Numerical investigation on heat and mass transfer characteristics of inclined plate falling film absorption with nano-lithium bromide solution

Nanofluids play an essential role in enhancing heat and mass transfer in falling film absorption processes. To reveal the underlying mechanisms of enhanced absorption by nanoparticles at the gas–liquid interface, an innovative model considering the Marangoni effect is proposed for falling film absorption on an inclined plate. The effects of copper oxide nanoparticles on heat and mass transfer for the inclined plate falling film absorption, utilizing lithium bromide solution as the working fluid, are numerically studied using the software COMSOL Multiphysics. The accuracy of the numerical model is verified by experimental and simulation results, showing superior agreement when the Marangoni effect is incorporated. The vapor absorption performance of lithium bromide solution is significantly enhanced by the addition of nanoparticles. Surface tension amplifies temperature and concentration gradients, playing a pivotal role in augmenting heat and mass transfer through the Marangoni effect. The largest temperature and concentration gradients occur at the gas–liquid interface. The interfacial heat transfer coefficient and mass transfer coefficient decrease along the length of the inclined plate and gradually stabilize at 15.01 W·m⁻²·K⁻¹ and 1.12 × 10⁻⁴ m·s⁻¹, respectively.