# The Effect of Arachidic Acid Mixtures on the Cooling Performance of a Heat Sink
## 5 Discussion  
On the basis of the several experiments performed, some conclusions can be outlined. First, when the generated heat increases, the peak temperature of the sink also increases. The effect of the PCM with respect to delaying the peak temperature is clearly shown in Figure 9. When the PCM melts at 2 W, it absorbs a large amount of energy during the phase transition, leading to enhanced thermal performance of the heat sink. Another important thermophysical criterion that affects the thermal performance of the sink is the specific heat C\({}_{\text{P}}\). This is clearly shown in Figure 10, where the PCMs do not melt at 0.5 W, but have a smaller peak temperature due to the energy absorbed by the PCM as specific heat during temperature change from ambient to peak temperature. The effect of the thermal conductivity of the PCM is demonstrated in Figure 12, where all PCMs are totally melted and have almost the same specific heat. The higher the thermal conductivity is, the lower the peak temperature is reached. As the thermal conductivity increases, the heat transfer rate between the bottom and the top surface of the PCM will increase, making the temperature gradient uniform. In addition, when the surface temperature of the PCM increases, the natural convection at the surface will increase, making it possible for the heat to dissipate faster.  
Moreover, the influence of the mixtures was investigated in this work. Unlike Arachidic acid, the sodium mixture makes the PCM suitable for applications with lower heat dissipation, as shown in Figure 11, where the sodium mixture was completely melted  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **Peak Temperature (\({}^{\circ}\)C)** & **Time to Steady State (s)** \\ \hline
0.5 W & 50 & 900 \\
1 W & 72 & 850 \\
2 W & 109 & 800 \\
0.5 W (AA) & 41.5 & 473 \\
1 W (AA) & 65 & 1120 \\
2 W (AA) & 89 & 1100 \\
0.5 W (AA + Potassium) & 42.5 & 500 \\
1 W (AA + Potassium) & 58.5 & 560 \\
2 W (AA + Potassium) & 95.25 & 1500 \\
0.5 W (AA + Sodium) & 42 & 908 \\
1 W (AA + Sodium) & 73 & 1160 \\
2 W (AA + Sodium) & 104 & 1607 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Peak temperature and time to reach steady state.  
at 1 W and the peak temperature of the sink was delayed by 320 s. Thus, this PCM is appropriate for electronic devices with intermediate heat dissipation.  
Finally, for the potassium mixture, despite this PCM not melting at 1 W, it is appropriate for application in electronic devices with intermediate heat dissipation, because the melting point of this mixture is 50 \({}^{\circ}\)C. The reason for it not melting significantly at 1 W is that the potassium mixture enhances the thermal performance of the heat sink by lowering its melting peak from 72 to 59 \({}^{\circ}\)C. Therefore, the potassium mixture enhances the performance for the pure Arachidic acid, making this PCM suitable for electronic devices with lower heat dissipation and enhancing the thermal performance for the electronic chip by increasing the specific heat and thermal conductivity. In addition, the potassium mixture has a much greater time delay than pure Arachidic acid. This is shown in Figure 12, where potassium delays the peak temperature by 1050 s instead of 300 s, as in the case of the pure Arachidic acid, thus resulting in a 3.5 time greater delay than pure Arachidic acid, and with better thermal performance for electronic devices with higher heat dissipation.