DETERMINATION OF NEEDED PARAMETERS FOR MEASURING
TEMPERATURE FIELDS IN AIR BY THERMOGRAPHY
Ma in PEŠEKx, Milan PAVELEKxx
Abs ac : The aim o his a icle is he pa ame e s de e mina ion o equipmen
o measu ing empe a u e ields in ai using an in a ed came a. This me hod
is based on he isualiza ion o empe a u e ields in an auxilia y ma e ial, which
is inse ed in o he non-iso he mal ai low. The accu acy o ai empe a u e
measu emen (o o su ace empe a u e o supplies) by his me hod depends
especially on (excep o pa ame e s o in a ed came a) he de e mina ion
o he s a ic and he dynamic quali ies o auxilia y ma e ial. The emissi i y
o suppo ma e ial is he s a ic quali y and he dynamic quali y is ime cons an .
Suppo ma e ials wi h a high emissi i y and a low ime cons an a e sui able
o he measu emen . The high alue o emissi i y esul s in a highe
measu emen sensi i i y and he adia ion empe a u e independence.
In his a icle he emissi i y o examined kinds o auxilia y ma e ials (pape s
and ex iles) is de e mined by empe a u e measu ing o hea ed samples
by a calib a ed he mocouple and by he mog aphy, wi h he emissi i y se ing
on he came a o 1 and wi h he homogeneous adia ion empe a u e. Time
cons an s a e de e mined by a s ep change o ai empe a u e in he su ounding
o auxilia y ma e ial. The ime cons an depends mainly on hea ans e
by he con ec ion om he ai in o he auxilia y ma e ial. Tha is why he e ec
o ai empe a u e is examined in his a icle (o a empe a u e di e ence owa ds
he en i onmen al empe a u e) and he low eloci y on he ime cons an
wi h a ious ypes o auxilia y ma e ials. The ob ained esul s allow o de ine
he condi ions o using he me hod o measu emen o empe a u e ields in ai
du ing a ious hea ing and ai condi ioning applica ions.
1. INTRODUCTION
In a ed came a is a e y e ec i e de ice o a noncon ac measu emen
o empe a u e ields in many scien i ic disciplines. This measu ing me hod p o ides
a isual image eco ds, allowing quali a i e and quan i a i e in o ma ion o a deepe
knowledge o he mal condi ions and he he modynamic p ocesses in he esea ch
objec . The he mog aphy is being used mainly o de e mining su ace empe a u es,
x Ing., Ene gy Ins i u e, Facul y o Mechanical Enginee ing, B no UT, Technická 2896/2, B no, el.
(+420) 541 143 241, e-mail [email p o ec ed]
xx P o . Ing. CSc., Ene gy Ins i u e, Facul y o Mechanical Enginee ing, B no UT, Technická 2896/2,
B no, el. (+420) 541 143 272, e-mail [email p o ec ed]
EPJ Web o Con e ences , 010 (2012)
DOI: 10.1051/epjcon /201225010
© Owned by he au ho s, published by EDP Sciences, 2012
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
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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 /20122501069
bu his a icle ies o ex end he possibili ies o moni o ing and measu emen
o empe a u e ields in he ai .
Immedia e knowledge o he dis ibu ion o empe a u e ield in he noniso he mal
ai low can allow o quickly iden i ying a possible p oblem such as he design o ai
condi ioning o ho -ai hea ing. 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.
Conce ning he ac ha he ai is ansmissi e, i is necessa y o de e mine he
empe a u e in he noniso he mal ai s eam by using sui able auxilia y ma e ial o
isibili y o empe a u e ields. The impo an ac o is o de ine he mos sui able
ma e ials ha can be used o moni o ing he empe a u e dis ibu ion in he ai using
he mo ision came a by he me hod o inse ing shee s o pape o o he auxilia y
ma e ial in o noniso he mal ai s eam. This ma e ial mus ha e sui able s a ic p ope ies,
mainly high emissi i y. Also, o p ac ical applica ion o ha me hod o
measu ing empe a u e ields o knowledge o he dynamic p ope ies, especially he
knowledge o he ime cons an as unc ion o ai empe a u e di e ence and he ai
eloci y equi ed.
