Showing papers on "Gas compressor published in 1990"

Rotordynamics prediction in engineering

Abstract: Part 1 Characteristics of rotor elements: disc shaft bearings and seals mass unbalance. Part 2 Simple models - basic phenomena: determination of the model symmetric rotor dissymmetric rotor instability damped rotors. Part 3 Rotor equations - solutions of equations: finite elements of rotor elements equations for monorotors equations for coaxial multirotors solution of equations computer program. Part 4 Towards industrial applications: pseudo-modal method influence of modeling natural frequencies - bearing stiffness diagram transmissibility dual rotor. Part 5 Industrial applications: steam compressor high pressure centrifugal compressor low pressure centrifugal compressor centrifugal compressor fitted with active magnetic bearings power gas turbine industrial steam turbine textile machine spindle jet engine. Part 6 Transient motions: equations and solutions speed of rotation law behaviour of a simple rotor experimental and theoretical results for a three disc rotor behaviour of an industrial rotor. Part 7 Torsion: determination from statics of the minimum shaft radius branched systems in torsion analysis of a branched system in torsion industrial electric motor-centrifugal compressor unit. Part 8 Miscellaneous topics: dissymmetric shaft equations with periodic coefficients axial torque influence.

Design of radial turbomachines

Abstract: Part 1: Outline of the book history and applications the centrifugal compressor the radial turbine non-dimensional parameters for performance assessment and design selection. Part 2 Fundamental fluid mechanics and thermodynamics: the basic equations the dynamics of compressible, perfect gas flow definitions of efficiency loss coefficient definitions stator performance parameters. Part 3 Preliminary design and analysis of centrifugal compressors: non-dimensional parameters for design selection application of basic thermo-fluid dynamics to compressors impeller design diffuser performance, design and analysis. Part 4 Preliminary design and analysis of radial turbines: basic design concepts preliminary design of the rotor performance correlations rotor passage preliminary design of the stator exhaust diffuser. Part 5 Generalised computer based one-dimensional performance prediction: generalised gas dynamic analysis empirical flow models and loss correlations summary of prediction procedure. Part 6 Modelling of compressor impellers with separated flow: performance prediction models application to experimentation. Part 7 Geometric description of turbomachine blades and passages: surface definition by two-dimensional projection functional representation of two-dimensional curves geometry definition by three-dimensional surfaces functional representation of three-dimensional surfaces. Part 8 Computation of internal flows: categorisation of methods calculation domains inviscid solution methods viscous solution methods coupled viscous-inviscid methods modelling of stator flows. Part 9 Special problems associated with turbomachine design and operation: compressor surge and techniques to suppress it high pressure ratio compressors pulse operation of radial turbines variable geometry stator for radial turbines special features of radial turbine rotors turbine rotor cooling size effects and scaling. Appendices: preliminary design of centrifugal compressor impellers - computer program listing, description of the computer program preliminary design of radial turbine rotors - computer program listing, description of the program a summary of the governing equations for three-dimensional fluid flow - the conservation of mass, or continuity, equation, the momentum equation, the energy equation discretisation methods - finite difference, finite element, finite volume.

Stall Inception in Axial Compressors

Abstract: Detailed measurements have been made of the transient stalling process in an axial compressor stage. The stage is of high hub-casing ratio and stall is initiated in the rotor. If the rotor tip clearance is small stall inception occurs at the hub, but at clearances typical for a multistage compressor the inception is at the tip. The crucial quantity in both cases is the blockage caused by the endwall boundary layer. Prior to stall, disturbances rotate around the inlet flow in sympathy with rotating variations in the endwall blockage; these can persist for some time prior to stall, rising and falling in amplitude before the final increase, which occurs as the compressor stalls. © 1990 by ASME.

