Numerical Modeling and Simulation of Injection Cooling and Wet Gas Compression

Abstract

This paper presents application of Computational Fluid Dynamics (CFD) in modeling wet gas compression in a multiphase compressor, where liquid is injected inside the compression chamber to enhance cooling and achieve near isothermal compression. CFD is used for detailed flow field and heat transfer analysis. It includes 3D transient simulations of multiphase compressible turbulent flow. During each cycle, compression and suction chambers keep moving and deforming. Computational domains include a gate that separates compression chamber from the suction chamber. Gate moves up and down to always remain in contact with the rotor. A custom program is used to prescribe motion for the moving and deforming domain. Eulerian-Lagrangian method is used to model continuous and discrete (atomized droplets) phases and their interaction. Droplet dynamics under the influence of turbulence, acceleration, diffusion and body forces are studied. Models to capture droplet breakup and coalescence are included. Results from CFD simulations are used to optimize compressor performance. Temperature and pressure variations during the compression cycle are presented. Most of the pressure and temperature rise occurs towards the end of the compression cycle. Atomization details including droplets trajectory, droplet size distribution and droplet velocity variations are presented. Temperature distribution inside the compression chamber is used to optimize location, size, and flow rate of liquid injections.