Optimization of hydraulic distribution using loop adjustment method in meshed district heating system with multiple heat sources

With the development of urbanization, the scale of the district heating system (DHS) has increased significantly, and the meshed DHS with multiple heat sources has become a popular trend due to its safety for providing heating. However, the current dispatch strategy of the DHS only focuses on regulating supply temperatures or flow rates in each heat source and ignores the loop adjustment, which leads to a waste of energy. The loop adjustment method is proposed by installing valves or pumps in the loop pipelines, which can improve hydraulic distribution of the DHS and reduce energy consumption of the total pumps. Since the DHS with loop adjustment method is a nonlinear optimization problem, an improved algorithm which combines the particle swarm optimization and the linear search method is used to solve this problem. The best installation positions of the loop valves or pumps are obtained, as well as their corresponding working conditions. Then, the hydraulic performance under three modes (without loop adjustment strategy, with loop valve strategy and with loop pump strategy) is compared in an actual DHS, and results show that the total pump power can be reduced by more than 20.3% and 29.5% after adopting the loop adjustment method.