Cascade sub-low temperature district heating networks in existing district heating systems

Existing district heating networks (DHNs) are often designed for relatively high temperatures, typically 80–120 °C supply and 40–60 return. The transformation of such high-temperature DHNs (HTDHNs) into more efficient low-temperature (LTDHN) towards the 4th generation is associated with great complexity effort. This paper discusses integration sub-LTDHNs return flow existing HTDHNs, thereby creating an energy cascade thus lowering overall system temperatures HTDHN. technical barriers drivers were analysed through literature research, expert interviews, a questionnaire. Their design was investigated, techno-economic analysis conducted several configurations in terms sub-LTDHN, various HTDHN potential connecting points. also planned residential area Nordic city. In addition, their operating dynamics resulting from different load conditions effects on sub-LTDHN. It found that, one hand, connection point its prevailing (mass temperature) key parameter to ensure that heat demand met. On other savings due lower sub-LTDHN pipeline significantly higher if use combustion technologies minimized.