Abstract
The regeneration of water-loaded zeolite in superheated steam followed by the adsorption of water vapor in dry air was studied experimentally for designing an apparatus to produce water from dry air in desert areas. The following conclusions were reached :
1) A simulation of the adiabatic adsorption process after steam regeneration predicted well the experimental results; the temperature of the zeolite bed approached a plateau temperature, independent of residual water content and regeneration temperature, which can be estimated by Pan's equation.
2) The equilibrium water content measured in an atmosphere of superheated steam at temperatures above 573 K agreed well with the values calculated by Polanyi's equation, but became smaller than the calculated values at lower temperatures.
3) The heat transfer coefficient between the superheated steam and the zeolite was estimated from the experimental desorption rate to be about 2.3 W/m2·K at a mass velocity of 150 kg/m2·h, which agreed with the value calculated by Hyodo's empirical equation.
4) After 1, 000 times of regeneration with superheated steam at 623 K, the equilibrium adsorption capacity of the zeolite was decreased by about 15 % compared to that of virgin zeolite, and no significant change was observed in the X-ray diffraction pattern of the used zeolite.
