ABSORPTION CHARACTERISTICS OF THIN LITHIUM BROMIDE (LIBR) SOLUTION FILM CONSTRAINED BY A POROUS HYDROPHOBIC MEMBRANE

An experimental study on absorption characteristics of water vapor into a thin lithium-bromide (LiBr) solution flow is presented. The Li Br solution flow is constrained between a superhydrophobic vapor-permeable wall and a solid surface that removes the heat of absorption. As opposed to conventional falling film absorbers, in this configuration, the solution film thickness and velocity can be controlled independently to enhance the absorption rate. The effects of water vapor pressure and cooling surface temperature on the absorption rate are studied. An absorption rate of approximately 0.005 kg/m(2)s was measured at a Li Br solution channel thickness and flow velocity of 160 gm and 4 mm/s, respectively. The absorption rate increased linearly with the water vapor driving potential at the tested solution channel thickness. The high absorption rate and the inherently compact form of the proposed absorber promise compact small-scale waste heat or solar-thermal driven cooling systems.