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TECF{-EB
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TECH"EF
Aim:-
To find out total thennal resistance and total thermal conductivityiffcomposite slab
Description:-
The apparatus consists of central heater sandwiched between two sheets,
These Upes of slab provided on both sides of heater, which folms composite
structure. A srnali hand press is provided to ensure perfect contact between
the slabs. A dimmer stat is provided to vary heat input of heaters and it ismeasuled by a digital voit meter and atnmeter. Thertlocouples are
embedded between interfaces of slabs. A digital temperature indicator is
plovided to measure temperature at various points.
Specification:-
1. Slab assernbly arranged symmetrically on both sides of the s1ab.
2. I'Jichrome heater wound on mica heater of 30O-Watt capacitSz.
3. Dimmer stat open type, 230v,0-2 anp, single phase'
4. \/olt rneter5. Ammetet'6. Digital temperature indicator 0-2000 C7. Enclosule size : 300x300x300 rnm8. Slab diameter:300 mtl.9. Thickness of cast iron : 25tnrn.l0.Thickness of Bakelite:19 mm.1 l.Thickness of wood: 12 rrrm.
TE,CH-EB
Procedure:-
Arrahge the plates in proper fashion on both sides of heater plates.
rtact between plates.
2. Close the box by cover sheet to achieve proper environmentalcondition
.,.3. Starl the rnain switch.4. By adjusting the dimmer knob give heat input to heater. (Say B0V,
90V etc.)5. Take the readings of all (8) thennocouples at an interval of i0 rnin.
Until the final steady state.6. Note down the reading in observation table.7. Make dirlrrrer knob to "zero" position and then put main switch off.8. Repeat the procedure for diffelent heat input.
Otiservation Table:-
Formulae:-
i. Heat input
Q: VxI .'...'.'Watts2
2. TA avg : Ti + T2 ....oC1
TB avg : T3 + T4 ....oC2
TC avg : T5 + T6.. ..oC2
sl.No,
\/Volts
Iamps
T1oc
T2oc
T3oc
T4oc
T5oc
T6oc
T7oc
T8oc
fo, c"t(c.-f..{,.? jr: tb T ,.*f-s- rrc t qft= *,o, *lt" yr,a,W t_-,=_:f- {b* ft7 *ilretVa, &-4*a( (**'o.4. Tlremal Resistance of Slab ( R ) fc LrrtitliTr,r4td"*f +C'*-f-
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TD avg : T7+ T8 ....oC2
.3. Alea of Slab
A: JI d24
Where "d" is diameter of slab. (Effective dia.
5. Thelrnal Conductivity ( K )
K: Oxt.... Wlm kA (TA avg - TD avg )
Where "t" is thickness of slab.
TECH-ED
: 300 mm)
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Precautions:-
i) Keep the dim're'stat to zero before starti'g the experiraent.ii) while removing plates do not dist'r-b trreriiocoupies.
Use the selector su'itch knob and dimmer icnob gently.
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