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Showing papers on "Gas compressor published in 2001"


Patent
13 Jun 2001
TL;DR: In this paper, an adjustable throttle device is provided upstream from the compressor wheel, for regulating the air mass stream to be supplied by an exhaust gas turbocharger for an internal combustion engine.
Abstract: An exhaust gas turbocharger for an internal combustion engine has an exhaust gas turbine in the exhaust gas train and a compressor in the intake tract, whereby an adjustable throttle device is provided upstream from the compressor wheel, for regulating the air mass stream to be supplied. The throttle device comprises a first guide grid and a second guide grid in the inflow region to the compressor wheel. Each guide grid possesses an adjustable grid geometry.

371 citations


Patent
06 Sep 2001
TL;DR: An exhaust gas recirculation type gas turbine apparatus as discussed by the authors includes a compressor for compressing air, a combustion chamber for burning fuel and compression air exhausted from the compressor, a gas turbine driven by exhaust gas from the combustion chamber, a path for recirculating a part of the exhaust gas to an intake of the compressor.
Abstract: An exhaust gas recirculation type gas turbine apparatus includes a compressor for compressing air, a combustion chamber for burning fuel and compression air exhausted from the compressor, a gas turbine driven by exhaust gas from the combustion chamber, a recirculation path for recirculating a part of the exhaust gas to an intake of the compressor, a recirculation amount control unit for adjusting the amount of exhaust gas to be returned to the intake of the compressor corresponding to a change in load of the gas turbine, and a spray unit for introducing liquid droplets into the interior of the compressor in which mixing gas, consisting of gas turbine exhaust gas passing through the recirculation path and air, flows so as to vaporize the introduced liquid droplets appearing to flow in the compressor.

262 citations


Journal ArticleDOI
TL;DR: In this article, an experimental and numerical investigation aimed at understanding the mechanisms of rotating instabilities in a low speed axial flow compressor was carried out with high-resolution pressure measurements at different clearances.
Abstract: This paper reports on an experimental and numerical investigation aimed at understanding the mechanisms of rotating instabilities in a low speed axial flow compressor. The phenomena of rotating instabilities in the current compressor were first identified with an experimental study. Then, an unsteady numerical method was applied to confirm the phenomena and to interrogate the physical mechanisms behind them. The experimental study was conducted with high-resolution pressure measurements at different clearances, employing a double phase-averaging technique. The numerical investigation was performed with an unsteady 3-D Navier-Stokes method that solves for the entire blade row. The current study reveals that a vortex structure forms near the leading edge plane. This vortex is the result of interactions among the classical tip-clearance flow, axially reversed endwall flow, and the incoming flow. The vortex travels from the suction side to the pressure side of the passage at roughly half of the rotor speed. The formation and movement of this vortex seem to be the main causes of unsteadiness when rotating instability develops. Due to the nature of this vortex, the classical tip-clearance flow does not spill over into the following blade passage. This behavior of the tip-clearance flow is why the compressor operates in a stable mode even with the rotating instability, unlike traditional rotating stall phenomena.Copyright © 2001 by ASME

214 citations


Journal ArticleDOI
TL;DR: In this article, the authors presented two numerical models to simulate the transient and steady state behavior of a vapor compression refrigeration system, where the condenser and the evaporator were divided into a number of control volumes.
Abstract: This work presents two numerical models to simulate the transient and steady state behavior of a vapor compression refrigeration system. The condenser and the evaporator were divided into a number of control volumes. Time dependent partial differential equations system was obtained from the mass, energy and momentum balances for each control volume. As the expansion valve and the compressor both have very small thermal inertia, the steady state models were applied for these components. Transient and steady state models numerical predictions were compared and good agreement was found. Further simulations were performed with the objective of verifying the possibility of controlling the refrigeration system and the superheating of the refrigerant in the evaporator outlet by varying the compressor speed and the throttling valve sectional area. The results indicate that the proposed models can be used to formulate an algorithm for controlling a refrigeration system.