The Use of an Ejector as a Refrigerant Expander

Abstract: One of the thermodynamic losses in the vapor-compression retr1geration cycle is the throttllng process in the expansion valve. It work is extracted from the refr1gerant during the expansion process, the efficiency of the cycle is swnificantly 1mproved. It 1s proposed that the high-pressure retngerant be used as the motive fluid of a Jet ejector. Instead of extract1ng mechanical work from the expanding refrigerant, 1ts kinetic energy is used to partially compress the saturated vapor leaving the evaporator, increas1ng the enthalpy change in the evaporator and reduc1ng the load on the compressor. A first-order analysis of the cycle performance shows sign1ficant 1ncrease in coeffic1ent of performance and decrease 1n compressor displacement relative to a standard vapor-compresslon cycle. The analysis shows much greater performance changes tor some refrigerants than for others, 1ndicating a potential impact on the selection of new, non-CFC refrigerants. COP h p r s u X q Coetficlent of Performance specific enthalpy pressure motive flow/total flow specific entropy veloc1ty qua.l1ty efficiency IIOIIENCLATURE d tc ge m n s Subscripts: diffuser outlet condenser saturated l1quid evaporator saturated vapor mixing section outlet motive nozzle outlet suction nozzle outlet

Humidity control for variable speed air conditioner

Abstract: An air conditioner system of the type having a variable speed compressor and an indoor heat exchanger having a variable speed fan for controlling the rate of air flow over the evaporator coil has a controller which employs the benefits of variable speed compressors and the variable indoor fan to improve humidity control. During a normal cycle when the relative humidity is below a setpoint, the compressor speed is varied as a function of cooling demand between a minimum compressor speed and full compressor speed. The fan speed is varied generally linearly with the compressor speed between a minimum fan speed and full fan speed. When the humidity level is above the setpoint, the relationship between compressor speed is altered to increase the amount of dehumidification. The minimum compressor speed is increased, while the minimum air flow speed remains the same. The compressor speed is then controlled between this higher minimum speed and full speed, while the fan speed is controlled between minimum fan speed and full fan speed.

Combined turbine stator cooling and turbine tip clearance control

Abstract: The outer air seal of a gas turbine engine is continuously cooled by compressor discharge air (primary) and a by-pass line (secondary) which can be throttled or shut off, augments cooling during high power conditions and is throttled or shut off at reduced power conditions, allowing the casing scrubbed by fan discharged air to shrink and reduce the clearance of the tips of the turbine blades. The air from the continuous flow (primary) line is routed to the outer air seals in a manner to avoid scrubbing the engine case.

Oxygen concentrator with pressure booster and oxygen concentration monitoring

Abstract: In an oxygen concentrator which is intended for aircraft use, a booster compressor is used to increase the pressure of the product gas from the concentrator in order to increase the amount of the gas which can be stored in a plenum. The booster includes two moving pistons which are rigidly linked together and a series of check valves which control the flow of gases through the compressor. One of the pistons is driven by air from the rotary valve in the concentrator, and the other piston compresses the product gas for delivery to the plenum. A small sample of concentrator product gas is monitored by an oxygen sensor for oxygen concentration. Once the oxygen concentration has reached an acceptable level the booster compressor fills the plenum with product gas. Thereafter, if oxygen concentration of product gas delivered to the crew from the concentrator falls below the concentration which is required at a particular altitude, the product gas stored in the plenum is delivered to the crew. The oxygen sensor monitors the concentrator output product gas to the breathing regulator when the stored plenum gas is not being used.

Heat pump systems

Abstract: Heat pump systems (principally FIG. 3; also FIGS. 5, 7 or 9) comprising, in circuit of fluid, an injected compressor 113, communicating a compressed gas discharge 137 to a condenser 100, communicating an at least partly liquid output 130 to an expansion valve 101, communicating therefrom 131 to a separator 110, communicating liquid therefrom 134 to a capillary tube 111, and communicating gas therefrom 132 to a control valve 112 that is responsive to ambient temperature; 111 communicating the liquid therefrom 135 to an evaporator 102, communicating gas therefrom 136 to an inlet of the injected compressor 113; the control valve 112 communicating gas therefrom 133 to an injection input of the injected compressor 113; and the expansive valve 101 being adjustable 176,171 responsive to the temperature of the gas communicating 136 from the evaporator 102 to the injected compressor 113. Where the fluid comprises a non-azeotropic refrigerant blend (NARB), the system (FIG. 5; also FIG. 9) comprises also a heat exchanger 114, having a condenser section 139,140 communicating 138 the fluid from the expansion valve 101 to 131 the separator 110, and an evaporator section 141,142 communicating 136 the fluid from the evaporator 102 to 136' the inlet of the injected compressor 113.

