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Showing papers on "Gas compressor published in 2007"


Journal ArticleDOI
TL;DR: In this paper, a component-based modeling methodology for turbocharged engines is described and applied, and new models for the compressor efficiency, compressor flow, and turbine flow are developed.
Abstract: A component based modeling methodology for turbocharged engines is described and applied. Several component models are compiled and reviewed. In addition new models are developed for the compressor efficiency, compressor flow, and turbine flow. Two application examples are finally given where the modeling methodology and the component models have been used. The applications are, firstly, observer design and air/fuel ratio control of SI engines and, secondly, control design of DI engines with VGT and EGR.

217 citations


Patent
20 Mar 2007
TL;DR: In this paper, a control unit is attached to or embedded within a refrigeration appliance to monitor electric power voltage and/or frequency supplied by the mains, and if the unit detects a sag or peak in either the voltage or frequency, the control unit either separates any high demand elements of the appliance from the main power supply, or energizes the elements in a peak.
Abstract: A control unit is attached to or embedded within a refrigeration appliance to monitor electric power voltage and/or frequency supplied by the mains. If the unit detects a sag or peak in either the voltage or frequency, the control unit either separates any high demand elements of the appliance from the mains to reduce demand in a sag or energizes the elements in a peak. When the control system separates the refrigeration compressor from the mains, a food spoilage monitoring system monitors the food storage compartments. This system utilizes food industry temperature and time algorithms to ensure the food does not spoil. If food spoilage could occur, the unit re-energizes the compressor to allow it to lower the temperature provided the power is sufficient to operate the compressor unit without damaging it. Once the sensed temperature is restored to a safe level, the unit separates the compressor from the mains.

197 citations


Patent
20 Dec 2007
TL;DR: In this paper, a power generation system includes a gas turbine system with a combustion chamber, a compressor and an expander, and a purification system to separate the exhaust into a first split stream and a second split stream.
Abstract: A power generation system includes a gas turbine system. The turbine system includes a combustion chamber configured to combust a fuel stream a compressor configured to receive a feed oxidant stream and supply a compressed oxidant to the combustion chamber and an expander configured to receive a discharge from the combustion chamber and generate an exhaust comprising carbon dioxide and electrical energy. The system further includes a retrofittable exhaust gas recirculation system including a splitter configured to split the exhaust into a first split stream and a second split stream, a heat recovery steam generator configured to receive the first split stream and generate a cooled first split stream and a purification system configured to receive the first cooled split stream and the second split stream and generate a recycle stream, wherein the recycle stream is mixed with the fresh oxidant to generate the feed oxidant stream.

145 citations


Patent
06 Feb 2007
TL;DR: In this paper, a reduction in CO2 emission, along with minimal losses of efficiency, is achieved in that carbon dioxide (CO2) is separated from the circulating gas in a CO2 separator, and measures are taken to compensate for the efficiency losses in the gas turbine cyclic process which are associated with the CO2 separation.
Abstract: In a method for generating energy in an energy generating installation (10) having a gas turbine (12), in a first step, an oxygen-containing gas is compressed in a compressor (13, 14) of the gas turbine (12), in a second step the compressed gas is supplied, with the addition of fuel, for combustion in a combustion chamber (15), in a third step the hot flue gas from the combustion chamber (15) is expanded in a turbine (16) of the gas turbine (12) so as to perform work, and, in a fourth step, a branched-off part stream of the expanded flue gas is recirculated into a part of the gas turbine (12) lying upstream of the combustion chamber (15) and is compressed. A reduction in the CO2 emission, along with minimal losses of efficiency, is achieved in that carbon dioxide (CO2) is separated from the circulating gas in a CO2 separator (19), and in that measures are taken to compensate for the efficiency losses in the gas turbine cyclic process which are associated with the CO2 separation.

140 citations


Journal ArticleDOI
TL;DR: In this article, the work potentials of the streams of matter and of heat interactions were analyzed in a methane-fed internal reforming solid oxide fuel cell-gas turbine (IRSOFC-GT) power generation system based on the first and second law of thermodynamics.

