Patents by Inventor Giridhari L. Agrawal
Giridhari L. Agrawal has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 11585222Abstract: A cryogenic oil-free direct drive turbogenerator for gas liquefaction plant applications is described. The pressure energy from cryogenic gas is expanded through a turbine and the power generated is converted into electricity through a directly driven generator and a power electronics arrangement. The machinery can withstand very cold temperature operation (e.g., <?425° F.) by isolating the cold turbine side from the warmer side of the machine turbine end and has a hermetically sealed design wherein the process gas is fully contained from leaking at operating pressures. A unique gas injection scheme uses seal gas segregation, thrust bearing cooling and pressure balance for thrust control which is accomplished through a pressure regulator arrangement. Also described is an algorithm for speed control and overspeed protection through the power electronics system. The rotating components of the turbogenerator are supported on foil gas bearings for oil-free operation eliminating extraneous lubrication.Type: GrantFiled: August 18, 2022Date of Patent: February 21, 2023Assignee: R&D Dynamics CorporationInventors: Muthusamy Rajendran, Charles William Buckley, Giridhari L. Agrawal, Aren Andreas Johansen
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Patent number: 11025121Abstract: An electric motor includes a stator; an annular end cap, fastened at a first end of the stator; a threaded seat that is mounted at an outward end face of the annular end cap for receiving a first gas foil thrust bearing; a shaft, inserted through the stator, through the annular end cap, and through the threaded seat; a thrust runner mounted at an end of said shaft adjacent the threaded seat; a first gas foil thrust bearing that is mounted into the threaded seat, adjacent a face of the thrust runner facing the stator; a bearing cap that has a threaded fitting by which it is attached onto the threaded seat; and a second gas foil thrust bearing that is mounted into the bearing cap adjacent to a face of the thrust runner opposite the first gas foil thrust bearing.Type: GrantFiled: May 18, 2018Date of Patent: June 1, 2021Assignee: R&D Dynamics CorporationInventors: Alexander R. Nelson, Charles W. Buckley, Giridhari L. Agrawal
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Publication number: 20180269742Abstract: An electric motor includes a stator; an annular end cap, fastened at a first end of the stator; a threaded seat that is mounted at an outward end face of the annular end cap for receiving a first gas foil thrust bearing; a shaft, inserted through the stator, through the annular end cap, and through the threaded seat; a thrust runner mounted at an end of said shaft adjacent the threaded seat; a first gas foil thrust bearing that is mounted into the threaded seat, adjacent a face of the thrust runner facing the stator; a bearing cap that has a threaded fitting by which it is attached onto the threaded seat; and a second gas foil thrust bearing that is mounted into the bearing cap adjacent to a face of the thrust runner opposite the first gas foil thrust bearing.Type: ApplicationFiled: May 18, 2018Publication date: September 20, 2018Applicant: R&D Dynamics CorporationInventors: Alexander R. Nelson, Charles W. Buckley, Giridhari L. Agrawal
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Patent number: 10006465Abstract: A high-speed, single-stage, motor-driven blower designed to move water vapor includes an axial flow compressor and a rotating assembly supported by gas foil bearings and driven by a brushless permanent magnet synchronous motor utilizing a remotely mounted variable frequency drive. The blower is immersed in a water vapor flow for operation. Accordingly, the blower comprises an outer blower housing and an inner blower housing defining an annular cavity therebetween, wherein the inner blower housing is held within the outer blower housing by seals, and contains and protects the motor components and the bearings against water damage and contamination. A cooling flow may be leaked through the inner blower housing to cool the internal operational components of the blower and to capture heat therefrom, which can be added to the water vapor flow moving through the blower.Type: GrantFiled: October 3, 2011Date of Patent: June 26, 2018Assignee: R&D Dynamics CorporationInventors: Giridhari L. Agrawal, Charles W. Buckley, Jared Knechel
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Patent number: 10008898Abstract: An electric motor stator includes an armature surrounding a longitudinal opening for receiving a shaft, with longitudinal fins protruding from an outer surface of said armature; windings are wound within the armature and protruding beyond ends of the armature; and encapsulant seals the windings to the armature, such that the encapsulant serves as an outer housing for the windings.Type: GrantFiled: July 29, 2015Date of Patent: June 26, 2018Assignee: R&D Dynamics CorporationInventors: Alexander R. Nelson, Charles W. Buckley, Giridhari L. Agrawal