Active Stabilization of Centrifugal Compressor Surge

Abstract: Active suppression of centrifugal compressor surge has been demonstrated on a centrifugal compressor equipped with a servo-actuated plenum exit throttle controller. The control scheme is fundamentally different from conventional surge control techniques in that it addresses directly the dynamic behavior of the compression system to displace the surge line to lower mass flows. The method used is to feed back perturbations in plenum pressure rise, in real time, to a fast acting control valve. The increased aerodynamic damping of incipient oscillations due to the resulting valve motion allows stable operation past the normal surge line. For the compressor used, a 25% reduction in the surge point mass flow was achieved, over a range of speeds and pressure ratios. Time-resolved measurements during controlled operation revealed that the throttle required relatively little power to suppress the surge oscillations, because the disturbances are attacked in their initial stages. Although designed for operation with small disturbances, the controller was also able to eliminate existing, large amplitude, surge oscillations. Comparison of experimental results with theoretical predictions showed that a lumped parameter model appeared adequate to represent the behavior of the compression system with the throttle controller and, perhaps more importantly, to be used in the design of more sophisticated control strategies.Copyright © 1990 by ASME

Heating and cooling apparatus

Abstract: A heating and cooling method and apparatus for a single, closed loop configuration for directly exchanging thermal energy with the earth for both heating and cooling purposes. A refrigerant, which is pumped through the apparatus by a compressor, undergoes two phase transitions during each circuit through the loop. A subterranean heat exchanger has a pair of manifolds in flow communication with a plurality of substantially horizontally oriented tubes. Refrigerant flowing through the tubes has sufficient velocity to sweep lubricant oil, which has escaped from the compressor, along with it for return to the compressor. An expansion valving assembly automatically meters and regulates the flow rate and pressure of the refrigerant during both the heating mode and the cooling mode of the apparatus. A refrigerant storage device automatically supplies or accepts the change in quantity of the refrigerant required when the apparatus changes from either the heating or cooling mode to the reverse mode. A bypass mechanism anticipates the low pressure condition which arises at the compressor input during reversal or startup of the apparatus and provides multiple attempts to overcome inertial resistance corresponding thereto. A modified embodiment of the apparatus provides a non-phase-change heat exchanger flow communicating in tandem to remove a portion of the thermal energy for auxiliary thermodynamic purposes.

Air comfort pillow

Abstract: A sleeping pillow having an inflatable air bag and a built-in air compressor and air exhaust control mechanism, such that the softness or hardness of the pillow can be regulated to meet individual requirements. The air compressor is powered by dry cell batteries that are located within a housing for the compressor. The air compressor housing is located within a pocket at one end of the pillow.

Compressor with liquid injection

Abstract: A refrigeration system incorporating a scroll type compressor is disclosed which includes an injection system for injecting liquid refrigerant into the suction inlet opening of the compressor in response to excessive discharge gas temperature. A temperature sensor assembly is located within a well formed in the discharge chamber and serves to control actuation of the liquid injection system. In one embodiment the sensor assembly incorporates a pair of thermostats, one to control liquid injection and one to shut down the compressor in the event of continued overheating. In another embodiment a single thermostat having two tip temperatures is utilized. In a third embodiment a temperature sensing transducer is utilized in combination with a microprocessor.

An electronic control for monitoring status of a compressor

Abstract: The compressor controller (100) includes a timing circuit (106) for timing-out a detected fault in a compressor (111). Upon the fault existing for longer than a predetermined time limit, the controller (100) removes power from the compressor (111). If the fault is corrected within the predetermined time limit, even momentarily, the timing process is discontinued and the controller continues to monitor the status of the compressor. The controller also includes a delay timer (108) for delaying the re-energizing of the compressor (111) after an interruption or loss of power occurs. The delay prevents short cycling of the compressor. The controller (111) further includes a status display (104) for indicating compressor functions, connections to an alarm which is initiated in the event of compressor failure, a switch for initiating a self test of the controller, and circuitry for a field applied current sensing relay.

