## 4 Numerical Simulation Results on Heat Transfer Characteristics
### Different Volume Concentrations of Ethylene Glycol Aqueous Solution
#### 4.1.1 Ethylene Glycol Aqueous Solution of 60% Volume Concentration  
This model's heat dissipation method adopts forced liquid cooling. The fluid mass's inlet temperature is set to 20 \({}^{\circ}\)C. The inlet method is a mass flow inlet, whose inlet mass is the mass flow rate passing through the model component in the Fluent simulation. The outlet is set to a pressure outlet, and the cold plate material is aluminum alloy. The volume concentration of the cooling medium is set to 60%. The simulation of the cold plate is carried out by setting the heat flow density to 48 W/cm\({}^{2}\), setting the boundary conditions in Fluent, and setting the inlet mass flow rate of the two coolant pipes to 0.0711 kg/s and 0.0788 kg/s, respectively (this value is the mass flow rate passing through the first layer of the T/R assembly in the simulation of the 6 \(\times\) 5 parallel multi-branch cold plate model, which is the largest mass flow rate in the cold plate model, representative of the cold plate model). The number of iteration steps is set to 500, and the simulation results are obtained, in which the temperature clouds of the cold plate and T/R components are shown in Figure 14a, and the temperature profiles of the cold plate with coolant are shown in Figure 14b. Figure 13: The heat source position on the cold plate. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Volume** & **Density** & **Specific Heat** & **Dynamic** & **Thermal** \\
**Concentration** & **Density** & **Capacity** & **Viscosity** & **Conductivity** \\ \hline Unit & kg/m\({}^{3}\) & J/(kg\(\cdot\)K) & mPa\(\cdot\)s & W/(m\(\cdot\)K) \\
60\% & 1086 & 3084 & 5.38 & 0.349 \\
50\% & 1073 & 3281 & 3.94 & 0.380 \\
30\% & 1045 & 3645 & 2.2 & 0.453 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Physical parameters of different concentrations of ethylene glycol aqueous solution at 20 \({}^{\circ}\)C.  
We can see from Figure 13(a) in the T/R component a heat flow density of 48 W/cm\({}^{2}\), the cold plate on the T/R component cooling, cold plate overall temperature uniformity, the highest temperature of the T/R component 299.9 K, the lowest temperature of 296.9 K, the highest and lowest temperature difference of 2.95 K; from Figure 13(b) can be seen at the right end of the cold plate temperature is low, 293 K, is the set inlet temperature, from right to left observation can be seen that the temperature of the cold plate gradually increased, indicating that with the flow of coolant, the cooling capacity of the cold plate gradually decreased. In the cooling process of the cold plate, the temperature of the coolant is increased, indicating that the cooling capacity of the cold plate gradually decreased. The cooling capacity of the cold plate is increased, indicating that the cooling capacity of the cold plate is increased, indicating that the cooling capacity of the cold plate gradually decreased. Figure 14: Temperature profiles of cold plate and T/R assembly at heat flow density of 48 W/cm\({}^{2}\). is unchanged, which shows that the cold plate can deal well with the radar heating in the case of 48 w/cm\({}^{2}\) heat flow density. Observing the cooling capacity of the cold plate in the most unfavorable case for the 6 \(\times\) 5 parallel multi-branch cold plate, the temperature cloud is shown in Figure 14c,d. The flow rates of the two cooling pipes passing through the cold plate in the most unfavorable case are 0.0598 kg/s and 0.0560 kg/s. Comparing them with the cold plate with the largest mass flow rate, it is found that the maximum temperature of the T/R assembly with the smallest flow rate is 300.31 K, which is 0.45 K higher than the temperature of the cold plate at the time of the largest flow rate, and there is no temperature difference, which illustrates the homogeneous nature of the cooling capacity of the cold plate.