Continuous annealing is an efficient process to provide a sound heat treatment on strip materials with higher quality, faster delivery, and higher thermal efficiency than conventional batch annealing. This process is done to improve the physical and mechanical properties of strips after cold rolled. Despite direct measurement of the final temperature of the strip by a pyrometer, an accurate estimation of the strip temperature along the continuous annealing furnace is the main concern to guarantee the quality of the strip material produced. The present study investigates the temperature distribution from a strip passing through the heating zone of continuous annealing furnace. It would be helpful to establish a physical model to simulate the thermal process taking place in the furnace and then to gain a deeper insight into the detailed mechanisms of heat transfer between components. For this purpose, a suitable mathematical model has been suggested to predicate the distribution of the strip temperature for both one dimentional and tree dimentional cases. Both the direct and indirect contact temperature measurements are difficult to implement due to serious restrictions regarding the concerns of safety operation and complicated radiation interaction between several surfaces in the furnace. Therefore the scale of the model accuracy is only the produced temperature. At first a suitable numerical method has been chosen for solving the energy equation. Then the mechanisms of heat transfer in furnace, including free, force convection and radiation, has been investigated. The main heat transfer to strip is by radiation. To derermine the boundary condition of radiation, considering the furnace geometry and the existence of the radiand tubes as the heat source, the Monte Carlo method has been studied and applied to determine the configuration factors in the whole furnace. The results from the mathematical model designed for this process have been compared against real data from annealing furnace in galvanizing line of Mobarakeh Steel Complex. The slight error of model, indicates the capability of the model in predicating the temperature distribution of strip in furnace. The results show that despite spending too much time and money, three dimentional solution has little effect on the accurancy of the results. Due to the accurate calculation of the configuration factors by Monte Carlo method, one dimensional solution offers more accurate answer. Also the results obtained from Monte Carlo solution for calculating the view factor for strip elements to walls in furnace and radiant tubes is presented for suitable number of rays and the length of strip. In addition the effect of the various parameters such as load emissivities, load velocities and load thicknesses on the strip temperature distribution, has been investigated. Once the accuracy and reliability of this simulation model are validated through experimentation, the model could be used to adjust the operational parameters to obtain the desired existing strip temperature. Keywords: Continuous annealing, Galvanizing line, Mathematical model, Mont Carlo method, Radiant tube.
