Solar Thermal Receiver

Abstract

The invention relates to solar thermal receiver for a solar thermal energy plant comprising a light absorber ( 11 ) comprising nanoparticles ( 13 ) in a host material ( 15 ) which is transparent in an absorbing range of the light absorber ( 11 ) and where the nanoparticles ( 13 ) ekhibit plasmonic resonances within the absorbing range of the light absorber ( 11 ), wherein the dispersion of the nanoparticles ( 13 ) in the host material is controlled in such a way that the mean distance between said nanoparticles ( 13 ) is lower than the wavelengths of light in the absorbing range of the light absorber ( 11 ) for generating near field radiation interactions between said nanoparticles ( 13 ). The size and the distribution of the nanoparticles ( 13 ) is chosen to obtain a cutoff wavelength, where light of higher wavelength than the cutoff wavelength is less absorbed than light at shorter wavelengths with respect to the cutoff wavelength reducing losses due to infrared radiation of the absorber.

1 . Solar thermal receiver for a solar thermal energy plant comprising a light absorber comprising nanoparticles in a host material which is transparent in an absorbing range of the light absorber and where the nanoparticles exhibit plasmonic resonances within the absorbing range of the light absorber, wherein the dispersion of the nanoparticles in the host material is controlled in such a way that the mean distance between said nanoparticles is lower than the wavelengths of light in the absorbing range of the light absorber for generating near field radiation interactions between said nanoparticles, where the size and the distribution of the nanoparticles is chosen to obtain a cutoff wavelength, where light of higher wavelength than the cutoff wavelength is less absorbed than light at shorter wavelengths with respect to the cutoff wavelength reducing losses due to infrared radiation of the absorber. 
     
     
         2 . Solar thermal receiver absorber as to  claim 1 , where the absorbing range is in the visible range and where said nanoparticles are metallic nanoparticles. 
     
     
         3 . Solar thermal receiver absorber as to  claim 2 , where said metallic nanoparticles are made of silver and/or of gold. 
     
     
         4 . Solar thermal receiver absorber as to  claim 1 , where the absorbing range is in the infrared range and where said nanoparticles are polarized polar nanoparticles. 
     
     
         5 . Solar thermal receiver absorber as to  claim 1 , where said nanoparticles are at least of a first material and a second material different from the first material. 
     
     
         6 . Solar thermal receiver absorber as to  claim 1 , where said nanoparticles comprise nanoparticles of a first mean size and nanoparticles of a second mean size, different from the first mean size. 
     
     
         7 . Solar thermal receiver as to  claim 1 , where the mean radius of said nanoparticles is less than 100 nm. 
     
     
         8 . Solar thermal receiver as to  claim 1 , where said nanoparticles are of spherical shape. 
     
     
         9 . Solar thermal receiver as to  claim 1 , where said light absorber is arranged as a layer having a backside in contact with a heat conducting medium. 
     
     
         10 . A light absorber for use in a solar thermal receiver, the light absorber comprising:
 a host material transparent in an absorbing range of the light absorber; and   nanoparticles dispersed in said host material such that a mean distance between said nanoparticles is less than a wavelength of light in the absorbing range of the light absorber such that the nanoparticles generate near field radiation interactions between the nanoparticles and wherein:
 said nanoparticles exhibit plasmonic resonances within the absorbing range of the light absorber; and 
 the size and the distribution of the nanoparticles is chosen to obtain a cutoff wavelength such that light having a wavelength longer than the cutoff wavelength is less absorbed than light having a wavelength which is shorter than the cutoff wavelength. 
   
     
     
         11 . The light absorber of  claim 10  wherein the reducing the characteristic of said host material and nanoparticles are selected to reduce losses due to infrared radiation of the absorber. 
     
     
         12 . The light absorber of  claim 10  wherein the absorbing range is in the visible range and where said nanoparticles are provided as metallic nanoparticles. 
     
     
         13 . The light absorber of  claim 12  wherein said metallic nanoparticles are made of silver and/or of gold. 
     
     
         14 . The light absorber of  claim 10  where the absorbing range is in the infrared range and where said nanoparticles are polarized polar nanoparticles. 
     
     
         15 . The light absorber of  claim 10  wherein said nanoparticles are at least of a first material and a second material different from the first material. 
     
     
         16 . The light absorber of  claim 10  wherein said nanoparticles comprise nanoparticles of a first mean size and nanoparticles of a second mean size, different from the first mean size. 
     
     
         17 . The light absorber of  claim 10  wherein the mean radius of said nanoparticles is less than 100 nm. 
     
     
         18 . The light absorber of  claim 10  wherein said nanoparticles are of spherical shape. 
     
     
         19 . The light absorber of  claim 10  wherein said light absorber is arranged as a layer having a backside in contact with a heat conducting medium.