130 citations


Journal ArticleDOI
TL;DR: The experimental results confirmed the validity of the proposed design and analysis scheme of the high-speed BLDC motor and the results were validated by finite element method.
Abstract: This paper describes the design and analysis of a high-speed and high-power density BLDC motor for a 50-kW, 70 000-rpm class centrifugal compressor. Design criteria and power loss analysis of the high-speed machine structure are described by analytical method, and the results are validated by finite element method. And then, the prototype machine has been fabricated and tested. The experimental results confirmed the validity of the proposed design and analysis scheme of the high-speed BLDC motor

114 citations


Journal ArticleDOI
TL;DR: In this paper, a two-stage transcritical carbon dioxide heat pump cycles, incorporating options such as flash gas bypass, flash intercooling, and compressor inter cooling, are presented based on cycle simulation.

105 citations


Journal ArticleDOI
TL;DR: In this paper, a multidisciplinary optimization system and its application to the design of a small radial compressor impeller are presented, which uses a genetic algorithm and artificial neural network to find a compromise between the conflicting demands of high efficiency and low centrifugal stresses in the blades.
Abstract: A multidisciplinary optimization system and its application to the design of a small radial compressor impeller are presented. The method uses a genetic algorithm and artificial neural network to find a compromise between the conflicting demands of high efficiency and low centrifugal stresses in the blades. Simultaneous analyses of the aero performance and stress predictions replace the traditional time consuming iterative design approach. The aerodynamic performance, predicted by a 3D Navier-Stokes solver, is maximized while limiting the mechanical stresses to a maximum value. The stesses are calculated by means of a finite element analysis and controlled by modifying the blade camber, lean and thickness at the hub. The results show that it is possible to obtain a significant reduction of the centrifugal stresses in the blades without penalizing the performance.© 2007 ASME

104 citations


Journal ArticleDOI
Baowen Zhang1, Xueyuan Peng1, Z. He1, Z Xing1, Pengcheng Shu1 
TL;DR: In this paper, a double acting free piston expander with a slider-based inlet/outlet control scheme is used to realize a full expansion process for the expander.

101 citations


Patent
13 Dec 2007
TL;DR: In this paper, a turbofan engine assembly is described, which includes a core gas turbine engine (13), a high-pressure compressor (14), a combustor (16), disposed downstream from the high pressure compressor, and a drive shaft (31) coupled between the low-pressure turbine (20) and the fan assembly.
Abstract: A turbofan engine assembly (10) is provided. A turbofan engine assembly includes a core gas turbine engine (13) including a high-pressure compressor (14), a combustor (16) disposed downstream from the high-pressure compressor, and a high-pressure turbine (18) coupled to the high-pressure compressor using a shaft. A turbofan engine assembly (10) further includes counter-rotating booster compressor (22) coupled to the core gas turbine engine, and the counter-rotating booster compressor includes a first rotor section configured to rotate in a first direction and a second rotor section configured to rotate in an opposite second direction. The turbofan engine assembly (10) further includes a single stage fan assembly (12) coupled to the first rotor section, and a drive shaft (31) coupled between the low-pressure turbine (20) and the fan assembly. A turbofan engine assembly (10) further includes a gearbox (100) coupled between the drive shaft and the second rotor section such that the low-pressure turbine drives the gearbox and such that the gearbox drives the second rotor section.

100 citations


Journal ArticleDOI
01 Aug 2007-Energy
TL;DR: In this article, a direct expansion solar-assisted heat pump water heater (DX-SAHPWH) with rated input power 750 W was tested and analyzed, and some suggestions for the system optimization are proposed.

Patent
19 May 2007
TL;DR: In this article, a wind turbine system for producing compressed air from wind energy is described, where a compressor receives mechanical energy from the wind turbine to compress air to an elevated pressure, and the air is stored in a storage devices such that the air may be released from the storage device on demand.
Abstract: A wind turbine system for producing compressed air from wind energy. The wind turbine harvests energy from wind to produce mechanical energy. A compressor receives mechanical energy from the wind turbine to compress air to an elevated pressure. Thermal energy may be removed from the air, and the air is stored in a storage devices, such that the air may be released from the storage device on demand.

Journal ArticleDOI
TL;DR: A modification to the "fast" reference governor (FRG) design is proposed to make it applicable to the nonlinear fuel cell plant and it is shown that the computations of the load governor can be performed in real-time.
Abstract: A compressor-based air supply system in a fuel cell is susceptible to saturation during fast transients in load. Aggressive control of the air compressor may result in compressor surge or choke, disrupt the flow of air into the cathode of a fuel cell stack, and negatively impact the fuel cell power generation. Low partial oxygen pressure in the cathode caused by rapid increase in load may also damage the stack and reduce its life. A load governor can be added to the air supply control system to monitor the load and prevent violation of constraints (compressor surge, choke, and partial oxygen pressure) by modifying the load command to the fuel cell system. In this paper, we present the steps involved in the design of such a load governor for the fuel cell application. To reduce the online computations, we utilize the "fast" reference governor (FRG) approach which has been developed for linear systems. FRG utilize a "maximal constraint admissible set" calculated offline and, thus, require fewer online calculations. We propose a modification to the FRG design to make it applicable to the nonlinear fuel cell plant. The scheme is then implemented on a real-time simulation platform and it is shown that the computations of the load governor can be performed in real-time

