Showing papers on "Gas compressor published in 2004"

Ultra low-voltage low-power CMOS 4-2 and 5-2 compressors for fast arithmetic circuits

Abstract: This paper presents several architectures and designs of low-power 4-2 and 5-2 compressors capable of operating at ultra low supply voltages. These compressor architectures are anatomized into their constituent modules and different static logic styles based on the same deep submicrometer CMOS process model are used to realize them. Different configurations of each architecture, which include a number of novel 4-2 and 5-2 compressor designs, are prototyped and simulated to evaluate their performance in speed, power dissipation and power-delay product. The newly developed circuits are based on various configurations of the novel 5-2 compressor architecture with the new carry generator circuit, or existing architectures configured with the proposed circuit for the exclusive OR (XOR) and exclusive NOR ( XNOR) [XOR-XNOR] module. The proposed new circuit for the XOR-XNOR module eliminates the weak logic on the internal nodes of pass transistors with a pair of feedback PMOS-NMOS transistors. Driving capability has been considered in the design as well as in the simulation setup so that these 4-2 and 5-2 compressor cells can operate reliably in any tree structured parallel multiplier at very low supply voltages. Two new simulation environments are created to ensure that the performances reflect the realistic circuit operation in the system to which these cells are integrated. Simulation results show that the 4-2 compressor with the proposed XOR-XNOR module and the new fast 5-2 compressor architecture are able to function at supply voltage as low as 0.6 V, and outperform many other architectures including the classical CMOS logic compressors and variants of compressors constructed with various combinations of recently reported superior low-power logic cells.

Millimeter-Scale, Micro-Electro-Mechanical Systems Gas Turbine Engines

Abstract: The confluence of market demand for greatly improved compact power sources for portable electronics with the rapidly expanding capability of micromachining technology has made feasible the development of gas turbines in the millimeter-size range. With airfoil spans measured in 100's of microns rather than meters, these microengines have about 1 millionth the airflow of large gas turbines and thus should produce about one millionth the power, 10-100 W. Based on semiconductor industry-derived processing of materials such as silicon and silicon carbide to submicron accuracy, such devices are known as micro-electro-mechanical systems (MEMS). Current millimeter-scale designs use centrifugal turbomachinery with pressure ratios in the range of 2:1 to 4:1 and turbine inlet temperatures of 1200-1600 K. The projected performance of these engines are on a par with gas turbines of the 1940s. The thermodynamics of MEMS gas turbines are the same as those for large engines but the mechanics differ due to scaling considerations and manufacturing constraints. The principal challenge is to arrive at a design which meets the thermodynamic and component functional requirements while staying within the realm of realizable micromachining technology. This paper reviews the state of the art of millimeter-size gas turbine engines, including system design and integration, manufacturing, materials, component design, accessories, applications, and economics. It discusses the underlying technical issues, reviews current design approaches, and discusses future development and applications.

Thermal power plant with sequential combustion and reduced-co2 emission, and a method for operating a plant of this type

Abstract: The invention relates to a thermal power plant with sequential combustion and reduced CO2 emissions, said plant having the following components that are connected in series by at least one flow channel (S): a combustion intake air compressor unit (1), a first combustion chamber (2), a high-pressure turbine stage (3), a second combustion chamber (4), in addition to a low-pressure turbine stage (5) The second combustion chamber (4) and/or the low-pressure turbine stage (5) can be supplied with a cooling gas stream for cooling purposes The invention also relates to a method for operating a thermal power plant of this type The invention is characterised in that the plant is equipped with a recirculation conduit (6), which feeds at least part of the exhaust gas stream that emerges from the low-pressure turbine stage (5) to a compressor unit (7), a cooling conduit (8), which feeds at least part of the compressed exhaust gas stream that emerges from the compressor unit (7) to the second combustion chamber (4) and/or the low-pressure turbine stage (5) for cooling purposes and a CO2 separation unit (9) that is located in the cooling conduit (8) and that separates at least portions of CO2 from the cooling gas stream

