Process Control: Modeling, Design, and Simulation

2.2. Balance Equations

In this text, we are interested in dynamic balances that have the form

This equation is deceptively simple because there may be many in and out terms, particularly for component balances. The in and out terms would then include the generation and conversion of species by chemical reaction, respectively. The rate of mass accumulation in a system has the form dM/dt, where M is the total mass in the system. Similarly, the rate of energy accumulation has the form dE/dt, where E is the total energy in a system. If N_i is used to represent the moles of component i in a system, then dN_i/dt represents the molar rate of accumulation ...