MU researcher develops more efficient way to heat poultry barns
In a chance discussion with a poultry farmer in 2009, Shawn Xu was shocked to learn about the vast amounts of propane used to heat turkey and chicken facilities. Xu, an associate research professor of civil and environmental engineering at the University of Missouri, had worked prolifically with ground source heat pumps and geothermal energy — including serving as an energy adviser during construction for the 2008 Summer Olympics in Beijing — and decided then and there to shift his focus to agriculture. He first devised a geothermal system for poultry farms, and now has turned his focus to waste heat recovery.
“I realized, there’s a strong ventilation in the barn, and that heating continues for 24 hours,” Xu said. “The inside of the barn’s 80, 90 degrees. If you stand in front of the fan, that’s warm air coming out of the barn. I said, ‘Why don’t we use that?’”
Xu — alongside his brother and research associate Tingsheng Xu, whom he credits for prototyping and field testing the system — developed a waste heat recovery system to make heating of poultry barns more even, more efficient, and perhaps most importantly, more cost effective by driving down the amount of propane required to heat the barns in the winter. The Midwest features some of the nation’s top poultry producing states, and temperatures get predictably cold in the winter. Unlike previous systems, Xu’s waste heat recovery system captures about 60 percent of the exiting warm air to pre-warm the incoming air, meaning the heaters don’t have to expend as much energy and use as much propane to heat the air in the barn. Depending on the type of bird and the birds’ ages, barns typically are kept anywhere from 65 to 90 degrees year-round.
“I started working with the University of Arkansas. We precisely figured out how much of the heat goes through your roof, losses through your wall, and how much is wasted through your ventilation,” Xu said. “About 80 percent goes through the ventilation. That really made me excited [about the possibilities of the new system].”
Xu — along with co-investigators Tingsheng Xu and Robert Reed, an associate research professor of civil engineering — presented early findings from two types of barns at the Midwest Poultry Federation Convention, held in March in St. Paul, Minn.
In the first test, Xu looked at two broiler barns in which eight heat recovery units were installed and compared them to two with conventional heating systems. After two years, his data showed propane savings of between 45 and 50 percent using the waste heat recovery units, with variations based on weather patterns and operations.
The second field test began operating at a turkey barn in December 2014, Early on, however, Xu said the system helps eliminate a cold spot prevalent in turkey barns. Turkey barns use a drop curtain in place of a solid wall for proper ventilation, but air entering via loose fitting curtains can create pockets of cold spots, forcing the turkeys to congregate in a smaller area. Farmers often have to adjust the curtain day and night to avoid this.
Because the system is designed to run continuously, and variable speed drivers allow farmers to set the amount of fresh air needed, the system helps eliminate the need for constant adjustments by providing a more even temperature throughout the facility. The system also has a timed flushing system to remove the dust, feathers and other airborne items that can get trapped and clog the system.
Next up for Xu is convincing more farmers to adopt his system and attracting investors, which will allow him to produce more units, continue to improve on the design of the units and collect more supportive data. He is discussing the research with Missouri Department of Agriculture’s Poultry Task Force and several farmers throughout the Midwest, including members of the Midwest Poultry Federation.
Also on tap is a grant from the USDA to study further Xu’s preliminary hypothesis that the waste heat recovery system improves the air quality in the barns by lowering the amount of carbon dioxide, ammonia and moisture, as well as helping create bigger and healthier birds overall. Farmers in Missouri, Minnesota and Nebraska have committed to using the system for field testing, which also would be covered by the USDA grant.
“We have a strong reason to believe that in the future, we can use this system to improve the mortality rate,” Xu said. “Still, we just have a few barns under observation, so the next grant should help us to verify those numbers.”