Tracer gas measurements are commonly used to estimate the fresh air exchange rate in a room or building. Published tracer decay methods account for fresh air supply, infiltration, and leaks in ductwork. However, the time delay associated with a ventilation system recirculating tracer back to the room also affects the decay rate. We present an analytical study of tracer gas decay in a well-mixed, mechanically-ventilated room with recirculation. The analysis shows that failing to account for delays can lead to under- or over-estimates of the fresh air supply, depending on whether the decay rate calculation includes the duct volume.
Effect of room air recirculation delay on the decay rate of tracer gas concentration
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Year:
2004
Bibliographic info:
RoomVent 2004, 9th international conference in University of Coimbra - Portugal, 5-8th september 2004, pp 6, 3 Fig., 5 Ref