Summary Using palmitic acid (PA) as an organic phase change material (PCM), a series of PA/diatomite composite PCMs (CPCMs) composed of PA absorbed into diatomite mesopores with different mass contents were made through direct impregnation method. Nitrogen adsorption‐desorption curves indicated the porous structure of diatomite with the specific surface area and the mesopore peak at 40 m2/g and 3 to 5 nm, respectively. The form‐stability measurement indicated that the maximum mass loading capacity of PA was 55 wt%. The melting temperature and fusion enthalpy of the PA/diatomite CPCM (55 wt%) were calculated from DSC at 63°C and 88 J/g, respectively. The thermal cycle test implied that the PA/diatomite CPCM with 55‐wt% PA loading showed excellent thermal reliability after 1000 thermal cycles. Moreover, the composite has thermal conductivity at 0.5810 W/m·K and enhanced thermal storage/release rate. PA/diatomite CPCM (55 wt% PA) was a suitable candidate for modern building energy saving and industrial solar energy.

In this study, a new kind of 1-hexadecanol-palmitic acid (HD-PA) binary eutectic mixture and the composite phase change materials (PCMs) composed of HD-PA absorbed into activated carbon (AC) pores with different mass percentage of 50, 55, 60, and 65% were prepared by vacuum impregnation method. The chemical structural, thermal stability and thermal durability of HD-PA/AC composite phase change materials (CPCMs) with different mass fraction of HD-PA was characterized by Fourier transformation infrared (FT-IR) spectrometer, differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA), respectively. The specific surface area of AC were determined to be 760 m 2 g À 1 and abundant mesopores and micropores with the sizes at 1.8 and 0.6 nm were observed according to the N 2 adsorption-desorption measurement. DSC results showed that the onset melting temperature and latent heat of novel HD-PA eutectic were 50.2°C and 226.6 J g À 1 , respectively. The addition of AC to the PCM of binary HD-PA eutectic can enhance its thermal stability, durability and thermal energy storage-release rate. The form-stable HD-PA/AC CPCM can be used as energy storage materials in many fields owing to its good thermal properties and chemical stability.Keywords: binary eutectic mixture · energy storage · 1hexadecanol · palmitic acid · phase change material · thermal properties

No abstract

This study described the synthesis and the tribological properties of surface-modified Field’s alloy nanoparticles, which were prepared by a facile one-step nanoemulsion method and using ethyl carbamate as a surfactant, as additives in liquid poly-alfa-olefin (PAO) oil. The size and morphology of nanoparticles were investigated by transmission electron microscopy (TEM). The zeta potential, viscosity, and stability properties of the surface-modified nanoparticles suspended in PAO oil (called nanofluid) with different mass concentrations were measured by a viscometer and Zeta potential analyzer, respectively. The tribological properties of the nanofluid were tested by a ball to disk wear and friction machine. Compared with pure PAO oil, the results showed that the nanofluids had better lubricating behaviors. When the mass concentration of modified nanoparticles was 0.08 wt. %, both the friction coefficient and the wear scar diameter were the lowest.

No abstract