LAUSR

Abstract The functionalized TiO2 nanoparticles(β-CD-TiO2-Ag) were manufactured and their characteristics were studied. The thermal storage characteristics of β-CD-TiO2-Ag cooling medium-based nanofluids as an innovative kind of phase change material for eco-friendly cold thermal energy systems were investigated. Dispersion stability is an important research focus for the cooling medium with nanoparticles and this research demonstrated that cooling medium-based nanofluids had good stability. The thermal conductivity of cooling medium-based nanofluids was measured, which was an evident method to improve cold thermal energy storage characteristics. The supercooling behavior of cooling medium-based nanofluids containing β-CD-TiO2-Ag, TiO2 and pure cooling medium was investigated. The experimental results showed that β-CD-TiO2-Ag nanofluids had an observably lower supercooling degree than both of the pure cooling medium and TiO2 nanofluids with the same volume fraction. Moreover, the total freezing time of β-CD-TiO2-Ag nanofluids was less than that of pure cooling medium with volume fraction increased. Supercooling degree could decrease by 63% from 14.6 °C to 5.4 °C with the addition of 0.1 vol% β-CD-TiO2-Ag nanoparticles. These promising results indicated that this research has huge potential in improving the performance of eco-friendly cold thermal energy storage systems and saving resources protecting environment.