Thermo-optical reaction changes of a PCM filled glass system

Abstract

Abstract This paper analyzes thermo-optical reactions of the PCM-based glass element which has the capability to store thermal energy together with a variable transparency level through the energy storage process corresponding to phase change. Optical properties are determined by the level of phase transition at given boundary conditions over time. Special uncommon thermo-optical changes occur during its internal phase transition processes, from liquid to solid phase and vice versa (latent heat of fusion) within a given narrow range of temperature interval. PCM acts as random and diffusive media with relevant scattering effects in solid phase, however in liquid state are highly transparent with direct transmission and no relevant scattering effect. These internal physical changes were detailly identified by experimental test procedures based on optical properties measurements performed using a spectrophotometry, and parallelly with the stabilization of each temperature set provided by environmental chamber. As result of that, relevant differences in the PCM spectral feature can be identified for its different states (solid/liquid) in which transmittance spectra are unstable during rapid phase change process. This provides a substantial base line for the optimization of a PCM glazing system in terms of various degree of freedom for different building types and climate zones.