Showing papers on "Gas compressor published in 1993"

Human lung ventilator system

Abstract: A patient ventilator system provides a controllable flow and volume of a mixed inhalation gas to a patient, and receives exhaled gas from the patient. The ventilator system includes gas flow controllers that mix air and oxygen, and provide the mixture to the patient with a controllable inhalation cycle. The ventilator system monitors the resulting patient pressures and volume of gas exhaled by the patient, as necessary. Compressed air is provided to the gas controller in the event of an absence of an external gas supply by a compressor. A controller permits the user of the ventilator system to control ventilation mode, gas pressure, composition, and flow rate of the mixed gas with a single control knob.

Active control of rotating stall in a low-speed axial compressor

Abstract: The onset of rotating stall has been delayed in a low-speed, single-stage, axial research compressor using active feedback control. Control was implemented using a circumferential array of hot wires to sense propagating waves of axial velocity upstream of the compressor. Using this information, additional circumferentially traveling waves were then generated with appropriate phase and amplitude by «wiggling» inlet guide vanes driven by individual actuators. The control scheme considered the wave pattern in terms of the individual spatial Fourier components. A simple proportional control law was implemented for each harmonic. Control of the first spatial harmonic yielded an 11 percent decrease in the stalling mass flow, while control of the first, second, and third harmonics together reduced the stalling mass flow by 23 percent

Control system for an air conditioning/refrigeration system

Abstract: A microprocessor-based air conditioning/refrigeration control system (76) adapted for use with a variable speed compressor (12) measures acceleration (N1) of the compressor and the temperature (T2) or pressure (P2) of the refrigerant exiting therefrom, determines the rate of change of the temperature or pressure of the refrigerant, and decreases acceleration of the compressor if the rate of change of the temperature or pressure of the working fluid indicates surging of the compressor. Superheat (T1, P1) of the refrigerant is maintained at a first predefined level while the compressor is operating at constant speed (N1) and is increased to a second, higher predefined level while the compressor is accelerating. The system is able to diagnose deterioration of the compressor by measuring and comparing power input (V,A) to the compressor and rate of change of temperature (T2) or pressure (P2) of the refrigerant at the compressor between initial and subsequent periods, and differentiate between deterioration of a drive component or a pressurizing component of the compressor.

Gas turbine engine cooling system

Abstract: PURPOSE: To provide a gas turbine engine cooling system realizing improved cooling of high-temperature constituent portions and other portions. CONSTITUTION: A turbocompressor 128 and a heat exchanger 130 are fluidly interconnected and are each in fluid communication to receive air of differing pressures and temperatures. Typically, such air is received from various regions of an engine low pressure compressor and an engine high pressure compressor. A cooling system 110' delivers air through a duct 126 to a portion of the engine for cooling, such as the engine high pressure turbine region, at lower temperatures and higher pressures than if cooling air were directly ducted from the engine compressor to the engine turbine.

System and method for operating a respiration compressor system under low voltage conditions

Abstract: The system and method for operating an AC respirator compressor system at substantially subnormal line voltages includes a compressor (4), an accumulator (6), a solenoid unload or dump valve (12) used to reduce the pressure at the outlet of the compressor, a check valve (10) located downstream from the solenoid, a relief valve (8), a pressure sensor (14), and an AC voltage sensor (18). In a preferred embodiment, the compressor constantly supplies compressed air to the ventilator system, monitoring the accumulator pressure and activating the solenoid unload valve as required to maintain an acceptable range of pressure in the accumulator. In another preferred embodiment the compressor system can also be operated in an intermittent, or standby mode, to supply compressed air as needed. The respirator compressor system can maintain an acceptable range of pressure in the accumulator even during periods of low AC line voltage by monitoring both the accumulator pressure and the AC line supplying voltage to the respirator compressor system, and modulating the action of the solenoid unload valve to achieve low AC voltage operation.

