Unglazed solar thermal collector for building facades

Abstract

In this paper, a novel concept of an unglazed solar thermal facade collector (USTFC) was developed based on a commercially available metal cladding facade system. A detailed mathematical model of USTFC was developed. To validate the developed mathematical model, five prototypes of the USTFC, different in design, were prepared and experimentally tested. To demonstrate the application potential of the USTFCs for a solar domestic hot water (SDHW) system, a whole year simulation analysis was performed in the TRNSYS simulation software using the validated mathematical model under three different climatic conditions (Stockholm, Prague, and Barcelona). The simulation results showed that the efficiency of the USTFC-based SDHW system is strongly dependent on climatic conditions. The highest SDHW system efficiency of 14.5% was obtained for Prague and the lowest SDHW system efficiency of 11.7% was obtained for Barcelona. The influence of the solar storage volume to the collector field area ratio on the performance parameters of the presented SDHW system was also investigated. It was found that a value of 35–45 l/m2 can be used as the first estimation for the preliminary USTFC-based SDHW system configuration.