Articles techniques et présentations

Solar thermal energy, compared to fossil fuels, is an environmentally friendly alternative for heating and hot water production. Recent research suggests that polymeric materials can be a cost-saving and environmentally friendly alternative to the common metals used in solar thermal collectors. During the extrusion process of twin-wall sheet absorbers, a natural deformation of the profiles cross-section occurs, caused by the shrinkage behavior of the polymer. Changes in the cross-sectional geometry may lead to an unfavorable distribution of the thermo-mechanical stresses in the absorber and influence in consequence the service life of the material. In service, the absorber temperature changes depending on the environmental factors, such as ambient temperature and solar radiation, as well as different operating conditions. To study the effect of deformations on real twin-wall sheets as well as their mechanical behavior, the total stress at one point is calculated, consisting of thermal and mechanical stresses in this point.