The present invention provides a solar absorber incorporated bilayer foam solar evaporator for seawater and wastewater purification including a plurality of solar absorbers partially incorporated into a porous polymer framework and partially forming a thermal insulation layer proximal to solar irradiation. In particular, low-cost commercially available B.sub.4C powders are embedded into a porous polymer foam in a one-pot method to form a scaffold of boron carbide bilayer foam (BCBF) with good hydrophilic wettability, heat-shielding, and solar-thermal conversion. The boron carbide bilayer foam (BCBF) of the present invention enables a high cost-performance seawater desalination and wastewater purification at a high evaporation rate of 2.8 kg/m.sup.2/h with 93% solar evaporation efficiency under 1 sun illumination (or 1 kW/m.sup.2). The present invention thereby provides an excellent and cost-effective solar evaporator tool for industrial-level water purification. Following the present method to prepare the BCBF solar evaporator, the fabrication cost can be as low as 3.6 $/m.sup.2.

Generally, the present disclosure of embodiments of Disclosed is a construction element of a null-energy system. Such a construction element can include a body on which the construction element can further include a porous material compartment with porous material to store water and evaporate the stored water outwards from the porous material through a holding layer on the opposite side of the porous material compartment to the body. The disclosure relates also to a null-energy system using a construction element of null-energy system as embodied therein.

Generally, the present disclosure of embodiments of Disclosed is a construction element of a null-energy system. Such a construction element can include a body on which the construction element can further include a porous material compartment with porous material to store water and evaporate the stored water outwards from the porous material through a holding layer on the opposite side of the porous material compartment to the body. The disclosure relates also to a null-energy system using a construction element of null-energy system as embodied therein.

The receiver (25,50,100,120) according to the invention is provided with the heating area (26) for heating a heat-transporting medium, which has an optical opening (3) for sunlight, an absorber (27, 51) absorbing the sunlight arranged within the path of the incidental sunlight and with a transport arrangement for the transport of the medium through the heating area, wherein the absorber (27, 52) is designed as a blackbody radiation arrangement with reduced convection and the transport arrangement (29) for the transport of a gas is designed as a heat-transporting medium. By means of this, the receiver can be designed in a simpler and more reliable manner.

The receiver (25,50,100,120) according to the invention is provided with the heating area (26) for heating a heat-transporting medium, which has an optical opening (3) for sunlight, an absorber (27, 51) absorbing the sunlight arranged within the path of the incidental sunlight and with a transport arrangement for the transport of the medium through the heating area, wherein the absorber (27, 52) is designed as a blackbody radiation arrangement with reduced convection and the transport arrangement (29) for the transport of a gas is designed as a heat-transporting medium. By means of this, the receiver can be designed in a simpler and more reliable manner.

Solar thermal devices are formed from a block of wood, where the natural cell lumens of the wood form an interconnected network that transports fluid or material therein. The block of wood can be modified to increase absorption of solar radiation. Combining the solar absorption effects with the natural transport network can be used for various applications. In some embodiments, heating of the modified block of wood by insolation can be used to evaporate a fluid, for example, evaporating water for extraction, distillation, or desalination. In other embodiments, heating of the modified block of wood by insolation can be used to change transport properties of a material to allow it to be transported in the interconnected network, for example, heating crude oil to adsorb the oil within the block of wood.

Solar thermal devices are formed from a block of wood, where the natural cell lumens of the wood form an interconnected network that transports fluid or material therein. The block of wood can be modified to increase absorption of solar radiation. Combining the solar absorption effects with the natural transport network can be used for various applications. In some embodiments, heating of the modified block of wood by insolation can be used to evaporate a fluid, for example, evaporating water for extraction, distillation, or desalination. In other embodiments, heating of the modified block of wood by insolation can be used to change transport properties of a material to allow it to be transported in the interconnected network, for example, heating crude oil to adsorb the oil within the block of wood.

An interconnected open-pore 2.5D Cu/CuO foam-based photothermal evaporator capable of achieving a high evaporation rate of 4.1 kg m.sup.-2 h.sup.-1 under one sun illumination by exposing one end of the planar structure to air is disclosed. The micro-sized open-pore structure of Cu/CuO foam allows it to trap incident sunlight, and the densely distributed blade-like CuO nanostructures effectively scatter sunlight inside pores simultaneously. The inherent hydrophilicity of CuO and capillarity forces from the porous structure of Cu foam continuously supply sufficient water. Moreover, the doubled working sides of Cu/CuO foam enlarge the exposure area enabling efficient vapor diffusion. The feasible fabrication process and the combined structural features of Cu/CuO foam offer new insight into the future development of solar-driven evaporators in large-scale applications with practical durability.

An interconnected open-pore 2.5D Cu/CuO foam-based photothermal evaporator capable of achieving a high evaporation rate of 4.1 kg m.sup.-2 h.sup.-1 under one sun illumination by exposing one end of the planar structure to air is disclosed. The micro-sized open-pore structure of Cu/CuO foam allows it to trap incident sunlight, and the densely distributed blade-like CuO nanostructures effectively scatter sunlight inside pores simultaneously. The inherent hydrophilicity of CuO and capillarity forces from the porous structure of Cu foam continuously supply sufficient water. Moreover, the doubled working sides of Cu/CuO foam enlarge the exposure area enabling efficient vapor diffusion. The feasible fabrication process and the combined structural features of Cu/CuO foam offer new insight into the future development of solar-driven evaporators in large-scale applications with practical durability.

Omnivorous solar thermal thrusters and adjustable cooling structures are disclosed. In one aspect, a solar thermal rocket engine includes a solar thermal thruster configured to receive solar energy and one or more propellants, and heat the one or more propellants using the solar energy to generate thrust. The solar thermal thruster is further configured to use a plurality of different propellant types, either singly or in combination simultaneously. The solar thermal thruster is further configured to use the one or more propellants in both liquid and gaseous states. Related structures can include valves and variable-geometry cooling channels in thermal contact with a thruster wall.