Polymer-based selective radiative cooling structures are provided which include a selectively emissive layer of a polymer or a polymer matrix composite material. Exemplary selective radiative cooling structures are in the form of a sheet, film or coating. Also provided are methods for removing heat from a body by selective thermal radiation using polymer-based selective radiative cooling structures, and a cold collection system comprising a plurality of the polymer-based selective radiative cooling structures.

A system and method for operating a selective emitter is provided. One embodiment comprises a heat sink that absorbs heat from an ambient environment, a heat pipe comprising a cooling portion thermally coupled to the heat sink, a wick portion and a heat dissipation portion, and a selective emitter that is thermally coupled to the cooling portion of the heat pipe. The selective emitter converts absorbed heat into radiative energy that is emitted out through the Earth's atmosphere.

Various aspects as described herein are directed to a radiative cooling apparatuses and methods for cooling an object. As consistent with one or more embodiments, a radiative cooling apparatus includes an arrangement of a plurality of different material located at different depths along a depth dimension relative to the object. The plurality of different material includes a solar spectrum reflecting portion configured and arranged to suppress light modes, thereby inhibiting coupling of the incoming electromagnetic radiation, of at least some wavelengths in the solar spectrum, to the object at a range of angles of incidence relative to the depth dimension. Further, the plurality of material includes a thermally-emissive arrangement configured and arranged to facilitate, simultaneously with the inhibiting coupling of the incoming electromagnetic radiation, the thermally-generated electromagnetic emissions from the object at the range of angles of incidence and in mid-IR wavelengths.

A mechano-caloric heat pump includes a mechano-caloric stage, an elongated lever arm pivotable about a point, and a motor is operable to rotate a cam. The elongated lever arm is coupled to the mechano-caloric stage proximate a first end portion of the elongated lever arm and to the cam proximate a second end portion of the elongated lever arm such that the motor is operable to stress the mechano-caloric stage via pivoting of the elongated lever arm as the cam rotates.

A mechano-caloric heat pump includes a mechano-caloric stage, an elongated lever arm pivotable about a point, and a motor is operable to rotate a cam. The elongated lever arm is coupled to the mechano-caloric stage proximate a first end portion of the elongated lever arm and to the cam proximate a second end portion of the elongated lever arm such that the motor is operable to stress the mechano-caloric stage via pivoting of the elongated lever arm as the cam rotates.

A two-phase cooling system with flow boiling, characterized in that a closed hydraulic circuit apparatus of a heat transfer refrigerating fluid is provided, including: a pump for a refrigerating fluid which, at least in some stretches of the circuit, is two-phase liquid-vapor or multi-phase; a heat sink-evaporator configured to transfer heat by conduction from a component to be cooled to the refrigerating fluid; a condenser, capable of condensing the vapor which develops on the evaporator while simultaneously dissipating the heat given by the refrigerating fluid both by conduction, convection and radiation and by condensation into the environment; a tank which also acts as an expansion vessel, or a tank and an expansion vessel which are distinct and connected to each other; and a plurality of sensors, including flow rate, pressure and temperature sensors and an electronic control system of the pump.

A refrigeration system includes a heat exchanger configured to place a cooling fluid in a heat exchange relationship with a working fluid, a free-cooling circuit having a pump configured to circulate the working fluid through the heat exchanger and a condenser, a flow control valve configured to control a flow rate of the working fluid to the condenser, a condenser bypass valve configured to control a flow rate of the working fluid that bypasses the condenser, and a controller configured to adjust a position of the flow control valve, a position of the condenser bypass valve, a speed of a fan of the condenser, a speed of the pump, and a temperature of a heater based on an ambient temperature, a temperature of the working fluid leaving the condenser, the position of the flow control valve, the position of the condenser bypass valve, or a combination thereof.

Heat transfer devices and systems are provided for the rapid cooling of pulsed high-powered, high-flux devices using flash boiling. Such devices comprise at least two fluidly connected chambers and a heat exchanger in thermal communication with a heat source. A flash boiling event is actively triggered at a location close to the heat source by rapid depressurization of the chamber containing a multi-phase coolant. This boiling process allows for high heat transfer rates from the heat source into the chambers due to the latent heat of vaporization, which results in the rapid cooling of the heat source. A porous medium may also be positioned within a chamber of the device to enhance boiling nucleation and extended surface heat transfer. Methods of rapidly cooling pulsed heat sources are also provided using the devices and systems hereof.

The present disclosure relates to a technical idea of reducing the surface temperature of a material or temperature under a material by emitting heat under a device to the outside by absorbing and emitting long-wavelength infrared light corresponding to the wavelength range of the atmospheric window while minimizing absorption of light of the solar spectrum. More particularly, the present disclosure relates to a technology for providing a radiative cooling device having a multilayer structure that is capable of increasing sunlight reflection through differences in the refractive indexes of the device-forming materials while performing selective emission over the wavelength range of the atmospheric window using a radiative cooling device having a multilayer structure composed of polymers and inorganic materials.

A thermally driven elastocaloric system and a method for generating at least one of a heating potential and a cooling potential are provided. The thermally driven elastocaloric system includes a first shape memory alloy (SMA) member, a second shape memory alloy (SMA) member, and a connection mechanism configured between the distal end of the first SMA member and the distal end of the second SMA member. The connection mechanism is configured to transfer a force between the first SMA member and the second SMA member. The transfer of a compressive force to an SMA member may generate a heating potential in the SMA member, and the transfer of a tensile force to an SMA member may generate a cooling potential in the SMA member. Whether a compressive force or a tensile force is transferred may be dependent on whether heat is transferred to or from a SMA member.