Thermodynamic analysis of adsorption cooling system using composite halide salts

In the development of an adsorption cooling system, it has been observed that halide composites exhibit less hysteresis than pure halide salts. Therefore, it is important to thermodynamically analyze the composite salt-based adsorption cooling system (ACS) to understand its performance. In this study, we conduct a thermodynamic first-law and second-law analysis of ACS using reactive salts such as BaCl₂, BaCl₂-ENG, CaCl₂-ENG, SrCl₂-ENG, and MnCl₂-ENG, with ammonia as the refrigerant. We compared the coefficient of performance (COP) with that of a pure halide salt-based ACS. The theoretical COP of the ACS at a mass ratio of 4 is estimated as 0.45, 0.4, 0.27, 0.37, and 0.22, and the second-law efficiency is estimated as 44.28%, 38.76%, 20.71%, 16.26%, and 6.92% for BaCl₂, BaCl₂-ENG, CaCl₂-ENG, SrCl₂-ENG, and MnCl₂-ENG reactive salts, respectively. Among the different salts, BaCl₂ shows the highest COP. However, the COP values are lower than the maximum theoretical coefficient of performance (COP_max) due to the sensible mass of the reactor, and COP values decrease with an increase in the mass ratio due to an increase in sensible mass. It is noteworthy that the COP of the pure salt-based ACS is higher than that of the composite salt-based ACS because the ammonia uptake of pure salt is greater than that of the composite salt.