China tests a Stirling engine in orbit

[beijingwalker]

China tests a Stirling engine in orbit​

by Matt Williams, Universe Today
APRIL 6, 2023

The uncapped Stirling thermoelectric converter. Credit: China Manned Space Agency

The China National Space Agency (CNSA) has made considerable progress in recent years with the development of its Long March 5 (CZ-5) rocket and the completion of its Tiangong-3 space station. The agency also turned heads when it announced plans in June 2021 to create an International Lunar Research Station (ILRS) that would rival the Artemis Program. On top of all that, China upped the ante when it announced later that month that it also had plans to send crewed missions to Mars by 2033, concurrent with NASA's plans.


As part of their growing efforts to become a major power in space, which includes human exploration, China recently announced the completion of the first in-orbit test of a Stirling thermoelectric converter. The Shenzou-15 mission crew performed the test aboard Tiangong-3, and it was the first successful verification of the technology in space. This technology is also being investigated by NASA and is considered a technological solution to the challenges of space exploration, especially where long-duration stays and missions to locations in deep space are concerned.

Similar to how hydroelectric dams generate power, a Stirling unit converts heat into electrical energy through a series of piston-driven magnets. These pistons rely on a fuel source to generate heat, pushing the magnets back and forth through a coil of wire, generating electrical current. This process is known as the Stirling cycle, which is more efficient than solar-powered systems and conventional batteries. Compared to other power systems, it is also lightweight, has a simple structure, a quick start-up cycle, and produces minor vibrations and low noise.

All of this makes the technology appealing to spacecraft engineers and mission planners, who see it as a more sustainable means for providing power to spacecraft and surface habitats. On the one hand, it can reduce their dependence on solar energy, which is limited by solar cell efficiency and is not always accessible in certain environments. Around the moon's South Pole-Aitken Basin, where multiple agencies plan to build research stations before the end of the decade (including China's ILRS), a lunar night lasts fourteen days.

The Stirling power converter was developed by the Lanzhou Institute of Physics at the China Academy of Space Technology (CAST). It was transported aboard the space station by the Shenzou-15 crew and installed in the equipment cabinet in the Mengtian lab module. As the China Global Television Network (CGTN) reported, three in-orbit
experiments were carried out in the lab module before the test run. The converter produced a stable power supply throughout, reportedly achieving a level of thermoelectric conversion efficiency that reached "an advanced international level under the same isothermal ratio."

When paired with a nuclear reactor as a power source, Sterling engines could allow for long-duration stays on the moon and Mars, augmenting solar power, batteries, fuel cells, and other conventional power sources. NASA is currently researching the technology as part of its Kilopower Reactor Using Sterling Technology (KRUSTY) experiment, which evolved from previous efforts to develop nuclear power applications for space exploration. NASA and DARPA recently announced a partnership to test a prototype nuclear thermal propulsion system in space (scheduled for 2027).

Artist’s impression of four KRUSTY generators providing power to an outpost on the surface of Mars. Credit: NASA/STMD

Shortly after that, the UK Space Agency (UKSA) announced they had contracted with Rolls-Royce to develop nuclear systems for space exploration, which could power a future lunar base. These and other attempts to realize next-generation power and propulsion systems are part of a growing effort to realize the next great leap in space exploration. They also reflect an undeniable truth about the modern space age: it's an international affair characterized by competition and cooperation.

China tests a Stirling engine in orbit

The China National Space Agency (CNSA) has made considerable progress in recent years with the development of its Long March 5 (CZ-5) rocket and the completion of its Tiangong-3 space station. The agency also turned heads when it announced plans in June 2021 to create an International Lunar...

phys.org

 

[beijingwalker]

China's space agency reportedly tested a Stirling converter in orbit​

Stirling converters could allow deep space missions to massively reduce their reliance on potentially scarce solar energy.
Apr 06, 2023 07:33 AM EST

Chinese Tianhe core module of the Tiangong space station
gremlin/iStock

China's Shenzhou-15 mission crew aboard the China Space Station (CSS) has reportedly completed testing on a free-piston Stirling thermoelectric converter, according to a report from state-owned media in China.

The successful test marks the first time China has verified this type of technology in orbit. The experimental technology, which NASA has also investigated, has the potential to provide crucial backup energy to deep space missions.

NASA and China have both experimented with Stirling converters​

The Stirling thermoelectric converter is an energy supply technology for space travel that efficiently converts thermal energy into electric energy, enabling spacecraft to reduce their reliance on solar power.

In the Stirling converter, a piston is set in motion by heat generated by a fuel source. The piston then moves a magnet back and forth through a coil of wire to generate an electrical current. The piston is typically suspended in a helium gas bearing to prevent physical wear.

The Lanzhou Institute of Physics at the China Academy of Space Technology developed an iteration of the Stirling converter. According to the CGTN report, it is lightweight, has a simple structure, makes little noise, starts up quickly, and doesn't vibrate much, making it ideal for spacecraft.

The report also claims the technology could play a vital role in the China National Space Administration's (CNSA's) plans to send crewed missions to the Moon and deep space.

China's space industry has made great strides in recent years. Last week, a Chinese startup called Space Pioneer became the first startup in the world to reach orbit on its first launch attempt. The CNSA, meanwhile, recently finished constructing its Tiangong space station, and it performed the first in-situ detection of water from the lunar surface with its Chang'e-5 lunar probe last year.

NASA has also experimented with Stirling converter technology, though its Advanced Stirling Radioisotope Generator (ASRG) was discontinued in 2013. An animation of the technology NASA was working on can be viewed in the video below.

China's Tiangong space station enables in-orbit Stirling converter test​

In order to test the Stirling converter technology, prototypes were sent up to the China Space Station, also known as the Tiangong Station, where they were installed in the equipment cabinet of the station's Mengtian lab module.

The device reportedly ran stably during the test and produced "better-than-expected" performance indicators, according to CGTN. It's worth noting that the CNSA has remained tight-lipped about the technology, and no concrete numbers have been shared.

The Mengtian lab of the CSS was launched in October 2022. It was the third and final module to be launched to orbit, marking the completion of the CSS. The module is used to study microgravity and perform experiments in materials science, fluid physics, and other fields.

China's space agency reportedly tested a Stirling converter in orbit

Stirling converters could allow deep space missions to massively reduce their reliance on potentially scarce solar energy.

interestingengineering.com