Purpose

The purpose of this paper is to investigate the effects of geometrical parameters, eccentricity and perforated fins on natural convection heat transfer in a finned horizontal annulus using three-dimensional lattice Boltzmann flux solver.

Design/methodology/approach

Three-dimensional lattice Boltzmann flux solver is used in the present study for simulating conjugate heat transfer within an annulus. D3Q15 and D3Q7 models are used to solve the fluid flow and temperature field, respectively. The finite volume method is used to discretize mass, momentum and energy equations. The Chapman–Enskog expansion analysis is used to establish the connection between the lattice Boltzmann equation local solution and macroscopic fluxes. To improve the accuracy of the lattice Boltzmann method for curved boundaries, lattice Boltzmann equation local solution at each cell interface is considered to be independent of each other.

Findings

It is found that the maximum heat transfer rate occurs at low fin spacing especially by increasing the fin height and decreasing the internal-cylindrical distance. The effect of inner cylinder eccentricity is not much considerable (up to 5.2% enhancement) while the impact of fin eccentricity is more remarkable. Negative fin eccentricity further enhances the heat transfer rate compared to a positive fin eccentricity and the maximum heat transfer enhancement of 91.7% is obtained. The influence of using perforated fins is more considerable at low fin spacing although some heat transfer enhancements are observed at higher fin spacing.

Originality/value

The originality of this paper is to study three-dimensional natural convection in a finned-horizontal annulus using three-dimensional lattice Boltzmann flux solver, as well as to apply symmetry and periodic boundary conditions and to analyze the effect of eccentric annular fins (for the first time for air) and perforated annular fins (for the first time so far) on the heat transfer rate.

中文翻译：

---

使用三维格子 Boltzmann 通量求解器研究几何参数、偏心距和穿孔翅片对水平翅片环中自然对流热传递的影响

目的

本文的目的是使用三维格子 Boltzmann 通量求解器研究几何参数、偏心距和穿孔翅片对水平翅片环中自然对流换热的影响。

设计/方法/方法

三维晶格玻尔兹曼通量求解器在本研究中用于模拟环内的共轭传热。D3Q15 和 D3Q7 模型分别用于求解流体流动和温度场。有限体积法用于离散质量、动量和能量方程。Chapman-Enskog 展开分析用于建立晶格 Boltzmann 方程局部解与宏观通量之间的联系。为了提高曲线边界的格子玻尔兹曼方法的精度，每个单元界面的格子玻尔兹曼方程局部解被认为是相互独立的。

发现

发现最大传热率发生在小翅片间距时，尤其是通过增加翅片高度和减小内部圆柱距离。内筒偏心的影响不大（最多提高5.2%），而翅片偏心的影响更为显着。与正翅片偏心相比，负翅片偏心进一步提高了传热率，并且获得了 91.7% 的最大传热增强。尽管在较大的翅片间距下观察到了一些传热增强，但在较小的翅片间距下使用穿孔翅片的影响更为显着。

原创性/价值

本文的独创性是使用三维格子玻尔兹曼通量求解器研究带翅片水平环面的三维自然对流，并应用对称性和周期性边界条件，分析偏心环翅片的影响（对于空气的第一次）和穿孔环形翅片（迄今为止的第一次）对传热率的影响。