Refine
Has Fulltext
- no (3)
Document Type
- Doctoral Thesis (3) (remove)
Division
- Kreislaufwirtschaft (3) (remove)
The earth as we know it can only continue to exist if humanity finds a way to switch to a sustainable use of energy and resources. This work contributes to the research carried out to achieve this goal by improving the coating of adsorptive materials. These are used in heat transformation and drying processes that allow for efficient temperature and humidity control in buildings. A central component of these adsorptive coatings is the binder that acts as "glue" in the manufacturing of the coating. In this work the methods to evaluate binder performance regarding their thermal stability under the process conditions, their mechanical stability and their influence on the adsorptive properties of the coating were established. The coatings have to meet special requirements due to the thermal stresses and low pressure atmosphere they experience in these applications. A selection of silicone binders was then characterized with the established tests according to these requirements. Additionally a selection of inorganic binders was investigated because they allow for the use of high desorption temperatures and thus a high energy efficiency of the process. Out of these binders Silres® MP50E emerged as the most promising one due to very good adsorptive properties of the coating, its good temperature stability and ease of use. While some of the inorganic binders showed very good adsorptive properties and temperature stability the mechanical stability of all inorganic binders was not sufficient for their use in adsorption heat transformation technology. This is the first time that a broad selection of binders was evaluated with regards to adsorptive coatings and the results published in literature. With a suitable binder identified, the next step was to optimize the coating of the heat exchangers in order to work out how to manufacture the most efficient and powerful heat exchangers. Samples with different coating thicknesses were manufactured in small scale and full scale and their adsorption behavior was characterized. It could be shown for the first time that it is possible to increase energy efficiency by improving the mass ration of adsorber to coating and increase the delivered power at the same time. This was shown for small and full scale samples. It was shown that under the corresponding conditions the heat transfer from the coating layer to the adsorber metal substrate is the limiting step in the process. These results can now be used for the planning and construction of adsorbers. With knowledge of a suitable binder and how to coat efficient, powerful adsorbers, the coating process itself was improved to allow for industrial scale manufacturing. A central point here is the ability to control slurry rheology. Out of many rheology additives those that are suited for the application in adsorption heat transformation were identified and their influence on the slurry rheology thoroughly characterized. Additionally the process of slurry preparation could be simplified for several different adsorbents. Here it was shown that the supersonic deagglomeration step is not necessary to prepare a slurry. Extending the possible coating techniques and in addition to the dip coating process used so far, the spray coating of adsorptive coatings was established for the first time in literature. This process is widely used in the industry and allows for easier plugin into existing coating processes. For the coating of high resolution patterns a proof of concept of the screen printing process was carried out.
Elektro- und Elektronikaltgeräte zählen zu den am schnellsten wachsenden Abfallströmen in Europa. Reparatur und Wiederverwendung können durch eine Verlängerung der Produktnutzungsdauer dazu beitragen, dass weniger Abfall entsorgt werden muss und Ressourcen durch die Vermeidung von Neuproduktion eingespart werden. In der Europäischen Abfallrahmenrichtlinie (2008/98/EG) wird der "Vorbereitung zur Wiederverwendung" ein hoher Stellenwert eingeräumt; die Abfallvermeidung hat, gefolgt von der "Vorbereitung zur Wiederverwendung", eindeutig Priorität gegenüber dem Recycling. Die Abfallhierarchie verspricht zwar implizit ökologische Vorteile der "Vorbereitung zur Wiederverwendung", allerdings wurden die institutionell-ökologischen Zusammenhänge des Konzepts in der Forschungsdebatte bislang vernachlässigt. Somit sind die tatsächlichen Ressourceneinsparpotenziale der "Vorbereitung zur Wiederverwendung" noch weitgehend unerforscht. Vor diesem Hintergrund zielt das Dissertationsprojekt darauf ab, ein Verständnis dafür zu entwickeln, wie spezifische Kontexte (beispielsweise die rechtlichen Rahmenbedingungen, ökonomische oder informatorische Aspekte) die "Vorbereitung zur Wiederverwendung" von Produkten aus der Ressourcenperspektive beeinflussen. Dafür wurden die institutionell-ökologischen Zusammenhänge der "Vorbereitung zur Wiederverwendung" integrativ betrachtet, und zwar mit Fokus auf ausgewählte Geräte - Flachbildmonitore (FlaMo's), Kaffeefiltermaschinen (KaFil's), Kaffeepadmaschinen (Ka-Pad's), Lautsprecherboxen (LauS) und Waschmaschinen (WaMa's) - und im Sinne einer vergleichenden Analyse von zwei abfallstrukturell-charakteristischen Regionen - Flandern und Nordrhein-Westfalen. Die interdisziplinäre Fragestellung der Arbeit erforderte die Anwendung qualitativer Methoden für die tiefgründige Untersuchung der "Vorbereitung zur Wiederverwendung" in den verschiedenen institutionellen Systemen, aber auch quantitative Methoden im Hinblick auf die zahlenmäßige Bewertung der Ressourceneinsparpotenziale. Zentrale Datenerhebungsinstrumente waren fallbeispielbezogene öffentliche Dokumente und Webseiten, die Analyse betriebsinterner Dokumentationen, Literaturauswertungen, Stichprobenerhebungen, Beobachtungen und Experteninterviews.
With increasing world population and an unsettling resource scarcity in the back, sustainble consumption has moved to the foreground of political, economical and social discussions. One major school-of-thought is Circular Economy (CE), an approach summarizing various sustainable consumption activites under one roof. However, quantitative studies on the consumer are rare, yet crucial for a transfer from linear to circular consumption. This dissertation adds to literature by providing pioneer insights into consumer behavior in CE as an overarching concept, instead limiting research on singular subconcepts. Namely, four consumer activities are studied: recycling, upcycling, renting and sharing. In order to identify relevant insights for both academics and practitioners in CE, the research question ("what drives participation in CE?") is broken down into sub-hypotheses, which are addressed by three empirical studies. Using the SOR-Model (adaption Belk 1975) as overarching logic, the three studies deal with (1) the consumer (and their motivation) and situational stimuli (both (2) offline and (3) online). Respectively, three data sets are consulted to assess the sub-hypotheses and to identify overarching insights on how to accelerate consumer participation in CE, The research methodology employed ranges from a structured equation model (SEM), a random allocation field experiment during Fashion Week in Berlin to a discrete-choice model with best-worst scaling. The dissertation succeeds in revealing that (1) different activities in CE can be summarized in one latent variable, proving CE as a wholesome concept in consumer-related activities; that (2) Trust has a leveraging effect on participation in CE activities. Further, Trust can be enhanced offline via face-to-face interaction and online via third-party online attributes.; and that (3) experience in CE activities affects perception of online attributes, implying the need for adapted measures when dealing with CE-unexperienced consumers as compared to consumers with prior experience in CE activities.