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Transcript of jishnu COPY
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WELCOME
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EXPERIMENTAL STUDIES OF A DOUPIPE HELICAL HEAT EXCHANGE
Guided By :
AJAI M
ASST.PROFESSOR
Dept. of ME
MCET
Presented By :
JISHNU
S7 ME
Roll No
MCET
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INTRODUCTION
Helically coiled tubes are superior to straight tubes
Development of secondary flows due to centrifugal force enh
heat transfer
Two major boundary conditions: constant wall temperature a
constant heat flux
The outer wall of the annulus will be insulated
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Poor circulation of fluid could be avoided using a double pip
configuration
The temperature of the inner wall of the annulus will be dict
by the fluid temperature in the inner tube
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OBJECTIVE
Design, build and instrument two double-pipe helical heat ex
The difference between the two being the size of the inner tu
Experimentally evaluate the heat transfer characteristics of a
pipe helical heat exchanger for both parallel flow and counte
configurations
Compare the experimental results
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MATERIALS AND METHODS
Heat exchanger
Constructed from copper tubing
Outer tube of heat exchanger had an outer dia of 15.9mm
Wall thickness of 0.8mm
Inner tube had an outer dia of either 9.5mm or 6.4mm
Each coil had a radius of curvature of 235.9mm
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EXPERIMENTAL APPARATUS
Cold tap water is used for the fluid flowing in the annulus
A large reservoir and a submersible pump was used to flow t
annulus
Flow was controlled by a flow meter with an attached meteri
Hot water for the inner tube was set at 60 degree Celsius
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EXPERIMENTAL APPARAUS(CONTIN
Flow rate of inner tube was controlled by an identical flow m
metering valve
Flexible PVC tubing was used for all connections
Type k thermocouples are used to measure the inlet and outle
temperatures for both fluid
Temperature data was recorded using a data acquisition conn
computer
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EXPERIMENTAL PROCEDURE
Flow rate in the annulus and in the inner tube were varied
Following five levels were used: 100, 300, 500, 700, 900cm
These were done for both coils and in parallel flow and coun
configurations
Three replicates were done for every combination of flow ra
size and configuration
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CALCULATION OF HEAT TRANSFCOEFFICIENTS
Overall heat transfer coefficient was calculated from the tem
data
Heat transfer coefficients for the annulus and for the inner tu
calculated using traditional Wilson plots
Method was chosen to avoid the disturbance of flow patterns
transfer while attempting to measure wall temperatures
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Generated by calculating overall heat transfer coefficients w
fluid kept constant and other varied
Flow in the inner tube was kept constant and the flow in the
was varied for the five different flow rates.
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CALCULATION OF HEAT TRANSFCOEFFICIENTS
Uo = Overall heat transfer coefficient
Q = Heat transfer rate
Ao = Surface area
LMTD = Log mean temperature difference
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RESULTS AND DISCUSSION
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CONCLUSION
Little difference between the overall heat transfer coefficient
parallel flow and counter flow configurations.
Heat transfer rates were much higher in the counter flow con
due to the larger average temperature difference between the
fluids.
Nussult number in the annulus was compared to the numeric
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REFERENCE
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THANK YOU
QUESTIONS ???