Yusuke Goto/ Dynax Corporation, Hiroaki Izumi/ Dynax Corporation,

Mamoru Aizawa/ Dynax Corporation, Hiroo Yugami/ Graduate School of Engineering, Tohoku University

It is important to utilize the solar energy efficiently1-2). However, conventional solar thermal collectors have some drawbacks of high cost, heavy weight and low temperature output. These drawbacks prevent from spreading of the market of solar thermal collectors, especially in Japan.

To find a solution to the problems, we propose an absorber / aerogel one-piece structure for high temperature solar thermal collectors. TiOxNy and silica aerogel were employed as a selectively solar-absorbing coating of absorber and as an optically transparent thermal insulator, respectively. Selectively solar-absorbing coatings must show lower reflectance and lower emittance. We have developed selectively solar-absorbing coatings of which optical property was a = 98.5, £ = 3 %. Wet coating of newly designed TiOxNy precursor enabled fabricating selectively solar-absorbing coatings, easily. Shrinkage of silica aerogel had to be minimized to produce an absorber / aerogel one-piece structure. Selectively solar-absorbing coatings and silica aerogel were prepared via sol-gel processing.

Experimental