- This paper presents cooling by natural and induced convection of a vertical cylinder and a horizontal array of vertical cylinders in a narrow enclosed space with openings. A laboratory-scale model was studied both experimentally and numerically. The cylinders were 100 mm high and 50mm in diameter. Cartridge heaters were installed in drills along the cylinder axis and connected to an external power source. The cylinders were positioned in a horizontal enclosure which was a box of an inner cross-section of 125mm (height) by 100mm (width). The length of the box was varied with the number of cylinders used, or with the spacing between the cylinders. Temperature was measured at various locations inside the cylinders by fine thermocouples using a multi-channel data acquisition unit. The experiments were performed for one to eight cylinders with various spacing. Numerical simulations were performed for the velocity and temperature fields inside the enclosure, using the Fluent 5.5 software. Both convection and radiation inside the enclosure were accounted for. Effect of various parameters of the system, including the enclosure width, height and the cylinders spacing, on the cylinder temperature has been studied. Comparison of the experimental results with numerical predictions is presented and discussed.