Description

The present problem simulates a steam ejector with gas methane fluid in ANSYS Fluent software. A steam ejector is a kind of mechanical device that transforms motive fluid pressure energy into velocity energy by means of the Venturi effect of converging-diverging nozzles.  The ejector's converging segment allows the high-speed methane gas to pass through while its pressure drops. A mixing zone is produced when the methane gas comes into contact with the suction fluid in the throat. After that, the blended fluids move through the diverging portion, where the high-velocity fluid slows down and returns pressure energy to velocity energy.

The 2D geometry of the model is created in Design Modeler software and the meshing is done in ANSYS Meshing creating 11,132 elements.

Methodology

The primary objective of this simulation study is to understand the performance and operational characteristics of a steam ejector, specifically focusing on the interaction between methane gas and air within the system. A density-based solver is employed for this simulation due to its suitability for high-speed compressible flows, a characteristic inherent to steam ejectors. This project includes a primary inlet entering methane with high pressure of 3,686,000 [pa] and a secondary inlet entering the air with pressure of 104,800 [pa]. This high-pressure differential is necessary to drive the entrainment of the air by the methane gas, a key aspect of the steam ejector operation.

The k-epsilon realizable turbulence model with standard wall functions is selected due to its accuracy in predicting the onset and amount of turbulence, especially in high-speed flow situations and for converging-diverging nozzle of the steam ejector.

Conclusion

The pressure, velocity, temperature contours are obtained to see performance and operational characteristics of the steam ejector. Simulation results revealed a maximum temperature of 313 K, indicating the intense heat transfer that occurs as the methane gas and air mix and expand within the ejector. This is a critical parameter, as it directly influences the efficiency and performance of the steam ejector.