Showing papers in "Aerosol Science and Technology in 1981"
TL;DR: Lee et al. as mentioned in this paper used a filter efficiency measuring technique based on the use of moderately monodisperse aerosols and an electrical aerosol detector to measure the filtration efficiencies of uniformly sized fibers.
Abstract: Submicron aerosol filtration by fibrous filters has been studied experimentally employing a filter efficiency measuring technique based on the use of moderately monodisperse aerosols and an electrical aerosol detector. Using this technique, the filtration efficiencies of filters made of uniformly sized fibers have been measured by the use of particles in the 0.035–1.3 μm diameter range. Filter solidity has ranged from 0.0086 to 0.42. Filtration velocity has been varied between 1 and 300 cm/sec. The results of the measurement have been compared quantitatively with the available theories. It has been found that theories taking into account the interference effect of neighboring fibers are in reasonable agreement with the experiments. * This paper is based on the thesis of K. W. Lee in partial fulfillment of the requirements for the Ph.D. Degree at the University of Minnesota.
151 citations
TL;DR: The diesel passenger car offers a substantial advantage in fuel economy over its gasoline-powered counterpart, but the long-range future of the diesel in this application is threatened by future federal standards on exhaust particular emissions as discussed by the authors.
Abstract: The diesel passenger car offers a substantial advantage in fuel economy over its gasoline-powered counterpart, but the long-range future of the diesel in this application is threatened by future federal standards on exhaust particular emissions. These particulates are primarily combustion-generated carbonaceous soot in combination with a solvent-extractable hydrocarbon fraction. Particulate production involves an incompletely understood series of phenomena that includes nucleation, surface growth, agglomeration, dehydrogenation, oxidation, and adsorption and condensation of gaseous hydrocarbons. The contemporary state of understanding of these events is reviewed as they apply to the passenger-car diesel engine.
129 citations
TL;DR: In this article, a method for calculating the electromagnetic scattering properties of a cluster of spheres of arbitrary radii and (possibly complex) refractive indexes is proposed, taking proper account of multiple scattering effects and does not require any approximation except for the truncation of the multipolar expansions describing the scattered field.
Abstract: A method for calculating the electromagnetic scattering properties of a cluster of spheres of arbitrary radii and (possibly complex) refractive indexes is proposed. The approach takes proper account of multiple scattering effects and does not require any approximation except for the truncation of the multipolar expansions describing the scattered field. The convergence of the expansions is tested through the application to the simple but significant system of two spheres with varying interparticle separation.
92 citations
TL;DR: A review of current ideas about possible mechanisms for formation of combustion aerosols is presented in this article, where available data regarding fly ash size distribution and elemental concentrations in various size fractions were analyzed.
Abstract: The composition and size distribution of particles emitted by coal combustion sources depend upon various mechanisms leading to their formation. A review of current ideas about possible mechanisms for formation of combustion aerosols is presented. Available data regarding fly ash size distribution and elemental concentrations in various size fractions were analyzed. These data were qualitatively compared with theoretical model predictions to indicate the relative contributions of various mechanisms in the formation of aerosols.
86 citations
TL;DR: In this article, a generalized cross validation (GXV) algorithm for inversion of aerosol data has been proposed, based on the concept of generalized cross-validation.
Abstract: The determination of an aerosol size distribution from conventional data is an ill-posed problem. The general characteristics of the aerosol size distribution inversion problem are discussed, and several existing methods are assessed. A new algorithm, in the spirit of Twomey's constrained linear inversion algorithm, employing the concept of generalized cross validation is developed. Extensive numerical tests on simulated data from a Marple impactor show superior performance of the method. Different versions of the algorithm are available based on different choices of the function spaces in which the assumed distributions lie. The new algorithm offers promise as the most accurate now available for inversion of aerosol data.
74 citations
TL;DR: In this article, a Utah subbituminous coal was burned at a rate of 0.5-1.5 kg/hr and at fuel-lean conditions in a laboratory furnace.
