a Co esponding au ho : [email protected]
The de e mina ion o ield usabili y o me hod measu ing empe a u e
ields in he ai using an in a ed came a
Ma in Pešek1,a and Ondřej Pech1
1B no Uni e si y o Technology, Facul y o Mechanical Enginee ing, Technická 2896/2, Czech Republic
Abs ac . The a icle deals wi h he ield usabili y de e mina ion o he me hod o measu ing empe a u e
ields in he ai using an in a ed came a. This me hod is based on he isualiza ion o empe a u e ields on an
auxilia y ma e ial, which is inse ed in o he non-iso he mal ai low. In his a icle he ield usabili y is
de e mined om ime cons an s o his me hod, which de ine bo de s o usabili y o low empe a u e
di e ences (be ween ai low empe a u e and su ounding empe a u e) and o low ai low eloci ies. The
ield usabili y de e mina ion o measu ing empe a u e ields in he ai can be used in many a ious
applica ions such as ai -hea ing and ai -condi ioning whe e he me hod o measu ing empe a u e ields in he
ai by in a ed came a can be used.
1 In oduc ion
The empe a u e ield measu emen by he in a ed
came a is e y illus a i e and quick way o measu e he
alue o empe a u e o he empe a u e ield. The
in a ed came a allows o noncon ac measu emen and
i is used o his pu pose in many scien i ic disciplines
and indus ial applica ions, especially in he ield o hea
ans e and he modynamics [1]. The he mog aphy is
mainly used o he su ace empe a u e measu emen s.
The auxilia y ma e ials applica ion o moni o ing
empe a u e ields he ai empe a u e ield is known
a long ime [2]. This measu ing me hod p o ides isual
image eco ds p o iding quali a i e and quan i a i e
in o ma ion o deepe knowledge o he mal condi ions
and he modynamic p ocesses in he esea ch objec . The
in a ed came a allows measu emen s o he s a ic
condi ions and moni o ing o dynamic p ocesses and i is
e y sui able o he usage ou side he labo a o y. The
impo an issue is o de ine he mos sui able ma e ials
ha can be used o moni o ing o he empe a u e
dis ibu ion in he ai using in a ed came a by he
me hod o inse ing a shee o pape o o he auxilia y
ma e ial in o he non-iso he mal ai s eam. This ma e ial
mus ha e sui able s a ic p ope ies, mainly a high
emissi i y. Also, knowledge o he dynamic p ope ies,
especially he knowledge o he ime cons an as
a unc ion o ai empe a u e di e ence and he ai
eloci y is equi ed o p ac ical applica ions o he
me hod. The empe a u e isualiza ion by he in a ed
came a also allows o he deepe unde s anding and
iden i ying o connec ions in he measu ing p ocesses
du ing he moni o ing o a a iable empe a u e ield. The
isualiza ion o empe a u e ields in he ai can also
de ec he spa ial and ime con ex o moni o ed
p ocesses. This me hod o he measu emen o
empe a u e ields in he ai can be used in many ields o
hea ing and cooling [2].
2 The measu ing me hod desc ip ion
The measu emen me hod o empe a u e ields is based
on he usage o he auxilia y ma e ial on which he
empe a u e ields a e displayed. This auxilia y ma e ial
is placed o he ai -s eam o moni o ed a ea [3]. The
con ec i e hea low changes he su ace empe a u e o
auxilia y ma e ial which is measu ed by he in a ed
came a. The conduc ion hea low c ea es he empe a u e
ield on su ace o he auxilia y ma e ial and his su ace
empe a u e can be conside ed as he ai empe a u e o
his a ea.
3 Conduc ion hea ans e
Du ing he isualiza ion o he ai empe a u e ield on
he su ace o he auxilia y ma e ial, conduc ion hea
ans e occu s he dis ibu ion and also he empe a u e
ield sca e ing in he shee o his ma e ial. The hea
ans e by conduc ion is de ined by he Fou ie ´s law as
 = − ∙  , (1)
whe e  (W m-2) is he conduc ion hea lux,
λ (W m-1 K-1) is he hea conduc i i y and g ad T (K m-1)
is he empe a u e g adien .
