Fig nbsp xA Comparison between vacuum impregnation and
Fig. 6. Schematic of the vacuum impregnation set up .Figure optionsDownload full-size imageDownload as PowerPoint slide
A comparative study was presented by Barreneche et al.  several gypsum samples with different PCM incorporation methods (microencapsulation, direct incorporation and impregnation) were studied. Found that the effective thermal conductivity decreased in all samples except in the impregnated one. This fact was due to the G418 of the air by the PCM in liquid state and hence decreasing the porosity of the sample.
The ability of different types of porous aggregate to absorb butyl stearate was studied by Zhang et al. . The three aggregate types investigated were expanded clay (C1), normal clay (C2) and expanded shale (S). Table 1 below shows the PCM absorbing capacity for the porous aggregates.
PCM absorbing capacity for the porous aggregates .NotationDensity (g/cm3)Porosity (%) (MIP)Water-absorbing capacity by simple immersion (%)Water-absorbing capacity by vacuum impregnation (%)PCM-absorbing capacity (ml) per 1 g of porous aggregateC10.7675.611.072.50.876C21.2541.95.942.50.176S1.3933.84.115.00.081Full-size tableTable optionsView in workspaceDownload as CSV