Solar-assisted induced ventilation of small field structures

Induced passive ventilation was studied in a small field structure, about 60 cm ×30 cm ×85 cm in size, heated by solar irradiation. The structure has three stories, connected by a vertical duct, which in turn is connected to a horizontal duct above the upper level of the structure. The outer walls of these two ducts are metal sheets painted on the outside with black matte paint and covered by glass sheets. The other outer walls and inner partitions of the structure are made of cardboard attached to a metal frame. Additional elements included in some experiments were a water tank, used for heat storage, and a chimney for enhancing air flow. The structure orientation was with its vertical metal sheet facing south-west. Experimental study, based on temperature and velocity measurement, and computer simulations, using the FLUENT software, were performed. During a typical experiment, the structure has been exposed to the sun for a full day in July through November. The ports of the system were either opened in the morning, or kept closed until about 13:45-14:00 and then opened. The results of the study indicate that effective ventilation has been achieved: the calculated rates of air change inside the stories were rather high, and the mean air temperatures were only about 1-2°C above the ambient in its lower stories and 2-3°C above the ambient in the upper story. Detailed comparison of the experimental and numerical results is presented and discussed.