The
capric acid (CA)/diatomite (DT)/carbon nanotube (CNT) ternary
system was investigated to develop a shape-stabilized composite phase
change material for thermal energy storage via the direct impregnation
method. DT was used as the supporting material to absorb CA and prevent
its leakage. It was found that good form stability could be obtained
when the loading of capric acid in the CA/DT composite reached about
54%. Furthermore, CNTs were added into the CA/DT form-stable phase
change material (FSPCM) to enhance the thermal conductivity of the
binary system. Moreover, the X-ray diffraction, scanning electron
microscopy, and Fourier transform infrared spectroscopy analyses were
carried out to characterize the microstructure and chemical properties
of the composite PCM. The thermal properties of the prepared form-stable
phase change materials (FSPCMs) were determined using differential
scanning calorimetry (DSC) and thermogravimetric analyses. The analysis
results showed that the components of the FSPCMs were in good compatibility
and CA is well-infiltrated into the structure of the DT/CNT matrix.
DSC analysis indicated that the latent heat of fusion of the ternary
system was 79.09 J g–1 with a peak melting temperature
of 31.38 °C. The thermal conductivity of the CA/DT/CNTs increased
from 0.15 to 0.48 W m–1 K–1, with
only 7 wt % of CNTs. It is shown that the thermal conductivity of
the ternary system was greatly enhanced by the addition of CNTs. The
thermal conductivity increased by 1.56 times compared to that of the
binary system. Moreover, the enhancing mechanisms of heat conduction
transfer by CNTs were revealed by taking advantage of energy wave
theory.
Porcelain tiles are a building material that has been widely used in recent years and that consumes substantial resources during the sintering process. This study reports on the production of low-temperature porcelain tiles by using low-grade lithium ore (LO) and silica crucible waste (SCW) in a new SiO2–Al2O3–Na2O–K2O–Li2O system. The firing temperature of the porcelain tiles was reduced from 1260 °C to 1070 °C by adding 30% LO instead of feldspar in a modified triaxial ceramic body, and SCW was recycled and used as a raw material. These actions help to reduce the carbon emissions produced during sintering and achieve sustainable development. The effect of phase transitions on the sintering and technological properties of the porcelain tiles was studied by quantitative phase analysis, using X-ray diffraction (XRD). Secondary mullite (0–19%) can be formed at 1040–1100 °C, where more quartz and cristobalite will be retained, which increases the rupture modulus of the porcelain tiles. While the vitreous phase increases rapidly at 1100–1160 °C, the closed pores (0.1–33.1%) will simultaneously expand, causing a decrease in compactness. The results show that low-grade LO (with a cost similar to that of feldspar) allows for the production of porcelain tiles with better process performance at lower temperatures (≤1100 °C).
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