Gas turbine engine variable bleed pivotal flow splitter

Abstract: The present invention provides a gas turbine engine with a circumferentially disposed plurality of pivotal flow splitters between compressor sections to bleed off flow and remove particles, particularly ice in the case of an aircraft fan-jet gas turbine engine, by pivoting the leading edge of the splitter into the compressor flow thereby using the total pressure Q of the flow to drive bleed flows overboard and remove particles In the preferred embodiment the pivotal flow splitter is integral with a booster variable bleed valve (VBV) door, and includes a booster bleed duct means having a bellmouth shaped inducer type inlet to enhance the capture of compressor flow and particle removal

Process and device for monitoring and for controlling of a compressor

Abstract: A process and a device for monitoring and controlling a compressor (10) by measuring pressure fluctuations within at least one stage of the compressor (10) in the region of the housing (24) of the compressor (10) by means of at least one pressure sensing device (32), deriving a frequency signal which comprises at least one characteristic peak (70) in a region of a characteristic frequency assigned to one of the compressor stages (12, 14) and determining at least one peak parameter indicative of the operational status of the compressor (10), and generating a status change signal in case the peak parameter lies beyond a predetermined value range, which is used for controlling the compressor (10).

Method and apparatus for delivering a continuous quantity of gas over a wide range of flowrates

Abstract: Method and apparatus for delivering high pressure gas to a point of use over a wide range of flowrates by storing said gas as a cryogenic fluid, removing said cryogenic fluid by means of a single stage reciprocating piston-type pump/compressor adapted to utilize liquid, vaporized liquid, a mixture of liquid and vaporized liquid, or supercritical fluid as the inlet fluid to said pump while maintaining the inlet fluid under cryogenic conditions. Blowby from the pump is recycled to the system. Discharge fluid may also be recycled to the system.

Aircraft cooling method

Abstract: A method for supplying cooling air on vehicles such as high speed aircraft includes diverting high pressure air from the compressor section of a gas turbine engine, cooling this air in a heat exchanger, and expanding the diverted high pressure air through an auxiliary turbine. Coolant in the heat exchanger may be inlet ram air, fan air, or aircraft fuel (which may be endothermic), and the coolant is ultimately introduced into the engine downstream of the compressor section. An auxiliary compressor may be used to further compress the diverted high pressure air or coolant prior to the flowing thereof through the heat exchanger, and one or more auxiliary turbines may be used to power the auxiliary compressor, or mechanical accessories on the vehicle.

Scroll compressor with liquid injection

Abstract: A scroll-type refrigerant compressor for use in a conventional refrigerating circuit and having liquid refrigerant compressor cooling provided by the injection of liquid refrigerant into an intermediate biasing chamber and/or specifically located bleed holes.

Solar venturi turbine

Abstract: A solar venturi turbine includes an upwardly oriented venturi tube supported by a venturi support skirt. The venturi tube includes a tapered thermopane glass enclosure which allows sunlight to project therethrough and impinge on a tapered centrifugal fan fronting the thermopane enclosure and mounted within the venturi tube. Located above the centrifugal fan in the neck of the venturi tube is a high velocity fan. A high pressure compressor is mounted above the high velocity fan, and finally a turbine is mounted above the high pressure compressor. A venturi tube outlet flares outwardly directly above the turbine and is mounted to the venturi tube. The turbine is connected to a shaft to drive an electrical generator thereby producing electricity. The sun's rays heat the air within the thermopane glass enclosure causing the reduced density air to rise within the venturi tube and propel the centrifugal fan. The air continues upwardly through the high speed fan and the high pressure compressor increasing in velocity and finally passing through and turning the turbine which is connected to the generator by the turbine shaft. Initial start-up of the solar venturi turbine is with a motor which turns both fans and the high pressure compressor. The solar venturi turbine provides a clean and environmentally harm-free source of electricity without diminishing fossil fuel reserves.

Air-start assembly and method

Abstract: A method and assembly are effective for air-starting an aircraft gas turbine engine having a fan powered by a low pressure turbine through a first shaft, and a compressor powered by a high pressure turbine through a second shaft disposed coaxially therewith. A gear train is selectively operatively joined between the first and second shafts by selectively engaging a first clutch for transmitting torque through the first clutch only in one direction from the first shaft to the second shaft when the fan is windmilling for driving the second shaft to allow an air-start of the gas turbine engine during flight. In a preferred embodiment, a second clutch is operatively joined to the gear train and is selectively engageable at speeds of the second shaft below a predetermined release speed, and disengageable at the release speed and above for disconnecting the air-start assembly once the engine has been started.

