HEAT TRANSFER LAB Presentation

Jadavpur UniversityPower Engineering Dept

** PRASUN CHOWDHURY (000911501001)

**KISHORE MANDI (000911501002)

**SUBEDIT DAS (000911501005)

Created by :

TOPIC :

To determine the thermal conductivity of insulation for a LAGGED PIPE.

INTRODUCTIONLagging of pipes is required to prevent

LEAKAGES of heat. The apparatus is designed to study the lagging phenomenon. In Lagged Pipe apparatus, three concentric pipes are arranged between two supports.The gap between the pipes are filled compactly by two different insulating materials and heater is provided at the centre of inner pipe. Temperature at various points are measured with thermocouples. Heat input is measured by voltmeter and ammeter readngs.

APPARATUS USEDvoltmeter ammeter

Temperature indicator

knob

SECTIONAL VIEW OF THE APPARATUS

ASSUMPTIONS

There is no heat loss from the two ends of the pipe.

No heat lossoo

Insulations preventing the

heat to come out axially

There is one dimensional radial heat conduction through the insulator.

The other assumptions are:

We assume steady state heat conduction.

We have to assume the length of the pipe and the length of the heater to be the same.

OBSERVATION TABLE

Run No.

Voltage

(V)

Current (I)

Ta (K)

R1=25

Tb (K)

R2=38

Tc (K)

R3=50

Td (K)

R4=62

1 40 0.18

62.7

41.3

35.7

26

2 50 0.22

74 46.7

38.7

28

3 70 0.31

102

59.3

47.7

31

CALCULATIONS(experimental)

The rate of heat generation is given by q@=Vi…….(1)Where V=applied voltage i=current through the heaterAt the steady state condition, the above heat is dissipated radially.From the governing equation of heat transfer by conduction we get q@=-kA(dT/dr)Now A=2πrL, So q@=-k(2πrL)dT/dr……………………(2)So equating (1) and (2) we get the following equationk=Vi/(2πrLdT/dr)This is the value of k obtained experimentally.

CALCULATIONS(theoretical)

T1 -T12 are the temperatures of 12 thermocouples.

Ta=(T1 + T2 + T3 )/3

Tb=(T4 + T5 + T6)/3

Tc=(T7 + T8 + T9 )/3

Td=(T10 + T11 + T12 )/3The theoretical working equation is q@=( Ta - Td)/[ln(R4/R1)/2πkL]where k=thermal conductivity L=length of the pipek= q@ ln(R4/R1)/ [2πL(Ta - Td)]This is the value of k obtained theoretically.

RESULTSRUN no.

Ktheo(W/mK)

Kexpt(W/(mK)

% Error

1 0.244 0.298 18

2 0.25 0.36 38

3 0.31 0.45 32

Temperature vs Radial length graph

25 38 50 620

50

100

150

200

250

300

t3t2t1

ACKNOWLEDGEMENT

We are very much grateful to the following teachers,without them this expt would not have been possible.

Prof. Amitava DuttaProf. A. K. SatraSri Bireshwar PaulSri Atish Nandi

THANK YOU