Numerical Model for Spray-Wall Impaction and Heat Transfer at Atmospheric Conditions

摘要

A numerical model is developed to simulate for atmospheric applications the impingement of water sprays on surfaces heated at temperatures ranging from nucleate to film boiling. The droplets are modeled in the Lagrangian frame of reference and are dispersed stochastically in the continuous gas phase, The model is based on the fundamental basics of single water droplet impingements extended to full sprays, where the overall heat-transfer process is broken down into its basic components: boiling heat transfer associated with the droplet contact, bulk air convection, and radiation. Droplet dynamics at the wall is modeled based on an empirical correlation relating the droplet incoming to outgoing Weber number. Droplet contact heat transfer is modeled using an effectiveness parameter for the heat transfer that is a function of the droplet Weber number. Numerically modeling the droplet-wall dynamics and contact heat transfer has not been addressed before in a numerical model. The model is tested at atmospheric pressure using experimental data for nozzles that disperse a spectrum of nonuniform droplets. Favorable comparison with the experimental data is demonstrated.