Gas collection efficiency of annular denuders: A spreadsheet-based calculator

Denuders are widely used for atmospheric analysis. Annular denuders are especially well-suited for preconcentration of trace gases compared to simpler single tube designs. While traditionally coated annular denuders have both bounding surfaces that behave as sinks, annular denuders/membrane-based scrubbers with the same basic geometric design and with only one of the annular surfaces functioning as sink (e.g., a membrane tube whose outer surface behaves as a sink disposed within an inert jacket tube) have become common. However, the gas collection efficiency of such devices cannot be expressed as a simple equation with fixed constants and there is no presently available tool to a priori determine the denuder performance or to design denuders with specific removal efficiencies at specific sampling rates. This paper presents a simple to use " spreadsheet calculator" for concentric annular denuders of any dimension based on known solutions to analogous heat transfer problems. The results from the present spreadsheet calculator are compared with results from a commercial computational fluid dynamics package (. Fluent™; this takes significant expertise and development effort to run)-the two approaches produce essentially the same results. The present spreadsheet calculator can be used easily and simply without training and will be a useful tool for denuder users and designers.