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NUMERICAL INVESTIGATION OF NATURAL CONVECTION HEAT TRANSFER IN A PARALLELOGRAMIC ENCLOSURE HAVING AN INNER CIRCULAR CYLINDER USING LIQUID NANOFLUID

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a Department of Chemical Engineering and Petroleum Industries, Al-Mustaqbal University College, Babylon, 51001, Iraq
b Air conditioning and Refrigeration Techniques Engineering Department, Al-Mustaqbal University College, Babylon, 51001, Iraq

* Corresponding Author: Email:

Frontiers in Heat and Mass Transfer 2019, 12, 1-14. https://doi.org/10.5098/hmt.12.2

Abstract

Fluid flow and natural convection heat transfer in a parallelogram enclosure with an inner circular cylinder using Cu-water nanofluid are studied numerically. Dimensionless Navier-Stokes and energy equations are solved numerically using finite element method based two-dimensional flow and steady-state conditions. This study evaluates the effect of different concentrations of Cu-water nanofluids (0% to 6%) with different Rayleigh numbers 10³ ≤ Ra ≤ 10⁶ under isotherm wall temperatures. The effects of geometrical parameters of the parallelogram enclosure (inclination angle in range of 0 ≤ α ≤ 30 and location of inner circular cylinder -0.2 ≤ H ≤ +0.2 on the flow field and heat transfer are examined. The results are presented in terms of streamlines, isotherms, local and average Nusselt number. It is found that the inclination angle has a significant effect on flow pattern and heat transfer and the inclination angle of 30o at a vertical location H=-0.2 gives better fluid flow strength. Moreover, the maximum heat transfer enhancement is obtained when the circular cylinder moves vertically downward up to H=-0.1 and the inclination angle is 30o . The results also indicate that as the Rayleigh number, nanofluid concentration increase, the rate of heat transfer will increase.

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