The document outlines an experiment conducted at Koya University focusing on a double pipe heat exchanger using a counter-current flow method, aimed at determining heat loss. It describes the theory, procedure, data collection, calculations, and discussions related to the efficiency of counter-current versus co-current heat exchangers. The experiment resulted in a recorded heat loss of 1.307504 J/s through the process, emphasizing the higher efficiency of the counter-current flow arrangement.

1. Experiment: Double pipe heat exchanger
1
Koya University Faculty of Engineering
Chemical Engineering Department
Third Stage
Heat transfer Laboratory
Double-pipe heat exchanger: counter-current flow
2023-2024
Prepared by: supervised by:
Dima Jawhar Mr. Mabast Qadr
Sntia louay Mr. Soran Dlawar
Hunar Hamdi
Amirjan Shawkat
Ara Fakher Qadr
Huda Jihangeer
Hana kamal
experiment date: Nov./29/2023 Submitting date: Dec./6/2023
Report date: Nov./29/2023

2. Experiment: Double pipe heat exchanger
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Table of Contents
Aim: .........................................................................................................................................3
Theory:.....................................................................................................................................3
Procedure: ................................................................................................................................4
Calculations:.............................................................................................................................7
Discussion:...............................................................................................................................8
References:.............................................................................................................................14

3. Experiment: Double pipe heat exchanger
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Aim:
To determine the heat loss in a double pipe heat exchanger counter-current flow
experiment.
Theory:
A double-pipe heat transfer exchanger consists of one or more pipes placed
concentrically inside another pipe of a larger diameter with appropriate fittings to direct
the flow from one section to the next. One fluid flows through the inner pipe (tube side)
in this experiment (hot water), and the other flows through the annular space (annulus)
(cold water).
The double-pipe heat exchanger is one of the basic kinds of exchangers with a very
flexible configuration. There are two types of counterflow or parallel flow for this type
that are the basis of design and calculation for determining pipe size, length, and
number of bends.
Double pipe heat exchanger counter current: heat is exchanged between two flowing
fluids at a different temperature that flows counter current in the heat exchanger double
pipe.
The efficiency is greater in counter-current than in parallel flow because the two fluids
(water) flow separately in counter-current flow when the high different temperatures
meet heat exchange rapidly due to the difference of temperatures, the hot water
becomes warm then cold as heat exchanges, and the cold water becomes warm the heat
exchange occurs till it reaches steady state. As it is explained in Figure 1.
Heat loss can be found by the equation below:
Q=ΔH=mCpΔT
Where: Q=ΔH is the amount of heat transferred to or from the system (J).
m: mass of the system (Kg)
Cp: constant pressure specific heat capacity of the system (J/g°C)
ΔT: difference in temperature of the system °C.

4. Experiment: Double pipe heat exchanger
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Figure 1: concurrent and countercurrent respectively.
Procedure:
Double pipe heat exchanger: as shown in the figure-2:
1. Power switch: No.1
2. Temperature scale to select a temperature to heat the water in the tank [No.2] in
the figure.
3. Water tank a heating coil is used to heat the water [no.3].
4. Power pump to set a flow rate, the water is pumped through the double pipe heat
exchanger. [No.4]
5. A flow rate measurement is found in no.5
6. [No.6-7-8-9-10] The temperature measurements measure temperature
throughout the process.
7. Then the temperature and flow rate are collected in the temperature screen.

5. Experiment: Double pipe heat exchanger
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Figure 2: double pipe heat exchanger.

6. Experiment: Double pipe heat exchanger
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observation:
1. Turn on the device with the power switch.
2. The flow rate is set as 157 ml/s.
3. Heat water up to [40-50 Celsius] in this experiment: [44.4 Celsius] by the
heating coil in the water tank, set the desired temperature by the temperature
scale in the water tank.
4. Then water is pumped to the pipes by the power pump.
5. Adjust the valves so that the hot water and cold water flow countercurrent.
6. The hot water flows in the inner pipe in the double pipe through the pipe from
the pump to the heat exchanger
7. the cold water flows in the outer pipe counter current from the tank to the pipes
the valves are set so that it flows counter current.
8. Data is collected when the heat exchange is done.
Data collected:
Temperature.1:
[Celsius]
Temperature.2:
[Celsius]
Temperature.3:
[Celsius]
Flowrate:
[L/hr]
Hot
water
44.4 41.1 37.6 157
Cold
water
13.1 17.6 22.7 139