Patent
28 Sep 2007
TL;DR: In this paper, a turbine system consisting of a compressor configured to compress ambient air and a combustor configured to receive compressed air from the compressor, and to combust a fuel stream to generate an exhaust gas.
Abstract: A turbine system is provided. The turbine system includes a compressor configured to compress ambient air and a combustor configured to receive compressed air from the compressor, and to combust a fuel stream to generate an exhaust gas. The turbine system also includes a turbine for receiving the exhaust gas from the combustor to generate electricity; wherein a first portion of the exhaust gas is mixed with the ambient air to form a low-oxygen air stream, and wherein the low-oxygen air stream is compressed using the compressor, and is directed to the combustor for combusting the fuel stream to generate a low-NOx exhaust gas.

Journal ArticleDOI
TL;DR: It is found that super-heating should be minimized whereas some sub-cooling is optimal, for a simple ammonia cycle, which gives savings in compressor power of about 2%.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the impact of bleed air on the performance and operability of highly loaded turbocharger designs and found that the path into compression system instability is altered by the bleed flow.
Abstract: In turbocharger applications bleed air near the impeller exit is often used for secondary flow systems to seal bearing compartments and to balance the thrust load on the bearings. There is experimental evidence that the performance and operability of highly loaded centrifugal compressor designs can be sensitive to the amount of bleed air. To investigate the underlying mechanisms and to assess the impact of bleed air on the compressor dynamic behavior, a research program was carried out on a pre-production, 5.0 pressure ratio, high-speed centrifugal compressor stage of advanced design. The investigations showed that bleed air can significantly reduce the stable flow range. Compressor rig experiments, using an array of unsteady pressure sensors and a bleed valve to simulate a typical turbocharger environment, suggest that the path into compression system instability is altered by the bleed flow. Without bleed flow, the pre-stall behavior is dominated by short wavelength disturbances, or so called ‘spikes’, in the vaneless space between the impeller and the vaned diffuser. Introducing bleed flow at impeller exit reduces endwall blockage in the vaneless space and destabilizes the highly-loaded vaned diffuser. The impact is a 50% reduction in stable operating range. The altered diffuser characteristic reduces the compression system damping responsible for long wavelength, modal pre-stall behavior. A four-lobed backward traveling rotating stall wave is experimentally measured, in agreement with calculations obtained from a previously developed dynamic compressor model. In addition, a self-contained, endwall blockage control strategy was employed, successfully recovering 75% of the loss in surge-margin due to bleed flow and yielding a 1 point increase in adiabiatic compressor efficiency.Copyright © 2007 by ASME

Journal ArticleDOI
TL;DR: In this paper, a closed-loop-steam-cooling was used to improve the performance of a reheat gas-steam combined cycle, and the results showed that the closedloop steam cooling was superior to air-film cooling.

Patent
Joseph Kirzhner1
04 Sep 2007
TL;DR: In this paper, a method and system for operating at partial load a gas turbine system having a compressor, a combustor, and a turbine is presented, which may include the steps of lowering a flow of fuel to the combustionor, extracting air from the compressor so as to lower a flow to the compressor, and returning the extracted air to the turbine or a component of the gas turbine systems other than the combustor.
Abstract: A method and system for operating at partial load a gas turbine system having a compressor, a combustor, and a turbine. The method and system may include the steps of lowering a flow of fuel to the combustor, extracting air from the compressor so as to lower a flow of air to the compressor, and returning the extracted air to the turbine or a component of the gas turbine system other than the combustor. Extracting air from the compressor raises a combustion temperature within the combustor. Raising the combustion temperature maintains a combustion exhaust below a predetermined level, maintains stable combustion, and extends turbine turndown values.

