Analysis of a gas-driven absorption heat pumping system used for heating and domestic hot water preparation

Part of: Thermally driven heat pumps for heating and cooling. – Ed.: Annett Kühn – Berlin: Universitätsverlag der TU Berlin, 2013 ISBN 978-3-7983-2686-6 (print) ISBN 978-3-7983-2596-8 (online) urn:nbn:de:kobv:83-opus4-39458 [http://nbn-resolving.de/urn:nbn:de:kobv:83-opus4-39458]In the building sector the use of thermally driven heat pumps can contribute substantially to energy conservation and the reduction of end-use energy. Within the IEA HPP Annex 34 a medium size absorption heat pump application installed in a storehouse in Graz has been monitored over a period of one year. The system consists of two directly natural gas-driven ground source ammonia/water absorption heat pumps (each with ca. 40 kW heating capacity). Via a buffer storage space heating of an office building and a storage depot as well as domestic hot water preparation is provided. During the monitoring period the system showed reliable operation and high energy performance. Based on the lower heating value of the natural gas the seasonal performance of the year 2010 was 1.54 which is approx. 60% higher compared to a condensing gas boiler with a seasonal performance of 96%. However, also room for improvements has been detected, especially at start/stop operation for domestic hot water preparation in summer

"Wer a sagt, der muß nicht b sagen."

Die Arbeit nimmt eine politikwissenschaftliche Lesart ausgewählter Stücke Bertolt Brechts vor. Eingangs wird mit Hilfe der poststrukturalistischen Theorie von Gilles Deleuze, Félix Guattari und Jacques Rancière ein politischer Kunstbegriff hergeleitet, der dann auf Brecht angewendet wird. Den Maschinenbegriff von Deleuze und Guattari übernehmend wird in einem weiteren Schritt dargestellt, an welche Maschine die Brechtische literarische Maschine angeschlossen werden muss, damit sie in ihrer radikalen Gesellschaftskritik auch heute noch subversiv funktioniert. Schließlich wird die Analyse darstellen, dass Brecht in seinem materialistischen Theater davon abgeht, starre Persönlichkeiten zu zeichnen, seine Protagonisten und Protagonistinnen stellt er, ebenso wie die gesellschaftlichen Verhältnisse, durchwegs als veränderbar dar. Diese Veränderungen laufen nicht von einem fixen Zustand in einen anderen ab, sondern die These lautet, dass es sich hierbei um das von Deleuze und Guattari so beschriebene Minoritär-Werden handelt, das Aufspüren von Fluchtlinien aus dem kapitalistischen System. Die Figuren Brechts verändern sich meist dadurch, dass sie mit den gesellschaftlichen Ausbeutungsverhältnissen kapitalistischer Systeme in Berührung kommen. Die Analyse wird herausstreichen, in welche Richtungen dieses Werden in den ausgewählten Stücken stattfindet und was der Zweck des Werdens ist

The formation of non-condensable gases in ammonia/ water absorption heat pumps made of stainless steel - literature review and experimental investigation

Part of: Thermally driven heat pumps for heating and cooling. – Ed.: Annett Kühn – Berlin: Universitätsverlag der TU Berlin, 2013 ISBN 978-3-7983-2686-6 (print) ISBN 978-3-7983-2596-8 (online) urn:nbn:de:kobv:83-opus4-39458 [http://nbn-resolving.de/urn:nbn:de:kobv:83-opus4-39458]Highly efficient ammonia/water absorption heat pumping (AHP) processes (e.g. the GAX-process) require a high desorption temperature level of e.g. 200°C and above. At these conditions the formation of non-condensable gases can take place, which can be dedicated to two chemical processes: corrosion of steel and thermal decomposition of ammonia. Within a research project the possible use of stainless steel components at high temperature level has been investigated. Tests with an absorption/desorption test rig operating at temperatures up to 290°C as well as corrosion tests using autoclaves at temperatures up to 220°C have been performed. The produced non-condensable gas has been analysed using gas-phase chromatography in order to identify the responsible chemical process. The results show a large initial corrosion rate which decreases with time. This may be explained by a passivation process of the steel surface. At all tests the carbon steel (ST37) autoclaves has shown significant lower corrosion rates compared to the stainless steel components. Regarding the thermal decomposition no dissociation products has been detected up to a temperature level of 290°C

Implementation and characterization of a thermal infrared laser heterodyne radiometer based on a wavelength modulated local oscillator laser

This article presents the first implementation and the experimental characterization of a thermal infrared wavelength modulation laser heterodyne radiometer (WM-LHR) based on an external cavity quantum cascade laser. This novel WM-LHR system has demonstrated calibration-free operation, a superior signal to noise ratio and, more importantly, has opened the door for cost-efficient wide spectral range laser heterodyne radiometry in the near future.The work by P.M.-M. has been performed in the frame of the "Estancias de movilidad José Castillejo" from the Spanish Ministry of Education, Culture and Sports. P.M.-M. would also like to thank the Spanish Ministry of Economy and Competitiveness for supporting the project under the TEC2017-86271-R Grant. A.G., H. M. and B.L. acknowledge financial support received from the Austrian Research Promotion Agency FFG within the project 861581 (ATMOSENSE) of the ERA-NET Photonics program

The Impact of Exercise on Telomere Length, DNA Methylation and Metabolic Footprints

