Design of tubular flow reactors for monodisperse aerosol production

Abstract

Design equations are derived for calculating the properties of an aerosol generated in a tubular flow reactor operated at a constant rate of formation of condensable monomer. These equations lead to a set of characteristic dimensionless groups. Independently, it is shown that nearly monodisperse aerosols can be generated by: (1) separating particle formation and growth processes, (2) operating with a narrow residence time distribution, and (3) minimizing monomer concentration gradients. These criteria can be used in solving the design equations over ranges of the dimensionless groups suitable for monodisperse aerosol production. In general, high rates of monomer formation are desirable, subject to the desired particle size and concentration, but an upper bound may result from coagulation.

Narrowing the size distribution of aerosol-made titania by surface growth and coagulation

“…It is well known that aerosol size distributions can be narrowed by introducing seeds (Pratsinis, Kodas, Dudukovic, & Friedlander, 1986;Okuyama, Ushio, Kousaka, Flagan, & Seinfeld, 1990), by stage-wise addition (preheating) of reactants (Jang & Jeong, 1995), by suppressing particle residence time distribution and monomer radial di usion (Kodas & Friedlander, 1988), and even by using charges (Xiong, Pratsinis, & Mastrangelo, 1992;Kim & Kim, 2002). However, little attention has been paid upon the potential of reactions on the surface of particles (surface growth) to contribute to synthesis of particles with narrower size distributions than the self-preserving one.…”

Particle Size Distributions following Condensational Growth in Continuous Flow Aerosol Reactors as Derived from Residence Time Distributions: Theoretical Development and Application to Secondary Organic Aerosol

“…For this reason, the number-diameter distribution n(d) of the particle population in the reactor outflow is tightly coupled to the probability density function p(t) of particle residence time t (Dragoescu and Friedlander 1989). For instance, a tightly distributed p(t) is recommended for the production of monodisperse particles in continuous flow reactors (Pratsinis et al 1986; Kodas and Friedlander 1988). The distribution p(t) can be calculated for ideal reactors or alternatively measured for real reactors (Davis and Davis 2003), including aerosol particle reactors (Lambe et al 2011).…”

“…These approaches have considered in various ways the processes of nucleation, coagulation, and condensational growth of the particles. The approaches have included both analytical (Crump and Seinfeld 1980;Seinfeld et al 2003) and numerical (Kodas and Friedlander 1988;Verheggen and Mozurkewich 2006;Vesterinen et al 2011) solutions to the General Dynamic Equation (Friedlander 2000). Modal aerosol dynamics models have also been developed (Whitby and McMurry 1997).…”

Effectiveness of Low-Pressure Metal–Organic Chemical Vapor Deposition Coatings on Metal Surfaces for the Mitigation of Fouling from Heated Jet Fuel

“…Expansion of a gas containing a condensable vapor like aluminum secondary butoxide through a subsonic nozzle in a high pressure system was shown to produce condensate particles whose size distribution depends on the process parameters like velocity of the fluid, reservoir temperature, pressure, and saturation ratio. 30 The formation of spherulitic deposits has also been observed during the deposition of alumina from aluminum acetylacetonate in a previous study and has been attributed to the condensation of vapors into clusters during the expansion of a precursor-laden gas through a needle valve. 31 The system used in this study for the deposition of metal oxide films does not contain a needle valve.…”

“…To see whether there is a possibility of maintaining a self-cleaning surface by oxidizing the incipient carbonaceous deposits formed from thermal stressing of Jet-A by oxygen spillover, platinum was deposited on AISI 304 from platinum acetylacetonate under the conditions given in Table . It is known that the oxidation of platinum acetylacetonate at 500 °C with UHP oxygen results in the deposition of pure platinum without residual carbon contamination from the precursor. , A high resolution scan for platinum 4f at a binding energy of 71.9 eV suggests that it is present in the metallic form. The morphology of carbonaceous deposits obtained after the thermal stressing of the platinum coating, the TPO profile of carbonaceous deposits, the EDX spectrum of platinum coating after thermal stressing and the EDX elemental map of platinum, carbon, and sulfur are shown, respectively, in Figure panels a, b, c, d, and e. The morphology of solid carbonaceous deposits is similar to that obtained with all other coated surfaces.…”