A CFD analysis of the flow structure inside a steam ejector to identify the suitable experimental operating conditions for a solar-driven refrigeration system

• We identify the suitable experimental conditions for a solar-driven refrigeration system.
• We model the flow structure and the mixing process inside a steam ejector using CFD.
• We examine the effect of varying the operating pressures on the entrainment ratio.
• Two distinct shock waves occurred in the diffuser section low condenser pressures (<2.5 kPa).

This paper presents a numerical study of a steam ejector using CFD with the objective of identifying suitable experimental conditions that allows for a reliable ejector cycle operation. The flow structure and the mixing process inside the ejector were assessed for a range of operating conditions typical for a solar driven air conditioning system. The effect of varying the condenser pressure was studied. It was found that for relatively low condenser pressures (<2.5 kPa), two distinct shock waves occurred in the diffuser section resulting in a reduced re-compression efficiency, although it did not have a direct impact on the entrainment ratio. The effect of generator pressure was also studied. It was found that the entrainment ratio showed a maximum for constant condenser conditions. A near optimal condition of 70 kPa generator and 3 kPa condenser pressures were identified and tested in a preliminary experiment carried out with the solar driven ejector system installed in Tunis.