Investigation of thermal-hydraulic coupling impact on transient modeling of steam flow in integrated energy systems

Transient modeling is essential for characterizing multi-energy flow dynamics in integrated energy systems, yet typically relies on the thermal-hydraulic decoupling assumption to ensure computational efficiency. This study develops a steam transient analytical model (STAM) to systematically evaluate the applicability boundaries of thermal-hydraulic decoupling. Through statistical analysis of actual industrial steam data, this study compares coupled numerical simulations against decoupled STAM solutions across diverse steam temperature fluctuations. Case#1 examines a single pipeline under 16 operational scenarios, quantifying decoupling applicability ranges via error curve fitting and revealing dominant error sources. Case#2 further validates the decoupling assumption under actual parameter fluctuations through a 24-node steam network. Key findings demonstrate: (1)The dominant steam parameter contributing to STAM errors varies under different baseline pressures; (2) Although thermal-hydraulic decoupling becomes invalid in low-pressure pipelines experiencing sudden pressure changes, it remains applicable under all other conditions at an average amplitude threshold of 11.66 % for temperature fluctuations; (3) Parameter fluctuations in operational energy systems exhibit irregular yet bounded characteristics, and the thermal-hydraulic decoupling assumption in STAM demonstrates applicability in the investigated steam network case study. This research provides critical references for the deployment of transient modeling in various scenarios.