THEN is a heat exchanger network synthesis program that was developed by Professor F.C. Knopf at Louisiana State University. It integrates the networks of heat exchangers, boilers, condensers and furnaces for best energy utilization. It uses thermodynamic pinch analysis as the basis for designing a network.
THEN uses pinch analysis for the optimum design of heat exchanger network. It employs three concepts: the composite curves, the grid diagram of process stream and the pinch point; and these are applied to minimize the energy use in the process. This program takes the necessary streams information from the user and decides the best arrangement of heat exchangers, heaters and coolers so that the amount of utilities needed such as cooling water and steam is minimized. It plots the Grand Composite Curve (GCC), which shows the enthalpy of the process streams as a function of temperature. It also shows the heat exchanger network design in a graphical form as the network grid diagram for visualization of the network configuration.