Journal ArticleDOI
TL;DR: In this paper, three two-phase ejectors are used as an expansion device in the refrigeration cycle, and the effects of throat diameter of the motive nozzle, on the coefficient of performance, primary mass flow rate of the refrigerant, secondary mass flow ratio of the fluid, recirculation ratio, average evaporator pressure, compressor pressure ratio, discharge temperature and cooling capacity are presented.
Abstract: This paper is a part in a series that reports on the experimental study of the performance of the two-phase ejector expansion refrigeration cycle. In the present study, three two-phase ejectors are used as an expansion device in the refrigeration cycle. The effects of throat diameter of the motive nozzle, on the coefficient of performance, primary mass flow rate of the refrigerant, secondary mass flow rate of the refrigerant, recirculation ratio, average evaporator pressure, compressor pressure ratio, discharge temperature and cooling capacity, which have never before appeared in open literature, are presented. The effects of the heat sink and heat source temperatures on the system performance are also discussed.

Journal ArticleDOI
TL;DR: In this article, an interesting solution based on a specifically designed inlet swirl-generator device (SGD) was proposed to palliate negative effects of the inlet inlet duct of the centrifugal compressor.

Patent
31 Jan 2007
TL;DR: In this article, an inlet bleed heat and power augmentation system utilizing a bi-directional and common piping arrangement is described, which includes a plurality of feed tubes arranged to communicate either steam to a compressor discharge plenum or compressed air from the compressor discharging plenum.
Abstract: An inlet bleed heat and power augmentation system utilizing a bi-directional and common piping arrangement is disclosed. The piping arrangement includes a plurality of feed tubes arranged to communicate either steam to a compressor discharge plenum or compressed air from the compressor discharge plenum. Various embodiments of the invention are discussed including operation methods.

Patent
18 Apr 2007
TL;DR: In this paper, an outlet valve through an outlet duct in a wall of a housing is used to return exhaust fluid flow from the heat exchanger to the bypass flow with reduced drag effects whilst recovering thrust.
Abstract: In certain circumstances recovery of a fluid flow presented through a heat exchanger into another flow can create problems with respect to drag and loss of thrust In gas turbine engines heat exchangers are utilized for providing cooling of other flows such as in relation to compressor air taken from the core of the engine and utilized for cabin ventilation and de-icing functions By providing an outlet valve through an outlet duct in a wall of a housing the exhaust fluid flow from the heat exchanger can be returned to the by-pass flow with reduced drag effects whilst recovering thrust The valve may take the form of a flap displaceable into the by-pass flow before an exit plan to create a reduction in static pressure drawing fluid flow through the heat exchanger

Journal ArticleDOI
TL;DR: In this article, the design characteristics and performance of a pressurized solid oxide fuel cell (SOFC) hybrid system using a fixed gas turbine (GT) design are analyzed, where the gas turbine is assumed to exist prior to the hybrid system design and all the other components such as the SOFC module and auxiliary parts are assumed to be newly designed for the hybrid systems.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the energy saving potential of using variable-speed capacity control instead of the conventional intermittent operation mode for domestic ground source heat pumps for hydronic heating systems.
Abstract: The objective of this study was to investigate the energy-saving potential of using variable-speed capacity control instead of the conventional intermittent operation mode for domestic ground source heat pumps. Variable-speed capacity control is commonly used in air-to-air heat pumps, but not in ground source heat pumps for hydronic heating systems, even though the energy-saving potential may be greater for this application. A theoretical analysis indicates how the energy efficiency is influenced by variable-speed capacity control of the compressor. The analysis shows that, to take full advantage of the capacity control, care should be taken to achieve the correct relationship between refrigerant flow and heat transfer media flows. Intermittent control and variable-speed capacity control were compared by laboratory tests on two capacity-controlled heat pumps and one standard heat pump with a single-speed compressor. Test data were then used for seasonal performance factor (SPF) calculations. The SPF calculations show that despite improved performance at part load the variable-speed controlled heat pump did not improve the annual efficiency compared to the intermittently operated heat pump. This is mainly due to inverter and compressor motor efficiencies and the need for improved efficiency and control of pumps used in the heating and ground collector systems.

Patent
05 Nov 2007
TL;DR: A gas turbine engine includes a compressor, combustor, and high pressure turbine operatively joined together as mentioned in this paper, and an interstage cooling circuit is joined in flow communication from an intermediate stage of the compressor to a forward face of an HP disk supporting a row of turbine blades for channeling interstage bleed cooling air.
Abstract: A gas turbine engine includes a compressor, combustor, and high pressure (HP) turbine operatively joined together. An interstage cooling circuit is joined in flow communication from an intermediate stage of the compressor to a forward face of an HP disk supporting a row of turbine blades for channeling interstage bleed cooling air thereto.

