Test loop for inter-connections of parabolic trough collectors

Abstract

The Spanish Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT) through its Plataforma Solar de Almería (PSA), started a program for testing outdoor every individual component of parabolic trough collectors (PTC), i.e. structure, mirrors, absorber tubes, etc., reproducing real solar conditions as well as in laboratories using accelerated aging chambers or appropriate test loops. A very important part pending of testing in an ad-hoc facility were the collectors’ inter-connections (ball joints, flexible hoses and hybrid interconnections). In that sense, CIEMAT-PSA and the German Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) agreed to erect a common test bench at PSA. The so called Rotation and Expansion Performing Assembly (REPA) enables specific test as well as accelerated full lifecycle tests under realistic conditions, using silicone or mineral oil based HTFs at temperatures up to 450°C. It was erected and commissioned at PSA and it will start its operation late 2017: The REPA test facility is the result of merging CIEMAT activities in task 14.4 of the European project SFERA-II and DLR activities within the work package 6 of the national German project StaMeP. In a solar power plant with parabolic trough collector (PTC), one of the main technical constraints in the solar field is dealing with the absorber tubes thermal expansion and collectors rotation motion. The non alignment between the collector focal line and the rotation axis is a key point in the construction of this type of solar field. As consequence, the connection interface between the receiver tubes of adjacent PTC in one side and between headers and both loop ends in the other, must be accomplished using elements tested in real conditions able of absorbing that stress.