Rheology and convective heat transfer of colloidal gas aphrons in horizontal mini-channels

Colloidal gas aphrons (CGA) consists of closely packed minute gas bubbles with diameter ranging from 10 to 100 μm. It is produced by stirring a surfactant solution at high speed in a fully baffled beaker. CGA can be used in various applications such as bioremediation, bioreactors, oil recovery, and fire fighting. This paper reports experimental data for (1) adiabatic flow and (2) laminar convective heat transfer of CGA in five 1.58 × 0.76 mm2 mini-rectangular channels. First, it is shown that CGA is a shear thinning fluid. Correlation for the friction factor as a function of Reynolds number is compared with that of water and macrofoams. Then, the local temperature and heat transfer coefficient along the mini-channels are reported as a function of the mass flow rates and imposed heat flux. The heat transfer coefficients for CGA appears to be constant and independent of mass flow rate and imposed heat flux as well known for single phase laminar flow.