Lecture 27 - University of Michiganelements/5e/powerpoints/2013lectures/Lec... · 2019. 8. 7. ·...
Transcript of Lecture 27 - University of Michiganelements/5e/powerpoints/2013lectures/Lec... · 2019. 8. 7. ·...
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Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of
chemical reactions and the design of the reactors in which they take place.
Lecture 27
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Web Lecture 27 Class Lecture 23
How Reaction Rate Varies with: 1. Temperature 2. Catalyst Particle Size 3. Eternal Flow Rate
For A. Reaction Rate Limited Reactors B. Internal Diffusion Limited Reactions C. External Rate Limited Reactions
And all 9 combinations of numbers and letters, Eq. 1A, 1B, 1C, 2A, 2B, 2C and 3A, 3B and 3C.
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Internal Diffusion How will we know these trends discussed in the last slide:
1. Solve the diffusion and reaction equation for catalyst particle for concentration gradient
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CA =CA0λ
Sinh Θ1λ( )Sinh Θ1
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2. Find the true rate of reaction as a function of the external and internal surface reactions.
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Internal Diffusion
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D ~ T1.75
kr ~ e−E RT
− "rA =3R
Dekr kr =
3R
De kr
− "rA =~ D0.875e−E 2RT
=
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Surface Reaction
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−rA = krCA = k1 expER1T1−1T
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#$
%
&'
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#$$
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&''
− "rA
U
− "rA
dp
− "rA
T
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and − rA = −knCAn
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The Thiele modulus for this first order reaction is
For a first-order reaction, Equation (15-19) becomes
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Figure E15-1.1 Damaged cartilage. (Figure courtesy of Newsweek, September 3, 2001.) 22
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Diffusion of O2 around collagen
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A0
A
CC ,
Lz == ψλ
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