(398y) Low Dew Point Air Production Using Circulating Fluidized Bed

New desiccant air conditioning system, Mesh partitioned Counter current flow Moving Bed (MCMB), is proposed to replace conventional air conditioning system.  The system can use low temperature exhaust heat for regeneration of adsorbent, thus, it can save consumed energy for dehumidification in supercooling type dehumidifier in which 60 % of energy is expended.  Furthermore, the system can be achieved steady and isothermal operation, while it is unsteady and adiabatic operation in commercialized rotor type desiccant air conditioning system. MCMB is also applied to reduce a cost of production of a large amount of very low dew-point air, lower than -60 degree C, required in semiconductor manufacturing and lithium battery processes.  In this study, it is measured and analyzed phenomenon of dehumidification section in the MCMB to make clear its properties and enhancing dehumidification performance..
Dehumidifying section of experimental setup has 600 mm long with a rectangular cross-section of 50 mm by 10 mm for particle flow zone and 50 mm by 5 mm for air flow zone.  In some runs, 10 mm height is applied for the air flow zone.  Air is introduced from the bottom entrance and desiccant particles is introduced from the top entrance, then, counter current contact and steady operation are achieved.
It is observed exponential decrease of the humidity.  Because of the dehumidification rate constant increased with increasing φ , it is concluded that rate determining step stay at the mesh.  On the other hand, rate determining step is at particle boundary layer for cellulose and silica gel, because dehumidification rate constant is constant. When height of air flow zone is increased to 10 mm, dehumidification rate constant decreased to less than half and rate determining step is considered as the mass diffusion in gas phase.
MCMB can produce -52 degree C of dew-point air with 4 % of moisture content of desiccant particles.  Especially, 26 degree C of air and particle temperature is extremely higher than that of commercialized dehumidifier.  Dew point below -100degree C of dried air will be produced when the moisture content of desiccant is less than 1 %.
This paper makes clear that the rate determining step of three desiccant particles, effect of height in air flow zone on dehumidification rate constant.  Furthermore, possibility is demonstrated to produce the -100 degree C of ultra low dew point air.