<p dir="ltr">This thesis presents a comprehensive dynamic modeling and model calibration framework and experimental validations for air-source heat pumps under cycling of frosting and reverse-cycle defrosting operations. </p>

The study is conducted to determine practical modelling and simulation techniques to perform dynamic stability and performance analysis on a 3 Degrees of freedom aircraft model using a Modelica-based commercial tool called Modelon Impact. This study is based on a conceptual aircraft model where in-depth details about the aircraft configuration are unknown and the aim is to determine a suitable model that can capture the longitudinal dynamics and aerodynamic constraints of the aircraft during the conceptual design phase. Requirements include short execution time, easy model development, and minimal data requirements. Therefore, this thesis aims at developing plant and control architectures in  Modelon Impact which can be utilized for the rapid development of aircraft concepts with adequate fidelity in a longitudinal mission-based tracking environment. In a conceptual aircraft design environment, to identify a suitable methodology that mitigates the limitations of a traditional feedback controller, two methodologies are considered for comparison: Sequential DAE resolution (SDR) and Dynamic inversion (DI) control which is discussed from an object-oriented aircraft model. The advantages and shortcomings of each of the models discussed above are compared by conducting several experiments in increasing order of longitudinal mission complexity, and the most appropriate model among the two for a conceptual stage of aircraft design development is ascertained. The two methodologies discussed are compared for their level of complexity, code structure, readability, and ease of usability.

Concentrating Solar Power (CSP) is one of the most promising renewable energybased electricity generation technologies to deal with the increasing demand of power consumption and environmental sustainability. With the aim of achieving the 2020 SunShot cost target for CSP of 60 USD/MWh, the United States Department of Energy presented, in May 2018, the Gen3 CSP initiative. In particular, the CSP Gen3 Liquid-Phase Pathway proposes to design a CSP system adopting liquid sodium as Heat Transfer Fluid (HTF) in the receiver, advanced high-temperature molten chloride salt as storage fluid and supercritical CO2 (sCO2) Brayton cycle as power cycle. Within this framework, the aim of this master thesis was to design the sodium-chloride salt Heat Exchanger (HX) by developing both a heat exchanger model and a sodiumsalt-sCO2 system model. To pursue these purposes, a completely new Modelica-based HX model was developed and added to the SolarTherm library. Furthermore, as an extension of earlier models, the sodium-salt-sCO2 CSP system (NaSaltsCO2System) was implemented in SolarTherm, by incorporating the HX model and linking it with other new and existing component models. As for the HX, a general model was developed for shell and tube heat exchangers, based on the TEMA guidelines, with the possibility of being customized in terms of media adopted, constraints, boundary conditions, and correlations. The model performs an optimization in order to select the internal geometry configuration that optimizes a user-defined objective-function. By employing the implemented HX model in the NaSaltsCO2System, the sodium-salt heat exchanger was designed aiming at minimizing the Levelized Cost of Electricity (LCOE), providing a complete geometry description, and an estimation of the performances and costs. The resulting NaSaltsCO2System model was found to be robust and able to perform annual simulations that allowed to estimate the energy performances of the CSP plant, as well as the LCOE. Considering the sodium-salt-sCO2 CSP system characterized by a receiver capacity of 543 MWth, 12 hours of Thermal Energy Storage (TES), and a 100 MWe power block, the LCOE resulted equal to 72.66 USD/MWh. The sodium-salt HX design that minimizes the LCOE resulted in a single-shell/single tube pass configuration, with vertical alignment, characterized by an overall height of 15 m, and a shell diameter of 1.8 m. It represents the 3.2% of the total capital cost of the plant. An interesting system-level optimization was then carried out on the combined receiver-heat exchanger block. It regarded the variation of the Log Mean Temperature Difference (LMTD) of the HX and highlighted the possibility to drop the LCOE down to 68.54 USD/MWh. The techno-economic investigations and the sensitivity analysis showed the flexibility and robustness of the HX model, as well as the importance of the NaSaltsCO2System. The latter lays the groundwork to explore potential improvements of this new generation of CSP systems, which can play a fundamental role in the future global energy mix. / Termisk solkraft (CSP) är en av de mest lovande elproduktionsteknologierna baserade på förnybar energi. Den kan bidra till hanteringen av den ökande efterfrågan på energi och miljömässig hållbarhet. I syfte att uppnå 2020 SunShot-kostnadsmålet för CSP på 60 USD/MWh presenterade USA:s energidepartement Gen3 CSPinitiativet. I synnerhet föreslår CSP Gen Liquid-Phase Pathway att utforma ett CSPsystem som använder flytande natrium som värmeöverföringsvätska i mottagaren, smält kloridsalt med hög temperatur som lagringsvätska, samt superkritisk CO2 (sCO2) Brayton-cykel som kraftcykel. Syftet för detta examensarbete var att utforma natriumkloridsaltets primära värmeväxlare genom att utveckla både en värmeväxlarmodell (HX) modell och en natriumsalt-sCO2-systemmodell. För att fullfölja dessa syften utvecklades HX-modellen först, sedan implementerades natriumsalt-sCO2 CSP-systemet NaSaltsCO2System. Båda verktygen utvecklades med hjälp av Modelica som programmeringsspråk. De finns nu tillgängliga i det öppna SolarTherm-biblioteket. När det gäller HX utvecklades en allmän modell för skal- och rörvärmeväxlare med möjligheten att anpassas när det gäller antagna medium, begränsningar, gränsvillkor och korrelationer. Dessutom utförde modellen en optimering för att välja den interna geometri-konfigurationen som optimerar en användardefinierad objektiv-funktion. Genom att använda den implementerade HX-modellen i NaSaltsCO2System designades natriumsalt-värmeväxlaren, vilket gav en fullständig konfiguration-beskrivning och en uppskattning av prestanda och kostnader. Den utvecklade NaSaltsCO2System-modellen visade sig vara robust och kapabel till att utföra simuleringar på årsbasis. Detta gjorde det möjligt att uppskatta CSP-anläggningens energiprestanda samt LCOE. Det utvecklade natriumsalt-sCO2 CSP-systemet som känneteckna des av en mottagarkapacitet på 543 MWth, 12 timmars TES och ett 100 MWe power block, resulterade i en LCOE på 72.66 USD/MWh. Natrium-salt HX-konstruktionen som minimerade LCOE resulterade i en enskalig/enkel rörpassningskonfiguration, med vertikal inriktning, kännetecknad av en total höjd av 15 m och en skaldiameter på 1.8 m. Det motsvarade 3.2% av anläggningens totala kapitalkostnad. Den mest intressanta systemoptimeringen genomfördes på det kombinerade blocket bestående av mottagare och värmeväxlare. Den behandlade variationen av HX:s LMTD och framhöll möjligheten att sänka LCOE till 68.54 USD/MWh. De teknisk-ekonomiska undersökningarna och känslighetsanalysen visade flexibiliteten och robustheten i HX-modellen, liksom vikten av NaSaltsCO2Systemet. Den senare lägger grunden för att utforska potentiella förbättringar av denna nya generation av CSP-system, som kan spela en grundläggande roll i den framtida globala energimixen.

