Restrictions on permissible paths for changing efficiencies of operation of flow reactors.

Sometimes a continuous flow stirred tank reactor can exhibit two or more different states of chemical reaction for the same flow rate. If such a situation is possible, a state of low reactive efficiency can be converted to one of higher efficiency by first decreasing the flow rate and then increasing it to the original value. This transition can never be accomplished by first increasing and then decreasing the flow rate. Similarly, a state of high reactive efficiency can be converted to one of lower efficiency only by first increasing and then decreasing the flow rate. These restrictions on permissible order of operations seem to differ from restrictions on efficiencies of cyclic heat engines and on directions of chemical change in closed systems as derived previously from thermodynamics.