Oxygen enrichment characteristics of an enclosed architectural space under anoxic conditions

A set of experimental devices for the measurement of indoor oxygen supply in an enclosed architectural space was built. The devices were used to analyze the effects of the number and diameter of oxygen-feeding ports, oxygen flow rate, and oxygen-feeding mode on the indoor oxygen enrichment characteristics and efficiency of an architectural space. Results show that the distribution of the maximum axial oxygen concentration tends to decline with axial distance under different numbers and diameters of oxygen-feeding ports, oxygen flow rates, and oxygen-feeding modes. Axial oxygen concentration rapidly decreases when the axial distance to the oxygen-feeding port ranges from 0 m to 0.55. In general, the oxygen-enriched region that forms in a single oxygen-feeding port under different pipe diameters and oxygen flow rates presents a flat elliptical shape. The oxygen-enriched area expands under a constant oxygen-feeding pipe diameter and an increasing oxygen flow rate. The oxygen-enriched area that forms in double oxygen-feeding ports, wherein one is positioned vertically forward and the other port is positioned 45° opposite the forward-facing port, has a bifurcated shape with one pointed head and one rounded head. The oxygen-enriched area that forms in the vertical forward-facing port is larger than that in the 45° opposing port. Under back-to-back oxygen feeding, the oxygen-enriched area that forms in double oxygen-feeding ports with the pipe diameter of 6 mm generally exhibits a two-bladed fan shape, whereas that in double oxygen-feeding ports with the pipe diameter of 10 mm appears as two overlapping semicircles. Under the total oxygen delivery flow rate of 1 m³·h^-1, the range of oxygen feeding in double oxygen-feeding ports with the pipe diameter of 6 mm and 45° angle is the largest and that in double oxygen-feeding ports with the pipe diameter of 10 mm and vertical forward position is the smallest. Under a constant total oxygen flow rate and oxygen-feeding mode, the oxygen-enriched area that forms in the single oxygen-feeding port in the vertical forward position is 20% larger than that in the double oxygen-feeding ports in the vertical forward position. Under the same number of oxygen-feeding port, oxygen flow rate, and oxygen-feeding mode, the oxygen-enriched area in the oxygen-feeding port with the pipe diameter of 6 mm is approximately 60% larger than that in the oxygen-feeding port with the pipe diameter of 10 mm.