Klemens Schwarzer, Jan Kroker, Markus Rusack

Fachhochschule Aachen / Campus Julich
Solar-Institut Julich (SIJ)

Heinrich-Mufimann-Str. 5, D-52428 Julich, Germany
Corresponding Author: schwarzer@sij. fh-aachen. de

Abstract

Throughout an earlier research project the Solar-Institut Julich (SIJ) developed a small sin­gle axis tracking modular parabolic trough collector with an evacuated absorber tube, a high — reflective aluminium mirror, an anti-reflective solar glass cover and a step motor drive with worm gear and tracking system. In consequence of the small aperture area of 2 m2 the collec­tor is lightweight and can be used for roof mounting. The aspired operating temperature level is 120 to 200 °C. Measurements and regression analysis have shown an overall effi­ciency of approximately 63 % at a working temperature of 160 °C (relating to 800 W/m2 of solar direct radiation).

In March 2007 the SIJ has started a further research project in association with four partners of the German industry in apparatus engineering, absorber technology and drive engineering. The main aim of the project is the improvement of the collectors’ technical characteristics and its thermodynamic performance. In addition the production costs are to be reduced. Fur­ther the project aims at a series production of the collector.

The project is state-aided by the German Federal Ministry of Education and Research. Keywords: small parabolic trough collector, collector deep drawing, collector improvement

1. Background

Throughout an earlier research project from 2003 to 2005 the Solar-Institut Julich (SIJ) developed a small single axis tracking modular parabolic trough collector, named PTC 1000. Possible appli­cations are the supply of process heat for hotels and hospitals, for industry applications and for the supply of cooling energy. With the end of the project the construction of the collector was finished and three prototypes were built.

Since March 2007 the SIJ tends to optimize the PTC 1000 prototype in a continuative project since weak points not only of constructional background had been detected throughout the testing phase. The main aim is to achieve a series-production readiness. The project is accomplished in collabora­tion with four partners of the German industry in apparatus engineering, absorber technology and drive engineering, which are Wallstein Ingenieur-Gesellschaft mbH, NARVA Lichtquellen GmbH + Co. KG, Ingenieurburo Annas & Partner GmbH and SMF Spanlose Metall Formung GmbH & Co. KG.

The project is divided into four work packages: In the first stage, which ended end of Octo­ber 2007, the weak points of the prototypes such as thermodynamic and technical deficiencies have been identified and a specification sheet for the new collector design has been elaborated. In the second stage concepts for the individual components have been worked out in detail and the new design concept of the collector has been decided at the end of June 2008. Currently, a detailed planning takes place, so that the production can start in September 2009. In the last work package the newly developed collector prototypes will be set up at the test facility of the SIJ and perform­ance tests will be carried out to evaluate the new collector design.

To show the demand of optimization regarding the collectors’ construction and thermodynamics, the features and the determined deficiencies of the prototype are described in the following.