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Chapter 25

輸 送 現 象. Chapter 25. 質傳 方程式 Differential Equations of Mass Transfer. Differential Equation of Mass Transfer (1). Differential Equation of Mass Transfer (2). 輸 送 現 象. Mass transfer Equation. U O T P. 與 (Fourier field equation) 比較. 熱擴散係數 m 2 /s α = k / (ρ c P ). 輸 送 現 象.

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Chapter 25

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  1. 輸送現象 Chapter 25 質傳 方程式 Differential Equations of Mass Transfer

  2. Differential Equation of Mass Transfer(1)

  3. Differential Equation of Mass Transfer(2)

  4. 輸送現象 Mass transfer Equation

  5. UOTP 與(Fourier field equation)比較 熱擴散係數 m 2/s α = k / (ρ cP)

  6. 輸送現象 界面質傳( Boundary Condition) • 界面濃度 • 液相純質 • 液相溶液 • 氣相液相成分一致，通常AB有一定濃度 依Roult’s Law • 氣相液相成分不同，通常A為稀薄溶液濃度依 Henry’s Law A 液相 氣相 Uni-component A 液相 氣相 B A A B 液相 氣相 C

  7. 輸送現象 Equimolar Diffusion in gas PA1 PB1 P PA2 PB2 P JA JB P PA1 PB2 PA2 PB1 z

  8. 輸送現象 Example o1 A- NH3 B-N2 求 PA1=1.013*104Pa PB1=? P=1.0132*105Pa PA2=0.507*104Pa PB2=? P=1.0132*105Pa JA JA=? JB=? NA =? 0.1m JB DAB(of NH3-N2) =0.23*10-4m2/s

  9. 輸送現象 Mass Flux of Equimolar NA NB yA yB2 yAi yB zT

  10. 輸送現象 Diffusion of A through stagnant (Uni-component Diffusion) PA2 2 1 NA A:NH3 B:Air NA PA1 1 2 B:Water A:Bezene

  11. 輸送現象 yA2= yA1= PA1 /P PA2 /P Example o2 PA2=0 PA1為293K 水 飽和蒸汽壓 求 J*A=? • DAB(of H2O-Water)=0.25*10-4m2/s • P=1.01325*105 Pa • C= 2 PA2 NA 0.152m B:Air PA1 1 A:Water 293K

  12. 輸送現象 Diffusion of A through stagnant (Uni-component Diffusion) C:Solvent A: Ethanol B: Water NA

  13. 輸送現象 Example o3 T=293K （水＋酒精）溶液中，水不溶於有機溶劑C 酒精藉由2mm薄膜向介面擴散 ρ1=972 xA2=6.8wt% ρ2=988.1 xA1=16.8wt% • DAB(of H2O-Alc)=0.74*10-9m2/s C:Solvent 求 1 A: Ethanol B: Water NA 2

  14. Example 25-1 NA NB =-2NA

  15. Example 25-2 NA NB =-2NA

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