Variable capacity rotary compressor

Abstract: A variable capacity rotary compressor includes a hermetic casing, a housing installed in the hermetic casing to define therein first and second compression chambers having different capacities, and a compressing unit placed in the first and second compression chambers and operated to execute a compression operation in either the first or second compression chamber according to a rotating direction of a rotating shaft which drives the compressing unit. The compressor further includes a suction path controller, a high-pressure pipe, and a high-pressure path controller. The suction path controller controls a refrigerant suction path so that a refrigerant is delivered into an inlet port of the first or second compression chamber where the compression operation is executed. The high-pressure pipe couples an outlet side of the compressor to the suction path controller. The high-pressure path controller is provided at a predetermined portion of the suction path controller, and controls a high-pressure path so that the high-pressure pipe communicates with the inlet port of the first or second compression chamber where an idle operation is executed, according to variance of temperature when the refrigerant suction path is controlled by the suction path controller.

Performance representation of variable-speed compressor for inverter air conditioners based on experimental data

Abstract: Variable speed control of compressors is one of the best methods to regulate the capacity of heat pumps and air conditioners. An analysis is conducted for modeling the variable speed compressor for simulation of inverter air conditioner and heat pump. Having scattered the real operation performance of inverter compressor into infinite operation performance of constant speed compressor, the map-based method is utilized to fit the performance curves of inverter compressor. The model is built at the basic frequency and the map condition as the second-order function of condensation temperature and evaporation temperature. Then it is corrected by the compressor frequency as the second-order function of frequency and by the actual operating condition as the actual specific volume of the suction gas. This method is used to set up simulation models of three different compressors. Compared with the data provided by the compressor manufacturers, the average relative errors are less than 2, 3 and 4% for refrigerant mass flow rate, compressor power input and coefficient of performance (COP), respectively. This model of variable speed compressor is suitable for the simulation of inverter air conditioner and heat pump systems. Based on the experimental data and simulation model, the frequency at zero mass flow rate and power input at zero frequency are discussed and the relation between COP and compressor frequency is analyzed.

Method of generating energy in a power plant comprising a gas turbine, and power plant for carrying out the method

Abstract: A method of generating energy in a power plant ( 30 ) having a gas turbine ( 29 ), includes a first step a gas containing air ( 1 ) is compressed in a first compressor ( 2 ) of the gas turbine ( 29 ), a second step the compressed gas ( 3, 3 a, 3 b; 5; 7 a, 7 b ) is fed to a combustion process with the addition of fuel ( 8 ) in a combustor ( 23 ), a third step the hot flue gas ( 9 ) from the combustor ( 23 ) is expanded in an expander or a turbine ( 10 ), driving a generator ( 18 ), of the gas turbine ( 29 ) while performing work, and a fourth step a partial flow of the expanded flue gas ( 11 ) is recirculated to the inlet of the first compressor ( 2 ) and admixed with the gas containing air ( 1 ). Carbon dioxide (CO 2 ) is separated from the compressed gas ( 3, 3 a, 3 b; 5; 7 a, 7 b ) in a CO 2 separator ( 6 ) before the third step. In such a method, the overall size and energy costs are reduced by virtue of the fact that, to permit increased CO 2 concentrations in the CO 2 separator ( 6 ), not more than about 70 % of the carbon dioxide contained in the compressed gas ( 3, 3 a, 3 b; 5, 5 a, 5 b; 7 a, 7 b ) is removed from the compressed gas ( 3, 3 a, 3 b; 5, 5 a, 5 b; 7 a, 7 b ).

Refrigeration cycle device

Abstract: PROBLEM TO BE SOLVED: To provide a refrigeration cycle device capable of preventing oil from becoming biased when a first compressor and a second compressor are connected in series in a refrigerant circuit SOLUTION: This refrigeration cycle device is provided with the first compressor 37, the second compressor 54 connected with the first compressor in series in the refrigerant circuit, and oil separators 31, 45 provided on refrigerant discharge sides of each compressor 37, 54, respectively Each oil separator 31, 45 is provided with a flow-out hole 72 for letting oil flow out into the refrigerant circuit when oil level reaches specified amount COPYRIGHT: (C)2004,JPO&NCIPI

