The present disclosure relates to an improved open vertical display case (OVDC) which utilizes radiant cooling to cool and/or maintain food products at a target temperature. The radiant cooling is performed using a plurality of piping routed through the walls and containing a first refrigerant stream. The plurality of piping may be cooled using a refrigeration circuit. In some embodiments, a phase change material may be used for thermal energy storage and positioned between the plurality of piping and the refrigeration circuit. In some embodiments, the refrigeration circuit may be connected to heating ventilation and air conditioning (HVAC) systems and water heating systems within the building.

Examples of heat exchanger systems for active radiative cooling are described. In one example, the system includes a heat exchanger and a spectrally selective surface material on at least one surface of the heat exchanger. The spectrally selective surface material exhibits high reflectivity at shorter wavelengths and high emissivity at longer wavelengths. The system can also include an active cooling system in some cases to actively transfer heat to the heat exchanger. The use of spectrally selective surfaces that operate at temperatures exceeding that of the outdoor ambient for which convective losses augment radiation losses have advantages over passive cooling, such as but not limited to: providing a better match to cooling loads, reducing the heat rejection surface area required to achieve a desired cooling rate, and increasing the heat transferred to deep space through the atmospheric window so as to simultaneously cool infrastructure, devices, buildings, and Earth.

A coating including a relatively thin visible-absorptive layer atop a relatively thick non-absorptive, solar-scattering underlayer. The thin top layer enables efficient absorption of appropriate visible wavelengths to show specific colors, and minimizes absorption in the infrared radiation in sunlight due to its relatively small thickness. Meanwhile, the bottom layer maximizes the backscattering of infrared light without absorption to reduce solar heating.

Systems according to the present disclosure provide one or more surfaces that function as power radiating surfaces for which at least a portion of the radiating surface includes or is composed of “fractal cells” placed sufficiently closed close together to one another so that a surface wave causes near replication of current present in one fractal cell in an adjacent fractal cell. The fractal cells may lie on a flat or curved sheet or layer and be composed in layers for wide bandwidth or multibandwidth transmission. The area of a surface and its number of fractals determines the gain relative to a single fractal cell. The boundary edges of the surface may be terminated resistively so as to not degrade the cell performance at the edges. The fractal plasmonic surfaces can be utilized to facilitate electrical conduction with lower ohmic resistance than would otherwise be possible in the absence of the fractal plasmonic surface(s) at the same temperature.

An optical refrigerator for cooling an infrared detector or sensor, that includes a laser radiation source, a cooling crystal for receiving laser radiation from the source and to be cooled, an element to be cooled, and a thermal link in heat exchange between the crystal and the element to be cooled, in order to transfer frigories from the crystal to the element to be cooled. The thermal link comprises two plates having respective first ends in heat exchange with two distinct surfaces of the crystal, respectively, the two plates having second ends in heat exchange with the element to be cooled.

A double or multi-layer apparatus or device for optical anti-Stokes cooling of object surfaces. The apparatus comprises at least one bottom layer, which is configured to respond in anti-Stokes fluorescence upon absorption of electromagnetic radiation and at least one top layer, which is overlaid on the bottom layer and configured to filter the electromagnetic radiation and transmit selected spectral band of the electromagnetic radiation to the bottom layer. The active cooling does not depend on the coherent nature of the radiation, which enables the usage of incoherent solar radiation as the active cooling input power source. The cooling technology of the invention is suitable for small and large scales and practically for any object with surface on which the layer substance can be applied or overlaid, e.g., roof, wall, car, ship, tent, clothing, etc.

A passive cooler of the disclosure includes a thermal emitter having a substrate and a coating disposed on at least a portion of a first side of the substrate. The cooler has a beam guide made from a material having a high absorption to solar wavelengths and high reflectance at mid-infrared wavelengths. The beam guide is configured such that at least a portion of incident light is acted on by the beam guide before reaching the thermal emitter. In some embodiments, the beam guide has a graded optical index.

An optical refrigeration system that includes a heatlink that is formed by textured crystals that are matched in coefficient of thermal expansion (CTE) to the yttrium lithium fluoride (YLF) cooling crystal, and shaped in geometries that result in very low heat producing losses (HPL). The optical refrigeration system may further include a mirror that is made of a semiconductor-material.

An apparatus and method of indirectly cooling an optomechanical resonator, comprising impinging a laser on an optomechanical resonator attached to a substrate, wherein the optomechanical resonator comprises a cantilever, a cooling end of the cantilever, having a cooling end comprising a laser-induced cooling element, an attachment end of the cantilever, attached to a substrate, and wherein the laser has a peak wavelength in the near-infrared band.

A material may be included in a cooling film or cooling panel to achieve cooling even under direct solar irradiation. The material includes one or more constituent materials and an outer surface configured to interact thermally with the atmosphere and with solar radiation. The material exhibits an emissivity of at least 0.8 in spectral range of 5 μm to 15 μm, an ultraviolet reflectivity of at least 0.5 in the spectral range of 275 nm to 375 nm, an ultraviolet absorptivity of at least 0.75 in the spectral range of 275 nm to 375 nm, or a combination thereof. A cooling film, or cooling panel, may be affixed to an exterior surface of a vehicle, structure, or system to provide cooling even under direct solar irradiance.