Untersuchung von Stofftransportmechanismen und Konvektion in einem Vertical Gradient Freeze Ofen zur Siliziumerstarrung Zusammenfassung: The following works is the elucidation of fundamental transport processes in a furnace atmosphere and the understanding of the kinetics of the melt and atmosphere taking into account the supply of argon. Simulations were compared with experimental result. The used model system was a vertical gradient freeze (VGF) furnace from the company PVA TePla. It is a prototype of an ingot solidification system for multi crystalline solar silicon for crucible sizes up to 250 Kg. To minimize scaling effects a system of industry equivalent size was chosen. As a tool for mapping the internal processes Computational Fluid Dynamics (CFD) simulation program Fluent was used. The efficiency of photovoltaic energy conversion among other things depends on the material. The further improvement of the raw material (wafer material) is a major goal. For this reason in this work crystallization processes were modeled by numerical simulations