Aim of the experiment “The aim of this experiment is to determine the amount of heat loss from hot water by parallel flow current in the pipes of the heat exchanger.” Double Pipe Heat Exchanger. 3 Chemical Engineering Department. Stage III Introduction to double pipe heat exchangers A double pipe heat exchanger, also known as a hairpin heat exchanger, is a type of heat exchanger used to transfer heat between two fluids. It consists of two concentric pipes, one inside the other, forming a “U” or “hairpin” shape. One fluid flows through the inner pipe, while the other flows through the annular space between the inner and outer pipes. This design allows for efficient heat transfer between the two fluids, making it suitable for various applications, such as cooling or heating processes in industrial systems. Types of flows in double pipe heat exchangers In a double pipe heat exchanger, there are two primary flow arrangements, each with its variations, however, we’re are going to be focusing on two simple arrangements only, as they would suffice to comprehend the basic ideas behind double pipe heat exchangers. One flow arrangement is called “parallel flow” and the other is called “counter flow”. The latter will be explained in our next experiment. Parallel flow or uni-flow: in this type of flow, both the hot and cold fluids flow in the same direction, entering one end of the inner pipe and exiting the other end. This arrangement is simple but generally less efficient for heat transfer because the temperature difference between the two fluids decreases along the length of the exchanger. Figure 1: simple parallel flow diagram. By “Research Gate” Double Pipe Heat Exchanger. 4 Chemical Engineering Department. Stage III However, when there’s a significant temperature difference between the two fluids at the inlet, parallel flow heat exchangers can be more efficient for heat transfer. Both arrangements have advantages and disadvantages and are used depending on the system requirements. Theoretical calculation for heat transfer in double pipe heat exchangers Heat Transfer: Heat transfer is the process of the exchange of thermal energy between two objects or systems that are at different temperatures, and the heat energy always flows from the high temperature object or system to the low ones because the entropy of an isolated system can never decrease. There are several ways to calculate the amount of heat added or lost by an object or a system. However, in this experiment a relatively simple equation can be used to determine the amount of heat lost from the hot water, which is equal to the amount of heat added to the cold water. When pressure is held constant throughout the process, the amount of heat transfer will be equal to the change in enthalpy of the system and therefore can be calculated using constant pressure enthalpy change equation. 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:

1. Faculty of Engineering
Chemical Engineering Department
Double Pipe Heat Exchanger
Experiment
Prepared by:
Amirjan Shawkat
Hunar Hamdi
Huda Jigangir
Dima Jawhar
Ara Fakhir
Hana Kamal
Sntia Louay
25/OCT/2023
Supervisors: Mr. Mabast
Qadr

2. Chemical Engineering Department.
Stage III
Contents
Aim of the experiment 3
Introduction to double pipe heat exchangers 4
Types of
fl
ows in double pipe heat exchangers 4
Theoretical calculation for heat transfer in double pipe heat exchangers 5
Procedure and calculations 6
Summary 7
References 8
Double Pipe Heat Exchanger. 2

3. Chemical Engineering Department.
Stage III
Aim of the experiment
“The aim of this experiment is to determine the amount of heat loss from hot water by
parallel
fl
ow current in the pipes of the heat exchanger.”
Double Pipe Heat Exchanger. 3

4. Chemical Engineering Department.
Stage III
Introduction to double pipe heat exchangers
A double pipe heat exchanger, also known as a hairpin heat exchanger, is a type of heat
exchanger used to transfer heat between two
fl
uids. It consists of two concentric pipes,
one inside the other, forming a “U” or “hairpin” shape. One
fl
uid
fl
ows through the inner
pipe, while the other
fl
ows through the annular space between the inner and outer pipes.
This design allows for e
ffi
cient heat transfer between the two
fl
uids, making it suitable for
various applications, such as cooling or heating processes in industrial systems.
Types of flows in double pipe heat exchangers
In a double pipe heat exchanger, there are two primary
fl
ow arrangements, each with its
variations, however, we’re are going to be focusing on two simple arrangements only, as
they would su
ffi
ce to comprehend the basic ideas behind double pipe heat exchangers.
One
fl
ow arrangement is called “parallel
fl
ow” and the other is called “counter
fl
ow”.
The latter will be explained in our next experiment.
Parallel
fl
ow or uni-
fl
ow: in this type of
fl
ow, both the hot and cold
fl
uids
fl
ow in the
same direction, entering one end of the inner pipe and exiting the other end. This
arrangement is simple but generally less e
ffi
cient for heat transfer because the
temperature di
ff
erence between the two
fl
uids decreases along the length of the
exchanger.
Figure 1: simple parallel
fl
ow diagram.
By “Research Gate”
Double Pipe Heat Exchanger. 4

