A new thermal characteristics analysis method of district heating systems based on hydraulic operational parameters pre-identification

Amid escalating energy tensions and mounting environmental protection concerns, heating systems are confronting with more severe challenges. The optimization and control of heating systems usually depend on dynamic thermal models. This paper employs pressure observation data under multiple hydraulic conditions to formulate matrix equations, and achieves pipe flows identification by seeking a unique solution under the full rank condition of coefficient matrix corresponding to the equations. Further, the Laplace transform method is used to express the dynamic thermal characteristics of a single pipe. A matrix representation of the dynamic thermal characteristics within the heating system is established. The findings reveal the delay characteristic and dynamic superposition rules of heat transfer in loop heating systems. Specifically, the transfer delay time in series pipes approximates the flow time of hot water through the pipe. The transfer delay time in parallel pipes lies between the delay times of the two paths, and the peak value of dynamic heat quantity is less than the sum of the peak values corresponding to the two paths. This research introduces a new method for pipe flow identification and dynamic thermal characteristics analysis of the complex heating system, thereby improving the regulation level of heating systems.