ECOS is a sorptive cooled heat exchanger employed for building air-conditioning. The novel system is the implementation of an original desiccant and evaporative cooling process. The new concept aims to overcome the thermodynamic limits of conventional DEC systems, allowing a higher energy efficiency and performance. The design of the process results in a higher dehumidification potential in comparison with conventional systems. It is particularly intended as a desiccant cooling system for climates with high ambient air humidity (e. g., Mediterranean and tropical). Moreover the novel system avoids the complexity of the rotating parts necessary in standard systems and gives the possibility to apply the DEC concept even at small scale plants.

The process is based on simultaneous sorptive dehumidification and indirect evaporative cooling of the supply air stream. Moreover the indirect evaporative cooling is obtained through a continuous humidification process, ensuring a high heat exchange potential.

The system implementing the process is based on a counter-flow air-to-air heat exchanger technology. The heat exchanger is divided in sorptive (black line in Figure 3) and cooling (grey line) channels, which are physically separated but in thermal contact. The sorptive material is fixed on the heat exchanger sorptive channels. In the sorptive channels the supply air is dehumidified. In the cooling channels a continuous humidification of the cooling stream takes place. The latter, used for indirect evaporative cooling of the supply air stream, is for this purpose always kept in close-to — saturated conditions during the process.

The complete system consists of two sorptive heat exchangers, operated periodically. The periodic operation of two heat exchangers enables a quasi-continuous air-conditioning process. While one component is used in air-conditioning operation mode the other one is regenerated and pre-cooled before the next air-conditioning operation mode. In the regeneration the water vapour load of the sorbent material is released to the environment by means of a hot air stream (60-95°C). The air is heated through a heat exchanger connected to the solar plant. The subsequent pre-cooling phase is intended to lower the temperature of the heat exchanger after the regeneration, taking up the heat stored in the heat exchanger thermal mass. Moreover, a complete air-conditioning system will include at least a humidifier at the entrance of the cooling channel which brings the air at almost saturated conditions before entering the channel. Another optional humidifier can be installed on the supply air side in order to exploit the potential for direct evaporative cooling of the process.