Investigation of a solar cooling installation in Tunisia

In this paper, we present a solar cooling installation located at the Center of Researches and Energy Technologies (CRTEn), in Bordj-Cédria, Tunisia. It is composed mainly of parabolic trough solar collectors, a 16 kW LiBr double effect absorption chiller associated with a cooling tower, a backup heater, two tanks for storage and drain-back storage and a set of fan-coils installed in the building to be conditioned. The system was run in the summers 2008 and 2009 using a water solution as heat transfer medium (HTF) without storage. In summer 2010, thermal oil was used as a HTF instead of water and two tanks were added, one for temperatures stabilities and the other one as a backup tank for night storage. Two running strategies of the installation were adopted; starting with or without backup heater. The site specifications, the building loads, the chillier temperatures and heat flows, the parabolic trough solar collector efficiencies, the installation powers and performances were analyzed. It was found that the coefficient of performance COP was ranged between 0.8 and 0.91 during the installation running while the solar coefficient of performance SCOP was between 0.1 and 0.43. The maximum output of the absorption chiller was around 12 kW. The drain backup night storage has improved the average solar fraction SF of the system which increased from 0.54 to 0.77. The avoided CO2 emission during a cooling season was estimated to be about 3000 kg corresponding to an equivalent energy saving of 1154 l of gasoil.