Thermal buoyancy driven flows inside the solar chimney: Volume flow and heat transfer rates effected through immersed solid obstacles with different thermal conductivity and flushly-inserted discrete heating elements

To reduce the energy consumption of buildings and enhance ventilation performance of a solar chimney, a modified solar chimney, i.e., discretely immersing solid obstacles with different widths and thermal conductivity on the central axis of the chimney across the channel gap, was proposed. The effects of morphological configuration and thermal conductivity of the solid obstacles on volume flow rate induced by the chimney and heat transfer rate are numerically investigated over a range of thermal Rayleigh(Ra) numbers. It was found that increasing Rayleigh leads to the enhancement in the overall induced air flow rate when two obstacles and one obstacle with different widths were inserted in the channel, except for the case of one thinner obstacle with width Wd = 0.04 and Wd = 0.08 at higher Ra. In general, obstacle of width Wd = 0.4 were placed at height H1 = 4 in the channel could induce the highest values of volume air flow rate, then redcued by two obstacles jointly, and the least values could be done by one obstacle located H1 = 2. Additionally, obstacle numbers and configurations have trivial effects on the convective heat transfer rate of the absorber wall, especially for Ra above 105. Thermal conductivity of solid obstacles also put effect on the chimney ventilation performance. When thermal conductivity ratio Kr varies between 10 and 100, volume flow rate does little changes with increasing Ra.When Kr = 0.1, i.e., solid obstacle is themal-insulated, volume air flow rate became smaller than those of Kr = 10 and 100.Therefore, volume air flow rate induced from indoor could be enhanced mainly depending onlifting obstacle height above the bottom and expanding its width. Discrete heat source PV of D0 = 1, S0 = 1 flushly inserted the galzing could facilitate the solar chimney to induce more air into the channel compared with the chimney without discrete heat source and those of with different S0 ones, where D0 = 1 is maintained. While the solar chimney without inner obstacles and only with discrete heat source D0 = 1, S0 = 1, maximum air flow rate could be obtained among the solar chimney with different heat sources.Overall, present work could be significant for enhancing general solar chimney ventialtion and heat removal by discretely immersing conductive solid obstacles in the channel.