Detection of sub-5nm naturally charged carbonaceous materials from a sooting laminar premixed flame by a water condensation Particle Counter (WCPC) enhanced by a Di-Ethylene Glycol (DEG) saturator inlet

Combustion is one of the major contributors to air pollution and Condensation Particle Counters (CPCs) provide effective monitoring of atmospheric aerosols since they can detect both charged and neutral materials in low number concentrations. The detection efficiency of any CPC for materials smaller than 5 nm requires ad-hoc calibrations because it is affected by the analyte's size, shape, charge state, composition, and wettability by the condensing fluid. This study characterizes a Water-based CPC (WCPC) prototype for the detection of the naturally charged carbonaceous products of an incipiently sooting laminar premixed flame. The WCPC can activate condensation growth and (50% efficient) detection of hydrophobic flame-formed carbonaceous materials naturally charged in positive and negative polarities with mobility diameters as small as 4.3 nm and 4.8 nm, respectively. The addition of a simple Di-Ethylene Glycol (DEG) saturator inlet enhances the 50% detection cutoff to mobility diameters as small as 1.8 nm or 1.6 nm for materials charged in positive or negative polarity, respectively. The coupling of the DEG saturator inlet to the WCPC creates a new DEG-WCPC instrument able to detect efficiently both hydrophobic and hydrophilic sub-5nm aerosols with a marginal increase in manufacturing cost (<10%), dimensions, and weight (<0.25 kg).

Automated summary

Combustion is a major cause of air pollution, and CPCs are effective in monitoring atmospheric aerosols. This study characterizes a water-based WCPC prototype that can detect charged carbonaceous materials produced by flames. The addition of a DEG saturator inlet enhances the detection efficiency. The coupling of the DEG saturator inlet to the WCPC creates a new DEG-WCPC instrument that can detect sub-5nm aerosols at a relatively low cost and small size.