Oc obe 20 - 22, 2021, B no, Czech Republic, EU
CONTROLLED NANOPARTICLE GROWTH BY VAPOUR CONDENSATION
1Tomáš SITEK, 1Klaudia KÖBÖLOVÁ, 1Ján POLÁČIK, 1S ela VALOVIČ
1 Facul y o Mechanical Enginee ing, B no Uni e si y o Technology, B no, Czech Republic, EU,
Tomas.S[email p o ec ed], Klaudia.Kobolo a@ u b .cz, Ja[email p o ec ed], S ela.Valo ic@ u b .cz
h ps://doi.o g/10.37904/nanocon.2021.4369
Abs ac
Domes ic boile s a e gene ally cha ac e ized by highe emissions o ai bo ne dus . A commonly used
seconda y me hod o educing emissions in he ene gy sec o is a cyclone. Howe e , i s wide expansion in
households is limi ed by, among o he hings, he low e iciency o pa icle cap u e below 1 mic ome e in
diame e , and i is hese sizes ha domina e in he lue gas o domes ic hea ing de ices. By sha ply lowe ing
he empe a u e o he lue gas below he dew poin o he apou , i condenses on all a ailable su aces. This
e ec could inc ease he diame e o he pa icles, which could be sepa a ed wi h highe e iciency. A change
in he nume ical dis ibu ion o he ine pa icles wi h a empe a u e and hus he supe sa u a ion o he lue
gas was sough . The lue gas passed h ough an impinge illed wi h wa e and isop opyl alcohol a h ee
di e en empe a u e egimes. The impinge also se ed o cap u e he condensa e, which was hen subjec ed
o mo phology analysis using an elec on mic oscope and de e mina ion o pa icle dis ibu ion in he
condensa e.
Keywo ds: biomass, pa icula e ma e , combus ion, SEM, SMPS
1. INTRODUCTION
In he las ew decades, in connec ion wi h he en i onmen al impac o combus ion p ocesses, a en ion was
p ima ily paid o gas emissions, bu i is cu en ly shi ing owa ds ine pa icle emissions. Fine pa icles a e a
small liquid and solid ac ion up o 2.5 μm in diame e . In he las ew yea s, he esea che s we e de o ed o
submic on and ul a ine pa icles (up o 0.1 μm), which a ec human heal h signi ican ly. They a e so small
ha he human espi a o y ac does no in e cep hem and hey pene a e di ec ly in o he al eoli [1,2]. Due
o an ac i e su ace, ul a ine pa icles can be much mo e dange ous han he same mass o la ge pa icles
[3,4]. Many esea che s men ion he necessi y o changing he cu en way o emission assessmen [5]. The
c ucial aspec s in ela ion o he impac on human heal h a e he ac i e su ace o he pa icles [6], and hei
abili y o bind oxic subs ances [7] and pene a e in o he lowe espi a o y ac .
The echnologies o ine pa icle educ ion a e di e en . By using a sui able combus ion chambe design and
selec ing he ope a ing pa ame e s we ensu e ha all he ola ile combus ible ma e emains a a high
empe a u e o a su icien ime so ha i ge s combus ed. Howe e , we know om p ac ice ha in eal
combus ion condi ions, a ce ain amoun o non-combus ed subs ances ge in o he a mosphe e. The e o e,
we a e in oducing seconda y sepa a ion o hese pa icles using sui able me hods. In he biomass combus ing
boile s in powe o hea ing plan s, seconda y sepa a ion o dus pa icles is a ma e o cou se. On he o he
hand, small biomass boile s in households do no usually use sepa a ion echnology and hei con ibu ion o
he o al ai pollu ion is conside able [8].
