In the general balance equation, which term is zero at steady state operation?

In the general balance equation, which term is zero at steady state operation?

• A. Inflow
• B. Outflow
• C. Reaction
• D. Accumulation

Answer: (D)

At steady state, the amount stored in the system does not change with time, so the accumulation term is zero. In the general balance, accumulation represents how the inventory inside changes per unit time, and it is described by dN/dt (or a similar rate of change). The balance can be written as dN/dt = r_in − r_out + r_gen − r_cons. When the system runs at steady state, dN/dt = 0, so the accumulation term vanishes. This means material can be flowing in and out and reactions can be producing or consuming species, but the net change in inventory is zero.

At steady state, the amount stored in the system does not change with time, so the accumulation term is zero. In the general balance, accumulation represents how the inventory inside changes per unit time, and it is described by dN/dt (or a similar rate of change). The balance can be written as dN/dt = r_in − r_out + r_gen − r_cons. When the system runs at steady state, dN/dt = 0, so the accumulation term vanishes. This means material can be flowing in and out and reactions can be producing or consuming species, but the net change in inventory is zero.