Showing papers on "Gas compressor published in 2009"

Two-stage heat pump system with vapor-injected scroll compressor using R410A as a refrigerant

Abstract: Refrigerant vapor-injection technique has been well justified to improve the performance of systems in refrigeration applications. However, it has not received much attention for air conditioning applications, particularly for air conditioning in hot climates and for heat pumping in cold climates. In this study, the performance of an 11 kW R410A heat pump system with a two-stage vapor-injected scroll compressor was experimentally investigated. The vapor-injected scroll compressor was tested with the cycle options of both flash tank and internal heat exchanger configurations. A cooling capacity gain of around 14% with 4% COP improvement at the ambient temperature of 46.1 °C and about 30% heating capacity improvement with 20% COP gain at the ambient temperature of −17.8 °C were found for the vapor-injected R410A heat pump system as compared to the conventional system which has the same compressor displacement volume.

Megaspeed Drive Systems: Pushing Beyond 1 Million r/min

Abstract: The latest research in mesoscale drive systems is targeting rotational speeds toward 1 million r/min for a power range of 1-1 kW. Emerging applications for megaspeed drives (MegaNdrives) are to be found in future turbo compressor systems for fuel cells and heat pumps, generators/starters for portable nanoscale gas turbines, printed circuit board drilling and machining spindles, and electric power generation from pressurized gas flow. The selection of the machine type and the challenges involved in designing a machine for megaspeed operation such as the winding concepts, a mechanical rotor design capable of 1 000 000 r/min, the selection of magnetic materials for the stator, and the optimization concerning high-frequency losses and torque density are presented. Furthermore, a review of the advantageous inverter topologies, taking into account the extremely low stator inductance and possible high-speed bearing types such as ball bearings, air bearings, foil bearings, and magnetic bearings, are given. Finally, prototypes and experimental results originating from MegaNdrive research at Swiss Federal Institute of Technology Zurich are discussed and extreme temperature operation and power microelectricalmechanical system are identified as targets for future research.

Method and apparatus for cooling

Abstract: A method of calculating net sensible cooling capacity of a cooling unit (10) includes measuring a discharge pressure from of fluid from a compressor (30) and a suction pressure from an evaporator (44), calculating a condensing temperature of fluid flowing from the compressor and an evaporating temperature of fluid flowing from the evaporator, calculating a mass flow rate of fluid flowing from the compressor, calculating enthalpy of fluid flowing from the compressor, of fluid flowing from the thermal expansion valve (48), and of fluid flowing from the evaporator, calculating a mass flow rate of fluid flowing through the hot gas bypass valve (64), and calculating net sensible cooling capacity. Embodiments of cooling units and other methods are further disclosed.

Low emission power generation and hydrocarbon recovery systems and methods

Abstract: Methods and systems for low emission power generation in hydrocarbon recovery processes are provided. One system includes integrated pressure maintenance and miscible flood systems with low emission power generation. An alternative system provides for low emission power generation, carbon sequestration, enhanced oil recovery (EOR), or carbon dioxide sales using a hot gas expander and external combustor. Another alternative system provides for low emission power generation using a gas power turbine to compress air in the inlet compressor and generate power using hot carbon dioxide laden gas in the expander. Other efficiencies may be gained by incorporating heat cross-exchange, a desalination plant, co-generation, and other features.

Co2 recovery apparatus and co2 recovery method

Abstract: A CO2 recovery apparatus according to a first embodiment of the present invention includes: a CO2 absorber that brings flue gas containing CO2 into contact with CO2 absorbing liquid to reduce CO2 in the flue gas; a regenerator that reduces CO2 in CO2 absorbing liquid (rich solvent) that has absorbed the CO2 in the CO2 absorber to regenerate the CO2 absorbing liquid, so that the regenerated absorbing liquid (lean solvent), having CO2 reduced in the regenerator, is reused in the CO2 absorber; a first compressor to a fourth compressor that compress the CO2 gas released from the regenerator; and an O2 reducing apparatus arranged between the second compressor and a second cooler to reduce O2 in the CO2 gas.