202 citations


Journal ArticleDOI
Rainer Kurz1, Klaus Brun1
TL;DR: In this article, the effects of degradation on the performance of a gas turbine systent degradation are discussed. But the authors focus on the degradation of the engine and not on isolated components.
Abstract: Any prime mover exhibits the effects of wear and tear over time. The problem of predicting the effects of wear and tear on the performance of any engine is still a matter of discussion. Because the function of a gas turbine is the result of the fine-tuned cooperation of many different components, the emphasis of this paper is on the gas turbine and its driven equipment (compressor or pump) as a system, rather than on isolated components. We will discuss the effect of degradation on the package as part of a complex system (e.g., a pipeline, a reinjection station, etc.). Treating the gas turbine package as a system reveals the effects of degradation on the match of the components as well as on the match with the driven equipment. This article will contribute insights into the problem of gas turbine systent degradation. Based on some detailed studies on the mechanisms that cause engine degradation, namely, changes in blade surfaces due to erosion or fouling, and the effect on the blade aerodynamics; changes in seal geometries and clearances, and the effect on parasitic flows; and changes in the combustion system (e.g., which result in different pattern factors), the effects of degradation will be discussed. The study includes a methodology to simulate the effects of engine and driven equipment degradation. With a relatively simple set of equations that describe the engine behavior, and a number of linear deviation factors which can easily be obtained from engine maps or test data, the equipment behavior for various degrees of degradation will be studied. A second model, using a stage by stage model for the engine compressor, is used to model the compressor deterioration. The authors have avoided to present figures about the speed of degradation, because it is subject to a variety of operational and design factors that typically cannot be controlled entirely.

198 citations


Journal ArticleDOI
TL;DR: In this paper, a solar assisted heat pump water heating system, where unglazed, flat plate solar collectors acted as an evaporator for the refrigerant R-134a was designed and fabricated locally, and operated under meteorological conditions of Singapore.

177 citations


Journal ArticleDOI
TL;DR: In this paper, the authors derived a semi-empirical expression for the mixing pressure loss in the blade row, as a function of the total cooling air used, and applied it to the performance of a simple open-cycle gas turbine.
Abstract: Calculations of the performance of modern gas turbines usually include allowance for cooling air flow rate; assumptions are made for the amount of the cooling air bled from the compressor, as a fraction of the mainstream flow, but this fractional figure is often set in relatively arbitrary fashion. There are two essential effects of turbine blade cooling: (i) the reduction of the gas stagnation temperature at exit from the combustion chamber (entry to the first nozzle row) to a lower stagnation temperature at entry to the first rotor and (ii) a pressure loss resulting from mixing the cooling air with the mainstream, Similar effects occur in the following cooled blade rows. The paper reviews established methods for determining the amount of cooling air required and semi-empirical relations, for film cooled blading with thermal barrier coatings, are derived. Similarly, the pressure losses related to elements of cooling air leaving at various points round the blade surface are integrated over the whole blade. This gives another semi-empirical expression, this time for the complete mixing pressure loss in the blade row, as a function of the total cooling air used. These two relationships are then used in comprehensive calculations of the performance of a simple open-cycle gas turbine, for varying combustion temperature and pressure ratio. These calculations suggest that for maximum plant efficiency there may be a limiting combustion temperature (below that which would be set by stoichiometric combustion). For a given combustion temperature, the optimum pressure ratio is reduced by the effect of cooling air.

155 citations


Journal ArticleDOI
TL;DR: In this paper, an analysis was conducted for a multi-type inverter air conditioner with a linear electronic valve as the expansion device and a variable speed compressor, and the system performance was analyzed with variations of operating frequency of the compressor, cooling load imposed on the system and cooling load fraction (i.e. load ratio) between rooms in which is installed an evaporator.