Thus, i is app op ia e o look o ways o minimize he numbe o pa icles emi ed in o he ai by small
combus ion de ices as well. Howe e , PM1 pa icles (size up o 1 μm) a e di icul o sepa a e by he a ailable
me hods. HEPA il e s can sepa a e pa icles o his size, bu he ope a ion o hese de ices is associa ed wi h
high-p essu e loss, high cos and equen main enance equi emen s due o in ensi e clogging [9]. F om he
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g oup o d y sepa a o s, an elec os a ic p ecipi a o [10] is mos o en used o cap u e ine pa icles. Fo small
combus ion plan s, howe e , a majo echnical complica ion is o supply he elec os a ic p ecipi a o wi h
elec ici y o p o ide wa e o we sepa a o s [11]. A bubble column illed wi h wa e is used o we sepa a ion
in expe imen al de ices o labo a o y scale, as in his s udy. In a sa u a ed apou en i onmen , pa icles may
se e as condensa ion nuclei [12]. In such an en i onmen , hese pa icles g ow, and hei sepa a ion becomes
mo e e icien .
2. EXPERIMENTAL METHODS
An au oma ic wood pelle boile EcoSc oll ALFA, specially adap ed o expe imen al pu poses, was used as
he expe imen al combus ion de ice. The nominal he mal ou pu o he boile is 25 kW. As a uel, sp uce wood
pelle s ENplus A1 we e bu ned. The mois u e con en o used uel was a ound 6 %, ash con en was 0.3 % o
aw biomass. The p oxima e analysis was conduc ed by he au ho s acco ding o he Eu opean s anda ds EN
ISO 18134-3 and 18122. Du ing he es s, he boile wo ked a i s nominal ou pu wi h con inuous uel eed. A
sample o lue gas om he boile a app oxima ely 140 °C was aken using a sampling p obe loca ed in he
lue gas s ack, a a heigh o 1 m abo e he ou le o he combus ion de ice (see Figu e 1). This poin was
selec ed in compliance wi h he s anda d equi emen s (EN 13240) o measu ing emissions in small
combus ion de ices. Oxygen con en in he lue gas luc ua ed om 10.0 o 11.5 %, and hus he esul s we e
con e ed o e e ence oxygen con en (10 %).
Figu e 1 Scheme o expe imen al se up
The lue gas wi h dispe sed ine pa icles was ca ied om he s ack h ough he sho ube di ec ly o he i s
impinge . This 250 ml impinge was illed wi h 200 ml o wa e o isop opyl alcohol (so he gas had o pass
h ough app oxima ely 12 cm o liquid) and subme ged in o he wa e ba h. To cool lue gas down, b ine
solu ion (−20 °C a he beginning, bu g adually wa ming up o −8 °C) was used. To wa m lue gas up, ho
wa e was used, which p og essi ely cooled down om 85 °C o 55 °C. Due o he e y low sampling olume
(0.3 li es pe minu e), i was a duous o di ec ly measu e he empe a u e o he lue gas pas he impinge , as
i cooled apidly a he ou le . Ne e heless, we assume he minimal empe a u e di e ence be ween he wa e
ba h and lue gas. Subsequen ly, he gas was ca ied downwa ds o second (again 250 ml), emp y impinge
o collec po en ial condensa e. A e ha , lue gas was ca ied di ec ly o he measu ing de ice. Emp y
impinge wi hou any liquid was used o compa ison as well.
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Fo pa icle concen a ion and dis ibu ion measu emen s, Scanning mobili y pa icle size (SMPS 3080) and
Condensa ion pa icle coun e (CPC 3775) de ices by TSI Inc. we e used. Unsepa a ed pa icles wi h elec ical
mobili y diame e om 18 o 530 nm we e moni o ed o 60 minu es in each se ing.
The mo phology o he pa icles was obse ed using a scanning elec on mic oscope (SEM), pa icula ly he
LYRA 3 (Tescan) elec on mic oscope. Fo he SEM measu emen , he sample was co e ed wi h a conduc i e
laye o gold wi h a hickness o 20 nm using a plane a y o a ion o he samples. A de ec o o seconda y
elec ons (SE) was used o he measu emen s. The elemen al composi ion o he pa icles in he condensa e
was analysed by he ICP-OES spec ome e ARCOS by Spec o.
