Nonideal behaviour of a continous flow stirred tank reactor was investigated by observing the transient response of the reactor to step changes in feed concentration. It was shown that the turbulence caused by inlet flow only was sufficient for perfect mixing provided that the tank Reynolds number exceeded 17. For the tank Reynolds number below 17, mechanical stirring was necessary and the Reynolds number based on the impeller diameter for perfect mixing was correlated to the tank Reynolds number as follows:
It was also found that bypassing effects became more significant when the feedline and effluent line were placed near the liquid levels. For nonideal flows, several mixed models described the flow patterns, namely bypassing and dead space model, CSTR and PFR in series model, and dead space model.