A novel strategy for comprehensive optimization of structural and operational parameters in a supersonic separator using computational fluid dynamics modeling

Abstract

In this study, the effects of several structural and operational parameters affecting the separation efficiency of supersonic separators were investigated by numerical methods. Different turbulence models were used and their accuracies were evaluated. Based on the error analysis, the V2-f turbulence model was more accurate for describing the high swirling turbulent flow than other investigated turbulence models. Therefore, the V2-f turbulence model and particle tracing model were selected to optimize the structure of the convergence part, the diffuser, the drainage port, and the swirler. The cooling performance of three line-type in the convergent section were calculated. The simulation results demonstrated that the convergent section designed by the Witoszynski curve had higher cooling depth compared to the Bi-cubic and Quintic curves. Furthermore, the expansion angle of 2° resulted in the highest stability of fluid flow and therefore was selected in the design of the diffuser. The effect of incorporating the swirler and its structure on the separation performance of supersonic separator was also studied. Three different swirler types, including axial, wall-mounted, and helical, were investigated. It was observed that installing the swirler significantly improved the separation efficiency of the supersonic separator. In addition, the simulation results demonstrated that the separation efficiency was higher for the axial swirler compared to the wall-mounted and helical swirlers. Therefore, for the improved nozzle, the swirling flow was generated by the axial swirler. The optimized axial swirler was constructed from 12 arced vanes each of which had a swirl angle of 40°. For the optimized structure, the effects of operating parameters such as inlet temperature, pressure recovery ratio, density, and droplet size was also investigated. It was concluded that increasing the droplet size and density significantly improved the separation efficiency of the supersonic separator. For hydrocarbon droplets, the separation efficiency improved from 4.6 to 76.7% upon increasing the droplet size from 0.1 to 2 µm.

Measurement of the mass-flow-rate characterization parameters of high-pressure pneumatic servo slide valves

“…For the assumption that the flow velocity at the downstream valve orifice is the speed of sound in the mass-flow-rate characterization parameters measurement method of HPSVs, the CFD method was used to study the gas flow through the two valve orifices 26 . CFD is known as a robust method for predicting fluid dynamics parameters and the most common software is ANSYS/fluent 27 , 28 . As shown in Fig.…”

Investigation of novel passive methods of generation of swirl flow in supersonic separators by the computational fluid dynamics modeling

“…Three main refrigeration processes include Joule–Thomson (JT) process, turbo-expander process and 3S process 3 . The JT process is the most common liquefaction process in the natural gas industry, however, based on the results the separation efficiency of 3S is higher than JT process 3 , 7 . Alfyorov et al 17 reported this converging–diverging nozzle separates the natural gas species with up to about 20% saving in compressor energy consumption compared to the same operational condition conducted by the JT valve and Turbo-expander.…”

“…In recent years, a significant part of the studies have been done to optimize the thermal efficiency of various processes 3 , 7 – 9 . Process simulations and numerical studies are generally used for these optimizations 4 , 10 – 12 .…”

“…Process simulations and numerical studies are generally used for these optimizations 4 , 10 – 12 . The thermal efficiency can be improved in two ways: 1—modification of the mechanical structure of the investigated equipment 7 and 2—improvement of the thermo-physical properties of the base fluid 13 – 15 . For example, Ulah et al 14 employed the hybrid nano-liquid including a combination of AA7072 and AA7075 nanoparticles and water (water-aluminum alloy nanoparticles) to improve the heat transfer of investigated fluid.…”

“…Previously three different methods were proposed for generation of swirl flow inside the nozzle. One method is implementing the U type supersonic separator 19 , 20 , the second is using the delta wing which is mounted after the nozzle outlet 21 and the other is utilizing the static vane for generation of swirl flow 7 .…”