Inst. Energietechnik

70 Items

Recent Submissions
Transient lattice contraction in the solid-to-plasma transition

Ferguson, K. R. ; Bucher, M. ; Gorkhover, Tais ; Boutet, S. ; Fukuzawa, H. ; Koglin, J. E. ; Kumagai, Y. ; Lutman, A. ; Marinelli, A. ; Messerschmidt, M. ; Nagaya, K. ; Turner, J. ; Ueda, K. ; Williams, G. J. ; Bucksbaum, P. H. ; Bostedt, C. (2016)

In condensed matter systems, strong optical excitations can induce phonon-driven processes that alter their mechanical properties. We report on a new phenomenon where a massive electronic excitation induces a collective change in the bond character that leads to transient lattice contraction. Single large van der Waals clusters were isochorically heated to a nanoplasma state with an intense 10-...

Against the Odds: The Potential of Swarm Electrification for Small Island Development States

Koepke, Mathias ; Groh, Sebastian (2016)

The paper builds on earlier observations using system complexity theory to explain the characteristics of a swarm electrification approach using existing small, distributed renewable energy generation infrastructure integrated into a grid. The concept is based on swarm intelligence where information and electricity flow between neighbors to achieve a compounding network effect, in that they are...

Towards biochar and hydrochar engineering

Dieguez-Alonso, Alba ; Funke, Axel ; Anca-Couce, Andrés ; Rombolà, Alessandro Girolamo ; Ojeda, Gerardo ; Bachmann, Jörg ; Behrendt, Frank (2018-02-27)

The impact of conversion process parameters in pyrolysis (maximum temperature, inert gas flow rate) and hydrothermal carbonization (maximum temperature, residence time and post-washing) on biochar and hydrochar properties is investigated. Pine wood (PW) and corn digestate (CD), with low and high inorganic species content respectively, are used as feedstock. CD biochars show lower H/C ratios, th...

Formation and properties of ultrathin silicon dioxide films on Ru(0001)

Klemm, Hagen William (2018)

This work presents the results of a systematic study of the preparation conditions of silica mono- and bilayers on a single crystal ruthenium (0001) surface. Each preparation step was analysed in detail with different methods. Starting with the clean Ru(0001) surface and the different oxygen terminations on it, the deposition of silicon in a low oxygen atmosphere onto an oxygen-pre-covered ruth...

Messdaten zur Absorptionskälteanlage FA2

Kühn, Annett (2018-02-09)

This contribution provides measured data of a single stage H2O/LiBr absorption chiller under partload conditions.

Präzisierungen zur Methode der charakteristischen Gleichungen

Albers, Jan (2017-11-24)

The method of characteristic equations tries to describe the part load behaviour of sorption heat converters (e.g. ab- and adsorption chillers, heat pumps and transformers) in a simple but precise manner. Nevertheless, during the application of the established method some disagreements and inaccuracies occur. For example, the analytically determined parameters of the characteristic equation do ...

Renewable electricity and backup capacities: an (un-) resolvable problem?

Praktiknjo, Aaron J. ; Erdmann, Georg (2016)

Public support for renewables has led to an unexpected investment momentum in Germany. A consequence is reduced wholesale electricity prices, the so-called merit order effect of renewables.We estimate this reduction using an econometric approach and give a quantitative overview of the financial situation of conventional generators. Our results indicate that investments in new conventional capac...

CE_Method. A MATLAB function for calculating the part load behaviour of absorption chillers and heat pumps based on (C)haracteristic (E)quations

Albers, Jan (2017-09-26)

The algorithm CE_METHOD calculates the part load behaviour of single stage absorption chillers and heat pumps explicitly as function of inlet temperatures and flow rates. For the characterisation of the chiller or heat pump the heat transfer capabilities (i.e. the UA-values) of five heat exchangers (Desorber, Evaporator, Condenser, Absorber and Solution heat exchanger) have to be known.

Assessment of household energy access: the Progress out of Energy Poverty Index (PEPI) toolkit for the microfinance sector

Realpe Carrillo, Natalia (2017)

Sustainable energy for all is one of the explicit goals of the United Nation’s post-2015 development agenda, aiming to overcome the unaffordability, unavailability and unsustainability of energy supply. It refers to the one third of the world’s population that still relies on intermittent or non-existent electricity supply, and on fossil fuels for cooking and heating; and which is mostly locate...

Techno-economic evaluation of a liquid redox process employing amino acid salts for sour natural gas treatment

Sönmez, Hatice Gülsah (2017)

Abundant sour natural gas fields have been left untapped so far due to barriers limiting their economic and environmental viability for power generation. Considering the long-term projections of global energy demand, supply and prices, sour gases could be utilized to supply the regional energy demand of gas producing countries, if there were inexpensive, reliable and environmentally friendly wa...

Thermal design and optimization of heat recovery steam generators and waste heat boilers

Rezaie Navaie, Ali (2017)

Heat recovery steam generators (HRSG) are important and critical equipment of combined cycle power plants (CCPP) that connect the gas turbine system to the steam cycle. The thermal design and the optimization of an HRSG are important for achieving safe operation, higher efficiency and reduced product cost in a combined cycle power plant. This work deals with the comprehensive optimization of the...

