## 3 Results and Discussion
### Dynamic Response Characteristics of the Heat Pipe Systems
It could be seen that the total resistance of TSHP-1 kept on a low level before TSHP-1 was under the dry-out status when a certain heat load B input was 12 W. When heat load A was over 80 W, TSHP-1 was out of normal working for the total resistance grew up rapidly. Moreover, the evaporation resistance of TSHP-1 was a little higher than the total resistance of TSHP-1, and the condensation resistance of TSHP-1 was even lower than 0. The reasons for the above phenomena were that the steam pressure of TSHP-1 might be under a dynamic balance status. Moreover, the status could be speculated as follows: two ends of TSHP-1 were under high steam pressure, while the middle side of TSHP-1 was low with the increase in heat load B. Here, heat load B served as a thermal switch to adjust the steam pressure distribution of TSHP-1. Then, as a result, the surface temperature of the adiabatic section of TSHP-1 was slightly lower than that of the condensation section. Furthermore, the surface temperature of TSHP-1 might have been influenced by the thermal  
Figure 8: (**a**) The surface temperature distribution of TSHP-1 with different heat load A (named Q\({}_{c}\) in the figure) from 45 W to 80 W under a certain heat load B input of 12 W; (**b**) the surface temperature distribution of TSHP-1 with different heat load B (named as Q\({}_{a}\) in the figure) from 0 to 12 W under a certain heat load A input of 45 W; (**c**) the thermal resistance of TSHP-1 with different heat load A from 45 W to 80 W under a certain heat load B input of 12 W; (**d**) the thermal resistance of TSHP-1 with different heat load B from 0 to 12 W under a certain heat load A input of 45 W.  
conduction of the shell and then caused the phenomena above. As shown in Figure 8d, the thermal resistance of TSHP-1 with different heat load B from 0 to 12 W under a certain heat load A input of 45 W was demonstrated in detail. The overall trend was that the total resistance and condensation resistance of TSHP-1 decreased and then kept stable with the increase in heat load B, while the evaporation resistance increased first. The reason could be attributable to the addition of heat load B because the steam pressure of the condensation section was low firstly without heat load B input. Then, the condensation resistance was quite high compared with the others. As heat load B input increased, the balance of steam pressure was broken again. It caused the status where two ends of TSHP-1 were under high steam pressure, while the middle side of TSHP-1 was low. Therefore, the condensation resistance of TSHP-1 was even lower than 0. The thermal resistance of TSHP-1 before and after it dried out is shown in the following Figure 9a,b. Figure 9a demonstrates the thermal resistance of TSHP-1 with different heat loads A from 10 W to 55 W, which meant that TSHP-1 was under a stable status. Additionally, heat load B was unworking. It could be seen that the total resistance of TSHP-1 appeared to have a U-shaped change with the increase in heat load A. When heat load A input was low, the evaporation section of TSHP-1 was not fully started up, which caused some working liquid accumulation. As a result, the evaporation section resistance of TSHP-1 was high. With the increase in heat load A, the working liquid accumulation gradually improved, and the evaporation section of TSHP-1 even dried out because the evaporation section resistance increased. Moreover, TSHP-1 obtained the minimum resistance with heat load A input of 35 W. The thermal resistance of TSHP-1 with different heat load B from 0 to 12 W under a certain heat load A input of 45 W is shown in Figure 9b. TSHP-1 could reach a certain threshold critical power with a certain heat load B. Firstly, the total resistance of TSHP-1 increased with a low heat load B. During this process, the balanced steam pressure of TSHP-1 was broken, and it was hard for TSHP-1 to recover to a stable status with such a low heat load B.