ABSTRACT

The aim of this work was to develop a solar calorimeter for thermal testing of glazings, where indoor and outdoor heat transfer coefficients (h_i and h_o) can be pre-established. Development of the solar calorimeter includes designing, manufacturing, commissioning, and calibrating, where the calibration takes into account verification and characterization. The calorimeter was verified and characterized based on the first thermodynamic law, using both a reference specimen and reference glass. The incoming and outgoing heat fluxes were obtained by measuring changes in the internal energy of the working fluid, as well as by heat flux transducers in the walls. The tests were conducted outdoors at variable clearness conditions in a warm/humid climate. The calibration of the calorimeter revealed an uncertainty of5W of the heat flux through the sample, which implied a lower addition of uncertainty. The experimental solar heat gain coefficient (SHGC) of the reference glass was 0.810 with a deviation of 0.005 with respect to the reference value (0.815). The average h_i and h_o values were consistent with the standard heat transfer coefficients (8.4 and 9.1 W/m²°C), with variations of 0.4 and 3.5 W/m²°C, respectively, during daytime hours (700 to 1800 hrs.). However, during the nighttime hours h_i varied 3.2 W/m²°C. Therefore, in the case of the reference glass, the daytime variations of h_i and h_o induced changes of the SHGC and U value that reached up to 0.012 and 0.77 W/m²°C, respectively.