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Method Of Approach
Apparatus
The figure is a diagram of the two flow loops, which exchange energy through the heat exchanger. Hot water
circulates through the exchanger shell while cold water circulates through the tubes. A pump drives the hot water
flow, while the cold water flow comes from the building water supply. Only the cold flows is controlled manually by
a knob. Mass flow rates are indicated by flow meters. Four thermocouples were mounted close to the four ports of the
heat exchanger and connected to a computer for a digital reading that would indicate Thin, Thout,
Tsin, Tcout
to see the set up click here
Procedure
- Set the Cold Water flow meter at the lowest reading and monitor the difference between the inlet
and outlet temperatures for both cold water and hot water until a steady state is established
(usually in a few minutes).
- Measure and record the inlet, outlet and temperature difference for both water flows.
- Change the cold water flow to give C = .75, then .5 and .25, each time repeating 1 and 2 above.
- Sequence through all the possible experimental configurations changing one variable at a time.
- Plot the heat transfer to the hot water vs. the log-mean-temperature difference.
- From the experiments performed, determine the average overall heat transfer coefficient, U,
from the following definition:
Heat Transfer = ( Cp)h
Th = U A TLMTD
Note that the slope of the curve plotted in 5 is equal to UA.
- On one plot, plot the effectiveness,
 , versus NTU
and curve fit the data where C is a constant using eq. (15).
from the data is determined from the four measured temperatures using eq. (16).
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