Evaluation of heat transfer performance of engineered wood flooring with built-in electric heating semi-conductive layer

  Objective  This study aimed to provide a theoretical basis for the optimal design of the electrothermal flooring. On the basis of ensuring physical and mechanical properties, the influence of material composition and floor structure on the electric heating performance of the semiconductor heating multi-layer engineered wood flooring was explored.

  Method  Four distinct structural schemes of the electrothermal floor were constructed using wood species optimization, orthogonal compounding, and structural symmetry with the cross-sectional density of the floor as the central focus of the structure-function connection. The electrothermal performance and energy consumption were compared and assessed by examining the impact of floor section density on the effect of heat transmission.

  Result  In order to ensure the heat transfer efficiency, the semiconductor electric heating layer should be placed between the substrate and the surface layer, and the power density was suggested to be set within the range of 200–300 W/m². After comprehensive evaluation of the heat transfer efficiency, thermal insulation performance and energy consumption of the electrothermal floor, C-structure with mixed tree species was the optimal structure, in which the symmetrical structure of two layers of birch was chosen as the surface layer and three layers of eucalyptus in the core layer. When the power density of C-structure electrothermal floor was set to300 W/m², the maximum surface temperature reached 47.3 ℃, the electric-thermal radiation conversion efficiency was 76.7%, and the average temperature amplitude of natural cooling-down was 29.3%. The electricity consumed to reach the target temperature of 45.4 ℃ was 1 877.4 × 10⁻³ kW·h.

  Conclusion  The density of floor cross section varies with different wood types and structures, which has a significant effect on thermal conductivity, heat transfer process and electrothermal performance. In the preparation of electrothermal floor substrate, the wood with high density, high thermal conductivity and high strength is suggested to use as the outer layer, and the wood with low density, low thermal conductivity, and low strength to use as the core layer. On the basis of assuring physical and mechanical features including dimensional stability, the “sandwich” structure formed by the electrothermal fool may significantly increase electrothermal performance and energy consumption.