4.5 Temperature Drop with PCM Materials
107
each material begins to absorb a large quantity of heat initially by the process of
melting, thus causing a rapid drop in temperature. After reaching the lowest point
in the cooling curve, the drop in temperature then decreases gradually, as shown by
the rising of the individual curves towards the X-axis. The forced convection of air
in the wind tunnel assists in further cooling of the helmet until the curves approach
the steady state. After the PCM contained in the textile liner have melted (attaining
the highest drop in temperature), there would not be further absorption of heat.
4.5.2 Paraffinic PCM at Speed of 75 kph
The comparison graphs for PCM materials at 75 kph speed are shown from Figs. 4.32,
4.33, 4.34 and 4.35. It was observed from the experiment data that the drop in
temperatures achieved by using different PCM materials is within a very close range
of 3.1–3.8 °C. This can be attributed to the melting point of the PCM materials,
which are very close to one another as indicated by the DSC graphs (Figs. 4.38, 4.39
and 4.40, Fig. 4.41).
It was also observed from Figs. 4.32, 4.33, 4.34 and 4.35 that the drop in temperature achieved by PCM materials, non-woven, foam, fabric and composite, were
3.1 °C, 3.7 °C, 3.8 °C and 3.7 °C, respectively, over the total experimental time of
60 min. These figures indicate that the drop in temperature is rapid for the initial
part of the experiment, and as the time elapses, the drop in temperature gradually
decreases.
Figure 4.32 shows the drop in temperature of PCM non-woven material. It was
observed from the figure that the maximum drop in temperature achieved was 3.1 °C
Drop in temp. Deg.C
12.00
Control (Mean-Ambient)
10.00
8.00
PCM nonwoven material (Mean-Ambient)
Drop in temp.
6.00
4.00
2.00
0.00
0:00:00
0:07:12
0:14:24
0:21:36
0:28:48
0:36:00
0:43:12
0:50:24
0:57:36
1:04:48
2.00
4.00
6.00
Time:h:mm:ss
Fig. 4.32 Comparison graph for PCM non-woven material at 75 kph speed
107
each material begins to absorb a large quantity of heat initially by the process of
melting, thus causing a rapid drop in temperature. After reaching the lowest point
in the cooling curve, the drop in temperature then decreases gradually, as shown by
the rising of the individual curves towards the X-axis. The forced convection of air
in the wind tunnel assists in further cooling of the helmet until the curves approach
the steady state. After the PCM contained in the textile liner have melted (attaining
the highest drop in temperature), there would not be further absorption of heat.
4.5.2 Paraffinic PCM at Speed of 75 kph
The comparison graphs for PCM materials at 75 kph speed are shown from Figs. 4.32,
4.33, 4.34 and 4.35. It was observed from the experiment data that the drop in
temperatures achieved by using different PCM materials is within a very close range
of 3.1–3.8 °C. This can be attributed to the melting point of the PCM materials,
which are very close to one another as indicated by the DSC graphs (Figs. 4.38, 4.39
and 4.40, Fig. 4.41).
It was also observed from Figs. 4.32, 4.33, 4.34 and 4.35 that the drop in temperature achieved by PCM materials, non-woven, foam, fabric and composite, were
3.1 °C, 3.7 °C, 3.8 °C and 3.7 °C, respectively, over the total experimental time of
60 min. These figures indicate that the drop in temperature is rapid for the initial
part of the experiment, and as the time elapses, the drop in temperature gradually
decreases.
Figure 4.32 shows the drop in temperature of PCM non-woven material. It was
observed from the figure that the maximum drop in temperature achieved was 3.1 °C
Drop in temp. Deg.C
12.00
Control (Mean-Ambient)
10.00
8.00
PCM nonwoven material (Mean-Ambient)
Drop in temp.
6.00
4.00
2.00
0.00
0:00:00
0:07:12
0:14:24
0:21:36
0:28:48
0:36:00
0:43:12
0:50:24
0:57:36
1:04:48
2.00
4.00
6.00
Time:h:mm:ss
Fig. 4.32 Comparison graph for PCM non-woven material at 75 kph speed