Simulated Aging and Characterization of Phase Change Materials for Thermal Management of Building Envelopes
ENGINEER RESEARCH AND DEVELOPMENT CENTER CHAMPAIGN IL CONSTRUCTION ENGINEERING RESEARCH LAB
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Because phase change materials PCMs can absorb or release heat when they undergo phase changes solid to liquid, liquid to solid, or solid to gas, they are considered especially promising candidates for use in heating and cooling applications for building envelopes. This work investigated the stability of four commercially available PCMs, and developed an accelerated testing protocol to simulate the long-term performance of PCMs in an operational scenario. The selected PCM s were subjected to up to 5,400 cycles of thermal cycling at 90 minutes per cycle, over wide temperature ranges to simulate 20 years of use in building envelopes. At 3-4 week time intervals, the samples were taken from the thermal cycling chamber and Scanning Electron Microscope SEM micrographs, Differential scanning calorimeter DSC, Thermogravimetric Analysis TGA, and Fourier Transform Infrared Spectroscopy FTIR data were obtained and compared to baseline pre-cycling data. Results indicated that baseline latent heat values and freezing and melting transition temperatures were generally in accordance with the manufacturer s stated values. All PCM materials evaluated tended to lose some latent heat storage capacity as they underwent thermal cycling.