HEAT TRANSFER BETWEEN A ROTATING CYLINDER AND A TRANSPORTED PLATE

摘要

The local heat transfer between a rotating cylinder and an endless metal strip transported above it was determined experimentally. For this purpose typical rollers of different materials used in industrial kilns were heated electrically from the inside. The strip made of steel alloy had a thickness of 100 μm. The temperature increase on the upper side of the strip during the movement above the roller was measured without contact using a thermal infrared camera. The distance between the roller and the strip was adjusted between 0 and 1.5 mm. The local heat transfer coefficient can be described by the equation α = λ_g/(δ_(id) + δ_(ad) + I), where λ_g is the thermal conductivity of the gas, δ_(id) is the gap width in case of ideal contact, δ_(ad) is an additional distance dependent on the kind of roller, and I is a modified free path length of the gas.