Effect of operating temperatures on the coefficient of performance of active carbon-methanol systems

Abstract Experimental and predicted results of an active carbon (AC35)-methanol pair as a function of operating temperatures are discussed. Experimental COP 's higher than 0.5 are obtained when the evaporating temperature lift is less than 25°C. The COP is seen to be very sensitive to the evaporating and adsorbing temperatures. The regenerating temperature is of the order of 100°C which makes that pair a good candidate for solar cooling applications. A comparison between the results obtained with that pair and predicted performances of three other pairs (NH 3 H 2 O, ZeoliteH 2 O and another active carbon-methanol pair) shows that: 1. (1) two adsorber cycles give higher COP 's than the NH 3 H 2 H 2 O continuous cycle; 2. (2) intermittent adsorptive cycles give higher COP 's than the NH 3 H 2 O continuous cycle as long as the evaporating temperature lift is less than 50°C; 3. (3) among the solid adsorbents, the active carbon-methanol pairs seem to be the most promising for cooling applications. The choice of the active carbon depends on the evaporating temperature lift: AC35 is very well adapted for temperature lifts larger than 30°C; ACLH could be better adapted to smaller evaporating temperature lifts, as suggested by Passos et al .