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 2.0, which pe mi s un es ic ed use, dis ibu ion, and
ep oduc ion in any medium, p o ided he o iginal wo k is p ope ly ci ed.
DOI: 10.1051/
C
Owned by he au ho s, published by EDP Sciences, 2014
, 02091 (2014)
/20146702091
67
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A icle a ailable a h p://www.epj-con e ences.o g o h p://dx.doi.o g/10.1051/epjcon /20146702091
The empe a u e ield sca e ing causes he enla gemen
o he a ea wi h he isualized ai low, and he e o e i
also causes a shi o he ai low bounda y. Conduc ion
hea ans e is no desi ed and is eques ed o be
elimina ed by he use o an auxilia y ma e ial wi h a low
alue o he hea conduc i i y. Un o una ely, he low
alue o hea conduc i i y means e y di icul hea
ans e by con ec ion on he su ace o auxilia y
ma e ial. Low hea conduc i i y causes p oblems wi h
imagining o dynamic p ocesses.
Bo de s enla gemen o he non-iso he mal ai s eam
is possible o de e mine as a solu ion o hea conduc ion
p oblem in a semi-in ini e body. Semi-in ini e body
ep esen s he body whe e exis s a ce ain dis ance x0
om he su ace such ha o all he dis ances x > x0 he
empe a u e T(x, ) equals he ini ial empe a u e
T0(x, = 0) e en hough a change o he empe a u e
occu s a he su ace (x = 0). This means ha he su ace
empe a u e can in luence he empe a u e inside he body
up o he dis ance x om he su ace.
3 Con ec i e hea ans e
Fo he de e mina ion o hea ans e om he ai s eam
o he ma e ial i is necessa y o de ine hea ans e by
con ec ion. The con ec i e hea low  (W m-2) is
de e mined by he New on´s law
 =∙(−
), (2)
whe e  (W m-2 K-1) is he hea ans e coe icien ,  (K)
is su ace empe a u e and  (K) is ee s eam
empe a u e.
Figu e 1. App oxima ion wi h he use o he p opo ional
sys em o he i s o de [4]
The ime cons an  (s) is he quan i y which
cha ac e izes he ime needed o he ansi ional s a e
(caused by an inpu impulse) o a ise o disappea . The
ime cons an is de ined as he ime when 63.2 % o all
inc ease o dec ease alue o moni o ing quan i y is
eached, igu e 1.
4 Measu emen s o he empe a u e ield
sca e ed in he auxilia y ma e ial
The hea conduc ion, which cases he expansion o he
empe a u e ield a ea in he auxilia y ma e ial, was
in es iga ed as well. The assessmen o he conduc ion
hea ans e e ec was pe o med by an expe imen and
also by nume ical simula ion in STAR CCM+ so wa e
p og am. Two ypes o auxilia y ma e ials wi h high
emissi i y alues we e in es iga ed. A common shee o
o ice pape wi h he emissi i y 0.96 and a shee o co on
ex ile wi h he emissi i y 0.93 we e conside ed.
Figu e 2. E alua ion o expe imen he empe a u e ield
sca e ed in a shee o pape a s eady s a e which occu ed a e
10 seconds
Figu e 3. E alua ion o expe imen he empe a u e ield
sca e ed in a co on shee a s eady s a e which occu ed a e
10 seconds
The expe imen al de e mina ion o empe a u e ield
sca e ing was pe o med wi h he use o he he mal p in
wi h known dimensions. Subsequen ly ime cou ses o
expansion o he empe a u e ield in he shee o
auxilia y ma e ial we e eco ded. The objec used as he
he mal p in was selec ed o be a cylinde which was
made om s ainless s eel (s ainless s eel 304) wi h he
diame e d = 50 mm and heigh h = 80 mm.
