套管換熱器傳熱實驗實驗報告數(shù)據(jù)處理

第第1頁共7頁數(shù)據(jù)處理我們組做的是試驗I:△1，Q=mctKQ△s11 1Q=mCt,其中，C

=所以得先求m

,C，t,s11△1 1

s1 1 △11m=Vρs1 s1要得求V，V=uA，V

=CA

CC=0.855,A

為空口面s1 s1

s1 00

0 0 02gR2gR(o〕/0

的計算方法如下：A= dπ 0 4 0π

,d=20.32mm,故0A=π 20.32 2

-4m20 4×〔1000

〕=3.243293×10RπA=4d2,d20mm，用內插法求解空氣密度ρ值這樣求得m，s1

21C 的求法為先查表的相近溫度下空氣的C1度對應的的C值1△13求t=△1△1△1

t+t1 22

t為進口溫度 t1

為出口溫度進口溫度t1的求解方法 由熱電偶中的電位Vt，依據(jù)公式求E V 0.0394645t 得t t0 0 01.55741.55741031.608104EtEt，再由

490.852求得值8.04105 1出口溫度t的求解方法2 由熱電偶中的電位Vt，依據(jù)公式E V 0.0394645t 求得t t0 0 01.55741.55741031.608104EtEt，再由

490.852求得值8.04105 2由以上步驟求出Q△，由Q=KAt求出K△mK=Q△At△mQ由第一步已經(jīng)求出，A為內管內徑對應的面積，A=2πrL ,r=17.8mm=0.0178m,A=2×3.14×0.0178×1.224=0.13682362m2,求Re，Nu流體無相變強制湍流經(jīng)圓形直管與管壁穩(wěn)定對流傳熱時，對流傳熱準數(shù)關聯(lián)式的函數(shù)關系為：Nuf(Re,Pr,l)d對于空氣，在試驗范圍內，Pr準數(shù)根本上為一常數(shù)；當管長與管徑的比值大于50時，其值對Nu的影響很??；則Nu僅為Re的函數(shù)，故上述函數(shù)關系一般可以處理成：NuaRem式中，a和m為待定常數(shù)。Re=

duρμ

d=2×0.0178m=0.0356mu=Vs/〔π×0.01782〕μ和ρ用內插法，先查表的相近溫度的μ，ρ，再用線性關系計算求得。測量空氣一側管壁的中區(qū)壁溫TW，由熱電偶按前面公式求得；由下式可以計算空氣與管壁的對流傳熱系數(shù)A(T

Qt)W式中，t ——空氣進出口溫度的平均值。Nud

d=0.0356m,λ還得用內插法求解，先找到相近溫度的λ，假定λ的線性變化，求得λ。然后用以下公式：logNumlogReloglogNu-logαm= logRe可求得m,再由 NuaRem

Nua=Rem

求得對應Re，Nu下的a值。然后做 Nu/Re圖單管壓力計讀數(shù)空氣進口單管壓力計讀數(shù)空氣進口空氣出口序號R”1-2mmH2進口溫度熱電偶出口溫度計熱電偶R”0mmHg R”0mmHgO計t1〔℃〕〔mv〕〔℃〕〔mv〕由熱電偶出口電位液位高度位差計由熱電偶計計算而得 差計校正序號差(mmHg)校正讀算而得的的 讀數(shù)數(shù)4.1進口溫度Et1出口溫度t1 Et2〔mv〕2零位75.2012.0016.1026.005.9492.5024.13最高107.1055.5068.2034.506.0596.1020.901104.2050.1063.1034.506.3096.0020.802100.0045.1057.0033.906.2095.8020.80396.5040.3049.5031.005.6895.8020.75491.8035.2042.5030.106.6795.8022.05588.5030.1037.5029.806.4794.2021.86684.8025.3031.8028.006.2094.6024.10781.2020.2026.5027.506.0994.0023.94877.1015.0019.0026.706.05進口電92.8023.96t1〔℃〕1

〔mv〕 溫度〔℃)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序號蒸汽進口溫度熱電偶管壁熱電偶蒸汽kgf/cm2壓力計〔℃〕〔mv〕〔mv〕/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由熱電偶進口電位由熱電偶管壁電位計算而得差計校正計算而得差計校正序號的讀數(shù)的讀數(shù)進口溫度T1〔℃〕Et〔mv〕管壁溫度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序號平均溫度△t

ρ(Kg/m3)

Co(Kg/kg)

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序號 Vs msQΔTm(℃)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序號 K

u(m/s)

Re α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序號λ(10-*m-*)Numa零位0.029671586149.36211230.01847257124.4890676最高0.029216601244.91754410.018906679201.001631410.029243532255.69781740.018800257210.042340720.029226839240.43132340.018933132197.388976330.029132368202.32549420.019474431165.5679979Nu/ReNu/Re圖1000Nu(Nu)Nuy=0.0057x+49.81310010000Re10000040.029489779192.9038540.018534485159.794721450.029428535190.76347020.018720232157.693523660.029710712203.84365850.017924118170.121919370.029669129197.83433150.018086765164.875626180.029665342157.35078270.018516437131.1197993由計算機依據(jù)相關計算結果作出以以下圖〔雙對數(shù)坐標圖〕1、本試驗裝置承受熱電偶測溫，同時又裝玻璃溫度計，有什么必要？答：試驗是通過使用熱電偶測量，再用相關公式計算得到比較準確的相應溫度，與此同時，使用玻璃溫度計進展測量起到校正的作用，證明驗的準確性。2、本試驗裝置和操作再哪些地方簡潔造成結果誤差？如何盡量削減誤差？答：試驗中存在的誤差主要由于裝置和操作千萬的。對于裝置而言，由于其自身存在溫度，傳熱管由于老化，保濕效果不好，千萬熱損失，從而產生誤差。另外在讀數(shù)時，由于液柱R有波動，從而使Ro，Ro”,R1-2讀數(shù)不準確，這也是誤差的來源之一，為減速小認上誤差，在盡量待系統(tǒng)穩(wěn)定后再進展讀數(shù)并且改善傳熱管的保溫效果。3、蒸汽壓力的變化會不會影響試驗結果？答：會影響，由于水蒸汽在它的飽和蒸汽壓下才會僅發(fā)生相變而不發(fā)生溫變，而本試驗的T只用一個溫度，故蒸汽壓變化下T4、比較試驗所得的對流傳熱準數(shù)關聯(lián)式與流體在圓形直管中作強制湍流時的閱歷公式，兩者是否沖突？答：試驗結果與Ro,Ro”與R1-2有關，所得的對流準數(shù)關聯(lián)式與液體在圓管中作