LiBr/H2O falling-film absorption is a common heat-and mass-transfer process in an absorption air-conditioning system. By analyzing the coupled heat and mass transfer of the falling-film absorption process

two-dimensional physical and mathematical models of the falling-film absorption along a vertical wall were established. The model was solved using the Fluent computational-fluid-dynamics software. The interfacial temperature

the concentration profile across the falling film

and the average heat-and mass-transfer fluxes and coefficients were obtained. The effect of the Reynolds number on the heat and mass transfer of the falling film was investigated. The results show that

when the film Reynolds number is less than 150

the average interfacial temperature increases with the increasing Reynolds number; however

the rising trend of the average interfacial temperature is more and more gentle. The average mass-transfer coefficient increases with the increasing Reynolds number

while the average heat-transfer coefficient decreases. Simultaneously

with the increasing Reynolds number

the average heat-and mass-transfer fluxes first increase and then decrease. An optimal Reynolds number exists that leads to the maximum heat- and mass-transfer fluxes. The average heat-and mass-transfer fluxes reach their maximums

7.2 kW/m2 and 2.9×10-3 kg/(m2?s)

respectively

when the Reynolds number is 50.