Energy and heat transfer analysis on the heating process of crude oil tank with mechanical stirring

Taking into account the characteristics of non-Newtonian fluids and the influence of latent heat of wax crystallization, this study establishes physical and mathematical models for the synergy of tubular heating and mechanical stirring during the waxy crude oil heating process. Numerical calculations are conducted using the sliding grid technique and FVM. The focus of this study is on the impact of stirring rate (τ), horizontal deflection angle (θ₁), vertical deflection angle (θ₂), and stirring diameter (D) on the heating effect of crude oil. Our results show that as τ increases from 200 rpm to 500 rpm and D increases from 400 mm to 600 mm, there is an improvement in the average crude oil temperature and temperature uniformity. Additionally, heating efficiency increases by 0.5% and 1%, while the volume of the low-temperature region decreases by 57.01 m³ and 36.87 m³, respectively. As θ₁ and θ₂ increase from 0° to 12°, the average crude oil temperature, temperature uniformity, and heating efficiency decrease, while the volume of the low-temperature region remains basically the same. Grey correlation analysis is used to rank the importance of stirring parameters in the following order: τ>θ₁>θ₂>D. Subsequently, multiple regression analysis is used to quantitatively describe the relationship between different stirring parameters and heat transfer evaluation indices through equations. Finally, based on entropy generation minimization, the stirring parameters with optimal heat transfer performance are obtained when τ = 350 rpm, θ₁ = θ₂ = 0°, and D = 500 mm.