128 citations


Journal ArticleDOI
TL;DR: In this paper, the authors describe models for the transient analysis of heavy duty gas turbines, and present dynamic simulation results of a modern gas turbine for electric power generation, including the effect of movable vanes, which govern the operating behavior of a whole engine.
Abstract: This paper describes models for the transient analysis of heavy duty gas turbines, and presents dynamic simulation results of a modern gas turbine for electric power generation. Basic governing equations have been derived from integral forms of unsteady conservation equations. Mathematical models of each component are described with the aid of unsteady one-dimensional governing equations and steady-state component characteristics. Special efforts have been made to predict compressor characteristics including the effect of movable vanes, which govern the operating behavior of a whole engine. The derived equation sets are solved numerically by a fully implicit method. A controller model that maintains constant rotational speed and target temperature (turbine inlet or exhaust temperature) is used to simulate practical operations. Component models, especially those of the compressor, are validated through comparison with test data, The dynamic behavior of a 150 MW class engine is simulated. The time-dependent variations of engine parameters such as power, rotational speed, fuel, temperature, and guide vane angles are compared with field data. Simulated results are fairly close to the operation data.

120 citations


Journal ArticleDOI
TL;DR: In this paper, an integral type solar-assisted heat pump water heater (ISAHP) was designed to operate at an evaporating temperature lower than the ambient temperature and a matched condition (near saturated vapor compression cycle and compressor exhaust temperature).

118 citations


Patent
26 Nov 2001
TL;DR: In this article, the authors present a boiler with heat exchanger coils containing water and receives hot exhaust gases for vaporizing water in the coils and producing steam which is supplied to a steam turbine coupled to a generator for expanding steam produced by the boiler, and driving the generator and producing power and expanded steam.
Abstract: Retrofit equipment includes an auxiliary gas turbine unit including an auxiliary compressor for compressing ambient air to produce compressed air, a solar collector that receives the compressed air for heating the same to produce heated compressed air, and an auxiliary turbine coupled to the auxiliary compressor and to an auxiliary generator for expanding the heated compressed air and driving the auxiliary compressor and auxiliary generator thereby producing power and hot exhaust gases. When solar insolation is available, a flow control selectively supplies the hot exhaust gases from the retrofit equipment to a boiler which is part of a conventional fossil fueled power plant. The boiler has heat exchanger coils containing water and receives hot exhaust gases for vaporizing water in the coils and producing steam which is supplied to a steam turbine coupled to a generator for expanding steam produced by the boiler, and driving the generator and producing power and expanded steam. A condenser condenses the expanded steam to condensate, and a pump returns the condensate to the boiler. When solar insolation is not available. e.g., during the night, the flow control supplies the boiler with hot gases from a primary gas turbine unit which includes a primary compressor that compresses ambient air to produce compressed air, and a combustor that receives the compressed air for burning fossil fuel and heating the compressed air to produce heated compressed air that is supplied to the primary turbine.

Proceedings ArticleDOI
01 Jan 2001
TL;DR: This paper explores various low power higher order compressors such as 4-2 and 5-2 compressor units, which are building blocks for binary multipliers.
Abstract: This paper explores various low power higher order compressors such as 4-2 and 5-2 compressor units. These compressors are building blocks for binary multipliers. Various circuit architectures for 4-2 compressors are compared with respect to their delay and power consumption. The different circuits are simulated using HSPICE. A new circuit for a 5-2 compressor is then presented which is 12% faster and consumes 37% less power.

