Effect of room air recirculation delay on the decay rate of tracer gas

Effect of room air recirculation delay on the decay rate of tracer gas

TitleEffect of room air recirculation delay on the decay rate of tracer gas
Publication TypeConference Proceedings
Year of Publication2004
AuthorsAstrid H. Kristoffersen, Ashok J. Gadgil, David M. Lorenzetti
Conference Name9th International Conference on Air Distribution in Rooms - RoomVent 2004,
Paginationpp 6
Date PublishedSeptember 5-8, 2
Conference LocationCoimbra, Portugal
Abstract

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.