| Traditional finned tube sensible heat exchanger is widely used in the fields of airconditioning, power plant and chemical engineering, etc. If the desiccant material is coated onthe aluminum foil surface of finned tube heat exchanger, which formed desiccant coated heatexchanger (DCHE). It can exchange sensible heat and latent heat simultaneously. It can beexpected that DCHE will have good heat exchange efficiency. Applied to the air conditioningsystem, DCHE can significantly improve air-conditioning’s the coefficient of performance(COP) and reduce energy consumption. In this paper, the ion exchange resin desiccant coatingon aluminum foil surface of finned tube heat exchanger is studied.Using ion exchange resin (IER) modified by hygroscopic salt LiCl or MgCl2as desiccant,and the powder coating as binder, the modified ion exchange resin(MIER) desiccant coatingon aluminum foil surface of finned tube heat exchanger was prepared by electrostatic spraying.The effects of impregnation conditions such as the salt concentration, the impregnationtemperature and time on the adsorptive performance of MIER were discussed. The influencesof the MIER mass fraction, curing temperature and time on the performance of desiccantcoating were also investigated. The composition and the surface morphology of the MIER andits coating were characterized using X-ray diffraction (XRD), scanning electron microscopyand energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy(XPS). Thermogravimetry (TG) and temperature programmed desorption (TPD) were used toevaluate the thermal stability and the desorption performance of the MIER desiccant coating.The XRD spectra showed that MIER structure had no obvious change after modification.SEM images revealed that the MIER desiccant coating could uniformly and closely disperseon the surface of aluminum foil and its thickness was about120μm. EDS and XPS analysisshowed the composition and the modified ion content of the desiccant coating. TG curvesindicated the weight loss of the MIER desiccant coating mainly happened in the range of30-150℃and400-600℃.The former was associated with MIER desorption, while the latterwas related to the thermal decomposition of MIER as well as power coating. TPD curvesindicated that the desorption activated energy of the modified desiccant coating was slightly increased. The static and dynamic adsorption curves of the modified desiccant coatingindicated that the adsorption performance had been improved significantly after modification.The hygroscopic repeatability test showed a excellent stability for adsorption and desorptionof the MIER desiccant coating. |
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