Reliability segment design in single-source district heating networks based on valve network models

As a kind of critical infrastructure, district heating networks (DHNs) ensure people's life and productivity in cold area. Optimizing the reliability of DHNs has been an urgent topic for many scholars. In this study, we defined reliability segments to build a valve network, and established branched and looped pipeline models. We varied the number, heat load, and length of the reliability segments to study their influence on reliability. Then, we proposed reliability design rules for single-heat-source branched and single-looped DHNs. For branched DHNs, the failure effect of an upstream reliability segment is more serious than that of a downstream segment. The core of these rules is to ensure the reliability segment closer to the heat source contains more heat load and few fault components. For single-looped DHNs, the failure effect scope of each reliability segment is only itself. The core of these rules is to ensure the reliability segment that cannot easily fail contains more heat load. Both sets of design rules are to improve the DHN reliability by reducing the fault probability of reliability segments with severe failure effect. Finally, a case study of reliability segment design on a single-looped DHN proved the effectiveness of the proposed design rules.