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The expe imen was pe o med wi h he use o he
in a ed came a Jenop ic Va ioCam. The cylinde was
a ached o he holde and conduc i ely hea ed
o app oxima ely 50 °C. Then he shee o he auxilia y
ma e ial was sho ly p essed a he base o he cylinde
and he in a ed sequence in 60 s was eco ded. The
in a ed eco d e alua ion was ca ied ou in he IRBIS
p o essional so wa e p og am. A e he con ac o he
he mal p in wi h he shee o auxilia y ma e ial i
immedia ely ex ended he empe a u e ield ou side he
edge o he cylinde by he alue o c o he co on shee
o by he alue o p o pape shee . The empe a u e
ield was s abilized a e 10 s o p in ing o he co on
shee and also o he pape shee . Using he command
“ e e ence line” in he IRBIS p o essional so wa e he
size o he empe a u e ield expansion was de e mined.
In case o he co on shee he sca e ing is c = 3.5 mm
and in case o a pape shee p = 3.9 mm. The e alua ions
o hese shee s a e shown in igu e 2 and 3. The sca e ing
size a ea was measu ed om he edge o he he mal p in
o he dis ance whe e he empe a u e ell o 5 % o he
o al empe a u e di e ence.
Table 1. S a ic p ope ies able o auxilia y ma e ials o
de e mine he empe a u e ield sca e ing
Auxilia y
ma e ials
p ope ies
O ice
pape
Co on
ab ic
The mal
p in
mass pe a ea
m, (g m
-2
)
80
145 -
emissi i y
ε, (-)
0.96
0.93
-
densi y
ρ, (kg m
-3
)
750
1550
8000
speci ic hea
capaci y
c, (J kg
-1
K
-
1)
1330
1160
500
hea
conduc i i y
λ, (W m
-1
K
-
1)
0.05
0.029
16.2
The in es iga ed hea conduc ion p oblem in he
auxilia y ma e ial was also in es iga ed by nume ical
simula ions.
Figu e 4. Simpli ied geome y o he model o he
de e mina ion o he empe a u e ield sca e ed in he shee o
auxilia y ma e ial
One o possible simula ion p og ams is STAR CCM+.
This p og am allows o sol e non-s a iona y hea
conduc ion p oblems. The i s s ep was o c ea e he
model geome y. In his geome y model is subsequen ly
applied ma hema ical echniques and physical laws on he
based on de ined bounda ies and ini ial condi ions. The
s a ic p ope ies o auxilia y ma e ials we e used
acco ding o able 1, i.e. he same condi ions as we e in
he expe imen . The simula ion was pe o med on he
simpli ied model, see igu e 4.
The model was c ea ed wi h a 2D polyhed al
compu a ional g id wi h a densi y o 36,000 cells. Due o
a be e desc ip ion o hea ans e in o he shee o
auxilia y ma e ial, he he mal p in posi ion and he
measu ed shee we e equipped wi h a p isma ic bounda y
laye wi h a hickness o 30 cells (4 mm). The a ea whe e
he dis ibu ion o empe a u e ield was expec ed om
he expe imen (10 mm om he wall o cylinde o he
ma e ial), was e ined in o de o achie e a mo e accu a e
desc ip ion o he dis ibu ion o he hea low in o he
auxilia y ma e ial.
A he bo de he bounda y condi ion was se o
“Symme y plane”. The “Symme y plane” bounda y
condi ion does no limi he calcula ion and i will no
in luence he undesi ed hea ene gy accumula ion a he
bo de s o geome y. In he posi ion o he con ac
he mal p in ma e ial, he “in-place” bounda y condi ion
was in oduced, which allows he con ac be ween wo
di e en kinds o ma e ials ( he mal p in and shee o an
auxilia y ma e ial).
The simula ion was sol ed as a non-s a iona y ask
las ing 30 seconds, which leads o wo ma e ial p in s o
di e en empe a u es wi h a cons an densi y. Due o he
ease o calcula ion, he seg ega ed sol e in ol ing
seconda y solid ene gy g adien s was chosen. Du ing he
calcula ion he moni o ing o he esidual ene gy
con e gence le el wi h he accu acy highe han 10-4 was
ca ied ou . The esul o he ma hema ical simula ion
om he simula ion p og am STAR CCM+ is shown in
igu es 5 o shee o o ice pape . Fo he co on shee
he alues c = 3.2 mm was calcula ed and o he pape
shee i was p = 3.8 mm, which is in ag eemen wi h
expe imen s.
