Isothermal sorption characteristics of the BaCl2–NH3 pair in a vermiculite host matrix

Chemisorption could be useful in adsorption systems due to the large concentration change compared with physisorption. Equilibrium concentration characteristics of ammonia with a composite adsorbent material (BaCl2 impregnated into a vermiculite matrix) are investigated: the maximum concentration is about 0.4 kg ammonia/kg adsorbent. Hysteresis was observed between the synthesis and the decomposition reactions. The analysis of the data suggests that the hysteresis could be due to the dimensional changes of the solid during the reactions. The bi-variant behaviour observed was contrary to the mono-variant behaviour anticipated and the reasons are discussed. The COP of a basic adsorption cycle for typical ice-making and air-conditioning applications utilizing ammonia and the composite material were calculated. The results show that the material could be used for air-conditioning or other refrigeration applications. The COP could reach up to 0.6 at typical conditions (Tev = 15 °C, Tcon = 35 °C).