Showing papers on "Gas compressor published in 2013"

Bleed air systems for use with aircrafts and related methods

Abstract: Bleed air systems for use with aircrafts and related methods are disclosed. An example apparatus includes a turbo-compressor including a compressor having a compressor inlet fluidly coupled to a low-pressure compressor of the aircraft engine and a compressor outlet fluidly coupled to a first system of an aircraft. The turbo-compressor also includes a turbine inlet fluidly coupled to a high-pressure compressor of the aircraft engine and a turbine outlet fluidly coupled to a second system of the aircraft.

Supercritical carbon dioxide Brayton cycle for concentrated solar power

Abstract: Supercritical carbon dioxide based Brayton cycle for possible concentrated solar power applications is investigated and compared with trans- and sub-critical operations of the same fluid. Thermal efficiency, specific work output and magnitude of irreversibility generation are used as some of the performance indicators. While the thermal efficiency increases almost linearly with low side pressure in the sub- and trans-critical cycles, it attains a maximum in the supercritical regime at 85 bar after which there are diminishing returns on increasing the low side pressure. It is also found that supercritical cycle is capable of producing power with a thermal efficiency of >30% even at a lower source temperature (820K) and accounting for foreseeable non-idealities albeit with a higher turbine inlet pressure (similar to 300 bar) which is not matched by a conventional sub-critical cycle even with a high source temperature of 978K. The reasons for lower efficiency than in an ideal cycle are extracted from an irreversibility analysis of components, namely, compressor, regenerator, turbine and gas cooler. Low sensitivity to the source temperature and extremely small volumetric flow rates in the supercritical cycle could offset the drawback of high pressures through a compact system.

System and method of improving emission performance of a gas turbine

Abstract: A power generation system (10) and method of generating power with reduced NO x emission includes a gas turbine system (15). The turbine system (15) includes a compressor (16) configured to receive a feed oxidant stream (14) and supply a compressed oxidant stream (18) to a combustion chamber (20) and an expander (24) configured to receive a discharge stream (22) from the combustion chamber (20) and generate an exhaust stream (30) comprising carbon dioxide and electrical energy. The system (10) further includes an exhaust gas recirculation system (54) configured to generate a recycle stream (52), wherein the recycle stream (52) is mixed with a fresh oxidant (12) to generate the feed oxidant stream (14). The exhaust gas recirculation system (54) includes an exhaust gas recirculation control loop (60) to control a pilot ratio (diffusion to total fuel ratio) based on received feedback related to combustion parameters. The control loop (60) is configured to control the pilot ratio required to keep NO x in its minimum ratios with improved flame stability.

Geared turbofan gas turbine engine architecture

Abstract: A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. A speed reduction device such as an epicyclical gear assembly may be utilized to drive the fan section such that the fan section may rotate at a speed different than the turbine section so as to increase the overall propulsive efficiency of the engine. In such engine architectures, a shaft driven by one of the turbine sections provides an input to the epicyclical gear assembly that drives the fan section at a speed different than the turbine section such that both the turbine section and the fan section can rotate at closer to optimal speeds providing increased performance attributes and performance by desirable combinations of the disclosed features of the various components of the described and disclosed gas turbine engine.

Methods and systems for boost control

Abstract: Methods and systems are provided for varying a proportion of compressed air recirculated to a compressor inlet from a location downstream of the compressor and upstream of a charge air cooler and a location downstream of the charge air cooler. A temperature-controlled compressor recirculation flow is used to reduce condensation from EGR being ingested into the compressor. The temperature-controlled compressor recirculation flow is also used to address compressor surge.