Numerical simulation of compressor endwall and casing treatment flow phenomena

Abstract: A numerical study is presented of the flow in the endwall region of a compressor blade row, in conditions of operation with both smooth and grooved endwalls. The computations are first compared to velocity field measurements in a cantilevered stator/rotating hub configuration to confirm that the salient features are captured. Computations are then interrogated to examine the tip leakage flow structure since this is a dominant feature of the endwall region. In particular, the high blockage that can exist near the endwalls at the rear of a compressor blade passage appears to be directly linked to low total pressure fluid associated with the leakage flow. The fluid dynamic action of the grooved endwall, representative of the casing treatments that have been most successful in suppressing stall, is then simulated computationally and two principal effects are identified. One is suction of the low total pressure, high blockage fluid at the rear of the passage. The second is energizing of the tip leakage flow, most notably in the core of the leakage vortex, thereby suppressing the blockage at its source.

Experimental and Computational Investigation of the NASA Low-Speed Centrifugal Compressor Flow Field

Abstract: An experimental and computational investigation of the NASA Lewis Research Center's low-speed centrifugal compressor (LSCC) flow field was conducted using laser anemometry and Dawes' three-dimensional viscous code. The experimental configuration consisted of a backswept impeller followed by a vaneless diffuser. Measurements of the three-dimensional velocity field were acquired at several measurement planes through the compressor. The measurements describe both the throughflow and secondary velocity field along each measurement plane. In several cases the measurements provide details of the flow within the blade boundary layers. Insight into the complex flow physics within centrifugal compressors is provided by the computational fluid dynamics analysis (CFD), and assessment of the CFD predictions is provided by comparison with the measurements. Five-hole probe and hot-wire surveys at the inlet and exit to the impeller as well as surface flow visualization along the impeller blade surfaces provided independent confirmation of the laser measurement technique. The results clearly document the development of the throughflow velocity wake that is characteristic of unshrouded centrifugal compressors.

Multi-temperature evaporator refrigerator system with variable speed compressor

Abstract: A refrigeration appliance is provided having at least two refrigeration compartments, each compartment having its own access door. The appliance includes a single evaporator located in a plenum which is selectively in communication with each of the compartments, a single compressor, preferably run by a variable speed motor, and a refrigerant circuit including a series of conduits for providing a flow of refrigerant to the evaporator and compressor. A first restriction device is provided in the conduit connecting the compressor with the evaporator, the restriction device operating at a first pressure level. A second restriction device is also provided in the conduit connecting the compressor with the evaporator, preferably in parallel with the first restriction device, the second restriction device operating at a pressure level higher than the first pressure level. Also, a valve or valves preferably of the latching kind, is positioned in the refrigerant circuit for directing refrigerant to a selected one of the restriction devices, or closing both circuits entirely. A phase change material may be used in the refrigeration circuit, downstream of the restriction devices to improve energy efficiency of the system. Also, with this system, the compartments of the refrigerator appliance can be run either in freezer or in fresh food cooling mode as desired, providing convertible refrigerating compartments.

Multistage membrane control system and process

Abstract: The invention relates to the control of multistage fluid separation processes and systems. The processes and systems employ at least one recycle compressor or pump in conjunction with their associated controlling system to separate a fluid mixture in an efficient manner during off demand or turndown conditions. The operation of at least one recycle compressor or pump is controlled so as to maintain the pressure in the permeate side or sides at a set value, thus maintaining the desired pressure ratio across the multistage membrane and obtain the desired, reduced power consumption during off demand or turn-down conditions.

Integrated refueling system for vehicles

Abstract: An integrated refueling system comprises a fluid circuit including multiple flow paths for directing natural gas to a natural gas liquefier. A portion of the resulting liquefied natural gas is provided to a liquefied natural gas delivery location. Another portion of the liquefied natural gas may be provided to a compressor and subsequently a heat exchanger/vaporizer to produce compressed natural gas. The heat exchanger/vaporizer may utilize the lower temperature of liquefied natural gas to precool incoming gaseous natural gas while simultaneously vaporizing the pressurized, liquefied natural gas to form the compressed natural gas. Compressed natural gas may be provided at a compressed natural gas delivery location.

