Heat Transfer In Turbulent Flow Lab CL 232 Expt. No. HT-208 - - PowerPoint PPT Presentation
Heat Transfer In Turbulent Flow Lab CL 232 Expt. No. HT-208 Department of Chemical Engineering Indian Institute of Technology Bombay Heat Transfer in Turbulent Flow 17/01/2013 1 Associated People Faculty Members: Prof.
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Department of Chemical Engineering Indian Institute of Technology Bombay
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Faculty Members:
List of TAs :
Lab Staff Members:
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To determine the overall heat transfer coefficient making use of
logarithmic mean temperature difference (LMTD).
To determine the individual film heat transfer coefficients and
verify Dittus-Boelter equation for turbulent flow heat transfer.
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Overall resistance = sum of resistances in series Dittus-Boelter equation Final equation Plot (Wilson plot)
i i A
h 1
lm
KA x ∆
h 1
i i i i
A h KA x A h A U 1 1 1 + ∆ + =
lm i i i
A h A KA xA h U + ∆ + = 1 1
( ) ( )
3 . 8 .
Pr Re 023 . = Nu
( )
8 .
* velocity const Nu =
2 8 . 1
1 1 const u const Ui + =
8 .
1 1 u vs Ui
(Hot) (Cold)
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Flow meter Digital display of temperature Double pipe heat exchanger
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1)
Switch on the temperature indicator and controller. Check the set point of the controller. The set point will be around 65 to 700 C.
2)
Start the hot fluid circulation pump. Initially keep the flow rate at low speed by a regulator. Note down the temp difference between inlet and outlet temperatures, which gives zero error. After noting down the zero error, switch on the heater.
3)
Keep the cold fluid flow rate at 240 lph. Keep this flow rate constant throughout the experiment.
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4)
Adjust the hot fluid flow rate by regulator (the minimum flow rate of hot fluid should be at least 40 cc/s, or 144 lph to maintain Reynold's number above 10000 in the heat exchanger).
5)
Note down the inlet and outlet temperatures of hot and cold fluid after steady state is reached.
6)
Repeat step 4 & 5 for at least 6 different flow rates of hot fluid.
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No of Obs Hot fluid flow rate (lph) Hot fluid temperature (0C) Cold fluid temperature (0C) Inlet (T1) Outlet (T2) Inlet (t1) Outlet (t2) 1 2 3 4 5 6
temperature (650C).
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1.
Cross-sectional area of inner tube:
2.
Inside heat transfer area of heat exchanger:
3.
Prandtl number of hot fluid at mean temperature:
4.
Velocity of hot fluid through heat exchanger:
5.
Amount of heat transferred:
6.
Logarithmic mean temperature difference (∆Tlm):
2 1
4 d S π = L d A
1
π =
K C p µ = Pr S V u =
( )
2 1
* * * T T C V Q
p
− = ρ
( ) ( ) ( ) ( )
1 2 2 1 1 2 2 1
ln t T t T t T t T LMTD − − − − − =
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7.
Overall heat transfer coefficient:
8.
Plot ; and calculate outside film heat transfer coefficient (ho) from the intercept.
9.
Inside film heat transfer coefficient:
lm
T A Q U ∆ =
8 .
1 1 u vs Ui
− =
i
h U h 1 1 1
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