Transient Thermal Phenomena during Spontaneous Water Migration in Zeolite Beds

The changes in local temperature occurring during spontaneous imbibition of columnar samples of dry natural zeolite with water were studied. The temperature pulses of 20-250 s duration and 3-40°C amplitude were registered and correlated with the wetting front motion observed with neutron radiography. The amplitude of the pulses was shown to increase with increasing ambient temperature. The broadening of the temperature pulse with increasing distance from the water supplied end of the samples was observed. The amplitude and the pulse width were found to depend substantially on the drying temperature of the material. The observed effect was attributed to the heat of immersion released in the sample at the moving wetting front.