A numerical method to compute a two-dimensional hypersonic flowfield that is weakly ionized and in thermochemical nonequilibrium has been developed. Such a flowfield is described by coupled partial differential equations for the conservation of species mass, mass-averaged momentum, vibrational energy of each diatomic species, electron energy, and total energy. The steady-state solution to these fully coupled equations has been obtained for a gas composed of seven chemical species and characterized by six temperatures using an implicit Gauss-Seidel line relaxation technique. The computed electron number densities in the flowfield of a sphere cone compare well with experimental results.

Computation of weakly ionized hypersonic flows in thermochemical nonequilibrium

A power generation system includes at least one turbine system. The turbine system includes a compressor section comprising at least one stage, configured to supply a compressed oxidant and a combustion chamber configured to combust the compressed oxidant and a fuel stream comprising carbon-based fuels and to generate a hot flue gas. The turbine system further includes an expander section having an inlet for receiving the hot flue gas comprising at least two stages. The two stages include a high-pressure expander configured to generate an expanded exhaust gas rich in CO 2 . The high-pressure expander fluidly coupled to a low-pressure expander configured to generate a final exhaust and electrical energy. A CO 2 separation system is fluidly coupled to the high-pressure expander for receiving the expanded exhaust gas from the high-pressure expander and providing a CO 2 lean gas that is then fed to the low-pressure expander.

Systems and methods for power generation with carbon dioxide isolation

The objective of this paper is to provide a succinct review of past and current research in developing wave rotor technology. This technology has shown unique capabilities to enhance the performance and operating characteristics of a variety of engines and machinery utilizing thermodynamic cycles. Although there have been a variety of applications in the past, this technology is not yet widely used and is barely known to engineers. Here, an attempt is made to summarize both the previously reported work in the literature and ongoing efforts around the world. The paper covers a wide range of wave rotor applications including the early attempts to use wave rotors, its successful commercialization as superchargers for car engines, research on gas turbine topping, and other developments. The review also pays close attention to more recent efforts: utilization of such devices in pressure-gain combustors, ultra-micro gas turbines, and water refrigeration systems, highlighting possible further efforts on this topic. Observations and lessons learnt from experimental studies, numerical simulations, analytical approaches, and other design and analysis tools are presented.

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A Review of Wave Rotor Technology and Its Applications

Methods and systems for low emission power generation in hydrocarbon recovery processes are provided. One system includes integrated pressure maintenance and miscible flood systems with low emission power generation. An alternative system provides for low emission power generation, carbon sequestration, enhanced oil recovery (EOR), or carbon dioxide sales using a hot gas expander and external combustor. Another alternative system provides for low emission power generation using a gas power turbine to compress air in the inlet compressor and generate power using hot carbon dioxide laden gas in the expander. Other efficiencies may be gained by incorporating heat cross-exchange, a desalination plant, co-generation, and other features.

Low emission power generation and hydrocarbon recovery systems and methods

Power plants and process for lowering CO2 emissions generally includes extracting a portion of the recirculated CO2-rich flue gas mid-way through the compression pathway of a gas turbine and removing the CO2 in a separation unit. The remaining portion of the CO2 rich flue gas (i.e., the portion of the recirculated flue gas that was not fed to the separation unit) is mixed with fresh air coming from an additional compressor-expander and then fed back to the compression pathway. As a result, flue gas recirculation increases the CO2 concentration within the working fluid, leading to an additional increase in CO2 partial pressure. As the concentration and partial pressure of CO2 is increased, a lower energy penalty is observed to remove the CO2. Moreover, a reduced volume is fed to the CO2 separation unit during operation. Consequently, the size of the separation equipment can be reduced as well as the energy required for the separation process.

Power plants that utilize gas turbines for power generation and processes for lowering co2 emissions

A turbine engine system and a method for using the turbine engine system that includes at least one low-pressure compressor, at least one high-pressure compressor, at least one low-pressure turbine, and at least one high-pressure turbine. In addition, the turbine engine system includes an absorption refrigeration system that is used to pre-cool an air-gas mixture before it enters the high-pressure compressor. As such, the pre-cooled mixture is easier to compress, thereby increasing the thermal efficiency of the turbine engine. Additionally, the exhaust heat from the air-gas mixture that is pre-cooled may be used to drive the absorption refrigeration system. Lastly, water, may be extracted from the evaporator of the absorption refrigeration cycle.

