Design and Numerical Optimization of Gas Guidance System in Casting Silicon Furnace by the Orthogonal Experiment

Wenjia Su,Jiulong Li,Chen Li,Junfeng Wang,Wei Yang

doi:10.1007/s12633-021-01192-3

Abstract

3D global simulations were performed to investigate the gas flow and impurities transport in casting silicon furnace under the influence of a unique designed spray-type gas guidance system (GGS). The simulation results show that, the intensity of backflow at crucible outlet had no obvious change with the application of this GGS, but the flow area of backflow was effectively inhibited above the melt free surface and the kinetic rate of reaction was weakened at the cover. Finally, the area-average concentration of CO at the melt free surface was decreased by 31 %. The GGS was optimized by the orthogonal experiment, including the argon flow rate (Q), length of deflector (L) and distance between GGS and melt free surface (H). When Q = 40 L/min, H = 50 mm and L = 50 mm, the GGS had the most obvious effect on removing impurities.

Highlights

Multi-crystalline silicon and casting seed-assisted mono-crystalline silicon (CSAM-Si) grown by directional solidification (DS) method has dominated 61% of the photovoltaic market due to the low production cost and relative high conversion efficiency [1]
This study provides a possible way to produce high purity casting silicon ingot through the optimal design of the gas guidance system (GGS) in an industrial DS furnace for solar cell
Some part of argon gas ejected from the bottom outlet is first transported to the melt free surface and flee away from the crucible, which is identical to the traditional way

Summary

Introduction

Multi-crystalline silicon (mc-Si) and casting seed-assisted mono-crystalline silicon (CSAM-Si) grown by directional solidification (DS) method has dominated 61% of the photovoltaic market due to the low production cost and relative high conversion efficiency [1]. As the major impurities in crystalline silicon ingot, oxygen (O) and carbon (C) significantly affect the efficiency of silicon solar cells. Gao et al [5] found that the concentration of O and C in the new-type argon tube furnace could be reduced by shortening the distance between the cover and melt free surface. Teng et al [6, 7] showed that GGS could increase the gas velocity above melt free surface and reduce the concentration of SiO and CO. The argon backflow at crucible outlet and the chemical reaction on the cover can significantly increase the concentration of O and C impurities. This study provides a possible way to produce high purity casting silicon ingot through the optimal design of the GGS in an industrial DS furnace for solar cell

Orthogonal Experimental Design

Effects on flow pattern

Analysis of the orthogonal experiment

Conclusions

Conflict of Interest

Compliance with ethical standards