Experimental study on heat and mass transfer performance of falling film absorption over a vertical tube using LiCl solution

Abstract

To discover the falling film absorption performance over a vertical tube using LiCl solution in a high-pressure absorber involved in a two-stage absorption refrigeration system, an experimental study on heat and mass transfer performance of the absorption process was conducted. Effects of operating parameters such as solution mass flow rate, absorber pressure, concentration and cooling water temperature on absorber performance are analyzed. Besides, a coupled heat and mass transfer model is applied and solved with a finite difference method in order to determine the heat and mass transfer coefficients. Mass absorption rates of absorption processes respectively using LiBr solution and LiCl solution are compared under the conditions of the same temperature and saturated vapor pressure of the solution. Results show that the mass absorption rate using LiCl solution is up to 19.7% higher than LiBr solution. In addition, dimensionless formulations of heat and mass transfer coefficients are correlated with the average absolute error below 15%. The study is also helpful to design and optimize such kind of absorbers using LiCl solution as working fluid.