Atmospheric Measurement Techniques www.atmos-meas-tech.net 1867-1381 1867-8548 2 2 2009 10.5194/amt-2-417-2009 http://www.atmos-meas-tech.net/2/417/2009/ http://www.atmos-meas-tech.net/2/417/2009/amt-2-417-2009.html http://www.atmos-meas-tech.net/2/417/2009/amt-2-417-2009.pdf 417 422 2009-07-30 Design and performance of an automatic regenerating adsorption aerosol dryer for continuous operation at monitoring sites T. M. Tuch tuch@tropos.de A. Haudek T. Müller A. Nowak H. Wex A. Wiedensohler Leibniz Institute for Tropospheric Research, Leipzig, Germany Sizes of aerosol particles depend on the relative humidity of their carrier gas. Most monitoring networks require therefore that the aerosol is dried to a relative humidity below 50% r.H. to ensure comparability of measurements at different sites. Commercially available aerosol dryers are often not suitable for this purpose at remote monitoring sites. Adsorption dryers need to be regenerated frequently and maintenance-free single column Nafion dryers are not designed for high aerosol flow rates. We therefore developed an automatic regenerating adsorption aerosol dryer with a design flow rate of 1 m³/h. Particle transmission efficiency of this dryer has been determined during a 3 week experiment. The lower 50% cut-off was found to be smaller than 3 nm at the design flow rate of the instrument. Measured transmission efficiencies are in good agreement with theoretical calculations. One dryer has been successfully deployed in the Amazon river basin. We present data from this monitoring site for the first 6 months of measurements (February 2008–August 2008). Apart from one unscheduled service, this dryer did not require any maintenance during this time period. The average relative humidity of the dried aerosol was 27.1+/−7.5% r.H. compared to an average ambient relative humidity of nearly 80% and temperatures around 30°C. This initial deployment demonstrated that these dryers are well suitable for continuous operation at remote monitoring sites under adverse ambient conditions. Baltensperger, U., Barrie, L., Fröhlich, C., Gras, J., Jäger, H., Jennings, S. G., Li, S. M., Ogren, J., Wiedensohler, A., Wehrli, C., and Wilson, J.: WMO/GAW aerosol measurement procedures, guidelines and recommendations. World Meteorological Organization Global Atmosphere Watch No 153 (September 2003) WMO TD No 1178, 2003. Baron, P. A. and Willeke, K.: Aerosol Measurement, 2nd Edition, J Wiley and Sons, 170–178, 2001. Bergin, M. H., Ogren, K. O., Schwartz, S., and McInnes. L.: Evaporation of Ammonium Nitrate Aerosol in a Heated Nephelometer: Implications for Field Measurements Environ. Sci. Technol, 31, 2878–2883, 1997. Birmili W., Stratmann, F., and Wiedensohler, A.: Design of a DMA-based size spectrometer for a large particle size range and stable operation, J. Aerosol Sci., 30, 549–553, 1999. Charron, A., Harrison, R.M., Moorcroft, S., and Booker, J.: Potential for simultaneous measurement of PM$_10$, PM$_2.5$ and PM$_1$ for air quality monitoring purposes using a single TEOM, Atmos. Environ., 38, 21, 3453–3458, 2004. Cyrys, J., Dietrich, G., Kreyling, W., Tuch, T., and Heinrich, J.: PM$_2.5$ measurements in ambient aerosol: comparison between Harvard impactor (HI) and the tapered element oscillating microbalance (TEOM) system, Sci. Tot. Environ., 278(1–3), 191–197, 2001. Mozurkewich, M.: Aerosol Growth and the Condensation Coefficient for Water: A Review, Aerosol Sci. Technol., 5(2), 223–236, 1986. Ten Brink, H. M., Khlystov, A., Kos, G. A. P., Tuch, T., Roth, C., and Kreyling, W.: A high-flow humidograph for testing the water uptake by ambient aerosol, Atmos. Environ., 34(25), 4291–4300, 2001. Wex, H., Kiselev, A., Ziese, M., and Stratmann, F.: Calibration of LACIS as a CCN detector and its use in measuring activation and hygroscopic growth of atmospheric aerosol particles, Atmos. Chem. Phys., 6, 4519–4527, 2006.