套管换热器传热实验实验报告数据处理

套管换热器传热实验实验报告数据处理我们组做的是实验I:1，Q=ms1c1△t1求K得先求QQ=ms1C1△t1,其中，C1=所以得先求ms1,C1，△t1,◇1ms1=Vs1ρ要得求Vs1，Vs1=u1A，Vs1=C0A0/o(2）gRC0为空流系数，C0=0.855,A0为空口面积，A0的计算方法如下：A0=π4d02,d0=20.32mm,故A0=π4×（20.321000）2=3.243293×10-4m2R为压计差读数A=π4d2,d为内管内径=20mm，用内插法求解空气密度ρ值这样求得ms1，◇2C1的求法为先查表的相近温度下空气的C值，然后用内插法求得对应平均温度对应的的C1值◇3求△t1=t△t1,=t=t1+t22t1为进口温度t2为出口温度进口温度t1的求解方法由热电偶中的电位Vt，按照公式求20000000402.00394645.0ttVEtt得Et，再由852.4901004.810608.1105574.1543tEt求得t1值出口温度t2的求解方法由热电偶中的电位Vt，按照公式20000000402.00394645.0ttVEtt求得Et，再由852.4901004.810608.1105574.1543tEt求得t2值由以上步骤求出Q2，由Q=KA△tm求出K值K=QA△tmQ由第一步已经求出，A为内管内径对应的面积，A=2πrL,r=17.8mm=0.0178m,A=2×3.14×0.0178×1.224=0.13682362m23,求Re，Nu流体无相变强制湍流经圆形直管与管壁稳定对流传热时，对流传热准数关联式的函数关系为：(,,)lNufRePrd对于空气，在实验范围内，Pr准数基本上为一常数；当管长与管径的比值大于50时，其值对Nu的影响很小；则Nu仅为Re的函数，故上述函数关系一般可以处理成：mNuaRe式中，a和m为待定常数。Re=duρμd=2×0.0178m=0.0356m,u=Vs/（π×0.01782）μ和ρ用内插法，先查表的相近温度的μ，ρ，再用线性关系计算求得。测量空气一侧管壁的中区壁温TW，由热电偶按前面公式求得；由下式可以计算空气与管壁的对流传热系数()WQATt式中，t——空气进出口温度的平均值。dNud=0.0356m,λ还得用内插法求解，先找到相近温度的λ，假定λ的线性变化，求得λ。然后用以下公式：logNumlogRelogm=logNu-logαlogRe可求得m,再由mNuaRea=NuRem求得对应Re，Nu下的a值。然后做Nu/Re图用计算机软件计算的数据汇总如下：序号单管压力计读数空气进口空气出口R'1-2mmH2OR'0mmHgR'0mmHg进口温度计t1（℃）热电偶（mv）出口温度计（℃）热电偶（mv）零位75.2012.0016.1026.005.9492.5024.13最高107.1055.5068.2034.506.0596.1020.901104.2050.1063.1034.506.3096.0020.802100.0045.1057.0033.906.2095.8020.80396.5040.3049.5031.005.6895.8020.75491.8035.2042.5030.106.6795.8022.05588.5030.1037.5029.806.4794.2021.86684.8025.3031.8028.006.2094.6024.10781.2020.2026.5027.506.0994.0023.94877.1015.0019.0026.706.0592.8023.96序号液位高度差(mmHg)由热电偶计算而得的进口电位差计校正读数由热电偶计算而得的出口电位差计校正读数4.1进口温度t11（℃）Et1（mv）出口温度t21温度（℃)Et2（mv）零位12.729.231.1880109.96264.826最高1329.751.210096.43714.18111.930.941.260096.01344.1629.230.471.240096.01344.1637.327.981.136095.80154.1547.432.711.3340101.28814.4156.531.751.2940100.48944.37266.330.471.2400109.83844.827429.941.2180109.17544.788829.751.2100109.25834.792序号蒸汽管壁蒸汽kgf/cm2进口温度计（℃）热电偶（mv）热电偶（mv）压力/cm2零位111.0025.1525.500.60最高110.0024.0023.900.581110.0023.8023.700.592109.8023.7023.800.553109.9023.8023.780.574110.0023.9024.920.595109.5025.0324.800.556110.2024.9024.830.607110.0024.9124.770.558110.0024.8724.770.53序号由热电偶计算而得的进口电位差计校正读数由热电偶计算而得的管壁电位差计校正读数进口温度T1（℃）Et（mv）管壁温度Tw（℃）Etw（mv）零位114.175.03115.615.1最高109.424.8109.014.781108.594.76108.184.742108.184.74108.594.763108.594.76108.514.7564109.014.78113.224.9845113.685.006112.734.966113.144.98112.854.9667113.184.982112.614.9548113.024.974112.614.954序号平均温度△t内插法平均温度对应的密度ρ(Kg/m3)内插法求比热Co(Kg/kg)内插法求黏度μ(10-5Pa*s)零位69.594090311.030258321.0172.057970452最高63.094294861.0504076861.0172.025471474163.479029881.0492150071.0172.027395149263.240555791.0499542771.0172.026202779361.890969351.0541379951.0172.019454847466.996847161.0383097741.0172.044984236566.121927041.0410220261.0172.040609635670.15303531.0285255911.0172.060765176769.558984871.0303671471.0172.057794924869.504892451.0305348331.0172.057524462序号VsmsQΔTm(℃)零位0.0107484280.011073657783.762359126.86818878最高0.0187347980.0196791761262.75164636.7621040110.0189655540.0198989431284.63943735.7520878320.0181390430.0190451661224.90215535.3470686530.0159173690.0167791031056.12902536.8441148840.0142864410.0148337511010.70941929.9392596850.014365210.0149545011005.6303437.6326396160.0135448820.013931258993.934445924.6506423770.0133229490.013727529971.10582226.119738780.0106151160.010939247773.256813825.66768145序号Ku(m/s)Reα零位213.198887810.7539367219165.69048124.4890676最高251.047850518.7443993534606.15001201.00163141262.614538618.9752734234959.41296210.04234072253.271847718.1483397333479.14658197.38897633209.501807415.9255262929594.23455165.56799794246.731261414.2937628525836.49211159.79472145195.304661714.372572726102.64383157.69352366294.692052913.5518236324078.77196170.12191937271.729414713.3297770823760.89503164.87562618220.179072610.6205564318937.16389131.1197993序号λ(10-2*m-1*℃)Numa零位0.029671586149.36211230.01847257124.4890676最高0.029216601244.91754410.018906679201.001631410.029243532255.69781740.018800257210.042340720.029226839240.43132340.018933132197.388976330.029132368202.32549420.019474431165.567997940.029489779192.9038540.018534485159.794721450.029428535190.76347020.018720232157.693523660.029710712203.84365850.017924118170.121919370.029669129197.83433150.018086765164.875626180.029665342157.35078270.018516437131.1197993由计算机根据相关计算结果作出下图（双对数坐标图）Nu/Re图y=0.0057x+49.813100100010000100000ReNuNu线性(Nu)1、本实验装置采用热电偶测温，同时又装玻璃温度计，有什么必要？答：实验是通过使用热电偶测量，再用相关公式计算得到比较准确的相应温度，与此同时，使用玻璃温度计进行测量起到校正的作用，证实验的精确性。2、本实验装置和操作再哪些地方容易造成结果误差？如何尽量减少误差？答：实验中存在的误差主要由于装置和操作千万的。对于装置而言，由于其自身存在温度，从而引起测量的不准确。以及在进行热电偶测温时，读数也会产生细微误差。更为主要的是传热管由于老化，保湿效果不好，千万热损失，从而产生误差。另外在读数时，由于液柱R有波动，从而使Ro，Ro',R1-2读数不精确，这也是误差的来源之一，为减速小认上误差，在尽量待系统稳定后再进行读数并且改善传热管的保温效果。3、蒸汽压力的变化会不会影响实验结果？答：会影响，因为水蒸汽在它的饱和蒸汽压下才会仅发生相变而不发生温变，而本实验的T只用一个温度，故蒸汽压变化下T会不准确造成实验影响。4、比较实验所得的对流传热准数关联式与流体在圆形直管中作强制湍流时的经验公式，两者是否矛盾？答：实验结果与Ro,Ro'与R1-2有关，所得的对流准数关联式与液体在圆管中作强制湍流的经验公式不矛盾。因为其中有少许误差都是人为和设备引起的，但大方向上它们是一致的。5、对比实验所得的螺旋槽管与圆形光滑管内的对流传热准数关联式，可以说明什么问题？答：对比后发现，螺旋管的水α以及Nu都比光滑管高证明加剧湍动的剧烈程度可使传热效果