Temperature Difference Between Bulk Fluid and Catalyst Surface

4 Temperature Difference Between Bulk Fluid and Catalyst Surface 

The mass- and heat-transfer coefficients kc and h can be written in terms of the Colburn y-factors for mass and heat transfer jo and jn, respectively  

In these expressions, Sc is the Schmidt number, Pr is the Prandtl number, Cp,m is the mass heat capacity (energy/mass-temperature), G is the superficial mass velocity (mass/area-time), and is the mass-transfer coefficient when the net molar flux is zero. The difference between kc and will be discussed in more detail later in this section. Temporarily, we wiU 

The ratio Sc/Pr is the Lewis number (Le), introduced in Section 9.3,7. The quantity (—AHR)CA,B/pcp,m is the adiabatic temperature change (ATad). For many types of reactor and regimes of flow, the Chilton-Colbum analogy between heat and mass transfer leads to 7h/./d = 1- Introducing these simplifications reduces the above equation to 

Equation (9-47) shows that the temperature difference between the bulk fluid and the surface of the catalyst particle is directly proportional to the concentration difference between these points. As Ca,b — Ga,s becomes larger, so does Ts — Tb. 

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The same reasoning suggests that there will be a temperature difference between bulk fluid and catalyst surface. Its magnitude will depend on the heat-transfer coefficient between fluid and catalyst surface, the reaction-rate constant, and the heat of reaction. If the reaction is endothermic,... 

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