Solar thermal component activation

Wall and roof components made of steel sandwich elements are firmly established in industrial and commercial construction. They are cost-effective and characterized by excellent physical properties. Here, hybrid approaches from heating- and cooling ceiling construction were examined for the solar thermal activation of sandwich elements. Besides the implementation of the solar components, the connection to and the optimization of the system technology was focused. In addition, alternative piping materials were investigated numerically and experimentally. The performance as well as the static and thermo-hydraulic behavior of the new active components were simulatively and experimentally examined, and the economic viability of the variants was also checked. With the newly developed solar sandwich elements, an overall energy concept was developed with connection variants to the building services system, control and storage technology. Steel sandwich elements with mineral fiber core are well suited for the hidden integration of component parts such as pipe registers and heat conducting plates. The functionality of the component has been proven, the implementation of heat exchanger leads to considerable heat gains. In combination with a brine-to-water heat pump system, the solar panel can provide for a more sustainable operation and a significant size reduction of the geothermal source

The Fundamental Diagram of Pedestrian Movement Revisited

The empirical relation between density and velocity of pedestrian movement is not completely analyzed, particularly with regard to the `microscopic' causes which determine the relation at medium and high densities. The simplest system for the investigation of this dependency is the normal movement of pedestrians along a line (single-file movement). This article presents experimental results for this system under laboratory conditions and discusses the following observations: The data show a linear relation between the velocity and the inverse of the density, which can be regarded as the required length of one pedestrian to move. Furthermore we compare the results for the single-file movement with literature data for the movement in a plane. This comparison shows an unexpected conformance between the fundamental diagrams, indicating that lateral interference has negligible influence on the velocity-density relation at the density domain $1 m^{-2}<\rho<5 m^{-2}$. In addition we test a procedure for automatic recording of pedestrian flow characteristics. We present preliminary results on measurement range and accuracy of this method.Comment: 13 pages, 9 figure

Twenty-three unsolved problems in hydrology (UPH) – a community perspective

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through on-line media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focussed on process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come

Enameled Glass Panels for Solar Thermal Building Envelopes

The paper presents a novel concept of solar thermal panel specifically intended for building integration, aiming at a higher architectural quality and at a reduction of installation costs. The panel consists of a low-emissivity enameled flat glass as solar absorber and a metallic heat exchanger, which are glued together by an adhesive layer. It features high design flexibility and can be used as roof or façade cladding in combination with common frames and profiles. We analyze the potential of the panel both as uncovered and covered collector by means of efficiency measurements on large-sized prototypes according to ISO 9806. Our results show that panels equipped with black enameled glass can achieve performance values competitive with those of commercial available products (uncovered panel: η0 = 0.75, b1 = 8.05 W/m2K, b2 = 1.64 J/m3K, bu = 0.043 s/m; covered panel: η0 = 0.74, a1 = 4.26 W/m2K, a2 = 0.013 W/m2K2). As reported by our optical measurements on small samples, colored glass can exhibit solar absorptance up to 0.93, thus representing an aesthetically appealing alternative to black panels. For its implementation, system integration, operating conditions and design aspects have to be taken into consideration

Development of an insulated glass solar thermal collector

Insulated glass solar thermal collectors result from the insertion of a solar absorber into the outer gap of a multiple glazed unit. Taking advantages from the manufacturing technology of the glass and window industry, a flexible and highly automated production as well as an easier and architecturally more appealing integration into the building envelope is expected. Ensuring long-term functionality, on the other hand, represents a very challenging development task due to high temperatures and to the thermally induced deformations of the solar absorber. The paper analyzes the behavior of this new kind of collector by means of theoretical calculations and experiments, focusing on both the performance and the reliability aspects. Efficiency measurements according to EN 12975 on prototypes with a slim design report specific values comparable to those of standard flat plate collectors (η0 = 0.78, a1 = 3.77 W/m2K, a2 = 0.011 W/m2K2 for a 50 mm thick, argon-filled prototype). Prolonged exposure to stagnation temperature and internal thermal shock-tests attest the durability of collector configurations featuring temperatureresistant components and suitable constructions, able to reduce and compensate the absorber deformation

Twenty-three unsolved problems in hydrology (UPH)–a community perspective

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through online media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focused on the process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come