Experimental evaluation of a low-power direct air-cooled double-effect LiBr–H2O absorption prototype

This paper describes a new small air-cooled double-effect LiBr–H2O absorption prototype directly powered by fuel and discusses the experimental findings for some tests carried out in Madrid in 2007, with natural gas as energy source. The prototype, which has been designed to supply 7 kW of cooling power, was able to chill water up to 7–18 °C under extreme outdoor temperatures. A new flat-sheet adiabatic absorber was used allowing it to operate at outdoor temperatures about 45 °C without any sign of crystallization. A mean daily coefficient of performance (COP) of about 1.05 was obtained. Since this absorption machine does not need cooling tower, there is neither water consumption nor Legionella pollution. Moreover, it is a quite compact unit. The ratio of cooling power over volume is about 6.0 kW/m3, while for the only air-cooled absorption chiller, Rotartica 045v, in the marked until 2009 this ratio is 4 kW/m3. When comparing with electric chillers presently on the market, this prototype was found to have a cooling cost approximately 15.9% higher and an environmental impact 16.7% lower. The absorption prototype is a more environmentally friendly solution as it does not emit fluorinated refrigerants.

► Results obtained for residential AC with an air-cooled double-effect direct-fired LiBr–H2O prototype, are shown for Madrid. ► The results shown are: working temperatures of generators, absorber, condenser, energy consumption and the cooling power. ► Finally an evaluation of the energy cost and the CO2 emissions are determined. ► These results are compared with the energy consumed, the cost and the CO2 emissions generated for the air-cooled electrical chiller.