Relaxation and chemical times

The relaxation time may be further interpreted as containing contributions from flow (tres) and chemistry (tchiSS). Then 

The sign of fch, ss is determined by the sign of the factor (a0 + b0 — 3ass), which may be either negative or positive. The sign and value of the relaxation time and the eigenvalue also then depend on the value of the particular stationary-state concentration of A. 

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