Numerische Untersuchung des Wärmeübertragungsverhaltens in unterschiedlichen porösen Medien

Die Ausarbeitung befasst sich mit Simulationsstudien, die als numerisches Experiment aufgefasst werden können. Dabei werden poröse Medien als dreidimensionale Mikrostrukturmodelle aufgelöst und in einem numerischen Modell abgebildet. Basierend auf der numerischen Lösung der Navier-Stokes-Gleichungen (CFD) werden Wärmeübertragungsvorgänge und der Druckverlust bei der Durchströmung einer Porosität analysiert und Korrelationen zur vereinfachten Berechnung für die Ingenieurspraxis abgeleitet

A simulation model for the yearly energy demand of buildings with two-or-more-layered textile roofs

This document provides information and instructions for preparing a Full Paper to be included in the Proceedings of MEMBRANES 2011 Conference

Analysis of thermal evolution in textile fabrics using advanced microstructure simulation techniques

Nowadays, membrane structures represent a modern construction element to be used as roof material in modern buildings or as design element in combination with traditional architecture. Membranes are mostly used in an outdoor environment. Therefore they are exposed to wind, radiation (solar and infrared), rain and snow. Specific membranes are three-dimensional fabrics which can be used as energy absorber or as insulation of membrane roofs. The applicability as energy absorber becomes important if the three-dimensional fabrics are designed as a porous flow channel streamed by air and convectively heated up. The transferred energy may be stored in a latent heat storage system. Due to their porous structure, textile fabrics have a large heat-exchanging surface. If they are handled as homogenized porous structures, the heat transfer processes can not be described in a correct way. Therefore a microstructure model locally resolving all filaments of the three-dimensional fabrics has been formulated. By using an advanced meshing tool, a simulation technique has been developed taking into account the local heat conduction properties of the different materials. To analyse the heat transfer processes inside the three-dimensional fabrics, numerical simulations have been performed using the phase-field solver (Pace3D) of the Karlsruhe Institute of Technology and the commercial CFD-Solver StarCCM+. For a better understanding of the thermal behaviour of the fabrics, different thermal loads including thermal conduction in the microstructure (filaments) and convection by the surrounding air have been computed. The results show that the advanced simulation techniques allow to analyse the rate of conductive and convective heat transfer in three-dimensional fabrics. The results of the applied computational methods are compared

Numerische Untersuchung des Wärmeübertragungsverhaltens in unterschiedlichen porösen Medien

This presentation deals with simulation studies that will be interpreted as numerical experiments. Porous structures are modelled in three dimensions (microstructure models). Heat transfer and pressure drop of the flow through a porosity is analysed using the numerical solution of the Navier-Stokes equations (CFD). Empirical correlations for simplified calculations are presented that can be used by engineers for rough estimates and design of components with porosities like metal foam

A simulation model for the yearly energy demand of buildings with two-or-more-layered textile roofs

This document provides information and instructions for preparing a Full Paper to be included in the Proceedings of MEMBRANES 2011 Conference

Numerical investigations for an alternative textile inverter building in the area of solar power generation

Within electrical power generation by solar applications such as photovoltaics, the direct electric current is transformed into alternating current by converters. By the conversion of the current, heat is released from the electrical equipment into the building where the converters are placed. The building itself is made from concrete. Hot air (mediterranean area like Spain) sucked from the ambient by the converters into the building is the only heat sink. Water is not available. By the heat release from the inverters the indoor temperature increases up to 50 C which decreases the convective cooling effect for the inverters. Furthermore during a day cycle the concrete is heated too and the heat can not sufficiently be released from the concrete during the night. To avoid this critical thermal situation an alternative inverter building based on textile structures (membrane) has been designed. The indoor climate and energy balance of textile buildings depend highly on the optical properties of the roof’s membrane material. The heat capacity and heat resistance can be neglected (no storage effects). So the radiation becomes dominant for the thermal situation in the building during day and night. By covering the textile material, to ensure specific optical properties, the thermal impact from outside can be minimized and heat release during night to the sky becomes possible. To validate the concept, a complex three-dimensional numerical model has been set-up including heat sources inside the building. To prohibit temperature increase during the day a passive cooling system based on phase change materials [2] has been integrated into the model. Based on the numerical model a time dependent computation of the thermal behaviour of the textile building has been performed including irradiation of the sun (solar, the simulation show that the complex thermal transport mechanism for textile buildings can be well predicted by the used computing technology (CFD). Furthermore it can be demonstrated that the concept of the textile building can be a good alternative to a building made of concrete

International relations theory and the “social whole”: encounters and gaps between IR and sociology

This article explores some basic issues which arise from International Relations (IR) theory also being a form of social theory in a broader sense. Many of these issues are related to the question of a "social whole," that is, whether international relations/International Relations is one of many parts of a social whole, on what grounds it is differentiated from other parts, and whether it operates on a distinct level of social reality. We argue that these questions have been addressed in many forms of IR theory, but mostly only implicitly, and that the failure to make explicit assumptions about a social whole is probably due to the relative neglect of the subject in modern Sociology. The article argues that implicit assumptions about a social whole can be unearthed by looking at the concepts of systems, levels, and sectors, discussing debates about each of these in turn. Openly addressing IR theory as social theory, and spelling out images of a social whole, allows one to gain a sharper understanding of some of the basic analytical categories used, and to judge whether they form plausible delimitations of social reality within a wider social context

International Relations Theory and the "Social Whole": Encounters and Gaps between IR and Sociology

Albert M, Buzan B. International Relations Theory and the "Social Whole": Encounters and Gaps between IR and Sociology. International Political Sociology. 2013;7(2):117-135