Gas compressor

About: Gas compressor is a research topic. Over the lifetime, 91817 publications have been published within this topic receiving 552209 citations.

Spike and Modal Stall Inception in an Advanced Turbocharger Centrifugal Compressor

Abstract: In turbocharger applications bleed air near the impeller exit is often used for secondary flow systems to seal bearing compartments and to balance the thrust load on the bearings. There is experimental evidence that the performance and operability of highly loaded centrifugal compressor designs can be sensitive to the amount of bleed air. To investigate the underlying mechanisms and to assess the impact of bleed air on the compressor dynamic behavior, a research program was carried out on a pre-production, 5.0 pressure ratio, high-speed centrifugal compressor stage of advanced design. The investigations showed that bleed air can significantly reduce the stable flow range. Compressor rig experiments, using an array of unsteady pressure sensors and a bleed valve to simulate a typical turbocharger environment, suggest that the path into compression system instability is altered by the bleed flow. Without bleed flow, the pre-stall behavior is dominated by short wavelength disturbances, or so called ‘spikes’, in the vaneless space between the impeller and the vaned diffuser. Introducing bleed flow at impeller exit reduces endwall blockage in the vaneless space and destabilizes the highly-loaded vaned diffuser. The impact is a 50% reduction in stable operating range. The altered diffuser characteristic reduces the compression system damping responsible for long wavelength, modal pre-stall behavior. A four-lobed backward traveling rotating stall wave is experimentally measured, in agreement with calculations obtained from a previously developed dynamic compressor model. In addition, a self-contained, endwall blockage control strategy was employed, successfully recovering 75% of the loss in surge-margin due to bleed flow and yielding a 1 point increase in adiabiatic compressor efficiency.Copyright © 2007 by ASME

Control for refrigeration compressors

Abstract: A device for controlling a single variable capacity compressor, or multiple variable capacity compressors in either parallel flow or series flow chilling systems, senses temperature and load conditions and uses feedback in conjunction with synchronously and asynchronously timed logic circuitry to automatically control loading, unloading and sequencing of the compressor or compressors in the system in selected increments, thereby yielding a significant reduction in energy consumption as well as increased precision in maintaining a desired chill temperature. Additional circuitry provides for remote manual control as well as safety shut-off and failure indication. Alternative embodiments using solid state logic, including a microprocessor embodiment, are also disclosed.

Power Plant and Control Method

Abstract: Ambient air is compressed into a compressed ambient gas flow (26) with a main air compressor (12). The compressed ambient gas flow (26) having a compressed ambient gas flow rate is delivered to a turbine combustor (32) and mixed with a fuel stream (28) having a fuel stream flow rate and a portion of a recirculated gas flow (50) to form a combustible mixture. The combustible mixture is burned and forms the recirculated gas flow (50) that drives a turbine (34). The recirculated gas flow (50) is recirculated from the turbine (34) to the turbine compressor (30) using a recirculation loop (52). At least one emission level is measured by a first emission sensor (53) in the recirculated gas flow (50) and a first control signal is generated. The fuel stream flow rate is adjusted based on the at least a first control signal to achieve substantially stoichiometric combustion.

Effects of flash tank vapor injection on the heating performance of an inverter-driven heat pump for cold regions

Abstract: A heat pump has received much attention as substitute for the conventional boiler or heating coil because of its high efficiency. For the wide application of the heat pump, the most important design factor is the performance degradation upon its installation in tropical and cold regions. In this study, the effects of flash tank vapor injection on the heating performance of a two-stage heat pump with an inverter-driven twin rotary compressor were measured and analyzed for compressor frequency ranging from 50 to 100 Hz at ambient temperatures of −15, −5, and 5 °C. The COP and heating capacity of the injection cycle were enhanced by 10% and 25%, respectively, at the ambient temperature of −15 °C. The total mass flow rate of the injection cycle was 30–38% higher than that of the non-injection cycle.

Systems and methods of reducing NOx emissions in gas turbine systems and internal combustion engines

Abstract: A gas turbine systems of reducing NO X emissions and enhancing operability comprises a compressor; a combustor disposed downstream of and in fluid communication with the compressor; a turbine assembly disposed down stream of and in fluid communication with the combustor; an oxygen-enriched gas source disposed in selective fluid communication with the compressor, the combustor, or a combination of the foregoing, wherein the oxygen-enriched gas source is a pressure swing absorption system, an electrolyzer, or a membrane reactor.