a Co esponding au ho : poko ny.j@ me. u b .cz
Measu emen o ai low and p essu e cha ac e is ics o a an buil
in a ca en ila ion sys em
Jan Poko ný1,a, Filip Poláek1, Miloš Foj lín1, Jan Fiše 1 and Mi osla Jícha1
1B no Uni e si y o Technology, Facul y o Mechanical Enginee ing, Ene gy Ins i u e, Technická 2896/2, B no, Czech Republic
Abs ac . The aim o his s udy was o iden i y a se o ope a ing poin s o a an buil in en ila ion sys em o ou es
ca . These ope a ing poin s a e gi en by he an p essu e cha ac e is ics and a e de ined by a p essu e d op o he
HVAC sys em (ai duc s and en s) and olume ic low a e o en ila ion ai . To co e a wide ange o p essu e
d ops si ua ions, ou cases o en laps se up we e examined: (1) all en s opened, (2) only cen al en s closed (3)
only cen al en s opened and (4) all en s closed. To co e a di e en olume ic lows, he each case was measu ed
a leas o ou di e en speeds o an de ined by he an ol age. I was obse ed ha he p essu e di e ence o he
an is p opo ional o he an ol age and s ongly depends on he h o ling o he ai dis ibu ion sys em by he
se ings o he en s laps. In case o ou es ca we iden i ied co ela ions be ween olume ic low a e o en ila ion
ai , an p essu e di e ence and an ol age. These co ela ions will acili a e and educe ime cos s o he ollowing
expe imen s wi h his es ca .
1 In oduc ion
The amoun o en ila ion ai lowing in o a ca cabin is
impo an pa ame e , which a ec s cabin indoo
en i onmen and HVAC sys em pe o mance. I should
be conside ed al eady in ea ly s age o ca design and has
o be known be o e he new ca se ies a e p oduced o be
able e alua e he e iciency o cabin’s en ila ion, which
has close ela ionship o he d i ing com o and sa e y.
”The sa e y o occupan s o educe d i e a igue, ensu e
good isibili y and main ain com o is key o he
success ul design o such sys ems” [1]. To suppo he
ea ly s age o he HVAC sys em design ou esea ch eam
has been de eloped a Vi ual Tes ing S and o he Ca
Cabin [2], which is a compu a ional model o he
calcula ion o he ca cabin hea load in a ious
en i onmen s. The i s e i ica ion was done [3],
howe e s ill he model needed o imp o e he ad ec ion
pa . The amoun o en ila ion ai and i s dis ibu ion o
he cabin was impo an ask how o imp o e he
ad ec ion scheme o he model.
In his pape he measu emen o amoun o sucked
ai in o he cabin is p esen ed o wide ange o manual
en s se ings. The en ila ion ai dis ibu ion in
au oma ic mode du ing a ious seasons is con empo a y
published in he pape [4]. Aim o his s udy was o ind
co ela ions be ween he se up o an speed, olume ic
low a e and p essu e di e ence o he an o a ious
en ila ion se ups. This s udy we pe o med on he ou
es and he ob ained esul s will be used o subsequen
expe imen s wi hin wo k package Human Cabin Cen ed
Design o he Czech Republic p ojec Jose Božek
Compe ence Cen e o Au omo i e Indus y.
2 Me hods
The e a e plen y o me hods how o measu e ai low
a es h ough en ila ion sys em, which a e based on
a ious physical phenomena, see [5]. Fo example he e
a e mechanical low me e s, di e en ial p essu e
lowme e s (o i ice pla es, Ven u i ubes, e c.) o eloci y
low me e s (Pi o ubes, anemome e s: ane, ho wi e,
lase Dopple , e c.). In ou expe imen we u ilized he las
men ioned ca ego y eloci y low me e s, which iden i y
he low a e by measu ing he ai eloci y and
in eg a ing o e he low a ea. To measu e ai eloci y we
used a couple o ho bulb anemome e p obes
manu ac u ed by Tes o.
The me hod is mo e accu a e when he s illing
channel is used o ensu e ha ai low h ough a duc ing
sys em will be e enly dis ibu ed wi h de eloped ai low
egimes. The olume ic low a e ࢂሶ was a e wa ds
calcula ed om he knowledge o c oss-sec ion a ea ࡿ o
his channel and mean eloci y ࢜
ഥ . Du ing he
expe imen s we also kep knowledge o he ba ome ic
p essu e and ai empe a u e o be able o calcula e ai
densi y ࣋ and hus also mass low a e ࢓ሶ h ough he
en ila ion sys em, see Equa ion 1.
