| 1. |
- Karlsson, Martin, et al.
(författare)
-
Size- and compostition-controlled Au-Ga aerosol nanoparticles
- 2004
-
Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 1521-7388 .- 0278-6826. ; 38:9, s. 948-954
-
Tidskriftsartikel (refereegranskat)abstract
- A simple gas-phase method has been developed for producing size- and composition-controlled nanoparticles of binary alloys. The process includes the formation and classification of aerosol nanoparticles of one material and the subsequent condensation of a controlled shell of another. The shell thickness is controlled by the evaporation temperature of the second material. Here we study the Au-Ga system with particle compositions ranging from pure Au to 50 atomic percent Ga. Transmission electron microscopy was used to study the morphology, composition, and structure of the generated particles.
|
|
| 2. |
- Martinsson, B. G., et al.
(författare)
-
Methodology to estimate the transfer function of individual differential mobility analyzers
- 2001
-
Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 0278-6826 .- 1521-7388. ; 35:4, s. 815-823
-
Tidskriftsartikel (refereegranskat)abstract
- A method to estimate the nonideal features of the transfer function of individual differential mobility analyzers (DMA) was developed and tested experimentally. This was up to now an unsolved problem, which is important for the precision in DMA measurements. The method involves three DMAs of unknown characteristics, which are used in three rounds of experiments with two DMAs according to a fixed schedule. The width of the transfer functions of the three DMAs is obtained in a single fitting procedure where one parameter is fitted to each DMA transfer function and the particle losses in each DMA are calculated in direct relation to that parameter and parameters known from the experiment. It was shown that the proposed method could solve the apportioning problem and unambiguously estimate the transfer function width and the particle losses in each of the DMAs.
|
|
| 3. |
- Nerbrink, OL, et al.
(författare)
-
Effect of humidity on constant output and breath enhanced nebulizer designs when tested in the EN 13544-1 EC standard
- 2003
-
Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 1521-7388 .- 0278-6826. ; 37:3, s. 282-292
-
Tidskriftsartikel (refereegranskat)abstract
- Aqueous aerosols produced by nebulizers used in clinical situations can rapidly change size as the patient inhales. This is caused by air with a relative humidity (RH) lower than inside the nebulizer being entrained and mixed with nebulized aerosol during the inhalation maneuver. A way to assess the change in size is to measure the aerosol in a test method that reflects the clinical situation. The EC standard, EN 13544-1, offers a first step towards this assessment. In this paper we have tested two nebulizer designs, one conventional constant output nebulizer and one breath-enhanced nebulizer, using the proposed standard in order to assess the effect of the relative humidity of entrained ambient air on nebulized aerosol size properties. The results indicate that aerosol size from the conventional nebulizer is greatly affected by the RH of the entrained air, while the breath-enhanced nebulizer is not affected. The results agree with theoretical expectations of how the entrained air interacts with nebulized aerosol. In the breath-enhanced nebulizer, the air is passed through the nebulizer interior and becomes saturated with moisture drawn from the relatively large nebulizer reservoir solution. With the conventional constant output nebulizer, ambient air is drawn over the nebulizer and draws its moisture from the relatively small volume of nebulized aerosol released from the nebulizer. For the conventional nebulizer design, we found a large decrease in measured nebulized aerosol size with decreasing relative humidity-3.1 mum MMAD at 75% RH fell to 1.9 mum MMAD at 20% RH. For the breath-enhanced nebulizer design, the MMAD was stable between a similar humidity range. The results indicate that aerosol size is dependent on relative humidity of the entrained air for the constant output jet nebulizer design that has no air entrainment through the nebulizer. We found no significant effect of ambient humidity of entrained air on nebulized aerosol size from the breath-enhanced nebulizer design.
|
|
| 4. |
- Strand, M, et al.
(författare)
-
Laboratory and field test of a sampling method for characterization of combustion aerosols at high temperatures
- 2004
-
Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 1521-7388 .- 0278-6826. ; 38:8, s. 757-765
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to design and experimentally examine a sampling method for high-temperature aerosols from biomass combustion, in which nucleation and condensation from fly ash forming vapors is controlled. The sampling method includes a high-temperature probe in which the hot gas is diluted and then cooled. Laboratory results from sampling a model aerosol with known concentrations of SiO2 particles and KCl vapor showed that when using a high dilution ratio, the KCl vapor was effectively separated from the aerosol by deposition onto the probe walls. When a lower dilution ratio was used, the KCl vapor generated a distinct nucleation mode when cooled in the probe. The sampling method was also used for sampling flue gas from a circulating fluidized bed boiler fired with forest residues. The results suggest that the major fractions of Ca, K, S, and Zn were present as particles at 780degreesC, whereas most of the Cl and Pb were present as gases. The field results are consistent with results previously reported and indicate that the method can be used for efficient and precise characterization of high-temperature combustion aerosols containing inorganic vapors.
|
|
| 5. |
- Svane, Maria, 1957, et al.
(författare)
-
Chemical analysis of individual alkali-containing aerosol particles: Design and performance of a surface ionization particle beam mass spectrometer
- 2004
-
Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 0278-6826 .- 1521-7388. ; 38:7, s. 655-663
-
Tidskriftsartikel (refereegranskat)abstract
- A mobile particle beam mass spectrometer has been developed to measure the alkali metal content in individual submicron aerosol particles. The instrument employs an aerodynamic inlet system for efficient sampling of particles into vacuum, and the detection of individual particles is based on decomposition and surface ionization on a hot platinum surface. A boxlike design of the hot ionizing surface is shown to limit problems associated with particle bounce effects and incomplete ionization, and the decomposition/ionization process is not sensitive to detailed particle properties. High transmission efficiencies and quantitative determination of the alkali metal content in individual particles with diameters down to 14 nm are demonstrated. Experiments with particles doped with alkali salt show that the size range may be extended down to a few nanometers after further improvements of the inlet system. High size resolution can be achieved with the instrument for particle sizes down to tens of nanometers, as illustrated by the detection of multiply charged particles passing through a DMA. The robustness of the instrument makes it suitable for field measurement applications, and the technique is demonstrated at a 12 MW biomass combustion facility. The performance of the instrument and further refinements of the technique are discussed, and potential applications in field and laboratory studies are outlined.
|
|
| 6. |
- Tran, K. Q., et al.
(författare)
-
A novel particle trap impactor for use with the gas-quenching probe sampling system
- 2004
-
Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 0278-6826 .- 1521-7388. ; 38:10, s. 955-962
-
Tidskriftsartikel (refereegranskat)abstract
- A novel particle trap impactor has been developed for use with the gas-quenching probe in order to exclude solid particles from entering into the probe during sampling of gaseous metallic species in fluidized bed combustion conditions. The impactor must be small in size (empty set(impactor)less than or equal toempty set(probe) = 45 mm) but capable of collecting a relatively large amount of particles at elevated temperatures. As the first step, the impactor was designed, constructed, and tested at room temperature for KCl aerosol particles. The impactor with a nozzle of 0.95 mm in diameter, in combination with the orifice-to-jet diameter ratio of 1.5 and the ratio of the jet-to-plate spacing to jet diameter at 1.4 yielded a sharp cutoff curve with a maximum collection efficiency of about 0.9 and a rootStk(50) value of about 0.22. In addition, the collection efficiency of the impactor was compared with the particle removal efficiency of a filter of the same type as the filter previously used with the gas-quenching probe. The difference from the comparison is very small, indicating that the impactor can be used to replace the filter to prevent fly ash particles from entering the gas-quenching probe in fluidized bed combustion conditions.
|
|
