A MOLECULAR DYNAMICS SIMULATION OF NANOSCALE WATER VAPOR ABSORPTION ON THE SURFACE OF LiBr AQUEOUS SOLUTION

A new architecture for absorption refrigeration systems (ARSs) that enables a significant enhancement of heat and mass transport processes has been proposed. This enhancement in performance is expected to translate into a significant reduction is size and cost of ARSs. The key innovation in the new approach is the use of ultrathin liquid films constrained by highly permeable nanostructured membranes. This approach enables far greater performance than those in the existing macroscale. For example, in the new absorber design, the thin film of LiBr solution is constrained by hydrophobic porous membranes and the inner wall of cooling water channel. The LiBr solution is held outside of the membrane by a meniscus formed over the membrane pores. The solution is cooled by water running in the cooling channel. This paper reports a detailed analysis based on molecular dynamics simulations to obtain a fundamental understanding on the nanoscale transport processes. The effects of LiBr concentration and the water vapor temperature elevation on the condensation coefficient and condensation mass fluxes have been evaluated. A model is also developed to predict the average condensation coefficient for a complete vapor energy spectrum. A comparison between the nanoscale and macroscale condensation mass fluxes is also provided.