【正文】
由于時間有點倉促,加上本人所學的知識有限,在設計中遇到很多難題,同時設計也存在很多缺點和不足,愿各位老師幫忙指導。這次設計讓我系統(tǒng)地鞏固了壓力容器、換熱器等化工設備的設計和工藝計算,并提高了查閱相關資料的能力,將是以后學習生涯中的寶貴財富。當然同時需要指導老師的悉心指導,更需要有認真負責,一絲不茍的研究態(tài)度。通過這次畢業(yè)設計,使我不但鞏固了本專業(yè)所學的知識,加強了動手能力,同時也明白了“書到用時方恨少的道理”,感受頗深。 (3)殼程壓力降的液體以交叉立方體的方式流出,為了減少壓力殼側流體下降必須減少交叉的行流。調查將會分別用數(shù)值和實驗方法繼續(xù)進行。另一個方面是操作特性,如雷諾數(shù)可兌換當?shù)貕航迪禂?shù)。因此殼下側管排線,方形排列,可表示為:,,并把它們代入方程式(4),則x方向的速度可以表示為: (15)根據方程式(7),(8),(9),壓降的x方向,xz方向和z方向在內插管束對齊殼側方向的條件也可以分別寫成方程式(16),(17)和(18): (16) 其中表示當?shù)貕航翟诠苁€一方對齊的管系數(shù) (17) (18)把(16)(17)(18)式代入方程(10)式,可簡化得到: (19)當 x = X 時,可以推導出如下的邊界條件壓降:, and 將他們代入方程(10)可得到下式: (20)聯(lián)合方程式(19)和方程式(20),簡化表達,可以推斷公式如下: (21)根據該對齊殼的管殼式換熱器管束方,最佳流體的分配比例,進口或出口區(qū)域可表示如下: (22) 從方程(15)式到方程(21), (23) (24)定義,表示管內管直徑與管間距之比,把它和方程式(23)(24)代入方程式(22),可得妻方程如下: (25)從方程式(25)看出,它已被證明是最佳的流體分配沖壓比,有關的很多因素可劃分為兩個方面。它差分方程x方向的壓力降,可表示為: (5)殼側的水力直徑,邊界條件是x = 0和Δp ( x) = 0,所以他的積分方程式(5)可以表示為: (6) (7) XZ方向的壓力降據當?shù)亓髁糠植己土鲃拥牧黧w壓力降,由x方向轉到z方向,我們可以得到如下方程的局部壓力降: (8) Z坐標的壓力降據當?shù)氐牧黧w壓降通用公式,我們可以得到它的流體通過的小型分流器擋板孔當?shù)貕航捣匠淘趜方向如下: (9) 同質分配公式眾所周知的是,同源流體通過分流器可以通過機械擋板能量平衡方程推導出進口交叉出口段的流量分布情況?;谏鲜黾僭O和下一步的分析,可以很容易地分別推導出x方向的速度分布和壓力降的x方向,z方向和xz方向。(3)在x方向流體流量,如圖所示3所示。(1)許多小孔是分布在流體擋板上,小孔直徑是微不足道的。2 數(shù)學模型為了找到了理論方法,數(shù)學模型理論分析模型,必須首先建立如圖(3)所示。該換熱器外觀尺寸是維立方體360毫米 120毫米 1 000毫米。 管殼殼端配置與軸流式換熱器示意圖1為了表達研究的物理模型更簡潔,當我們考慮到部分單位和其進口和出口唯一時,我們把它看作一個矩形熱處理軸流換熱器。(4)管間距。(2)交叉管行。該理論研究的目的是要找到一個數(shù)學模型,帶出了最佳的分布比例作為換熱器參數(shù)的函數(shù)。圖1(b) 是殼側流分銷結構圖。在這篇文章中,將介紹各種換熱器結構參數(shù)的優(yōu)化數(shù)學模型的理論方法。所以發(fā)展流體流動殼式換熱器管區(qū)理論,數(shù)值和實驗研究是非常重要的。設置流體流動分布器有優(yōu)點也有缺點。為了使流體流動同源分布,S. S. Mousavi , K. Hooman and L. Maharaj , J . Pocock , B. 。隨著換熱器的直徑的增大和長徑比的減?。↙/D),殼程流體流動分布不均變得更難以控制和殼層的壓力降增長的更快,這不僅降低了換熱器整體傳熱性能,而且也引起了傳熱管的振動。隨著工業(yè)生產設備的規(guī)模變得越來越大,換熱器作為一種工業(yè)生產通用設備,還需要滿足工業(yè)生產過程的要求,以及換熱器傳熱能力越來越大。 結構優(yōu)化。 軸向流。 (2)The boundary condition is: x = X wit h u( x) = 0 ,so t he integral of Equa. (2) can be expressed as follows : (3) (4)2. 2 Pressure drop of x coordinateThe energy balance Equation of t he infinitesimal area is shown in Fig. 4. It s differential Equation ofx direction pressure drop can be obtained as follow : (5) Where DH is hydraulic diameter of shellside.The boundary condition is x = 0 wit h Δp ( x) = 0 , so t he integral of t he Equa. (5) can be expressed as : (6) (7)2. 3 Pressure drop of x2z directionAccording to distribution and local flow pressure drop of fluid flow from x direction turn to z direction , we can obtain it s local pressure drop Equation as follow : (8)2. 4 Pressure drop of z coordinateAccording to the generic Equation of local pressure drop of fluid , we can obtain it s local pressuredrop Equation of fluid flow through mini2ostioles of distributor baffle in z direction as follow : (9) Where A ( x) denote punched ratio as a f unction of independent variable x.2. 5 Homodistribution EquationIt is well known that t he condition of homodistribution of fluid flow through distributor baffle can be deduced by mechanical energy balance Equation from inlet to cross section of outlet . The basic homodistribution Equation is shown as follow : (10) 2. 6 Analysis and solutionCombining Equa.(7) , (8) , (9) with Equa. (10) , it will obtain the following Equation : (11) When x = X ,t hen it can be deduced the pressure drop of boundary condition :, and Putting the pressure drop under x = X into Equa. (10) , then it can be deduced the following Equation : (12) Associating with Equa. (11) and Equa. (12), and simplifying expression , t hen it can be deduced the following Equation : (13) Under the ideal model, optimal punched ratio can be expressed as follow : (14)3 Mathematical Model of Inlinesquare Aligned Tube BundleFor the inlinesquare aligned tube bundle of shellside of shellandtube heat exchanger, we define as tube pitch , d as outer diameter , and L as installation distance. So tube rows of shellside under inlinesquare aligned can be expresses as ,: , and putting them into Equa. (4), then the velocity of x direction can be expressed as : (15) According to the Equa. (7), (8) , and (9) , the pressure drop of x direction , xz direction , and z direction at inlinesquare aligned condition of shellside can also be written as Equa. (16), (17) and (18) ,respectively : (16)Where denotes local pressure drop coefficient of crossing a t ube at t he inlinesquare aligned. (17) (18) Put ting Equa. (16) , (17) and (18) into Equa. (10), it can be deduced as follow. (19)When x = X , it can be deduced t he pressure drop of boundary condition as follow :, and And p ut ting t hem into Equa. (10) , then it can be deduced the following Equation : (20)Associating with Equa. (19) and Equa. (20), and simplifying expression , t hen it can be deduced following Equation : (21) Under the inlinesquare aligned tube bundle of shellside of shellandtube heat exchanger, optimal punched ratio of