The majority of dairies in California are located in the Central valley where summers are hot and dry. Heat stress in dairy cows remains a major cause of diminished milk production. This project developed and demonstrated at least two novel approaches to cooling dairy cows while reducing energy and water used.
Four different cooling methods were tested at a research dairy and commercial dairy: 1) Fans and sprayers operated by a simple thermostat, 2) Conduction cooling mats with chilled water supplied by a sub-wet bulb evaporative chiller, 3) Targeted convection cooling with air cooled by an evaporative cooler distributed to cows through a fabric duct and nozzle system, and 4) An optimized controller for fans and sprayers, which was based on a heat and mass transfer model of dairy cow fur-drying under varying weather conditions.
The demonstration at the research dairy concluded that conduction cooling did not adequately cool cows. The targeted convection cooling was effective at the research dairy, however, did not perform well from a cow-health perspective at the commercial dairy. The optimized controller cooled the cows as well as the baseline simple thermostat controller. The annual projection for the Central Valley shows the optimized controller would save 28 percent annual electricity relative to the commercial dairy baseline but would use 49 percent more water for the same level of thermal comfort. Baselines vary widely due to settings selected by individual dairy operators and their mechanical contractors. The benefit of the optimized controller is that it does not require any custom settings and calculates the water spray rate and fan speed to provide the necessary cooling.
