An Edge-Heating Device for Optical Measurement of Thermochromic Glazing Materials and Recommended Test Procedure

摘要

Thermochromic materials have optical properties that vary with temperature. To simulate energy performance of such materials, it is important to have spectral data in the solar range, 300-2500 nm, for each temperature that the material will have in the simulation. This paper describes a temperature control strategy that allows for measurement of reflectance and transmittance at a fixed temperature using a commercial spectrophotometer. A specimen frame is used to clamp heating strips to the surface at the edge of the sample that is being tested. Multiple thermocouples are used to monitor the temperature gradient over the sample as the center is cooler than the edge. Verification using an infrared (IR) camera and time-resolved transmittance measurements show that the center sample temperature is stable and how long it takes to achieve equilibrium. An interpolation method is described and verified to reduce the number of states that need to be measured. A recommended test procedure is described and used on two different materials.