Performance analysis of a solid desiccant enhanced indirect evaporative cooling system

This study proposes a disruptive cooling technology that thermodynamically hybridises two different cooling devices namely, a solid desiccant dehumidifier (SDD) and an indirect evaporative cooler (IEC) in order to enhance the performance IEC for all-weather conditions. Unlike conventional rotary desiccant wheels, the solid desiccant dehumidifier incorporates with desiccant coated heat exchangers to improve moisture removal capacity of desiccant by cooling the adsorption heat of desiccant. The indirect evaporative cooler operates based on M-cycle, which creates sensible cooling effect without the change of moisture level. In the proposed cooling system, the sensible and latent of the air are to be de-coupled. The latent cooling load, which is 25 to 45% of the total cooling load in most weather, is first removed by adsorption of vapour using desiccant coated heat exchangers. The saturated adsorbent is then regenerated by using either low-temperature waste heat from industry and/or renewable energy such as solar energy and geothermal energy. With the de-coupling of the latent cooling, the remaining sensible cooling load is removed by the indirect evaporative process where water is evaporated by the purged air from the dry channel, flowing over water-film surfaces in the wet channel. A numerical simulation has been carried out so as to compare the performance of the cooling system in terms of cooling capacity and dew-point effectiveness with a single IEC. The experimental data obtained from the previous research was employed as the inlet conditions for IEC. Key results revealed that the proposed SDDIECproduced higher cooling capacity, as well as higher dew-point effectiveness under the same operating conditions.