Water supply rates for recirculating evaporative cooling systems in poultry housing

Authors: Purswell, Joseph - Jody; LINHOSS, JOHN - Mississippi State University; EDGE, CARSON - Auburn University; DAVIS, JEREMIAH - Auburn University; CAMPBELL, JESSE - Auburn University

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2018
Publication Date: 5/30/2018
Citation: Purswell, J.L., Linhoss, J.E., Edge, C., Davis, J.D., Campbell, J. 2018. Water supply rates for recirculating evaporative cooling systems in poultry housing. Applied Engineering in Agriculture. 34(3):581-590.

Interpretive Summary: Poultry growers use evaporative cooling systems to reduce incoming ventilation air temperature to mitigate heat stress and improve production efficiency. Newly constructed poultry houses use increased ventilation rates to further improve cooling and have resulted in increased water usage. Recent droughts and increasing municipal water costs have highlighted the need for proper planning and design of water supply systems to ensure peak demand is met. Few estimates of water use are available for recirculating evaporative cooling pad and fan systems, and design guidance has emphasized planning for extreme temperatures, resulting in excessive capacity recommendations. Historical weather data from 732 weather stations across the continental U.S. was used to estimate evaporation rate for differing levels of system efficiency. Frequency analysis was used to determine frequency of occurrence at 2%, 1%, and 0.4% levels for evaporation rate. Geostatistical analysis was used to interpolate evaporation rate and subsequently used to generate contour maps of evaporation rate for the continental U.S. Results of this analysis show that water supply rates for areas with dense poultry production including the Southeast, Delmarva Peninsula, and Iowa ranged from 3.3 to 4.2 gpm/100,000 cu. ft. air flow volume. Available on-farm data for dairy and poultry applications agreed with the estimates provided in the maps.

Technical Abstract: Evaporative cooling (EC) is an important tool to reduce heat stress in animal housing systems. Expansion of ventilation capacity in tunnel ventilated poultry facilities has resulted in increased water demand for EC systems. As water resources become more limited and costly, proper planning and design of water supply systems is critical to ensure demand is met during periods of heat stress which increase EC use and bird water consumption. Few estimates of water use in EC in animal housing applications are available in the literature and available estimates are geographically limited or rely on extreme weather events. The goal of this analysis was to provide guidance for EC water supply design to accommodate estimates of peak demand, rather than average consumption rates. Historical weather data from 732 weather stations were obtained from the National Climatic Data Center. Dry-bulb, dew point, and barometric pressure data were extracted from the records and input into psychrometric relationships to determine evaporation rate for three levels of saturation efficiency (50, 75, and 100%) to encompass the range of EC systems in use. Data from warm weather months (May through September) was used for the analysis. Simple kriging was used to spatially interpolate evaporation rate across the continental U.S. and subsequently used to generate contour maps. Frequency of occurrence values corresponding to climatic design data thresholds (2%, 1%, and 0.4%) were calculated to determine estimates of peak evaporation rates. Results of the analysis showed that EC water supply rates for areas with dense broiler production (Southeastern U.S., Delmarva peninsula) and layer production (Iowa) ranged from 4.4 to 5.6 l/min/1000 m3 (3.3 to 4.2 gpm/100,000 ft3) and encompassed the ranges of EC system water consumption data from dairy and poultry house applications.