Patent
23 Jul 2001
TL;DR: In this article, a rotatable shaft, a turbine wheel, and a multi-stage compressor are used in an internal combustion engine to extract exhaust gas from the turbine to an interstage duct area between two compressor wheels.
Abstract: A turbocharger, particularly suitable for use in an internal combustion engine, recirculates exhaust gas from the turbine to an interstage duct area between two compressor wheels of a multi-stage compressor. The turbocharger includes a rotatable shaft; a turbine including a turbine wheel carried by the shaft; and a multi-stage compressor. The multi-stage compressor includes a first compressor wheel carried by the shaft, an axially extending first inlet associated with the first compressor wheel, and a radially extending first outlet associated with the compressor wheel. A second compressor wheel carried by the shaft includes an axially extending second inlet associated with the second compressor wheel, and a radially extending second outlet associated with the second compressor wheel. An interstage duct fluidly interconnects in series the first outlet associated with the first compressor wheel and a second inlet associated with the second compressor wheel. An exhaust gas recirculation duct fluidly interconnects the turbine with the interstage duct. A valve is positioned within the exhaust gas recirculation duct.

Patent
27 Sep 2001
TL;DR: In this article, a transmission header compressor and a moving picture encoder are used to synchronize a timing at which the compressor inhibits compression of transmission headers with a timing when the encoder executes intra-frame coding.
Abstract: A transmission header compressor and a moving-picture encoder each include a respective circuit for synchronizing a timing at which the compressor inhibits compression of transmission headers with a timing at which the encoder executes intra-frame coding A moving-picture transmission system including the compressor and encoder is also disclosed

Journal ArticleDOI
TL;DR: In this paper, the main geometric features of a flow component can be deduced from the thermodynamic optimization of the global performance of the largest flow system that incorporates the component, and the method illustrated in this paper is applicable to any system that runs on the basis of a limited amount of fuel (exergy) installed onboard.

Patent
26 Feb 2001
TL;DR: In this article, a compressor protection and control subsystem for a rotary compressor provides temperature pressure, miswiring and vibrational protection for the scroll machine, in conjunction with at least one timer, monitors the vibrations of the rotor and will shut down the machine when excess vibrations are sensed over a prespecified period of time.
Abstract: A compressor protection and control subsystem for a rotary compressor provides temperature pressure, mis-wiring and vibrational protection for the scroll machine. The vibrational protection comprises a vibration sensor which is integrated on the circuit board of the protection and control subsystem. The vibration sensor, in conjunction with at least one timer, monitors the vibrations of the scroll machine and will shut down the machine when excess vibrations are sensed over a prespecified period of time. The temperature system monitors operating temperature conditions the pressure system monitors operating pressures and the mis-wiring system monitors the power supplied to the compressor. Once an undesirable characteristic is identified, the operation of the scroll machine is stopped. These protection systems are integrated into a single subsystem which identifies the reason of shutting off the scroll machine in order to simplify repairs needed. The subsystem incorporates a gateway and/or a serial peripheral interface in order to communicate with a central operating and control system.

Journal ArticleDOI
TL;DR: In this article, fundamental and practical influence of liquid refrigerant injection on the performance of a refrigerant scroll compressor has been investigated experimentally and theoretically, and it was found that the injection basically increases the compression power and decreases the compressor efficiency.
Abstract: In this study, fundamental and practical influence of liquid refrigerant injection on the performance of a refrigerant scroll compressor has been investigated experimentally and theoretically. In the theoretical analysis, a compression model of vapor/liquid mixture is developed by taking account of heat transfer from the cylinder wall to suction, compression and injection refrigerant. An experiment has been done under the condition of keeping the oil temperature constant in order to investigate the fundamental influence of the liquid refrigerant injection on the compressor performance, and the results were compared with the theoretical ones. It was found that the injection basically increases the compression power and decreases the compressor efficiency, though the situation depends on the condition of the heat transfer to the injection refrigerant. And furthermore, the performance of the liquid refrigerant injection compressor under practical operating condition without controlling the oil temperature has been investigated. Under this condition, the compressor showed recovery and slight improvement of performance due to the decrease of the oil and cylinder temperatures by the injection. In addition, influence of the refrigerant injection on the oil viscosity and refrigerant solubility in the oil, which relate mechanical loss and reliability of the compressor, have been discussed.

