Abstract
Ventilating performance of various duct systems were examined by the model experiment in the laboratory, the field test in the real apartment house and a theoretical computer simulation. The types of the duct system are as follows. I-type means the duct system which has two horizontal ducts passing through the apartment unit from one exterior wall to another exterior wall, one for intaking the outdoor fresh air, the other for exhausting the indoor polluted air. The outdoor fresh air is intaken by the short vertical duct branched off at the middle of the horizontal duct which passes through the apartment unit. On the other hand, the indoor polluted air is exhausted by the fan and the duct branched off at the middle of the other horizontal duct. T-type means the duct system which has only one horizontal duct passing through the unit for exhausting the indoor air. L-type duct system has one horizontal duct which doesn't pass through the unit but passes through only one side exterior wall for exhausting the indoor air. LL-type duct system has two horizontal ducts passing through the one side exterior wall, one for intaking the outdoor air, another for exhausting the indoor air. The results of the experiments are as follows. (1) I-type duct system is the best one which intakes stably the outdoor fresh air and exhausts stably the indoor air, varing no influenced by the outdoor wind force. (2) T-type is also stable system, if the duct system is equipped in the apartment which is not so air tight. In this case, the outdoor air may be able to come in through the gaps of windows and exteriors. But, if the apartment is air tight enough, it is necessary to install the ventilating air inlet on the exterior wall. (3) L-type duct system doesn't exhaust the indoor air stably when the wind blows onto the wall through which the horizontal duct passes for exhausting the indoor air. If the pressure force of the fan is not superior to the wind pressure, the reverse air flow may occur. (4) LL-type system has the same defect as the L-type system, unless the apartment is perfectly air tight. (5) The diameter of the horizontal duct should be larger than 15cm in the case of I-type and T-type system. The grill at the top of the horizontal duct and the the grease filter at the kitchen hood should be sellected so as to have small pressure loss.
