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- European round robin test on solar collectors and solar thermal systemsPublication . Fischer, S.; Carvalho, Maria João; Weißmüller, C.Within the European project QAiST (Quality Assurance in Solar Thermal Heating and Cooling Technology)a Round Robin test on solar collectors and solar thermal systems is carried out in the years 2010 and 2011. For two different collector types, one flat plate collector and one evacuated tubular collector with CPC reflector, thermal performance tests according to EN 12975-2 (EN 12975, 2006) are carried out by 12 different test institutes throughout Europe. The two different solar thermal systems, one thermosiphon system and one system with forced circulation are subject to a thermal performance test according to EN 12976-2 (EN 12976, 2006) and are tested by 9 different test institutes.In order to finish the Round Robin test within two years despite of the high number of participants, the following procedure was applied: Each participant received in the year 2010 samples of the two different collector types and of the two solar thermal system types respectively. After testing, the samples have been sent to the next test institute to be tested within the year 2011. Thus all institutes are testing identical collectors and system types taken out of the same production batch, however each unique collector or system is only tested by two institutes. For the first time Round Robin tests on solar thermal products are evaluated by an independent institute (Institut für Eignungsprüfung) using the acknowledged procedures for the evaluation of proficiency tests.This paper presents some of the midterm results of the Round Robin test in an anonymous and standardised way.
- Optical properties of solar absorbers : results on Round Robin and guidelinesPublication . Carvalho, Maria João; Páscoa, Soraia; Sallaberry, Fabienne; Wilson, Helen Rose; Fischer, S.; Loren, Anders; Bohren, Andreas; Nielsen, Jan ErikABSTRACT: The scope of the standard ISO 22975-3:2014 is the determination of the long term behavior and service life of selective solar absorbers for use in vented flat plate collectors used in typical solar domestic hot water systems or combisystems. With this scope, this standard can be the basis for the certification of solar absorbers in the framework of Solar Keymark European Certification Scheme. Measurements of optical properties are fundamental to support this certification. Six test laboratories participated in a Round Robin test for the measurement of solar absorptance and thermal emittance of different absorber coatings. The samples used were one PVD coating and two selective paint coatings all on aluminum substrates. The results were submitted anonymously and were analyzed according to standard ISO 13528:2015. The results obtained showed good agreement among the measurements made by the participants and allowed the preparation of guidelines to guarantee quality of the measurements of optical properties of solar absorbers. A proposal to include absorber coatings in the Solar Keymark certification scheme was prepared.
- Latest developments in the field of solar thermal standardisationPublication . Fischer, S.; Carvalho, Maria João; Kovacs, P.; Malenkovic, I.The European project QAiST-―Quality Assurance in Solar Thermal Heating and Cooling Technology‖ funded by the Intelligent Energy Europe program and by the participating countries, gathers 15 participating organizations including the European Solar Thermal Industry Federation ESTIF and major testing and research institutes in Europe. The objective of the project is to enhance the competitiveness of the European Solar thermal industry and further increase consumer confidence through improved standards and certification schemes, harmonization in testing and certification and a wide dissemination of the quality concept throughout Europe. Global harmonization in collector standards and certification is also on the QAiST agenda and has taken a large step forward through CEN/ISO cooperation and a strong European representation in the IEA SH&C task 43.
- Solar thermal collector yield: experimental validation of calculations based on steady-state and quasi-dynamic test methodologiesPublication . Horta, Pedro; Carvalho, Maria João; Fischer, S.The characterization of collector efficiency is the fundamental tool for long term calculation of collector yield. It is, thus, one of the most important inputs in software tools aiming the design of solar thermal systems. Presently two test methodologies are available for characterization of the efficiency of glazed collectors: i) steady state test and ii) quasi-dynamic test, methodologies based in different model approaches to a solar collector, providing different collector efficiency curve parameters and, consequently, imposing different power calculation algorithms. Moreover, Horta et al (2008) demonstrated that the use of the collector efficiency curve derived from steady state test method is not enough for a thorough characterization of the long term performance of a collector. The present work takes into account the introduction of the above referred test methodologies in the European Test Standard for Solar Thermal Collectors, and aims at clarifying how each test results should be used in long term thermal performance calculations. The paper presents a synthesis of the different efficiency parameters provided by each test methodology and corresponding algorithms, applicable in the calculation of delivered power. Application of these algorithms to two days of measured data allows for a comparison of the results obtained with these different methodologies. For validation purposes, results of tests performed on a CPC type collector with a concentration ratio C=1.72 are used. Measurement sequences are used to validate the calculation of power delivered by the collector using both algorithms based on steady-state methodology (with and without correction) and quasi-dynamic methodology.