Patent
09 Mar 2001
TL;DR: In this paper, a system and method for reducing temperature variation among heat dissipating components in a multi-component computer system is presented. But, the system does not consider the effect of temperature variations among components.
Abstract: System and method for reducing temperature variation among heat dissipating components in a multi-component computer system In this respect, component temperatures are controlled to remain relatively constant (approximately within 5° C) with respect to other components, while allowing for multiple fluctuating heat loads between components A refrigeration system possessing a variable speed compressor or a constant speed compressor is utilized to control the flow of refrigerant through the refrigeration system The temperature variation among components is reduced by independently metering the mass flow rate of the refrigerant flowing into each component to compensate for the amount of heat load on each component In this respect, the mass flow rate of the refrigerant entering into each of the evaporators is metered by valves located upstream from each of the evaporators In another respect, the mass flow rate is metered by the above-described valves and a main valve provided on a secondary refrigerant line

Patent
09 Oct 2001
TL;DR: In this article, a turbine airfoil section having an internal cavity and a plurality of indentations on the inner surface of the internal cavity is described, where the indentations provide enhanced heat transfer.
Abstract: A turbine airfoil section having an internal cavity and a plurality of indentations on the inner surface of the internal cavity is described. The indentations provide enhanced heat transfer for cooling the internal cavity of an airfoil thereby improving the life of the airfoil and optimizing the efficiency of the engine by minimizing the amount of compressor bleed air required. Advantageously, this cooling scheme also does not restrict the cooling flow within the internal cavity. The indentations may have varying patterns and alternative geometric configurations.

Patent
14 Sep 2001
TL;DR: An apparatus and process for supplying low pressure oxygen-enriched gas to a patient and at moderate pressure to a radial compressor, whereupon it is compressed and fed to a high pressure storage tank is described in this paper.
Abstract: An apparatus and process for supplying low pressure oxygen-enriched gas to a patient and at a moderate pressure to a radial compressor, whereupon it is compressed and fed to a high pressure storage tank. The oxygen-enriched gas is prioritized so that it is continuously supplied via a patient flow line to the patient.

Journal ArticleDOI
01 Sep 2001
TL;DR: In this article, a simple bleed system was adopted for internal flow recirculation to a high flowrate, high efficiency, pressure ratio 4.2 centrifugal compressor stage, and computational fluid dynamics calculations were performed in order to gain insight into the flow pattern in both the compressor stage and the bleed system.
Abstract: State-of-the-art centrifugal compressors for turbocharger applications are required to provide broad compressor maps, high pressure ratios and high efficiency levels. Usually these requirements are perceived as contradictory and represent challenging design targets. Various techniques for map width enhancements have been reported since the early 1980s. ABB Turbo Systems Limited has adopted a simple bleed system for internal flow recirculation to a high flowrate, high efficiency, pressure ratio 4.2 centrifugal compressor stage. After initial test runs had proved the effectiveness of the bleed system, computational fluid dynamics (CFD) calculations were performed in order to gain insight into the flow pattern in both the compressor stage and the bleed system. The simulations explain the effectiveness by comparing them with simulations without the bleed channel. Selected streamline and iso-surface plots show the effect of the bleed channel flow on the main flow through the impeller. Four more variant...

Patent
27 Mar 2001
TL;DR: In this paper, a turbocharged internal combustion engine assembly with exhaust gas recirculation (EGR) includes an air compressor driven by an exhaust turbine, an EGR line that diverts exhaust gases from an exhaust line leading from the engine to an air intake line leading to the engine from the compressor, and a combustion bypass line that conveys compressed air from the compressors to the exhaust turbine without combustion.
Abstract: A turbocharged internal combustion engine assembly with exhaust gas recirculation (EGR) includes an air compressor driven by an exhaust turbine, an EGR line that diverts exhaust gases from an exhaust line leading from the engine to an air intake line leading to the engine from the compressor, and a combustion bypass line that conveys compressed air from the compressor to the exhaust turbine without combustion. A pressure adjusting feature disposed along at least one of the air intake line and the exhaust line maintains the pressure at the turbine inlet below the pressure at the compressor outlet and above the pressure at the air inlet of the engine. Examples of suitable pressure adjusting features include a venturi placed in the air intake line at the second point, a power turbine located along the exhaust line downstream of the exhaust turbine, a split exhaust manifold feeding unequal turbine inlets, and an orifice located along the exhaust line between the EGR line and the bypass line.