Figu e 5. E alua ion o ma hema ical simula ion o he
empe a u e ield sca e ed in a shee o pape a s eady s a e
a e 10 seconds
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5 De e mina ion o ield usabili y
Measu emen s o he ai empe a u e ield using he
in es iga ed me hod is ela i ely accu a e, i hey a e
done in he ield o usabili y o he me hod. The a ea o
ield usabili y is based on limi ing he ange o he
empe a u e di e ence and he ange o he eloci y non-
iso he mal ai low, which depend on he ime cons an o
he me hod. The measu emen accu acy is de e mined by
measu emen unce ain ies [4, 5]. In a eas whe e a high
unce ain y is p oduced, i is no app op ia e o measu e
he empe a u e ield using his me hod.
Figu e 6. 2D iew on he ield o usabili y o he me hod o he
isualiza ion and measu emen o empe a u e ields in ai by
in a ed came a – he o ice pape
Figu e 7. 2D iew on he ield o usabili y o he me hod o he
isualiza ion and measu emen o empe a u e ields in ai by
in a ed came a – he co on shee
The ield o usabili y o he me hod was de e mined
om he dependence on he ime cons an , empe a u e
di e ences and low eloci y o he co on ex ile and o
he o ice pape In hese dependences (Figu e 6 and 7) he
a ea wi h a high ime cons an was supp essed, which
indica es ha he empe a u e ield measu emen using
his me hod is less sui able in hese a eas.
6 Conclusions
The ob ained g aphs o he ime cons an s a e impo an
o c ea ing a me hodology o measu emen s
o empe a u e ields in he ai by he in a ed came a.
The ime cons an s wi h he emissi i y o auxilia y
ma e ial, pa ame e s o in a ed came a and applica ion
limi s o he desc ibed me hod allow o measu emen s
in case o low eloci ies and small empe a u e
di e ences.
The ield o usabili y o he in a ed came a o
measu emen s o he empe a u e ield in he ai is ela ed
o equi emen s, which a e equi ed by applica ions o
measu emen s. In he case he ime cons an o he
me hod is equi ed o be less han 8 seconds, he ield
usabili y can be de e mined om igu e 8 and igu e 9.
These alues o he ime cons an o 8 s a e included
in able 2.
Table 2 Field usabili y o he me hod o isualiza ion and
measu emen o empe a u e ields in ai using an in a ed
came a o he ime cons an less han 8 seconds
Auxilia y ma e ial
Veloci y
Tempe a u e
di e ence
o ice pape
depends on
he
IR
came a
accu acy
depends on he
IR came a
accu acy
co on shee
om
1.2 m s
-1
om 6 K
In assessing o he ield usabili y o he me hod i is
necessa y o conside he in luence o hea conduc ion in
he auxilia y ma e ial. This can cause some "blu " e ec s
which is usually no possible o iden i y in non-
iso he mal ai s eams. This e ec needs o be especially
conside ed in a eas wi h la ge empe a u e g adien s, e.g.
in he mal limi laye s.
Acknowledgemen s
The esea ch leading o he p esen ed esul s was
suppo ed by he NETME Cen e ED0002/01/01 and
B no Uni e si y o Technology p ojec FSI-J-13-2042 o
young esea che s.
Re e ences
1. M. Vollme , K.-S. Mollmann, In a ed The mal
Imaging: Fundamen als, Resea ch and Applica ions,
Wiley (2010)
2. M. Pešek, M. Pa elek, Se kání ka ede mechaniky
eku in a e momechaniky, Mikulo (2010)
3. M. Pešek, M. Pa elek, Expe imen al luid
mechanics, Jičín (2011)
4. T. O zechowski, Ł.J. O man, Science Repo (2006)
5. T. O zechowski, Ł.J. O man, Pollu ion Enginee ing
(2006)
Veloci y low (m∙s-1)
Time cons an (s)
Tempe a u e di e ence (T)
Time cons an (s)
Tempe a u e di e ence (T)
Veloci y low (m∙s-1)
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