A constant density heat exchanger is provided. The constant density heat exchanger includes a housing extending between a first end and a second end and defining a chamber having an inlet and an outlet. A first flow control device is positioned at the inlet of the chamber and movable between an open position in which a working fluid is permitted into the chamber and a closed position in which the working fluid is prevented from entering the chamber. A second flow control device is positioned at the outlet of the chamber and movable between an open position in which the working fluid is permitted to exit the chamber and a closed position in which the working fluid is prevented from exiting the chamber. A heat exchange fluid imparts thermal energy to the volume of working fluid held at constant density within the chamber by the first and second control devices.

A heat pipe is provided having a hollow body defining an interior vapor space, evaporator and condenser regions, a wick structure lining an inner wall of the hollow body, and a working fluid disposed in the hollow body, wherein a path for the working fluid in liquid state extends from the condenser region toward the evaporator region or wherein the wick structure extends along a direction from a first end of the hollow body toward the second end, and wherein the wick structure includes first and second regions that extend along the path or direction and that each have wick particles defining respective pore sizes that are different from one another.

A heat-dissipation substrate having a gradient sputtered structure includes at least two layers. A first layer is a heat-dissipation base layer, and a second layer is a gradient sputtered layer that is bonded onto the heat-dissipation base layer by gradient sputtering. An outermost surface layer of the gradient sputtered layer is a functional layer, and the gradient sputtered layer contains a main component of the heat-dissipation base layer and that of the functional layer. A percentage of the main component of the functional layer contained in the gradient sputtered layer monotonically increases or strictly monotonically increases along a direction from the heat-dissipation base layer toward the functional layer, and a percentage of the main component of the heat-dissipation base layer contained in the gradient sputtered layer monotonically increases or strictly monotonically increases along a direction from the functional layer toward the heat-dissipation base layer.

An energy conversion apparatus may include an engine assembly, such as a monolithic engine assembly. The engine assembly may include a first monolithic body segment and a plurality of second monolithic body segments directly coupled or directly couplable to the first monolithic body segment. The first monolithic body segment may define a combustion chamber and a recirculation pathway in fluid communication with the combustion chamber. The recirculation pathway may be configured to recirculate combustion gas through the combustion chamber. The plurality of second monolithic body segments may respectively define at least a portion of a piston chamber and a plurality of working-fluid pathways fluidly communicating with the piston chamber.

An energy conversion apparatus may include an engine assembly, such as a monolithic engine assembly. The engine assembly may include a first monolithic body segment and a plurality of second monolithic body segments directly coupled or directly couplable to the first monolithic body segment. The first monolithic body segment may define a combustion chamber and a recirculation pathway in fluid communication with the combustion chamber. The recirculation pathway may be configured to recirculate combustion gas through the combustion chamber. The plurality of second monolithic body segments may respectively define at least a portion of a piston chamber and a plurality of working-fluid pathways fluidly communicating with the piston chamber.

A heat conduction device includes a heat source portion, a temperature control surface, and heat transfer portions. The heat source portion is configured to generate at least hot heat or cold heat. The temperature control surface is sectioned into a plurality of temperature control sections, and at least some of the plurality of temperature control sections are disposed away from the heat source portion. The plurality of heat transfer portions connect the heat source portion and the plurality of the temperature control sections to transfer heat between the heat source portion and the plurality of temperature control sections. The plurality of temperature control sections are separated from each other based on a distance from the heat source portion.

A heat conduction device includes a heat source portion, a temperature control surface, and heat transfer portions. The heat source portion is configured to generate at least hot heat or cold heat. The temperature control surface is sectioned into a plurality of temperature control sections, and at least some of the plurality of temperature control sections are disposed away from the heat source portion. The plurality of heat transfer portions connect the heat source portion and the plurality of the temperature control sections to transfer heat between the heat source portion and the plurality of temperature control sections. The plurality of temperature control sections are separated from each other based on a distance from the heat source portion.

The disclosure relates to a heat transfer assembly for a rotary regenerative heat exchanger. The assembly includes a rotor arranged between at least two separated fluid flow passages passing flow axially through the rotor, where each flow passage is connected to a sector part of the rotor. The assembly further includes a plurality of channels in the rotor for flowing a fluid through the rotor, each of the channels is enclosed by heat transfer and heat accumulating surfaces in the rotor, and the heat transfer and heat accumulating surfaces of the channels are made in a material providing an average axial thermal conductivity less than 100 W/mK arranged to reduce the Longitudinal Heat Conductivity of the rotor.

The disclosure relates to a heat transfer assembly for a rotary regenerative heat exchanger. The assembly includes a rotor arranged between at least two separated fluid flow passages passing flow axially through the rotor, where each flow passage is connected to a sector part of the rotor. The assembly further includes a plurality of channels in the rotor for flowing a fluid through the rotor, each of the channels is enclosed by heat transfer and heat accumulating surfaces in the rotor, and the heat transfer and heat accumulating surfaces of the channels are made in a material providing an average axial thermal conductivity less than 100 W/mK arranged to reduce the Longitudinal Heat Conductivity of the rotor.

Solid-state thermoclines with internal baffle structures are in used in place of heat exchangers in a closed thermodynamic cycle power generation or energy storage system, such as a closed Brayton cycle system. The baffles limit the conductive and/or radiative transfer of heat between a solid thermal medium within different zones defined by the baffle structures.