## 5 Flight Verification and Data Analysis
### Analysis of Heat Transfer Characteristics On-Orbit  
#### 5.5.1 Heat Transfer Characteristics of TCB in Module  
In order to verify the heat transfer characteristics of the thermal control system on orbit, the global temperature and hydraulic parameters were analyzed. In order to express the relationship between the heat transfer parameters and the heat transfer characteristics accurately, the characteristic parameters are defined here. According to the heat transfer characteristics of a certain rack \(i\), the active heat transfer capacity is defined as follows:  
\[\phi_{\mathrm{i}}=c\cdot Q_{mi}\cdot\rho\cdot\Delta T_{i} \tag{14}\]  
where \(c\) is specific heat capacity of working medium (j/kg\(\cdot\)K); \(Q_{mi}\) is the total flow rate of the rack \(i\) (m\({}^{3}\)/s); \(\rho\) is the density of working medium (kg/m\({}^{3}\)); \(\Delta T_{i}\) is the temperature difference between inlet and outlet of rack \(i\) (K). Therefore, we define the ratio of the heat power transferred through the fluid loop consumption to the whole rack's heating power as the active heat transfer efficiency:  
\[\eta_{i}=\ \frac{\phi_{\mathrm{i}}}{\phi_{\mathrm{i}}}\times 100\%=\frac{c \cdot Q_{mi}\cdot\rho\cdot\Delta T_{i}}{\phi_{\mathrm{i}}}\times 100\% \tag{15}\]  
where \(\phi_{\mathrm{i}}\) is the total heat power of rack \(i\) (W); \(\phi_{\mathrm{i}}\) is the active heat transfer capacity (W). Table 4 shows the power of each payload and the valve opening setting of the whole system. The power of payload rack 5 will change with the switch of working mode; the rest of the payloads maintain a constant working state. Figure 21: Bypass pressure difference response during rack on-orbit adjustment process. Figure 22a shows the relationship between total flow distribution and power of each rack under this condition. The flow rate of payload rack 1, payload rack 4 and payload rack 7 on orbit are all above 120 L/h. Payload rack 6 is not working, so its flow rate is 0. Branch 1 of payload rack 3 is in working condition with a flow distribution of 28.6 L/h. The flow rate is basically proportional to the power of the rack. Figure 22b shows the global temperature changes during the system mode switching. When the power of the system is 1605 W, the liquid supply temperature of the system is about 21.3 \({}^{\circ}\)C and the average temperature of recirculation is 23.5 \({}^{\circ}\)C. The temperature difference between the inlet and outlet of the TCB can reach 2.2 \({}^{\circ}\)C. Combined with the total flow rate of the system and the property of working medium, the active heat dissipation of the system can be calculated to be 1518.6 W. The heat transfer efficiency of the system is 87%. When the power of the system increases to 2723 W, both the outlet temperature and the inlet temperature rise to a certain extent; the maximum temperature difference is 3.3 \({}^{\circ}\)C, the maximum heat transfer capacity of the fluid loop reaches 2280 W and the total heat exchange efficiency of the system reaches 83.7%. Table 5 provides the flow distribution and steady state temperature distribution in the partial payload rack and the whole system. From the analysis of the data, we can draw a conclusion: the integrated thermal control management system can realize the temperature control and heat dissipation of all the scientific experimental loads in this module of CSS, the heat transfer efficiency of the second stage inside the rack is more than 80% and some racks are close to 90%. The overall heat transfer efficiency of the TCB system reaches more than 83%, which realizes the heat collection and dissipation of the loads in the module.