Preparation and performance of desiccant coating with modified ion exchange resin on finned tube heat exchanger

In this paper, a desiccant coating with lithium and magnesium modified ion exchange resin (MIER) on finned tube heat exchanger was prepared by impregnation method and electrostatic spraying process, respectively. Impregnation condition and spraying process, which would badly affect the adsorption performance of MEIR desiccant coating, were investigated in detail. Also the morphology, structure, composition and thermal performance of desiccant coating were characterized by X-ray diffractometer (XRD), scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) and temperature programmed desorption (TPD), respectively. Besides, its cycle stability was also taken into consideration. The results manifested that electrostatic spraying technique and impregnation method can be employed to prepare a thick and uniform desiccant coating (120 µm) with modified ion exchange resin on finned tube heat exchanger successfully, which had an excellent cycle stability. The results of TPD analysis showed, for the enhanced interaction between the modified ions and water molecules, desorption activation energy of the modified resin can be raised slightly. And the static and dynamic adsorption curves of modified desiccant coating indicated that, whether in high or low humidity environment, the adsorption performance could be significantly improved after modification.