Utilization of cool ceiling with roof solar chimney in Thailand: The experimental and numerical analysis

The objective of this paper is to study the benefits of application of solar chimney on the south roof and cool metal ceiling on the north roof through the experiment in a detached building called a controlled cell, and the related numerical model constructed from a computational fluid dynamics (CFD) program. The experimental results are used for calculation of values of heat transfer coefficient of the cool ceiling and evaluation of the mean cooling potential of the combined passive cooling system. The two-dimensional numerical models generated by the CFD program use the mean values of wall temperatures in the application of solar chimney in the controlled cell as the boundary conditions. The effects of cool ceiling on the temperature, velocity and airflow rate in the controlled cell are investigated through the numerical model in which the north ceiling temperature is reduced by 2–4°C from the measured value of 32.8°C. The mean cooling potential of the application of combined system is found to be two times higher than the application of the solar chimney. Good agreements between the predicted and experimental results are obtained from the comparison of temperature and volume flow rate at the middle section of the controlled cell. The reduction of north ceiling temperature in the free-convection numerical model shows the decrease of air temperature in the upper region of the room by 0.5–0.7°C from the original value of 33.3°C, and the increase of volume flow rate by 12%.