TN2020000136A1 - Composite material for a solar collector - Google Patents

Abstract

The invention relates to a composite material (V) comprising a carrier (1) consisting of aluminum, having an intermediate layer (2) situated on one side of the carrier (1), and having an optically effective multilayer system (3) applied on the intermediate layer (2) and comprising at least two dielectric and/or oxidic layers (4, 5), namely an upper layer (4) and an underlying light-absorbing layer (5), wherein the upper layer (4) is a dielectric layer having a refractive index n =< 2.0, and wherein a metallic layer (6) is arranged directly on the intermediate layer (2) below the at least two dielectric and/or oxidic layers (4,5). In order, with little technological outlay to provide a composite material (V) of this type having a particular suitability for absorbers of the low-temperature range, which material has a low stagnation temperature in conjunction with high efficiency and long term stability, it is proposed that the intermediate layer (2) and the optically effective multilayer system (3) are selected with regard to their optical properties and the layers (2, 4, 5, 6) are dimensioned in such a way that given a solar absorption (α) of at least 92 percent, not more than 20 percent to 35 percent of the solar radiation in a wavelength range (λ) of 1500 nm to 5000 nm is reflected and 25 percent to 90 percent of the solar radiation in a wavelength range (λ) of 5000 nm to 10000 nm is reflected, wherein in the wavelength range (λ) of 5000 nm to 10000 nm across the entire wavelength range (λ), a continuous rise in a wavelength-dependent reflectance (R) of the composite material (V) with the wavelength (λ) takes place.