Napsugárzást koncentráló nem hagyományos optikai gyűjtőelemek geometriai és energetikai jellemzőinek meghatározása = Determination of geometrical and energetical parameters of non-conventional optical collector elements

A kutatás abból a feltételezésből indult ki, hogy alkalmasan kiképezett, optikai vezetőkből készült prizmatestekkel lehetséges a napsugárzás jelentős mértékű koncentrációja. A számos lehetséges geometria közül a kúp alakú prizmákat vizsgáltuk, amelyek PMMA anyagból készültek. A vizsgálatok bizonyították a hipotézis helyességét. A mérések során 20 és 40 fok kúpszögű prizmatesteket vizsgáltunk. A lézerfénnyel végzett fénymenet-vizsgálatok alapján a 20 fokos kúpszögű prizmák voltak a legmegfelelőbbek, amelyeknél a számított elméleti koncentráció mértéke 17-szeres volt. A természetes (nap) fényben végzett tartós kísérletek azzal az eredménnyel zárultak, hogy az elérhető maximális fénykoncentráció a vizsgált elemekkel kb. hatszoros. Ez azt jelenti, hogy pl. 800 W/m2 fényáram a prizmatestekkel merőleges beesésnél mintegy 4800 W/m2 értékre növelhető. A tényleges koncentráció a beesési szög függvénye, mérések alapján pontosan megadható. Az alkalmazások szempontjából fontos látószöge a prizmáknak 60 fok, az évszakoktól függően kis mértékben változik. A prizmákkal koncentrált sugárzási energia optikai szálban vezethető, azonban jellemzően a szálhosszal arányos veszteségek lépnek fel. Az eredményeket felhasználva napkollektorokhoz olyan gyűjtőfelület (speciális szolár üveg) alakítható ki, amely az imissziót (visszasugárzást) jelentősen csökkenti, így javítja a kollektor hatásfokát. | The premise of the research work was that suitable formed, made of optical fiber prisms are applicable for concentrate the solar radiation considerably. Some of geometry of prism were theoretically tested, but only the conical prisms were tested in laser and sunlight. The material of prisms was PMMA (poly-metil-metacrilat). The tests showed that the hipothesys was right. The conic angle was 20deg and 40deg at the tested prisms. After laser testing the 20deg conic angle was choosen, where the theoretical concentration of the radiation was approximately 17. The maximum of the measured concentration of sunlight was only 6, what means for example, that an 800 W/m2 incline radiation increased to 4800 W/m2 by the optical prisms. The real concentration is depending on the angle of incidence, of course, which was determine with an all year long test at fixed installation angle prism. The so called operating angle of the prism was 60deg. This parameter is changing during a year in a small measure. The concentrated solar radiation energy can be transmitted in optical waveguides, of course, with losses depending on the lenght of the guide. Based ont he results of the research work, can be made a special collector surface for solar collectors (solar glass with high number of prisms), which may reduces the imission light and so increases the efficiency of the collectors

Adoption and evaluation of a sample pre-treatment protocol for radiocarbon dating of cremated bones at HEKAL

L

Adoption and evaluation of a sample pretreatment protocol for radiocarbon dating of cremated bones at HEKAL

A comparative study was undertaken to adopt and evaluate a radiocarbon (14C) preparation procedure for accelerator mass spectrometry (AMS) measurements of cremated bones at our laboratory, including different types of archaeological samples (cremated bone, bone, charcoal, charred grain). All 14C analyses were performed using the EnvironMICADAS AMS instrument at the Hertelendi Laboratory of Environmental Studies (HEKAL) and the ancillary analyses were also performed at the Institute for Nuclear Research (ATOMKI). After the physical and chemical cleaning of cremated bones, CO2 was extracted by acid hydrolysis followed by sealed-tube graphitization and 14C measurement. The supplementary δ13C measurements were also performed on CO2 gas while FTIR was measured on the powder fraction. Based on the FTIR and 14C analyses, our chemical pretreatment protocol was successful in removing contamination from the samples. Good reproducibility was obtained for the 0.2–0.3 mm fraction of blind-tested cremated samples and a maximum age difference of only 150 yr was found for the remaining case studies. This confirms the reliability of our procedure for 14C dating of cremated bones. However, in one case study, the age difference of 300 yr between two cremated fragments originating from the same urn shows that other processes affecting the cremated samples in the post-burial environment can substantially influence the 14C age, so caution must be exercised

