Development of a solar calorimeter for the thermal evaluation of glazing samples

This work presents the design, construction, and instrumentation of a calorimeter with solar tracking to determine the thermal and optical properties of monolithic glass samples of 15 cm × 15 cm with a maximum thickness of 6 mm. The calorimeter was designed considering an abstract methodology, where the materials, for each of its components, were selected from an evaluation considering its properties and its criteria of functionality. The prototype was constructed and instrumented to quantify the heat losses through each of its walls. The prototype was calibrated to obtain the uncertainty of the heat flows, considering the heat gains and heat losses of the system. The results of the calibration allowed to obtain the uncertainty in the measurement of the heat flow that was estimated as ±0.446 W. On the other hand, to verify the operation of the solar calorimeter, we determined the U-value and solar heat gain coefficient for a 3-mm clear glass sample. The average values obtained for U and solar heat gain coefficient were 6.95 ± 0.9 W m⁻² K⁻¹ and 0.803 ± 0.03, respectively. These values were compared with values reported in the literature, and they have a maximum difference of 7.7%. The uncertainty obtained in the calibration and the values of the characteristic parameters indicate that the solar calorimeter is adequate to obtain the characteristic parameters of monolithic glass samples with optical characteristics similar to the samples of this study.