Numerical investigation of transient heat and mass transfer in a parallel-flow liquid-desiccant absorber

Abstract

Liquid desiccant systems have received significant attention as a way to reduce latent loads. Tests of liquid desiccant systems in humid climates have shown significant reductions in energy consumption. As moisture in the air is absorbed at the dehumidifier, the temperature of the liquid desiccant increases due to the addition of heat from the enthalpy of condensation of the water vapor. Thus, the coupled effects of heat and mass transfer are relevant for these applications. A two-dimensional mathematical model of the transient heat and mass transfer for an absorber where a thin film of liquid desiccant flows down its walls and dehumidifies the air in parallel-flow configuration is developed and the dynamics of the modeled system are analyzed. List of symbols

Simplified Heat and Mass Transfer Model for Cross-Flow and Countercurrent Flow Packed Bed Tower Dehumidifiers with a Liquid Desiccant System

“…The governing equations of heat and mass transfer for the lumped-capacitance model are as follows [21,38,[40][41][42][43][44]:…”

“…Using the non-dimensional parameters The dimensionless representation of the governing equations is as follows [42,43]: …”

Study on an internally-cooled liquid desiccant dehumidifier with CFD model

“…When it comes to internally-cooled dehumidifier, there are also three types of models developed on the basis of finite difference model [20]. They are models without considering liquid film thickness [26], models considering uniform liquid film thickness [27], and models considering variable liquid film thickness [28]. In the first model, the effect of velocity field on heat and mass transfer is ignored even though velocity, mass and energy are coupled.…”

Dynamic analysis of an energy efficiency dehumidifier for building applications

“…So far, the modelling techniques have been focused on steady state models of heat and mass transfer. [7][8][9] Gandhidasan [10] proposed a simplified finite difference model for LDDS, by which the water mass transfer rate between air and liquid was predicted. The simplified model was proved to be effective through experimental verification.…”