Pre-Stall Behavior of a Transonic Axial Compressor Stage Via Time-Accurate Numerical Simulation

Abstract: CFD calculations using high-performance parallel computing were conducted to simulate the pre-stall flow of a transonic compressor stage, NASA compressor Stage 35. The simulations were run with a full-annulus grid that models the 3D, viscous, unsteady blade row interaction without the need for an artificial inlet distortion to induce stall. The simulation demonstrates the development of the rotating stall from the growth of instabilities. Pressure-rise performance and pressure traces are compared with published experimental data before the study of flow evolution prior to the rotating stall. Spatial FFT analysis of the flow indicates a rotating long-length disturbance of one rotor circumference, which is followed by a spike-type breakdown. The analysis also links the long-length wave disturbance with the initiation of the spike inception. The spike instabilities occur when the trajectory of the tip clearance flow becomes perpendicular to the axial direction. When approaching stall, the passage shock changes from a single oblique shock to a dual-shock, which distorts the perpendicular trajectory of the tip clearance vortex but shows no evidence of flow separation that may contribute to stall.

Vehicle air-conditioning device

Abstract: This vehicle air-conditioning device is provided with: a blower (23) that blows out from a blowout opening into a vehicle cabin; a refrigeration cycle (40, 340) that circulates a refrigerant by means of an electric compressor; an interior heat exchanger (24, 26) that is provided to the refrigeration cycle, and that exchanges heat between the blown air resulting from the blower and the refrigerant; an inside/outside air adjustment device (22) that adjusts the fractions of inside air and outside air included in the blown air; and a blowing control unit (65) that, when the temperature difference between the outside air temperature (Tam) and the target temperature (Tao) of the blowout air blown out from the blowout opening is less than a predetermined value, causes the operation of the blower while the electric compressor is in a halted state, and controls the operation of the inside/outside air adjustment device in a manner so that air containing at least outside air is blown out into the vehicle cabin As a result, if Tao is a temperature close to Tam, the electric compressor is halted and air containing outside air is blown by means of the blower, and so the blowout air can be a temperature close to Tao while effecting a reduction in power consumption

Compound cycle engine

Abstract: A compound cycle engine having at least one rotary unit defining an internal combustion engine, a velocity turbine in proximity of each unit, and a turbocharger is discussed. The exhaust port of each rotary unit is in fluid communication with the flowpath of the velocity turbine upstream of its rotor. The rotors of the velocity turbine and of each rotary unit drive a common load. The outlet of the compressor of the turbocharger is in fluid communication with the inlet port of each rotary unit, and the inlet of the pressure turbine of the turbocharger is in fluid communication with the flowpath of the velocity turbine downstream of its rotor. A method of compounding at least one rotary engine is also discussed.

Experimental Investigation of Centrifugal Compressor Stabilization Techniques

Abstract: Results from a series of experiments to investigate techniques for extending the stable flow range of a centrifugal compressor are reported. The research was conducted in a high-speed centrifugal compressor at the NASA Glenn Research Center. The stabilizing effect of steadily flowing air-streams injected into the vaneless region of a vane-island diffuser through the shroud surface is described. Parametric variations of injection angle, injection flow rate, number of injectors, injector spacing, and injection versus bleed were investigated for a range of impeller speeds and tip clearances. Both the compressor discharge and an external source were used for the injection air supply. The stabilizing effect of flow obstructions created by tubes that were inserted into the diffuser vaneless space through the shroud was also investigated. Tube immersion into the vaneless space was varied in the flow obstruction experiments. Results from testing done at impeller design speed and tip clearance are presented. Surge margin improved by 1.7 points using injection air that was supplied from within the compressor. Externally supplied injection air was used to return the compressor to stable operation after being throttled into surge. The tubes, which were capped to prevent mass flux, provided 9.3 points of additional surge margin over the baseline surge margin of 11.7 points.

Startup and Operation of a Supercritical Carbon Dioxide Brayton Cycle

Abstract: Bechtel Marine Propulsion Corporation (BMPC) is testing a supercritical carbon dioxide (S-CO2) Brayton system at the Bettis Atomic Power Laboratory. The 100 kWe Integrated System Test (IST) is a two shaft recuperated closed Brayton cycle with a variable speed turbine driven compressor and a constant speed turbine driven generator using S-CO2 as the working fluid. The IST was designed to demonstrate operational, control and performance characteristics of an S-CO2 Brayton power cycle over a wide range of conditions.Initial operation of the IST has proven a reliable method for startup of the Brayton loop and heatup to normal operating temperature (570°F). An overview of the startup process, including initial loop fill and charging, and heatup to normal operating temperature is presented. Additionally, aspects of the IST startup process which are related to the loop size and component design which may be different for larger systems are discussed.Copyright © 2013 by ASME

