Reactors for Energy Management

Note that the heat transfer rates across the wall are the same except for the sign change. The residence time of the coolant in the jacket is Tc = V c/Wc- 

We now have to solve the three algebraic equations to find Ca, T, and for 

If there is an internal cooling coil in a CSTR, the coil can exhibit a coolant temperature that is a function of position in the coil. Thus we should write a mass balance on the coolant, which is that of a PFTR without chemical reaction, 

Note that now Tj is a variable that is a function of position Zc in the cooling coif while T, the reactor temperature in the CSTR reactor, is a constant. We can solve this differential equation separately to obtain an average coolant temperature to insert in the reactor energy-balance equation. However, the heat load on the cooling coil can be comphcated to calculate because the heat transfer coefficient may not be constant. 

In this and the previous chapters we considered the effects of nonisothermal operation on reactor behavior. The effects of nonisothermal operation can be dramatic, especially for exothermic reactions, often leading to reactor volumes many times smaller than if isothermal and often leading to the possibility of multiple steady states. Further, in nonisothermal operation, the CSTR can require a smaller volume for a given conversion than a PFTR. In this section we summarize some of these characteristics and modes of operation. For endothermic reactions, nonisothermal operation cools the reactor, and this reduces the rate, so that these reactors are inherently stable. The modes of operation can be classified as follows  

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