Modular building intergraded solar-thermal flat plate hot water collectors

Abstract

In this paper a small integrated flat plate hot water collector was built and tested. The purpose was to demonstrate its features and problems of this integration. The constructed unit utilises the face of an existing brick wall, facing south. The unit is enclosed in a frame of approximately 1.8x1 m and in the frame an insulation layer was placed on the wall, which provides insulation both to the collector and the building itself. As in conventional flat plate collectors, in front of the insulation an absorbing plate was positioned as well as the appropriate header and riser assembly for the water circulation. Finally, the collector was covered with a 5 mm glass and the system was connected to a hot water insulated tank for storing the hot water. The collector was tested during days with good solar radiation. The solar radiation incident on the collector the ambient temperature, as well as the temperatures of the water inlet and outlet during the day, were recorded. The efficiency of the system, defined as the ratio of the useful energy collected over the total solar energy falling on the collector aperture during the same experimental time, was estimated. Furthermore, a second experiment was carried out under stagnation conditions for the measurement of the maximum temperatures the system can attain, which could create fire issues. The calculated maximum efficiency for the system is 56% and is considered as favourable with respect to existing solar collector systems. The collector tested can easily be mounted on a new or an existing wall (retrofitting). Specific solutions for the required piping to and from the collector were also studied. These show that the piping does not present specific difficulties and in co-operation with the architects, the piping can easily be concealed in the construction.