Modeling of heat transfer using Dymola. In this report a evaporator, economizer and superheater where modeled. The report describes how the models where modeled and what input was most suitable for a accurate model.

Le contexte énergétique global impose, durablement aux industriels la poursuite des efforts en matière d'efficacité énergétique nécessitant le déploiement de nouveaux procédés innovants éco-efficaces. Une meilleure gestion de l'énergie permet l'amélioration de l'efficacité énergétique globale des procédés ainsi que la réduction des émissions de CO2. Dans ces conditions, la récupération et la valorisation de la chaleur perdue apparait comme un potentiel pour atteindre ces objectifs. L'intégration d'une pompe à chaleur à haute température permet une valorisation de pertes calorifiques en satisfaisant des besoins de chauffage à haute température (>130°C) qui apparaissent simultanément dans certains procédés (distillation, séchage...). Malheureusement, les pompes à chaleur répondant à ces besoins industriels sont indisponibles actuellement. C'est dans ce contexte que s'inscrit la présente étude qui a permis le développement et la mise en place d'une pompe à chaleur à haute température utilisant l'eau comme fluide frigorigène. Les verrous techniques et technologiques limitant la faisabilité d'une telle machine ont été levés en concevant une nouvelle architecture de PAC et en développant deux types de compresseur : un compresseur bi-vis adapté et un compresseur centrifuge bi-étagé à paliers magnétiques. La mise en place de cette PAC munie du compresseur bi-vis est présentée. Un modèle dynamique de cette pompe à chaleur est développé avec Modelica en tenant compte de la présence de gaz incondensables dans la machine. Des modèles détaillés des compresseurs sont développés en fonction de leurs caractéristiques géométriques. Une étude expérimentale de la phase de démarrage est présentée montrant le processus de purge des incondensables et l'évolution de certains paramètres de la pompe à chaleur. Ces résultats expérimentaux ont été confrontés à des simulations numériques. Plusieurs modes de fonctionnement de la machine de récupération des pertes calorifiques sont simulés numériquement et analysés énergétiquement ainsi qu'exergétiquement. Le modèle de pompe à chaleur a enfin été intégré à un modèle de colonne à distiller montrant les économies d'énergie globales et les avantages environnementaux obtenus.

