An ammonia flash break-up model based on bubble dynamics with force and energy analysis on droplet. (15th June 2023)

• Record Type: Journal Article
• Authors: Shin, Jisoo; Park, Sungwook
• Is Part Of: Fuel. Volume 342(2023)
• Publication Date: 2023-06-15
• Subjects: Ammonia -- Flash boiling -- Break-up model -- Computational fluid dynamics -- Ammonia direct injection; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2023.127841
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: Rayleigh–Plesset equation with compressibility was employed to calculate bubble growth in liquid ammonia. Flash break-up regime was determined based on relationship between surface tension and pressure force at droplet surface. The change in velocity of spray by flash breakup was calculated based on the surplus energy and bubble growth rate. The developed model in this study had a good agreement with the previous experimental results of ammonia spray than only use the aerodynamic break-up model. Abstract: Ammonia flash break-up model was developed using bubble dynamics based on force analysis of surface tension and pressure forces in this study. The initial bubble radius was calculated by modifying bubble number density equation considering the superheat degree with assuming a single bubble in the droplet. The Rayleigh–Plesset equation with compressibility factor was employed to calculate bubble growth in the liquid ammonia droplet. Droplet disintegration was predicted by force analysis. The velocity change by flash break-up was assumed to be a product of the surplus energy between the surface-energy change and the pressure work, and the bubble growth rate. The simulation results were compared to results in a previous experimental study of ammonia spray behavior. The time constant of the thermodynamic breakup model was added to simulate the flash boiling condition that induces rapid spray changes. In this study, the time constant 12 is used through the verification process. Compared with previous experimental results of ammonia flash boiling spray, the proposed flash breakup model was superior in predicting radial spray development by the flash boiling compared to the conventional aerodynamic breakup model.