Experimental performance of a compliant scroll expander for an organic Rankine cycle

Abstract: A small-scale scroll expander was developed and tested. The expander was based on a compliant scroll compressor having a displacement of ∼6.8 cm3. A test loop was also developed for determining expander performance parameters. The loop employed a compressor to pressurize the working fluid up to 2758 kPa and a heat exchanger to create the expander inlet conditions that would characterize an operating power cycle. The expander was tested with R134a as the working fluid. For power output measurements, a dynamometer was used where torque and rotational rate were measured. An important feature in adapting a scroll compressor to expander duty was the lubrication of the scroll wraps during operation and the lubrication required by the journal bearings within the expander housing. The approach used in this study was to dissolve a compatible oil into the circulating working fluid to lubricate the wraps, while a pump was employed to deliver pressurized oil to the bearings. The pressurized oil supply was als...

Thermodynamic analysis of different two-stage transcritical carbon dioxide cycles

Abstract: The aim of this paper is the thermodynamic evaluation and optimisation of different two-stage transcritical carbon dioxide cycles. Five different cycles are studied: basic single-stage cycle, single-throttling with two-stage compression cycle, split cycle, phase separation cycle and single-stage cycle coupled with a gas cooling circuit. Each basic cycle is analysed for the effect of internal heat transfer between different streams of refrigerants. In the case of two-stage compression, intermediate cooling between the compressor stages is present. An analysis on the Plank cycle for intermediate pressure higher than critical one is performed. Each cycle is optimised with regards to energy performance, calculating the optimal values of both the upper and the intermediate pressures. In the case of split cycle, the ratio of the mass flow rate in the main stream to the one in the auxiliary stream is also optimised.

Adiabatic compressed air energy storage system with liquid thermal energy storage

Abstract: An adiabatic compressed air energy storage (ACAES) system (10) includes a compressor system (16), an air storage unit (20), and a turbine system (18). The ACAES system further includes a thermal energy storage (TES) system (40) that includes a container (44), a plurality of heat exchangers (54, 56), a liquid TES medium conduit system (58) fluidly coupling the container to the plurality of heat exchangers (54, 56), and a liquid TES medium stored within the container (46). The TES system also includes a plurality of pumps (60, 62) coupled to the liquid TES medium conduit system and configured to transport the liquid TES medium (46) between the plurality of heat exchangers (54, 56) and the container (44), and a thermal separation system (48) positioned within the container (44) configured to thermally isolate a first portion of the liquid TES medium at a lower temperature (52) from a second portion of the liquid TES medium at a higher temperature (850).

Reversed-flow core for a turbofan with a fan drive gear system

Abstract: A gas turbine engine comprises a fan drive gear system, a low spool connected to the fan drive gear system, and a high spool disposed aft of the low spool. The low spool comprises a rearward-flow low pressure compressor disposed aft of the fan drive gear system, and a forward-flow low pressure turbine disposed aft of the low pressure compressor. The high spool comprises a forward-flow high pressure turbine disposed aft of the low pressure turbine, a combustor disposed aft of the high pressure turbine, and a forward-flow high pressure compressor disposed aft of the combustor.

A model-driven multivariable controller for vapor compression refrigeration systems

Abstract: A model-driven controller for vapor compression refrigeration systems is presented herein. Mathematical sub-models were developed for each of the system components: heat exchangers (condenser and evaporator), variable-speed compressor and variable-orifice electric expansion device. The overall system simulation model was used to design a MIMO controller based on the linear-quadratic Gaussian method using a state observer of the Kalman filter type. A purpose-built testing apparatus comprised of a variable-speed compressor and a pulse-width modulated expansion valve was used to collect data for the system identification and model validation exercises. It was found that the model reproduces the experimental trends of the working pressures in conditions far from the operation point (±30%) with a maximum deviation of ±5%. Additional experiments were also performed to verify the ability of the controller of tracking reference changes and rejecting thermal load disturbances as high as 15%.

