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The Nonisothermal Stirred Tank

The locus classicus of this important principle for chemical engineers is the nonisothermal stirred tank in which a single reaction takes place (for multiple reactions, see pp. 16-17). Consider the reaction [Pg.18]

We will leave the further reduction of these S equations until later and turn to the equation for temperature. Again, it is important to realize that an equation for T cannot be written down immediately, but must be derived from the balance of some form of energy, here the enthalpy. Let hj(T) be the enthalpy per mole at temperature T (we will ignore the dependence on c for the moment), so that the total enthalpy of the reacting mixture is H = VSy [Pg.18]

and the net flux F = q 2S[ cjfhj Tf) - Cjhj(T). As for the generation of enthalpy, it is represented only by the external heating or cooling. One does not put in a term for the rate of generation of heat by reaction that falls out naturally from the rearrangement of the enthalpy. Let G = Q(T) then [Pg.19]

Now (dhj(T)ldT) = cpj is the heat capacity per mole of Aj, and the second term on the left-hand side of this equation could be written 0Cp(dTldt), where Cp is the total heat capacity per unit volume. Also, by multiplying each of the equations in (57) by the corresponding hj and subtracting from (59), we have [Pg.19]

We should ask what difference it would make if the dependence of hj on the concentrations were taken into account. Quite obviously, it would have given us a rather messy term in addition to the two on the left-hand side of Eq. (59), [Pg.19]


See other pages where The Nonisothermal Stirred Tank is mentioned: [Pg.18]    [Pg.28]   


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