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Conduction Cooling Systems: Improving Production in Dairy Cattle
By moniquegarcia on Wed, 08/28/2013 - 3:01pm
Arizona currently leads the country in production per dairy cow, yet heat stress during the warmest months causes decreases in milk yield, increases in disease incidence and also increases in maintenance costs per cow. Research has shown that compared to winter months, dairy cows in Arizona produced 8.8 pounds less milk per cow per day during the summer months. At the same time, on-farm milk production has the greatest opportunity to affect the carbon footprint of a gallon of milk because dairy operations represent 80 to 95 percent of the dairy industry’s carbon footprint, and 75 percent of its electricity and fuel use. Studies at the William Parker Agricultural Research Complex, part of the University of Arizona College of Agriculture and Life Sciences, have focused on ways to minimize heat gain and maximize heat loss in dairy cattle to maintain or improve yields, while reducing water and electricity costs.
Description of Action:
In contrast to the traditional overhead electric fan systems and water misting systems that have been the norm in Arizona dairies during the hot months, UA scientists are testing a prototype conduction cooling system with an array of heat exchanger ‘panels’ installed beneath—rather than above—the cows’ bedding area in dairy barns. As well water passes through the flexible polymer-based heat exchangers, the colder temperature of the water cools the cows via conduction by transferring heat from a warm source—the cow—to a colder source—the heat exchanger-cooled bedding material installed above the panels with the colder water flowing through them.
Phase one proof-of-concept testing on the heat exchanger cooling system was conducted June 14-23, 2010 at the UA’s Agricultural Research Complex in Tucson, under the supervision of the Animal Sciences Department, followed by a commercial scale test at a 3,600-cow dairy located in Tulare, California from September 1-30, 2010. The study was funded by the Tulare Irrigation District, with the construction of the cooling arrays carried out by Ariaire, Inc., of Mesa, Arizona. The veterinary staff of the University of California, Davis and faculty from the UA Department of Animal Sciences supervised the study.
There is an approximate differential of 30 to 35 degrees Fahrenheit between the internal temperature of the cow (about 101.5 degrees F) and the temperature of the well water (about 65 degrees F) flowing through the heat exchanger panels. The target temperature range for the cow is 100 to 103 degrees F, which the test system was able to achieve until the air temperature exceeded 90 degrees Fahrenheit.
By using conduction cooling alone to cool cows up to 90 degrees F, this same 3,600-cow dairy using 180 fans at 1.2 kilowatt hours per fan and paying $.09 per kilowatt hour would save a projected $26,500 for the summer in energy costs to cool cows—a savings of over 75 percent in electricity costs. The investigators believe that if the water had been chilled by a commercial chiller the electrical costs savings still would have been substantial, and there would have been additional milk yield benefits. Researchers in the UA Department of Animal Sciences and the Department of Agricultural and Biosystems Engineering are collaborating to develop models of cooling systems that could run successfully with different water and air temperatures. Further studies using conduction cooling systems are underway in Arizona, California and Texas in 2011-2012.