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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 ???

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