Theoretical and experimental study of the steady time of thermal transmission in brick

The high demand for HVAC systems in buildings significantly increases fossil fuel consumption, contributing to global warming. Assessing thermal transmittance through construction materials is crucial for estimating annual energy demand and indoor thermal comfort. This study focuses on the steady-state thermal transmittance through bricks. A modified test rig using a steady-state method and guarded hot plate technique was employed to experimentally investigate the thermal behavior of bricks as the same technique that used in 2009 and mentioned below. The rig that was used to calculate the heat stability time for bricks can be used to calculate the heat transfer stability time for any solid material, even if it is composed of a mixture or layers of solid materials. Numerical methods with MATLAB and ANSYS analyzed various parameters’ effects. When using MATLAB and ANSYS simulation, the heat transfer stability time of brick was 11.46 hours, while the experimental results was 12.55 hours. The effective time constant concept determined the time required for variables to reach steady state. Results show that increasing brick length from 0.1 to 0.2 meters and temperature difference from 10°C to 100°C raises steady-state time up to 3.99 times and thermal equilibrium time by 10 times, respectively. Increasing thermal conductivity up to 50 W/m.K reduces steady-state time by about 75%. Higher heat capacity and density rates up to 300 J/kg.K and 300 kg/m³ increase steady-state time by approximately 74.9% and 78.3%, respectively.