Patent
28 Jun 2007
TL;DR: In this article, a representative gas turbine includes a spool, a compressor, and a turbine mechanically coupled to the spool; the compressor having a first set of blades and a second set of engines, the second engine being located downstream of the first engine, and the first and second engines being driven by the same spool.
Abstract: Gas turbines with multiple gas flow paths are provided. In this regard, a representative gas turbine includes: a spool; a compressor; a turbine mechanically coupled to the spool; the compressor having a first set of blades and a second set of blades, the second set of blades being located downstream of the first set of blades, the first set of blades and the second set of blades being driven by the spool; and means for enabling the first set of blades to rotate at a lower rotational speed than the second set of blades.

Patent
02 Oct 2007
TL;DR: A refrigeration system can include a liquid-refrigerant injection system that can inject liquid refrigerant into an intermediate-pressure location of the compressor, which can absorb the heat of compression during the compression process as discussed by the authors.
Abstract: A refrigeration system can use a flash tank to separate vapor refrigerant from liquid refrigerant. The refrigeration system can include a liquid-refrigerant injection system that can inject liquid refrigerant into an intermediate-pressure location of the compressor. The injected liquid refrigerant can absorb the heat of compression during the compression process. The refrigeration system can include an economizer system that injects a refrigerant vapor into an intermediate-pressure location of the compressor in conjunction with the injection of the cooling liquid. The refrigeration system can incorporate a cooling-liquid injection system that can inject a cooling liquid into an intermediate-pressure location of the compressor.

Proceedings ArticleDOI
01 Jan 2007
TL;DR: In this paper, steady and unsteady RANS simulations were performed to investigate vortical flow structures and separated flow field near the tip for several different clearance cases, and boundary layer separation on the casing wall and blade suction surface was investigated in detail for near-stall and stall condition.
Abstract: It is known that the tip clearance flow is dominant and very important flow phenomena in axial compressor aerodynamics because the tip clearance flow has a great influence on the stability as well as aerodynamic loss of compressors. Our goal is to clarify the behavior of tip clearance flow at near-stall condition in a transonic axial compressor rotor (NASA Rotor 37). In the present work, steady and unsteady RANS simulations were performed to investigate vortical flow structures and separated flow field near the tip for several different clearance cases. Boundary layer separation on the casing wall and blade suction surface was investigated in detail for near-stall and stall condition. In order to understand such complicated flow field, vortex cores were identified using the critical point theory and a topology of the three-dimensional separated and vortical flows was analyzed. In the nominal clearance case, the breakdown of tip leakage vortex has occurred at a near-stall operating condition because of the interaction of the vortex with the shock wave, leading to a large blockage and unsteadiness in the rotor tip. On the other hand, the calculation with no clearance suggested that the separation on the suction surface was different from that with the nominal clearance. Since the shock wave induced the boundary layer separation on the blade suction surface in the transonic axial compressor rotor, focal-type critical points appeared on the suction surface near the tip at near-stall condition.Copyright © 2007 by ASME

Journal ArticleDOI
TL;DR: In this paper, a fluid-dynamic model of the mixture in the Knudsen compressor is derived, and it is numerically demonstrated that the compressor works certainly as a gas separator.
Abstract: A possibility of making use of the Knudsen compressor as a gas separator is investigated. Starting from the description at the microscopic level on the basis of the kinetic theory of gases, a fluid-dynamic model describing the behaviour of the mixture in the Knudsen compressor is derived. Then, by the use of this model, it is numerically demonstrated that the Knudsen compressor works certainly as a gas separator. The separation performance is shown to reach a practical level by increasing the number of elemental units in the device. The numerical simulation is carried out for various molecular models, not only for fundamental models, the hard-sphere and Maxwell molecules, but also for more realistic models such as the inverse power-law potential and Lennard-Jones models, assuming the McCormack model equation at the microscopic level. The results show that the modelling by the celebrated Maxwell molecule (or the BGK-type model equation) fails to capture the phenomenon of the gas separation in the device. This presents a remarkable contrast to the capability of the other fundamental model, the hard-sphere molecule, even though this model exaggerates the phenomenon to some extent.

Journal ArticleDOI
TL;DR: In this paper, a dynamic mathematical model for coupling the refrigeration system and PCMs has been developed, which consists of the following basic components: a compressor, a condenser, an expansion valve, an evaporator cooler and a PCM heat exchanger.