System and method for improving the performance of desiccant dehumidification equipment for low-humidity applications

Dehumidifier apparatus of the solid desiccant type having a desiccant wheel and wheel drive, a housing with internal baffles and air seals proximate to the wheel face to 5 create plenums or sectors and prevent air from leaking between adjacent sectors, to create three paths for air to pass through the wheel; the sectors being sequentially: (a) a reactivation sector provided to dry the desiccant to a low equilibrium humidity; (b) a process sector to 10 (i) dry return air from the process and makeup air received from the outside air sector, or (ii) receive all its inlet air from the outside air sector, or (iii) dry and independent air and/or gas stream which is recirculated from a space or process, ambient air, or 15 (iv) a mixture of the two; and (c) an outside air sector to (i) dehumidify another airstream to provide makeup air for the process sector and all the air for the reactivation sector; or (ii) to dehumidify another airsteam to provide pre-dehumidified air for 20 the process sector and all the supply air needed for the reactivation sector, or (iii) to dehumidify another airstream to provide all the air for the reactivation sector, respectively.