7. Experiment: Double pipe heat exchanger
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Calculations:
Heat loss for (hot water):
Q=ΔH=mCpΔT
V=157 L/hr= 0.0436 kg/sec
T= T2 – T1 = 44.4 – 37.6 = 6.8 o
C
T (avg) =
𝑻𝟏+𝑻𝟐+𝑻𝟑
𝟑
=
𝟒𝟒.𝟒+𝟒𝟏.𝟏+𝟑𝟕.𝟔
𝟑
= 𝟒𝟏. 𝟎𝟑 o
C
Cp of water at T (avg) = 41.03 o
C Cp= 4.18 kJ/(kg⋅o
C)
Q = mCpΔT = 0.0436 * 4.18 * 6.8 = 1.307504 J/s
Q=1.307504 J/s was lost in the heat exchange process.
Counter current double pipe heat exchanger chart:
0
5
10
15
20
25
30
35
40
45
50
0 0.5 1 1.5 2 2.5 3 3.5
countercurrent
Hot water cold water

8. Experiment: Double pipe heat exchanger
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Discussions:
Name: Dima Jawhar
1. Compare counter current heat exchange to concurrent flow heat exchange:
Heat is more lost in counter-current because it has a higher efficiency due to the
different directions of the two fluids in the double pipe, the high difference in
temperatures makes the heat exchange faster than the uni-flow heat exchange.
But in co-current the two fluids (water) cold and hot flow parallel to each other in the
double pipe thus the heat exchanges as the fluid's temperature (heat) increases slowing
because of this it has a lower efficiency.
Note that the two fluids never combine and are separate only heat exchanges.
2. Discuss the counter-current chart:
As shown in the chart because they flow in different directions the hot water
temperature decalins in the process indicate that heat is lost but the cold water
temperature rises fast and the curve shows the hot water decalins and the cold water
rises.
during the process continuously the cold and hot water temperatures change till it
becomes constant thus it means the process reaches a steady state.
3. Compare the counter-current chart with the co-current chart.
referred to the counter-current chart it’s noted that there is a higher heat
exchange since the lines decline or decrease with a larger slope.
The graph of uniflow shows that the heat exchanges slowly till it reaches a
steady state when the two lines go parallel.
However, the co-current chart in the other experiment is recalled in Figure 1.
Note that in the parallel flow configuration, the cold outlet can never be warmer
than the hot outlet. Just as the hot outlet can never be cooler than the cold
outlet. Conversely, both scenarios can occur in the counterflow configuration,
as shown in the illustration.
4. Explain the errors in the experiment:
• Human error in recording data
• Setting a different flow rate very high or too low, to compare the two
types of heat exchangers the flow rates should be the same.
• Error on setting the water temperature too high or too low.
• Select which valve to close or open to make sure which process of heat
exchange is done.
5. Explain why in this experiment the counter-current chart looks similar to
the co-current but not as the standard chart shown in Figure 1.
Because heat exchanges continuously in the experiment there might have been
errors in collecting data.

9. Experiment: Double pipe heat exchanger
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Name: Amirjan Shawkat
1. Which flow arrangement is more efficient in double-pipe heat exchangers?
Explain the reason.
Counterflow arrangement is generally more efficient in a double-pipe heat
exchanger. Because in counterflow, the hot and cold fluids flow in opposite
directions, allowing for a larger temperature difference along the length of the
pipes in the exchanger. This maximizes the overall heat transfer and results in a
more efficient heat exchange process compared to parallel flow.
2. Explain any potential errors that could arise during the experiment.
ambient conditions: slight variations in temperature and pressure could lead to
inconsistent measurements since heat transfer is a function of temperature
difference.
Conditions inside the heat exchanger itself: no flow is ideal, meaning there’s
always minimal pressure variations due to the changes in velocity of the water,
this leads to minimal to significant errors when measuring the heat loss from
the hot water. The reason for this is that enthalpy change is identical to the heat
loss by the hot water (or gain by the cold water) if only the pressure of the
system remains constant throughout the experiment.

