Purpose

Using passive techniques like twisted tapes and corrugated surface is an efficient method of heat transfer improvement, since the referred manners break the boundary layer and improve the heat exchange. This paper aims to present an improved dual-flow parabolic trough collector (PTC). For this purpose, the effect of an absorber roof, a type of turbulator and a grooved absorber tube in the presence of nanofluid is investigated separately and simultaneously.

Design/methodology/approach

The FLUENT was used for solution of governing equation using control volume scheme. The control volume scheme has been used for solving the governing equations using the finite volume method. The standard k–e turbulence model has been chosen.

Findings

Fluid flow and heat transfer features, as friction factor, performance evaluation criteria (PEC) and Nusselt number have been calculated and analyzed. It is showed that absorber roof intensifies the heat transfer ratio in PTCs. Also, the combination of inserting the turbulator, outer corrugated and inner grooved absorber tube surface can enhance the PEC of PTCs considerably.

Originality/value

Results of the current study show that the PTC with two heat transfer fluids, outer and inner surface corrugated absorber tube, inserting the twisted tape and absorber roof have the maximum Nusselt number ratio equal to 5, and PEC higher than 2.5 between all proposed arrangements for investigated Reynolds numbers (from 10,000 to 20,000) and nanoparticles [Boehmite alumina (“λ-AlOOH)”] volume fractions (from 0.005 to 0.03). Maximum Nusselt number and PEC correspond to nanoparticle volume fraction and Reynolds number equal to 0.03 and 20,000, respectively. Besides, it was found that the performance evaluation criteria index values continuously grow by an intensification of nanoparticle volume concentrations.

中文翻译：

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纳米流体对双流槽式集热器性能的影响伴随着使用实验数据的被动技术

 目的

使用扭曲带和波纹表面等被动技术是改善传热的有效方法，因为所引用的方式会打破边界层并改善热交换。本文旨在提出一种改进的双流槽式集热器 （PTC）。为此，在纳米流体存在下，分别研究了吸收器顶部、一种湍流器和带槽吸收管的影响。

设计/方法/方法

FLUENT 用于使用控制体积方案求解控制方程。控制体积方案已用于使用有限体积法求解控制方程。已选择标准的 k-e 湍流模型。

 发现

已经计算和分析了流体流动和传热特征，如摩擦系数、性能评估标准 （PEC） 和努塞尔数。结果表明，吸收器屋顶增强了 PTC 中的传热比。此外，插入湍流器、外部波纹和内槽吸收管表面的组合可以显着提高 PTC 的 PEC。

 原创性/价值

当前研究的结果表明，具有两种传热流体的 PTC，外表面和内表面波纹吸收管，插入扭曲带和吸收器屋顶，其最大努塞尔数比等于 5，并且 PEC 高于 2.5，在所有拟议的雷诺数排列之间研究的雷诺数（从 10,000 到 20,000）和纳米颗粒 [勃姆石氧化铝 （“λ-AlOOH）”] 体积分数（从 0.005 到 0.03）。最大努塞尔数和 PEC 对应于纳米颗粒体积分数和雷诺数分别等于 0.03 和 20,000。此外，研究发现性能评价标准指数值随着纳米颗粒体积浓度的加剧而持续增长。