Numerical modelling and parametric study of an air-cooled desiccant coated cross-flow heat exchanger

Air-cooled desiccant coated cross-flow heat exchanger (DCCFHE) system provides a simple and effective approach to improve dehumidification performance by using cooling air to remove adsorption heat during adsorption process. In this study, a novel numerical model validated by experimental data was established to predict the performance of a conventional silica gel DCCFHE system. The fin efficiency, as a variable due to the release of adsorption heat, was taken into account in the model. Parametric study for various air velocity and structural parameters was conducted to reveal their effects on the dehumidification performance. Results show that the smaller process air velocity is conducive to improve dehumidification performance, but the performance increases with the increase in cooling air velocity. Compared to the operation case without cooling air, the moisture removal capacity and dehumidification coefficient of performance can obtain about 35% improvement at the cooling air velocity of 1 m/s. The results also indicate that thicker desiccant layer thickness and smaller fin pitch improve moisture removal capacity and dehumidification coefficient of performance but result in greater total pressure drop Delta P, while the performance is insensible to fin thickness and fin height. Besides, effect of heat transfer performance in dehumidification and cooling sides on dehumidification performance was also analyzed. It was found that the heat transfer performance in dehumidification side is the dominant factor affecting dehumidification performance.