Quasi-elastic neutron scattering (QENS) and pulsed-field-gradient nuclear magnetic resonance (PFG-NMR) analyses of a nanofluid composed of silicon dioxide (SiO₂) nanoparticles (sized 100, 300, or 500 nm) and a base fluid of ethylene glycol aqueous solution were performed. The aim was to elucidate the mechanism increase in the thermal conductivity of the nanofluid above its theoretical value. Typically, the self-diffusion coefficient of liquid molecules in nanofluids can indicate the effect of the nanoparticles on thermal transport in nanofluids as well as the molecular dynamics of the liquid surrounding the nanoparticles. At 298 and 333 K, the obtained experimental results indicate that SiO₂ particles may decrease the self-diffusion coefficient of the liquid molecules in the ethylene glycol aqueous solution because of their highly restricted motion around these nanoparticles. The self-diffusion coefficient of the liquid molecules comprising 300 nm-sized particles is lower than that of the nanofluids comprising 100 and 500 nm-sized particles. At a constant temperature, the thermal conductivity increases as the self-diffusion coefficient of the liquid molecules decreases in the SiO₂ nanofluids.

准弹性中子散射 (QENS) 和脉冲场梯度核磁共振 (PFG-NMR) 分析由二氧化硅 (SiO ₂ ) 纳米粒子（大小为100、300或 500 nm）和基液组成的纳米流体乙二醇水溶液进行。目的是阐明纳米流体热导率高于其理论值的机制。通常，纳米流体中液体分子的自扩散系数可以表明纳米颗粒对纳米流体中热传输的影响以及纳米颗粒周围液体的分子动力学。在 298 和 333 K 时，获得的实验结果表明 SiO ₂颗粒可能会降低乙二醇水溶液中液体分子的自扩散系数，因为它们在这些纳米颗粒周围的运动受到高度限制。包含300nm尺寸颗粒的液体分子的自扩散系数低于包含100和500nm尺寸颗粒的纳米流体的自扩散系数。在恒定温度下，随着液体分子在 SiO ₂纳米流体中的自扩散系数降低，热导率增加。