CO2 Innenkühlung von spritzgegossenen GIT Bauteilen

This master thesis deals with the stages of development of a new process in order to improve the cooling efficiency of a gas injection process (GIT) with an overflow cavity. Despite the extra technical effort in tool usage the water injection technology (WIT) is favored over the traditional gas injection technology considering products with high heat removal. Therefore the primary purpose of this study is to analyze ways for a more efficient usage of the cooling potential of gases and to ultimately improve the cooling efficiency of the GIT. Following the Joule-Thomson effect, which says that the expansion of a gas leads to a physically valuable cooling effect, this phenomena is well discussed in this thesis. The cooling potential as well as the evocation of the effect heavily depends on the deployed gas and the ambient conditions. Regarding the surrounding conditions of a polymer injection process, carbon dioxide (CO2) proves to be an appropriate gas. Carbon dioxide is, however, much more soluble with several polymers than the generally used gas nitrogen (N2) and could lead to an expansion of the gas channel. This is why a combined usage of nitrogen and carbon dioxide is pursued. And as N2 has a very small potential of foaming up the gas channel, it is used to push the polymer melt in the overflow cavity, while CO2 is used for cooling during the flushing process. Based on a simulation with the open source CFD (Computational Fluid Dynamics) software OpenFOAM®, the essential process parameters for an efficient use of the Joule- Thomson effect is estimated. With the aid of the solvers and applications of OpenFOAM®, a simulation model is further created, which gives an insight into the most important process parameters.