2. EMISSIVITY
The emissi i y is one o he basic s a ic p ope ies o auxilia y ma e ial
a measu emen s o empe a u e ields in he ai by he mog aphy. Ma e ials
o he mo ision measu emen s o ai empe a u es should ha e especially high
emissi i y  [-] in o de o maximize he accu acy and o nonin luence o high ambien
adia ion empe a u e [K]. Emissi i y has also an in luence on he de e mina ion
o ime cons an o his measu emen me hod. By sea ching o sui able ma e ial di e en
ypes o pape s and ab ics we e compa ed. An emissi i y measu emen o he s udied
ma e ials was pe o med in he labo a o y wi h a homogeneous adia ion empe a u e.
The adia ion ambien empe a u e was de e mined by he adia ion he mome e Tes o
830-T2, as he a i hme ic a e age o adia ion empe a u e o su ounding su aces
(walls, ceiling and loo ).
Figu e 1: Emissi i y measu emen
o suppo ma e ial
Figu e 2: The mog am o he emissi i y
measu emen s
THERMOCOUPLE
SENSOR
MEASURING BY
THERMOVISION
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The emissi i y o he s udied ma e ials was measu ed on samples hea ed
in he coole en i onmen by he sample empe a u e om 40 °C o 80 °C. In case he
samples we e hea ed a highe empe a u e, i could lead o deg ada ion o ma e ial
p ope ies and he high ai empe a u e wa m ai hea ing sys em don´ co espond wi h
he quali y o indoo en i onmen [1]. In he o he case when he samples we e hea ed
lowe han 40 °C, su icien empe a u e di e ence be ween su ounding en i onmen ,
adia ion empe a u e and he ma e ial´s empe a u e shouldn´ be gi en.
Such case would lead o an inc ease o measu emen unce ain ies. This
empe a u e di e ence should be a leas 25 K wa me in he measu emen o samples in
a coole en i onmen and in he opposi e op ion a leas 15 K [2].
Measu emen s we e pe o med by he he mo ision came a Jenop ik,
ype Va ioCam ha has he spec al sensi i i y om 8 o 13 μm wi h he esolu ion
o 320 x 240 pixels and wi h he scanning equency o 50 ames pe second.
The s udied ma e ial was ixed o a hick s eel pla e wi h an adhesi e ha didn´ change
p ope ies o he ma e ial on he su ace. On he pla e calib a ed he mocouple was
placed, which measu ed he ac ual empe a u e. Then he pla e was hea ed up o
app oxima ely 85 °C and i was placed in he ack be o e he he mo ision came a wi h
se up a he igh angle o he di ec ion o obse a ion by he he mo ision came a
(Figu e 1).
Fo e alua ion he emissi i y o ma e ial, he empe a u e TC [K] was de e mined
om he mog am (wi h se ing he mo ision came a o emissi i y o alue 1),
he sample su ace empe a u e TT [K] was measu ed by he mocouples
and he adia ion ambien empe a u e TR [K] was de e mined by he adia ion
he mome e . As a e e ence empe a u e eadings we e aken om he he mocouple
TT [K]. Tempe a u e eadings we e held a in e als o 5 K om he empe a u e o 80 °C
o 40 °C. The inal emissi i y o ma e ial is gi en by he ela ionship [2]
(1)
whe e n [-] is he exponen in he selec ed, sui able o he wa eleng h ange o
he mo ision came a Va ioCam and o empe a u e ange in es iga ed.
The ype o auxilia y ma e ial Weigh [g/m2]  [-]
Plain o ice pape 80 0,96
Ca dboa d d awing 180 0,93
Pape s
T acing pape 75 0,91
Co on ex ile 145 0,93
Elas ic ma e ial 70 % Co on, 30 % Lyc a 130 0,90
Denim 270 0,81
Tex iles
Table linen – 100 % polyes e 195 0,67
Figu e 3: Emissi i y alues o auxilia y ma e ial
Fo each measu emen he adia ion empe a u e o su ounding en i onmen
was ead by he adia ion he mome e and he mean alue was de e mined. The inal
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mean emissi i y o he ma e ial was calcula ed acco ding o (1) in he empe a u e ange
om 80 °C o 40 °C and de e mined as he a i hme ic a e age o he measu ed
emissi i y a 5 K in e als. Moni o ed samples o ma e ials a e gi en in he able
(Figu e 3), whe e he e a e auxilia y ma e ials wi h highe emissi i y alues. To
de e mine he ime cons an 0 [s]by his me hod, a plain o ice pape and co on ex ile
was chosen.
