Modeling Software

Theoretical modeling was done applying a software generated by AEE INTEC (Gleisdorf, AUT), which provides a comprehensive theoretical mathematical description of flat-plate solar collector performance [4]. It allows for the evaluation of collector conversion factors and for the determination of efficiency graphs. For the present investigation specific functional elements, such as thermotropic layers have been implemented additionally. In real mode of operation the maximum absorber temperatures are a function of climatic conditions, incident irradiation and angle of incidence. To evaluate the frequency distribution of the maximum absorber temperatures in the course of the year a statistic module was implemented. Basically this software considers

• direct, diffuse and scattered solar irradiation reaching the absorber,

• transmission, absorption and reflection on multi-layer collector glazing including the thermotropic layer,

• solar absorption and reflection as well as thermal emission of absorber coatings,

• heat transport from absorber to fluid

• heat losses by convection, thermal conduction and radiation due to collector glazing and casing and

• climate data for Graz (for the statistic module).