## 5 Experimental Tests Results, and Discussion
### Effect of Input Current to TEC  
The cooling effect generated by the TEC module depends upon various parameters such as supply current, heat removed from the hot surface. However, the cooling effect is largely depending upon the applied current to the TEC module. Different current inputs of 2, 4, 6 and 8 A have been applied to the TEC to examine the performance of the TEC system. Figure 3 shows the temperature distribution of the system. As more current is applied to the TEC, a large amount of cooling effect is generated by TEC. The cooling temperature varied from 16 \({}^{\circ}\)C to 9.2 \({}^{\circ}\)C when the input current to the system is varied from 2 A to 8 A. It is also observed that the cooling effect increased with increasing the supply current to the TEC. Table 4 gives cooling temperature values at various times. As the TEC draws more current from the supply, it generates a more cooling effect on the cold side, leading to decreased temperature. As the current increased from 2 A to 8 A, a maximum 40% decrement in the temperature was observed. Furthermore, the bulk mean temperature of the water inside the cold plate is plotted to cool down the temperature at the different applied currents. The bulk mean temperature is used to calculate the heatremoval from the cold plate. In this case, to measure the bulk mean temperature, the inlet, and outlet of cold plate piping were recorded (as shown in Figure 2b). The average of the top and bottom cold plate inlet and outlet gives bulk mean temperature. Figure 4 gives bulk mean temperature distribution against time for various applied currents. The total heat removal rate combined from the top and bottom surface of the cold plate is plotted as a function of time in Figure 5.  
The heat removal rate is calculated using Equation (8) in the mathematical model. It is observed from the graphs that the heat removal rate increases with the increasing applied current to the TEC module from 2A to 8A. As the TEC module draws more current from the supply, the temperature on the hot side of the plate also increases with the increment to the current. That leads to more amount of heat carried out by the fluid inside the cold plate. However, it is observed from Figure 5 that the heat removal rate remains constant for the specifically applied current during the whole experiment. The amount of heat removal rate from the cold side of the cold plate heat exchanger is plotted against time in Figure 6. The calculation for the heat removal rate from the cold side of the plate is mentioned in the mathematical model. Figure 6 indicates that the heat removal rate at first increases with time, and after that, it remains constant during the whole experiment. It can be observed that the heat removal rate from the cold side is less compared to Figure 5, which is the heat removal rate from the hot side of the cold plate. Since the cold side of the cold plate is in contact with the TEC module's cold side, there is a negligible amount of heat generated during the experiment. Still, the heat removal rate increased from 10 to 400 W as the applied current increased from 2 to 8 A. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Time (s)** & **2 A** & **4 A** & **6 A** & **8 A** \\ \hline
5000 & 16 \({}^{\circ}\)C & 13.4 \({}^{\circ}\)C & 10.6 \({}^{\circ}\)C & 9.2 \({}^{\circ}\)C \\ \hline
10,000 & 15.2 \({}^{\circ}\)C & 11.3 \({}^{\circ}\)C & 8.4 \({}^{\circ}\)C & 6.8 \({}^{\circ}\)C \\ \hline
15,000 & 14.9 \({}^{\circ}\)C & 10.7 \({}^{\circ}\)C & 7.9 \({}^{\circ}\)C & 6.4 \({}^{\circ}\)C \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Temperature values at various applied currents to thermoelectric. Figure 3: Final cooling temperature at various inlet currents of 2A, 4A, 6A, and 8A. The coefficient of performance (COP) is plotted in Figure 7 using Equation (10) to examine the system's performance. It is observed that the COP of the system increases with increasing the applied current to the TEC modules.