Hydrodynamics and heat transfer investigation of air–water dispersed flow

Details of two experimental sets for droplet deposition in vertical upward air–water dispersed flow are presented: stainless steel and Plexiglas test section – together with typical experimental results, using different liquid concentrations and mean droplet sizes. The results obtained for different gas Reynolds numbers, ranging from 4×10 4 to 9.5×10 4, are given. The measurements of deposition showed that commonly used assumptions about the effect of droplet concentration on increase in droplet size, and decrease in droplet turbulence cannot completely explain the observed decrease of the deposition coefficient with increasing droplet concentration. Better agreement was obtained by taking into account the effect of the droplet coalescence ratio to the wall (ratio between flow rate of coalesced droplets and droplets impacted on the wall). It is suggested that the presence of the liquid film cause a decrease in droplet coalescence ratio. An experiment is described on two-phase dispersed heat transfer. Wall temperature distributions are presented for a uniformly heated stainless steel test section.