Convective heat transfer performances of dilute metal oxide suspensions in D.I water (Deionized water) flowing through a VUV (Vacuum Ultraviolet) surface tuned mini channel with a hydraulic diameter of 3 mm were quantified in this work. The experiment was carried out first on a channel with untreated PDMS coating with a contact angle of 86.2 ± 2.7° and then with a VUV treated PDMS channel having a contact angle of 2.7 ± 2.1°. Mach-Zehnder interferometry, a non-intrusive measurement technique, was employed to conduct fringe analysis in the test channel. Modified Naylor – Duarte method was used to quantify the heat transfer coefficients in the minichannels. Experiments conducted using alumina and silica nanofluids were compared with D.I water in both channels. The experiments were carried out at three different heat inputs (5 W, 10 W, and 15 W) and three other Reynolds numbers (294, 591, and 855). At Re = 294 and 5 W of heat input, the highest volume fraction of alumina nanofluid in VUV treated minichannel recorded a 5.92 ± 1.9% increment in heat transfer rates compared to the same charge in untreated minichannel. For the same flow conditions in VUV treated minichannels, 0.02 vol% alumina nanofluid recorded a 20.11 ± 3.4% increment in heat transfer rates than D.I water, while it was 6.11 ± 2.7% for 0.02 vol% of silica nanofluids. In the VUV treated minichannel at 5 W and Re = 294, the boundary layer thickness showed a reduction of 9.64 ± 1.6% for 0.02 vol% alumina nanofluid, as compared to the untreated channel. But at Re = 855, the percentage enhancement in heat transfer was confined to 1.74% for all test fluids in surface tuned minichannel. It was found that the heat transfer in the VUV treated minichannel was superior compared to that in the untreated minichannel at lower Reynolds number (Re = 294). The results showed that alumina nanofluids performed significantly better than silica nanofluids at a given concentration in both minichannels. The plausible reasons for the enhancement in heat transfer rates in VUV treated minichannels are also discussed.

在这项工作中，量化了流动通过水力直径为 3 毫米的 VUV（真空紫外线）表面调谐微型通道的去离子水（去离子水）中的稀金属氧化物悬浮液的对流传热性能。该实验首先在接触角为 86.2 ± 2.7° 的未处理 PDMS 涂层的通道上进行，然后在接触角为 2.7 ± 2.1° 的 VUV 处理的 PDMS 通道上进行。Mach-Zehnder 干涉测量法是一种非侵入式测量技术，用于在测试通道中进行条纹分析。改进的 Naylor – Duarte 方法用于量化微通道中的传热系数。使用氧化铝和二氧化硅纳米流体进行的实验与两个通道中的去离子水进行了比较。实验在三种不同的热输入下进行（5 W、10 W、和 15 W）和其他三个雷诺数（294、591 和 855）。在Re  = 294 和 5 W 的热输入，VUV 处理的微通道中氧化铝纳米流体的最高体积分数与未处理的微通道中的相同电荷相比，传热速率增加了 5.92 ± 1.9%。对于 VUV 处理的微通道中相同的流动条件，0.02 vol% 的氧化铝纳米流体记录的传热率比去离子水高 20.11 ± 3.4%，而 0.02 vol% 的二氧化硅纳米流体则为 6.11 ± 2.7%。在 5 W 和Re  = 294的 VUV 处理的微通道中，与未处理的通道相比，0.02 vol% 氧化铝纳米流体的边界层厚度减少了 9.64 ± 1.6%。但在Re = 855，对于表面调谐微通道中的所有测试流体，传热的百分比增强被限制在 1.74%。发现在较低雷诺数 ( Re  = 294)下，经 VUV 处理的微通道中的传热优于未处理的微通道中的传热。结果表明，在两个微通道中，氧化铝纳米流体在给定浓度下的性能明显优于二氧化硅纳米流体。还讨论了 VUV 处理的微通道中传热率提高的合理原因。