A solar air-conditioning pilot plant has been built and is currently running in PROMES laboratory (Perpignan France). This pilot, of a daily cooling capacity of 20 kWh, is based on a solid/gas thermochemical sorption process that is powered at 60-70°C by 20m2 of flat plate solar collectors. The thermochemical sorption process rests on the coupling of a reversible chemical reaction between a reactive solid (BaCl2) and a liquid/gas phase change of a refrigerant (NH3). Its functioning mode is intrinsically discontinuous and cyclic and is thus well adapted to the storage/transformation of solar energy. Indeed, the process comprises two main reactive phases that are carried out under different thermodynamic constraints: a diurnal regeneration phase followed by the useful production of cold during the night phase. During the first phase, the heat supplied to the reactor in the range of 50 to 70°C by the flat plate solar collectors enable the decomposition reaction of the reactive salt which releases the reactive gas that condenses in a condenser and accumulated at ambient temperature. When there is a surplus of solar energy, this one can be stored at 80°C by melting a phase change material (wax) for either enabling a faster heating of the reactor during the morning, or for domestic hot water production The cold production during the night consists in cooling the reactor which reabsorbs chemically the reactive gas that evaporates in the evaporator and thus producing the cold. The produced cold at -5°C to 0°C is stored in another PCM that solidifies below 4°C, in order to be delivered according to the cooling demand all along the day. An analysis of experimental results leads to an averaged efficiency of 50% for the solar collectors and a process COP ranging from 30 to 40%, leading thus to a daily cooling productivity for the thermochemical process of about 0.8 to 1.25 kWh of cold at 4°C per m2 of solar collector.

3. Results

3.1 Expected results

The investment cost of solar cooling systems is much higher than those of conventional air conditioning equipments. For instance, the cost of the sorption installations vary widely depending on the facilities, from 4000 €/kW up to 10 000€/kW, while the price for conventional compression air conditioning is around 300 €/kW. On the other hand, even if the technologies involved are common they are still poorly understood when set up in a building. Before considering a wide dissemination of these processes, it is necessary to fill a number of gaps concerning the estimation of energy, environmental and financial efficiency, the optimization of the thermodynamic processes and the lack of decision-making tools for pre studies and studies. To allow wider dissemination of solar cooling, the issues of research programs for the years to come are therefore

to reduce installation costs and to ensure optimum performance. The first expected result for ORASOL is to define what is the best cooling process according the building type and the climate. This answer will be brought by the analysis carried out by the pool 1. Then it is important to provide accurate but also validated simulation software for each solar cooling technology. These tools aim to support all research works on solar cooling and must also be used as a basis for more sophisticated ones as, for instance, sizing or optimization tools.