Effect of the solar roof chimney position on heat transfer in a room

Abstract

This study reports a numerical-experimental analysis of heat transfer and airflow in a scaled room with a heated wall coupled with a double-channel vertical roof solar chimney. For the experimental study, a parametric study was performed in the thermal system, considering different values of heat flux supplied to a vertical wall of the scaled room and six different positions of the roof solar chimney. Experimental temperature profiles were obtained at six different depths and heights and experimental heat transfer coefficients were computed for both heated surfaces. The renormalization group k-ε turbulence model was evaluated against experimental data using computational fluid dynamics software. With the validated model, the effect of heat sources on temperature fields, flow patterns, and heat transfer convective coefficients is presented and discussed. The case with heat flux on the heated wall produces the biggest amount of air changes per hour, being the nearest position of the solar chimney to the air inlet the case with more air removal with 30.24 air changes per hour, corresponding to an output velocity of 0.13 m/s, compared to lower performance setting with 0.06 m/s muzzle velocity, likewise, this configuration presented the best thermal behavior for the configurations with and without the heated wall, with temperatures oscillating between 298 to 301 K. For this reason, it is important to consider this numerical-experimental (3D) study, to obtain the best use of natural ventilation and air changes per hour, offered by a double-channel roof solar chimney, being an efficient, economic, and ecological way of maintaining natural ventilation in buildings to live or work.