Operating with a set of velocities located at the left of the
limit will ensure that there is no gas loss in the process, and hence
a better process yield. Increasing the gas velocity beyond the frontier
results in a gas waste, then the foam void fraction cannot be
controlled. The limits obtained for SMX10 and SMX+6 seem to be
consistent with the previous hydrodynamic study: for a higher gas
flow-rate in the case of a smaller hydraulic diameter in the
SMX+6. Thus, reducing the SMX diameters does not induce radical
changes in the flow map frame, so that no particular issues are
brought to light in the scale-down. It can also be observed that
the limit shifts toward lower gas velocity with increasing liquid
phase viscosity. Most experiments have been made in triplicate
in the case of SMX10 and are at least doubled in the case of
SMX+6 (ranges of deviation are shown for each flow condition in
Fig. 6). Repeat experiments show a 5% standard deviation for the