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- Fischer, S, et al.
(författare)
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Collector test method under quasi dynamic conditions according to the European Standard EN 12975-2
- 2004
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Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X. ; 76, s. 117-123
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Konferensbidrag (refereegranskat)abstract
- In April 2001 the new European Standard EN 12975:2000: ''Thermal solar systems and components--Solar Collectors'' was established. With the publication of this European standard all national standards, related to the same topic, have to be withdrawn by the nations of the European Community. Now only one standard for testing solar collectors is valid throughout Europe.This European Standard specifies test methods for validating the durability, reliability and safety requirements for liquid heating collectors. The standard also includes two alternative test methods for the thermal performance characterization for liquid heating collectors. Apart from the well-known test method under steady-state conditions according to ISO 9806-1, ISO 9806-3 and ASHRAE 93-77 the EN 12975 permits a quasi-dynamic test method for the thermal performance characterization of solar thermal collectors.This paper presents the improved approach to outdoor performance testing of solar thermal collectors under quasi-dynamic test conditions. The test requirements and collector theory are closely connected to those long agreed on for steady-state testing, as described in the ISO and ASHRAE standards mentioned above. The most important effects for the all day performance of the collector are taken into account. The test method covers most collector designs on the market today (except ICS type). Only some correction terms are added to the basic collector models of the present steady-state test methods. Still this limited change will allow test data to be collected and used from whole days.An important fact is that the collector model used for the parameter identification is written so that the error in collector output power is minimized. Therefore an accurate long-term prediction of the collector performance can be an integral part of the test method, where the same collector model and parameters are used for both testing and prediction.
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- Santos, Olga, et al.
(författare)
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Modified stainless steel surfaces targeted to reduce fouling - surface characterization
- 2004
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Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774. ; 64:1, s. 63-79
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Tidskriftsartikel (refereegranskat)abstract
- The surface properties of several modified stainless steel samples were characterized according to their chemical composition, roughness, topography and wettability. The modifications tested were SiF3+ and MoS22+ ion implantation; diamond-like carbon (DLC) sputtering: DLC. DLC-Si-O and SiOx, plasma enhanced chemical vapor deposition (PECVD); autocatalytic Ni-P-PTFE and silica coating. X-ray photoelectron spectroscopy (XPS) and X-ray microanalysis were applied to determine the surface chemical composition. Atomic force microscopy (AFM) and stylus-type instruments were used for roughness determination, and the surface topography was imaged with AFM and scanning electron microscopy (SEM). The contact angle and surface tension were measured with the Wilhelmy plate method and the sessile drop method. For thick modified layers, only the elements of the coating were detected at the surface, whereas for thin layers the surface composition determined was that of the stainless steel substrate. The roughness of the 2R (cold rolled and annealed in a protective atmosphere) Surfaces was not altered by the modification techniques (except for the Ni-P-PTFE coating), while for the 2B (cold rolled. heat treated, pickled and skinpassed) surfaces an increase in roughness was observed. The silica coating produced surfaces with consistent roughness, independent of which steel substrate was used. DLC sputtering and Ni-P-PTFE coating produced surfaces with the highest roughness. All modified surfaces revealed a similar surface topography with the exception of the Ni-P-PTFE coating, for which the coating masked the underlying steel topography. In terms of wettability, the SiOx-plasmaCVD and NiP-PTFE coating, techniques produced the most hydrophilic and hydrophobic surfaces, respectively. (C) 2003 Elsevier Ltd. All rights reserved.
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