Some embodiments of a generator system can be used with the working fluid in a Rankine cycle. For example, the generator system can be used in a Rankine cycle to recover heat from one of a number of commercial applications and to convert that heat energy into electrical energy. In particular embodiments, the generator system may include a turbine generator apparatus to generate electrical energy and a liquid separator arranged upstream of the turbine generator apparatus.

Recovering heat energy

An apparatus includes an electric generator having a stator and a rotor. A first turbine wheel is coupled to a first end of the rotor to rotate at the same speed as the rotor. A second turbine wheel is coupled to a second end of the rotor opposite the first end, and configured to rotate at the same speed as the rotor. The first and second turbine wheels may rotate in response to expansion of a working fluid flowing from an inlet side to an outlet side of the turbine wheels.

Generating energy from fluid expansion

Thanks to the unique advantages such as long life cycles, high power density, minimal environmental impact, and high power quality such as fast response and voltage stability, the flywheel/kinetic energy storage system (FESS) is gaining attention recently. There is noticeable progress made in FESS, especially in utility, large-scale deployment for the electrical grid, and renewable energy applications. This paper gives a review of the recent developments in FESS technologies. Due to the highly interdisciplinary nature of FESSs, we survey different design approaches, choices of subsystems, and the effects on performance, cost, and applications. This review focuses on the state of the art of FESS technologies, especially for those who have been commissioned or prototyped. We also highlighted the opportunities and potential directions for the future development of FESS technologies.

A review of flywheel energy storage systems: state of the art and opportunities.

Active magnetic bearing-supported rotor with misaligned cageless backup bearings: A dropdown event simulation model

Some embodiments of a fluid expansion system can be used with the working fluid in a Rankine cycle. For example, the fluid expansion system can be used in a Rankine cycle to recover heat from one of a number of commercial applications and to convert that heat energy into electrical energy. In particular embodiments, the fluid expansion system may include a turbine generator apparatus to generate electrical energy and a liquid separator arranged upstream of the turbine generator apparatus.

Fluid flow in a fluid expansion system

A cryogenic gas expander system that incorporates a high-performance, high-speed permanent magnet, direct-drive generator and low loss magnetic bearings is described. Flow loop testing to 30,000 rpm was completed at the system manufacturer's facility in January 2005, and field installation is scheduled for October 2005. As part of the system testing, the rotor was dropped onto the backup bearings multiple times at an intermediate speed and at 30,000 rpm. Orbit and time-history data from a full speed drop and spin down are presented and discussed in detail. A transient, nonlinear rotordynamic analysis simulation model was developed for the machine to provide insight into the dynamic behavior. The model includes the dead band clearance, the flexible backup bearing support, and hard stop. Model predictions are discussed relative to the test data.

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Test Results and Analytical Predictions for Rotor Drop Testing of an Active Magnetic Bearing Expander/Generator

A recent trend in designing naval ships is to improve performance through using more electric equipment. The reliability and quality of the onboard electric power, therefore, becomes critical as the ship functionality would entirely depend on its availability. This paper investigates the possibility of using Flywheel Energy Storage Systems (FESS), similar to those earlier developed for commercial applications, to address issues related to onboard power supplies. A design of a FESS for onboard power backup and railroad electrical stations is presented. The FESSs power output parameters are 500kW×30sec in high-duty mode and up to 2MW in pulse mode. High power output is one of the main advantages of FESS over commercially available electrochemical batteries. The other advantages include essentially an unlimited number of charge/discharge cycles, observable state of charge and environmental friendliness. Designs of the main FESS components are discussed: low-loss magnetic bearings, an energy-storage hub, a high-efficiency motor/generator and power electronics.

/pdf/flywheel-energy-storage-system-for-naval-applications-35tc3p7zv9.pdf

Flywheel energy storage system for naval applications

A low cost cryogenic expander system that incorporates a high performance, high-speed permanent magnet generator and low loss magnetic bearings is described. The expander system will be used in industrial air separation plants that produce gases such as nitrogen, oxygen, and argon using a cryogenic distillation process. Magnetic bearings enable the key advantage of a completely oil-free system that reduces the risk of accidental contamination of the process. A single generator/bearing module was designed to accommodate a wide range of expander aerodynamic stages that operate at different speeds and power levels ranging from 9,000 RPM to 30,000 RPM and 10 kW to 165 kW. Shop testing of the unit to 30,000 rpm was completed in December 2003. The prototype unit will undergo additional loop testing at the system manufacturer’s facility and is scheduled for field installation in mid 2004. System design and test results are presented.

/pdf/design-and-shop-testing-of-a-165kw-cryogenic-expander-3225okdfh6.pdf

Design and shop testing of a 165kw cryogenic expander/generator on magnetic bearings

A cryogenic gas expander system that incorporates a high performance, high-speed permanent magnet, direct-drive generator and low loss magnetic bearings is described. Flow loop testing to 30,000 rpm was completed at the system manufacturer’s facility in January 2005, and field installation is scheduled for October 2005. As part of the system testing, the rotor was dropped onto the backup bearings multiple times at an intermediate speed and at 30,000 rpm. Orbit and time-history data from a full speed drop and spin down are presented and discussed in detail. A transient, nonlinear rotordynamic analysis simulation model was developed for the machine to provide insight into the dynamic behavior. The model includes the dead band clearance, the flexible backup bearing support and hard stop. Model predictions are discussed relative to the test data.Copyright © 2006 by ASME

/pdf/test-results-and-analytical-predictions-for-rotor-drop-2bs1wbe2jr.pdf

Shamim Imani

Papers

Test Results and Analytical Predictions for Rotor Drop Testing of an Active Magnetic Bearing Expander/Generator

Flywheel energy storage system for naval applications

Design and shop testing of a 165kw cryogenic expander/generator on magnetic bearings

Test Results and Analytical Predictions for Rotor Drop Testing of an AMB Expander/Generator