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Thermal conductivity measurements were performed on polyamide 12 and polyamide 11 powders containing carbon nanotubes using the Transient Plane Source, TPS technique. The effects of powder density and temperature on thermal conductivity were investigated, as well as the effects of using previously heated powder. The thermal conductivity was found to increase with increasing density. For tests involving fresh powder, the thermal conductivity was found to increase linearly with temperature. For the previously heated powder, the thermal conductivity was more constant and higher than the fresh powder.
A chalcogenide glass was prepared and doped with carbon nanotubes (CNTs) in an effort to increase the electrical and thermal conductivity of the glass. The glass that was used in this study was Se85Te10Ag5 which was prepared by melt-quenched method. CNTs were added to the glass at 3 and 5 wt. % and the properties of the composite glasses were compared with those of the pure chalcogenide glass. It was found that doping of Se85Te10Ag5 glass with CNTs increased the electrical and thermal conductivities, as well as the microhardness in comparison with pure Se85Te10Ag5 glass.
The potential for the use of multi-walled carbon nanotubes (MWCNTs) for the adsorption of ammonia in solid-gas adsorption refrigeration applications has been investigated by experimental determination of ammonia adsorption properties, as well as the thermal conductivity of a composite adsorption material. In addition to this, two models for estimating the adsorption of ammonia on MWCNTs were evaluated. It was determined that the adsorption amount of ammonia on MWCNTs at equilibrium increased with an increase in pressure, and that it also increased with a decrease in the temperature of the adsorbent. The thermal conductivity of the MWCNT/calcium chloride composite adsorbent was found to be lower than that of pure MWCNTs, but 8 times higher than that of CaCl2. The ammonia adsorption capacity of MWCNTs was much lower than that of the traditional material used in solid-gas adsorption refrigeration, and so it was concluded that MWCNTs are not suitable for this application. However, since the thermal conductivity of the composite material was higher than that of CaCl2, MWCNTs could potentially be used as an additive to this chemical adsorbent.
The use of organic compounds as phase change materials (PCMs) is limited by the low thermal conductivity of these compounds. In this study, multi-walled carbon nanotubes (MWCNTs) and carbon nanofibers (CNFs) were dispersed in n-octadecane to determine if this nanocomposite PCM would have a higher thermal conductivity than that of pure n-octadecane. The thermal conductivity of the nanocomposite PCMs was measured using the Transient Plane Source, TPS method at mass fractions from 0 to 5% and temperatures from 5 to 55oC. It was determined that the PCM/MWCNT composites were more thermally conductive than the PCM/CNF composites with the same mass fraction of filler in both the liquid phase and the solid phase. In both types of nanocomposites that were prepared, it was found that the thermal conductivity increased with increasing filler content. A predictive model was also developed to assist in predicting the performance of a thermal storage composite.
Al2O3, TiO2 nanoparticles, and carbon nanotubes were added to Iraqi paraffin wax in varying quantities to determine the optimum filler content for the enhancement of thermal conductivity. The thermal conductivity was enhanced by 65 and 40% for samples containing 5 wt. % of Al2O3 and TiO2 nanoparticles, respectively. It was concluded that the addition of these nanoparticles to paraffin wax enhanced the thermal conductivity of the phase change material without sacrificing its energy storage capacity.
