  The Stirling engine, which possesses external combustion characteristics, a
simple structure, and high theoretical thermal efficiency, has excellent
potential for utilizing finite waste heat and cold resources. However,
practical applications of this technology suffered from thermal inefficiency
due to the discontinuity and instability of waste resources. Despite advances
in energy storage technology, temperature variations in the heat-exchanging
fluids at the hot and cold ends of the Stirling engine remained significant
obstacles. In this work, convective meta-thermal concentration (CMTC) was
introduced between the heating (cooling) fluids and the hot (cold) end of the
Stirling engine, employing alternating isotropic materials with high and low
thermal conductivities. It was demonstrated that CMTC effectively enhanced the
temperature difference between the hot and cold ends, leading to a remarkable
improvement in Stirling engine efficiency. Particularly, when the Stirling
engine efficiency tended to zero due to the limited availability of waste heat
and cold resources, CMTC overcame this limitation, surpassing existing
optimization technology. Further analysis under various operating conditions
showed that CMTC achieved a significant thermal efficiency improvement of up to
1460%. This work expanded the application of thermal metamaterials to heat
engine systems, offering an exciting avenue for sustainable energy utilization.
