Numerical analysis of liquid desiccant dehumidification system with novel trapezoidal baffled surface

Abstract

Environmental concerns as well as a rapid decrease in fossil fuel reserves, raise the need for a substitute to the conventional vapor compression system (VCS). Low-grade energy run liquid desiccant absorption system is emerging to be a viable substitute to the VCS. One of the major barriers to the development of a liquid desiccant absorber (LDA) is its low effectiveness. Current study proposes a modification of the flat surface profile of a falling film type liquid desiccant absorber with a trapezoidal baffled profile. The numerical model involves a 2-D transient, multiphase-multicomponent system with conjugate heat-mass interaction. The complex governing equations are solved using ANSYS FLUENT 19.2. The computational model under consideration is validated using the experimental results. The maximum deviation is observed to be 10.31% and 0.38 K in terms of humidity and temperature, respectively. It is observed that the performance is maximized with an trapezoidal baffled configuration of p:e = 10:1.5. The incorporation of trapezoidal baffled surface (p:e = 10:1.5) augmented the dehumidification and enthalpy effectiveness of the system by 26.1% and 24.2%, respectively. The desiccant solution concentration of 35% and temperature of 293 K are optimum inlet conditions for better designing of the absorber. Also, it is observed that minimum the air velocity, maximum is the effectiveness. The proposed modification is found to have 12.1% improved dehumidification effectiveness compared to the earlier configuration of the triangular corrugated solution wall. The same is observed to yield lesser dehumidification effectiveness of 4.85% compared to sinusoidal geometry, proposed earlier.