Experimental and Numerical Investigation of Natural Convection Heat Transfer in an Inclined, Outer Cylinder Heated Concentric Annulus

Yasin K. Salman, Mustafa Z. Gheni


Natural convection heat transfer in an open inclined concentric annulus with the outer cylinder subjected to a constant heat flux while the inner cylinder unheated was investigated experimentally and numerically. For the steady state condition, the investigation focuses on the effect of annulus inclination angle and the outer cylinder heat flux on heat transfer process. Heat transfer results are given for inclination angles of 0o (horizontal), 30o,400, 60o and 90o using concentric annulus with diameter ratio of 1.8, length 500 mm and heat fluxes varied from 70 W/m2 to 600W/m2. The mathematical model was solved numerically using finite element software (COMSOL Multi Physics4.0 b), with the same annulus geometrical dimension and boundary conditions which have been covered by experimental work. After finding the numerical results, the validation between experimental and numerical results has been verified. A good agreement has been found between the experimental and the numerical results. The results showed that the local and average Nusselt number increase as the heat flux increase and when angle of inclination changed from 0o to 90o. Empirical correlations of average Nusselt number as a function of average Rayleigh number were deduced.

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