The temperature uniformity within U-style silicon located in a novel 80-rod siemens reactor with a high silicon core

The previous studies focus on simplified reactor configurations with 12 or 24 pairs of rods and do not account for the complex thermal and electrical behaviors and multi-ring interaction present in a large-scale reactor. This study developed an electric heating model for a novel four-ring, 80-rod industrial Siemens reactor with U-style silicon. This paper investigated the effects of direct current (DC) and alternating current (AC) heating on the thermal and electrical performances of a polysilicon reduction furnace. The primary objective is to achieve a more uniform temperature distribution between the center and surface of the U-style silicon. The results indicate that the temperature gradient within the U-style silicon is the maximum under DC heating, with the highest temperature in the center. In contrast, AC heating significantly improves temperature uniformity. The temperature gradient and center temperature significantly decrease as the frequency increases due to the enhanced skin effect, which reduces the contribution of Joule heating in the central region. An interaction correlation is observed between AC frequency and the diameter of U-style silicon in the range of 5–200 kHz. The skin effect appears more rapidly as the diameter of U-style silicon increases, lowering the critical frequency and thereby enhancing control over the thermal field. Furthermore, obtained the regression equation to predict the temperature difference (ΔT) with high accuracy, exhibiting an average relative error of only 4.62 % and an R² of 0.99. The results offer valuable insights for optimizing heating methods to improve thermal efficiency in the production process of polysilicon.