多孔催化剂有效因子的近似分析解——(I)近似计算式

在Thiele模数很大和很小的情况下,运用摄动法可求等温下一维催化剂颗粒有效因子的渐近解.利用这两个渐近解的信息,得到一新的有效因子近似计算式:n=a_1(thφ/φ)+a_2(thφ/φ)~2+…+a_a(thφ/φ)~a该式在整个Thiele模数范围内有效,与一级反应精确解相比较,其精度十分令人满意.该式的假设考虑了系统的物理本质,因而克服了以往文献中近似式的种种不足,使之能可靠又方便地应用于实际计算.

Approximate Analytical Solutions of EffectivenessFactor for Porous Catalysts( I )A New Expression

For the one-dimensional catalyst pellets, the perturbation method can be employed to get asymptotic solutions of isothermal heterogeneous diffusion-reaction equations with arbitrary kinetics when Thiele moduli are small or large. From the asymptotic solutions, a new analytical expression of effectiveness factorvalid throughout the whole range of Thiele modulus is obtained. Compared with the exact analytical solutions of first order irreversible reaction, the approximate solutions are satisfactory in a larger scope.