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Patent number: 10008899Abstract: An electric motor includes a stator; an annular end cap, fastened at a first end of the stator; a threaded seat that is mounted at an outward end face of the annular end cap for receiving a first gas foil thrust bearing; a shaft, inserted through the stator, through the annular end cap, and through the threaded seat; a thrust runner mounted at an end of said shaft adjacent the threaded seat; a first gas foil thrust bearing that is mounted into the threaded seat, adjacent a face of the thrust runner facing the stator; a bearing cap that has a threaded fitting by which it is attached onto the threaded seat; and a second gas foil thrust bearing that is mounted into the bearing cap adjacent to a face of the thrust runner opposite the first gas foil thrust bearing.Type: GrantFiled: July 29, 2015Date of Patent: June 26, 2018Assignee: R&D Dynamics CorporationInventors: Alexander R. Nelson, Charles W. Buckley, Giridhari L. Agrawal
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Patent number: 9951784Abstract: A hermetically-sealed turbomachine, such as a motor-driven blower and a turbine driven generator, capable of reliable high-temperature operation, especially for large sized turbomachine includes a hot blower, compressor or turbine end of the turbomachine that is separated from the cooler electric motor, generator or alternator end of the turbomachine by a compliant mechanical coupling and a thermal choke assembly. The turbomachine housing is also hermetically sealed, providing control over the process gas within the machine housing, and permitting an internal cooling method within the turbomachine, whereby a small amount of process gas itself is used within the turbomachine for providing cooling of the rotating shafts, the axial fan, radial fan, or turbine impeller, the bearings and the electric motor, generator or alternator disposed within the turbomachine housing. The cooling method can be aided by a heat exchanger operatively communicating with the turbomachine.Type: GrantFiled: July 27, 2011Date of Patent: April 24, 2018Assignee: R&D Dynamics CorporationInventors: Giridhari L. Agrawal, Charles W. Buckley, Muthusamy Rajendran
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Publication number: 20160365767Abstract: An electric motor stator includes an armature surrounding a longitudinal opening for receiving a shaft, with longitudinal fins protruding from an outer surface of said armature; windings are wound within the armature and protruding beyond ends of the armature; and encapsulant seals the windings to the armature, such that the encapsulant serves as an outer housing for the windings.Type: ApplicationFiled: July 29, 2015Publication date: December 15, 2016Applicant: R&D Dynamics CorporationInventors: Alexander R. Nelson, Charles W. Buckley, Giridhari L. Agrawal
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Publication number: 20160365770Abstract: An electric motor includes a stator; an annular end cap, fastened at a first end of the stator; a threaded seat that is mounted at an outward end face of the annular end cap for receiving a first gas foil thrust bearing; a shaft, inserted through the stator, through the annular end cap, and through the threaded seat; a thrust runner mounted at an end of said shaft adjacent the threaded seat; a first gas foil thrust bearing that is mounted into the threaded seat, adjacent a face of the thrust runner facing the stator; a bearing cap that has a threaded fitting by which it is attached onto the threaded seat; and a second gas foil thrust bearing that is mounted into the bearing cap adjacent to a face of the thrust runner opposite the first gas foil thrust bearing.Type: ApplicationFiled: July 29, 2015Publication date: December 15, 2016Applicant: R&D DYNAMICS CORPORATIONInventors: Alexander R. Nelson, Charles W. Buckley, Giridhari L. Agrawal
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Patent number: 9476428Abstract: A turbine-driven alternator (i.e., a turbomachine) suitable for generating electrical power from process gas waste energy. In particular suitable for very high density process gases such as super critical CO2, R134a, R245fa, etc. The turboalternator comprises two separate machines, specifically, a turbine device and an alternator device operatively connected together by a coupling shaft. The rotating shaft assemblies for each machines on the turbine side and the alternator side are supported by hydrodynamic foil gas bearings. The foil gas bearings use process gas at the turbine side, enabling high-pressure operation (˜3000 psia) and thrust load balancing. At the alternator side, cooling fluid is used in the foil gas bearings, enabling high-speed (˜40,000 rpm), low-windage, oil-free operation with closed-loop shaft cooling.Type: GrantFiled: May 31, 2012Date of Patent: October 25, 2016Assignee: R & D Dynamics CorporationInventors: Giridhari L. Agrawal, Charles W. Buckley, Ali Shakil, Andrew Hamilton Coward
