THE INFLUENCE OF INCLINATION ANGLE ON NATURAL CONVECTION IN A RECTANGULAR ENCLOSURE

An experimental work was conducted to investigate the influence of inclination angle on natural heat transfer in a rectangular enclosure. The enclosure length was (100 cm) with a square cross section (10×10 cm). All the enclosure surfaces were insulated except the upper surface, where half of it was cooled and the other half washeated. The tests were done for three inclination angles (15o, 45o and 75o), three mass flow rates (0, 0.0275 and 0.062 kg/sec) and five heat fluxes (4.92, 19.2, 39.96, 69.6 and 108 W/m2) for (1.95×105 ≤ Ra ≤ 4.96×106). It was found that the highest Nux was at (x/L=0.33) where the highest heat transfer occurred between the hot air and the cold surface (high temperature difference). It was also found that as the inclination angle increased, the Nux and Nu increased. This is because the falling cold air disrupted the rising hot air which led to anincrease in the heat transfer between the hot air and the cold surface. Increasing the mass flow rate and the heat fluxes had increased the heat transfer through the enclosure. A correlation was proposed to relate Nu with Ra and the inclination angle.A good agreement was found when comparing the experimental data and the present correlation with a previous work.