Increasing energy efficiency of displacement ventilation integrated with an evaporative-cooled ceiling for operation in hot humid climate

• Operation of displacement ventilation (DV) and evaporative cooled ceiling (ECC) system is modeled.
• The DV/ECC model was validated experimentally at different supply conditions and fixed load.
• Desiccant dehumidification was added to DV/ECC system for operation in humid climate.
• DV/ECC performance is optimized using genetic algorithm for minimum energy cost.
• DV/ECC operation at optimal conditions reduced cost by 28% compared to DV/chilled ceiling system.

The study investigates the optimized and enhanced performance of combined displacement ventilation (DV) and evaporative-cooled ceiling (ECC) using Maisotsenko cycle (M-cycle). The DV/ECC system efficiency is expected to improve by dehumidifying the supply air using solid desiccant (SD) dehumidification system regenerated by parabolic solar concentrator thermal source. Predictive mathematical models of the conditioned space, SD and DV/ECC are integrated to study the performance of the proposed system while utilizing an optimized control strategy for typical offices in moderate humid climate. The developed model was validated with experiments in a climatic chamber at certain supply conditions and fixed load. Good agreement was found between measured and predicted temperatures and loads removed, with a maximum percentage error less than 6%.A control strategy is adopted to determine optimal values of supply air flow rate and temperature and SD regeneration temperature while meeting space load, indoor air quality, and thermal comfort. The system performance is optimized to get minimal energy cost for a typical office case study in Beirut climate and compared to the cost of using chilled ceiling displacement ventilation (CC/DV) system. The use of the proposed system attained 28.1% savings in operational cost and electric power consumption over the cooling season.