ABSTRACT

This paper investigates the effect of the combined passive technique on heat transfer enhancement, friction factor, and thermal performance of a double-tube heat exchanger fitted with differently configured turbulators and using Alumina nanofluid. The performance parameters are studied for fixed flow rate (Re = 2500) of water at constant heat flux in the inner tube (hot fluid) and varying flow rates (500≤ Re≤5000) of Alumina nanofluid (volume concentrations: 0.05–0.15%) flowing in the outer tube (cold fluid). The configurations tested are a peripherally V-cut twisted tape (Twist Ratio = 20, 13.3, and 9.8) and a propeller turbulator (Number of propellers: 6, 8, and 10). The results show increased Nusselt number by 22.4% and 29.43%, increased Thermal Performance Factor by 1.25 and 1.33, respectively, for decreased twist ratio and increased number of propellers and volume concentration of Alumina nanofluid. The peripherally V-cut twisted tape (TR = 9.8) and propeller turbulator (Number of propellers = 10) with 0.15% volume concentrations of Alumina nanofluid combination give better performance, with a slight penalty in pressure drop. The correlations for the Nusselt number and friction factor are developed from the experimental data, which are fairly in good agreement with the experimental data.

摘要

本文研究了组合被动技术对装有不同配置的湍流器并使用氧化铝纳米流体的双管换热器的传热增强、摩擦系数和热性能的影响。研究了内管（热流体）中恒定热通量的水的固定流量（Re = 2500）和氧化铝纳米流体（体积浓度：0.05-0.15%）的变化流量（500≤Re≤5000）的性能参数) 在外管中流动（冷流体）。测试的配置是外围 V 形切割扭曲带（扭曲比 = 20、13.3 和 9.8）和螺旋桨扰流器（螺旋桨数量：6、8 和 10）。结果显示努塞尔数增加了 22.4% 和 29.43%，热性能系数分别增加了 1.25 和 1.33，用于降低捻比和增加螺旋桨数量和氧化铝纳米流体的体积浓度。具有 0.15% 体积浓度的氧化铝纳米流体组合的外围 V 形切割扭曲带 (TR = 9.8) 和螺旋桨湍流器（螺旋桨数量 = 10）提供更好的性能，但压降略有下降。努塞尔数和摩擦系数的相关性是从实验数据发展而来的，这与实验数据非常吻合。