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Heat pumps are a key technology for decarbonizing the building sector, as they use electricity from renewable energy sources to supply heating and cooling in a resource-saving way. To reliably estimate the potential of resource conservation, it is essential to realistically predict the efficiency of energy conversion systems. However, common evaluation methods significantly neglect dynamics and the holistic evaluation of the system as a whole when determining the seasonal coefficient of performance (SCOP), which is a long-term efficiency metric for heat pumps. Predicted SCOPs are generally overestimated compared to real measured values. In addition to the energetic considerations, the demand for thermal comfort in indoor environments, which must be ensured by the energy conversion systems through space heating or cooling, is increasing nowadays. Thus, there is need to be able to evaluate energy conversion systems with respect to multi-criteria key performance indicators (KPIs) such as efficiency and comfort, which current assessment methods do not allow. This dissertation presents a novel method, which allows a holistic, multi-criteria KPI evaluation of complex energy conversion systems under realistic, dynamic boundary conditions. Applied to scenarios of heat pump systems for single-family houses, the evaluation objectives are the SCOP and the deviation of indoor temperature from its set point as representative of thermal comfort. The novel method uses the hardware-in-the-loop (HiL) concept and is referred to as “Dynamic System Evaluation” (DSE). Applying the HiL approach in this scope, the real energy system under test interacts in real-time and frequently exchanges data with dynamic simulation models of a heat transfer system and a building envelope. To apply the DSE method, the evaluation period is reduced from one year to a selection of experimental test days. In this work, we apply k-medoids clustering and demonstrate an information loss regarding the SCOP of 1.87 % due to the test time reduction from one year to four test days. Moreover, we show that the DSE method is repeatable and can be reproduced independently of the test facility and modeling language. To score the obtained results, we compare the DSE method to a pure system simulation, where the entire evaluation period of one year is assessed. In order to ensure valid system behavior of the air-to-water heat pump, which is the system under test, we perform a detailed model calibration. It turns out that the physical properties of the heat pump system can be calibrated well. In contrast, there are deviations in the operational behavior, which we can mainly ascribe to the actions of the created model of the real system controller. With respect to SCOP, the investigation leads to a relative difference of 8.43 %. The assessment of thermal comfort – primarily based on the deviations of set and actual room air temperatures – proves that the demand of space heating can be covered. In terms of the predicted mean vote (PMV) and the mean deviation of temperature residuals on each test day, the heat pump system ensures a comparable thermal comfort between the DSE method and system simulation. The mean deviation is between 2.12 K and 2.34 K. This maximum difference of 0.22 K remains in a range which is almost non-perceivable for the human body. To conclude: When a dedicated multi-criteria KPI can be defined and quantified, the reduction of the evaluation period to a selection of representative test days is verified. Hence, we recommend applying the DSE method for holistic evaluations of energy conversion systems. more...

Zeitlich dicht aufeinander folgende Produktinnovationen, der hochdynamische Markt und die Hersteller von automotiven Produkten erfordern einen eng an die Kundenbedürfnisse angepassten Entwicklungsprozess. Sicherheitsanforderungen, Zuverlässigkeitsanforderungen und Kundenerwartungen an das endgültige System und dessen Komponenten steigen stetig. Das gleichermaßen gestiegene Bewusstsein für Sicherheit und Zuverlässigkeit verlangt spezielle effektive und effiziente Analyse- und Bewertungsmethoden sicherheitskritischer Systeme. Die Bewertung von Sicherheit und Zuverlässigkeit basiert auf der Strukturbeschreibung eines Systems. Aufgrund des gestiegenen Anteils an mechatronischen Systemen im Fahrzeug, ist hier aus Entwicklungssicht eine domänenübergreifende Strukturbeschreibung notwendig, die die zuverlässigkeitstechnische Auswertung unterstützt. Der in dieser Arbeit eingeführte Systembewertungsprozess beschreibt die generelle Vorgehensweise zur Bewertung von Systemen. Des Weiteren wird eine Systemmatrix zur formalen Beschreibung der technischen, funktionalen und zuverlässigkeitstechnischen Systemzusammenhänge definiert. Diese bildet die Grundlage für die Analyse und die Evaluierung von Zuverlässigkeitsnetzen. Die Analyse der Systemmatrix erfolgt unter der Verwendung von standardisierten zuverlässigkeitstechnischen Methoden. Diese Methoden und deren Anwendung werden durch die empirische Ausfallanalyse und die Pfadimportanzanalyse erweitert. Die quantifizierten Informationen der Systemmatrix werden durch die hier eingeführten Zuverlässigkeitsnetze beschrieben und in einen Systembaukasten zusammengefasst. Dieser Baukasten erlaubt bereits quantifizierte Teilsysteme unter Beibehaltung der Bewertung innerhalb des Bewertungsprozesses wiederzuverwenden. Werden Systemanforderungen bezüglich der Qualitätsmerkmale (z. B. Zuverlässigkeit) nicht erfüllt, besteht die Möglichkeit, das System durch eine Optimierung an diese Anforderungen anzupassen. Diese Vorgehensweise wird anhand eines Entscheidungsprozesses dargestellt. Die Informationen über das System werden dem Optimierungsprozess über das Zuverlässigkeitsnetz bereitgestellt. Ergänzend werden neben der Strukturfunktion Vorschläge für die Optimierung übergeben. In Kombination mit dem Optimierungsprozess ist es möglich wichtige Konzept-Entscheidungen frühzeitig mit einer hohen Sicherheit zu treffen. Durch die Anwendung des Systembewertungsprozesses wird eine Reproduzierbarkeit der Analyseergebnisse erreicht, was im Garantiefall den Nachweis unterstützt. The automotive industry demands very rapid innovative products and evolutions of those products. Safety and reliability requirements and expectations upon the final system and components are increasing significantly. These in turn are driving the need to evolve more effective and efficient analysis techniques for safety critical systems. To realize the assessment of the system safety and reliability a structural description of a system is essential. Due to the increased use of mechatronic systems in vehicles, descriptions considering all domains of the structure and supporting technical reliability evaluation are necessary. The system evaluation process introduced in this paper describes the general procedure for the evaluation of systems. Furthermore a system matrix for the formal description of the technical, functional and reliability interrelations is introduced. This forms the basis for the analysis of the matrix and the development and evaluation of reliability networks. The analysis of the system matrix is made using standardized methods of reliability engineering. These methods and their applications are extended by the empirical failure analysis and path importance analysis. Reliability networks are used to describe the system structure and additional quantified information. They are summarized into a system construction set. This construction set allows the reuse of already quantified subsystems within the evaluation process. If system requirements are not met (e.g. reliability), it is possible to adapt and optimize the system. This procedure is illustrated using a decision-making process. All information about the system is provided to the optimization process through the reliability network. In addition to structural information proposals for optimization are provided to the process. In combination with the optimization process, important decisions at an early concept stage with a high security become possible. Through the application of the system evaluation process, reproducibility of the analytical results is achieved, which provides additional support in case of warranty verification. more...

