Electrical separation for generating standard aerosols in a wide particle size range
Date
2011-07-19
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Abstract
Käesoleva töö teemaks on aerosooliosakeste elektriline separeerimine kui meetod standardaerosoolide genereerimiseks. Esmalt antakse lühike ülevaade erinevatest meetoditest standardaerosoolide genereerimiseks ning lähemalt vaadeldakse ühte neist – elektrilist separeerimist. Kirjeldatakse kordsete laengute probleemi, mis kaasneb suurte osakeste elektrilise separeerimisega. Selle lähemaks uurimiseks tuuakse sisse uus parameeter – standardaerosooli kvaliteet. Uuritakse kvaliteedi sõltuvust aerosooli genereerimise protsessi algparameetritest, järeldusega, et tavameetodid elektrilise separeerimise rakendamiseks ei anna alati piisavalt kõrge kvaliteediga standardaerosooli. Sellest tulenevalt esitatakse uut meetodit, mis võimaldab saada kõrge kvaliteediga standardaerosooli osakeste suuruse laias vahemikus. Antud meetodit uuritakse eksperimentaalselt; saadud tulemused kinnitavad teoreetilisi eeldusi. Seejärel tutvustatakse ainulaadset diferentsiaalset liikuvusanalüsaatorit, kirjeldatava meetodi rakendamiseks suurte aerosooliosakeste juures. Antud instrumenti uuritakse teoreetiliselt ja eksperimentaalselt ning saadud tulemused kinnitavad ootuspärast käitumist. Siinjuures rakendatakse liikuvusanalüsaatori põhiparameetri – ülekandefunktsiooni määramiseks uudset meetodit, kasutades polümeer-osakestel põhinevat aerosooli suurusstandardit.
The main subject of this thesis is the generation of standard aerosols for instrument calibration by means of electrical separation of charged aerosol particles. The need for instrument calibration and the methods for doing it are briefly discussed. Then, electrical separation as one of the means for producing aerosols for instrument calibration is examined in more detail. An overview of the method is given and challenges in using it are described. The problem of multiple charges, when using electrical methods for standard aerosol generation, is examined. From this, a parameter for describing an electrically generated standard aerosol – aerosol quality – is presented. Dependence of the quality on several initial parameters of aerosol generation process is examined with a conclusion, that obtaining high quality by conventional means can be difficult. Next, a method for obtaining higher quality standard aerosol is presented and described in detail. It is experimentally shown that this method allows reliably to obtain high quality standard aerosols in a wide particle size range. A design of a Differential Mobility Analyzer is briefly described that makes it possible to use the previously described method for standard aerosol generation with larger aerosol particles. The performance of the DMA is evaluated both theoretically and experimentally and it is found to be within expected margins. A new method, using monodisperse polymer size standards for the assessment of the main characteristic of the DMA – its transfer function – is described for the large particle region.
The main subject of this thesis is the generation of standard aerosols for instrument calibration by means of electrical separation of charged aerosol particles. The need for instrument calibration and the methods for doing it are briefly discussed. Then, electrical separation as one of the means for producing aerosols for instrument calibration is examined in more detail. An overview of the method is given and challenges in using it are described. The problem of multiple charges, when using electrical methods for standard aerosol generation, is examined. From this, a parameter for describing an electrically generated standard aerosol – aerosol quality – is presented. Dependence of the quality on several initial parameters of aerosol generation process is examined with a conclusion, that obtaining high quality by conventional means can be difficult. Next, a method for obtaining higher quality standard aerosol is presented and described in detail. It is experimentally shown that this method allows reliably to obtain high quality standard aerosols in a wide particle size range. A design of a Differential Mobility Analyzer is briefly described that makes it possible to use the previously described method for standard aerosol generation with larger aerosol particles. The performance of the DMA is evaluated both theoretically and experimentally and it is found to be within expected margins. A new method, using monodisperse polymer size standards for the assessment of the main characteristic of the DMA – its transfer function – is described for the large particle region.
Description
Väitekirja elektrooniline versioon ei sisalda publikatsioone.
Keywords
aerosoolid, separeerimine, aerosols, separations