Numerical Study of Heat Transfer Enhancement in an Inclined Rectangular Channel with Multiple Discrete Heaters through Active Flow Modulation.

The interaction between the fluid flow in a channel and transversely rotating cylinders across the flow field has a great impact on heat transfer rate. The purpose of this study is to investigate numerically the heat transfer enhancement from multiple discrete heaters placed in an inclined rectangular channel with rotating cylinders inserted above each of the heaters. The whole computation was analyzed for a 2D rectangular channel with upper wall is maintaining a constant low temperature and the bottom wall is provided with multiple discrete isoflux flat heaters connected by adiabatic segments. At inlet, a fully developed parabolic velocity profile at constant low temperature has been induced. Air has been considered as working fluid. The system has been represented mathematically by different sets of governing equations, which are solved by using Galerkine Finite Element method. The effect of the variation of rotating speeds of the cylinders in terms of the cylinder peripheral speed to maximum inflow velocity (ξ), Grashof number (Gr) and channel inclination angle (α) were numerically investigated for the range of 103 ≤ Gr ≤ 10⁶, 0° ≤ α ≤ 90°, 0.5 ≤ ξ ≤ 2.0 at fixed Reynolds number, Re = 100. Temperature field and flow field are investigated in terms of isotherm lines (θ) and stream lines (Ψ) respectively. Heat transfer characteristics are also demonstrated in terms of Normalized Nusselt number (Nu/Nunc) and Local Nusselt number (Nul). The results reveal that insertion of rotating cylinders above heaters increases heat transfer rate from 32% to 55% for all speed ratios (ξ) for the values of Grashof number 103≤ Gr ≤ 105 and then start to decrease but still remains about 12% to 22% higher than no cylinder condition at Gr = 10⁶. [ABSTRACT FROM AUTHOR]