Purpose

The purpose of this study is analysis of the natural convection and entropy production in a two-dimensional section of the considered heat exchanger. For this purpose, the lattice Boltzmann method which is equipped with Bhatnagar–Gross–Krook model is used. This model proposes a significant accurate prediction for thermal and hydro-dynamical behaviors over free convection phenomenon. The heat exchanger is filled with Fe₂O₃-water nanofluid. To improve the accuracy of prediction, it is neglected to use the theoretical models for properties of nanofluid. At this end, some experimental observations are conducted, and the required rheological and thermal properties of nanofluid are measured based on laboratory work..

Design/methodology/approach

The present work focuses on the influence of different factors on the thermal behaviors and entropy production of a heat exchanger. The heat exchanger is consisted by an inner tube, an outer tube and some fins which are implanted at the surface of inner tube.

Findings

The effects of various factors like structure of inner fins, nanoparticle concentration and Rayleigh number over the heat transfer rate, local and volumetric entropy production, Bejan number, flow configuration and temperature distributions are provided.

Originality/value

The originality of this work is using a new-developed numerical method for treating natural convection and experimental measurements for thermal and rheological properties of nanofluid.

中文翻译：

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使用 Bhatnagar-Gross-Krook Lattice Boltzmann (BGKLBM) 和 Fe2O3-水的流变-热行为对翅片/管式换热器进行实验/数值热液第二定律分析

目的

本研究的目的是分析所考虑的换热器二维截面中的自然对流和熵产生。为此，使用了配备 Bhatnagar-Gross-Krook 模型的格子 Boltzmann 方法。该模型对自由对流现象的热和流体动力学行为提出了重要的准确预测。热交换器充满Fe ₂ O _{3 -}水纳米流体。为了提高预测的准确性，忽略了使用纳米流体特性的理论模型。为此，进行了一些实验观察，并在实验室工作的基础上测量了纳米流体所需的流变和热性能。

设计/方法/方法

目前的工作重点是不同因素对换热器的热行为和熵产生的影响。换热器由内管、外管和一些植入内管表面的翅片组成。

发现

提供了各种因素（如内翅片结构、纳米粒子浓度和瑞利数）对传热速率、局部和体积熵产生、Bejan 数、流动配置和温度分布的影响。

原创性/价值

这项工作的独创性是使用新开发的数值方法来处理自然对流和纳米流体的热和流变特性的实验测量。