Compressor diaphragm assembly

Abstract: A compressor diaphragm assembly (64) for combustion turbines includes a plurality of vanes (66), each of which is formed with an integral inner shroud (68) and an integral outer shroud (70), joined together by connecting bars (74) fitted into grooves (72) in the shrouds (68, 70) of the vanes (66) so as to provide for transfer of loads between the vanes (66).

Combination propulsion system for a flying craft

Abstract: A combination engine for a flying craft capable of flying at speeds within a wide range from subsonic speeds to hypersonic speeds, is equipped with a rocket engine section that is independent of an atmospheric air supply, and a turbo air jet engine section having a compressor which is driven by a turbine that is also independent of an external air supply. The combination may further include extra fuel supply nozzles for operation as a ram jet which uses the same flow channel as the turbo air jet engine section. A gas generator equipped with two valving mechanisms is arranged coaxially with the rocket engine section. The valving mechanisms are controllable to open the gas generator chamber to the rocket combustion chamber while closing off gas flow to the turbo air jet section or vice versa. Either section can work alone or in parallel and simultaneously with the other section. Each turbine wheel forms with one compressor wheel a free wheeling rotor without any intermediate guide wheels, whereby the turbine blades extend either radially inwardly or radially outside of the compressor blades. A gas mixer or distributor is arranged downstream of the turbine and leads into the combustion chamber of the turbo or ram jet section to mix external air with the turbine propellant gases.

Low refrigerant charge protection method for a variable displacement compressor

Abstract: A low charge protection method for an electronically controlled variable displacement compressor. In each period of compressor operation, a low charge test sequence is carried out to monitor the system performance once the system control pressure has been reduced below a specified level. In a set-up phase of the test, the compressor is down-stroked to near-minimum displacement for a predetermined time or until the system control pressure rises above a reference level. At such point, the compressor is up-stroked to near-maximum displacement to initiate a pull-down phase of the test. If the system pressure is reduced by specified amount within a reference interval, a failed test is indicated and the count in a nonvolatile counter is incremented. If the pull-down duration exceeds the reference interval, a passed test is indicated, and the count, if any, is decremented. When the nonvolatile count exceeds a specified threshold, the compressor is disabled and further operation is prevented until the count is reset by a service technician.

Liquefaction of natural gas using process-loaded expanders

Abstract: A process for the liquefaction of natural gas is disclosed wherein expansion valves for low-level multicomponent refrigerant and liquefied gas product streams are replaced with process-loaded turboexpanders having liquid inlet streams. Each turboexpander is coupled with a compressor or pump so that expansion work extracted from a given stream is used directly to compress or pump the stream prior to cooling and expansion. The use of process-loaded turboexpanders reduces the minimum work of liquefaction and increases the liquefaction capacity of the process.

Internal combustion engine with a dual turbocharger system

Abstract: An internal combustion engine with a dual turbocharger system includes an air bypass conduit connecting a downstream portion of a first turbocharger compressor with an upstream portion of a second turbocharger compressor so that the length of the air bypass conduit is relatively long. When a throttle is rapidly closed, an air bypass valve installed in the air bypass conduit is opened and the compressed air downstream of the throttle valve is returned to the upstream of the turbocharger compressor to suppress occurrence of a surging at the turbocharger compressor. Since the air bypass conduit is relatively long, the compressed and circulated air is effectively cooled when flowing through the air bypass conduit and melting of an impeller of the turbocharger compressor is prevented.