Fogyasztói energiastratégia és életminőség

A megújuló energiaforrások széles körű alkalmazása a környezetkímélő energiaellátás és a (hosszú távon kimutatható) költségmegtakarítás révén jelentős hatással lehet az életminőségre. Azonban ma még a megújuló energetikai technológiák nem teszik lehetővé a széles körű elterjedést, mivel a fajlagos beruházási költségek magasak. Remélhető viszont, hogy a költségek folyamatosan csökkenthetők lesznek, és a megújuló energiaforrások kihasználásával jelentkező kedvező környezeti hatások és a megtakarítások az életminőség javulásának irányába hatnak. ------------------ A wide use of renewable energy resources could significantly affect the quality of life because they would provide environment friendly energy at cost saving prices (detectable on long term basis). However, the application of renewable energy resources cannot be widely expanded at present, because specific investment costs into the technology involved is prohibitively expensive. Hopefully costs can be continually reduced and the exploitation of renewable energy resources will affect the environment and energy costs in a way that will lead to improvements in the quality of life

Capillary Volume and Evaporation of Textile Materials

The objectives of the paper were to show that the evaporation intensity of water can be increased by the application of appropriate textile materials. The purpose was to determine the dependence of the evaporation intensity on the textile characteristics and the influence weather conditions on the evaporation intensity of different textiles. Five different textile strips of different widths and of single- and multi-layer were tested in definite experimental pots under open air conditions. The results of the experiments showed the total evaporation surface of the textiles depended on the texture material and the capillary volume of the textiles and the capillary volume had a limit at approximately Vc = 1000–1200 cm3/m2. Another important result was that the relative air humidity is a main factor of the weather conditions that has principal influence on the evaporation intensity. However, the other parameters — such as temperature, solar radiation and wind speed — have only a secondary effect on the evaporation intensity of textiles

Energetic Relationships for Crushing of Soil Clods

Clod crushing is a principal problem with soils of high clay content. Therefore, there is a need for determining the conditions for clod breaking and clod crushing. The objective of the work was to develop a special purpose tool for single clod breaking both by rigid support of the clod and by a single clod supported by soil and to develop a machine for clod crushing. Furthermore, the purpose was to determine the relationship between the specific energy requirement for clod crushing in the function of soil plasticity and the soil moisture content by the means of the developed tool and machine. The main result of the experiments is summarized in a 3D diagram where the specific energy requirement for soil clod crushing is given in the function of the moisture content and the plasticity index for different clay soils

Developing and Testing Solar Collectors

A relatively new trend is the development of concentrator-type solar collectors and cells for the use in micro-concentrators. The geometry of these concentrators is simple, the reflexion surfaces or mirrors are usually flat-plate surfaces. The relations of radiation in the inner spaces of these collectors are complicated. The OSLO optical edition software can be used to study and simulate the light paths in the concentrator elements and resonators, using the laws of geometrical optics. Based on the results of study and simulation, a pilot collector was built for energetic testing. In the applied arrangement, the absorber surface was the heated tube itself and fitted exactly to the inlet concentration surfaces. By this way, the relation of the absorber surface and collecting surface was reduced to 0.25. Since the radiation losses decreased, the efficiency of the pilot collector was relatively high even at high outlet temperature conditions (50% at 50 °C outlet temperature and Δ T = 18 °C). The optical concentration of solar radiation energy is a possible way to increase the liquid heat transporter collector efficiency and the outlet temperature. Importance of air solar collectors is lower, but their application in some agricultural post-harvest processes (drying, desiccating) may be useful and profitable. A flat-plate-plate solar air collector was built and tested, with special absorber geometry and material. The results of tests are also shown in this study. The proved daily ΔT-asymmetry at both of pilot collectors is an important result for the practice. Practically it means that the afternoon hours are more favorable for the energy production than the morning hours. Since this effect probably exists in all types of solar collectors, the practice of horizontal direction of collectors needs modifying