6533b82efe1ef96bd1294491

RESEARCH PRODUCT

Zeolite-gas systems and solar refrigeration : a study of the adsorptive properties at high pressures in the R22 freon-13X zeolite and ammonia-13X zeolite systems

subject

description

The adsorption of ammonia and R22 freon on 13X zeolite was studied in the conditions of possible use of these fluids in heat machines for solar refrigeration. The ranges of temperature and pressure, investigated in this study, extended from 0 to 80 °C and from 10-1 to 6 105 Pa respectively. The adsorption isotherms were collected by microgravimetry using a thermobalance specially built to be used in aggressive gases at pressures up to 106 Pa. Weak hysteresis was detected when ammonia was desorbed below 80 °C. A critical study concerning both applicability of classical adsorption equations (Dubinin-Radushkevitch and Langmuir) and comparison with other zeolite-gas systems is presented. Comparison with metallic salt - ammonia systems previously investigated is also briefly presented. Both types of chemical systems are thermodynamically and kinetically well-adapted to solar refrigeration in hot countries. Nevertheless it is clearly concluded that, as far as kinetic limitations due to swelling of solids can be improved, monovariant chemical systems should be preferred to divariant systems when high heat power and thermal energy are requested.