抄録
In order to evaluate the cooling and heating effect of underground pit as one of the Earth-to-Air Heat Exchangers for diurnal cycle, unsteady CFD simulations for the pit of an office building in summer and winter were carried out using the results of one dimensional heat conduction analysis for underground in vertical direction as initial condition. The following results were obtained: 1) Outlet air temperature, cooling and heating performance of the underground pit system were predicted approximately in this CFD analysis. 2) The contribution ratio to outlet air temperature fluctuation of bottom surface in the pit was the largest in summer and winter. Especially in summer daytime, since warm outdoor air flowed along with the upper part of the pit, the contribution ratio of bottom surface became small. In winter, contribution ratios in the pit hardly changed all day long. 3) The relative humidity in the pit of summer was high and the difference of air temperature at inlet and outlet was small from midnight to morning. During daytime, the difference became about 7.5-8.0%. The dew condensation did not occur on these analysis conditions.