Fuzzy control of the compressor speed in a refrigeration plant

Abstract: In this paper, referring to a vapor compression refrigeration plant subjected to a commercially available cold store, a control algorithm, based on the fuzzy logic and able to select the most suitable compressor speed in function of the cold store air temperature, is presented. The main aim is to evaluate the energy saving obtainable when the fuzzy algorithm, which continuously regulates the compressor speed by an inverter, is employed to control the compressor refrigeration capacity instead of the classical thermostatic control, which imposes on/off cycles on the compressor that works at the nominal frequency of 50 Hz. The variation of the reciprocating compressor speed is obtained by controlling the compressor electric motor supply current frequency in the range 30–50 Hz, as it is not possible to consider values smaller than 30 Hz because of the lubrication troubles due to the splash system. In this range, two among the most suitable working fluids proposed for the R22 substitution, such as the R407C (R32/R125/R134a 23/25/52% in mass) and the R507 (R125/R143A 50/50% in mass) are tested. Comparing the compressor speed fuzzy control with the classical thermostatic control, frequently used in the cold stores and in other refrigeration systems, the experimental results show a meaningful energy saving equal even to about 13% when the R407C is used as a working fluid. In particular, to explain from the energy saving point of view the best performances of the refrigeration plant when the compressor speed varies, an exergetic analysis is realized. Besides, with regard to the inverter cost, the pay-back period determined is more than acceptable for the plant size examined.

Air conditioning system for vehicles

Abstract: An air conditioning system for a vehicle includes a hybrid compressor having a first compression mechanism driven by a drive source for driving the vehicle and a second compression mechanism driven by an electric motor, means for selecting a drive source, a means for detecting a refrigeration cycle condition, and means for estimating a power consumption of the compressor due to a selected drive source and a power consumption of the compressor due to a non-selected drive source in response to a value detected by the means for detecting a refrigeration cycle condition, when one drive source has been selected. Through this estimation, an preferred drive source may be selected in response to the condition of the refrigeration cycle or a thermal load.

High-pressure-turbine clearance control systems: Current practices and future directions

Abstract: Improved blade-tip sealing in a high-pressure compressor and high-pressure turbine can provide dramatic improvements in specific fuel consumption, time on wing, compressor stall margin, and engine efficiency as well as increased payload and mission range capabilities. Maintenance costs to overhaul large commercial gas turbine engines can easily exceed $1 million. Removal of engines from service is primarily due to the spent exhaust gas temperature margin caused mainly by the deterioration of high-pressure-turbine components. Increased blade-tip clearance is a major factor in hot-section component degradation. As engine designs continue to push the performance envelope with fewer parts and the market drives manufacturers to increase service life, the need for advanced sealing continues to grow. A review of aero-gas-turbine engine high-pressure-turbine performance degradation and the mechanisms that promote these losses are presented. Benefits to the high-pressure turbine due to improved clearance management are identified. Past and present sealing technologies are presented along with specifications for next-generation engine clearance control systems.

Gas turbine installation

Abstract: A gas turbine installation which includes a compressor which compresses supplied air and discharges the same, a combustor which combusts the compressed air obtained from the compressor and fuel and produces combustion gas, a turbine which is driven by combustion gas provided from the combustor, a regenerative heat exchanger which heats all or a part of the compressed air being supplied from the compressor to the combustor by making use of the heat of the exhaust gas exhausted from the turbine and a plurality of water spraying devices which are provided at positions from an intake air chamber of the compressor to the outlet of low temperature side gas flow passage in the regenerative heat exchanger and is characterized in that the regenerative heat exchanger is constituted by connecting in series a plurality of heat exchangers having different heat transfer surface configurations. Thereby, a gas turbine installation is provided which suppresses generation of erosion and scales due to water droplets and shows a high efficiency and a high output.

Inlet Fogging of Gas Turbine Engines—Part I: Fog Droplet Thermodynamics, Heat Transfer, and Practical Considerations

Abstract: The inlet fogging of gas turbine engines for power augmentation has seen increasing application over the past decade yet not a single technical paper treating the physics and engineering of the fogging process, droplet size measurement, droplet kinetics, or the duct behavior of droplets, from a gas turbine perspective, is available. This paper provides the results of extensive experimental and theoretical studies conducted over several years coupled with practical aspects learned in the implementation of nearly 500 inlet fogging systems on gas turbines ranging in power from 5 to 250 MW. Part A of the paper covers the underlying theory of droplet thermodynamics and heat transfer, and provides several practical pointers relating to the implementation and application of inlet fogging to gas turbine engines.

