Distributed thermal storage for mitigating heat supply-demand imbalance in district heating systems: A thermohydraulic analysis

Heat supply–demand imbalance in district heating systems can arise from fluctuations in renewable energy generation and temporally varying demand. This imbalance is particularly pronounced in case simultaneous users' heating regulation behavior (HRB) causes a sudden surge in heat load and substantial heat shortages. To address the imbalance issues, a distributed thermal energy storage (DTES) strategy is proposed and analyzed. First, heat supply–demand imbalance quantitative model is developed to evaluate heat shortages induced by users' HRB. Then, a thermohydraulic calculation model coupling heating networks with thermal energy storage is developed to examine how the placement of DTES affects indoor temperature, thermal state of substations and pump operating parameters. Finally, based on the established model, the effects of DTES and centralized thermal energy storage (CTES) on the thermohydraulic performance of heating networks are compared. The case study results indicate that users’ HRB can lead to a heat shortage of 49%–92%. When DTESs are deployed at far-end, indoor temperature increases by 5.17%, and the proportion of insufficient substations decreases by 33.33% compared with deploying at near-end. DTES reducing the proportion of insufficient substations by 28.57% and pump power by 14.29% than CTES yields a more favorable thermohydraulic performance.