݉ሶ ൌܸ
ሶήߩൌݒҧήܵήߩൌσሺ௩೔
೙
೔సభ ήௌ೔ሻ
ேήߩ (kg·s-1) (1)
DOI: 10.1051/
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Owned by he au ho s, published by EDP Sciences, 201
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EPJ Web o Con e ences ,
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This is an Open Access a icle dis ibu ed unde he e ms o he C ea i e Commons A ibu ion License 4.0, which pe mi s
dis ibu ion, and ep oduc ion in any medium, p o ided he o iginal wo k is p ope ly ci ed.

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2.1 Expe imen al se up
The s illing channel added in on o he es ca suc ion
inle was a plas ic ube o diame e 150 mm and leng h
2000 mm. Because he suc ion inle is loca ed unde he
hood, we had o emo e i o be able p epa e he
expe imen al se up, see Figu e 1 on he le ; on he igh
side, he e is shown he ing a ound he c oss-sec ion
a ea, which was loca ed in he middle o he ube’s leng h
o loca e measu ing axis un . The ing we used o be e
Figu e 1. Expe imen al se up. On he le : S illing channel
du ing measu emen s. On he igh : he ing a ound he c oss-
sec ion a ea o ube whe e he p obes we e placed (axis loca ion
+x=45 ° +y= 135° om he ho izon al plane).
Du ing he es he ca engine was idling o ensu e ha
he an be powe ed wi h same powe as du ing eal a ic
codi ions (supply ol age abou 13.8 V). Fo he
measu emen o he ol age we used classical mul i-me e
and o he measu emen o he p essu e di e ence we
used Tes o 435 wi h a build p essu e senso . The alue o
p essu e di e ence was eco ded manually en imes o
he each es case. In he case o ai eloci y we eco ded
measu emen au oma ically wi h sampling a e 1 Hz. We
used wo ho bulb anemome e s connec ed o da a logge
Tes o 350 M/XL. The each poin was measu ed o i e
seconds and o he i e seconds we e used o he
changing posi ion o he p obes in he ube. The posi ion
o he p obes in he ube was se up acco ding o he
heo y see [6] using he Equa ion 2.
ݎ௜ൌܴήඥሺʹ݅െͳሻ ʹܰ
Τ (m·s-1) (2)
whe e R = 75 mm is diame e o he ube and N = 7 is
numbe o a e sed lines in each hal -axis. Using his he
app oach i allows o spli c oss-sec ional a ea o ube
(176.7 mm2) in o 28 sec o s o equal a eas. Fo each
sec o was measu ed one ai eloci y a i s cen e and
hen we calcula ed he mean eloci y ࢜
ഥ simply as he
a e age alue o hese local eloci ies. Addi ionally we
measu ed he cen al poin [x=0, y=0], so all oge he i
coun s 29 poin s o measu e o each es case. Howe e
cen al poin no en e o he calcula ion o mean eloci y,
because his poin s ep esen s annulus o ze o a ea (see
Figu e 2).
2.2 Unce ain ies
To ob ain a ep esen a i e iew abou a low egime
inside he ube he ai eloci y a he c oss-sec ion‘s
a e se lines (x, y axis) was measu ed epea edly. Fo
each en ila ion se up i was a e sed i e imes o be
able e alua e unce ain y componen s: o ype A. In his
case he s anda d unce ain y ࢛࡭ can be associa ed wi h
s anda d de ia ion o he mean. We applied his o he
ai eloci y and ob ained he Equa ion 3.
ݑ஺ൌ݇௨஺ ήටଵ
௡ሺ௡ିଵሻσሺݒ௜െݒҧሻଶ
௡
௜ୀଵ (m/s) (3)
whe e ࢑࢛࡭ ൌ૚Ǥ૝ is sa e y ac o o numbe o
epe i ion ࢔ൌ૞. Then he expanded unce ain y o he
95 % con idence in e al is UA = 2·uA, whe e 2 is he
ele an co e age ac o , see [7]. The unce ain y o ype
B co esponding o he accu acy o measu emen de ices
was neglec ed in his s udy.
2.3 Measu emen schedule
The measu emen schedule included es cases combining
ou di e en an speed (le el 2, 3, 4, 6) and ou
di e en con igu a ions o closing en laps (“all en s
opened”, “only cen al en s closed”, “only cen al en s
opened” and “all en s closed”). We manipula e only
wi h he laps o he dashboa ds en s ( wo a cen e and
wo a sides) and wi h wo unnel en s o ien ed o he
ea sea . These con igu a ion we e chosen wi h espec
o he co e a wide ange o en ila ion sys em
ope a ional condi ions. We measu ed all men ioned
combina ion which ises ma ix 4x4 o examined es
cases, see Table 1.
