Results 1 - 10 of 189
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[en] This report details the results of a research conducted in 1998 and 1999 and outlines a marketing deployment plan designed for businesses interested in marketing solar water heaters in the new home industry
[en] The results of numerical research on the determination of the temperature value of the internal surface of the heat-removing channel (HRC) walls of the light-absorbing heat-exchange panels (LAHPs) with the tubeon- sheet and thin-parallelepiped form of flat-plate solar water-heating collectors (FPSWHCs) are presented. The research method is based on compilation of the system of the balance equations for the light-absorbing plate (LAP) and HRCs of the LAHPs of the studied types and their designs with respect to the desired parameter. A practical example of calculation of the determination of the temperature value of the internal surface of the HRC wall of the tube-on-sheet LAHP, where the results of experimental research on the determination of the specific thermal efficiency of the mean-quality FPSWHC in full-scale terms, as well as laboratory and numerical research on determination of the optical and thermotechnical indicators of the copper tube-on-sheet LAHP.
[en] Solar plants are increasingly used not only for hot tap water heating but also for the assistance of space heating. These plants produce much more energy in summer than needed, which often results in stagnation. Because of stagnation-temperatures of todays selective collectors up to 200 deg. C, the collector fluid evaporates. In several plants a high noise level and a vibration of the plant during this evaporation phase is reported. This is due to the occurrence of water hammers in the system, when liquid collector fluid passes areas where the fluid was already evaporated and superheated. The remaining vapor bubbles deflate rapidly and the liquid phases collide with high velocity, which results in a rapid pressure increase. This paper describes the theory of condensate-induced water hammers and conditions of solar plants, under which this can happen. A simulation model for the evaporation phase of the collector is presented to give a deeper understanding about the influences of solar radiation, the size of the tubing, and the size of the expansion device on the process of the evaporation. Three hydraulic layouts of the collector area are discussed for there possibilities producing water hammers. (au)
[en] Seasonal solar energy yields for domestic hot water production are calculated across Estonia, based on the monthly distribution of temperatures and yearly distribution of global solar irradiation. A simplified pulse-mode simulation model was used to describe the processes in a stratified solar system. (author)
[en] The technology of solar water heating is simple and can be used for pre-heating of water entering a boiler. In this paper the economics of solar pre-heating of water was calculated. The calculations were based on the performance and cost of a locally-made flat plate collector, and the performance and fuel consumption of a boiler in a textile mill. The results showed that a collector area of about 800 meter square with initial cost of about LS 5,000,000, could save annually about 130 tons of furnace oil. ( Author )
[en] In a typical solar water heating system, cold water is replenished into the storage tank as soon as the load is served. However, it is possible to determine the water replenishment profile (i.e., the quantity of the cold makeup water to be supplied to the storage tank over a day) that optimizes the overall system. In this paper, the effect of water replenishment on the system sizing is studied and a novel strategy for water replenishment is proposed to improve the design and performance of solar water heating systems. Based on an analytical technique, an approximate water replenishment profile is proposed to size a solar water heating system near-optimally. The problem is analyzed using a methodology called design space approach. Design space of a solar water heating system identifies all possible and feasible designs on a collector area vs. storage volume diagram. For illustration of the proposed methodology, an example problem is solved. It is observed that the annualized system cost can be reduced by 13.7%. For the cost-optimal system configuration, a reduction of 12.7% in the collector area and 10.2% reduction in the storage volume are observed. The proposed methodology is particularly important and advantageous for large commercial and industrial solar water heating systems
[en] The use of regenerative energies began in greece in 1974. Solar energy for hot water preparation has evolved best mainly for favourable climatic conditions. More than 50% of Europe's collector capacity is produced and used in Greece. Solar energy, collectors, heat pump, alternative energies are terms used by greece people in day-to-day life. The author discusses the significance of the greece solar market and its economic aspects. (orig.)
[de]Die Einfuehrung von regenerativen Energien auch in Griechenland hat seit 1974 angefangen. Aus verschiedenen Gruenden, hauptsaechlich aber, wegen der guenstigen klimatischen Verhaeltnisse, ist die Sonnenenergie zur Warmwasserbereitung am weitesten entwickelt worden. In Griechenland wird heute ueber 50% der Kollektorenkapazitaet Europas produziert und eingesetzt. Solarenergie, Kollektoren, Thermosyphon-Anlagen, alternative Energien sind Woerter, die im taeglichen Leben der griechischen Einwohner zu treffen sind. Die Bedeutung des griechischen Solarmarktes und ihre wirtschaftlichen Aspekte werden im vorliegenden Referat erlaeutert. (orig.)
[en] In this paper we present a novel solar concentrating application, a coffee brewing system using a satellite TV mini-Dish concentrator coupled to a stovetop espresso coffee maker. We present a theoretical model for the thermal behavior of the water in the lower chamber of the coffee maker. We validate the model obtaining good agreement with the experimental results. Our findings indicate that the coffee brewing system works, it takes 30-50 min to complete its task. The model and our practical experience encourage us to improve the concentration device in order to obtain a useful solar coffee maker, using the theoretical model as a safe guide to achieve this.
[en] In Denmark it has been put forward that the introduction of solar heating prepared tanks into the building regulation can cause increased nuisance with respect to bacterial growth in hot water for domestic use. The reason is that solar heating prepared tanks have a larger volume and another form of operation than traditional tanks. In this investigation the difference between bacterial growth in solar heating prepared and traditional tanks was measured by heterotrophic plate counts as a general parameter for microbiological growth. There was no significant difference between the bacterial number in the solar heating prepared tanks and in the traditional tanks, either for bacteria determined at 37 deg. C, 44 deg. C, 55 deg. C or at 65 deg. C. The hot water for domestic use from the solar heating prepared tanks and the traditional tanks had in most cases a bacterial number below 1.000 CFU/ml, and all tests had a bacterial number below 10.000 CFU/ml. The number of bacteria must be considered low seen in relation to the other measurements of bacteria in hot water for domestic use, particularly in larger block of flats. (au)