Labor Heizungs- und Klimatechnik
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- Activated carbon (2)
- CARBON (2)
- Corrosion (2)
- DRIVEN (2)
- ETHANOL ADSORPTION (2)
- Ethanol (2)
- waste heat (2)
- ADSORBENTS (1)
- ADSORPTION REFRIGERATOR (1)
- Adsorption refrigeration (1)
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Hydrogen storage based on the repeated reduction and oxidation (redox) reactions of iron oxide/iron composites represents a promising technology. This work is dedicated to studying the influence of the amount of water added during the pelletizing process on the cycle stability and structure of iron oxide pellets. The storage composites were prepared from iron oxide (Fe2O3) and 10 wt.-% support material (cement) with different amounts of water (18 and 33 wt.-%) in a laboratory-scale pelletizing disk. To evaluate the cycle stability of the composites, the kinetics of the redox reactions were experimentally measured at 800 ∘
C in an atmosphere of 50% N2 and 50% H2 (reduction) or 50% steam (oxidation), respectively. Moreover, the structure of the pellets was analyzed by micro-computed tomography scans. It turned out that pellets with higher water contents attained faster kinetics and a higher cycle stability. The sample with the least water content (18 wt.-%) needed about 26 min and 19 min to reach a conversion rate of 80% during the reduction and oxidation reactions of the sixth redox cycle, respectively. In contrast, the sample with the highest water content (33 wt.-%) could achieve the same conversion rate after 18 min (reduction) and 13 min (oxidation) during the ninth redox cycle.
Dokumentation, Vorbereitungen und
Ergebnisse der zweijährigen Messperiode vom 01.11.2014 bis 31.10.2016
Ausgehend von Konzeption und Planungsdaten für das Effizienzhaus Plus der Firma Karl Bachl GmbH & Co. KG in Deggendorf‐Natternberg berichten wir über die Ergebnisse des energetischen Monitorings über den Zeitraum von zwei Messjahren vom 01.11.2014 bis 31.10.2016. Die OTH Regensburg wurde mit der wissenschaftlichen Begleitforschung dieses Modellprojekts im Rahmen des Zukunft‐Bau‐Netzwerks Effizienzhaus Plus1 beauftragt.
Das Gebäude wird vorwiegend solarthermisch beheizt, ergänzt durch eine elektrische Nachheizung. Neben Solarkollektoren befinden sich auch PV‐Module auf dem Dach, deren Erträge den Jahresstrombedarf bilan‐ ziell decken. Durch Einsatz eines Batteriespeichers kann der Anteil des selbst genutzten PV‐Stroms erhöht werden.
Die Gesamtbilanz des ersten Jahres zeigt, dass das Gebäude primär‐ und endenergetisch die Anforderungen an den Effizienzhaus Plus Standard erfüllt.
Wir stellen die Energieflüsse, Gewinne und Verbräuche, sowie die Wirkungsgrade, den solaren und elektrischen Deckungsgrad und den Autarkiegrad des Gebäudes im Detail vor und diskutieren den Einfluss des elektrischen Batteriespeichers sowie der thermischen Verluste aus dem Pufferspeicher.
Verbesserungspotentiale werden in der Beseitigung von haustechnischen Fehlfunktionen und in einer stärkeren Dämmung des Pufferspeichers gesehen. Dieser ist zudem für den beabsichtigten Zweck nach den Erkenntnissen aus den empirischen Messungen zu groß dimensioniert, wodurch sich für künftige Projekte ein Einsparungspotential ergibt.
The effect of both heat and mass transfer characteristic lengths (HTCL, MTCL) of two different adsorber plate heat exchangers (APHE), for application in an adsorption chiller, on the adsorption and desorption kinetics is investigated. Three representative test frames (TF1-TF3) are prepared to examine small-scale adsorbent samples of the microporous silica gel (Siogel of Oker-Chemie, Germany) applying the volumetric large-temperature-jump methodology at different operating conditions. Based on the obtained kinetic data, an analytical model has been developed to predict the specific cooling power (SCP) and the coefficient of performance (COP) of a single-bed adsorption chiller comprising the studied APHEs. It turned out that, within the tested range of HTCL and MTCL, it can be concluded that, the adsorption kinetics are mainly influenced by the MTCL, while the desorption kinetics are dominated by the HTCL of the adsorbent domain. Applying Siogel as loose pellets inside a newly introduced APHE results in of 423.3 and 182.7 W⋅kg−1, at the evaporator temperatures of 15 °C and 5 °C, respectively. Herein, the condenser and adsorber-end temperatures amount to 30 °C and the desorption-end temperature to 90 °C. The corresponding s amount to 0.50 and 0.40, respectively, which represent quite promising results for further design optimizations.
In the present paper design, realization and testing of a novel small scale adsorption refrigerator prototype based on activated carbon/ethanol working pair is described. Firstly, experimental activity has been carried out for identification of the best performing activated carbon available on the market, through the evaluation of the achievable thermodynamic performance both under air conditioning and refrigeration conditions. Once identified the best performing activated carbon, the design of the adsorber was developed by experimental dynamic performance analysis, carried out by means of the Gravimetric-Large Temperature Jump (G-LTJ) apparatus available at CNR ITAE lab. Finally, the whole 0.5 kW refrigerator prototype was designed and built. First experimental results both under reference air conditioning and refrigeration cycles have been reported, to check the achievable performance. High Specific Cooling Powers (SCPs), 95 W/kg and 50 W/kg, for air conditioning and refrigeration respectively, were obtained, while the COP ranged between 0.09 and 0.11, thus showing an improvement of the current state of the art. (C) 2016 Elsevier Ltd. All rights reserved.
In the present work, an experimental study on a lab-scale adsorption refrigerator, based on activated carbon/ethanol working pair is reported. An extensive testing campaign has been carried out at the CNR ITAE laboratory, with multiple aims. First, the performance has been evaluated in terms of both COP and Specific Cooling Power (SCP), under different boundary conditions, including both air conditioning and refrigeration applications. Attractive SCPs, up to 180 W/kg and 70 W/kg for air conditioning and refrigeration, respectively, were measured. Under the same conditions, COP between 0.17 and 0.08 were obtained. In addition, different management strategies, namely, heat recovery between adsorbers and re-allocation of phase durations, were evaluated to identify their influence on the system. Both strategies confirmed the possibility of increasing COP and SCP up to 40% and 25%, respectively. Moreover, a design analysis based on the experimental results has been carried out, to suggest possible improvements of the system. The obtained results demonstrated the possibility of employing a non-toxic refrigerant like ethanol reaching performance comparable with other harmful refrigerants like ammonia and methanol. (C) 2017 Elsevier Ltd. All rights reserved.