3 Resul s
In he i s subchap e , he e is demons a ed how he
olume ic and mass low a e we e e alua ed h ough he
measu emen o ai eloci ies, which was he mos ime
consuming p ocedu e o he expe imen . The p ocedu e is
desc ibed o he es case S6-C1, see Table 1. In he
second subchap e a summa y o esul s o all es cases is
p esen ed and in he hi d one he esul ing p essu e-
olume cha ac e is ics a e plo ed.
3.1 Tes p ocedu e o pa icula es case
Du ing he es case S6-C1 ( an speed se up o 6 h le el
and only cen al en s opened) he mean ai empe a u e
was 25.4 °C and ba ome ic p essu e was 102 375 Pa,
which implies ai densi y ߩ = 1.194 kg/m3. Vol age on
he an was du ing he es almos cons an U = 11.4 V
and p essu e di e ence a an p = 325.2 Pa was qui e
s able as well (mos ly i was be ween 320 and 328 Pa).
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Figu e 2. Tes case S6-C1. Measu ed eloci y p o ile in he
ube wi h 28 equal a eas o c oss-sec ion.
The measu ed alues o ai eloci ies in speci ic poin s o
he c oss-sec ion a ea o s illing channel a e plo ed in
Figu e 2. The e a e illus a ed loca ion and measu ed
alues o all 28 sec o s, which implies he mean eloci y
ݒҧ ൌ͸ǤͲͲേͲǤ͸Ͳ݉Ȁݏ. Hence by using he Equa ion 1
he olume ic low a e was ܸሶ = 106.0 l/s and mass low
a e ݉ሶ =126.5 g/s.
In Figu e 3, he e a e shown he eloci y p o iles o
he x-axis and y-axis, wi h e o ba s showing he alue
o expanded s anda d de ia ion ܷ஺ o each poin . I can
be seen ha he ai low in he s illing channel had almos
ully de eloped u bulen low egime wi h he maximal
eloci y in he cen e. Fo example, in he case S6-C1, he
highes alue o ܷ஺ was o he poin on y-axis y=+72
mm, whe e = 5.71 ± 1.40 m/s. The indi idual ime
samples we e [7.17, 5.91, 4.02, 5.63, 5.81]. On he o he
hand he lowes s anda d de ia ion was o he poin on x-
axis x=+66 mm, whe e = 5.27 ± 0.18 m/s. The
indi idual ime samples we e [5.21, 5.53, 5.22, 5.27,
5.13]. These unce ain ies a he han ou line some
luc ua ions in low s uc u e inside a ube, ep esen s he
p ecision o he measu emen a gi en poin .
Figu e 3. Tes case S6-C1. Measu ed eloci y p o iles and he
mean eloci y (poin = 0 mm no en e o i s calcula ion).
3.2 Fan and duc ing sys em cha ac e is ics
All iden i ied ope a ing poin s a e no ed in Table 1. Each
poin is de ined by an se up, en laps con igu a ion,
alue o olume ic low a e and p essu e di e ences.
F om his able we e plo ed g aphs in Figu e 4 and
Figu e 5, ep esen ing ope a ing poin s o he an and
duc ing sys em, espec i ely.
The an cha ac e is ics exp esses how he speci ic an
o ou es ca wo ks du ing a ious in ensi y o
en ila ion, which depends on he an speed and hus also
on he ol age o he an. We de i ed o he an a
eg ession model using he polynomials o 2nd o de see
Figu e 4. I can be seen ha in he case S2 he olume ic
low a e is e y sensi i e o he p essu e di e ence.
F om his eason we no measu e he case S1, because he
ange o p essu e di e ence is in o de o uni s o Pascals
which is close o he accu acy o he Tes o de ice. On he
o he hand wi h he highe speed o an he ange o
p essu e di e ences espec o he ange o olume ic
low a e is inc easing and hus he in e p e a ion o
esul s should be mo e eliable.
