Twin screw pumps are used to transport gas-liquid mixtures in process technology. Nevertheless, a new cooling concept has to be developed for conveying mixtures with high gas content. An idea is to inject the liquid process fluid into the chambers of the pump. This method has a positive influence on the cooling effect and it also contributes to a better sealing of the gaps, hence, increasing the volume flow. At first, a transparent test rig, modeling one chamber of the pump with fluid injection, is designed to investigate the effect of the injection into the chamber of a twin screw pump. The test rig allows an analysis regarding the fluid dynamics in the gaps by varying the direction and number of injection.