结果表明:增加谐振腔长度可增加等宽高矩形谐振腔的谐振频率模式数目,提高微波场均匀性;90 cm×90 cm×100cm矩形谐振腔具有242个谐振频率模式;在千燥室上、下壁面对角交叉、均匀布置微波馈口可保证回转干燥的均匀性;采用筛底载料盘或降料层厚度,均可缩短物料颗粒蒸发水分的迁移路径,提高干燥速度,缩短干燥时间.以胡萝卜为例,在装载量为4kg、微波功率为4 kW、真空度为0.08 MPa时,采用筛底载料盘所需的干燥时间比采用实底载料盘缩短约10 min;料层厚度每增加2 cm,干操时间增加约10 min.%Results showed that increasing the length of resonant cavity could increase the number of resonant frequency mede of resonant cavity with equal width and height and improve the uniformity of microwave filed. 90 cm ×90 cm × 100 em rectangular resonant cavity had 242 resonant frequdncy modes. Microwave entrances diagonally and equally distributed on upper and lower surface of resonant cavity guaranteed the material drying uniformity. Using sieved plate or decreasing load thickness could shorten the moisture migration distance of the moisture evaporated from material granules, and increase drying rate and decrease drying time. Using carrot as trial material with the 1cad of 4 kg, the microwave power of 4 kW and the vacuum of 0.08 MPa, the drying time could he shortened about 10 rain while using sieved plate compared with normal plate. Drying time would be increased about 10 min while load thickness increased 2 cm.
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