Experimental and Theoretical Investigations of the Effect of the Calibration Aerosol Material on the Counting Efficiencies of TSI 3790 Condensation Particle Counters

The counting efficiencies of two TSI 3790 Condensation Particle Counters were investigated experimentally for graphite, Poly-(Alpha) Olefin (PAO), tetradecane (C14) and hexadecane (C16) particles at saturator-to-condenser temperature differences spanning from 5.6 to 11.3°C. The efficiencies determined with PAO, C14 and C16 particles were broadly similar, while tests with graphite particles resulted in systematically lower counting efficiencies. The differences between PAO and graphite particles were reduced at elevated temperature differences, i.e., as the saturation ratios inside the condenser increased. The possibility to predict measured counting efficiencies by heterogeneous nucleation theory was also assessed. The results for PAO, C14 and C16 were representative of perfectly wettable particles. Deviations were observed between theoretical predictions and experimental data at high counting efficiencies (>50%), where calculations become very sensitive to flow and temperature non-idealities. The experimental results for graphite particles up to circa 80% counting efficiencies could be reproduced with a contact angle of 6 to 12°, or a Tolman length of 0.025 to 0.09 nm, or a line tension of 5×10-11 N to 2.5×10 10 N, for all temperature differences examined. Numerical calculations for a range of working fluids suggested that for a given affinity of the calibration particle to the examined vapours (i.e., for a finite contact angle), the benefit from shifting to a fluid alternative to butanol is limited. Further investigations on the reduction of the material dependence should focus on the identification of working fluids exhibiting greater affinity for different particle materials (e.g., lower contact angle).

MAMAKOS Athanasios;  GIECHASKIEL Barouch;  DROSSINOS Ioannis; 

2012-11-06

TAYLOR & FRANCIS INC

JRC70191

0278-6826,   

https://publications.jrc.ec.europa.eu/repository/handle/JRC70191,   

10.1080/02786826.2012.716174,