10. Experiment: Double pipe heat exchanger
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Name: Huda Jihangeer
1. What is counter-current flow in a heat exchanger?
the term refers to the relationship between the flow directions of the hot and
cold fluids, counter flow will have the fluids flowing against each other in
opposite directions
2. Why is efficiency in counter-current more than co-current?
the counter-current heat exchanger is able to maintain a larger temperature
difference between the hot and cold fluid along a large part of the heat
exchanger compared to the co-current heat exchanger
counter-current heat exchanger allows the heating of the cold fluid to a
temperature higher than the outlet temperature of the hot fluid, which is a feature
absent in the co-current heat exchanger This enables a higher efficiency for heat
transfer.
3. What is error that can happen during the experiment?
important source of error is the thermal stability of the laboratory in which the
experiments were carried out. Although the heat exchanger is thermally
insulated, the change of the room temperature may affect the flow

11. Experiment: Double pipe heat exchanger
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Name: Hunar Hamdi
1. Which one is more efficient in a double pipe heat exchanger co-current or
counter-current? And why
Countercurrent is more efficient because it exposes different levels of heat from
both pipes as they flow in the opposite direction
But the co-current there isn’t much of a different level of heat as the liquid flows
within the two pipes
2. What are the errors and the causes of error in this experiment?
There is two factors:
• One is human error which might be due to reading the data wrong
• Second is the heat loss from the pipes
3. If counter current is more efficient then why would we use a co-current
heat exchanger?
The co-current has the advantage of being easily controlled and not overheated
especially when it comes to sensitive materials even though it has a lower
efficiency

12. Experiment: Double pipe heat exchanger
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Name: Sntia Louay
1. How does a double pipe heat interchanger work?
In a double pipe heat exchanger as the name suggests there are two pipes which
one holds cold water and hot water is held by the other which this two pipes are
in contact without the liquid in it getting mixed
If the liquid in one of the pipes flows in the same direction as the other its called
co current heat exchanger
If they flow in the opposite directions of each other then it is a counter current
heat exchanger
2. What is the disadvantage of counter-current flow?
Counter current heat exchanger is more efficient when it comes to transferring
heat but it comes as a cost as it has less control and it may overheat
3. Why counter-current heat exchanger is better than co current?
Counter current heat exchanger is more efficient when it comes to transferring
heat but it comes as a cost as it has less control and it may overheat
4. How do you increase flow rate in a pipe?
By decreasing the diameter of the pipe
5. Is turbulent flow good for heat transfer?
Flow rate of the water inside the pipe can be increased with increasing the the
flow rate from the pump

13. Experiment: Double pipe heat exchanger
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Name: Ara Fakfre
1. Why the counter current flow is better than parallel flow?
The counter-current flow arrangement enhances the heat transfer
efficiency compared to parallel flow, as it maintains a larger
temperature difference between the two fluids along the length of
the exchanger. This allows for a more uniform temperature profile
and better overall heat transfer.
2. When this is design is used? Why?
The design is commonly used when precise temperature control is
required, as it maximizes the temperature driving force across the
length of the exchanger.
3. What are some industries that its used in?
It is employed in various industrial applications, including HVAC
systems, chemical processing, and power plants, where efficient
heat exchange is crucial.
4. Advantages of counter current flow:
a. Improved heat transfer efficiency. [conduction and
Conviction]
b. More uniform temperature distribution along the length.
c. Better utilization of the available temperature difference.
d. Consideration of physical properties of fluids, such as
thermal conductivity, viscosity, and specific heat, is crucial
in designing an efficient heat exchanger.
5. How the pipe material is selected?
The choice of materials for the pipes is critical, considering factors
like corrosion resistance, thermal conductivity, and cost.

14. Experiment: Double pipe heat exchanger
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References:
1. Ezgi, Cüneyt, and Özgür Akyol (2019). "Thermal Design of Double Pipe Heat
Exchanger Used as an Oil Cooler in Ships: A Comparative Case Study." J Ship Prod
Des 35. Available at: doi: https://doi.org/10.5957/JSPD.170009 [Accessed:
Nov./29/2023]
2. Linquip Team (2023), What are Double Pipe Heat Exchangers and Their Working
Principles? [online] Available at: https://www.linquip.com/blog/double-pipe-heat-
exchangers/#:~:text=The%20double%20pipe%20heat%20exchanger,and%20a%20nu
mber%20of%20bends. [Accessed: Nov./29/2023]