给热系数的测定实验数据记录文稿和处理

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1、实验数据记录与处理1、实验原始数据记录表次序项目123456789水蒸气压强MPa0.020.020.020.020.020.020.020.020.02空气进口温度t1°C32.730.328.024.622.121.420.82121.6空气出口温度t2°C74.172.971.970.770.470.771.972.674空气进口处蒸汽温度T1°C103.2103.2103.2103.2103.2103.2103.2103.2103.2空气出口处蒸汽温度T2°C102.3102.3102.3102.3102.310

2、2.3102.3102.3102.3空气流量V（m3/h）23.022.021.018.515.012.6108.57空气进口处密度ρ（kg/m3）1.15511.16441.17341.18691.19701.19981.20231.20151.1982空气质量流量ms（kg/s）0.00740.00710.00680.00610.00500.00420.00340.00280.0023空气流速u（m/s）31.791830.409629.027325.571720.733817.416413.822511.74929

3、.6758计算公式：①空气进口处密度：②空气质量流量：③空气流速：2、给热系数K的计算次序项目123456789空气定性温度t平均°C53.4051.6049.9547.6546.2546.0546.3546.8047.90定性温度下的空气密度kg/m31.07981.08601.09181.09991.10481.10571.10451.10291.0989冷、热流体间的对数平均温差°C46..443548.179249.701451.857753.014553.071752.456451.885850.5873总给热

4、系数Kw/(m2·°C)151.704125.962120.948108.55990.97278.10065.13356.48248.132计算公式：①空气定性温度：（）②空气比热：J/(kg·°C)③定性温度下的空气密度：=④冷、热流体间的对数平均温差：⑤传热面积：⑥对流传热系数：3、近似法求给热系数hh=K=103.1096w/(m2·°C)4、h理论值的计算次序项目123456789对流给热系数hw/(m2·°C)151.704125.962120.948108.55990.97278.10065.13356.48

5、248.132空气黏度μ（Pa·s)1.87821.86651.85531.83871.82641.82301.82001.82101.8249空气导热系数λW/(m·K）0.02700.02680.02660.02630.02620.02610.02610.02610.0261雷诺数Re29243283092732924474200681689913421113659332普兰特数Pr0.69970.69990.70030.70110.70170.70180.70200.70190.7017努赛尔数Nu78.06337

6、6.166572.684065.901355.644447.872339.997034.663029.4673努赛尔数理论值Nu'74.643472.654670.659164.717255.232848.143840.041035.102229.9122理论h'W/(m2·°C)125.767121.722117.577106.60590.30078.54365.20557.19748.859h各点的相对误差%-4.72-3.48-2.86-1.82-0.740.560.111.251.481.95461.93811.

7、92331.88061.80701.71461.66351.60131.53094.46604.45194.43664.38884.30254.22794.12784.05633.96计算公式：①空气粘度：①空气导热系数：②雷诺数：③普兰特数：④努赛尔数：⑤对于流体在圆形只管内做湍流时的对流传热系数若符合以下条件：，，管长与管内径之,则本实验中，,而Re，Pr也基本在这个范围内，n=0.4。所以可以用上述公式计算Nu的理论值：⑥理论给热系数：⑦相对误差：实验结果与分析1、冷流体给热系数的实验计算值与理论值（）列表比较，计

8、算各点误差，并分析讨论次序项目123456789努赛尔数Nu78.063376.166572.684065.901355.644447.872339.997034.663029.4673努赛尔数理论值Nu'74.643472.654670.659164.717255.232848.143840.041035.1022