Second generation of freescoo Solar DEC prototypes for residential applications

Abstract

Freescoo is an innovative all-in-one compact solar Desiccant Evaporative Cooling (DEC) air conditioner concept. Results of the first prototype developed were presented at SHC Conference last year. Now a second generation of freescoo prototypes for applications in residential and small office buildings have been installed in Italy at ENEA Casaccia and at UNIPA. The thermodynamic cycle is based on the use of fixed and cooled adsorption beds and advanced evaporative cooling concepts. The adsorption bed, which is a fin and tube heat exchanger packed with silica gel grains, allows simultaneous dehumidification and cooling of the process air. The indirect evaporative cooling process, operated downstream to the dehumidification, is realized using an optimized configuration with two wet plate heat exchangers connected in series. Low wet bulb temperatures reached on the secondary flow, allow supply air temperatures to the room below 20°C. Systems are designed also for stand-alone operation thanks to a battery accumulator and PV cells installed. No auxiliary device is used for cold production. The main features of the second generation prototype system are first discussed, as well as some optimizations carried out from the first to the second generation prototype. Results are related both to field monitoring data. Performance indicators such EER and thermal COP, maximum cooling power achieved, stand alone operation data and control issues are presented and discussed.