Improved calculation method of age distribution of supply air inside room with HVAC system with returning air: Theory and measurement example

摘要

The local mean age of air is well known and widely used as one of the important parameters in assessing ventilation effectiveness and air distribution phenomena1,2). The age of air was defined as the time required for supply air to reach an arbitrary point in a space from supply inlet. Since, there are multiple paths from an inlet to a point, local mean age, the average time for air to travel from an inlet to any point, is widely used. Actually, some experiments have been conducted to make evaluation of air-conditioning system by means of local mean age of air3,4). This paper presents the improved calculation method of age distribution of supply air inside room with HVAC system with returning air. The measurements were performed using the improved tracer gas step-up method.