Honeycomb rotor dehumidifiers have been used widely because of large surface area and rapid thermal response. Mass and temperature transfer behavior for the performance evaluation is rather complicated and a system of simultaneous partial differential equations of 8 variables must be solved under a cyclic initial condition for the complete simulation.

With high efficiency dehumidifiers, however, a relative heat capacity Λ(=ρ_cc_c(1-ε)Z/ρ_gc_gUt_c) is smaller than unity and a relative adsorption capacity M(=ρ_cq₀^*(1-ε)Z/C₀Ut_c) is higher than unity. When the cycle time t_c is selected properly under the above condition, each step of adsorption/desorption can be divided into two different time zones, i.e. a transition stage appearing just after switching the step until t/t_c<Λ and a subsequent thermal equilibrium stage. Sensible heat transfer is predominant in the transition region and reaches the thermal equilibrium within this stage. Thus, the mathematical solution becomes free from the cyclic condition to save the iteration. In the thermal equilibrium region, heat liberated by adsorption/desorption is balanced to warm/cool the streaming air, and the enthalpy of air is constant everywhere and equal to that of the feed/regeneration air. Since the amount adsorbed changes linearly, the time average values of temperature, humidity etc. can be calculated by a simple integration of the reciprocal of driving force, based on the short cycle time approximation or the continuous countercurrent flow model.

The above simplified model is proposed together with a graphical solution method and the result is compared with the more rigorous simulation.