## 4 Analysis and Discussion of Results
### Interpretation of the Effects
#### 4.2.4 Mini Heat Exchanger Performance  
The \(G_{TR}\) enables the measurement of the heat dissipated from an electronic component to maintain the optimal operating temperature. As the electrical power of this component increases, both the heat transfer coefficient and the thermal resistance also rise. In the analysis, only variations in power had a significant impact on overall thermal resistance. However, both power and ambient temperature were statistically significant for the heat transfer coefficient (_h_). This is attributed to the relationship between ambient temperature (relative humidity) and the water temperature, which alters the thermophysical properties and leads to changes in heat transfer. Relative humidity influences air density and viscosity, impacting the convective heat transfer coefficient of air. Higher humidity enhances thermal capacity, while lower humidity reduces it, underscoring the role of air moisture in heat transfer. This is particularly pertinent since water cooling in the radiator relies on ambient air for heat dissipation. Furthermore, Figure 12 confirms that both temperature and relative humidity were measured, ensuring a comprehensive evaluation of all factors influencing heat transfer and reinforcing the reliability of the data collection.  
Figure 13 shows the pressure drop in the heat exchanger. Although the pressure drop increases as the volumetric flow rate rises, resulting in higher velocities and a higher Reynolds number, the pressure drop in the heat exchanger will continue to increase progressively. This occurs since the pressure drop is directly proportional to the Reynolds number. As the volumetric flow rate increased, the fluid velocity also increased, which led to a higher Reynolds number and, consequently, more significant pressure drops due to increased viscous friction.  
It is essential to enhance the heat transfer coefficient (_h_) to improve heat dissipation and reduce the overall thermal resistance (\(G_{TR}\)), as indicated by Equations (2)-(8). In the experiment, the heat transfer coefficient (_h_) reveals a limitation in thermal dissipation when thermal power reaches its maximum level. This occurs because the overall thermal resistance increases, hindering the necessary heat transfer to achieve the desired operating temperature of electronic components, such as the Central Processing Unit (CPU). However, within the established conditions and ranges, the overall thermal resistance of this heat exchanger could facilitate the heat dissipation of a processor with a Thermal Design Power (TDP) of 65 W, as analyzed in this study. Consequently, the temperature of the CPU case would be close to the temperature of the outer wall (\(T_{1}\)) of the mini heat exchanger, as illustrated in Figure 14. Statistical analysis revealed that the optimal operating conditions for the electronic component within the study range were achieved at a low power level (30 W), a high ambient temperature (29 \({}^{\circ}\)C), and a low volumetric flow rate (2.50 L\(\cdot\)min\({}^{-1}\)). However, the highest power condition (65 W) is also viable, as shown in Figure 11, where the maximum outer wall temperature remained below 73 \({}^{\circ}\)C, which is an acceptable threshold according to the thermal profiles of most processors [3; 31; 33; 42]. The highest temperature was recorded under warmer conditions, with an ambient temperature of 22 \({}^{\circ}\)C resulting in an average outer wall temperature of 66 \({}^{\circ}\)C when using a power of 65 W.  
Figure 12: Effect of ambient temperature and relative humidity on (\(T_{\infty}\)).  
Figure 13: Water temperature and pressure drops in the mini heat exchanger.