5. Chemical Engineering Department.
Stage III
However, when there’s a signi
fi
cant temperature di
ff
erence between the two
fl
uids at the
inlet, parallel
fl
ow heat exchangers can be more e
ffi
cient for heat transfer. Both
arrangements have advantages and disadvantages and are used depending on the
system requirements.
Theoretical calculation for heat transfer in double pipe heat
exchangers
Heat Transfer: Heat transfer is the process of the exchange of thermal energy between
two objects or systems that are at di
ff
erent temperatures, and the heat energy always
fl
ows from the high temperature object or system to the low ones because the entropy of
an isolated system can never decrease.
There are several ways to calculate the amount of heat added or lost by an object or a
system. However, in this experiment a relatively simple equation can be used to
determine the amount of heat lost from the hot water, which is equal to the amount of
heat added to the cold water.
When pressure is held constant throughout the process, the amount of heat transfer will
be equal to the change in enthalpy of the system and therefore can be calculated using
constant pressure enthalpy change equation.
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 speci
fi
c heat capacity of the system (J/g°C)
ΔT: di
ff
erence in temperature of the system °C.
Double Pipe Heat Exchanger. 5

6. Chemical Engineering Department.
Stage III
Procedure and calculations
Figure 2: gunt hamburg WL 302 double pipe heat exchanger
The procedure is pretty simple.
• In this particular experiment, the water is heated to 40-50°C inside the heater which
readily has a pump attached to it, in order to control the
fl
ow rate of the heated water.
• The valve on the right is closed in order to allow both of the water streams
fl
ow parallel
to each other (Uni-
fl
ow). See
fi
gure 3.
• Both heated water and cold water pumps are then activated in order to initiate the water
fl
ow through the inner and outer pipes. The hot water will
fl
ow through the inner pipe,
and the cold water will
fl
ow through the outer pipe. It’s important to note that the cold
water will never mix with the hot water.
• The temperature values can be recorded directly from each indicator.
• Now having mass of the hot water and temperature values at each point, the amount of
heat lost by the hot water can be calculated using enthalpy change equation.
Double Pipe Heat Exchanger. 6

7. Chemical Engineering Department.
Stage III
Figure 3:
fl
ow diagram of double pipe heat exchanger (WL 302)
Uni-
fl
ow mode.
Summary
A double pipe heat exchanger is a type of heat exchanger used to transfer heat between
two
fl
uids. It consists of two concentric pipes, one within the other. There are generally
two types of
fl
ows in double pipe heat exchanger, parallel
fl
ow (uni-
fl
ow) and counter
fl
ow.
The amount of heat transfer can be calculated in double pipe heat exchanger by pumping
di
ff
erent temperature
fl
uids through inner and outer pipes and recording the temperature
values at each point.
Double Pipe Heat Exchanger. 7

8. Chemical Engineering Department.
Stage III
References
• Linquip Team. (L.A: OCT/2023). What are double pipe heat exchangers and their
working principles? Available at: https://www.linquip.com/blog/double-pipe-heat-
exchangers/
• Gunt Hamburg. 2023. WL 302 Heat transfer in the tubular heat exchanger. Available at:
WL 302 Heat transfer in the tubular heat exchanger
• Britannica. (L.A: OCT/2023). Heat Transfer, De
fi
nition and Facts. Available at: https://
www.britannica.com/science/heat-transfer
Double Pipe Heat Exchanger. 8