•Integrated system of MCH dehydrogenation and H2 power generation is proposed.•Enhanced process integration is adopted to realize high energy efficiency.•The proposed system can realize very high ...energy efficiency of 58.9%.•Compared to Graz cycle based system, the proposed system shows excellent efficiency.
Hydrogen (H2) has been well studied for its potential use in energy storage, which is particularly related with the intermittent characteristic of renewable energy sources. However, the gas form of H2 at standard pressure and temperature (STP) poses a challenging problem in terms of storage, transportation, and low volumetric energy density. An effective and reversible method for H2 storage is chemically bonded H2 used in the toluene (C7H8)/methylcyclohexane (MCH, C7H14) cycle. This study investigates a power generation system from H2 storage in MCH, involving the dehydrogenation process and the combined cycle as a power generation process. An adequate analysis of the heat circulation was performed through an enhanced process integration (EPI) to ensure the high energy-efficiency of the proposed system. A highly endothermic reaction of dehydrogenation was supplied by utilizing the energy/heat from air-fuel combustion to ensure the effective heat recovery of the system. The proposed system was analyzed through an adjustment of the main operating parameters, namely, the GT inlet pressure, GT inlet temperature, and the condenser pressure, to observe their effects on the efficiency of the system. It was found that these parameters have a significant influence on the system performance and provide the possibility of further improvement. Under optimum conditions, the proposed system can realize a very high system efficiency of 54.6%. Moreover, the proposed system is also compared to a Graz cycle-based system, which has been reported to achieve an excellent power generation cycle from H2. This result implies that the proposed integrated system leads to a significantly higher power-generating efficiency. Numerically, the proposed system demonstrated a system efficiency of 53.7% under similar conditions as the Graz cycle based system, which achieved a system efficiency of 22.7%.
Dieser Teil des Berichts vom Umbau der Universitätsbibliothek Graz beinhaltet die Phase von der Gleichenfeier im Juli 2018 zur Eröffnung des Gebäudes im September 2019 und die nachfolgende ...Entwicklung.
One of the most promising technologies to decrease greenhouse gas emissions is carbon capture and storage (CCS). Oxy-fuel combustion, in which high-purity oxygen mixed with flue gases is used to burn ...fuels, reduces the complexity of CCS systems. Several methods have been studied for oxygen production to feed the process, where cryogenic air separation is the most mature technology. However, it is a highly energy-intensive method, which motivates the research of other alternatives such as ceramic membranes.
In order to compare the performance of both oxygen separation methods, the coupling of an oxygen production cycle based on ceramic membranes with a high-efficient power cycle, the Graz cycle, is studied. This cycle initially operates using cryogenic air separation.
The calculations of both cycles are carried out using the simulation software IPSEpro. For the membrane cycle, two cases are identified, whose main difference is the method to reduce the oxygen partial pressure on the permeate side of the membrane: vacuum generation (Case 1) and membrane sweeping (Case 2). Both cases are optimized, considering the thermodynamic conditions of the membrane operation and its effects on the energy consumption of oxygen production. Membrane cases achieve 54.08% and 55.76% of net efficiency for Case 1 and 2, respectively, being 0.61% and 2.30% points higher than the base case. Furthermore, the differences in turbomachine performances and streams variations are discussed, considering the effects of energy integration of membrane cases.
•A membrane-based oxygen production cycle is coupled with the Graz Cycle.•Two membrane cases are identified and compared with the cryogenic base case.•High membrane areas (in the order of 105–106 m2) are needed.•Thermal efficiency improvements of 0.61 to 2.30% are achieved.
Božidar Špišić was a pioneer of Croatian orthopedics. In 1908 he founded the first private orthopedic clinic in the entire South Slav region. During the First World War he organized and headed the ...first orthopedic hospital for the rehabilitation and resocialization of wounded soldiers. In the interwar period, Špišić was tasked with establishing the orthopedic clinic within the auspices of the School of Medicine, University of Zagreb. This effort in shaping and developing orthopedics in Croatia would not have been possible without his participation in a wide network of internationally renowned orthopedists. After graduating from the University of Graz in 1904, Špišić spent the next 4 years specializing in orthopedics with Hans Spitzy, Arnold Wittek, Fritz Lange and, most importantly, Adolf Lorenz. In this paper, we have reconstructed the transfer of knowledge and experiences between these prominent Austrian and German orthopedists and Božidar Špišić. We have paid special attention to the identification of those elements in Špišić's work that can be traced back to his mentor, teacher and lifelong colleague Adolf Lorenz, such as his treatment for congenital hip dislocation. We believe that the analysis of professional networks can shed additional light on the historiography of orthopedics, given that these influences did not manifest solely through the acquisition of specialized clinical knowledge but also through a profound influence on the core tenets of orthopedics as a discipline-its institutional organization and overall conservative approach.