Patent
18 Apr 2001
TL;DR: In this paper, an ECU sets a target temperature difference between water flowing into a water heat exchanger and refrigerant flowing out from the water heat exchange, and controls a valve opening degree of an expansion valve so that the target temperature discrepancy is obtained.
Abstract: In a heat-pump water heater, an ECU sets a target temperature difference between water flowing into a water heat exchanger and refrigerant flowing out from the water heat exchanger, and controls a valve opening degree of an expansion valve so that the target temperature difference is obtained. When a refrigerant temperature discharged from a compressor is higher than a predetermined value, the target temperature difference is increased until the refrigerant temperature discharged from the compressor becomes lower than the predetermined value. Further, when water-heating capacity is decreased due to the increase of the target temperature difference, a rotation speed of the compressor is increased.

Journal ArticleDOI
TL;DR: In this article, a Digital Particle Imaging Velocimetry (DPIV) is used in conjunction with dynamic pressure transducers to simultaneously capture transient velocity and pressure measurements in the nonstationary flow field during compressor surge.
Abstract: Compressor stall is a catastrophic breakdown of the flow in a compressor, which can lead to a loss of engine power, large pressure transients in the inlet/nacelle and engine flameout. The implementation of active or passive strategies for controlling rotating stall and surge can significantly extend the stable operating range of a compressor without substantially sacrificing performance. It is crucial to identify the dynamic changes occurring in the flow field prior to rotating stall and surge in order to successfully control these events. Generally, pressure transducer measurements are made to capture the transient response of a compressor prior to rotating stall. In this investigation, Digital Particle Imaging Velocimetry (DPIV) is used in conjunction with dynamic pressure transducers to simultaneously capture transient velocity and pressure measurements in the non-stationary flow field during compressor surge. DPIV is an instantaneous, planar measurement technique which is ideally suited for studying transient flow phenomena in high speed turbomachinery and has been used previously to successfully map the stable operating point flow field in the diffuser of a high speed centrifugal compressor. Through the acquisition of both DPIV images and transient pressure data, the time evolution of the unsteady flow during surge is revealed.

Patent
02 Jul 2001
TL;DR: In this paper, the variable speed drive is cooled by refrigerant from the refrigeration system, which permits the use of a smaller drive, and a variable speed driver is operated at, or approaching, a unity power factor.
Abstract: The compressor in a refrigeration system is controlled solely by a variable speed drive which controls the motor of the compressor by virtue of the varying of the frequency of the electricity provided to the motor. To minimize the initial cost and to minimize operating costs, the variable speed drive is cooled by refrigerant from the refrigeration system which permits the use of a smaller drive, and the variable speed drive is operated at, or approaching, a unity power factor.

Patent
05 Sep 2001
TL;DR: A gas turbine engine comprising a combustion chamber (52), a turbine section (16) and a compressor section (12) is described in this paper, where the turbine section is surrounded by the combustion chamber and the compressor section by the turbine.
Abstract: A gas turbine engine comprising a combustion chamber (52), a turbine section (16) and a compressor section (12). The turbine section (16) surrounds the combustion chamber (52) and the compressor section (12) surrounds the turbine section (16).

