HEAT AND MASS TRANSFER ANALYSIS OF AN S PATTERN SMALL CHANNEL ABSORBER IN AN AMMONIA WATER ABSORPTION SYSTEM

摘要

Absorber is the key component of an ammonia water absorption system. Falling film absorption is advantageous on efficient use of absorption heat due to its large temperature glide. Large bulk and weak heat and mass transfer performance are the main drawbacks. This paper proposed a novel S pattern small channel falling film absorber to increase specific area of absorption and enhance heat and mass transfer thus the absorber bulk could be reduced. A numerical study on the ammonia water vapor absorption process was presented. A differential mathematical model was developed for the novel absorber on the basis of mass and energy balances and heat and mass transfer equations. Double film theory in which simultaneous heat and mass transfer processes were considered both in the vapor and liquid phases was applied for the steady state simulation. Finite-difference method was applied to solve the model with dividing reasonable micro-units of the S tube. The temperature and mass fraction profiles along the absorber were obtained as well as the mass flux across the interface. And the characteristics of the absorption process were stated. The analysis provided an insightful comprehension of the novel absorber.