Abstract
A packed bed model was used to clarify fundamental conditions on the heat transfer in a preheating zone of cupola. The apparatus consisted of a cylinder 160mm in inner diameter installed with iron grating on which a layer of steel ball packed bed 100 to 200mm in thickness had been charged. Steel balls were 20 to 40mm in diameter. Hot gas was blown into the bed from the bottom at flow rates 4 and 6m/s. The diameter of balls has the most significant effect on heat absorption of the bed. The heat is accumulated in the bed faster as the ball diameter is smaller and a difference of temperatures of balls and gas is rapidly lost. The heat transfer coefficient h is represented as : h = W0.83 T0.3/D1.03 where W is flow rate, T gas temperature and D ball diameter. The values by the use of this equation are in good agreement with those in other works.
