Abstract

The public domain is inundated with discrepancies in numerical and experimental findings on the natural convection heat transfer performance of nanofluids in a cavity. This paper presents the experimental investigation of the natural convection of deionized water (DIW)-based zinc oxide (ZnO) nanofluid in a rectangular cavity. The ZnO nanoparticles (20 nm) were dispersed in DIW to formulate nanofluids at various volume concentrations (0.10, 0.18, 0.36, 0.50 and 1.0 vol.%). The spectrophotometer and zeta potential were used to verify the stability of ZnO/DIW nanofluid at various temperatures and concentrations. ZnO/DIW nanofluids and DIW were charged into a rectangular cavity with the opposite vertical walls under varying temperature differences. The natural convection of ZnO/DIW nanofluid was performed at Rayleigh number range of 7.45 × 10⁷ and 9.20 × 10⁸. Zeta potential values revealed stable nanofluids with no sedimentation of nanoparticles observed within 24 h. At 0.10 vol.% and temperature difference of 32 °C, the ZnO/DIW nanofluid was observed to enhance the heat transfer coefficient by 9.14% relative to DIW. Further increase in volume concentration resulted in the attenuation of heat transfer. Additionally, the Nusselt number and heat transfer rate were augmented by 8.42% and 6.75% at 0.10 vol.%, respectively.

摘要

公共领域充斥着关于腔内纳米流体的自然对流热传递性能的数值和实验结果的差异。本文介绍了矩形腔中去离子水 (DIW) 基氧化锌 (ZnO) 纳米流体的自然对流的实验研究。将 ZnO 纳米粒子 (20 nm) 分散在 DIW 中以配制各种体积浓度（0.10、0.18、0.36、0.50 和 1.0 vol.%）的纳米流体。分光光度计和zeta电位用于验证ZnO/DIW纳米流体在不同温度和浓度下的稳定性。在不同的温差下，ZnO/DIW 纳米流体和 DIW 被装入具有相对垂直壁的矩形腔中。ZnO/DIW 纳米流体的自然对流在 7.45 × 10 的瑞利数范围内进行⁷和 9.20 × 10 ⁸。Zeta 电位值显示稳定的纳米流体，在 24 小时内没有观察到纳米颗粒的沉淀。在 0.10 vol.% 和 32 °C 的温差下，观察到 ZnO/DIW 纳米流体相对于 DIW 提高了 9.14% 的传热系数。体积浓度的进一步增加导致传热衰减。此外，当体积为 0.10% 时，努塞尔数和传热率分别增加了 8.42% 和 6.75%。