Patent
Frutschi Hans Ulrich1
06 Dec 2001
TL;DR: In this paper, a process for the operation of a gas turbine plant with CO 2 as working medium is described, in which in at least one combustion chamber hydrocarbons are combusted in a CO 2 atmosphere enriched with oxygen to flue gases, which largely consist of CO 2 and H 2 O and which are expanded within a turbine stage following the combustion chamber, and are then compressed in a compressor stage and also at least partially condensed in a following condenser.
Abstract: A process is described for the operation of a gas turbine plant with CO 2 as working medium, in which in at least one combustion chamber hydrocarbons are combusted in a CO 2 atmosphere enriched with oxygen to flue gases, which largely consist of CO 2 and H 2 O and which are expanded within a turbine stage following the at least one combustion chamber, and are then compressed in a compressor stage and also at least partially condensed in a following condenser, so that at least portions of the CO 2 and H 2 O are liquefied and partially drawn off together with uncondensed flue gas constituents, and so that a main portion, not drawn off, of liquid CO 2 is compressed by means of a pump unit, preheated in at least one recuperator stage, and is again supplied to the combustion chamber. The invention is distinguished in that the compressed and preheated main portion CO 2 is pre-expanded to a combustion pressure and is supplied to the combustion chamber for combustion with the main portion CO 2 .

Patent
02 Aug 2001
TL;DR: A component gas concentrator includes an air compressor, an air-tight first container containing a molecular sieve bed, the first container in fluid communication with the compressor through a first gas conduit, and an airtight second container with a gas flow controller such as PLC controls actuation of valves mounted to the gas conduits.
Abstract: A component gas concentrator includes an air compressor, an air-tight first container containing a molecular sieve bed, the first container in fluid communication with the compressor through a first gas conduit, and an air-tight second container in fluid communication with the first container through a second gas conduit A gas flow controller such as PLC controls actuation of valves mounted to the gas conduits

Journal ArticleDOI
TL;DR: In this article, the authors developed a formal framework for modeling air-cooled gas turbine cycles and dealt with basic thermodynamic issues, such as thermal mixing loss and cooling loss.
Abstract: This paper is Part I of a study concerned with developing a formal framework for modelling air-cooled gas turbine cycles and deals with basic thermodynamic issues. Such cycles involve gas mixtures with varying composition which must be modelled realistically. A possible approach is to define just two components, air and gas, the latter being the products of stoichiometric combustion of the fuel with air. If these components can be represented as ideal gases, the entropy increase due to compositional mixing, although a true exergy loss, can be ignored for the purpose of performance prediction. This provides considerable simplification. Consideration of three idealised simple cycles shows that the introduction of cooling with an associated thermal mixing loss does not necessarily result in a loss of cycle efficiency. This is no longer true when real gas properties and turbomachinery losses are included. The analysis clarifies the role of the cooling losses and shows the importance of assessing performance in the context of the complete cycle. There is a strong case for representing the cooling losses in terms of irreversible entropy production as this provides a formalised framework, clarifies the modelling difficulties and aids physical interpretation. Results are presented which show the effects on performance of varying cooling flowrates and cooling losses. A comparison between simple and reheat cycles highlights the role of the thermal mixing loss. Detailed modelling of the heat transfer and cooling losses is discussed in Part II of this paper Copyright © 2001 by ASME.

Patent
14 Sep 2001
TL;DR: In this paper, a passage fluidly couples the compressor and the interior volume of the aircraft, and a heat dissipating device, such as a heat exchanger, is positioned in the passage to extract heat energy from the supply air.
Abstract: An all electric air conditioning system for an aircraft, wherein the aircraft defines an interior volume having conditioned air at a first pressure. A compressor is provided and is operable to compress supply air to a second pressure. The compressor being operated in response to an electrical drive motor. A passage fluidly couples the compressor and the interior volume of the aircraft. A heat dissipating device, such as a heat exchanger, is positioned in the passage to extract heat energy from the supply air. This arrangement permits conditioning of air within the aircraft without using bleed air from the engines. The use of bleed air results in a significant amount of fuel burn. An optional conditioned air recovery system may be coupled to the interior volume of the fuselage to direct at least a portion of the conditioned air from the interior volume back for further conditioning and use.