The Impact of Atmospheric Conditions on Gas Turbine Performance

Abstract: This paper is devoted to studying the impact of atmospheric conditions, such as ambient temperature, pressure, and relative humidity on gas turbine performance. A fully interactive computer program based on the derived governing equations is developed. The effects of typical variations of atmospheric conditions on power output and efficiency are considered. The thermal efficiency and specific network of a gas turbine were calculated at different values of maximum turbine inlet temperature and variable environmental conditions

Turbo-charger with rotary machine

Abstract: A turbo-charger (120) with a rotor directly connected thereto has a turbine impeller (1b), a turbine shaft (1a) secured to the turbine impeller (1b) and a compressor secured to the turbine shaft and driven thereby to forcibly feed air into an internal combustion engine (107). The rotor (3a) is provided on the turbine shaft (1a) and so structured as to prevent the occurrence of an unbalanced condition during rotation of the turbine shaft (1a).

Air cycle air conditioner for heating and cooling

Abstract: A compact, air cycle air conditioning system including compressor, turbine, heat exchanger and high speed electric motor is thermostatically controlled to supply either hot or cold conditioned air to a load air space. In a second arrangement, compact, exhaust gas driven air cycle air conditioning system including a compressor, turbine, two heat exchangers and an exhaust turbine is controlled by means of an exhaust gas bypass arrangement and supplies either hot or cold conditioned air to a load air space. In a third arrangement compact, exhasut gas driven air cycle air conditioning system includes an expansion turbine, two compressors, two heat exchangers and an exhaust turbine which is preferably controlled by means of an exhaust gas bypass arrangement and supplies either hot or cold conditioning air to a load air space.

Prediction and Measurement of Film Cooling Effectiveness for a First-Stage Turbine Vane Shroud

Abstract: After compressor discharge air has initially been used to cool the heat shields of the hot gas inlet casing, it can subsequently be employed for film cooling of the first-stage vane shrouds. Since the flow field near these shrouds is three-dimensional, the film cooling effectiveness cannot be predicted correctly by common two-dimensional codes. The secondary flow transports the film from the pressure side to the suction side where it can even climb up the airfoil to cool its trailing section.Such film cooling effectiveness was first investigated experimentally in a linear vane cascade at atmospheric pressure. The temperatures and static pressure levels at the adiabatic shrouds, as well as the temperature measurements within the vane cascade, are reported for different cooling film blowing rates.In addition, the secondary flow was analysed numerically using a partially-parabolic computer code for 3D viscous flows. It involves mutual interaction of the boundary layer with the mainstream. The secondary flow can also be modelled with this algorithm, which requires less numerical effort than solving the fully 3D elliptic flow equations. The numerical results of the experiment and numerical predictions are compared. In addition, the application of these results to a high-temperature gas turbine is presented.Copyright © 1990 by ASME

Cogeneration system with recuperated gas turbine engine

Abstract: A turbine engine is provided with a primary surface, counterflow heat exchanger for preheating the compressed air from the compressor prior to its entry into the combustor. The recuperator includes three concentric cylindrical shells which completely encircle the hottest components of the engine. The outermost shell includes a plurality of inlet openings for receiving air from the compressor, and a plurality of outlet openings for discharging the air into the combustor. The innermost shell includes a plurality of inlet openings for receiving gases from the turbine and a plurality of outlet openings communicating with an exhaust duct. The central shell is a corrugated tube which divides the space between the inner and outer shells into a plurality of concentric annular flow chambers, and allows heat transfer between adjacent chambers. Annular turbulators may be inserted in the chambers. The engine may be used in a cogeneration system in which the exhaust duct is coupled to a boiler, and a temperature-controlled valve is provided for controlling the proportion of exhaust gases entering the recuperator relative to those directly entering the boiler. The engine may also be used in a system using intercooling and reheating, or integrated with an air cycle in which it is used to cool water.

Counterflow single rotor turbojet and method

Abstract: A small gas turbine engine for generating thrust and shaft horsepower is provided. The engine is comprised in a flow series arrangement of an inlet, a diffuser, a single stage compressor, a fuel slinger combustor, a single stage turbine, and an exhaust nozzle. The compressor circumscribes the turbine and is mounted on the same rotating wheel so that the flow of air in the compressor is in the direction opposite to the direction of hot gas flow in the turbine. Accordingly, both the compressor and turbine are on the same side of the combustor and hence only a single bearing support structure is required.

