Mechanical and Thermo-Physical Performances of Gypsum-Based PCM Composite Materials Reinforced with Carbon Fiber

Abstract

Phase change materials (PCMs) have received extensive attention due to their high latent heat storage density and isothermal behavior during heat charging and discharging processes. The application of PCMs in buildings would match energy supply and demand by using solar energy effectively, thereby reducing building energy consumption. In this study, a diatomite/paraffin (DP) composite was prepared through a vacuum-impregnated process. The thermo-physical performance, thermal stability, chemical structure and thermal reliability of the DP composite were evaluated. To develop a structural–functional integrated energy storage building material, carbon fibers (CF) were chosen as the reinforcing material. The mechanical and thermal properties of CF-reinforced DP/gypsum were examined. It is evident that the flexural strength and thermal conductivity of DP/gypsum containing 1 wt. % CF increased by 176.0% and 20.3%, respectively. In addition, the results of room model testing demonstrated that the presence of CF could enhance the overall thermal conductivity and improve the thermo-regulated performance of DP/gypsum. Moreover, the payback period of applying CF-reinforced DP/gypsum in residential buildings is approximately 23.31 years, which is much less than the average life span of buildings. Overall, the CF reinforced DP/gypsum composite is promising for thermal energy storage applications.

Influence of the Addition of Carbon Fibres on Gypsum–PCM Mixtures

“…The reason for this decrease was not clearly understood since PCM microspheres were supposed to have thermal conductivities close to conventional gypsum (Table 4). Nevertheless, it could be noted that the same trend was observed for other studies with similar materials [20].…”

“…The addition of shorter carbon fibres also increased thermal conductivity, but the impact was relatively small (from +8% for the Plaster + PCM + 0.5%-150 µ sample to +12% for the Plaster + PCM + 4%-150 µ sample). These values, however, were relatively of the same order of magnitude as those obtained by Zhang et al [20], whose materials, composed of gypsum and PCM, saw an increase in their thermal conductivity of 20% following the addition of 1 wt.% of carbon fibres. Similar influences were obtained by Krause et al [36] when the same type of carbon fibres was used to improve the properties of their studied polymer, obtaining an increase in thermal conductivity of 30% with a doping of 5 wt.%.…”

“…It is worth noting that there is currently no standard method for this type of test. The design of the experimental set-up for this study was developed by Buildwise on the basis of preliminary research available in the literature [19,20].…”

“…The main goal of this work was to study whether the doping of plaster with carbon fibres improved thermal conductivity in order to obtain better efficiency from PCM microspheres. This investigation was inspired by some promising results shown in the literature [19,20]. The exact value of the thermal conductivity of the carbon fibres used in this study was not available.…”

“…In their study, Zhang et al [19,20] used carbon fibres that were 7 µm in diameter and 3 mm long to improve the performance of gypsum board with 10-20 wt % PCM. The results showed that 1 wt % of carbon fibres increased the material's thermal conductivity by up to +36%.…”