other factors at play aside from the rise in global petrol prices, which will facilitate the rapid introduction of synthetic fuels into the market

Fuel taxes, fuel economy of vehicles and costs of conserved energy: the case of the European Union

This chapter is an overview of the changes in real-world fuel economy in key countries and of recent developments in fuel taxes imposed on all fuels across the EU-Member States. Coal and gas are undertaxed but diesel and gasoline are overtaxed; however, fuel economy is directly affected by fuel taxes (prices) and not by taxes on coal. Standards on fuel economy can be interpreted as taxes on fuel and both standards and fuel taxes can be triggers for investment in alternative energy technology. Costs of conserved energy show that hybrid trucks are cost-effective to buy for freight transport operators so long as fuel costs are high. Trends in the cost of conserved energy are likely to favour investment in fuel saving technologies so long as fuel and oil prices remain high as is currently the case. Taxes on fossil fuels are one way to save fossil fuels and EU Governments are aware of the need to save fossil fuels and to reduce dependency on them. EU fuel taxes have led to improved fuel economy on EU roads.The full text of this book chapter is not currently available in ORA

Cyber Physical Production Systems and Their Role for Decarbonization of Industry

Industry is the economic sector with the highest contribution to global Greenhouse Gas Emissions (GHG) and therewith plays a major for future decarbonization. The question arises whether cyber physical production systems (CPPS) as one core element of the digital transformation of industry can contribute here. To derive the most promising fields of action and investigate the role of CPPS a holistic perspective on the industry sector is necessary. Besides energy efficiency also fostering energy transition towards renewable sources as well as material efficiency turn out to be important leverages. Major CPPS based contributions can be expected through innovative, advanced control approaches—especially for complex production situations with changing products and diverse influencing factors. But also in other areas at least indirect contributions through CPPS can be expected, e.g. for identification of best practice technologies, to align energy demand and renewable energy supply or to support material efficiency-related improvements. Altogether, CPPS based potential for industry is estimated in a range of 15–25%

The status of conventional world oil reserves--Hype or cause for concern?

The status of world oil reserves is a contentious issue, polarised between advocates of peak oil who believe production will soon decline, and major oil companies that say there is enough oil to last for decades. In reality, much of the disagreement can be resolved through clear definition of the grade, type, and reporting framework used to estimate oil reserve volumes. While there is certainly vast amounts of fossil fuel resources left in the ground, the volume of oil that can be commercially exploited at prices the global economy has become accustomed to is limited and will soon decline. The result is that oil may soon shift from a demand-led market to a supply constrained market. The capacity to meet the services provided by future liquid fuel demand is contingent upon the rapid and immediate diversification of the liquid fuel mix, the transition to alternative energy carriers where appropriate, and demand side measures such as behavioural change and adaptation. The successful transition to a poly-fuel economy will also be judged on the adequate mitigation of environmental and social costs.Liquid fuels Peak oil Conventional oil