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Publication number: 20140084588Abstract: A turbine-driven generator (i.e., a turbomachine) is provided for extracting energy and generating electrical power from a process gas. A turbine impeller mounted on a rotating shaft is rotatably disposed within a turbine housing for processing process gas flowing between an inlet and an outlet of the turbine. The rotating shaft of the turbine is coupled to a high-speed pinion of a reduction gear assembly to transfer torque from the turbine, via the gear assembly, to a generating device. Upon operation of the turbine impeller, rotation of the turbine rotating shaft, often at high speeds, is transferred to the high-speed pinion, which transfers torque to a low-speed gear of the gear assembly in engagement with the pinion. Rotation of the low-speed gear in turn causes a rotating assembly of the generating device to rotate, often at much lower speeds, which generates power that can be directed to an energy grid.Type: ApplicationFiled: September 23, 2013Publication date: March 27, 2014Inventors: Giridhari L. Agrawal, Charles W. Buckley
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Publication number: 20130129488Abstract: A high-speed blower designed to move and circulate dry process gas includes an axial or mixed-flow compressor driven by a brushless permanent magnet synchronous motor utilizing a remotely mounted variable frequency drive. The blower uses foil gas bearings which enable high-speed, low-power loss, and oil-free operation. The blower comprises an outer blower housing and an inner blower housing defining an annular cavity therebetween. A cooling flow of process gas may be leaked through the inner blower housing to cool the internal operational components of the blower, including the motor and the bearings, and to capture heat therefrom, which can be added to the process gas flow moving through the blower. Diffuser vanes and flow-straightening vanes are provided on the outer surface of the inner blower housing to improve the fluid dynamics of the process gas flow through the blower and heat transfer from the inner blower housing.Type: ApplicationFiled: November 16, 2012Publication date: May 23, 2013Inventors: Giridhari L. Agrawal, Charles W. Buckley, Alexander R. Nelson
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Publication number: 20120306206Abstract: A turbine-driven alternator (i.e., a turbomachine) suitable for generating electrical power from process gas waste energy. In particular suitable for very high density process gases such as super critical CO2, R134a, R245fa, etc. The turboalternator comprises two separate machines, specifically, a turbine device and an alternator device operatively connected together by a coupling shaft. The rotating shaft assemblies for each machines on the turbine side and the alternator side are supported by hydrodynamic foil gas bearings. The foil gas bearings use process gas at the turbine side, enabling high-pressure operation (˜3000 psia) and thrust load balancing. At the alternator side, cooling fluid is used in the foil gas bearings, enabling high-speed (˜40,000 rpm), low-windage, oil-free operation with closed-loop shaft cooling.Type: ApplicationFiled: May 31, 2012Publication date: December 6, 2012Applicant: R&D Dynamics CorporationInventors: Giridhari L. Agrawal, Charles W. Buckley, Ali Shakil, Andrew Hamilton Coward
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Patent number: 8242721Abstract: This invention provides an advanced position and velocity estimation scheme used in a position-sensorless control system for synchronous operation of an electric motor. The system includes an electric motor having a stator and a rotor; an inverter for powering the electric motor; and a controller for controlling the inverter. The controller utilizes a control system comprising a rotor angle and angular velocity estimation block; an estimated angle error detector block; a field-weakening block; and a torque-to-current converter block, all of which operate to generate control commands for operation of the motor.Type: GrantFiled: October 30, 2009Date of Patent: August 14, 2012Assignee: R&D Dynamics CorporationInventors: Jeong Hyeck Kwon, Edward A. Clark, Giridhari L. Agrawal
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Patent number: 8215928Abstract: This invention provides a blower design capable of high temperature operation due to use of a self-sustaining cooling scheme through a sealed motor housing in which a cooling circuit can be created, and the use of a thermal barrier across which a temperature gradient may be formed. The thermal barrier may be formed by a thermal choke plate assembly positioned between a hot side and a cold side of the blower to dissipate heat conducted from the hot side. Alternatively, the thermal barrier may be formed by an internal fan ring provided with the blower's rotating assembly to dissipate heat conducted from the blower's impeller. The thermal choke plate assembly and the fan ring may further be used in combination to block heat transfer by all modes between a hot side and a cold side of the blower.Type: GrantFiled: October 2, 2008Date of Patent: July 10, 2012Assignee: R&D Dynamics CorporationInventors: Giridhari L. Agrawal, Charles William Buckley, Ali Shakil
