Selection of optimal pipe diameters in a district heating network using minimisation of annual total energy and exergy consumption

The determination of optimal pipe diameters in a district heating network was conducted using minimisation of annual total energy and exergy consumption. At first, the district heating pipe diameters under the maximum load condition was sized based on a range of target pressure losses (50-2000 Pa/m) using two different supply and return temperature modes (high and low). Then an optimisation model was developed using the FICOTM Xpress optimisation tool. Optimal operation of district heating design cases over a year was carried out to minimise annual total energy/exergy consumption at steady state condition. The district heating design cases with minimum optimal annual total energy/exergy consumption were determined and district heating pipe diameters were found.