Modeling and Optimization of a Northern China District Heating System: A Dymola-Based Study

With the continuous development of intelligent heating technology, while the district heating system achieves clean and efficient operation, it also faces the practical challenges of uneven hydraulic distribution and energy waste. In order to improve the efficiency of heat energy transmission and distribution, this paper takes a typical northern residential community as a case, constructs a nonlinear hydraulic model of the secondary heating system based on the Modelica language, and integrates an interior - point optimization solver to realize the joint regulation of pump frequency and valve opening. Aiming at the heat load fluctuations at different time scales, two dynamic regulation strategies, namely the hourly - level and daily - level strategies, are designed, and the system operation data are simulated and analyzed. The results show that compared with the daily - level strategy, the hourly - level optimization is more flexible in responding to heat load changes. It not only significantly improves the system hydraulic balance, but also reduces the energy consumption of the circulating water pump by 36.61% and the total water supply flow by 21.36%. This study proves the feasibility and high efficiency of the hydraulic regulation method based on nonlinear optimization in the district heating system, and provides a replicable engineering path for intelligent regulation and energy - saving operation.