Comprehensive hydrothermal analysis of an inclined mini-channel with fin array: by dual/multi-relaxation-time LBM and experimental process on SiO₂-glycol rheological/thermal characteristics

Abstract

Purpose

The purpose of this study is to present a comprehensive hydrothermal analysis on an inclined mini-channel using numerical and experimental techniques. The fin array acts as heat source within the channel, and a wavy wall located at the top of the channel is heat sink. The side walls are insulated with curved profiles. Also, the channel is inclined with four known inclination angles. To solve the governing equations, the dual-multi-relaxation-time lattice Boltzmann method with D2Q9 and D2Q5 lattice models for flow and temperature fields is used, respectively. Also, the channel is filled with SiO2-glycol nanofluid.

Design/methodology/approach

Identifying the behavior of a thermal component during natural convective flow is a challenging topic due to its complexities. This paper focuses on analyzing the thermal and hydrodynamic aspects of a narrow channel equipping with fin array.

Findings

Two correlations are proposed considering temperature and volume fraction ranges for thermal conductivity and dynamic viscosity according to measured experimental data which are used in the numerical phase. Finally, the structure of flow, temperature distribution of fluid, local thermal and viscous dissipations, volume-averaged entropy production, Bejan number and heat transfer rate are extracted by numerical simulations. The results show that the average Nusselt number enhances about 57% (maximum enhancement percentage) when volume fraction increases from 1% to 3% at Ra = 10⁶ and θ = 90°. In addition, the value of entropy generation is maximum at φ = 1%, Ra = 10⁶ and φ = 90°. Also, the maximum enhancement of entropy generation in range of Ra = 103 to 106 is about 4 times at φ = 1% and θ = 90°.

Originality/value

The originality of the present study is combining a modern numerical method (i.e. dual/multi-relaxation-time LBM) with experimental observation on characteristics of SiO₂-glycol nanofluid to study the thermal and hydrodynamic properties of the studied mini-channel.

Citation

Kamali, D., Hejri, S., Akbar, N. and Hasani Malekshah, E. (2021), "Comprehensive hydrothermal analysis of an inclined mini-channel with fin array: by dual/multi-relaxation-time LBM and experimental process on SiO₂-glycol rheological/thermal characteristics", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 31 No. 7, pp. 2405-2429. https://doi.org/10.1108/HFF-08-2020-0527