Experimental evaluation of a direct air-cooled lithium bromide-water absorption prototype for solar air conditioning

A new direct air-cooled single-effect LiBr-H2O absorption prototype is described and proposed for use in solar cooling. As distinguishing aspects, it presents: an adiabatic absorber using flat-fan sheets: an air-cooling system that directly refrigerates both the condenser and the absorber and; the possibility of being operated also as a double-effect unit. A solar facility comprising a 48 m(2) field of flat-plate collectors was used to test the single-effect operation mode of the prototype. Results from an experimental campaign carried out in Madrid during summer 2010 are shown and operation parameters corresponding to two typical summer days are detailed. The prototype worked efficiently, with COP values around 0.6. Cooling power varied from 2 kW to 3.8 kW, which represented about 85% of the prototype's nominal capacity. Chilled water temperatures mostly ranged between 14 degrees C and 16 degrees C, although the lowest measured value was of 12.8 degrees C. Condensation and absorption temperatures were under 50 degrees C and 46 degrees C, respectively, even with outdoor temperatures of 40 degrees C. Driving water temperature ranged between 85 degrees C and 110 degrees C. As a mean, the system was able to meet 65% of the cooling demand corresponding to a room of 40 m(2). No signs of crystallization were observed during about a hundred hours of operation. (C) 2011 Elsevier Ltd. All rights reserved.