Adiabatic Effectiveness Measurements of Endwall Film-Cooling for a First-Stage Vane

Abstract: In gas turbine development, the direction has been towards higher turbine inlet temperatures to increase the work output and thermal efficiency. This extreme environment can significantly impact component life. One means of preventing component burnout in the turbine is to effectively use film-cooling whereby coolant is extracted from the compressor and injected through component surfaces. One such surface is the endwall of the first stage nozzle guide vane. This paper presents measurements of two endwall film-cooling hole patterns combined with cooling from a flush slot that simulates leakage flow between the combustor and turbine sections. Adiabatic effectiveness measurements showed the slot flow adequately cooled portions of the endwall. Measurements also showed two very difficult regions to cool including the leading edge and pressure side-endwall junction. As the momentum flux ratios were increased for the film-cooling jets in the stagnation region, the coolant was shown to impact the vane and wash down onto the endwall surface. Along the pressure side of the vane in the upstream portion of the passage, the jets were shown to separate from the surface rather than penetrate to the pressure surface. In the downstream portion of the passage, the jets along the pressure side of the vane were shown to impact the vane thereby eliminating any uncooled regions at the junction. The measurements were also combined with computations to show the importance of considering the trajectory of the flow in the near-wall region, which can be highly influenced by slot leakage flows.Copyright © 2004 by ASME

Efficient combined cycle power plant with CO2 capture and a combustor arrangement with separate flows

Abstract: The invention relates to a method for inter alia to increase the energy and cost efficiency of a gas power plant or a thermal heat plant with C02 capturing. The power plant comprises gas turbine plants (12,12') comprising compressor units (13,13') and turbine units (14,14') and further comprises a combustor (10). The combustor (10) is working in principle with to separate gas part streams where one gas part stream flows internally through the flame tube (40) of the combustor (10), while the other gas part stream is flowing along the exterior of the flame tube (40). The first gas part stream comprises additional air and re-circulated, un­cleaned flue gas from the combustor (10), said gases being combusted together with fuel inside the flame tube (40). The second gas part stream comprises cleaned flue gas which is heated up at the exterior of the flame tube (40) while the flame tube (40) is cooled down. The invention comprises also a power plant, a combustor and a C02 capture plant.

Methods and apparatus for starting up emission-free gas-turbine power stations

Abstract: In a power generation plant having at least one gas turbine cycle with heat-recovery boiler (4) and at least one steam turbine cycle operated via the heat-recovery boiler (4), the gas turbine cycle being designed to be semi-closed and essentially free of emissions and essentially comprising a compressor (1), a combustion chamber (2) arranged downstream of the compressor (1), a gas turbine (3) arranged downstream of the combustion chamber (2), a heat-recovery boiler (4) arranged downstream of the gas turbine (3), and at least one generator (8) coupled to the gas turbine (3), modes of operation with the gas turbine cycle stopped and start-up using fresh air are made possible by first means (12) being arranged which alternatively or additionally allow hot gas to be fed into the hot-gas path (23) between gas turbine (3) and heat-recovery boiler (4), and by second means (15) being arranged which alternatively or additionally allow exhaust gas to be expelled from the exhaust-gas path (40) downstream of the heat-recovery boiler (4).

Compressor Stall Control Through Endwall Recirculation

Abstract: Experiments that demonstrate the use of endwall recirculation to control the stall of transonic compressor stages are described. Endwall recirculation of a compressor stage is implemented by bleeding air from the casing downstream of a stator blade row and injecting the air as a wall jet upstream of a preceding rotor blade row. The bleed ports, injection ports, and recirculation channels are circumferentially discrete, and occupy only 20–30% of the circumference. The development of compact wall-jet injectors is described first. Next, the results of proof-of-concept steady recirculation tests on a single-stage transonic compressor are presented. Finally, the potential for using endwall recirculation to increase the stability of transonic highly-loaded multistage compressors is demonstrated through results from a rig test of simulated recirculation driving both a steady injected flow and an unsteady injected flow commanded by closed-loop active control during compressor operation at 78–100% of design speed. In this test air from an external source was injected upstream of several rotor blade rows while compressor bleed was increased by an amount equivalent to the injected massflow. During closed loop control, wall static pressure fluctuations were monitored and the injected flow rate was controlled to reduce the stalling mass flow. The use of wall jet injection to study the dynamics of transonic compressor stages is also discussed.Copyright © 2004 by ASME

