Chinese scientists bring record-breaking Stirling generator to life while NASA’s patent remains on paper

beijingwalker · Nov 12, 2023

Chinese scientists bring record-breaking Stirling generator to life while NASA’s patent remains on paper

November 11, 2023

Although NASA The patent LEW-TOPS-80 is in line with this goal and proposes a thermoacoustic engine combined with a generator to generate electricity in space. However, no prototypes or specific performance metrics have been presented yet.

The thermoacoustic Stirling generator prototype has achieved promising results. Photo: Handout

Developed by the Technical Institute of Physics and Chemistry (TIPC) of the Chinese Academy of Sciences (CAS), the Chinese generator is about 2 meters (6½ feet) long and has a dumbbell-like shape.

According to Professor Hu Jianying of TIPC, it works with impressive efficiency.

“The current efficiency of thermoelectric conversion is about 28 percent; With a hotter 600-degree heat fluid, the efficiency could reach 34 percent,” he said.

This efficiency can rival that of steam turbines.

Professor Luo Ercang from TIPC highlighted the generator’s reliability, simple design, few moving parts and compatibility with various heat sources.

“It operates quietly and efficiently and can utilize various types of heat, including solar energy, waste heat and biomass,” Lou is quoted as saying in a CAS statement.

The innovative system consists of a thermoacoustic Stirling engine and a linear motor, which are surrounded by a rigid shell. The engine converts heat into sound waves that resonate and form a stable sound field. These waves then drive a piston, which in turn generates electricity.

“The working fluid is high-pressure helium at 15 megapascals, and the lack of mechanical parts that require lubrication means the generator could have a lifespan of more than a decade,” Hu said.

While Stirling engine technology – first developed in 1816 by Scottish engineer Robert Stirling – faces manufacturing challenges due to the material requirements of accommodating high-pressure gas, its low noise levels and high reliability remain attractive for specific contexts.

Sweden’s use in submarines and China’s own advances in Stirling engines for naval applications underscore the value of the technology. Modern air-independent propulsion (AIP) submarines, including the Chinese Navy’s Type 039A/B, use Stirling engines for power.

The thermoacoustic generator developed by CAS not only breaks new ground for traditional Stirling engine designs, but also integrates a motor that converts sound directly into electrical energy.

Hu noted that the engine’s design avoids harmful vibrations and maintains an airtight seal within the mechanism.

“The linear motor, consisting of a piston driven by sound waves, permanent magnets and coils, contributes to the high conversion efficiency. Its symmetrical design also eliminates some harmful vibrations,” he said.

“The linear motor maintains a very small space between the piston and cylinder, about the thickness of a human hair. This prevents the parts from touching each other while maintaining the airtight environment inside.”

Although there is no scientific work related to the CAS announcement, the breakthrough highlights the potential of thermoacoustic Stirling generators to revolutionize power generation in various areas.

“It is a promising new-generation technology for solar thermal energy, biomass power generation and distributed energy systems,” Hu said.