**6. Conclusions**

A buried tube granular bed with 3–5-mm hollow corundum balls as filler particles was developed to reduce heat storage. The experiment was performed at 1073.15 K, and the main conclusions are presented as follows:


**Author Contributions:** F.X. and S.Y. designed the manuscript; S.Y. and F.X. drafted the manuscript; F.X., X.W., and L.T. collected the data and revised the manuscript; L.W. and Y.D. checked the content and revised the manuscript. All authors made contributions to the study and the writing of the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** The authors gratefully acknowledge the financial support from the National key research and development plan of China (No. 2018YFB0605901).

**Conflicts of Interest:** The authors declare no conflict of interest.
