Fundamental Analysis of Heat Transfer in Steel Scrap Preheating under Radiative and Convective Conditions

Abstract

Heat transfer in a preheating process of steel scraps was analyzed by taking convection combined with radiation into consideration. The analysis of simultaneous heat transfer has been carried out by experimental and mathematical methods. To examine the accuracy of calculation, the experiment was carried out in He, N₂ and Ar atmosphere under reduced, ambient and high pressure. The commercial FEM software ANSYS was used for simulation. The simulated results agreed well to the experimental ones with the specimen surface emissivities of 0.4. The convective heat transfer coefficient was estimated. The coefficient increased with increase in pressure and with decrease in temperature. The ratio of heat quantity between overall and convective heat -Ψ, is varied with the crucible temperature, and can be expressed by the following correlation:Ψ=βe^γT. The heat transfer coefficient can be summarized in the following dimensionless correlation:
Nu_ξ=2.62 Re_ξ^0.15