An investigation for energy sustainability in cement industries in Tanzania

John, John Pius (2017)

Für Zement-Produktionsprozesse stellen sich einige entscheidende Nachhaltigkeitsfragen, zum Beispiel in Zusammenhang mit ineffizientem Energie- und Rohmaterialeinsatz, Produktversorgung, Produktionskosten sowie sozialen und ökologischen Auswirkungen. Der hohe Energie- und Materialeinsatz bedingt durch Ineffizienzen in Produktionsprozessen von Zement führt wiederum zur Erschöpfung nicht-erneuerb...

Thermodynamic and economic evaluation of existing and prospective processes for liquefaction of natural gas in Malaysia

Bin Omar, Mohd Nazri (2016)

In der Energiewirtschaft wird verflüssigtes Erdgas (LNG) weltweit als umweltfreundlicher Energieträger für Klein- und Großanlagen betrachtet, wobei LNG zur Deckung des stetig wachsenden Bedarfs an elektrischem Strom geeignet ist. In der vorliegenden Arbeit werden sowohl bestehende als auch neue Prozesse zur LNG Produktion thermodynamisch und wirtschaftlich analysiert. Die analysierten Prozesse ...

Methoden und Maßnahmen zur Wirkungsgradverbesserung bei existierenden Energieumwandlungsanlagen

Boche, Lea (2016)

Im Rahmen dieser Dissertation sollen alle in einer Energieumwandlungsanlage auftretenden realen thermodynamischen Verluste erfasst werden und der Anlagenbetrieb soll, wenn möglich, verbessert werden. Schwerpunkt soll dabei die Betriebsoptimierung sein, zusätzlich wird aber auch an einem Beispiel die Umrüstung von bestehenden Kraftwerken mit neuer Technik untersucht. Diese Untersuchungen sollen ...

Operational behaviour and heat transfer in a thermosiphon desorber at sub-atmospheric pressure

Trinh, Quoc Dung (2016)

The application of thermosiphon desorbers or bubble pumps is well known from small capacity absorption refrigerators using ammonia/water as working pair. In the thermosiphon desorber the processes of refrigerant desorption and solution pumping is combined in one hermetical unit. This supersedes the necessity of a mechanical solution pump. In addition, an improved heat transfer is achieved due t...

Partielle Rücklaufkondensation von Reinstoffen und Gemischen in engen, geneigten Kanälen mit rundem und rechteckigem Querschnitt

Klahm, Thorsten (2016)

Bei der partiellen Rückflusskondensation strömt der Dampf in einem geneigten gekühlten Kanal von unten ein und das sich an den Wänden bildende Kondensat fließt ihm entgegen. Diese Art der Gegenstromkondensation bewirkt bei Gemischen eine Trennung der Komponenten. Die geringe Unterkühlung des Kondensats und der geringe Installationsaufwand wirken sich auch bei Reinstoffen positiv aus. Es kann al...

Thermo-economic evaluation, optimization and synthesis of large-scale coal-fired power plants

Wang, Ligang (2016)

A key lever to cope with the well-known issues related to today's extensive use of fossil fuels, e.g., global warming, is to design highly energy-efficient and cost-effective pulverized coal-fired power plants. Future coal-fired power plants will be with high temperature and pressure levels, multiple heat sources, multiple products, and many available technologies integrated to efficiently util...

Analytische Lösung des gekoppelten Wärme- und Stofftransportproblems bei der Absorption im laminaren Rieselfilm

Meyer, Thomas (2016)

Ziel dieser Arbeit ist, die grundlegenden Abhängigkeiten und Einflussparameter auf den gekoppelten Wärme- und Stofftransport in Absorptionswärmewandlern mit Hilfe analytischer Funktionen für technisch möglichst realistische Randbedingungen zu beschreiben. Diese analytische Lösung kann anschließend als Auslegungswerkzeug für die Wärme- und Stoffübertrager für eine möglichst effektive Ausnutzung ...

Synthesis and characterization of novel composite photoelectrodes based on chalcopyrite and silicon for the visible light-driven hydrogen and oxygen evolution

Azarpira, Anahita (2016)

In dieser Arbeit werden effiziente und stabile Mehrschicht-Halbleiter-Elektroden beschrieben, die für die beiden Halbzellenreaktionen der lichtgestützten Wasserspaltung, d.h. die Entwicklung von Wasserstoff (HER) bzw. Sauerstoff (OER), entwickelt wurden. Für die effiziente und stabile Entwicklung von Wasserstoff in sauren Elektrolyten wurden neuartige Photokathoden entwickelt, die hochqualita...

CO2 absorption rate improvement of an amino acid salt solvent with an inorganic promoter

Andrés Kuettel, Diego (2016)

This thesis studies the improvement of the CO2 absorption rate of an amino acid salt solvent with an inorganic promoter. A screening study was carried out to select the most suitable promoter regarding toxicity, absorption enhancement performance and cost. The benefit of the promoted solvent is further quantified in a laboratory mini plant and in a pilot plant that is retrofitted to a coal powe...