Fatigue data acquisition, evaluation and optimization of district heating pipes

District heating (DH) transmission piping, composed of supply and return pipes, has been used to transmit heat efficiently without heat loss. This research aims to systematize the data processing of transition temperature, evaluate the temperature effects on pipe fatigue life, and optimize the size of DH pipes. For this purpose, a total of about 5 million temperature data were measured for 1 year at 10 locations. Then, available fatigue life estimation schemes were examined and applied to quantify the specific thermal fatigue life of each pipe. With regard to Korean DH pipes, a relational database management system as well as reliable fatigue life evaluation procedures was established. As prototypal optimization analysis results, the mean value of the original cross-sectional areas of the selected pipes was reduced by 18.6% while sufficient margins against fatigue failure was maintained. Therefore, the optimization analysis results can be used as useful information for setting a suitable operating condition and stabilizing the water temperature for design, operation and energy saving of DH heating piping in the future.