Analysis of Mathematical Heat Transfer Models for free-flowing Vacuum Insulation Materials

In this poster different mathematical models describing the heat transfer mechanisms through porous materials were analyzed. They were compared respectively fitted to measured thermal conductivities of different free flowing vacuum insulation materials. Thus the models that fit the measured values the best could be determined. The aim of this work is to identify respectively develop a mathematical model that can determine the ideal mixture of different thermal insulation materials for a certain application, depending on temperature, vacuum pressure and bulk density. The abstract book of the conference, including the corresponding paper (page 113-114), can be downloaded from: http://www.ivisparis2017.org/index.php?page=abstract-submissio

Experiences with a mobile, stand-alone test facility for solar thermal collectors and systems

Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.Solar thermal technology is a booming market. As a result, a wide range of solar thermal collectors and systems are produced by numerous manufacturers all over the world. In order to assess thermal performance, manufacturing quality, safety of operation and to identify potential for further improvement, accurate testing of solar thermal collectors and thermal solar systems is required. Standardized testing procedures for solar thermal collectors are e.g. specified in the European Standard EN 12975 or the international standard ISO 9806 and for solar thermal systems in the South African Standards SANS 1370 (Mechanical tests) and SANS 6211-1 (Thermal tests) as well as in the international standards ISO 9459-2 (CSTG-method) and ISO 9495-5 (DST-method). In order to secure a growing market for solar thermal products in South Africa and its neighbouring countries, it is essential to establish a solar thermal test institute as a service provider for manufactures and suppliers in the Southern African area. For this purpose, a turn-key test facility for solar thermal collectors and systems was purchased from the German company Solarund Wärmetechnik Stuttgart (SWT). SWT is a spin-off company from the Institute for Thermodynamics and Thermal Engineering (ITW) of the University of Stuttgart. ITW has been working in the solar thermal field for more than 30 years and is operating the “Research and Test Centre for Thermal Solar Systems” (TSZ). The TZS is the largest solar test centre in Europe. Hence, very substantial experience related to testing and the construction of test facilities has been gained at ITW and SWT. The test facility for the South African Bureau of Standards (SABS) is part of a project financed by the Central Energy Fund (CEF) and the United Nations Development Program (UNDP). The facility was manufactured and instrumented by SWT based on a standard office container as a turn-key product. Before the test facility arrived from Germany, two staff members of SABS were trained for one week at SWT in Stuttgart, Germany. An additional training program took place onsite, after the test facility had been set-up and commissioned in Pretoria. The initial operation was performed together with an expert from SWT. After shipment to South Africa the test facility could be taken into operation within a few days at the South African Bureau of Standards (SABS), located in Pretoria. The South African Bureau of Standards has been working with the mobile, standalone test facility since the beginning of 2007 and has already tested several systems according to SANS 6211-1. To-date, the experiences gained with the mobile, stand-alone test facility are very good. It operates without notable problems and delivers reliable and accurate results. The paper describes the principle set-up of the test facility as well as the experience gained by SABS.vk201

Oberirdische Speicher in Segmentbauweise für Wärmeversorgungssysteme – OBSERW: Abschlussbericht zum Verbundvorhaben

Im Projekt wurde eine alternative Speicherkonstruktion im Bereich von 500 bis 6000 m3 für den Betrieb in Solar- und Fernwärmesystemen entwickelt. Ausgangspunkt bilden große Kaltwasserspeicher in Segmentbauweise. Die Bautechnologie bietet ein signifikantes Kostenreduktionspotenzial gegenüber geschweißten Flachbodentanks, konnte bisher aber nicht auf Wärmespeicher übertragen werden. Aufgrund der dünnwandigen Bauweise und der Projektziele musste eine Überarbeitung des Wandaufbaus, der Einbauten und der Peripherie erfolgen. Dieser Bericht liefert eine Beschreibung des Speicher-Systems und die Ergebnisse des Verbundvorhabens. Die Funktionsfähigkeit wurde mit einem dreistufigen Verfahren nachgewiesen. Das geplante Vorgehen mit Laborversuchen im kleinen Maßstab bis zum Test mit einem Demonstrator im Realmaßstab (100 m3) war notwendig und zielführend. Die Bearbeitung der Hauptaufgaben (z. B. Materialuntersuchungen, Konstruktion, Betrieb) erfolgte vernetzt durch die beteiligten Forschungsinstitutionen. Das grundlegende Potenzial für eine spätere Anwendung in solaren Nahwärmesystemen oder Sekundärnetzgebieten der klassischen Fernwärme sind gegeben. Vor allem im Bereich der Beladung und im Wandaufbau konnten große Verbesserungen erzielt werden. Weitere Optimierungen und die Umsetzung mit größeren Speichern stehen noch aus.In the project, an alternative construction for thermal energy stores in the range of 500 to 6000 m3 was developed for operation in solar and district heating systems. Large cold water storage tanks in segmental construction are the starting point. Their construction technology offers a significant potential for cost reduction compared to welded flat-bottom tanks, but could so far not be transferred to hot water storage tanks. Due to the new design and the project objectives, the wall structure, the internals and the periphery had to be completely revised. This report provides a description of the storage system and the results of the joint project. The functionality was proven with a three-stage procedure. The planned procedure with laboratory tests on a small scale up to the test with a demonstrator on a real scale (100 m3) was necessary and purposeful. The main tasks (e.g. material testing, design, operation) were carried out by the participating research institutions in a network. The basic potential for a later application in solar local heating systems or secondary network areas of conventional district heating is given. Significant improvements were realized, especially in regard of the charging system and the wall construction. However, further optimizations and the transfer to larger storage tanks is still pending

AMADEUS: Next generation materials and solid state devices for ultra high temperature energy storage and conversion

Starting in January 2017, AMADEUS (www.amadeus-project.eu) is the first project funded by the European Commission to research on a new generation of materials and solid state devices for ultra-high temperature energy storage and conversion. By exploring storage temperatures well beyond 1000 °C the project aims at breaking the mark of ∼ 600°C rarely exceeded by current state of the art thermal energy storage (TES) systems. AMADEUS Project, through a collaborative research between seven European partners, aims to develop a novel concept of latent heat thermal energy storage (LHTES) systems with unprecedented high energy density. One of the main objectives of the project is to create new PCMs (phase change materials) with latent heat in the range of 1000-2000 kWh/m3, an order of magnitude greater than that of typical salt-based PCMs used in concentrated solar power (CSP), along with developing advanced thermal insulation, PCM casing designs, and novel solid-state heat to power conversion technologies able to operate at temperatures in the range of 1000-2000 °C. In particular, the project will investigate Silicon-Boron alloys as PCMs and hybrid thermionic-photovoltaic (TIPV) devices for heat-to-power conversion. This paper describes the project R&D activities and the main results that have been attained during the first 6 months of work. This includes the first wettability and solubility analysis of liquid Si-B alloys, the numerical simulation of silicon phase-change and heat loss analysis through thermal insulation cover, as well as the first steps for the realization of the two main AMADEUS proof-of-concept experiments: the TIPV converter, and the full LHTES device