A water-based condensation particle counter (CPC) TSI 3785 is a new step for the ultrafine particle measurement technique. A new instrument was examined in this study. Detection efficiency was investigated experimentally using different temperatures of the saturator and of the growth tube. The experiments showed that detection efficiency can be improved by increasing the temperature of the growth tube and decreasing the saturator temperature. Fitting a two-free parameter equation to the experimental data, the cut-sizes D_50% were determined. The determined cut-sizes were comparable with the other three widely used fitting equations. The cut-sizes were studied by changing the growth tube temperature from 40 to 65 °C and varying the saturator temperature from 10 to 30 °C. For the purpose of the study, the instrument operation regime (saturator and growth tube temperatures) can be optimised by selecting the needed cut-size. The cut-sizes can be changed in a wide range. The smallest detected cut-size D_50% was 4.2 nm, and the largest 14.6 nm. In the default operation regime, the instrument cut-size was 5.9 nm. The detection efficiency of the studied TSI CPC 3785 was compared with the ultrafine TSI CPC 3786. The results showed that the studied CPC can be optimised to the regime having a smaller cut-size than the cut-size of the ultrafine CPC in the default regime. Thus, the tested TSI CPC 3785 had the lowest detection limit ( D_50%) of 4.2 nm, and the TSI CPC 3786 had 4.6 nm for the silver particles.
Keywords: detection efficiency, condensation particle counter, ultrafine particles
PACS: 92.60.MZ, 92.20.Bk

VANDENS KONDENSACINIO DALELIŲ SKAITIKLIO DARBO REŽIMO OPTIMIZAVIMAS
G. Mordas^a, T. Petäjä^b, V. Ulevičius^a
aValstybinis mokslinių tyrimų institutas Fizinių ir technologijos mokslų centras, Vilnius, Lietuva
^bHelsinkio universiteto Fizinių mokslų fakultetas, Helsinkis, Suomija

žingsnis ultrasmulkiųjų aerozolio dalelių matavimo technikoje. Straipsnyje pateikiami šio skaitiklio eksperimentinių tyrimų duomenys. Įvertintas aerozolio dalelių registravimo efektyvumas kaip dalelių dydžio funkcija, garų prisotinimo ir aerozolio dalelių augimo kamerose naudojant skirtingą temperatūrą. Nustatyta, kad dalelių registravimo efektyvumas gali būti pagerintas didinant dalelių augimo kameroje temperatūrą ir mažinant temperatūrą garų prisotinimo kameroje. Eksperimentiškai nustatytos registravimo efektyvumo vertės buvo aprašytos dviejų laisvų parametrų funkcija ir ją taikant buvo įvertinti registravimo efektyvumo ribiniai dydžiai ( D_50%). Ribiniai dydžiai paklaidų ribose sutampa su dydžiais, nustatytais naudojant kitas metodikas. Registravimo ribiniai dydžiai buvo įvertinti naudojant garų prisotinimo ir dalelių augimo kamerose skirtingas temperatūras. Eksperimento metu dalelių augimo kameroje temperatūra buvo kečiama nuo 40 iki 65 °C, o garų prisotinimo kameroje – nuo 10 iki 30 °C. Mažiausias nustatytas registravimo ribinis dydis buvo 4,2 nm, o didžiausias – 14,6 nm. Gamintojo nustatytame veikimo režime sidabro dalelėms ribinis dydis yra 5,9 nm. Tiriamo TSI 3785 kondensacinio dalelių skaitiklio registravimo efektyvumas buvo palygintas su kito, itin smulkias daleles registruojančio, kondensacinio skaitiklio TSI 3786 efektyvumu. Eksperimento rezultatai parodė, kad testuojamo TSI 3785 prietaiso veikimo režimas gali būti optimizuotas ir turėti mažesnę ribinio dydžio vertę (4,2 nm) nei itin smulkių dalelių skaitiklis TSI 3786 (4,6 nm), dirbantis gamintojo nustatytame veikimo režime.

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