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Dissertation
Simulation-based optimization of solar thermal systems
(2018)
In this PhD thesis application of numerical methods to simulation-based optimization of solar thermal systems both in the planning process and in operation is investigated. The optimization process starting from definition of a target function and specification of optimization parameters, moving forward with application of an optimization algorithm and ending up by sensitivity analysis at the found optimum, is described in detail. A hybrid genetic CHC – binary search algorithm is proposed and applied. As a combination ...
Aufsatz
Characterization of polyamide 6.10 composites incorporated with microcrystalline cellulose fiber: Effects of fiber loading and impact modifier
(2018-08-14)
Microcrystalline cellulose (MCC) fiber‐reinforced polyamide 6.10 (PA) composites were prepared in the presence of an impact modifier (IM), exxelor VA1803 (VA), by melt compounding process. Fiber loading was considered from 20 to 30 wt.%, whereas IM was varied from 2.0 to 5.0 wt.%. Composites were characterized by tensile test, impact test, dynamic thermal mechanical analysis (DTMA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X‐ray diffraction (XRD). Composites’ fractured surfaces ...
Aufsatz
Evaluation of a Stratified Tank based Heat Recovery Loop via Dynamic Simulation
(2018)
Prerequisite for hot water recovery in the dairy and beverage industry is the use of heat storage, such as stratified tanks. Total Site Heat Integration enables the targeting of heat recovery potential, the concrete identification of suitable sinks and source profiles and the dimensioning of intermediate circuits and storages. For a cost and energy efficient storage, the aim to maintain stratification by suitable thermocline control management. Dynamic simulation enables a reliable estimation of energy savings and ...
Aufsatz
Dimensioning of Heat Pump Systems Based on Pinch Analysis and Energy Monitoring Data
(2018)
In this paper, typical process chains of metal processing/gear manufacturing are examined according to the pinch method with regard to their potential for heat recovery and their suitability for heat pump applications. The focus is on machine tools and parts washing machines as fluctuating heat sources and sinks. Heat sources at a low temperature level, such as the cooling of machine tools, are becoming increasingly important in contrast to conventional fossil waste heat sources due to the electrification of energy ...
Aufsatz
Sektorkopplung Prozesswärme / Strom in der deutschen Industrie
(2018)
Sektorkopplung bedeutet die Verbindung des Elektrizitäts- mit dem Wärme- und Mobilitätssektor. Während der Ausbau der erneuerbaren Energien (EE) im Strombereich erhebliche Fortschritte, bis zu einem Anteil von über 30 %, erzielt hat, ist im Wärme- (ca. 13 %) und Mobilitätssektor (ca. 5,1 %) der Anteil in den letzten zehn Jahren fast konstant geblieben. Die Elektrifizierung dieser Anwendungsbereiche soll den Anteil an erneuerbarer Energie erhöhen und somit zu einer Reduzierung von Treibhausgasen beitragen. Abbildung ...
Dissertation
Ergonomieassistenz
(2018-12-18)
Die Dissertation entwickelt und evaluiert Assistenzkonzepte in den Modalitäten visuell, auditiv und taktil zur Rückmeldung unergonomischen Verhaltens. Aufbauend auf den theoretischen Grundlagen der Assistenzsysteme, der Wahrnehmungsmodalitäten, der menschlichen Informationsverarbeitung und der adäquaten Assistenz erfolgte die Entwicklung der Assistenzkonzepte. Zur Anwendung kamen eine Augmented-Reality-Brille mit symbolischen Darstellungen in der visuellen Modalität, Kopfhörer mit Auditory Icons für den auditiven ...
Aufsatz
Effect of Post-Process Machining on Surface Properties of Additively Manufactured H13 Tool Steel
(2018-08-28)
Der Werkzeugstahl AISI H13 zeichnet sich durch einen hohen Verschleißwiderstand und eine gute Temperaturwechselbeständigkeit aus. Hauptanwendungsbereiche des H13 sind Druckguss- und Schmiedewerkzeuge. Die Verarbeitung von H13 durch additive Fertigungsverfahren, wie z. B. dem selektiven Laserschmelzen (selective laser melting, SLM), eröffnet neue Gestaltungsmöglichkeiten, wie z. B. die Integration interner Kühlkanäle, die es erlauben, das Einsatzverhalten der Werkzeuge zu verbessern. Aufgrund hoher Oberflächenrauheiten ...
Aufsatz
Martensite aging in ⟨001⟩ oriented Co₄₉ Ni₂₁ Ga₃₀ single crystals in tension
(2018-03-22)
Co–Ni–Ga high-temperature shape memory alloys (HT-SMAs) are well-known candidate materials for damping applications at elevated temperatures. Recent studies showed that upon heat treatment in stress-induced martensite under compressive loads transformation temperatures can be increased significantly, qualifying Co–Ni–Ga for HT-actuation. The increase in transformation temperatures is related to a change in chemical order recently validated via neutron diffraction experiments. Since SMAs show distinct tension–compression ...
Aufsatz
Design of novel materials for additive manufacturing - Isotropic microstructure and high defect tolerance
(2018-01-22)
Electron Beam Melting (EBM) is a powder-bed additive manufacturing technology enabling the production of complex metallic parts with generally good mechanical properties. However, the performance of powder-bed based additively manufactured materials is governed by multiple factors that are difficult to control. Alloys that solidify in cubic crystal structures are usually affected by strong anisotropy due to the formation of columnar grains of preferred orientation. Moreover, processing induced defects and porosity ...
Aufsatz
Innovative Materials for Novel Concepts for Internal Heat Exchangers
(2018-07-27)
Internal heat exchangers are often employed in solar thermal applications as well as in many other applications that involve heat, and, for the most part, consist of metallic materials (copper, stainless steel). Corrugated stainless steel tubes are easy to assemble, and are commonly used in various storage geometries. In order to significantly reduce costs, alternative materials, such as plastics, can function as excellent substitutes. Alternative heat exchangers for the following examinations using various materials ...