Underfloor Heating System CFD Simulation

CFD Analysis of Underfloor Heating System for Indoor Thermal Comfort

Thermal regulation in buildings represents a critical challenge in mechanical engineering, particularly within the air conditioning discipline. The significant energy costs associated with maintaining comfortable indoor environments necessitate optimized HVAC system designs that balance installation expenses, operational efficiency, and performance requirements. Computational simulation offers valuable insights for identifying optimal ventilation solutions tailored to specific architectural configurations.

This project employs ANSYS Fluent to model and analyze thermal dynamics in an enclosed space heated via an underfloor system. The simulation focuses on natural convection heat transfer phenomena initiated by a constant heat flux (180 W/m²) applied to the floor surface, with all other boundaries maintained as adiabatic. Unlike forced ventilation simulations, this model excludes inlet boundaries, incorporating only a pressure outlet to allow for thermal expansion effects.

The computational domain represents a standard room, constructed in ANSYS Design Modeler and discretized using an unstructured mesh comprising 124,325 elements. The simulation methodology incorporates:

- Pressure-based steady-state solver
- Realizable k-epsilon turbulence model with standard wall functions
- Activated energy equation for thermal transport
- Ideal gas model to capture temperature-dependent density variations
- Gravitational acceleration (-9.81 m/s² in Z-direction) to model buoyancy effects

Boundary conditions include a pressure outlet (0 Pa gauge) with specified turbulence parameters and ambient temperature (300K). The solution approach utilizes a coupled pressure-velocity scheme with predominantly second-order discretization methods for enhanced accuracy.

The analysis provides comprehensive visualization of the thermal stratification patterns, pressure distributions, and natural convection flow structures within the space. Both three-dimensional and planar contour representations illustrate the complex interaction between the heated floor surface and resulting air circulation patterns, offering valuable insights for optimizing underfloor heating system design and placement for maximum thermal comfort efficiency.