Le transport maritime fait face à trois défis majeurs : le dérèglement climatique, l'augmentation du cours du baril et le durcissement des normes internationales en termes de pollution et d'émission de CO2. Ce triple challenge peut être relevé en réduisant la consommation de fioul. L'efficacité énergétique des navires est déjà très bonne en comparaison des autres moyens de transport mais elle peut et doit encore progresser. Il existe à cet effet de multiples solutions techniques et opérationnelles. Mais évaluer leur impact réel sur les économies finales n'est pas toujours chose aisée étant donnée la complexité des navires. Une première approche globale de modélisation énergétique du navire tente de répondre à cette problématique. Basée sur le premier principe de la thermodynamique, cette approche a permis de modéliser un paquebot. La consommation de fioul et les émissions associées ont été calculées avec un niveau d'exactitude satisfaisant. Le modèle s'est de plus montré très utile dans la comparaison d'alternatives de conception, illustrant ainsi sa capacité à évaluer les solutions d'économie d'énergie. Une deuxième approche vient compléter la première. Basée cette fois-ci sur le second principe et notamment sur le concept d'exergie, cette approche propose une description plus détaillée et physique du navire. Elle permet d'évaluer précisément les gains d'énergie possibles et en particulier la part convertible en travail mécanique. Cette approche novatrice a nécessité le développement de nouveaux modèles et notamment un nouveau modèle de moteur diesel basé sur l'approche moyenne et qui permet de calculer la balance thermique complète et ce sur tout le champ moteur.

This work is in the introduction focused on the introduction of technologies for electrical energy storage, their description and capturing the main advantages and disadvantages. After this capture follows comparison of the various technologies in terms of efficiency , discharge time and the price for1 kWh . Following section focuses on electrochemical model VRB batteries , which describes the equations describing the behavior of a battery depending on the chemical an electrical properties . In the penultimate chapter, I introduced the language of object- oriented modeling language Modelica and the most common programs based on it, including a short introduction for modeling in MathModelica. The last part deals with the modeling of specific VRB battery, which we have at the faculty.

<p>In the United States, buildings are responsible for almost 40% of the country’s total energy consumption and 38% of the total greenhouse gas emissions. Researchers are constantly seeking sustainable and efficient energy generation solutions for buildings as society continues to cope with the intensifying energy crisis and environmental deterioration. Thermoelectric technology is one such solution that potentially can lead to significant energy recovery and conversion between waste or excess thermal energy and electrical energy. One promising application is integrating thermoelectric materials into the building envelope (TBE) for power generation and building heating and cooling without transporting energy among subsystems and refrigerant use. TBE can combine structural support and thermal storage with power generation and thermal-activated cooling and heating, thereby contributing to sustainable living and energy. </p> <p>TBE technology is still in its early development stages. This dissertation aimed to develop a fundamental understanding of the characteristics, behaviors, operation, and control of TBE systems as energy-efficient measures for thermal energy harvesting and thermal comfort regulation and to address the significant research gaps concerning high-conversion efficiency materials and optimal module configuration as well as system deployment related to real-world applications. Accordingly, this dissertation focused on the following three key objectives: (1) development and characterization of new thermoelectric composite materials; (2) identification of optimal designs and controls of TBE and established mathematical models for performance simulation; and (3) quantification of the energy-saving benefits of TBE. </p> <p>The following five aspects specifically were investigated:</p> <p>(1)<em> Material development and characterization</em>. New thermoelectric cement composites were developed with cement and various additives, material concentrations, and fabrication methods in the laboratory. Their thermoelectric properties (e.g., Seebeck coefficient, thermal conductivity, electrical conductivity, power factor, and the figure of merit) were measured simultaneously and characterized at 300–350 K.</p> <p>(2)<em> Module evaluation.</em> Commercially available thermoelectric modules (TEMs) were assessed using well-designed test apparatus in both the heat pumping and power generation modes. The test results validated the numerical model, which assisted with performance comparison and material selection between cement-based and commercial TEMs for the TBE prototype.</p> <p>(3)<em> Prototype assessment. </em>A convective TBE prototype and a radiant TBE prototype were designed, assembled, and evaluated in a pair of controlled testing chambers. The TBE’s surface temperature, thermal capacity, and COP were assessed under summer and winter conditions. </p> <p>(4)<em> Prototype modeling. </em>The first-principle-based numerical models of both the convective and radiant TBE prototypes were developed in Modelica. The modeling results indicated good agreement with the experimental data. The verified models were used to study the impacts of the design parameters and operating conditions on the heat pumping performance of TBE.</p> <p>(5)<em> System simulation. </em>A TBE building system model was established by integrating the TBE prototype model within a building’s heat balance model, considering the building construction, climate condition, power control, etc. Its seasonal performance under various climate conditions was studied to identify the potential optimal operation and energy savings. </p> <p>This dissertation confirmed several key findings in the areas of material development, system design and operation, and energy savings. The TBE achieved higher efficiency with a heat pump for heating than for cooling generally. The TBE heating system performed better than a conventional electric heater (efficiency assumed at 0.9). The measures that improved TBE heating efficiency were enhancing the material’s thermoelectric properties, optimizing the geometry and number of TEMs, and improving the boundary heat transfer of TEMs. </p> <p>This dissertation concluded that the TBE system is a promising alternative to conventional heating systems in buildings. Furthermore, the knowledge gained will strengthen the understanding of thermoelectrics in the building domain and guide further development in TBE, as well as facilitate the operation of net-zero energy and carbon-neutral buildings. </p>

