Effects Of Bulk-curing Heat Exchanger Material And Structure On Tobacco Leaf Curing

Nonmetallic refractory smooth tube heat exchanger, metallic smooth tube heatexchanger and metallic fin tube heat exchanger were used as treatments to explore the effect ofmaterial and structure of bulk-curing barn heat exchanger on flue-cured tobacco curing. In theyear2009and2010, experiments on material and structure of heat exchanger was carried out inWu Yishan, Fujian. Results were as following：1. Temperature rising and sustaining behavior of heat exchanger with different material andstructure. Under loaded and unloaded conditions, bulk-curing barn with metallic fin tube heatexchanger performed the best in temperature rising, and bulk-curing barn with metallic smoothtube heat exchanger followed, that with nonmetallic refractory smooth tube heat exchangerbehaved relatively poorer. However, temperature holding behavior of them showed as bulk-curing barn with nonmetallic refractory smooth tube heat exchanger> bulk-curing barn withmetallic fin tube heat exchanger> bulk-curing barn with metallic smooth tube heat exchanger.2. Temperature and moisture distribution of heat exchanger with different material andstructure. Trends of level and vertical temperature difference were varying among bulk-curingbarns with different heat exchanger. Two peaks existed in level temperature difference duringcuring, and in the whole curing process, barn with nonmetallic refractory smooth tube heatexchanger gain least level temperature difference, barn with metallic fin tube heat exchanger camethe second, while barn with metallic smooth tube heat exchanger were the biggest. Verticaltemperature difference generally took inverted “W” form. Nonmetallic refractory smooth tubeheat exchanger could reduce vertical temperature difference in yellowing stage and leaf–dryingstage, while metallic smooth tube heat exchanger could reduce it in stem-drying stage.3. Temperature and speed of heated air within curing barn at different measuring points.When heated air went through a layer of tobacco leaf, its temperature dropped. Air temperature atair return opening dropped to different extent compared to that at air inlet. Among differentmeasuring points, speeds of heated air were air inlet> air return opening> leaf tip of layer2> leaftip of layer3. Speed of heated air at all measuring points of barn with metallic fin tube heatexchanger were the biggest compared with the other treatments. In the whole curing process,speed heated air in barn with refractory nonmetallic smooth heat exchanger changed the least.4. Effects of heat exchanger with different material and structure on the quality of curedtobacco leaf. Metallic fin tube heat exchanger and refractory nonmetallic smooth tube heatexchanger could improve appearance quality of tobacco leaf, and metallic fin tube heat exchanger performed better. Little difference existed among routine chemical component of differenttreatment. As to middle tobacco leaf, refractory nonmetallic smooth tube heat exchanger couldimprove contents of Degraded Carotenoid Products, Phenylalanine Products, CemdrenoidProducts, but it went against accumulation of Neophytadiene, while metallic fin tube heatexchanger could do some help for the accumulation of Maillard Reaction Products, and metallicsmooth tube heat exchanger was good for increasing of the content of Neophytadiene and totalneutral aroma components. As to upper leaf, refractory nonmetallic smooth tube heat exchangercan increase the content of Phenylalanine Products, but went against the accumulation ofDegraded Carotenoid Products, However, metallic fin tube heat exchanger could improve theaccumulation of Degraded Carotenoid Products and Maillard Reaction Products. Metallic fin tubeheat exchanger and refractory nonmetallic smooth heat exchanger could improve smoking qualityof tobacco leaf, and metallic fin tube heat exchanger performed better.5. Metallic fin tube heat exchanger and refractory nonmetallic smooth heat exchanger couldreduce energy consumption and curing cost as well as improve thermal efficiency of bulk-curingbarn, and Metallic fin tube heat exchanger took the best effect. Refractory nonmetallic smoothheat exchanger and metallic smooth tube heat exchanger can improve economic traits of curedtobacco.