Performance evaluation of MIL-101(Cr) based desiccant-coated heat exchangers for efficient dehumidification

Abstract

Metal-organic frameworks (MOFs) with ultrahigh water uptake and moderate regeneration temperature are ideal sorbents for desiccant-coated heat exchangers (DCHEs). Herein, MIL-101(Cr) is synthesized through the hydrothermal method and the product shows an exceptional adsorption capacity of 1.17 g/g at 90 % RH and steep water uptake at middle RH (P/P0 = 0.35–0.45). Then MIL-101(Cr) coated heat exchangers (MCHE) are fabricated by the spraying method and a testing platform is established to investigate the dehumidification performance. Parameter analysis revealed that a medium switchover period (9–12 min), low-temperature heat sources (48–60 °C), and lower cooling water temperature facilitate the overall performance. Experiments under two different heat exchanger layouts are conducted, showing MCHEs in the parallel mode present better heat/mass transfer performance and MCHEs in the series mode tend to acquire higher heat recovery efficiency (η). Hot and humid climates are favorable in both modes while low-RH climates require lower inner cooling fluid temperature. Under five typical inlet air conditions, the dehumidification capacity of the parallel mode and the series mode ranges from 0.26 to 0.43 kg/h and 0.24–0.40 kg/h, and the η ranges from 0.30 to 0.47, 0.32–0.53, respectively.