Linear programming optimization of heat distribution in a district-heating system by valve adjustments and substation retrofit

The unbalanced distribution of heat in a district-heating system may be caused by the increase of hydraulic resistance of pipe network, decrease of heat transmittance of radiators inside buildings, and increase of heat transmittance of building envelope. This situation yields the overheating of some buildings and underheating of other buildings. A district-heating system is analyzed that consists of heat plant, primary pipe network, substation, secondary pipe network, and three buildings. A steady-state, bottom-up approach and the sequential linear programming is used to solve this optimization problem. Results show that significant improvement of thermal comfort may be reached by adjusting the valves of secondary pipe network and resizing of the substation heat exchanger.