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Publication number: 20120082575Abstract: A high-speed, single-stage, motor-driven blower designed to move water vapor includes an axial flow compressor and a rotating assembly supported by gas foil bearings and driven by a brushless permanent magnet synchronous motor utilizing a remotely mounted variable frequency drive. The blower is immersed in a water vapor flow for operation. Accordingly, the blower comprises an outer blower housing and an inner blower housing defining an annular cavity therebetween, wherein the inner blower housing is held within the outer blower housing by seals, and contains and protects the motor components and the bearings against water damage and contamination. A cooling flow may be leaked through the inner blower housing to cool the internal operational components of the blower and to capture heat therefrom, which can be added to the water vapor flow moving through the blower.Type: ApplicationFiled: October 3, 2011Publication date: April 5, 2012Inventors: Giridhari L. Agrawal, Charles W. Buckley, Jared Knechel
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Publication number: 20120027567Abstract: The present invention provides a hermetically sealed turbomachine, such as a motor-driven blower and a turbine driven generator, capable of reliable high-temperature operation, especially for large sized turbomachines. The hot blower, compressor or turbine end of the turbomachine is separated from the cooler electric motor, generator or alternator end of the turbomachine by a compliant mechanical coupling and a thermal choke assembly, providing reliable high-temperature operation. The turbomachine housing is also hermetically sealed, providing control over the process gas within the machine housing, and permitting an internal cooling method within the turbomachine, whereby a small amount of process gas itself is used within the turbomachine for providing cooling of the rotating shafts, the axial fan, radial fan, or turbine impeller, the bearings and the electric motor, generator or alternator disposed within the turbomachine housing.Type: ApplicationFiled: July 27, 2011Publication date: February 2, 2012Applicant: R&D Dynamics CorporationInventors: Giridhari L. Agrawal, Charles W. Buckley, Muthusamy Rajendran
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Patent number: 8029194Abstract: A hydrodynamic fluid film bearing assembly has a stationary retaining member defining a central opening and having an inner surface lined by a foil assembly comprised of a plurality of foil subassemblies. Each foil subassembly comprises a first compliant foil, a second compliant foil, and a spring foil, and subtending a rotational segment, less than all, of the inner surface of the retaining member. The complaint foils and the spring foil of each foil subassembly are held within the retaining member in such a way that sliding travel of one compliant foil along the inner surface of the opening is in the opposite rotational direction of sliding travel of the other compliant foil and the spring foil. The foil subassemblies may be restrained from undesired movement during operation by a retention tab extending from the foil subassembly which engages a channel and recess feature formed in the retaining member.Type: GrantFiled: June 17, 2008Date of Patent: October 4, 2011Assignee: R&D Dynamics CorporationInventors: Giridhari L. Agrawal, Thomas A. Accomazzo, Michael Brophy
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Patent number: 7948105Abstract: This invention provides a small, high efficiency, oil-free turbine-driven alternator (i.e. turboalternator) suitable for conversion of stored energy in a process gas to electrical power, facilitating recapture of energy during operation that would otherwise be wasted. The turboalternator includes a turbine and a generating device operatively connected together by a rotating shaft capable of rotating at high speeds. The rotating shaft is supported by foil gas bearings.Type: GrantFiled: January 31, 2008Date of Patent: May 24, 2011Assignee: R&D Dynamics CorporationInventors: Giridhari L. Agrawal, Charles William Buckley
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Publication number: 20100313582Abstract: A high efficiency R744 air conditioning and refrigeration system and cycle comprises a vapor compressor and two independent ejectors operatively connected to high and low-pressure sides of the compressor, respectively. The two ejectors reduce the overall pressure ratio of the mechanical vapor compressor resulting in dramatically increased thermodynamic cycle efficiency. As one example of its potential applications for residential, commercial or industrial uses, a 150 ton capacity of a water-cooled chiller designed in accordance with the present invention is predicted to provide the power consumption as low as 0.47 kW/ton, when operated in accordance with the cooling methods of the present invention, which corresponds to 7.47 of Coefficient of Performance (COP).Type: ApplicationFiled: June 10, 2010Publication date: December 16, 2010Inventors: JongSik Oh, Giridhari L. Agrawal, Charles William Buckley