Multi-Fidelity Simulation of a Turbofan Engine with Results Zoomed Into Mini-Maps for a Zero-D Cycle Simulation

Abstract: A Zero-D cycle simulation of the GE90-94B high bypass turbofan engine has been achieved utilizing mini-maps generated from a high-fidelity simulation. The simulation utilizes the Numerical Propulsion System Simulation (NPSS) thermodynamic cycle modeling system coupled to a high-fidelity full-engine model represented by a set of coupled 3D computational fluid dynamic (CFD) component models. Boundary conditions from the balanced, steady state cycle model are used to define component boundary conditions in the full-engine model. Operating characteristics of the 3D component models are integrated into the cycle model via partial performance maps generated from the CFD flow solutions using one-dimensional mean line turbomachinery programs. This paper highlights the generation of the high-pressure compressor, booster, and fan partial performance maps, as well as turbine maps for the high pressure and low pressure turbine. These are actually "mini-maps" in the sense that they are developed only for a narrow operating range of the component. Results are compared between actual cycle data at a take-off condition and the comparable condition utilizing these mini-maps. The mini-maps are also presented with comparison to actual component data where possible.

Performance optimization of transcritical CO2 refrigeration cycle with thermoelectric subcooler

Abstract: SUMMARY Use of thermoelectric subcooler is one of the techniques to improve the performance of transcritical CO2 cycle Thermodynamic analyses and optimizations of transcritical CO2 refrigeration cycle with thermoelectric subcooler are presented in this paper Further, the effects of various operating parameters on cycle performances are studied It is possible to optimize current supply, discharge pressure, and CO2 subcooling simultaneously based on maximum cooling COP for thermoelectrically enhanced transcritical CO2 refrigeration cycle to get best performance Results show that thermoelectric current supply, COP improvement, and discharge pressure reduction increase with increase in cycle temperature lift, with maximum values of 11 A, 256%, and 154%, respectively, for studied ranges Use of thermoelectric subcooler in CO2 refrigeration system not only improves the cooling COP, also reduces the system high-side pressure, compressor pressure ratio, and compressor discharge temperature, and enhances the volumetric cooling capacity Component-wise irreversibility distribution shows similar trend with basic CO2 cycle, although values are lower leading to higher second law efficiency Cooling capacity may be enhanced by increasing the current supply for the same thermoelectric configuration with penalty of COP Study reveals that thermoelectrically enhanced CO2 refrigeration cycle yields significant performance improvement especially for higher-cycle temperature lift Copyright © 2011 John Wiley & Sons, Ltd

Output Selection and Its Implications for MPC of EGR and VGT in Diesel Engines

Abstract: Control of exhaust gas recirculation (EGR) and variable geometry turbine in diesel engines is a challenging problem and model predictive control (MPC) seems to be a promising method. In MPC the choice of output variables, and thereby the criterion, has a direct impact on the optimization problem to solve and the resulting control performance. Different selections of outputs are investigated and discussed, proposing that it is beneficial to include EGR-fraction and pumping losses in the criterion while having the oxygen/fuel ratio as a constraint. The rational for this constraint is that, in diesel engines, it is allowed to have the oxygen/fuel ratio larger than a set-point. The proposed design also includes integral action of the EGR-fraction to handle model errors and prediction of engine load and speed. A comparison is made between the proposed MPC, a proportional-integral-derivative (PID) controller, and an MPC with intake manifold pressure and compressor flow as outputs, which is the common choice in the literature. Comparisons are performed in simulation on the European transient cycle showing the following two points. First, the proposed design gives 9% lower oxygen/fuel ratio error, 80% lower EGR-error, and 12% lower pumping losses compared to an MPC design with intake manifold pressure and compressor flow as outputs. Second, the proposed design gives 9% lower EGR-error and 6% lower pumping losses compared to a control structure with PID controllers with oxygen/fuel ratio and EGR-fraction as the main outputs.

