Abstract :
An experimental study on the phase change behavior of organic phase change materials (PCMs) in porous building materials is
reported. Three kinds of porous materials and two kinds of PCMs were used. The phase change behavior of organic PCMs and phase
change composites was measured by means of differential scanning calorimetry (DSC). The pore structure of the porous materials was
characterized by means of mercury intrusion porosimetry (MIP). X-ray fluorescence spectrometry (XRF) and Fourier transformation
infrared spectroscopy (FTIR) were used to characterize the chemical properties of porous materials and phase change materials. Quite
different phase change behaviors were found for these two kinds of PCMs in porous materials. For capric acid with a functional group of
–COOH, a remarkable elevation of melting temperature was found when confined in porous materials. But for paraffin with only inactive
functional groups of –CH2 and –CH3, no elevation or depression of the melting temperature was found when confined in the porous
materials. The interaction between functional groups of PCM molecules and alkaline spots on the inner pore surface of the porous materials
and the Clapeyron equation were used to explain the different shift of the phase change temperature of capric acid and paraffin in
porous materials.
2006 Elsevier Ltd. All rights reserved
