Untitled - Aerobib - Universidad Politécnica de Madrid

6.7. REACTION VELOCITY 145
1.0
0.8
Y(L=2)
θ, ε, Y
0.6
0.4
0.2
θ 0
θ
Y(L=0.5)
Y(L=1)
ε
0.0
−10 −8 −6 −4 −2 0 2 4 6 8 10
ξ
Figure 6.4: Distributions of Y , ε and θ as functions of ξ, when the activation energy is zero.
b) Heating zone.
Likewise, in this zone one obtains
θ = θ 0 + (θ i − θ 0 ) e ξ , (6.52)
Y = 1 L
θ i − θ 0
(1 + 1 ) −1
θ i − θ 0
e Lξ , (6.53)
1 − θ i L 1 − θ i
ε = 0. (6.54)
Figures 6.3 and 6.4 represent the solutions computed for the following typical
values: θ 0 = 0.125, θ i = 0.4 and L = 0.5, 1 and 2.
6.7 Reaction velocity
The correct expression for the reaction velocity w is, in accordance with the laws of
Chemical Kinetics, 3 w = ρ n k(1 − Y ) n . (6.55)
3 See Chap. 1, §8.