International Journal of Science, Engineering and Technology Research (IJSETR)
Volume 1, Issue 1, July 2012
Improving Thermal Comfort in Industrial Safety
Helmet Using Phase Change Material
S. Gowtham Vigneswaran, L. Arulmurugan

Abstract— Nowadays, the people working in
construction industry are not like to wear safety helmet
due to thermal discomfort. During hot weather with no
airstream, the helmet surface temperatures can reach up
to 50̊ to 60̊C that heat could be transferred by conduction
from the outer surface to the inner surface which cause
uncomfortable to the worker. The proposed method is to
reduce the thermal discomfort by using phase change
material (PCM) to absorb and to store the excessive heat
produced by the solar radiation to attain the comfort
cooling for the wearer. The PCM is packed in a thin
flexible aluminum casing and placed underneath the
outer layer of the helmet. The virtual instrument
environment with Data Acquisition (DAQ) is used to
acquire the temperature in both the Helmet and PCM
based helmet with solar radiation under no airstream.
The experimental investigations are compared and found
that the PCM based helmet have improved thermal
comfort level.
.
Index Terms— Data acquisition, Industrial safety
helmet, Phase change material, Thermal comfort.
Manuscript received Oct 15, 2011.
First Author name, His Department Name, University/
College/ Organization Name, ., (e-mail: [email protected]).
City Name, Country Name, Phone/ Mobile NoSecond Author
name, His Department Name, University/ College/ Organization
Name, City Name, Country Name, Phone/ Mobile No., (e-mail:
[email protected]).
Third Author name, His Department Name, University/
College/ Organization Name, City Name, Country Name, Phone/
Mobile No., (e-mail: [email protected]).
I.
INTRODUCTION
Industrial safety helmets are widely used in
industries as a primary protection for workers. Helmets
can protect the workers from head impact, penetration
injuries, and electrical injuries such as those caused by
falling or flying objects, fixed objects, or contact with
electrical conductors, they also cause thermal
discomfort to the wearers at work. Thermal discomfort
is due to the overheat radiation inside the helmet who
working in construction industry (mainly during
summer season). The comfortable thermal condition
for the head is around 34.5̊ C. During the hot weather,
the temperature inside the helmet could reach 50 to
60 ̊C if there is no airstream and hypothermia can be
induced. The temperature inside the helmet could be
affected by the heat gained from solar radiation that
heat could be transferred by conduction from the outer
surface to the interior due to the temperature gradient
across the helmet layer. To avoid this problem, it is
desirable to maintain the helmet interior temperature to
around the body temperature of 38 ̊C. There are some
cooling techniques were practiced to cool the helmet
such as In air cooled system, the air duct is installed to
the chin bar of the helmet. In thermoelectric cooling
system, the power supply is needed for cooling the
helmet. These systems are not suitable for industrial
safety helmet. The proposed helmet cooling system
eliminating the requirement of the power supply and
uses the phase change material (PCM) to absorb and
store the heat generated from the solar radiation at a
relatively constant temperature to provide cooling to
All Rights Reserved © 2012 IJSETR
International Journal of Science, Engineering and Technology Research (IJSETR)
Volume 1, Issue 1, July 2012
the head and PCM is a light weight material, suitable
and comfortable for the wearer head. Heat inside the
helmet can be effectively stored in the PCM as it
changes phase from solid to liquid. Since the phase
change occurs at uniform melting temperature, the
helmet interior temperature can be maintained until the
PCM is fully melted. The cooling system can be
produced with a simple design, such as encapsulating
the solid PCM within a thin metal casing. Molten PCM
can be re-solidified by dissipating heat to the
surroundings when the helmet is not in use.
The average temperature underneath the
helmet shell was to be found for both normal and PCM
based helmet. Experimental results from the normal
and PCM based helmet are compared.
+
Figure 1 Experimental Setup
II. MATERIALS AND METHODS
A. Experimental Setup
An experiment to simulate the conditions of solar
radiation with no airstream, several components are
used. They are industrial safety helmet, head form,
K-Type thermocouple, closed container, light bulb and
DAQ
card
for
temperature
measurement.
Experimental investigations are done on the left side of
the helmet. Figure 2.1 shows the experimental setup. In
a closed box, the helmet is placed on the head form in a
stable position. The three light bulbs are focused on the
left top of the helmet to simulate the solar radiation.