Combined cooling and power plant with water extraction

A computational method to analyze the flow in wave rotors and their adjoining ducts has been formulated and implemented. The method solves the flow within the rotor in the absolute frame of reference. The approach rigorously treats of the duct-rotor interface, allowing for the blade-induced work due to an initial non-uniform angle of attack. Several cases were simulated, showing that for off-design conditions the port flows are significantly non-uniform, contrary to conventional models. The calculations also predict a significant region of recirculation in the high pressure duct. The new computational approach shows promise for further development. Introduct ion to Wave Rotors Wave rotors are devices which utilize unsteady wave processes to effect work exchange between two fluid streams, a process thermodynamically equivalent to that of a turbocompressor. As in a turbocompressor, the expanding and the compressing fluid streams enter and leave the device via ducts in which the flow is substantially steady. Unsteady processes within the wave rotor cause the expanding stream to perform work on the secondary stream. These unsteady processes are generated in a series of cells arranged longitudinally around the periphery of a rotor, reminiscent of a Gatling gun. The rotor is rotated to cause valving action, exposing the cell ends to the fluid ports or blank wall. The timing is such that the moving compression and expansion waves generated by these time-dependent boundary conditions produce the desired pressure changes for each stream. The process in each cell is cyclic, since the boundary conditions are periodic as the rotor makes a revolution. This means 1) each time the cell is at a particular angular position, it must have the same distribution of gas properties along its length, and 2) every cell must go through the same cycle, with only aphase difference from its neighbors. The consequence is that the wave pattern, although unsteady in the frame of reference of the cell, is almost steady as viewed by a stationary observer. The small unsteadiness is “jitter” as the cell walls pass. In the limit of infinitesimal cell widths Copyright 0 1 9 9 3 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. d’ ‘d’ (infinite blading), the wave rotor flow is steady. The present paper is a description of a method of exploiting that fact to create a powerful wave rotor analysis technique. Wave rotors are not new, having been successfully used since the late 1950s in scientific and commercial applications (the only commercially-produced wave rotor is the Comprex supercharger for automotive and truck engines’). The Wave Superheater built in the late 1950s by Cornell Aeronautical Laboratories was a type of wave rotor; it remains today the only steady-flow uncontaminated-air hypersonic test facility ever built, capable of generating air at 5000 K and 100atm2. Current interest in wave rotors centers on aerospace applications, primarily their use as topping units for gas turbine engines3. In this application, the compressing stream would be air (from the conventional compressor), and the expanding stream would be hot gas from the combustor. The compressing stream leaves the wave rotor and enters the combustor; the expanding stream exit supplies the conventional turbine. Experimental and analytical studies are currently under way at the NASA Lewis Research Center aimed at establishing a reliable methodology for wave rotor design. The chief advantage to using a wave rotor as a topping unit is increased maximum cycle temperature. The rotating element of a wave rotor is alternately exposed to the hot gas and the full flow of cooler air. Thus, the rotor material temperature establishes an intermediate level (analogous to the cylinder head temperature in an automobile engine). This 100% cooling air effect is expected to allow burner exit temperatures hundreds of degrees higher than current gas turbine engines, even using existing materials. Current and envisioned calculational methods for wave rotors fall into two categories: 1) design codes, which solve the I-D Euler equation for time-dependent flow4, and 2) 2-D time-dependent CFD codes. The second approach is numerically intensive and would not be cost-effective for design. However, the design codes now in use solve the hyperbolic PDE in a single tube,

Direct boundary value solution of wave rotor flow fields

Efficiency and gasdynamic analysis of two-phase mixtures in supersonic nozzles with inter-phase heat transfer and slip

Blade vortex interaction noise is a problematic and dominant component of rotor noise. Plasma actuators strategically placed at the tip of the rotor blades can reduce the strength of the tip vortic...

William E. Lear

Papers

Combined cooling and power plant with water extraction

Direct boundary value solution of wave rotor flow fields

Efficiency and gasdynamic analysis of two-phase mixtures in supersonic nozzles with inter-phase heat transfer and slip

Fundamental investigation using active plasma control to reduce blade–vortex interaction noise:

Analysis of the accuracy of wave rotor boundary conditions using a novel computational method