A CFD approach to investigate the effect of the flow field on thermal and moisture transport enhancement of a small-scale MOF dehumidifier

Solid desiccant dehumidification can achieve efficient moisture control in air-conditioning systems. A small-scale dehumidifier can quickly regulate the moisture load of a specific space, such as drug storage, cultural relics preservation, etc. Although many mathematical models have been proposed to predict the performance of desiccant-coated air-conditioning systems, only a few of them can be applied to such a small-scale device.

And many existing models take advantage of the empirical correlations to calculate the heat and mass transfer coefficients, which are infeasible to new desiccants and new system design and its optimization. In this work, we used the CFD method to investigate thermal and moisture transport performance on a small-scale Metal-organic Framework (MOF) based heat sink (SDCHS).

The model built up the relationship among humid air, desiccant, and heat sink and then coupled the subdomains of the fluid flow, heat transfer, and specie transport. The reliability of this model was validated by the experimental tests of SDCHS under different operation conditions. Based on the measured results of humidity ratio and temperature, the discrepancies were maintained below 15%.

A parametric optimization was subsequently carried out on the flow field of SDCHS to enhance the heat and mass transfer, and various performance indexes were calculated to demonstrate the maximum utilization efficiency under the given operating condition. This dimensional analysis provides some simple guidelines to the design of SDCHS with the most suitable geometry