Experimental investigation on the stability and heat transfer enhancement of modified mircoencapsulated phase change materials and latent functionally thermal fluids

Abstract

In this paper, the thiol-modified paraffin/silica microencapsulated phase change materials (MEPCM) was synthesized using tetraethoxysilane (TEOS) and (3-mercaptopropyl)-trimethoxysilane (MPTMS) by interfacial co-hydrolysis and co-polycondensation as the aim of improving the thermal stability and suspension stability. The effect of MPTMS was analyzed by SEM, TEM, FT-IR, DSC, TGA, the leakage test and gravity sedimentation test. The most satisfied sample (S3) showed a high thermal storage density of 125.82 J/g, along with an encapsulation efficiency of 65.74%. It also appeared excellent thermal stability after 1000 cycles with 94.11% latent enthalpy remained and kept 99.48% mass after heating at 80 °C more than 150 min. Beneficial from the hydrophobicity regulation by the thiol functional group, the MEPCM exhibited the good suspension stability for 14 days without any surfactant. The modified MEPCM was used to prepare latent functionally thermal fluids (LFTF), which presented 41% improvement of the heat transfer performance when 2wt% MEPCM was added. In addition, a layer of copper nanoparticles was successfully synthesized on the surface of MEPCM for the thermal conductivity enhancement. Therefore, the modified MEPCM provided a new sight on the interfacial modification of MEPCM and has a significant potential for new type thermal fluids.