A method for producing work is disclosed. The method includes increasing the pressure of a working fluid including carbon dioxide from a first pressure at least equal to a triple point pressure to a second pressure above the triple point pressure. The method also includes heating the working fluid, extracting mechanical work by expanding a first portion of the heated working fluid to a third pressure, supplying a second portion of the heated working fluid as a motive fluid to an ejector, increasing the pressure of the expanded working fluid by supplying the expanded working fluid to the ejector to combine with the motive fluid and form an output fluid at the fourth pressure, the fourth pressure at least equal to the triple point pressure of the working fluid. The method also includes refrigerating the output fluid to condense a vapor phase into a liquid phase.

A heat exchanger has: a first manifold assembly having a stack of plates; a second manifold assembly having a stack of plates; and a plurality of tubes extending from the first manifold assembly to the second manifold assembly. The plurality of tubes is a plurality groups of tubes. For each of the groups of the tubes: the tubes of the group have first ends mounted between plates of the first manifold assembly; and the tubes of the group have second ends mounted between plates of the second manifold assembly.

In a method of hybrid power generation in an environment with a gas pressure below the earth's atmospheric pressure, liquid water is extracted from a subsurface water ice deposit by pumping superheated-supercritical fluid heated by a heater through an extraction well into the subsurface water ice deposit in order to form a liquid water reservoir. Liquid water is pumped from the liquid water reservoir through the extraction well to the buffer tank. The liquid water is pumped from the buffer tank into a high pressure feeder system (HPFS) and a low pressure feeder system (LPFS), which are each also heated by the heater. The HPFS outputs supercritical water and the LPFS outputs flash steam into a combined injector and the mixture is injected into a turbine at near environmental pressure. This mixture explosively expands into superheated steam and passes through the turbine, powering an electrical generator.

A heat exchanger has arcuate inlet and outlet manifolds and a plurality of tube banks, each tube bank coupling one of the inlet manifold outlets to an associated one of the outlet manifold inlets. Each tube bank partially nests with one or more others of the tube banks and has: a first header coupled to the associated inlet manifold outlet and the associated the outlet manifold inlet; a second header; and a plurality of tube bundles each having a first end coupled to the associated first header and a second end coupled to the associated second header. A flowpath from the each inlet manifold outlet passes sequentially through flowpath legs formed by each of the tube bundles in the associated tube bank to exit the tube bank to the associated outlet manifold inlet.

In a method of hybrid power generation in an environment with a gas pressure below the earth's atmospheric pressure, liquid water is extracted from a subsurface water ice deposit by pumping superheated-supercritical fluid heated by a heater through an extraction well into the subsurface water ice deposit in order to form a liquid water reservoir. Liquid water is pumped from the liquid water reservoir through the extraction well to the buffer tank. The liquid water is pumped from the buffer tank into a high pressure feeder system (HPFS) and a low pressure feeder system (LPFS), which are each also heated by the heater. The HPFS outputs supercritical water and the LPFS outputs flash steam into a combined injector and the mixture is injected into a turbine at near environmental pressure. This mixture explosively expands into superheated steam and passes through the turbine, powering an electrical generator.

A system and method of generating electricity. A work string extends into a wellbore. A heat pump unit at a surface location circulates a working fluid through the work string to absorb heat from a formation surrounding the wellbore. A turbine generates a rotation from the working fluid that has absorbed the heat. A generator generates electricity from the rotation of the turbine. The electricity is transmitted to the surface location via an electrical cable.

Supercritical fluid systems and aircraft power systems are described. The systems include a compressor, a turbine, and a generator. A primary working fluid flow path has a primary working fluid that passes through the compressor, a separator, the turbine, and back to the compressor. A secondary working fluid flow path having a secondary working fluid that passes through the generator, the compressor, the separator, and back to the generator. The primary working fluid and the secondary working fluid are compressed and mixed within the compressor to form a mixture of the two fluids and the separator separates the mixture of the two fluids to direct the primary working fluid back to the turbine and the secondary working fluid to the generator.

A sublimation generator including a sublimation tank configured to receive ice including at least carbon dioxide. The sublimation generator also includes a first heat exchanger in thermal communication with the sublimation tank. The first heat exchanger being configured to expel heat from a coolant into the sublimation tank to sublimate the carbon dioxide into a gaseous state. The sublimation generator also includes a gas turbine generator fluidly connected to the sublimation tank and configured to receive the carbon dioxide in the gaseous state.

Methods and apparatus for cooling a surface on a flight vehicle and generating power include advancing the vehicle at a speed of at least Mach 3 to aerodynamically heat the surface. A first working fluid circulates through a first fluid loop that heats the first working fluid through a first heat intake thermally coupled to the surface and expands the first working fluid in a first thermal engine to generate a first work output. A second fluid loop has a second working fluid that receives heat from the first working fluid and a second thermal engine to generate a second work output. The first and second work outputs are operably coupled to first and second generators, respectively, to power primary or auxiliary systems on the flight vehicle.

Methods and apparatus for power generation and/or thermal management on a high speed flight vehicle include circulating a power generation loop working fluid through a power generation loop, which absorbs heat associated with the flight vehicle. A generator operably coupled to the power generation loop generates electrical power. Additionally, a heat transport loop working fluid may circulate through a heat transport loop to provide thermal management through heat transfer.