An innovative solar assisted desiccant-based evaporative cooling system for co-production of water and cooling in hot and humid climates

Abstract

Although evaporative coolers consume much lower electricity than the vapor compression systems, they are not applicable in humid climates. Combination of desiccant wheels and evaporative coolers, known as desiccant-based evaporative cooling systems, allows evaporative coolers to be used in humid climates, which provide significant energy and environmental advantages with respect to vapor compression systems. However, one of the main disadvantages of evaporative cooling is the high water. Regarding the global water crisis, a cooling system which saves both water and energy will be an attractive alternative to the current cooling systems. To this aim, this paper presents a novel desiccant-based evaporative cooling system for co-production of water and cooling. In this system, the moisture content of exhaust regeneration air is recycled to cover all of the evaporative cooler water consumption, and also part of the domestic water usage. To evaluate the system performance, dynamic hourly simulation of the proposed system as well as a reference vapor compression system was performed for a typical 60 m2 building in hot and humid climate of Bandar Abbas, Iran. The simulation results show that the proposed system is able to provide comfort temperature and relative humidity in a hot and humid climate. Moisture harvesting produce about 590 L water during a week, which covers all of the evaporative cooler water consumption, and provides an excess amount of 289 L for domestic usage. Monthly integrated results indicate that electricity consumption of the proposed system is 60% lower than the reference system, while its natural gas consumption is 30% higher than VCS, which is due to the high regeneration temperature in some hours. In other worlds, this system replace electricity consumption, a high-exergy and expensive energy carrier, with heat consumption. This system leads to 18.7% saving of CO2 emissions over a month. Economic evaluation proves the economic feasibility of proposed system with a payback period of 3 years. In conclusion, proposed system provide a more environmental friendly cooling system for water, energy and carbon saving.