96
4 Results and Discussion
the speed of 55 kph. This was due to the forced convection at the speed of 75 kph
contributing to increased evaporation of the water contained in the PWAT material.
The maximum drop in temperature of 8.8 °C was achieved over the total experimental
time of 60 min.
It can be inferred from Figs. 4.18, 4.19, 4.20, 4.21 and 4.22 that, for low-velocity
tests (i.e. 0, 15 and 35 kph) the (mean–ambient) temperature curves for both control
and the PWAT material tend to be located above the X-axis which indicates less
cooling has been achieved. However, for road velocity tests (i.e. 55 and 75 kph),
these curves approach the X-axis much more closely which can be attributed to the
cooling achieved by higher wind speeds in the closed-circuit wind tunnel due to the
increased amount of the forced convection of air. It is evident from the high-velocity
graphs that an appreciable amount of cooling was achieved by using PWAT material
as an insert into the textile liner in the motorcycle helmet. Adding more water to the
PWAT material as necessary can increase the cooling.
In addition, a graph was plotted to compare the maximum drop in temperatures at
different speeds as shown in Fig. 4.23. The correlation between the maximum drop
in temperature and the wind speeds was established by this graph.
It was observed from the above figure that the drop in temperature using the
PWAT material as a textile liner in the helmet varied from 2.1 to a maximum of
8.8 °C depending on the wind speed. A gradual increase in temperature drop was
observed as the wind speed increased from 0 to 75 kph. The maximum drop in
temperature at various speeds was correlated by plotting an exponential trend line,
which was established by the equation
y = 2.4024e
0.0181x
(4.1)
Maximum drop in temp.Deg.C
10.0
9.0
8.0
7.0
y = 2.4024e
0.0181x
R
2 = 0.9531
(55.0, 7.0)
(75.0, 8.8)
6.0
5.0
4.0
3.0
2.0 (0.0, 2.1)
(15.0, 3.8)
(35.0, 4.3)
1.0
0.0
0
1 0
2 0
3 0
4 0
5 0
6 0
7 0
8 0
Speed in kph
Fig. 4.23 Comparison graph at different speeds for PWAT material
4 Results and Discussion
the speed of 55 kph. This was due to the forced convection at the speed of 75 kph
contributing to increased evaporation of the water contained in the PWAT material.
The maximum drop in temperature of 8.8 °C was achieved over the total experimental
time of 60 min.
It can be inferred from Figs. 4.18, 4.19, 4.20, 4.21 and 4.22 that, for low-velocity
tests (i.e. 0, 15 and 35 kph) the (mean–ambient) temperature curves for both control
and the PWAT material tend to be located above the X-axis which indicates less
cooling has been achieved. However, for road velocity tests (i.e. 55 and 75 kph),
these curves approach the X-axis much more closely which can be attributed to the
cooling achieved by higher wind speeds in the closed-circuit wind tunnel due to the
increased amount of the forced convection of air. It is evident from the high-velocity
graphs that an appreciable amount of cooling was achieved by using PWAT material
as an insert into the textile liner in the motorcycle helmet. Adding more water to the
PWAT material as necessary can increase the cooling.
In addition, a graph was plotted to compare the maximum drop in temperatures at
different speeds as shown in Fig. 4.23. The correlation between the maximum drop
in temperature and the wind speeds was established by this graph.
It was observed from the above figure that the drop in temperature using the
PWAT material as a textile liner in the helmet varied from 2.1 to a maximum of
8.8 °C depending on the wind speed. A gradual increase in temperature drop was
observed as the wind speed increased from 0 to 75 kph. The maximum drop in
temperature at various speeds was correlated by plotting an exponential trend line,
which was established by the equation
y = 2.4024e
0.0181x
(4.1)
Maximum drop in temp.Deg.C
10.0
9.0
8.0
7.0
y = 2.4024e
0.0181x
R
2 = 0.9531
(55.0, 7.0)
(75.0, 8.8)
6.0
5.0
4.0
3.0
2.0 (0.0, 2.1)
(15.0, 3.8)
(35.0, 4.3)
1.0
0.0
0
1 0
2 0
3 0
4 0
5 0
6 0
7 0
8 0
Speed in kph
Fig. 4.23 Comparison graph at different speeds for PWAT material