The solar-assisted absorption cooling system simulated in this work is represented in the schematic diagram of Fig. 1. The TRNSYS environment has been employed to set up the simulation [6]. TRNSYS has a standard library of components that includes most of the elements usually employed in HVAC installations.

The absorption chiller has been simulated with the model presented in [7], which is able to reproduce the typical behaviour of a commercial single stage LiBr-H2O chiller. The solar collectors considered are of the flat plate type, with special anti-reflective glazing. Their second order efficiency curve is obtained from the standard certification performed by the Solartechnik Prufung Forschung Institut.

To simulate the air-cooled heat exchanger performance a set of equations is written and solved by means of the engineering equation solver (EES), developed at the University of Wisconsin, Madison. TRNSYS is then linked to this external programme and all the variables of interest are dynamically exchanged between the two. The behaviour of the cooling towers is simulated thanks to a standard component of TRNSYS which relies on performance data supplied by the user.