Thermodynamic basis for the choice of working fluids for solar absorption cooling systems

Through the application of the first and second laws of thermodynamics upper and lower limits for the coefficient of performance (COP) of absorption cooling cycles are derived. These upper and lower limits, besides being dependent on the environmental temperatures of components of the cycle, are also dependent on the thermodynamic properties of refrigerants, absorbents, and their mixtures. With the use of these upper and lower limits of COP it is now possible to make a quantitative comparative study of different refrigerant-absorbent combinations. The technique developed is applied for the comparative evaluation of NH₃ + H₂O, NH₃ + NaSCN and H₂O + LiBr combinations which are the favorable candidates used in solar absorption cooling cycles.