International Conference “Passive and Low Energy Cooling 663 for the Built Environment”, May 2005, Santorini, Greece Optimization and study of an autonomous solar desiccant cooling system C. Maalouf, E. Wurtz, L. Mora and F. Allard LEPTAB, University of La Rochelle, Av. M. Crepeau, 17042, La Rochelle, France ABSTRACT A desiccant cooling unit powered by 14.8 m 2 of solar liquid collectors is implemented in a train- ing room in Chambery in Eastern France. The system uses a Lithium Chloride sorption wheel and is optimized to work without an auxiliary heat regeneration source. Several parameters are studied in order to decrease primary energy con- sumption and increase system performance. The models are implemented in an object-oriented simulation environment called SPARK which allows system coupling with building models. Simulations show that airflow rate during inoc- cupation period is a key component in the op- eration of the system for it can help decreasing required regeneration hours. Our results suggest that an airflow rate of 2.8 ACH during inoccu- pation decreases the required regeneration hours of about 40% with an increasing of equipment electrical consumption of 8%. 1. INTRODUCTION Desiccant evaporative cooling is an alternative technology to traditional air conditioning sys- tems. Being heat driven, it can be coupled to solar collectors to produce a cooling system with low environmental impact. This technol- ogy has been widely used in USA and Northern Europe. In USA, the number of desiccant indus- trials has increased from 2 in 1980 to more than 10 in 2001 with more than 5700 systems in- stalled in the tertiary buildings (Stabat, 2003). Several studies in Northern Europe (Dittmar, 1997; Lindholm, 2000), demonstrated that solar energy used with desiccant systems, can reduce annual gas consumption by as much as 70%. Recently, these systems are used in Western Europe and especially in Germany where there are about 7 solar desiccant installations. In the commerce room of Fribourg in Germany, an autonomous solar desiccant cooling system al- lows cooling two meeting rooms of 65 and 148 m 2 containing 120 persons (Climasol, 2005). With 100m 2 of solar collectors and 60 kW of cooling capacity, reductions in primary energy consumption are about 30000 kWh and in CO 2 emissions about 8800 kg/year. Actually in France, a solar desiccant system is installed in Chambery (in Eastern France) to meet the cool- ing demand for a training room of 70 m 2 . This system will be studied in this paper. First, system operation and its control strat- egy are described and then component models are presented briefly. These models are imple- mented in an equation-based simulation envi- ronment called SPARK (Sowell and Haves, 2001). The main advantage of SPARK is its modularity which allows the creation of very flexible tools and allows user to build complex simulations. Using simulations, several parame- ters are investigated such as the effect of storage volume, collector slope and air flow rate during inoccupation period on system performance and equipment electrical consumption. 2. SYSTEM OPERATION Figure 1 shows the desiccant cooling air- handling unit coupled with the solar installation. This unit comprises a desiccant wheel in tandem with a thermal wheel with evaporative coolers in both air supply and return air streams before the thermal wheel. This system allows cooling and dehumidifying air without using conven- tional refrigerants. The desiccant wheel contains