Method for liquefying natural gas

Abstract: Provided is a method for liquefying natural gas which can be readily adapted to LNG plants of all sizes without requiring expensive and special heat exchangers. The liquefaction of feed gas of natural gas and recycle natural gas is carried out with a single-component refrigerant or a mixed refrigerant in a high temperature stage, and with a substantially isentropic expansion in a low temperature stage, and a non-liquefied part of the recycle gas after the expansion step is pressurized with a compressor and recycled along with a recycle stream of non-liquefied par of the feed natural gas, the liquefied part by the refrigerant exchanging heat with the non-liquefied part stream produced from the substantially isentropic expansion, in a plate-fin heat exchanger or the like. The compressor is driven by the power obtained by the substantially isentropic expansion.

Low capacity centrifugal refrigeration compressor

Abstract: An improved motor driven centrifugal refrigerant compressor is disclosed having a housing enclosing a motor, control electronics and moving parts of the compressor, and a fluid pathway for circulating a mixture of low pressure refrigerant and a lubricant around the pathway, the pathway including a lubricant concentrator for coalescing the lubricant of the mixture to lubricate moving parts of the compressor and the pathway also including a convective heat transfer region to cool the motor and control electronics within the housing.

Turbo machine with an axial dry gas seal

Abstract: In a turbo machine, for example, a turbo compressor, the rotor shaft extends through and is sealed relative a housing via dry gas seals in which a seal clearance is achieved between a rotating, sealing body and a non-rotating sliding body in which the inner side of the dry gas seal is charged with a barrier gas, with the leakage of the dry gas seal being dammed via a back-up plate and the dynamic pressure is monitored via a pressure inspection device, wherein due to increasing dynamic pressure an alarm is given off or the turbo machine is automatically shutdown without delay so that the exit of gas, particularly of toxic or explosive gas from the inner area of the housing of the turbo machine is avoided, wherein, via the use of multiple seals the leakage pressure of one of the inner dry gas seals can initiate a warning or alarm signal and via the leakage pressure of the outer dry gas seal, the turbo machine can be shut down.

Swash plate type compressor

Abstract: A swash plate type variable capacity compressor having rotary valves that rotate together on a rotating shaft. The rotary valves are arranged on the shaft in such a manner that, upon one complete rotation, the rotary valves are connected, in sequential manner, for respective rotating angles, with circumferentially spaced piston chambers via respective intake passageways on the rotary valves. The arrangement between the intake passageways and the piston chamber changes in accordance with the axial position of the rotary valves on the shaft. Control of the rotating angle varies the effective volume of the piston chambers, thereby continuously varying the compressor capacity.

Air conditioning apparatus

Abstract: A refrigerating circuit of an air conditioning apparatus has a refrigerating circuit which is formed with a compressor, an expansion valve, a first heat-exchanger and a second heat-exchanger. The amount of the refrigerant in the refrigerating circuit is controlled by the expansion valve which is controlled by a control unit. The control unit is provided with detector means including various sensors for detecting the ambient temperature, saturation temperature of the refrigerant in the refrigerating cycle, temperature of the discharged refrigerant fed from the compressor, etc. Detection of refrigerant leakage from the refrigerating circuit is accurately performed by the detector means. Control means responsive to the detector means controls the operation of the compressor. The compressor is stopped when the ambient temperature is within a pre-determined level and the discharged temperature exceeds a given level if the opening of the expansion valve is full. Malfunction of the compressor is thus prevented.

Power augmentation of a gas turbine by inlet air chilling

Abstract: In order to augment the power produced by a gas turbine system of a type having an air compressor for producing compressed air, a combustor for heating the compressed air, and a gas turbine responsive to the heated air for driving the air compressor and the load, cooling air is supplied to the compressor by indirectly contacting the air with water that is chilled by flashing some of the water into a vapor.

Air cycle machine with magnetic bearings

Abstract: An air cycle machine for producing a supply of cooled air and including a compressor rotor fixed to a shaft which is driven by a turbine rotor, the turbine serving to expand air which is pressurized by the compressor. Magnetic bearings support the shaft radially in a housing for rotation about a precisely established axis while a magnetic thrust bearing keeps the shaft in a precisely fixed axial position. The housing and the bearings are constructed as two split sections to permit the housing and the bearings to be separated radially and facilitate repair and/or replacement of the shaft and other internal components.