Aging as a major risk factor influences the probability of developing cancer, cardiovascular disease and diabetes, amongst others. The underlying mechanisms of disease are still not fully understood, but research suggests that delaying the aging process could ameliorate these pathologies. A key biological process in aging is cellular senescence which is associated with several stressors such as telomere shortening or enhanced DNA methylation. Telomere length as well as DNA methylation levels can be used as biological age predictors which are able to detect excessive acceleration or deceleration of aging. Analytical methods examining aging are often not suitable, expensive, time-consuming or require a high level of technical expertise. Therefore, research focusses on combining analytical methods which have the potential to simultaneously analyse epigenetic, genomic as well as metabolic changes

Ionic liquids as new absorbents for absorption chillers and heat pumps

Part of: Thermally driven heat pumps for heating and cooling. – Ed.: Annett Kühn – Berlin: Universitätsverlag der TU Berlin, 2013 ISBN 978-3-7983-2686-6 (print) ISBN 978-3-7983-2596-8 (online) urn:nbn:de:kobv:83-opus4-39458 [http://nbn-resolving.de/urn:nbn:de:kobv:83-opus4-39458]In this paper, ionic liquids are proposed as new absorbents for absorption chillers and heat pumps. The theoretical and experimental based research of Technische Universität Berlin, Bavarian Center for Applied Energy Research (ZAE Bayern) and Graz University of Technology is presented and test and simulation results are discussed. The results show the suitability and promising potential of ionic liquids as absorbents but the research organizations agree in the need of further effort in R&D

Hydrogen Sulfide Detection in the Midinfrared Using a 3D-Printed Resonant Gas Cell

A fast and reliable photoacoustic (PA) sensor for trace gas detection is reported. The sensor is based on a 3D-printed resonant cell in combination with a continuous wave mode-hop-free external cavity quantum cascade laser to rapidly acquire gas absorption data in the midinfrared range. The cell is designed so as to minimize the window PA background at a selected acoustic resonance. The goal is a resonant PA cell capable of detecting the traces of gases using wavelength modulation of the laser source and second harmonic detection. The versatility and enhancement of the limit of detection at sub-ppm levels are investigated by monitoring specific lines of hydrogen sulfide (H2S). The noise-equivalent absorption normalized to laser-beam power and detection bandwidth is 1.07 x 10-8 W cm-1 Hz-1/2 for H2S targeting the absorption line at 1247.2cm-1. These properties make the sensor suitable for various practical sensors for water quality applications.This work was supported by the Spanish Ministry of Economy and Competitiveness (grant TEC-2014-52147-R (MOSSI) and grant TEC2017-86271-R (PARAQUA)) and by the Carlos III University of Madrid (grant for the mobility of researchers)

Performance of the Intermittently Scanned Continuous Glucose Monitoring (isCGM) System during a High Oral Glucose Challenge in Adults with Type 1 Diabetes : A Prospective Secondary Outcome Analysis

To assess intermittently scanned continuous glucose monitoring (isCGM) performance for different rates of change in plasma glucose (RCPG) during glycemic challenges in type 1 diabetes (T1D). Nineteen people with T1D (7 females; age 35 ± 11 years; HbA1c 7.3 ± 0.6% (56 ± 7 mmol/mol)) performing two glycemic challenges (OGTT) were included. During OGTTs, plasma glucose was compared against sensor glucose for timepoints 0 min (pre-OGTT), +15 min, +30 min, +60 min, +120 min, +180 min, and +240 min by means of median absolute (relative) difference (MARD and MAD) and Clarke Error Grid (CEG), then was stratified for RCPG and glycemic ranges. Overall, MARD was 8.3% (4.0–14.8) during hypoglycemia level 1 18.8% (15.8–22.0), euglycemia 9.5% (4.3–15.1), hyperglycemia level 1 9.4% (4.0–17.2), and hyperglycemia level 2 7.1% (3.3–11.9). The MARD was associated with the RCPG (p < 0.0001), detailing significant differences in comparison of low, moderate, high, and very high RCPG (p = 0.014). Overall, CEG resulted in 88% (212 values) of comparison points in zone A, 12% (29 values) in zone B, and 0.4% (1 value) in zone D. The isCGM system was accurate during OGTTs. Its performance was dependent on the RCPG and showed an overestimation of the actual reference glucose during hypoglycemia

A Chlorophyll-Derived Phylloxanthobilin Is a Potent Antioxidant That Modulates Immunometabolism in Human PBMC

Phyllobilins are natural products derived from the degradation of chlorophyll, which proceeds via a common and strictly controlled pathway in higher plants. The resulting tetrapyrrolic catabolites-the phyllobilins-are ubiquitous in nature;despite their high abundance, there is still a lack of knowledge about their physiological properties. Phyllobilins are part of human nutrition and were shown to be potent antioxidants accounting with interesting physiological properties. Three different naturally occurring types of phyllobilins-a phylloleucobilin, a dioxobilin-type phylloleucobilin and a phylloxanthobilin (PxB)-were compared regarding potential antioxidative properties in a cell-free and in a cell-based antioxidant activity test system, demonstrating the strongest effect for the PxB. Moreover, the PxB was investigated for its capacity to interfere with immunoregulatory metabolic pathways of tryptophan breakdown in human blood peripheral mononuclear cells. A dose-dependent inhibition of tryptophan catabolism to kynurenine was observed, suggesting a suppressive effect on pathways of cellular immune activation. Although the exact mechanisms of immunomodulatory effects are yet unknown, these prominent bioactivities point towards health-relevant effects, which warrant further mechanistic investigations and the assessment of the in vivo extrapolatability of results. Thus, phyllobilins are a still surprisingly unexplored family of natural products that merit further investigation