This article compared modern hydrogen power plants over a wide range of total compression ratios while maintaining constant system output. In addition, the conventional modern new combined cycle ...power plant fueled by 100 % methane serves as a reference (comparative) variant representing the currently constructed generating units. Simulations were done using Ebsilon Professional software in the total compression ratio range of 20–50. Previous literature has mainly been based on comparing only the efficiency of GRAZ systems with a combined cycle power plant. The paper discusses a number of performance characteristics. Attention was drawn to the limitations of the currently used COT temperature and the temperature of the compressed medium. For the gas-steam power plant, hydrogen was traditionally burned in air, and in the Graz system, hydrogen was burned in pure oxygen. The structures of the analysed systems were presented and characterised, and their main computational assumptions were standardised in order to compare the systems. A common turbine cooling model was used for both systems. The methodologies for evaluating the performance of energy systems were discussed. Efficiencies, and levels of CO2 emissions per unit were compared for the studied systems. The calculations showed that for the currently used combustion outlet temperature (COT) of 1600 °C, the Graz system achived the best results. The system achieved a COT of 1600 °C for a total compression ratio of 82, which is much higher than that of the main analyses. It operated without CO2 emissions and had an efficiency of 56.21 %, considering the energy consumption of the air separation unit (ASU). For the modern new combined cycle power plant fueled by 100 % methane and for a hydrogen-fueled variant systems, the efficiencies were 53.86 % and 51.39 %, respectively. The modern gas-steam power plant had a high emission rate compared to other systems, reaching 325.17 kgCO2/MWh.
•RES require the provision of peak generation units.•Energy transition can be based on hydrogen power plants.•The zero emission Graz plant with ASU provides power generation efficiency of 56.2 %.•CO2 unit emissions for COT = 1600 °C in the CC CH4 system was 325.17 kg/MWh.•Increasing the COT in the gas turbines will translate into increased system efficiency.
Dieser Teil des Berichts vom Umbau der Universitätsbibliothek Graz beinhaltet die Phase vom Abriss des alten Gebäudes bis zur Gleichenfeier im Juli 2018.
Monitoring the changes in people’s presences in public spcaes can play a vital role in enhancing placemaking research. This study investigated Herrengasse Street in Graz, Austria, and Oxford Street ...in London, the UK, using a systematic review, real scene interpretations, and expert advice to check the casual and deductive arguments. A six-step conceptual framework was then developed to prioritize the changes brought by the size of people’s presences in the city streets, which involved the identification of the perceptual qualities, the influence of the socio-morphological characteristics, and the effect of the affective atmospheres on the street environment situations. It was found that measuring the changes in people’s presences was essential when seeking to reconstruct affective atmospheres. However, future research is needed to investigate the shape of people’s presence or absence in public spaces, with a specific focus on the effects of the lockdown and physical distancing on post-pandemic placemaking and the associated affective atmospheres.
The article discusses the Worlding SF conference that took place in Graz, Austria in December 2018. Over the course of the conference, three distinct strands of academic discussions emerged: (1) the ...criticism of science fiction as part of a multinational cultural production machinery and the discordant interests that this produces; (2) the growing intersectionality and diversity of representation in science fiction; and (3) the anthropocene as a central motif for science-fictional speculation that impacts more and more discourse in sf studies.
Die Bibliothek der Universität für Musik und darstellende Kunst Graz (KUG) hat im April 2014 ein Projekt zum Thema NS-Provenienzforschung begonnen, es ist das erste Projekt dieser Art an der KUG. Das ...Projekt beschränkt sich auf die Sondersammlung, die einen Bestand von ca. 430 Büchern und ca. 1.080 Musikdrucken und Autographen aufweist. Einen Schwerpunkt bilden die Nachlässe von zumeist steirischen Komponisten und Komponistinnen. Da die Bestände erst nach 1960 erworben wurden und die Sondersammlung sich hauptsächlich aus Nachlässen, Schenkungen und aus Ankäufen aus Antiquariaten zusammensetzt, gestaltet sich die Provenienzrecherche als schwierig. Ohne distinktive Hinweise aufden Vorbesitzer oder die Vorbesitzerin in den einzelnen Exemplaren lässt sich deshalb die ursprüngliche Herkunft nicht eindeutig klären. Dabei gilt es auch zu bedenken, dass – vor allem bei Ankäufen aus Antiquariaten – die Bücher und Noten den Besitzer oder die Besitzerin mehrfach gewechselt haben können.
Die Vorgabe des Projektes war es, den Bestand der Sondersammlung auf verdächtige Bücher und Noten zu überprüfen, geraubte Bestände zu identifizieren und an die rechtmäßigen EigentümerInnen oder deren Nachkommen zu restituieren...
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