3. RESULTS AND DISCUSSION
Ini ially, he emp y impinge se ing a oom empe a u e was es ed o ob ain he boile ’s o iginal pa icula e
emissions. Due o he andomness o combus ion p ocesses, 60 one-minu e measu emen s we e a e aged.
Resul s o a e age pa icle numbe concen a ion a e shown in Figu e 2, he unce ain y is exp essed as a
single s anda d de ia ion.
A oom empe a u e, bo h wa e and isop opanol cause a dec ease o numbe concen a ion by 22 %
compa ed wi h emp y impinge . Di e en empe a u e leads o ano he dec ease wi h ambiguous ends. In
he case o wa e , cooling he gas down is mo e e ec i e and esul s in supe sa u a ion and pa icles wi h
condensed wa e apou a e collec ed in he b ine solu ion. On he o he hand, ho wa e c ea es gas wi h
highe absolu e bu lowe ela i e humidi y. In his case, supe sa u a ion is achie ed as soon as lue gas cools
down, which is somewhe e be ween he wo impinge s.
Cold isop opanol does no seem o do much o a di e ence while wa ming i is he mos e ec i e me hod
ega ding pa icle sepa a ion. Ho isop opanol sepa a ed 65 % o he o iginal pa icle numbe concen a ion.
The empe a u e o he ho wa e ba h was e y close o he boiling poin o isop opanol, which caused a
conside able amoun o isop opanol o e apo a e and condensa e in he ube leading downwa ds o he second
impinge . The we inne su ace o he ube and condensa ion o liquid a e cooling a e p obably he main
ac o s.
Figu e 2 A e age pa icle numbe concen a ions
Pa icle diame e s sligh ly inc eased a e passing h ough he wa e compa ed o he emp y impinge
(Figu e 3). In he cold ba h, he pa icles g ew mo e han in he ho ba h o a oom empe a u e condi ions;
he la e wo se ups we e a he simila .
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Isop opanol and wa e cu es a oom empe a u e a e almos indis inguishable. Cold ba h again caused he
bigges inc ease in size, while he ho ba h is he only se up, ha a ec ed he dis ibu ion no iceably and caused
diame e s o dec ease. When he e ec o lowe pa icle concen a ion is dis ega ded, i is clea ly isible, ha
much mo e o he la ge pa icles we e sepa a ed. The e is e en a dec ease in he numbe o smalles pa icles,
which we e una ec ed by o he se ings. Tempe a u e does no appea o ha e a signi ican impac on pa icle
sizes and he size changes a e mo e likely due o he mo e p obable sepa a ion o la ge pa icles.
Figu e 3 A e age pa icle dis ibu ions
Figu e 4 Mo phology o pa icles in condensa e wi h a magni ica ion o 138 000×, measu ing scale is in he
pic u es
A sample o he condensa e wi h cap u ed pa icles om he second impinge was slowly d ied and analysed
by SEM. The e a e wo ypes o pa icles obse ed in he condensa e - sphe ical o o al nanopa icles and
Oc obe 20 - 22, 2021, B no, Czech Republic, EU
egula sphe ical mac opa icles (see Figu e 4). The size o he nanopa icles anges om 45 o 70 nm and
ha o he sphe ical mac opa icles anges om 300 o 350 nm. Bo h ypes o pa icles a e agglome a ed
oge he in o a h ee-dimensional s uc u e, bu nanopa icles a e some imes used oge he almos beyond
ecogni ion. I is no known, how much was he mo phology a ec ed by he hickening o he condensa e, i.e.,
how pa icles looked be o e being sepa a ed. The numbe o sphe ical mac oscopic pa icles in he sample is
conside ably smalle . The exac composi ion o sphe ical pa icles is unknown, bu hei shape indica es phase
change (solidi ica ion) in ligh .
