A comparison of collision kernels for sprays from one and two-nozzle atomisation systems

Abstract

A comparison has been carried out of the use of two combinations of collision kernels to predict the coalescence rates in water sprays from a single nozzle and two nozzles together, based on measurements of droplet size distributions. In the single-nozzle case, combinations of parameters were fitted to experimental data to give a standard error for the difference between actual and fitted volume percentages in the final spray of 1.4% for the first kernel, while fitting the kernel of Abrahamson [J. Abrahamson, Collision rates of small particles in a vigorously turbulent fluid, Chem. Eng. Sci. 30 (11) (1975) 1371–1379] by similarly adjusting parameters gave a standard error of 0.68%. Using these fitted values of parameters with data from two nozzles together gave a standard error of 3.3% with the first kernel, compared with 2.2% for the kernel of Abrahamson [J. Abrahamson, Collision rates of small particles in a vigorously turbulent fluid, Chem. Eng. Sci. 30 (11) (1975) 1371–1379]. The relevance of the work is that the kernel of Abrahamson [J. Abrahamson, Collision rates of small particles in a vigorously turbulent fluid, Chem. Eng. Sci. 30 (11) (1975) 1371–1379] may be useful for these simple simulations and for computational fluid dynamics (CFD) simulations of coalescence and agglomeration in spray dryers that are based on Eulerian–Eulerian approaches.