Auxiliary dual-mode rotating cylinders for energy-efficient thermal management in prosumer buildings: A coupled TRNSYS–CFD investigation

The transition toward energy-efficient prosumer buildings requires thermal management systems capable of adapting to rapidly changing seasonal loads while coordination with district heating and cooling networks. Active Heat Transfer Enhancement (AHTE) devices, such as auxiliary rotating cylinders that are integrated into the building's thermal exchange loop, offer such adaptability by providing controllable modulation of heat transfer when primary systems are insufficient. Yet, evaluating their real-world potential has been constrained by a long-standing modeling gap: CFD is needed to resolve local flow behavior within the auxiliary unit, whereas annual performance demands whole-building simulation. No existing method reliably combines these scales for prosumer-building applications. To address this challenge, this study develops a TRNSYS–CFD co-simulation framework to assess a dual-mode rotating-cylinder AHTE system serving a multi-purpose prosumer building in Ilam, Iran. The integrated model demonstrates how the controller can adjust operating conditions to navigate distinct seasonal thermofluid regimes. In winter, effective operation requires coordinated tuning of Reynolds and Rayleigh numbers to maintain strong thermal exchange and prevent buoyancy-driven performance loss. In summer, the system naturally operates in a low-Rayleigh regime, and optimal performance is achieved by regulating Reynolds-based forced convection alone. These operational patterns emerge only through the coupled framework and form the basis for a season-adaptive control strategy that enhances net energy performance. Validation against TRNSYS-CFD data indicates that incorporating the auxiliary rotating cylinder unit reduces cooling and heating loads by 3.1 % and 6.9 %, respectively. This improvement results in an overall 3.5 % reduction in annual energy consumption and a 2.8 % decrease in CO 2 emissions. In addition, the computational cost is approximately 30 % lower than that incurred by a DesignBuilder simulation for the same building. The results demonstrate that rotating cylinder AHTE systems deliver significant thermal support when integrated into external prosumer energy pathways. Moreover, the TRNSYS–CFD co-simulation framework provides a robust and scalable platform for optimizing their operation within next-generation district energy networks. • Coupled TRNSYS–CFD framework links transient building and aerodynamic flows. • Dual-mode rotating cylinders modulate flow; cut peak cooling/heating 3.1 %/6.9 %. • System lowers operational CO 2 by 2.8 %, validating active thermal management.