Conce ning me als con en , he mos dominan was po assium and calcium, in smalle amoun s we e de ec ed
also manganese, magnesium and sodium. These esul s a e no su p ise, as hey accoun o mos o he
ino ganic con en in used biomass. No e ha he used measu ing de ice is unable o de ec ca bon and gases
(e.g., oxygen, ni ogen, and hyd ogen), and ca bon and oxygen in pa icula no mally cons i u e a conside able
pa o pa icle mass [13].
4. CONCLUSION
The expe imen s p o ed ha he numbe o ine pa icles o 18 o 530 nm in diame e in he lue gas can be
educed by passing he gas h ough a liquid- illed impinge wi h signi ican e iciency. The e is almos no
di e ence when b ine solu ion o isop opanol is used as a sc ubbing medium a oom empe a u e. Bo h
hea ing and cooling hese liquids esul s in addi ional imp o emen o pa icle sepa a ion. The highes pa icle
sepa a ion e iciency o 65 % was achie ed wi h isop opanol hea ed o empe a u es jus below i s boiling
poin . Condensa ion o isop opanol on pa icles and in ense we ing o su aces caused e en he smalles
pa icles o be cap u ed. In a p ac ical ope a ion, howe e , usage o a lammable and i i an subs ance is no
op imal and usage o egula wa e is much mo e p omising. Hea ing wa e o i s boiling poin could ha e a
simila e ec .
Rega ding mo phology o pa icles collec ed in he condensa e, he ypical soo s uc u es a ound 60 nm in
diame e we e ound as well as la ge sphe ical pa icles wi h diame e up o 350 nm. By analysing me al
con en , simila elemen s as in he o iginal biomass we e ound, such as po assium and calcium.
The o iginal idea o inc easing pa icle diame e s by condensing liquid in hei su aces u ned ou o be mo e
complica ed han expec ed. Condensa ion did occu , bu oo li le o any p ac ical applica ion. I could be
caused by p e e ed condensa ion on su aces o ubes, which a e colde han ae osol pa icles. I his is he
case, usage o la ge diame e ubes would be bene icial.
ACKNOWLEDGEMENTS
This pape was suppo ed by TA ČR wi hin he TJ04000415 p ojec o Sys em o Sepa a ion o Fine
Pa icles om Flue Gas S eam Du ing Biomass Combus ion and Resea ch Cen e o Low-Ca bon
Ene gy Technologies unded as p ojec No. CZ.02.1.01/0.0/0.0/16_019/0000753 by Czech Republic
Ope a ional P og amme Resea ch, De elopmen and Educa ion, P io i y 1: S eng hening capaci y
o high-quali y esea ch and he collabo a ion. This esea ch was u he unded by p ojec s o B no
Uni e si y o Technology: FSIeS-20-6280.
REFERENCES
[1] ROM, William N., MARKOWITZ, S e en MD. En i onmen al and Occupa ional Medicine. 4. Philadelphia, PA:
Lippinco Williams & Wilkins, 2007. ISBN 9780781762991.
[2] U.S. EPA. Ai Quali y C i e ia o Pa icula e Ma e (Final Repo , Ap il 1996). U.S. En i onmen al P o ec ion
Agency, Washing on, D.C., EPA 600/P-95/001. A ailable om:
h p://c pub.epa.go /ncea/ isk/ eco display.c m?deid=2832.

Oc obe 20 - 22, 2021, B no, Czech Republic, EU
[3] WANG, Kun, WANG, Weiye, LI, Lili e al. Seasonal concen a ion dis ibu ion o PM1.0 and PM2.5 and a isk
assessmen o bound ace me als in Ha bin, China: E ec o he species dis ibu ion o hea y me als and hea
supply. Scien i ic Repo s. [online]. 2020, ol. 10, no. 1. ISSN 2045-2322. A ailable om:
h ps://doi.o g/10.1038/s41598-020-65187-7.