High capacity chiller compressor

Abstract: A high efficiency, low maintenance single stage or multi-stage centrifugal compressor assembly for large cooling installations. The assembly is highly efficient by virtue of a variable frequency drive (VFD) that drives a permanent magnet motor and matches compressor speed with compressor load, a direct drive impeller that eliminates gearing losses, and magnetic bearings that reduce frictional losses. The back-emf produced by the motor provides an intermediate power source for the magnetic bearings in the event of a loss of electrical power. A cooling system provides direct cooling of the rotor with gas refrigerant, and cooling of the stator with liquid refrigerant. Modular construction allows the compressor to be retrofit with upgrades. An inlet guide vane system operates without need for oil lubrication. The use of light metal castings and elimination of gearing reduces the weight to one-third or less of comparably powered conventional units.

A study on performance of solid oxide fuel cell‐organic Rankine cycle combined system

Abstract: This study presents an energetic performance analysis for a combined power generation system consisting of a solid oxide fuel cell (SOFC) and an organic Rankine cycle (ORC). In order to simulate the SOFC–ORC combined system under steady-state conditions, a mathematical model is developed. The developed model is used to determine the potential effects caused by the changes of the design parameters on the energetic performance of the combined system. As design parameters, turbine inlet pressure, condenser temperature, fuel utilization, current density, compressor pressure ratio, and cell operating temperature are taken into account. In this regard, the electrical power and First Law efficiency are estimated by parametrical analysis and discussed comprehensively. Results of these analyses show that the efficiency is increased about 14–25% by recovering SOFC waste heat through ORC based on investigated design parameter conditions. Copyright © 2008 John Wiley & Sons, Ltd.

Performance analysis of open cycle gas turbines

Abstract: In this study, the performance of ideal open cycle gas turbine system was examined based on its thermodynamic analysis. The effects of some parameters, such as compressor inlet temperature (CIT), pressure ratio (PR) and the turbine inlet temperature (TIT), on the performance parameters of open cycle gas turbine were discussed. The turbine net power output, the thermal efficiency and the fuel consumption of the turbine were taken as the performance parameters. The values of these parameters were calculated using some basic cycle equations and variables values of thermodynamic properties. Other variables such as lower heating value, combustion efficiency and isentropic efficiencies of compressor and turbine were assumed to be constant. The result showed that the net power output and the thermal efficiency increased by a decrease in the CIT and increase in the TIT and PR values. If it is aimed to have a high net power output and the thermal efficiency for the turbine, the CIT should be chosen as low as possible and the TIT should be chosen as high as possible. Copyright © 2008 John Wiley & Sons, Ltd.

Interstage exhaust gas recirculation system for a dual turbocharged engine having a turbogenerator system

Abstract: An internal combustion engine defined as having an engine block for internal combustion, a high-pressure turbocharger for delivering pressurized intake air to the engine block, a low-pressure turbocharger for delivering pressurized intake air to the high-pressure turbocharger, a turbogenerator for recovering heat energy from the exhaust gas downstream of the low-pressure turbocharger to generate electricity, and an exhaust gas recirculation (EGR) system comprising an EGR-pump drawing exhaust gas from an EGR inlet located between the low-pressure and high-pressure turbocharger turbines, wherein the EGR-pump controllably delivers exhaust gas to an EGR mixer in the pressurized intake air stream at a location between the low-pressure and high-pressure turbocharger compressors. An electronic control unit (ECU) is adapted to command the EGR-pump to deliver a desired EGR flow-rate to the engine block based on look-up tables and either open-loop and/or closed-loop control algorithms.

Theoretical study of a novel refrigeration compressor – Part I: Design of the revolving vane (RV) compressor and its frictional losses

Abstract: This paper presents a new rotary type compressor, named ‘Revolving Vane (RV) compressor’, in which frictional losses are effectively reduced through the radical use of a rotating cylinder. The friction at various contact regions are formulated and analyzed, after which a parametric study is conducted to reveal configurations of the compressor that achieves high mechanical efficiencies. Inadvertently, the rotating cylinder is also found to enhance the smoothness of the compressor's operation by reducing its torque fluctuations. Besides good mechanical performance, the RV compressor is also found to possess a high volumetric efficiency, as shown in Part III of this paper series ( Teh and Ooi, in press ). In further consideration of the small number of parts and simple geometries of its components, it is believed that the RV compressor is well suited and can be readily adopted for refrigeration and air-conditioning applications.

