Contact adsorption drying characteristics of heat and mass transfer phenomena
    Contact adsorption drying mechanism is very complex, a dynamic phenomenon occurring in the system , namely the adsorbent - materials , materials - materials , adsorbents - are likely to occur between the adsorbent moisture / heat transfer .
    When the wet material with an adsorbent ( both capillary - porous body ) contact, the adsorbent surface of the liquid by capillary action of moisture absorption , so the contact area of ​​the mass transfer rate and a great relationship . With the amount of material surface moisture gradually reduced , in a moment of absorbent material surface potential is equal to the adsorbent surface water potential, the interface between the material moisture transfer will be terminated. However, in the adsorbent particles and materials developed within the concentration gradient inside the moisture from the material to the contact surface migration. When the contact time is long enough , the adsorbent and materials will reach equilibrium moisture content . At this time , need to be separated regenerated adsorbent may be dried ( or regenerated ) and then contacting the adsorbent with the material for further drying .
    Adsorbent in the adsorption process will emit heat of adsorption . Physical adsorption heat of adsorption is small , usually slightly larger than the adsorbate heat of vaporization ( 80 a 120U/mol); chemical adsorption heat released large , 1mol adsorbate chemical adsorption heat can reach millions of coke, chemical reaction heat sentence almost the same magnitude , it is difficult desorption . Therefore, we can consider using the heat of adsorption , evaporation of water for the material to provide heat.