| dc.description.abstract | With the rapid development of satellite aerospace technology, mobile communications, and electronic components, the application of low-earth orbit (LEO) satellite communications has become feasible. However, during the operation of LEO satellites, the working temperatures vary significantly, ranging from 80°C on the sun-facing side to -40°C on the shadow side. Aluminum-ammonia grooved heat pipes are commonly used for satellite thermal management, but there is limited research near this temperature range. Therefore, this study experimentally measured the performance of aluminum-ammonia heat pipes within a working temperature range of -40°C to 80°C. It compared the performance variations under different cooling and heating methods, and examined the performance changes with tilt angles from 10° to horizontal when the evaporating section was higher then condensing section. The results showed that 2-side heating with 2-side cooling had the best performance. In the tilt test, as the angle increased, the maximum heat transfer rate and minimum thermal resistance of the heat pipe worsened. This is because the capillary force provided by the grooves is insufficient to counteract gravity, causing the liquid to fail to return to the evaporator section, leading to early dry-out and increased thermal resistance.
Currently, copper-water heat pipes are a well-established technology for ground applications. If applied to LEO satellites, they offer low cost, high flexibility, and high heat flux transfer capabilities. It can be used for heat transfer from internal heating elements to the component box. However, in low-temperature space applications, temperatures below 0 oC can cause water to freeze and expand, potentially damaging the wick structure and degrading performance. This study experimentally investigated the performance of copper-water sintered heat pipes with wick thicknesses of 0.9 mm and 0.5 mm, and three filling rate (60%, 70%, 80%). It observed the maximum heat transfer rate and minimum thermal resistance when the condensing section was at -40°C, and tested whether performance declined after repeated freeze-thaw cycles between -40°C and 80°C. The results showed that a wick thickness of 0.9 mm and a filling rate of 80% had the lowest thermal resistance. The thicker wick and higher filling rate provided more liquid in a flowing state, and enabling the heat pipe to operate. Furthermore, no performance degradation is observed after 172 freezing-thawing cycles. | en_US |