An aerosol generator of high stability

Liu, Benjamin Y. H.; Lee, K. W.

doi:10.1080/0002889758507357

Cited by 210 publications

(65 citation statements)

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“…1c. Polydisperse ammonium sulfate particles were generated by atomizing a 0.01 M aqueous solution with a constant rate atomizer (Liu and Lee, 1975). The atomized particles were immediately dried by a silica gel diffusion drier.…”

Section: Experimental Testingmentioning

confidence: 99%

The Caltech Photooxidation Flow Tube reactor: design, fluid dynamics and characterization

et al. 2017

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Abstract. Flow tube reactors are widely employed to study gas-phase atmospheric chemistry and secondary organic aerosol (SOA) formation. The development of a new laminar-flow tube reactor, the Caltech Photooxidation Flow Tube (CPOT), intended for the study of gas-phase atmospheric chemistry and SOA formation, is reported here. The present work addresses the reactor design based on fluid dynamical characterization and the fundamental behavior of vapor molecules and particles in the reactor. The design of the inlet to the reactor, based on computational fluid dynamics (CFD) simulations, comprises a static mixer and a conical diffuser to facilitate development of a characteristic laminar flow profile. To assess the extent to which the actual performance adheres to the theoretical CFD model, residence time distribution (RTD) experiments are reported with vapor molecules (O 3 ) and submicrometer ammonium sulfate particles. As confirmed by the CFD prediction, the presence of a slight deviation from strictly isothermal conditions leads to secondary flows in the reactor that produce deviations from the ideal parabolic laminar flow. The characterization experiments, in conjunction with theory, provide a basis for interpretation of atmospheric chemistry and SOA studies to follow. A 1-D photochemical model within an axially dispersed plug flow reactor (AD-PFR) framework is formulated to evaluate the oxidation level in the reactor. The simulation indicates that the OH concentration is uniform along the reactor, and an OH exposure (OH exp ) ranging from ∼ 10 9 to ∼ 10 12 molecules cm −3 s can be achieved from photolysis of H 2 O 2 . A method to calculate OH exp with a consideration for the axial dispersion in the present photochemical system is developed.

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Section: Experimental Testingmentioning

confidence: 99%

The Caltech Photooxidation Flow Tube reactor: design, fluid dynamics and characterization

et al. 2017

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“…1b, an aerosol was atomized from the aqueous solutions of pure compounds in distilled water (2-6 g L −1 ) using a custombuilt Collison-type atomizer (Liu and Lee, 1975) with dry nitrogen flow. The atomizer output was diluted with dry, particle-free nitrogen, and dried with a silica gel diffusion dryer, which reduced the relative humidity to less than 10 %.…”

Section: Aerosol Generation and Measurementmentioning

confidence: 99%

Broadband measurements of aerosol extinction in the ultraviolet spectral region

et al. 2013

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Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross sections and complex refractive indices. We describe a new laboratory instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360–390 and 385–420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We determined aerosol extinction cross sections and directly observed Mie scattering resonances for aerosols that are purely scattering (polystyrene latex spheres and ammonium sulfate), slightly absorbing (Suwannee River fulvic acid), and strongly absorbing (nigrosin dye). We describe an approach for retrieving refractive indices as a function of wavelength from the measured extinction cross sections over the 360–420 nm wavelength region. The retrieved refractive indices for PSL and ammonium sulfate agree within uncertainty with the literature values for this spectral region. The refractive index determined for nigrosin is 1.78 (± 0.03) + 0.19 (± 0.08)i at 360 nm and 1.63 (± 0.03) + 0.21 (± 0.05)i at 420 nm. The refractive index determined for Suwannee River fulvic acid is 1.71 (± 0.02) + 0.07 (± 0.06)i at 360 nm and 1.66 (± 0.02) + 0.06 (± 0.04)i at 420 nm. These laboratory results support the potential for a field instrument capable of determining ambient aerosol optical extinction, average aerosol extinction cross section, and complex refractive index as a function of wavelength

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“…alumina and Arizona road dust) dispersed in powder form by a fluidized bed aerosol generator (TSI Inc., St. Paul, model 3400), and solid and liquid particles generated by atomization of liquid solutions (KCI, NaCl and DOS). For the generation of DOS in isopropyl alcohol, a condensation aerosol generator (Liu and Lee, 1975) was used for high output stability.…”

Section: Introductionmentioning

confidence: 99%

Particle Charge Distribution Measurement for Commonly Generated Laboratory Aerosols

Forsyth

Liu

Romay

1998

Aerosol Science and Technology

Self Cite

105

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ABSTRACT. An improved particle charge analyzer system has been developed to measure the absolute charge distribution of common generated laboratory aerosols. The charge analyzer system consists of an integral cylindrical mobility analyzer used in conjunction with an optical aerosol spectrometer, with computer assisted operation and data reduction. The charge analyzer collects aerosol particles over an absolute electrical mobility range from 4.2:1:10-~ to 400 cm2/(stat -Volt second) and flow rates that can vary from 0.3 to 30 liters per minute. The charge analyzer has been used to investigate the nature of spray and contact electrification during aerosol generation by measuring the residual charge distribution on the liquid and solid generated particles. In addition, the neutralization of charged particles by bipolar ions also was studied using conventional neutralizers that use ionizing radiation from alpha and beta sources. Charge distribution measurements were performed on alumina dust (Al), Arizona road dust (ARD), potassium chloride (KCI), sodium chloride (NaCl) and di-octyl sebacate (DOS) liquid particles. Aerosol generation devices include a Collison atomizer, a condensation aerosol generator and a fluidized bed dust generator. Our work provides experimental charge distribution data for comparison with simple models of electrification theory. Experimental results showed that charge levels of atomized KC1 and NaCl particles were high and decreased as the dissolved ion concentration increased. DOS particles generated by evaporation-condensation were both neutral and moderately charged. These conclusions support the existence of a dipole layer at the liquid-gas interface that interacts with dissolved particles and changes their charge state. Alumina and ARD generated by the fluidized bed disperser are highly charged due to strong contact electrification during dispersion. In most cases, the charge on generated aerosols could be reduced to Boltzmann charge equilibrium conditions by commonly used radioactive neutralizers.

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An aerosol generator of high stability

Cited by 210 publications

References 0 publications

The Caltech Photooxidation Flow Tube reactor: design, fluid dynamics and characterization

The Caltech Photooxidation Flow Tube reactor: design, fluid dynamics and characterization

Broadband measurements of aerosol extinction in the ultraviolet spectral region

Particle Charge Distribution Measurement for Commonly Generated Laboratory Aerosols

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