Solar cooling in Madrid: experimental results obtained to partial load during 2003 summer

This paper provides experimental results derived through field testing of a partial load solar energized cooling system in Madrid during the summer period of 2003. Solar hot water was delivered by means of a 50 m2 array of flat-plate collectors to drive a single-effect (LiBr/H2O) absorption chiller of 35 kW nominal cooling capacity. Thermal energy was stored in a 2 m3 stratified hot water storage tank during hours of bright sunshine. Chilled water produced at the evaporator was supplied to a fan coil units and the heat of condensation and absorption was rejected by means of a forced draft cooling tower. Instantaneous, daily and period energy flows and energy balance in the installation is presented. Peak insolation of 969Wm-2 (at 12:30 solar time on 08/08/03) produced 5.13kW of cooling at a solar to cooling conversion efficiency of 11%. Maximum cooling capacity was 7.5kW. Cooling was provided for 8.67 hours and the chiller required a threshold insolation of 711 Wm-2 for start-up and 373 Wm-2 for shut-down.