Method and system for recovering carbon dioxide

Abstract: To provide a method for recovering carbon dioxide, in which thermal energy for regenerating a CO2 absorbing solution and power for compressing the recovered CO2 are supplied, and high thermal efficiency is achieved, and a system therefor. A system for recovering carbon dioxide including a high pressure turbine 3, an intermediate pressure turbine 7, and a low pressure turbine 8; a boiler 1 for generating steam for driving the turbines; an absorption tower 18 filled with a CO2 absorbing solution for absorbing and removing CO2 from combustion exhaust gas of the boiler; a regeneration tower 24 for regenerating the absorbing solution having absorbed CO2; a compressor 42 for compressing the removed CO2; a turbine 41 for a compressor, which is driven by some of the exhaust steam of the high pressure turbine; turbines 51 and 52 for auxiliary machinery, which are driven by some of the exhaust steam of the intermediate pressure turbine; and supply pipes 45 and 55 for supplying exhaust steam of the compressor turbine and the auxiliary machinery turbines to a reboiler 30 of the regeneration tower as a heating source.

Compressor protection and diagnostic system

Abstract: A compressor assembly includes a shell, a compressor housed within the shell, and a motor drivingly connected to the compressor. In addition, a sensor assembly is provided for monitoring operating parameters of the compressor assembly. Processing circuitry, in communication with the sensor assembly, is operable to process the operating parameters of the compressor assembly according to predefined rules. Furthermore, a terminal assembly is hermetically secured to the shell and is in communication with the sensor assembly. A plug is attached to the terminal assembly outside of the shell and serves to operably connect the processing circuitry with the sensor assembly.

System and method for using hot gas reheat for humidity control

Abstract: A humidity control method is provided for a multi-stage cooling system having two or more refrigerant circuits that balances humidity control and cooling demand. Each refrigerant circuit includes a compressor, a condenser and an evaporator. A hot gas reheat circuit having a hot gas reheat coil is connected to one of the refrigerant circuits and is placed in fluid communication with the output airflow from the evaporator of that refrigerant circuit to provide additional dehumidification to the air when humidity control is requested. The hot gas reheat circuit bypasses the condenser of the refrigerant circuit during humidity control. Humidity control is only performed during cooling operations and ventilation operations.

Series/parallel turbochargers and switchable high/low pressure EGR for internal combustion engines

Abstract: Systems and methods for turbocharging an internal combustion engine include operating two turbochargers in a series configuration for a first operating region and a parallel configuration for a second operating region. Systems and methods for controlling exhaust gas recirculation (EGR) in a turbocharged internal combustion engine provide low pressure EGR upstream of a compressor inlet for a first operating region and high pressure EGR downstream of a compressor outlet for a second operating range to further improve turbocharger operating margin and overall efficiency.

Compressor diagnostic and recording system

Abstract: A compressor diagnostic system incorporates a control which receives a plurality of data streams about various operational features of the compressor. As an example, both temperature and pressure of the suction and discharge refrigerant are taken and sent to the control. Moreover, information with regard to the power being supplied to the motor is taken and stored. All of this information is utilized at a control which compares the information to expected values and determines a fault based upon the evaluation. Moreover, in another feature of this invention, much of this data is stored, and maintained at the compressor. In the event of a compressor failure, this stored information will provide a maintenance worker with a good indication of why the compressor failed.

Low volumetric compression ratio integrated turbo-compound rotary engine

Abstract: A compound cycle engine (10) comprises a compressor and a turbine section (14, 18), and at least one cycle topping device (16) providing an energy input to the turbine section (18). The compressor section (14) compresses the air according to a pressure ratio PRgt. The cycle topping device (16) further compresses the air according to a volumetric compression ratio Rvc, and wherein PRgt x Rvc are selected, according to one aspect of the invention, to provide a cycle which permit a more compact and lighter compound cycle engine to be provided.

