Natural ventilation performance of solar chimney with and without earth-air heat exchanger during transition seasons

Abstract

This study experimentally investigates the natural ventilation performance of a solar chimney (SC) integrated with an earth-air heat exchanger (EAHE) during the transition seasons. The experiment was conducted in a comparative manner under three operating modes: Mode A: SC operating with EAHE with the window closed; Mode B: SC operating with an open window with the same opening area as the cross-sectional area of the EAHE pipe, with the EAHE closed; Mode C: the operating mechanism was the same as that of Mode B with the window opening area doubled. The results showed that 24 h of natural ventilation was achieved for the three operating modes. However, the nocturnal ventilation driving force for Mode A was the heating effect of the subsoil, while that for Modes B and C was the heat released from the thermal mass. The average daytime and nocturnal airflow rates for Modes A, B, and C were 209 m3/h and 139 m3/h, 286 m3/h and 87 m3/h, and 340 m3/h and 80 m3/h, respectively. The 24 h overall heating and cooling capacities of the EAHE for Mode A were 19474 kJ and 2179 kJ, respectively. The SCEAHE system had an advantage in preserving acceptable indoor thermal comfort with a diurnal indoor temperature variation in the range 19.7–22.7 °C.