Alternative Refrigerants for Solar Absorption Air-Conditioning

Three hydrocarbons are considered as refrigerants for solar absorption air-conditioner. The cooling plant is composed essentially of the absorption chiller and the solar system is simulated with three working pairs: propane/octane, butane/octane and iso-butane/octane. Results are compared to those of ammonia/water mixture at the same fixed operating conditions and assumptions. The main advantages of the investigated refrigerants are their similar cooling effect compared to ammonia with a coefficient of performance reaching 0.63 and their relatively low working pressures. Nevertheless, the circulation ratio for hydrocarbon mixture is higher compared to ammonia. Propane/octane working mixture seems to be suitable for solar absorption air-conditioners with some particular precautions. The heat required to drive the absorption system is provided by evacuated tubes solar collectors of 90 m(2), a value in agreement with commercialized solar absorption air-conditioner operating with ammonia.