Improvement of cooling performance of water adsorption chiller by using aluminophophate adsorbent

We synthesized an aluminophosphate (AlPO4)-based adsorbent that shows great cooling performance when used in a water adsorption chiller as an adsorbent. This adsorbent is crystalline microporous (CHA-type structure) material, which is composed of aluminum, phosphine, and oxygen atoms. It shows high water adsorption capacity (0.3 g(H2O) g(ads)(-1)) at 308 K under 12 Torr of water vapor pressure (typical adsorption conditions of the adsorption chiller), and almost zero adsorption capacity at 348 K under 42 Torr (typical desorption conditions). This adsorbent shows much larger working capacity between the adsorption and desorption steps than silico-aluminophosphate (SAPO(4)) adsorbent which has same physico-chemical properties as the AlPO4, except for the absence of silicon species in framework. The commercial water adsorbent, FAM-Z02 is known to have the same structure as this SAPO(4). We confirmed that AlPO4 can be easily synthesized in a large scale with a high hydrothermal stability, and easily pelletized to 0.6-1 mm sphere-shaped particles. The present AlPO4 adsorbent was tested in lab-made water adsorption chiller with 5 kW scale, and it shows 523 W kg(-1) of specific cooling power (SCP). This experimental value was in good agreement with SCP (513 W kg(-1)) derived from simulation. The SCP of the AlPO4 adsorbent is 28% larger than that of the SAPO(4) adsorbent calculated from simulation.