Comparative analysis of domestic water heating thermosiphon systems tested according to the Standard ISO 9459-2

Permiso concedido para subir el documentoThe Standard ISO 9459-2 is a standard for the characterization of thermal performance of domestic water heating systems without auxiliary heating. In this study, 18 domestic water heating thermosiphon systems have been tested according to this international standard. The objective of the paper is to carry out a comparative analysis of the results obtained in these systems as a function of their volume and type of heat exchanger (tubular and double jacket). A comparative analysis of systems performance will be carried out by calculating the performance without thermal loss (a1/A) and solar fraction fSOL in different reference locations for different volume/area ratios. Also, a comparative analysis of systems performance and solar fraction will be carried out at different locations between a tubular heat exchanger tank and a double jacket heat exchanger tank. The different values obtained will be compared for the storage tank’s heat loss coefficient (Us). It will determinate the useful energy (energy with temperature above 45ºC) for the degree of mixing in the storage tank during a draw-off test

Analiza utjecaja karakterističnih koeficijenata solarnih toplinskih sustava ispitanih prema normi ISO 9459-2 s obzirom na dugoročno predviđanje njihove iskoristivosti

The Solar Thermal Testing Laboratory shared by CENER and GTER in Seville performs outdoor efficiency tests for factory-made solar systems according to the international standard ISO 9459-2.This method (CSTG acronym for “Collector and System Testing Group”, also called the input-output method) consists of three different parts: one part for determining mixing in the storage tank during draw-off, another part for determining daily system performance, and a part for the determination of storage tank heat losses. From the so-called CSTG test, the following coefficients are obtained: the characteristic coefficients of the solar system in the daily performance (a1, a2, a3), the normalized draw-off temperature profile (f(V)), the normalized mixing draw-off temperature profile (g(V)) and the storage tank heat loss coefficient (Us).After having tested some solar systems according to the CSTG method, the long term prediction of the system output is performed using a simulation program. Using the obtained test results as a starting point, we vary the parameters stepwise and observe how this influences the solar fraction fsol. Therefore, the purpose of the present paper is to analyze the influence of those parameter variations on the solar fraction fsol obtained from the long-term prediction in different reference locations (Stockholm, Würzburg, Davos and Athens) and for various solar systems with a different volume/area ratio.Laboratorij za istraživanje solarnih toplinskih sustava u Sevilli kojega koriste CENER i GTER vrši ispitivanja iskoristivosti komercijalnih solarnih sustava prema standardu ISO 9459-2. Ova metoda (zvana CSTG – Collector and System Testing Group) se sastoji od tri dijela: određivanje miješanja u spremniku topline tokom ispusta, određivanje dnevnih performansi sustava, i određivanje toplinskih gubitaka u spremniku topline. Iz CSTG testa, dobiveni su sljedeći koeficijenti: karakteristični koeficijenti solarnog sustava za procjenu dnevne performanse (a1, a2, a3), normalizirani profil temperatura u spremniku topline tokom ispusta (f(V)), normalizirani profil temperatura miješanja tokom ispusta u spremniku topline (g(V)) i koeficijent toplinskih gubitaka toplinskog spremnika (Us). Nakon testiranja solarnih sustava CSTG metodom, dugoročno predviđanje njihove iskoristivosti je izvršeno računalnom simulacijom. Koristeći rezultate ispitivanja kao početnu točku, mijenjani su radni parametri te je promatran utjecaj tih parametara na solarni udio energetskog učina sustava fsol. Ovaj rad analizira utjecaj tih parametara na promjenu solarnog udjela u energetskoj bilanci sustava, što je dobiveno dugoročnim predviđanjem performansi sustava na različitim loacijama (Stockholm, Würzburg, Davos i Atena) za različite solarne sustave sa različitim omjerima volumena toplinskog spremnika i površine kolektora

Solar Thermal Collectors for Medium Temperature Applications: A Comprehensive Review and Updated Database

Although the technology of solar thermal collectors for medium temperature applications is not new, few collectors and commercial installations were available worldwide. Presently the sector is growing rapidly, new technologies have been developed and real installations using these technologies are already being built all around the world for different applications, especially for the generation of heat required by industrial applications. Considering the increasing number of available products and the importance of disseminating this information among system designers and end-users, a database of the available solar collectors for medium temperature applications is under development. The information has been gathered from the different collector manufacturers and suppliers and the available technical information published on the different collector models. Aiming a thorough insight into these new commercially available solutions, the database includes the most relevant technical information of the different existing collectors. This work is being done within the framework of the European project STAGE-STE (Scientific and Technological Alliance for Guaranteeing the European Excellence in Concentrating Solar Thermal Energy) (http://www.stage-ste.eu/). The information gathered will also be used within the Task 49, the working group for Solar Heat Integration in Industrial Process (SHIP) of the Solar Heating and Cooling program (SHC) by the International Energy Agency (IEA) (http://task49.iea-shc.org/).European Commission FP

Optical properties of solar absorbers : results on Round Robin and guidelines

ABSTRACT: 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.info:eu-repo/semantics/acceptedVersio

Accelerated aging test of solar reflectors according to the new AENOR standard – results of a round Robin test

Durability tests of reflector materials for concentrating solar applications are crucial to guarantee the profitability of the plants and to ensure a proper efficiency during their lifetime. A standard including a set of five accelerated aging tests is close to be published by the Spanish standardization entity AENOR, within the sub-committee AEN/CTN 206/SC117. Under the framework of the STAGE-STE project, a Round Robin Test was organized by six partners to evaluate the comparability of results obtained in their respective laboratories after performing these durability tests. According to the results, in general a good agreement among the partners was found, with negligible to slight reflectance losses. In addition, it was noticed that the reference standard used in the reflectance measurements is of high importance. The conclusions of this work will help to improve the standard in future versions.The research leading to this work has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 609837 (STAGE-STE). The authors would like to thank the participants of the working group for solar reflectors of WG 2 of the Spanish sub-committee AEN/CTN 206/SC 117

Towards standardized testing methodologies for optical properties of components in concentrating solar thermal power plants

Precise knowledge of the optical properties of the components used in the solar field of concentrating solar thermal power plants is primordial to ensure their optimum power production. Those properties are measured and evaluated by different techniques and equipment, in laboratory conditions and/or in the field. Standards for such measurements and international consensus for the appropriate techniques are in preparation. The reference materials used as a standard for the calibration of the equipment are under discussion. This paper summarizes current testing methodologies and guidelines for the characterization of optical properties of solar mirrors and absorbers

Identification of autonomous robots and UAV/IAV and completion of systems design

The report outlines the possible integration of remote sensors in both terrestrial and aerial vehicles for fast characterization of line-focus solar fields one of the purposes of the ongoing project STAGE-STE project. Possible tasks of Unmanned Aerial Vehicle (UAV) and Intelligent Autonomous Vehicle (IAV) are covered together with the minimal system requirements