In situ built-up air collector with glass cover

In the first part of the project background information was gathered describing different jointing methods and materials that can be used for glass joints. In the light hereof indoor tests with different methods of jointing between glass were carried out. From this information a test box was built with a cover of glass where the horizontal joints were made by means of different methods and materials.

As a general principle a water-damming border at the horizontal glass joints was avoided. The test box was built as a solar collector with 14 different horizontal joints between the glasses. The box was placed outdoors on a 45° tilted angled south-facing plate so that the joints were exposed to real weather conditions.

At regular intervals the joints were inspected. After about 3-5 months 2 possibly suitable joints were selected to form part of two prototypes, one of which is a newly developed jointing profile. The prototypes were built in the test area of Department of Buildings and Energy. One of the prototypes has the airflow behind the absorber, which is an aluminium plate painted black, whereas the other has the airflow in front of the absorber.

Here the black top side of the insulation acts as an absorber. Efficiency and aair pressure drop were measured. The efficiency of the two air solar collectors was almost similar and at the same level as other corresponding air solar collectors. The air pressure drop was somewhat larger in the case of the solar collector where the air flows behind the absorber.

This is due to the narrower air gap behind the absorber. Condensation has been observed in both the solar collectors, this has not been investigated more explicitly,