The thermal analysis of melting process of phase change material in rectangular latent thermal energy storage unit is presented herein. To resolve the low heat transfer rate due to the low thermal conductivity of pure paraffin (the phase change material of this study), the nano-paraffin approach has been numerically investigated. Four nano-metal oxides (Al₂O₃, MgO, SiO₂ and SnO₂) with high thermal conductivity are dispersed into the pure paraffin at different concentrations (1 %, 3 % and 5 %, v/v). The adopted mathematical model that has been used to study the mass, momentum, and energy transport processes inside the nano-paraffin systems has been firstly validated by available literature data. The obtained results showed that both heat transfer and solid melting rate are significantly improved in the presence of nanomaterials, with an independent relation to the particles concentration for a long melting time, i.e. up to 10 000 s. However, above 10 000 s, high particles concentration slightly enhanced the liquid fraction. Besides, it is found that the type of particles did not affect appreciably the heat transfer and the solid melting rate. Nevertheless, the enhancing effect of the nano-paraffin system is strongly melting time dependence. For the four investigated metal oxides, the temperature system attained 351 K at 1000 s of operation, whereas that recorded for the pure paraffin at the same time is 345 K, which yields an improvement of 1.7 %. For the same conditions, the liquid fraction passes form 0.04 for pure paraffin to 0.1 for nano-paraffin system, showing 150 % of enhancement in the melting yield.

本文介绍了矩形潜热储能单元中相变材料熔化过程的热分析。为了解决由于纯石蜡（本研究的相变材料）的低导热率而导致的低传热率，对纳米石蜡方法进行了数值研究。将四种具有高导热性的纳米金属氧化物（Al ₂ O ₃，MgO，SiO ₂和SnO ₂）以不同的浓度（1％，3％和5％，v / v）分散到纯石蜡中）。用于研究纳米石蜡系统内部质量，动量和能量传输过程的数学模型已首先通过现有文献数据进行了验证。获得的结果表明，在纳米材料的存在下，传热和固体熔化率均得到显着改善，并且与长时间熔化时的颗粒浓度无关，即高达10000秒 但是，在10000 s以上，高颗粒浓度会稍微提高液体分数。此外，发现颗粒的类型没有明显地影响热传递和固体熔化速率。然而，纳米石蜡体系的增强作用是强烈的熔化时间依赖性。对于所研究的四种金属氧化物，在1000 s的运行温度下温度系统达到351 K，而同时为纯石蜡记录的温度系统为345 K，提高了1.7％。在相同条件下，纯石蜡的液体馏分从0.04变为纳米石蜡体系的0.1，表明熔融产率提高了150％。