## 3 Results and Discussion
### Influence of the Refrigerant Type  
Figure 9 and Table 4 delineate the internal parameter distribution and performance characteristics of the PCTCS when using three distinct refrigerants: R-113, R-134a, and R-32. As displayed in Figure 9a and Table 4, the PCTCS with R-32 and R-113 revealed the highest and lowest operating pressures, respectively. Interestingly, these pressures were inversely proportional to the total pressure drop. In connecting pipe 6-7, the total pressure drop of the PCTCS with R-113 demonstrated an upward trend along the direction of the refrigerant flow, an observation not mirrored in the PCTCS with R-134a and R-32. This discrepancy can be traced back to the distinct physical properties of the refrigerants. As highlighted in Figure 9b, within pipe 6-7, both the x and \(\alpha\) for the PCTCS with R-113 increased significantly with the decrease in refrigerant pressure, a situation not observed with the R-134a and R-32 refrigerants. The rise in x engenders an increase in the frictional pressure drop within the two-phase region. Consequently, an escalation in the total pressure drop in the PCTCS using R-113 refrigerant occurred within pipe 6-7. Figure 9b demonstrates the alignment of the x and \(\alpha\) trends for the R-134a and R-32 systems, while the PCTCS with R-113 diverged slightly. This divergence was particularly evident at the inlet of the first evaporator: the subcooling zone for the PCTCS utilizing R-134a and R-32 was noticeably small but substantially larger for the PCTCS using R-113. Figures 9c and 8d further show that the PCTCS with R-32 had the lowest refrigerant and CPU temperatures and the largest heat transfer coefficients in both the evaporators and condenser. In contrast, the PCTCS with R-113 exhibited the highest refrigerant and CPU temperatures, coupled with the smallest heat transfer coefficients, and the PCTCS with R-134a exhibited intermediate values for these parameters. \begin{table}
\begin{tabular}{c c c c} \hline
**Parameter** & **Value** & **Parameter** & **Value** \\ \hline Pdt (kPa) & 83.21 & Tdt (\({}^{\circ}\)C) & 34.50 \\ Ppump (W) & 27.9 & \(\overline{\mathrm{T}}_{\mathrm{CPU}}\) (\({}^{\circ}\)C) & 78.72 \\ EERp & 115 & \(\overline{\mathrm{T}}_{\mathrm{cpu2}}\) (\({}^{\circ}\)C) & 79.50 \\ \(\mathrm{n}_{\mathrm{con}}\) & 0.513 & Tdcpu (\({}^{\circ}\)C) & 0.78 \\ \(\mathrm{dT}_{\mathrm{sub}}\) of the first & 14.44 & \(\mathrm{S}_{\mathrm{CPU}}\)\({}^{2}\) & 0.08 \\ \(\mathrm{dT}_{\mathrm{sub}}\) of the & & & \\ condenser outlet (\({}^{\circ}\)C) & 0.78 & \(\mathrm{S}_{\mathrm{cpu2}}\)\({}^{2}\) & 0.34 \\ \hline \end{tabular}
\end{table} 
Table 3: Simulation results of the PCTCS with default parameters. As delineated in Table 4, the PCTCSs utilizing R-32 and R-134a exhibited a total pressure drop and pump power of 26.8 kPa and 23.68 kPa and 12.3 W and 14.3 W, respectively. These figures were significantly lower than the 83.21 kPa and 27.9 W associated with the PCTCS employing R-113. In terms of efficiency, the PCTCSs with R-32 and R-134a surpassed that with R-113, boasting EERp and \(\eta_{\text{con}}\) of 224 and 260 and 0.792 and 0.634, respectively, compared to 115 and 0.513. Moreover, the degree of subcooling in the first mini-channel evaporator and condenser was remarkably minimal when R-32 and R-134a were employed. In terms of maximum temperature difference (Tdt), the PCTCS utilizing R-32 demonstrated the smallest at 11.82 \({}^{\circ}\)C, R-134a yielded a moderate Tdt of 17.97 \({}^{\circ}\)C, and