42 results about "Low emittance" patented technology

The emittance value is a measure of an amount of energy expelled from a given surface area relative to a black-body reference. Depending on the specific coating a change in the emittance value is actively or passively effected. There are known active variable emittance thermal control coatings. However, such coatings are actually panels housing a mixture of both high and low emissivity materials that are electrically manipulated to control the emittance value of the panel. These “coatings” are classified as either electrochromic or electrophorectic. Both electrochromic and electrophorectic coatings require an applied voltage to cause a change in the emittance value of the coating. By contrast, aspects of the present invention do not include active variable emittance thermal control coatings. Aspects of the present invention do include passive variable emittance thermal control coatings and materials. In accordance with aspects of the present invention “passive” means that the variable emittance value changes in response to changes in the environment without active control (e.g. neither a voltage nor a current is applied). More specifically, in accordance with one aspect of the invention a passive variable emittance thermochromic material is provided that has a relatively low emittance value at low temperatures and a relatively high emittance value at high temperatures.

Designs for constructing a surface with variable emittance are described. This is achieved by making a surface where the emissivity varies on a scale smaller than the resolution of a thermal imager viewing the surface. One design utilizes many cylindrical surfaces with their axis parallel and their surfaces nearly in contact. Individual cylinders have the property that when rotated to zero degrees they show a surface with an emissivity of one and when rotated to 180 degrees display a surface with an emissivity of zero. At intermediate angles of rotation a sensor that could resolve individual cylinders would see alternate lines with high and low emittance but a sensor unable to resolve individual cylinders sees a surface with an emittance that depends on the angle the cylinders are rotated. Variable emittance surfaces are expected to be useful for controlling target signature and for making spectral reflectivity measurements using a hyper-spectral radiometer.

A photoelectron linear accelerator for producing a low emittance polarized electric beam. The accelerator includes a tube having an inner wall, the inner tube wall being coated by a getter material. A portable, or demountable, cathode plug is mounted within said tube, the surface of said cathode having a semiconductor material formed thereon.

A reflective insulation layer is provided for a structure. The structure includes a wall and spaced-apart strips which extend along the wall from a top portion of the wall to a bottom portion of the wall. The reflective insulation layer includes a low emittance layer having first perforations, an intermediate low emittance layer having first perforations and an outer synthetic polymer layer having second perforations. Additionally, the reflective insulation layer includes a first expander spaced between the low emittance layer and the intermediate low emittance layer, to couple the low emittance layer to the intermediate low emittance layer and form a first air space. Additionally, the reflective insulation layer includes a second expander spaced between the intermediate low emittance layer and the outer synthetic polymer layer, to couple the intermediate low emittance layer to the outer synthetic polymer layer and form a second air space.

A solar thermal photovoltaic device, and method of forming same, includes a solar absorber and a spectrally selective emitter formed on either side of a thermally conductive substrate. The solar absorber is configured to absorb incident solar radiation. The solar absorber and the spectrally selective emitter are configured with an optimized emitter-to-absorber area ratio. The solar thermal photovoltaic device also includes a photovoltaic cell in thermal communication with the spectrally selective emitter. The spectrally selective emitter is configured to permit high emittance for energies above a bandgap of the photovoltaic cell and configured to permit low emittance for energies below the bandgap.

The invention discloses a self-adaptive thermal camouflage coating, which is located on a substrate, and is mainly formed by a vanadium dioxide coating, a tungsten-doped vanadium dioxide coating and a low-emissivity coating. A preparation method of the self-adaptive thermal camouflage coating provided by the invention comprises the steps of (1) preparing vanadium dioxide ink, tungsten-doped vanadium dioxide ink and low emissivity ink; (2) depositing the vanadium dioxide ink, the tungsten-doped vanadium dioxide ink and the low emissivity ink on the surface of the substrate through a spray ink printing method according to designed camouflage patterns, and obtaining a layer of self-adaptive thermal camouflage coating on the surface of the substrate. According to the self-adaptive thermal camouflage coating provided by the invention, the self-adaptive thermal camouflage coating is prepared by adopting vanadium dioxide nano-powder with a thermotropic infrared emittance characteristic, tungsten-doped vanadium dioxide nano-powder and low emissivity silver powder, so that the camouflage patterns can be changed with the temperature change accordingly, and an infrared camouflage effect is greatly improved.