Modeling and simulation of ammonia jets under flash boiling conditions

This study examines the flash boiling of liquid ammonia in a step-counterbore nozzle using both equilibrium and non-equilibrium thermodynamic models. A comparative analysis is conducted between the Homogeneous Relaxation Model (HRM) and the Real Fluid Model (RFM) to evaluate their effectiveness in predicting key spray characteristics. The study investigates the influence of thermodynamic assumptions on spray behavior, focusing on key parameters such as vaporization rate, density, velocity, temperature distribution and spray cone angle. The impact of liquid metastability on flash boiling atomization is explored by comparing the non-equilibrium HRM modeling with the equilibrium RFM framework. It has been shown that flare flash boiling inside the nozzle can affect the spray behavior and its cone angle. The numerical predictions are assessed against experimental data to determine the strengths and limitations of each model in capturing flash boiling dynamics.