Heat Transfer Laboratory
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EXPERIMENT NO. 4
((The effect of varying flow rate-parallel flow double pipe heat exchanger))
Aim:
To show how different cold flow rates affect the performance of the heat exchanger in parallel
flow connection.
1. Theory & procedure
1.1 Heat transfer, energy balance and efficiency
In heat exchangers, heat transfers or flows from the hot water circuit to the cold-water circuit. The
heat transfer rate is a function of the fluid mass flow rate, the temperature change and the specific
heat capacity of the fluid (at mean temperature).
m Cp ΔT (1)
In an ideal heat exchanger, that does not lose or absorb heat from its surroundings, the cool fluid
absorbs all the heat from the hot fluid [1-4]
. So, the heat transfer rate is:
= mH CpH ΔTH = mc Cpc ΔTc (2)
Fig. 1 Parallel flow scheme

Heat Transfer Laboratory
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Table 1 Notation

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Fig. 2 Specific heat capacity of water at constant pressure [1]
Fig. 3 Water density [1]

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2. Reading table & calculation Table 2 Reading table
10 L.min-1
= 0.0001667 m3
.s-1
∆TH = TH1 - TH2 (3)
∆TC = TC2 - TC1 (4)
Mean heat transfer area = 0.02 m2
Overall heat transfer coefficient:
(5)
Temperature efficiency:
(6)
(7)
(8)
(9)
(10)
(11)

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3. Discussion questions
a) Why we get different mean temperature efficiency?
b) Draw a simple temperature chart for each condition.
c) Discuss the effects of the flow rate on the rate of heat transfer.
d) Why we have errors?
Fig. 4 Double pipe – Parallel flow heat exchanger apparatus [1]
References
1. TecQuipment Ltd, Concentric tube heat exchanger apparatus, Model: VDAS-F TD360A.
2. Мохамед Б, Кароли Я, Зеленцов А.А. (2020) Трехмерное моделирование течения газа
во впускной системе автомобиля «формулы студент» Журнал Сибирского
федерального университета, 13(5); pp. 597-610. https://doi.org/10.17516/1999-494X-
0249.
3. Mohamad B., Karoly J., Zelentsov A.A. (2020) Hangtompító akusztikai tervezése hibrid
módszerrel, Multidiszciplináris Tudományok, 9(4), pp. 548-555.
https://doi.org/10.35925/j.multi.2019.4.58.
4. Yunus Cengel, Heat Transfer: A Practical Approach, 2nd
ed., McGraw-Hill Education –
Europe, 1997.
Barhm Abdullah Mohamad
Erbil Polytechnic University
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