| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 103 === Two 3-D mathematical transient heat transfer models for the prediction of temperature distribution within the slab has been developed by considering the thermal radiation in the reheating furnace. The slabs are heated through non-firing, preheating, 1st-heating, 2nd-heating, and soaking zones, respectively. There are two physical models considered in this thesis. (1) model 1: there is no combustion, only thermal radiation is considered and the wall temperature is function of time (2) model 2: includes the burners, and combustion/radiation/convection are all considered. Model 2 is used to check accuracy of mode l. Comparison with the in-situ experimental data from Steel Company in Taiwan shows that the present heat transfer model works well for the prediction of thermal behavior of the slab. The results showed when the skid button height is 60mm, 90mm, and 120mm, respectively, the temperature difference between the upper and lower surfaces is 42.8K, 38.0K, and 34.4K. It means the skid mark can be improved by increasing the height of the skid button. And the numerical predictions of the slab temperature error are less than 10% compared with those of experimental data. Is shown that model 1 is reasonable because the radiation heat transfer dominates the heating process. The results showed the thermal contact resistance can slightly improve the effects of the skid mark. In the last part, the results showed that when the gap distance is 50mm, 75mm, and 100mm, respectively, the edge surfaces temperature difference between the upper and lower surfaces is 67.2K, 62.2K, and 58.2K. It means that the effect of gap distance is important only for the edge surfaces. And the bigger gap distance can effectively improve the slab skid mark
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