The study of compound heat transfer enhancement technique using dual counter twisted tapes (DCTs) together with TiO/water nanofluids was carried out. The dual twisted tapes in form of arrangement were utilized at three twist ratios ( = 1.5, 2.0 and 2.5). TiO/water nanofluids having three different volume concentrations ( = 0.05, 0.10 and 0.15 %) were employed as the testing fluids. The results indicated that heat transfer rate, friction factor and thermal enhancement index rose with decreasing tape twisted ratio and elevating nanofluid concentration. The TiO/water nanofluids applied in the present work offered higher than pure water (the base fluid) by 7.3–10.0 %. The application of DCT with the smallest of 1.5 and TiO/water nanofluids with the largest of 0.15 vol% led to the highest thermal enhancement index (TEI) of 1.53, under the same pumping power criteria. Additionally, the k-nearest neighbor (k-NN) and artificial neural network (ANN) were developed to predict the thermal enhancement index (TEI). It was found that the k-NN and ANN models provided maximum R values of 0.919 and 0.992 f, respectively.

中文翻译：

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双反扭曲带管内二氧化钛/水纳米流体热性能增强的参数研究

采用双反扭带（DCT）与 TiO2/水纳米流体复合强化传热技术进行了研究。排列形式的双绞带以三种绞合比（=1.5、2.0和2.5）使用。采用具有三种不同体积浓度（= 0.05、0.10 和 0.15%）的 TiO2/水纳米流体作为测试流体。结果表明，传热速率、摩擦因数和热增强指数随着胶带绞合比的减小和纳米流体浓度的升高而升高。本工作中应用的 TiO2/水纳米流体比纯水（基础流体）高 7.3-10.0%。在相同的泵浦功率标准下，最小为 1.5 的 DCT 和最大为 0.15 vol% 的 TiO2/水纳米流体的应用导致最高的热增强指数（TEI）为 1.53。此外，还开发了 k 最近邻 (k-NN) 和人工神经网络 (ANN) 来预测热增强指数 (TEI)。结果发现，k-NN 和 ANN 模型提供的最大 R 值分别为 0.919 和 0.992 f。