[4] MAINKA, Anna and ZAJUSZ-ZUBEK, Elwi a. PM1 in Ambien and Indoo Ai —U ban and Ru al A eas in he
Uppe Silesian Region, Poland. A mosphe e. [online]. 2019, ol. 10, no. 11. ISSN 2073-4433. A ailable om:
h ps://doi.o g/doi.o g/10.3390/a mos10110662.
[5] MERKISZ, Je zy, PIELECHA, Jacek. The Rela ionship be ween Pa icle Mass and Pa icle Numbe . In:
Nanopa icle Emissions F om Combus ion Engines. [online]. 2015, pp. 93-108. ISBN 978-3-319-15927-0.
A ailable om: h ps://doi.o g/10.1007/978-3-319-15928-7_8.
[6] PARK, Minhan, JOO, Hung Soo, LEE, Kwangyul, e al. Di e en ial oxici ies o ine pa icula e ma e s om
a ious sou ces. Scien i ic Repo s. [online]. 2018, ol. 8, no. 1. ISSN 2045-2322. A ailable om:
h ps://doi.o g/10.1038/s41598-018-35398-0.
[7] SCHMID, O ma , STOEGER Tobias. Su ace a ea is he biologically mos e ec i e dose me ic o acu e
nanopa icle oxici y in he lung. Jou nal o Ae osol Science. [online]. 2016, ol. 99, pp. 133-143. ISSN 00218502.
A ailable om: h ps://doi.o g/10.1016/j.jae osci.2015.12.006.
[8] WEIMER, S., ALFARRA, M. R., SCHREIBER, D., MOHR, M., PRÉVÔT, A. S. H. and BALTENSPERGER, U.
O ganic ae osol mass spec al signa u es om wood-bu ning emissions: In luence o bu ning condi ions and
wood ype. Jou nal o Geophysical Resea ch. [online]. 2008, ol. 113, no. D10. ISSN 0148-0227. A ailable om:
h ps://doi.o g/10.1029/2007JD009309.
[9] HWANG, Sungho, ROH, Jaehoon and PARK, Wha Me. Compa ison o he ela i e pe o mance e iciencies o
mel -blown and glass ibe il e media o managing ine pa icles. Ae osol Science and Technology. [online].
2018, ol. 52, no. 4, pp. 451-458. ISSN 0278-6826. A ailable om:
h ps://doi.o g/10.1080/02786826.2017.1423274.
[10] YUAN, Fangyang, YU, Jian eng and ZHENG, Xiangyang. Expe imen al s udy on ine pa icle sepa a ion in a we
elec os a ic classi ie . Chemical Enginee ing and P ocessing - P ocess In ensi ica ion. [online]. 2020, ol. 156.
ISSN 02552701. A ailable om: h ps://doi.o g/10.1016/j.cep.2020.108108.
[11] BIANCHINI, Augus o, PELLEGRINI, Ma co, ROSSI, Jessica and SACCANI, Cesa e. Theo e ical model and
p elimina y design o an inno a i e we sc ubbe o he sepa a ion o ine pa icula e ma e p oduced by biomass
combus ion in small size boile s. Biomass and Bioene gy. [online]. 2018, ol. 116, pp. 60-71. ISSN 09619534
A ailable om: h ps://doi.o g/10.1016/j.biombioe.2018.05.011.
[12] CUI, Lin, SONG, Xiangda, LI, Yuzhong, WANG, Yang, FENG, Yupeng, YAN, Li an a DONG, Yong. Syne gis ic
cap u e o ine pa icles in we lue gas h ough cooling and condensa ion. Applied Ene gy. [online]. 2018, ol.
225, pp. 656-667. ISSN 03062619. A ailable om: h ps://doi.o g/10.1016/j.apene gy.2018.04.084.
[13] JONES, Jenny M, LEA-LANGTON, Amanda R., MA, Lin, POURKASHANIAN Mohamed a WILLIAMS, Alan.
Pollu an s Gene a ed by he Combus ion o Solid Biomass Fuels. [online]. 2014. A ailable om:
h ps://doi.o g/10.1007/978-1-4471-6437-1.