Pulse Response Experiments and the RTD

6 = j = dimensionless time based on the mean residence time in all N tanks, t. Then 

For the first tank. Consider a steady flow v m /s of fluid into and out of the first of these ideal mixed flow units of volume V, At time t = 0 inject a pulse of tracer into the vessel which when evenly distributed in the vessel (and it is) has a concentration Cq. 

At any time t after the tracer is introduced make a material balance, thus 

Since the area under this C/Q versus t curve is (check this if you wish) it allows you to find the E curve so one may write 

For the second tank where Q enters, C2 leaves, a material balance gives 

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