Process and device for monitoring vibrational excitation of an axial compressor

Abstract: A process and a device for monitoring vibrational excitation of an axial compressor (10) by measuring of pressure fluctuation within at least one stage (12, 14) of said compressor (10) in the region of the compressor housing (24) by means of at least one pressure sensing device (32), checking whether each of said frequency signals comprises at least one excitation peak within a predetermined frequency interval in a region of at least one critical frequency of said compressor (10), determining at least one peak parameter indicative of the excitation status of the compressor (10) and generating a status change signal in case said peak parameter has a value lying beyond a predetermined value range.

Variable speed HVAC without controller and responsive to a conventional thermostat

Abstract: A system for conditioning air in a space by heating or cooling the air to change its temperature. A thermostat located within the space generates a two state temperature signal having a cyclic parameter which corresponds to the temperature of the air in the space as it rises and falls. A compressor supplies refrigerant to a heat exchanger by means of which changes are made in the temperature of the air. A variable speed motor drives the compressor in response to a motor control signal. A controller responds to the temperature signal and senses the cyclic parameter of the temperature signal. The controller generates the motor control signal as a function of the sensed cyclic parameter whereby the motor control signal is provided to the motor to control the torque or speed of the motor.

Radial compressor for vehicle exhaust gas turbocharger - uses feed pipe to deliver flow medium to influence conditions in circulation chamber

Abstract: The radial compressor has an arrangement for influencing the main flow where a flow medium connection (70) runs into the circulation chamber (14) via one or more bores (73) in the housing (10). The bore opens into one or more places in the circulation chamber. A flow medium can be introduced through the flow medium connection to give a required condition in the circulation chamber. USE/ADVANTAGE - Allows flows conditions in exhaust gas turbocharger to be varied to increase torque at low engine speeds and to reduce exhaust gas emissions.

Dual temperature control of refrigerator-freezer

Abstract: A dual compartment single evaporator refrigerator and temperature control apparatus that effectively controls two compartment temperatures by making the evaporator fan control independent of the compressor cycle. The compressor cycle is initiated by the fresh food compartment temperature, runs for a predetermined minimum time, and is terminated by the freezer temperature. The evaporator fan runs with the compressor and is terminated by the freezer control temperature. A small portion of the evaporator air circulation flows through the fresh food compartment and compartment temperatures are balanced according to the freezer temperature settings during the post-compressor cycle fan control. The temperature control set points to operate the compressor and fan are based on algorithms that compensate the control for the combination of freezer and fresh food temperature settings.

Active Stabilization of Rotating Stall in a Three-Stage Axial Compressor

Abstract: A three-stage, low speed axial research compressor has been actively stabilized by damping low amplitude circumferentially travelling waves which can grow into rotating stall. Using a circumferential array of hot wire sensors, and an array of high speed individually positioned control vanes as the actuator, the first and second spatial harmonics of the compressor were stabilized down to a characteristic slope of 0.9, yielding an 8% increase in operating flow range. Stabilization of the third spatial harmonic did not alter the stalling flow coefficient. The actuators were also used open loop to determine the forced response behavior of the compressor. A system identification procedure applied to the forced response data then yielded the compressor transfer function. The Moore-Greitzer, 2-D, stability model was modified as suggested by the measurements to include the effect of blade row time lags on the compressor dynamics. This modified Moore-Greitzer model was then used to predict both the open and closed loop dynamic response of the compressor. The model predictions agreed closely with the experimental results. In particular, the model predicted both the mass flow at stall without control and the design parameters needed by, and the range extension realized from, active control.Copyright © 1993 by ASME

Measurement of the Three-Dimensional Tip Region Flow Field in an Axial Compressor

Abstract: A two-color, five-beam LDV system has been configured to make simultaneous three-component velocity measurements of the flow field in a two-stage axial compressor model. The system has been used to make time-resolved measurements both between compressor blade rows and within the rotating blade passages in an axial compressor. The data show the nature and behavior of the complex, three-dimensional flow phenomena present in the tip region of a compressor as they convect downstream. In particular, the nature of the tip leakage vortex is apparent, being manifested by high blockage as well as the expected vortical motion. The data indicate that the radial flows associated with the tip leakage vortex begin to decrease while within the rotor passage, and that they temporarily increase aft of the passage