Absorber / alcogel using MS51 as starting material was done by supercritical drying. Silica aerogel cracked. Figure 8 shows photograph of structure sandwiched silica aerogel obtained from MS51. Although a copper panel expanded during supercritical drying, MS51 silica aerogel shrunk 4.1%. Silica aerogel cracked difference in expansion. To stop the shrinkage ratio of silica aerogel, starting material was changed from MS51 into TMOS, and the solvent was changed from IPA into ethanol. The shrinkage ratio of silica aerogel obtained from TMOS was 1.4 %. Then, one-piece structure, which did not cracked, was produced. Figure 9 shows photograph of structure sandwiched silica aerogel obtained from MS51 With the structure the selectively solar-absorbing coatings obtained from TMOS was not exposed to the open air at all. The light from solar simulator radiated on to the panel. The temperature went up 177 °C by radiation at 1000 W/m2.

Conclusion

1. Selectively solar-absorbing coatings

TiOxNy selectively solar-absorbing coatings were produced by the sol-gel method. The reflectance was lower 1 %.

The emission was 3%.

2. One-piece panel

The selectively solar-absorbing coatings were sandwiched by two silica aerogels. The one-piece structure temperature went up 177°C by radiation at 1000 W/m2. In addition, the very highly efficient solar heat panel may be developed.

Acknowledgements

The authors wish to thank Dr. Tajiri of AIST for silica aerogel development.

This research was supported by Advanced Technology Initiative for New Industry Creation of Hokkaido Bureau of Economy, Trade and Industry.

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