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47th TWC, Tob. Work. Conf., 2016, abstr. 18

Evaluation of a flue-cured tobacco bulk barn exhaust air heat recovery system

MACIALEK J.A.; ELLINGTON G.H.
North Carolina State University, Raleigh NC USA

Recovering the waste heat during the curing process for flue-cured tobacco has been researched in the past utilizing the energy in the exhaust air to preheat the colder intake air. The exhaust air vented from a curing barn can range in temperature from 100 to 165oF and range in relative humidity from 15 to 90%. The exhaust air heat recovery system utilized during the 2014 and 2015 season reassess the economic feasibility of this strategy primarily due to increased airflow and leaf capacities of modern barns and current fuel prices. The system consisted of a heat exchanger (recovery coil) in the exhaust air stream at the front of the barn connected to an additional heat exchanger (preheat coil) in the fresh air stream located in the rear of the barn. A fractional horsepower pump circulates water between the two heat exchangers in a closed loop system. Fuel and kilowatt-hour meters were installed to monitor the total energy usage from the barn implemented with the system and an identical make barn without the system for direct comparisons. Spatial air temperature data was collected along with water temperatures to assess the system performance. Averaged over ten cures during the 2014 season, the barn implemented with the heat recovery system consumed approximately 228 gallons of LP gas per cure compared to 278 gallons for the check barn. An additional benefit of the heat recovery system is that the burner cycles on and off fewer times extending the life of the heat exchanger and burner. (Reprinted with permission)