Table 1. Ma ix o all measu ed es cases
Fan se up C1: all
opened
C2: only
cen al
closed
C3: only
cen al
opened
C4: all
closed
S2:
U = 4.8 V
42.3 l/s
99.8 Pa
39.8 l/s
110.2 Pa
35.9 l/s
112.4 Pa
23.9 l/s
124.3 Pa
S3:
U = 6.1 V
53.0 l/s
148.4 Pa
48.2 l/s
160.3 Pa
45.3 l/s
165.3 Pa
31.5 l/s
192.1 Pa
S4:
U = 7.6 V
75.4 l/s
208.8 Pa
69.2 l/s
214.8 Pa
65.0 l/s
227.8 Pa
47.1 l/s
269.5 Pa
S6:
U = 11.4 V
106.0 l/s
322.5 Pa
97.5 l/s
368.8 Pa
91.9 l/s
395.1 Pa
76.4 l/s
492.6 Pa
Figu e 4. Fan cha ac e is ics
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Figu e 5. Duc ing sys em cha ac e is ics
The duc ing sys em cha ac e is ics exp ess he ela ion
be ween he di e ence p essu e and he olume ic o
he speci ic duc ing sys em. The mos in e es ing cu es
a e C1 and C4, which de ines a h esholds o possible
low condi ions h ough he gi en duc ing. We de i ed
o he he duc ing also a eg ession model based on
polynomials o 2nd o de see Figu e 5.
The main esul s o his expe imen a e iden i ied
eg ession cu es o he an and duc ing sys em inside
ou es ca . I we plo he an cu es and duc ing sys em
cu es o e hemsel es, we ob ain om hei
in e sec ions he ope a ing poin s, which we al eady
measu ed. Howe e he ad an age is ha i is possible o
change he ype o an on he cu en duc ing, o also i is
possible o change duc ing sys em o he cu en an o
ob ain new ope a ing poin s.
4 Discussion
The expe imen s shown ha he ol age o he an is
linea ly p opo ional o he use se ings o an con olle ,
as well as he olume ic low a e see Figu e 6. I is
e iden ha he speed o an no de ine olume ic low
a e unambiguously, because he e is s ong in luence o
how he en ila ion duc ing sys em is h o led by en
laps se ings. This is he main bene i o ou expe imen ,
o conside ed p essu e - olume ic low a e
cha ac e is ics o en ila o (Figu e 4) and duc ing sys em
(Figu e 5) o be able co e all possible se ings o
en ila ion con ol (de os , au oma ic mode, closing o
manual se up o en laps, e c.)
Figu e 6. Speed o an e sus olume ic low a e.
The posi ioning o he p obes we e done manually, so he
e o o as ening and posi ing could occu and sligh ly
in luence pa icula measu ed poin . S ill he s anda d
de ia ion (con idence in e al 95 %) du ing he
measu emen we e accep able gene ally and he
anemome e based me hod shows a good epea abili y.
The highes s anda d de ia ions o eloci y we e
nea he wall. We assume ha is due o he highe
eloci y g adien a he wall, which caused ha he
measu ed alues we e mo e sensi i e o p ecise p obe
loca ion. The highe accu acy o he measu emen could
be achie ed by inc easing o epe i ion o measu emen
om 5 o example o 10. Howe e we chose n = 5 due o
he ac ha he measu emen would be oo ime
consuming in case o 10 and he ݇௨஺ ac o would no
change signi ican ly. The s illing channel
imp o ed he s abili y o low a lo and educe he
luc ua ions which occu di ec ly be o e he suc ion inle
o he en ila ion sys em. The peak in he eloci y p o ile
(Figu e 3) a he cen e o channel c oss-sec ion can be
explained by he ac ha all poin s we e measu ed by
wo p obes simul aneously, howe e in case o cen al
poin i was used only one p obe. Ne e heless he alue
o cen al poin was no conside ed in he calcula ion o
he mean eloci y and olume ic low a e.
5 Conclusion
We iden i ied an and en ila ion duc ing sys em
cha ac e is ics desc ibing co ela ions be ween
olume ic low a e, se up o en ila ion sys em and
p essu e di e ence a he an. Ob ained co ela ions a e
alid only o an and duc ing sys em o ou es ca , bu
e en so hey will allow e alua e olume ic low a e o
ai di ec ly om he an p essu e di e ence. This
app oach will acili a e and educe ime cos s o he
consequen expe imen s wi h ou es ca subs an ially.
Acqui ed knowledge is possible o use no only o
clima ic chambe es s, bu e en o eal a ic condi ions
measu emen s.
Acknowledgemen
The esea ch was suppo ed by he p ojec Reg. No. FSI-
S-14-2355 o he B no Uni e si y o Technology; he
p ojec LO1202 Ne me Cen e Plus wi h he inancial
suppo om he Minis y o Educa ion, You h and
Spo s o he Czech Republic unde he "Na ional
Sus ainabili y P og amme I" and he p ojec o he Jose
Božek Compe ence Cen e o Au omo i e Indus y
TE01020020.
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