The light bulbs are focused on the helmet for 30
minutes to attain a steady state. Eight thermocouples
were placed on the left side of helmet. One
thermocouple is placed on each front and back side of
the helmet and other six thermocouples are placed on
the left side of the helmet. Figure 2.2 shows the
thermocouple sampling areas. Eight thermocouples are
placed on the sampling zones. The thermocouples are
connected to data acquisition card and then the output
is connected to the computer.
Figure 2 Thermocouple sampling zones
All Rights Reserved © 2012 IJSETR
International Journal of Science, Engineering and Technology Research (IJSETR)
Volume 1, Issue 1, July 2012
Table 1 Properties of Paraffin Wax
B. Methodology
Experiment to simulate the solar
radiation under no airstream
Boiling point
Density
Specific heat capacity
Heat of fusion
Helmet
Without
PCM
Description
Melting temperature
Values
46 – 68 ̊c
>370 ̊ c
900 kg/m3
2.14-2.9 J/gk
200-220 J/g
With PCM
Selection of PCM
PCM pouch design
Data acquisition card
Virtual instrument environment
Results
.III. CONCEPTUAL DESIGN OF PCM BASED HELMET
A. PCM selection
During hot weather, the helmet surface temperature
can reach 50̊ c to 60̊ c which causes thermal discomfort
to the workers. To attain a thermal comfort, paraffin
wax is the suitable PCM material because it has a
melting temperature above 45̊ c. Paraffin wax belongs
to organic type. It has excellent storing heat capacity,
freeze without much super cooling, safe and
non-reactive, high heat of fusion, recyclable, waxy
solid and it is also relatively inexpensive and widely
available in the market. The properties of paraffin wax
are shown in Table 1
B. PCM pouch design
For pouch design, thin flexible aluminum foil is used.
Aluminum has high thermal conductivity and the thin
foil makes effective heat transfer. Four pouches are
placed underneath the outer layer of helmet. The
dimension of the pouch is estimated to be 9×5×0.5 cm
and is similar for all the pouches. Only ¾ of paraffin
wax is filled in each pouch and remaining space for
expansion of PCM. The PCM pouch can be removed
separately from the assembly so as to allow the
discharging of stored heat by submerging the pouch
into water.
C. Experimental Investigations
The experimental investigations to be done in normal
and PCM based helmet by the simulated solar radiation
with no airstream. The experimental setup is kept in
closed container to keep the heat in steady condition.
Three light bulb (180W) is used to simulate the solar
radiation and is focused from the top left of the helmet.
The heat is able to raise the temperature on the outer
surface of helmet from 30 °C ambient temperature to
50 to 60̊ C in 30 minutes under no airstream. The
average temperature underneath the helmet shell was
to be measured using lab view software. Then the PCM
is packed in a thin flexible aluminum casing and placed
underneath the outer layer of the helmet. Again the
average temperature underneath the helmet shell was
to be measured. Then the findings from the
experimental investigations are compared.
IV. RESULT AND DISCUSSION
The normal and PCM based helmet in simulated
solar radiation under no air stream are compared in the
All Rights Reserved © 2012 IJSETR
International Journal of Science, Engineering and Technology Research (IJSETR)
Volume 1, Issue 1, July 2012
temperature vs. time graph in Figure 3.1. From the
graph, it was clearly found that the average
temperature underneath the helmet shell in normal
helmet was increased above 45̊ c and the average
temperature underneath the helmet shell in PCM based
helmet was decreased to 35̊ c. Incorporation of PCM
based helmet, the result shows that the temperature
inside the helmet will take an extended time to exceed
the thermal comfort zone compared to a normal helmet
.
.
Figure 3 Temperature vs. time – with and without PCM
V. CONCLUSION
This paper presents the design of a helmet cooling
system using PCM to absorb and store the heat to
achieve comfort cooling for the wearer. From the
experiment, the impacts of the simulated solar
radiation under no airstream on the PCM cooling for
the industrial safety helmet have been investigated.
Then the findings from the experimental investigations
are compared and found that the PCM based helmet
have improved thermal comfort level.
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ACKNOWLEDGMENT
This project was done in K,S, Rangasamy college of
technology. They provided the instruments for the
project. This support is gratefully acknowledged.
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