EXPERIMENTAL AND NUMERICAL STUDY OF FORCED CONVECTION HEAT TRANSFER FROM AN INCLINED HEATED PLATE PLACED BENEATH A POROUS MEDIUM

للكاتبين :

A. R. EL-SHAMY*, R. Y. SAKR*, N. S. BERBISH*, AND M. H. MESSRA**

*Mech. Eng. Dept., Shoubra Faculty of Eng., Benha Univ., Egypt

**M.Sc. Student, Mech. Eng. Dept., Shoubra Faculty of Eng., Benha Univ., Egypt

ABSTRACT

The aim of the present work is an experimental and numerical study of forced convection heat

transfer from an inclined heated plate placed beneath a porous medium. The experiments were

carried out on an aluminum flat plate of 320 mm length, 140 mm width, and 6 mm thickness

and the plate was electrically heated with a uniform heat flux condition. The tested heated

plate was inclined on the flow direction with different angles of attack (α) varied from 0o

(horizontal position) to 30o, within a range of Reynolds number (based on the test plate

length) from 52000 to 171000. The porous media used in the experiments were made of PVC,

glass, and stainless steel materials, covering a wide range of solid thermal conductivities. The

nominal sphere diameter of all used materials was nearly about 12 mm, and the porosity of

the porous media was about 0.52. Also, the present problem was solved numerically using a

commercial CFD code. Two cases have been investigated; flat plate without porous media

and with porous media. Both cases were solved in two dimensions. The case of smooth plate

without porous media utilized the standard k-ε model to model the flow of air over the plate,

but the laminar model was used to predict the case of plate with porous media. For plate with

or without porous medium and the same inclination angle, the experimental results showed

that the heat transfer coefficient was increased with increasing the Reynolds number. Also, it

was found that the heat transfer coefficient was increased with increasing the inclination

angle, and was reached the maximum enhancement ratio at inclination angle of 20o and with

further inclination of the heating plate (20o < ≤ 30o), the heat transfer coefficient was

slightly decreased. Moreover, it was observed that the existence of the packed bed increases

the heat transfer coefficient. In addition, for a constant particle size, higher heat transfer

coefficients were obtained with higher particle thermal conductivity (steel spheres). For

smooth inclined plate without porous medium, the maximum average Nusselt number

enhancement ratio (average Nusselt number of the inclined smooth plate/average Nusselt

number of the horizontal smooth plate without porous media), Nusm / Nuo , was about 1.239

and was obtained at = 20o and Re = 71927. Also, for the inclined plate with porous medium,

the maximum enhancement ratio of the average Nusselt number ( Nup / Nuo ) was about 3.10.

This value was obtained at = 20o, Re=71927, and using stainless steel spheres porous

medium. Good agreement was observed between the experimental data and the numerical

results that obtained from the models in the range of (0o ≤ ≤ 20o) and for the all range of

Reynolds number used in this study. Finally, empirical correlation for the average Nusselt

number was obtained utilizing the present experimental data as a function of the Reynolds

number, the inclination angle (angle of attack), and the thermal conductivity of the packing

material.

اترك تعليقاً

لن يتم نشر عنوان بريدك الإلكتروني. الحقول الإلزامية مشار إليها بـ *