Gas turbine having exhaust recirculation

Abstract: A gas turbine adapted to operate in a highly diluted mode comprises a compressor 3 adapted to compress oxidant 5; a combustion chamber 3 adapted to accept the compressed oxidant 7 and provide an exit means for flue gas 9; a turbine 4; and a flue gas re-circulation means 12, 13 adapted to re-circulate the flue gas 9 from the combustion chamber 3 and mix the said flue gas with the compressed oxidant 7 from the compressor 2 in order to provide a highly diluted mode of combustion with a flue gas re-circulation rate of from 100% to 200%.

Vaporization of liquefied natural gas for increased efficiency in power cycles

Abstract: A gas turbine cycle that utilizes the vaporization of liquefied natural gas as a source of inlet air chilling for a gas turbine. The cycle uses regeneration for preheating of combustor air and offers the potential of gas turbine cycle efficiencies in excess of 60%. The systems and methods permit the vaporization of LNG using ambient air, with the resulting super cooled air being easier to compress and/or having fewer contaminants therein. As the air is easier to compress, less energy is needed to operate the compressor, thereby increasing the efficiency of the system. A portion of the vaporized natural gas may be used as the combustion fuel for the gas turbine system, thereby permitting multiple turbines to be operated using a single topping cycle. In alternative embodiments, the vaporization of the LNG may be used as part of a bottoming cycle to increase the efficiencies of the gas turbine system.

Parametric Study of Tip Clearance—Casing Treatment on Performance and Stability of a Transonic Axial Compressor

Abstract: The control of tip leakage flow (TLF) through the clearance gap between the moving and stationary components of rotating machines is still a high-leverage area for improvement of stability and performance of aircraft engines. Losses in the form of flow separation, stall, and reduced rotor work efficiency are results of the tip leakage vortex (TLV) generated by interaction of the main flow and the tip leakage jet induced by the blade pressure difference. The effects are more detrimental in transonic compressors due to the interaction of shock-TLV. It has been previously shown that the use of slots and grooves in the casing over tip of the compressor blades, known as casing treatment, can substantially increase the stable flow range and therefore the safety of the system but generally with some efficiency penalties. This paper presents a numerical parametric study of tip clearance coupled with casing treatment for a transonic axial-flow compressor NASA Rotor 37. Compressor characteristics have been compared to the experimental results for smooth casing with a 0.356 mm tip clearance and show fairly good agreement. Casing treatments were found to be an effective means of reducing the negative effects of tip gap flow and vortex, resulting in improved performance and stability. The present work provides guidelines for improvement of steady-state performance of the transonic axial-flow compressors and improvement of the stable operating range of the system.Copyright © 2004 by ASME

Heat pump system

Abstract: A heat pump system ( 10 ) including a heat generator ( 15 ), a heat engine ( 26 ) supplied with heat engine working fluid ( 18 ) by the heat generator ( 15 ) having a heat engine cylinder chamber ( 34 ), a heat engine piston ( 32 ), and a heat engine piston rod ( 35 ), a preheating chamber ( 31 ) employing the heat engine working fluid ( 18 ) to heat the heat engine cylinder chamber ( 34 ), a compressor ( 40 ) driven by the heat engine ( 26 ) employing compressor working fluid having a compressor cylinder chamber ( 46 ), a compressor piston ( 44 ), and a compressor piston rod ( 47 ), a spacer ( 50 ) separating and joining the heat engine piston rod ( 35 ) and the compressor piston rod ( 47 ), a sealing assembly ( 38 ) associated with the spacer ( 50 ) separating the heat engine working fluid ( 18 ) and the compressor working fluid, and a valve assembly ( 60 ) communicating with the heat engine cylinder chamber ( 34 ) and controlling the ingress and egress of heat engine working fluid ( 18 ) to the heat engine ( 26 ).

Air conditioning system for vehicle

Abstract: An air conditioning system includes a primary or engine-driven compressor that is driven by a primary driving source or engine, and a secondary or motor-driven compressor that is driven by a secondary driving source or motor. The air conditioning system increases in advance an output of the secondary or motor-driven compressor before the primary or engine-driven compressor is stopped. Further, when a load of the secondary or motor-driven compressor becomes a predetermined value while the secondary or motor-driven compressor is in operation, the primary or engine-driven compressor is activated.