Die Entwicklung mechanischer Antriebskonzepte für nichtlineare Bewegungsaufgaben stellt bis heute ein komplexes und domänenübergreifendes Fachgebiet des Maschinenbaus dar. Auf dem Gebiet der ebenen Koppelgetriebe gibt es dabei seit vielen Jahren Versuche, die optimale Lösung für eine Aufgabe unter Berücksichtigung kinetischer Kenngrößen zu finden. Die vorliegende Arbeit stellt eine Methodik vor, die sowohl den klassischen Verfahren der Getriebetechnik als auch den Ansätzen der Mechanik zum Ausgleich der Massenwirkungen im Getriebe gerecht wird. Der entwickelte Ansatz des modulbasierten Analyse-Synthese-Parameter-Abgleiches (ASPA) erlaubt erstmals eine domänenübergreifende Simulation komplexer Antriebskonzepte auf Basis einer neuartigen modularen Synthesebibliothek. Diese lässt sich dank umfangreicher Dokumentation und der dargestellten Programmablaufpläne in beliebige Software implementieren. Die exemplarisch im Systemsimulator SimulationX implementierte Bibliothek ermöglicht somit unter anderem die Anwendung der klassischen Drei- und Vierlagensynthese im bewegten oder ruhenden Bezugssystem für Dreh- und Schubgelenkketten. Neben der Ausgabe gerundeter Getriebeabmessungen eröffnet der beschriebene Ansatz somit die Berücksichtigung kinetischer Kenngrößen wie den Pendelschwingungen in spielbehafteten Gelenken oder der Änderung der Trägheitskenngrößen während der Synthese. Weiterführend kann eine multikriterielle Optimierung der noch freien Syntheseparameter erfolgen. / Developing nonlinear transmitting planar coupler linkages represents a domain spanning area in mechanical engineering. In recent years many efforts have been made to determine the optimal planar linkage regarding kinetic characteristics. This thesis introduces a method linking classical synthesis procedures with mechanical approaches for a dynamically balanced mechanism. For the first time, the module based analysis-synthesis-parameter-adjustment (ASPA) allows for a domain spanning simulation of complex drive assemblies based on a novel modular synthesis library. Due to an extensive documentation and detailed program flow charts it is possible to implement the library in arbitrary software environments. The exemplarily implemented library in SimulationX allows to apply the classical three- and four-position synthesis within a steady or moving reference frame of revolute or prismatic joint chains. Further, the modules return rounded link dimensions. By applying this library according to ASPA it is now possible to account for kinetic boundaries such as pendulum oscillations of joints with joint clearance or the change of mass properties during the position synthesis. Thus, a multi-criteria optimization of the remaining free synthesis parameters can be applied.

This master's thesis deals with modeling of linear electrical circuits through the differential algebraical equation systems. It describes methods of numerical solving, discusses the need of algebraical conversions and possibility of minimalization through the use of parasitic components. In addition, it involves the design and implementation of extension of available simulation tool.