Centrifugal compressor assembly and method

Abstract: A centrifugal compressor assembly for compressing refrigerant in a 250-ton capacity or larger chiller system comprising a motor, preferably a compact, high energy density motor or permanent magnet motor, for driving a shaft at a range of sustained operating speeds under the control of a variable speed drive Another embodiment of the centrifugal compressor assembly comprises a mixed flow impeller and a vaneless diffuser sized such that a final stage compressor operates with an optimal specific speed range for targeted combinations of head and capacity, while a non-final stage compressor operates above the optimum specific speed of the final stage compressor Another embodiment of the centrifugal compressor assembly comprises an integrated inlet flow conditioning assembly comprising a flow conditioning nose, a plurality of inlet guide vanes and a flow conditioning body that positions inlet guide vanes to condition flow of refrigerant into an impeller to achieve a target approximately constant angle swirl distribution with minimal guide vane turning

Gas turbine engine with an air cooled bearing

Abstract: A small gas turbine engine with a compressor, a combustor, and a turbine located downstream of the combustor. The compressor and turbine are supported on a rotary shaft, and a main bearing is support on the rotary shaft, the main bearing being located in a hot zone of the combustor. The main bearing includes cooling air passages within the races to provide cooling for the bearing. A cooling air is diverted from the compressor and passed through the bearing cooling passages for cooling the bearing, and then the cooling air is directed into the combustor. The cooling air is also passed through a guide nozzle before being passed through the bearing to cool both the guide nozzle and the bearing. A swirl cup injector is sued to deliver the compressed air from the compressor and the cooling air from the bearing into the combustor, the swirl cup injector also acting to draw the cooling air through the bearing.

Multicycle power generation thermodynamic system

Abstract: The invention relates to a multicycle power generation thermodynamic system. A first cycle is an improved Rankine cycle. A low-boiling medium is used as a cold source for condensing water vapour which accomplishes work doing into water, and the source of cold energy of the low-boiling medium is that the medium does work in a second cycle expansion unit to generate power and reduce temperature. The second cycle comprises: gasification evaporation, expansion work doing and temperature reduction, driving an electric generator to generate power; and after doing work, vapour is directly turned into liquid or is turned into liquid by a compressor from the vapour state, or achieves the vapour state with minimum value of compression work; the vapour is pressurized to enter an evaporator of the second cycle, the absorbed vapour is condensed, the latent heat is vaporized, and finally the vapour enters a second medium expansion machine to do work. The water vapour in the Rankine cycle condenser, which accomplishes work doing, transfers the latent heat to a second medium and then is condensed into water. When the second cycle can not completely convert the latent heat of the water vapour which accomplishes work doing into power, a third medium is used for a third cycle; the principle thereof is identical with the second cycle, but the third medium is a substance with lower boiling point. The invention can increase the thermal efficiency of a condensing type or an extracting-and-condensing style thermal power generation system, namely the Rankine cycle.

Performance evaluation of a two-stage CO2 cycle with gas injection in the cooling mode operation

Abstract: The cooling performance and reliability of a transcritical CO2 cycle can be significantly improved by using a multi-stage compressor with gas injection because the CO2 cycle has a large pressure difference across a compressor. The objective of this study is to investigate the performance and operating characteristics of a two-stage CO2 cycle with gas injection. In this study, the performances of a two-stage CO2 cycle with gas injection (called as “two-stage gas injection cycle”) were measured as the amount of refrigerant charge, first- and second-stage compressor frequencies, and first- and second-stage EEV openings were varied in the cooling mode operation. The cooling COP of the two-stage gas injection cycle was maximally enhanced by 16.5% over that of the two-stage non-injection cycle in the experiments. In addition, when the first- and second-stage EEV openings were increased, the compression ratio decreased and this in turn, improved the cooling COP of the two-stage gas injection cycle. However, when the first-stage EEV opening was increased, the mass flow rate through the evaporator decreased, and this in turn, decreased the cooling capacity of the two-stage gas injection cycle. Therefore, in the two-stage gas injection cycle, an optimum control of both EEV openings is required.