Abstract: This paper discusses the influences observed in laboratory pulverized coal combustion experiments. A Utah subbituminous coal was burned at a rate of 0.5–1.5 kg/hr and at fuel-lean conditions in a laboratory furnace. Experiments were conducted using a number of burners and at a range of combustor wall temperatures. Gaseous and particulate combustion products were sampled downstream of a series of convective heat exchangers. The variation of the mass and composition of the submicron particles with burner aerodynamics and heat transfer rate are discussed, and the relationship between the laboratory observations and aerosols produced by utility boilers is explored.
57 citations
TL;DR: An aerosol reactor is a gaseous system in which fine particles are formed by chemical reaction in either a batch or flow process as mentioned in this paper, the particle sizes of interest range from less than 10 A (molecular clusters) to 10μm.
Abstract: An aerosol reactor is a gaseous system in which fine particles are formed by chemical reaction in either a batch or flow process. The particle sizes of interest range from less than 10 A (molecular clusters) to 10μm. Such reactors may be operated to study the aerosol formation process, as in a smog reactor, or to generate a product such as a pigment or a catalytic aerosol. Aerosol reactors can be characterized by three temporal or spatial zones or regions of operation for batch and flow reactors, respectively. In zone I, chemical reaction results in the formation of condensable molecular products which nucleate and form very high concentrations of small particles. The number density depends on the concentration of preexisting aerosol. Zone II is a transition region in which the aerosol number concentration levels off as a result of hetergeneous condensation by the stable aerosol. In zone III coagulation becomes sufficiently rapid to reduce the particle number concentration. There may be a zone IV in which...
26 citations
TL;DR: In this article, the authors characterized the aerosol emitted by a moderately large smoldering combustion source (16 cm in diameter) and found that the average particle size of the resulting aerosol requires a sevenfold greater concentration to trigger an ionization detector.
Abstract: The aerosol emitted by a moderately large smoldering combustion source (16 cm in diameter) has been characterized in detail. The fuel is a permeable bed of cellulosic insulation (wood fibers) receiving its primary air supply by flow up from the bottom of the bed while the smolder wave propagates downward. The mass mean particle size of the aerosol is 2–3 μm; this shows no clear trend with smolder wave depth in the bed or with air flow velocity. The large average particle size is shown to imply that, compared to punk smoke, the present aerosol requires a sevenfold greater concentration to trigger an ionization detector. Coagulation of the aerosol in the plume above the source is shown to be minimal, but substantial coagulation can occur within the source. The apparent fractional conversion of gasified mass (60–75% of the fuel) to aerosol mass decreases with smolder wave depth in the bed and with decreasing air flow rate. The mass and number flow rate of the aerosol show these same trends. The decreasing ae...
19 citations
TL;DR: In this article, the acoustic hydrodynamic turbulence-turbulence interaction in a resonance tube is investigated, and a numerical calculation of the turbulent agglomeration kernel KT is performed.
Abstract: The potential applications of acoustic agglomeration of aerosols in industry are usually under high flow rate conditions. The acoustic hydrodynamic turbulence-turbulence interaction in a resonance tube is the subject of this investigation. Measurements are made at both loop and node positions with a sound pressure level of 161.5 dB (re 20 μPa) and hydrodynamic Reynolds number Re ranging from 0 to 14000. Important parameters of the final state such as the rms turbulent velocity, the integral scale, the Taylor and Kolmogorov microscales, and the rate of turbulent energy dissipation ∈ are estimated. It is found that as long as the hydrodynamic flow is turbulent ∈ increases monotonically with increasing values of Re. Furthermore, ∈ is consistently larger at loop than at node. Based on this information, a numerical calculation of the turbulent agglomeration kernel KT is performed. The strong enhancement of the turbulence-turbulence interaction on KT at higher values of the Reynolds number Re indicates that the...
11 citations