3. TIME CONSTANT
Shee o he auxilia y ma e ial (co on ex ile and pape wi h he highes
emissi i y) was ixed o he sliding s and abo e he hea sou ce (di e en ypes o ho -ai
ans) and he he mo ision sequence was scanned wi h di e en empe a u es and an
speeds wi h a s ep change posi ion o he auxilia y shee . In a ed he mo ision
sequences we e scanned by he came a Jenop ik ype Va ioCam. Pho os
om he measu emen s a e shown in he igu e (Figu e 4).
Figu e 4: Pho og aphy and he mog am he ime cons an de e mina ion
On he base o heo e ical analysis and he measu ed alues i can be assumed
ha his is a sys em wi h one ime cons an 0 [s]. This cons an can be de e mined
om his equa ion:
(2)
whe e
>@
Cq is he s eady alue o su ace empe a u e o he auxilia y ma e ial
and
>@
Cq is he su ounding empe a u e. This ime cons an is a unc ion o ai
eloci y and he empe a u e di e ence o noniso he mal ai low due o he su ounding
empe a u e. I was also necessa y o measu e he eloci y and he empe a u e ields
wi h esis ance- ype anemome e Tes o 491 and he mocouples in o de o compa e
he ime cons an o di e en eloci ies and empe a u e di e ences. In a ed sequences
we e e alua ed in he p og am IRBIS P o essional 2.2. Imaging o s ep changes
we e pe o med wi h a equency o 50 ames pe second o 10 minu es ( o he su ace
empe a u e was s abilized). Time cons an s in each o measu emen poin s
we e subsequen ly de e mined by he equa ion (2). In he igu e he dependence o ime
cons an his me hod is gi en on ai low speeds and empe a u e di e ences
o he co on ex ile.
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The ime cons an 0 [s], which is lowes wi h highes empe a u e di e ence
T [K] and wi h highes eloci y w [m/s] is shown in igu e (Figu e 5).
4. CONCLUSION
Among he examined ma e ials he bes p ope ies ha e plain o ice pape
o explo ing he empe a u e dis ibu ion in he noniso he mal ai s eam. I has
he highes emissi i y. O he ypes o pape s ha e lowe emissi i y alues
and he measu emen is di icul due o hei mechanical p ope ies. The ab ic can be
well s o ed and mobile, bu i s p ope ies o measu ing o empe a u e ields
by he in a ed came a in ai a e less sui able o he lowe emissi i y compa ed o o ice
pape .
Calcula ed alues o he ime cons an s a e impo an o c ea ing a me hodology
o measu ing o empe a u e ields in he ai by he in a ed came a. Time cons an s
oge he wi h auxilia y ma e ial emissi i y and pa icula pa ame e s o in a ed came a
in o de o de ine he bounda ies applica ion o his me hod by low eloci ies and small
empe a u e di e ences.
Figu e 5: Dependence o ime cons an s, ai low speeds and empe a u e
di e ences o he co on ex ile 145 g/m2
5. ACKNOWLEDGEMENT
The suppo o his esea ch om Czech Science Founda ion p ojec no.
GA 101/09/H050 “Resea ch in o ene gy-sa ing de ices o achie e com o o he in e nal
en i onmen “ and he s anda d p ojec FSI-S-11-6 “Human Cen e ed Design”
is g a e ully acknowledged.
6. REFERENCES
[1] SN EN ISO 7730.: Mí né epelné p os edí. S ano ení ukaza el PMV a PPD
a popis podmínek epelné pohody. P aha. eský no malizaní ins i u , 1997.
[2] Pa elek, M.; Jano ko á, E.: Rozbo pa ame  o li ujících zmny po cho ých
eplo s a ebních kons ukcí budo . S ojá s o/S ojí ens í. 2009, No.
mimo iadne, s. 197-200, ISSN 1335-2938
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