Modeling and optimization of poultry house passive cooling strategies in semiarid climates

Abstract

Meeting hygrothermal and air quality requirements in livestock dwellings is crucial for upholding production quality standards. However, ventilation and air-conditioning in such enclosures is very energy-intensive, especially amidst climate change and intensifying summer conditions. This is due to large surface areas, livestock densities, and contaminants' generation rates. Hence, striving for more efficient passive cooling techniques is always a desired goal to reduce the anthropogenic emissions of the agricultural sector without compromising production quality. In this study, the energy savings' potential of two passive systems in a poultry house located in the semiarid climate of Beqaa Valley, Lebanon, was compared. The first system is the conventional stand-alone direct evaporative cooler (DEC), which evaporatively cools the outdoor clean air to temperatures close to its wet bulb. The second system combines with the DEC, an earth-to-air heat exchanger (EAHE) that sensibly precools the ambient air and reduces its wet-bulb temperature. This can increase the cooling capacity of the DEC, which can save substantial amounts of energy while achieving similar, if not better, indoor conditions. To conduct this study, simplified mathematical models were developed for the DEC, EAHE, and the poultry house space, assuming a well-mixed air volume. After sizing the systems, simulation results showed that the stand-alone DEC system was not able to meet relative humidity requirements at all times unlike the proposed hybrid EAHE/DEC system. Moreover, the hybrid EAHE/DEC system resulted in 40% reduction in air and water consumption rates compared with the DEC system during the summer season.