Electric power demand limit for variable speed heat pumps and integrated water heating heat pumps

Abstract: An integrated heat pump and hot water system provides heating or cooling of a comfort zone, as required, and also provides water heating. As a power management feature, the speed of a variable speed compressor is reduced to a predetermined fraction, e.g. 80%, of its normal operating speed, in response to a demand limit signal provided from the electric power utility during times of peak electrical load. A reference compressor speed is computed based on the current compressor speed, indoor temperature, outdoor temperature, and zero-load temperature difference. If the system is between operating cycles when the demand limit signal is received, a stored speed is used which corresponds to the compressor speed at a predetermined outdoor-indoor temperature difference. This system produces graceful reduction in comfort cooling during demand limit periods.

Capacity controllable compressor apparatus

Abstract: A capacity controllable compressor apparatus has a plurality of high-pressure chamber compressors (1, 2, 3; 27, 28; 33, 34) which are connected in parallel to a common refrigerant suction pipe (10) and a common refrigerant discharge pipe (11), and oil equalizing pipes (15a, 15b; 15) through which oil sumps (1b, 2b, 3b; 27b, 28b; 33b, 34b) of the plurality of compressors are communicated with each other. One of the plurality of compressors (1, 2, 3; 27, 28; 33, 34) is operated with its chamber kept at a higher internal pressure than other compressors. The compressor apparatus comprises an oil separator (16) disposed to the common discharge pipe (11); device (17a, 17b, 17, 18, 29, 30, 32) for returning lubricating oil separated by the oil separator (16) to a suction side of one of the compressors operated with its chamber kept at a higher internal pressure; first control device (22a, 22b; 23) disposed in the oil equalizing pipes (15a, 15b; 15) so as to prevent the lubricating oil from flowing into one of the two compressors communicated with each other by the oil equalizing pipe, said one being made inopera­tive when the capacity of the compressor apparatus is controlled; and valve device (20a, 20b; 20; 20, 24) disposed in a discharge pipe (4, 5) of the inoperative compressor so as to prevent refrigerant from flowing into the inoperative compressor.

High-temperature fuel cells with oxygen-enriched gas

Abstract: In high-temperature fuel cells based on an ion-conducting electrolyte, wherein hydrogen and oxygen are converted into water, the cathode of the fuel cell is supplied with oxygen-enriched gas from an air separator, preferably a cryogenic air separator. This oxygen-enriched gas is supplied together with a CO2 -containing gas in a stoichiometric O2 /CO2 ratio. For the recovery of the O2 and CO2 components, a partial stream of the cathode outlet gas is recycled; for this purpose, the cathode outlet gas, used for regulating the fuel cell temperature, is cooled with production and/or superheating of steam and recompressed by means of a hot gas blower or a hot gas compressor.

Aircraft engine starter integrated boundary bleed system

Abstract: An aircraft gas turbine engine is provided with a compressed air supply system generally used for meeting customer or aircraft bleed air requirements. The compressed air supply system comprises an auxiliary compressor, a means for mechanically driving the system from a rotor of the gas turbine rotor, and a cycle varying means, such as a variable speed drive, for operating the auxiliary compressor cycle independently of the aircraft gas turbine engine compressor cycle. The preferred embodiment provides a means for bleeding boundary layer air off the nacelle or another part of the aircraft outer skin and using it as a source of air for the auxiliary compressor. One embodiment includes an air turbine on a common shaft with the auxiliary compressor and a means to direct an unused portion of the airflow form the auxiliary compressor to the air turbine to help power the auxiliary compressor and another embodiment includes a means to direct compressed startling air to the air turbine for on ground and in flight starting of the gas turbine engine through the variable speed drive and a mechanical linkage to the high rotor of the gas turbine engine.

Chemically recuperated gas turbine

Abstract: A powerplant comprising a compressor for producing a downstream fluid flow, a combustor downstream of the compressor, a turbine downstream of the combustor, a power turbine downstream and adjacent the turbine, and a duct region which receives at least a portion of the fluid output of the power turbine. A reformer is positioned downstream and is coupled to the duct region and the reformer has a fuel outlet which is coupled to the combustor.