The development time of interactive systems is decreasing rapidly while the stress of competition rises. Due to this fact the use of tools for usability evaluation is getting increasing attention. Simultaneously, the quantity of standards and guidelines which have to be regarded rises as well as the errors by their manual application. A couple of tools for automatic guideline review exist which only focus on the evaluation of location and arrangement of GUI objects (within the scope of the GUI design). Just a few tools consider the used terms (information design – wording) whereas no tool exists which is able to evaluate the use of operating controls referring to the conformity with user expectations (interaction design). In this thesis a concept for the automatic criteria oriented usability evaluation of all design areas (GUI design, wording, interaction design) by verifying the guideline conformity is developed. This concept is realised in the tool Reviser (Rapid EValuation of Interactive Systems using ExpeRt knowledge). Reviser is designed as an expert system which enables the dialog based specification of criteria in terms of rules. Designated areas of application are menu based interactive systems like cell phones or driver information systems. For the evaluation of the GUI design numerous metrics for measuring the colouring, location and arrangement of GUI objects are implemented. Furthermore the consistency of the GUI as a predictor for user satisfaction and strain is quantified. For the evaluation of the wording a comparison of used terms with a given ontology will be performed. The ontology represents the semantic relations of terms of menu based systems and has to be determined empirically. The static evaluation of the interaction design based on a formal system specification is not possible. Hence an autonomous agent is used for the first time, which is able to operate on an interactive system using a-priori knowledge. For demonstration of the tools’ ability, two driver information systems (Audi MMI, BMW iDrive) are evaluated. The systems differ in the type of user controls, the menu construction and the information presentation. Reviser was able to identify different errors of the system designs and generates numerous suggestions and remarks for the improvement of both designs. Additionally, an empirical evaluation validates almost all of the results automatically generated by Reviser. This shows that Reviser is the first tool, which has the ability to perform an automatic criteria orientated usability evaluation of interactive systems covering all design areas. more...

Im Sommer erforderliche Kühlung und Entfeuchtung der Außenluft führt zu hohem Energiebedarf konventioneller Klimaanlagen. An der TUHH wird die Kombination eines sorptionsgestützten Klimatisierungssystems mit Erdreichwärmeübertragern untersucht. Kühlung und Entfeuchtung sind dabei im Gegensatz zu konventionellen Systemen prozesstechnisch getrennt. Der elektrische Energiebedarf des untersuchten Systems lässt sich auf Hilfsenergien beschränken, so dass dieser im Vergleich zu einem System mit Kompressionskältemaschine um bis zu 74 % reduziert wird., During summer, cooling and dehumidification of outside air account for high energy demands of conventional airconditioning systems. At TUHH the combination of a desiccant assisted air-conditioning systems and borehole heat exchangers is investigated. In contrast to conventional systems, cooling and ventilation are separated within the process. The electrical energy demand of the investigated system can be reduced to auxiliary energies. In comparison with a system based on a compression chiller, the electrical energy demand is reduced by up to 74 %. more...

Auf Basis des in einem sorptionsgestützten Klimatisierungssystem vorhandenen hygroskopischen Materials ist eine Rückbefeuchtung der Zuluft möglich und der Energiebedarf wird auf Hilfsenergien reduziert. Gegenüber einem Vergleichssystem mit elektrischer isothermer Luftbefeuchtung wird der elektrische Energiebedarf des untersuchten Systems um 39 % reduziert. In Verbindung mit einer Deckenheizung im konditionierten Raum kann dabei ein hohes Niveau an thermischem Komfort gewährleistet werden., On the basis of the hygroscopic material existing in a desiccant assisted air conditioning system, re-humidifying supply air is possible and the energy demand is reduced to auxiliary energies. Compared with a system relying on electric isothermal humidification, electricity demand is reduced by 39 % for the investigated system. Using ceiling heating within the air conditioned space, a high level of thermal comfort is achieved. more...