Deposition rates from polydispersed particle populations of arbitrary spread

Abstract

For particle deposition from log-normal polydispersed aerosol streams by one or more of several mechanisms described by piecewise-power-law mass transfer coefficients, w e derive useful relations between actual total mass deposition rates and t h e 'reference' rate one would calculate by imagining that all particles in t h e mainstream population had t h e average particle volume V (=&/N,,). Included here are diffusion or inertial mechanisms for laminar-or turbulent-boundary layers, free-molecular or continuum diffusion at high Peclet numbers of d e n s e spherical particles, or fractal agglomerates. The mainstream particle volume distribution is considered to b e log-normal with arbitrary 'spread' parameter, thereby generalizing earlier results for "coagulation-aged'' (self-preserving) distributions. Further generalizations include transitions between important particle transport mechanisms, opening t h e way t o efficient, finite-analytic methods for predicting mass deposition rates for arbitrary, size-dependent particle capture efficiencies.

Monte Carlo Simulation of Particle Aggregation and Simultaneous Restructuring

“…While some of our present simplifying assumptions will have to be relaxed, even our present results for these bivariate population distributions are of potential interest for a number of applications. For example, certain moments of these distribution functions are needed to predict total mass deposition rates on surfaces of particles that have coagulated in the mainstream (30,34,47), the accessible surface area of aerosol populations exchanging heat or mass with their host (carrier) gas (33), loss of accessible area with time of coagulating populations because of diffusional limitations, etc.…”

“…• deposition rates to immersed or containment solid surfaces from coagulating populations across laminar or turbulent boundary layers (30,34,47);…”

AFOSR/ONR Contractors' Meeting on Combustion Rocket Propulsion Diagnostics of Reacting Flow Held in Ann Arbor, Michigan on 19-23 June 1989

“…Of course, particle size and shape also affect Brownian diffusivities, and we are simultaneously developing useful engineering methods for predicting total mass deposition rates from 'coagulation-aged' distributions of particles -including 'fractal' agglomerates (see, e.g., and Rosner & Tassopoulos, 1989). For convective-diffusion deposition Fig.…”

Ash Deposit Formation and Deposit Properties. A Comprehensive Summary of Research Conducted at Sandia's Combustion Research Facility

“…Investigators at the MIT Energy Laboratory [Loehden, Walsh et al 1989] [Srinivasachar and Boni 1989;Boni, Be6r et al 1990;Boni, Johnson et al 1990;Srinivasachar, Helble et al 1990;Snnivasachar, Helble et al 1990;Srinivasachar, Helble et al 1990;Srinivasachar, Helble et al 1990;Srinivasachar, Helble et al 1991;Srinivasachar, Senior et al 1992;Zygarlicke, McCollor et al 1992;Zygarlicke, Ramanathan et al 1992;Benson, Hurley et al 1993] building on published fundamental results [Friedlander and Johnstone 1957;Israel and Rosner 1983;Loehden, Walsh et al 1989;Rosner and Tassopoulos 1989]. The output of these models is a description of the size and elemental composition distributions of the entrained particulate phase resulting from the combustion of pulverized coal.…”

“…Figure 33 for Figure 34 and is defined as the ratio of number of particles that impact the tube surface to the number that are directed at the tube in the free stream. Predictions of the impaction efficiency as a function of particle, gas, and tube properties have been published, at various levels of approximation, by numerous investigators~aitone 1981; Beer and Chigier 1983;Israel and Rosner 1983;Rosner and Tassopoulos 1989;Baxter and DeSollar 1991]. The figure indicates that inertial impaction can be characterized as a function of the particle Stokes Number, which is defined for a cylinder in cross flow as (13) where pP dp and <up represent particle density, diameter, and mean velocity, respectively, and Baxter and Hardesty 1990;Sinquefield, Baxter et al 1998].…”