实验四 干燥操作及干燥速率曲线的测定1311.热流温度控制显示仪 12.室前温度显示仪 13.电子天平14.室后温度显示仪 15.气阀16•压差计2. 主要设备(1) 孔板流量计：管径 D = 144mm，孔径d°=68.46mm，孔截面积Ao二3皿 |Q-3m2；(2) 空气加热器：共有三组电热丝，每组功率 1000W ;(3) 湿球温度计1套；(4) 电子天平1台四、 实验步骤1. 将待测样品在烘箱中干燥至恒重，记录绝干试样的质量2. 将绝干试样放入水中浸湿，拿出稍候片刻，让水份均匀扩散至整个试样，然后称取湿试样质量3. 开启风机，调节蝶阀至预定风速，适当打开阀 15调节控温仪至预定温度(70C)4. 往湿球温度计中加水 注意加水量不能过多， 以避免溢流进入风道内 在实验过程中应注意观察蒸发情况，及时向湿球温度计中补水5. 检查天平是否正常(实验过程中一定要有专人负责固定支架，防止试验料传动丝挂到器壁，影响天平读 书的精确性)6. 待空气状态稳定后，打开干燥室门将湿试样放入7. 开动秒表，每隔一定时间记录一次干燥时间、试样质量、湿球温度、室前温度、室后温度至试样接近平 衡水份为止。
8. 实验结束，检查合格后先关加热器，再关风机，卸下试样并收拾整理现场五、 数据记录与处理绝干物料重：70.67-44.79=25.88 g 湿物料初始质量：93.5-44.79=48.71g干球温度(t ) : _95C 湿球温度(tw): 52.8C 干燥 风速： 中高档恒定~ 号 G(g) X At (s) t U[ △ W/(G*4t )]793.30.878284421.8921.890.000353037893.10.870556427.4449.330.000281632992.90.86282842372.330.0003359991092.70.855100525.7298.050.0003004661192.50.847372524.27122.320.0003184171292.30.839644516.72139.040.0004621991392.10.831916521.5160.540.0003594411491.90.824188620.1180.640.0003844761591.70.816460616.78197.420.0004605471691.50.808732618.32215.740.0004218331791.30.801004615.88231.620.0004866481891.10.793276719.63251.250.0003936821990.90.785548718.78270.030.00041152090.70.777820719.06289.090.0004054552190.50.770092719.3308.390.0004004132290.30.762364817.1325.490.0004519282390.10.754636818.87344.360.0004095382488.70.70054116.84361.20.0004589062588.50.69281317.5378.70.0004415992688.30.68508517.15395.850.0004506112788.10.67735715.75411.60.0004906652887.90.669629115.15426.750.0005100972987.70.661901119.35446.10.0003993793087.50.654173115.94620.0004860363187.30.646445115.05477.050.0005134873287.10.638717220.07497.120.0003850513386.90.630989216.05513.170.0004814943486.70.623261216.97530.140.000455393586.50.615533218.15548.290.0004257843683.50.499613622.63570.920.0003414923783.30.491885617.78588.70.0004346443883.10.484157719607.70.0004067363982.90.476429719.38627.080.000398764082.70.468701718.13645.210.0004262534182.50.460973725670.210.0003091194282.30.453245717.02687.230.0004540534382.10.445517826.13713.360.0002957514481.90.437789822.62735.980.0003416434581.70.430061823.22759.20.0003328154681.50.422333818.51777.710.0004175034781.30.414605919.32797.030.0003999994881.10.406877919.82816.850.0003899084980.90.399149924.4841.250.000316725080.70.391421922.34863.590.0003459255180.50.38369420.5884.090.0003769745280.30.37596627.13911.220.000284855380.10.36823822.31933.530.0003463915479.90.3605120.31953.840.0003805015579.70.352782122.06975.90.0003503165679.50.345054132.681008.580.0002364745779.30.337326126.091034.670.0002962045879.10.329598119.431054.10.0003977345978.90.321870220.161074.260.0003833326078.70.314142229.151103.410.0002651116178.50.306414228.651132.060.0002697376278.30.298686226.531158.590.0002912926378.10.290958329.651188.240.000260646477.30.260046436.321224.560.0002127756577.10.252318448.121272.680.0001605986676.90.244590444.691317.370.0001729246776.70.236862444.241361.610.0001746836876.50.229134560.881422.490.0001269386976.30.221406553.851476.340.0001435097076.10.213678559.621535.960.0001296217175.90.205950569.951605.910.0001104797275.70.198222663.91669.810.0001209397375.50.190494663.871733.680.0001209957475.30.182766670.541804.220.0001095557575.10.175038682.051886.279.41862E-057674.90.1673107102.591988.867.53287E-057774.70.159582795.282084.148.11081E-057874.50.151854797.532181.677.92369E-057974.30.1441267120.412302.086.41805E-058074.10.1363988120.842422.926.39521E-058173.90.1286708162.432585.354.75773E-058273.70.1209428174.512759.864.42839E-058373.50.1132148177.292937.154.35895E-058473.30.1054869247.783184.933.11889E-058573.10.0977589280.133465.062.75871E-057672.90.0900309300.323765.382.57325E-05计算举例：干燥数据处理(以第三组为例)Wio 二G9 -Gw =0.2g：10 = 16.72sX10 =[G10 -G0 (G9 -G10)/2]/G =(92.3-70.67 0.2/2)/25.88 = 0.839610 = 9 「= 139.04s4 / 6Vi04= 4.622 10 (1/s)：W 0.2G . ：. - 25.88 16.72以此类推汇总数据见附表 六、实验结果与讨论由上述数据作U~X图所得：作U~X图得:（1） 由X~T图可见，随着时间延长，干燥物料水平含量呈逐渐下降趋势。
2） 由v~X图可知，干燥速率曲线呈现升速，恒速和降速三个阶段，其特征很明显3） 对吸水硅胶而言，临界含水率 Xc=0。