Transient heat flow simulations for assessing the performance of radiant panel installations under concrete building floors

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University of New Brunswick


Three models are developed to study the long-term thermal performance of a radiant heat floor system with sub-grade thermal storage. An existing steady-state 1D model of the system is verified using a quasi-1D CFD-CHT model. A full-scale parametric study is performed using a Simulink-based model representing a central vertical section of a typical industrial installation, including conjugate heat transfer at the floor surface. The transient conjugate heat transfer modelling capability of the EXN/Aero CFD suite is verified. A prescribed set of CFD-CHT simulations using EXN/Aero is developed, tested, and proposed to further study the systems performance. These simulations include conjugate heat transfer at solid-fluid interfaces, radiation field and natural convection modelling coupled with the energy equation in the heated space, and an embedded temperature-controlled heating element, all of which have been tested and verified. Results confirmed the hypothesis that insulation installed between the heating panel and the concrete slab is severely detrimental to the system’s performance, while insulation installed below the heating panel is somewhat beneficial. Recommendations regarding sub-grade insulation for the system and further studies are provided based on Simulink and EXN/Aero simulation results.