| Most of the models to predict the heat and mass transfer in vertical absorption chillers underestimate the heat and mass transfer coefficients. Generally the models put too many constraints such as: laminar profile, constant properties, non-absorbable gases are ignored. This investigation attempts to create a more realistic model to estimate the air-cooled absorption process. The model couples the energy and mass balance equations through constraint equations at the interface. Using a method for computing the thermodynamic properties from a Gibbs free energy equation and correlations to estimate the transport properties, a robust MathCad routine was created that computes the solution composition and temperature as functions of the vertical position in the tube. The results from the model show that increasing the air content from 1 to 20% by volume reduces the mass absorption flux by 43%. Furthermore, it suggests that there is a critical tube length that depends on the air concentration at which the absorption process ceases (1.3-m for 1% air). |
