EXPERIMENTAL-STUDY OF ADSORPTION EQUILIBR IUM OF WATER ON ZEOLITE ANDADSORPTION HEAT-STORAGE UNDER LOW RELATIVE VAPOR-PRESSURE

To apply the adsorption/desorption behavior of water on zeolite to a h eat storage system which can generate both warm and cold heat, equilib rium data under low relative vapor pressure were measured. Based on th e data the adsorptivities under adsorption/desorption are estimated. H eat storing/releasing characteristics were also studied by using an ex perimental heat storage device with 20 wt-% sodium chloride solution a nd zeolite 13 X. Heat storing/releasing cycles which have adsorptivity higher than 0.1 kg . kg(-1) per cycle even under relative vapor press ure as low as 0.1 and an evaporation process at temperatures lower tha n 0 degrees C, are achieved. A water-zeolite type heat storage system using a slight amount of sodium chloride for lowering the solidificati on point of water is proposed for heating and freezing applications.