Effect of Absorbent Geometry Variation on Thermal Performance in Trombe Wall Systems

Abstract This study investigates the thermal performance of Trombe walls as passive solar energy systems through experimental analysis. The traditional absorber plate was modified to create next-generation solar wall modules with three different surface geometries: flat, trapezoidal, and sinusoidal. Experiments were conducted in a Mediterranean climate zone (37 deg N, Csa) using 17 measurement points to collect key thermal data, including heat flux (Q, W/m2), air velocity (v, m/s), and temperature difference (ΔT, °C). Results showed that the sinusoidal panel had the highest performance, reaching a maximum heat flux of 161 W/m2 and an air velocity of 0.4178 m/s. The trapezoidal panel followed with 157 W/m2 and 0.3269 m/s, while the flat panel showed the lowest values at 141 W/m2 and 0.2847 m/s. Empirical equations were developed to predict heat flux, airflow, temperature difference, and efficiency based on the solar irradiance and panel geometry. Statistical analysis confirmed the reliability of these models with the determination coefficient (R2) between 0.75 and 0.98, the root mean square error between 0.01 and 18.90, and the sum of squared error from 0.001 to 6788. Findings highlight the importance of absorber surface geometry in enhancing passive solar gains. Among the tested designs, the sinusoidal surface significantly improved heat transfer and energy efficiency. This research supports the optimization of Trombe walls for sustainable building design, promoting more effective use of renewable energy and passive heating strategies.