On the behaviour of hygroscopic wheels: Part II – rotor performance

The simplified model developed in Part I for the behaviour of a channel with parallel desiccant walls is adapted and used to analyse heat and mass transfer phenomena in hygroscopic rotors, the so-called enthalpy wheels and desiccant wheels, operating in steady-state conditions. The characterization of the corrugated matrix and an inspection of the effect of the corrugate curvature are presented. Global parameters characterizing the performance of the hygroscopic rotor are defined, and evaluated after the numerical results for the cyclic stationary behaviour of a real shape channel. Parametric studies are presented, concerning the steady-state performance of an equally partitioned desiccant wheel having sinusoidal-type channels. The influences of the dimensions of the matrix cells and of the constitution and thickness of the channel walls, as well as of the rotation speed and the inlet airflow conditions on the performance of desiccant wheels were analysed. The results presented provide a powerful insight into the operation of this type of devices, the model being an interesting tool both for manufacturing and design purposes.