Govt. Exams
Entrance Exams
A very small external mass transfer coefficient creates a large resistance to diffusion from bulk to particle surface, making external mass transfer the rate-limiting step.
Peclet number Pe = uL/D. High Pe means low diffusion relative to convection, approaching ideal PFR behavior with narrow RTD.
Both equations are valid: the integral formulation and the volumetric flow definition give the same mean residence time.
By selectively removing product through the membrane, the equilibrium constant expression is displaced, allowing conversion beyond the thermodynamic limit.
Semi-batch allows controlled feeding of reactants, limiting instantaneous heat generation while maintaining good mixing and temperature control.
Sintering involves migration of metal atoms on the catalyst surface, leading to agglomeration and reduction of active surface area, particularly at high temperatures.
For equal volume CSTRs in series processing first-order reaction: C = C₀/(1+kτ)ⁿ, showing exponential decrease in concentration.
Continuous feeding of A reduces the instantaneous reaction rate and heat generation, allowing better temperature control and potentially reducing side reactions.
At equilibrium: Ke = [B]/[A] = 4. If initial [A]₀ = C, then at equilibrium: 4 = X/(1-X), solving X = 0.8 or 80%
Higher inlet temperature increases reaction rate (via Arrhenius equation) in an exothermic reaction, leading to higher conversion. Heat removal capacity depends on coolant flow and ΔT.
