Experimental study on the behavior of the two phase flow shock waves occurring in the ejector refrigeration cycle

Abstract

Conservation of energy is becoming increasingly important for the protection of the environment. Improving the efficiency of a refrigeration cycle is a critical factor to achieve this goal. Recently, an ejector system was developed that reduces the energy requirements of the compressor in the refrigeration cycle. Two-phase-flow shock waves appear in the ejector under certain operating conditions and increase the pressure difference between suction inlet and outlet. Such shock waves play an important role in the ejector’s compression mechanism and thus merit a thorough investigation. In this work, we visualize the structure of a two-phase-flow shock wave in an ejector nozzle using a high-speed camera to monitor an optical beam transmitted through a refrigerant (hot water). As the pressure rises in the ejector outlet, the shock wave moves from the outlet to the nozzle throat and changes from an oblique shock wave to a normal shock wave. The shape of the output nozzle may modify the structure of the shock waves.

Keywords

• multiphase flow
• supersonic flow
• shock waves
• visualization
• ejector