Characteristics of phase-change materials containing oxide nano-additives for thermal storage
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NANO EXPRESS
Open Access
Characteristics of phase-change materials containing oxide nano-additives for thermal storage Tun-Ping Teng* and Chao-Chieh Yu
Abstract In this study, the authors report the production of nanocomposite-enhanced phase-change materials (NEPCMs) using the direct-synthesis method by mixing paraffin with alumina (Al2O3), titania (TiO2), silica (SiO2), and zinc oxide (ZnO) as the experimental samples. Al2O3, TiO2, SiO2, and ZnO were dispersed into three concentrations of 1.0, 2.0, and 3.0 wt.%. Through heat conduction and differential scanning calorimeter experiments to evaluate the effects of varying concentrations of the nano-additives on the heat conduction performance and thermal storage characteristics of NEPCMs, their feasibility for use in thermal storage was determined. The experimental results demonstrate that TiO2 is more effective than the other additives in enhancing both the heat conduction and thermal storage performance of paraffin for most of the experimental parameters. Furthermore, TiO2 reduces the melting onset temperature and increases the solidification onset temperature of paraffin. This allows the phase-change heat to be applicable to a wider temperature range, and the highest decreased ratio of phase-change heat is only 0.46%, compared to that of paraffin. Therefore, this study demonstrates that TiO2, added to paraffin to form NEPCMs, has significant potential for enhancing the thermal storage characteristics of paraffin. Keywords: Alumina, Nanocomposite-enhanced phase-change materials, Paraffin, Silica, Titania, Zinc oxide
Background Thermal energy storage (TES) by solar power has become a popular research topic in recent years. Because of the impact of day and night on solar thermal energy storage, thus, the development of efficient energy storage materials will directly influence the utilization efficiency of solar thermal energy storage [1-3]. In general, singlephase thermal energy storage materials require a large storage space, which reduces the usefulness of thermal storage [4,5]. Therefore, developmental research on thermal energy storage materials focuses on phase-change materials (PCMs), and several research results and practical applications have been published [6-10]. Most PCMs have low thermal conductivity, which prevents them from overcoming problems of rapid load changes in the charging and discharging processes [11]. To overcome this obstacle and to obtain excellent thermal properties, studies have proposed various techniques * Correspondence: [email protected] Department of Industrial Education, National Taiwan Normal University, No. 162, Sec. 1, He-ping E. Rd., Taipei City, Da-an District 10610, Taiwan
for enhancing the thermal conductivity of PCMs, such as adding metallic or nonmetallic particles with high thermal conductivity [12-15], inserting fins [16-18], incorporating porous or expanded materials [19-27], inserting fibrous materials [28-31], and incorporating macro-, micro-, and nano-capsules [32-34]. The abovementioned methods for enhancing
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