General formulation of the balance equations

Let us suppose that there are several Independent chemical reactions, which are numbered, and that ft C ,T) denotes the rate of the re- 

It is often convenient to express these material balances in an alter- 

To write an unsteady state enthalpy balance we require the enthalpy per unit volume of the gas-permeated solid matrix. This is given by 

Then in terms of h and the enthalpy flux vector the enthalpy 

The quantity in brackets on the right hand side, which multiplies 

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