System and method of recirculating exhaust gas for use in a plurality of flow paths in a gas turbine engine

Abstract: A method includes generating an exhaust gas from combustion gases with a turbine; recirculating the exhaust gas along an exhaust recirculation flow path; reducing moisture within the exhaust gas along the exhaust recirculation path with an exhaust gas processing system; providing the exhaust gas to a first exhaust gas inlet of an exhaust gas compressor for compression; and providing the exhaust gas from the exhaust recirculation path to a second exhaust gas inlet separate from the first exhaust gas inlet for cooling, preheating, sealing, or any combination thereof.

System and method for a stoichiometric exhaust gas recirculation gas turbine system

Abstract: A system includes a turbine combustor, a turbine driven by combustion products from the turbine combustor, and an exhaust gas compressor. The exhaust compressor is configured to compress and route an exhaust gas from the turbine to the turbine combustor. The system also includes an exhaust gas recirculation (EGR) path extending through the exhaust gas compressor, the turbine combustor, and the turbine, a first exhaust gas (EG) extraction port disposed along the EGR path, and a second EG extraction port disposed along the EGR path.

Gas turbine engine shaft bearing configuration

Abstract: A gas turbine engine includes a core housing providing a core flowpath. A shaft supports a compressor section arranged within the core flowpath. First and second bearings support the shaft relative to the core housing and are arranged radially inward of and axially overlapping with the compressor section.

A Three-Dimensional Unsteady CFD Model of Compressor Stability

Abstract: A three-dimensional unsteady CFD code called CSTALL has been developed and used to investigate compressor stability. The code solved the Euler equations through the entire annulus and all blade rows. Blade row turning, losses, and deviation were modeled using body force terms which required input data at stations between blade rows. The input data was calculated using a separate Navier-Stokes turbomachinery analysis code run at one operating point near stall, and was scaled to other operating points using overall characteristic maps. No information about the stalled characteristic was used. CSTALL was run in a 2-D throughflow mode for very fast calculations of operating maps and estimation of stall points. Calculated pressure ratio characteristics for NASA stage 35 agreed well with experimental data, and results with inlet radial distortion showed the expected loss of range. CSTALL was also run in a 3-D mode to investigate inlet circumferential distortion. Calculated operating maps for stage 35 with 120 degree distortion screens showed a loss in range and pressure rise. Unsteady calculations showed rotating stall with two part-span stall cells. The paper describes the body force formulation in detail, examines the computed results, and concludes with observations about the code.

Heat pump system for vehicle and method of controlling the same

Abstract: Disclosed therein are a heat pump system for a vehicle and a method of controlling the heat pump system, which variably controls only a compressor if the number of revolutions of the compressor is less than the upper limit of the number of the maximum revolutions of the compressor and operates an electric heater only when the number of revolutions of the compressor reaches the upper limit of the number of the maximum revolutions of the compressor in order to satisfy a target discharge temperature in a heat pump mode, thereby preventing that convergence of an air discharge temperature of the interior of the vehicle is deteriorated or becomes unstable when the compressor and the electric heater are variably controlled at the same time in order to satisfy the target discharge temperature.

Experimental and Computational Analysis of a Multistage Axial Compressor Including Stall Prediction by Steady and Transient CFD Methods

Abstract: Siemens Energy has commissioned an extensive multi-year experimental and numerical (CFD) project to improve its ability to design for and predict compressor stall. The experimental test rig is a half scale six stage axial compressor. The goal of this work is to provide insight into how best to predict the compressor performance map and in particular the stall point by applying state-of-the-art multiple blade row CFD simulation tools. A preliminary CFD analysis quantified numerical, model and systematic error on the first stage of the compressor. Subsequent steady (Mixing Plane) and transient (Time Transformation) CFD simulations of the entire six stage compressor are compared to each other and to experimental data. Both the steady and transient simulations are shown to be computationally efficient and in very good agreement with the experimental data across the full performance map, up to stall inception on multiple speedlines. Physical explanations of the key flow features observed in the experiment, as well as of the differences between the predictions and experimental data, are given.Copyright © 2013 by Siemens Energy, Inc.