Experimental study and numerical simulation of a floor heating system in a three-dimensional model: Parametric study and improvement

Abstract

In recent years, the installation of underfloor heating systems has increased considerably in many countries, due to their ability to be connected to a solar thermal collector in order to benefit from clean and renewable energy. This promising technology allows for reduced energy consumption, achieves a higher level of comfort, and ensures a more homogeneous temperature distribution than conventional heating systems. A huge loophole is detected in research works concerning the three-dimensional numerical modelling of the thermal behavior of underfloor heating by COMSOL Multiphysics software. The present study aims to reduce these knowledge gaps and to analyze the thermal behavior of the direct solar floor numerically and experimentally under the specific climatic conditions of Casablanca, Morocco. Visualize the thermal behavior of the underfloor heating system and the heating circuit as a 3D model using COMSOL Multiphysics software, based on the finite element method by investigating the influence of various design and operational parameters to select the best parameters that guarantee thermal comfort in the case of installing this heating system in traditional bathrooms.The results obtained by numerical simulation are then compared with those of the experimental measurements in order to verify the validity of the numerical model. The average deviation between the simulated and measured surface temperatures is approximately 1.04%, while the deviation in pipe temperature is around 3.13%, which shows a very good agreement between the numerical and experimental results. In addition, the results of the parametric study indicate that the key elements for enhancing the floor heating system are primarily a floor covered by tile with a minimum thickness of 5 mm, a pipe spacing of approximately 15 cm, a PER pipe diameter of 16/20 mm, and a thermal insulation layer with a thickness of 50 mm made of XPS or polystyrene. The incorporation of these improvements in the standard model ensures a surface temperature within the thermal comfort range of a less warm bathroom, approximately 34.13 °C, and a high heat flux emitted at the surface around 502.07 W compared to the standard model. In the literature, it was found that the comparison of architectural characteristics of direct solar floors receives minimal attention, with most studies only comparing systems in terms of thermal comfort or energy efficiency. In this study, the analysis and interpretation of the results obtained can be used to help engineers and designers select the type and dimensions of the best materials for heating floors installed in traditional bathrooms in Morocco.