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Optimal placement of radiation shields in the displacer of a Stirling engine
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Development of an advanced free-piston Stirling engine for micro combined heating and power application
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Integrated two-cylinder liquid piston Stirling engine
Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harness useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.
30-kW Maintenance-Free Stirling Engine for High-Performance Dish Concentrating Solar
This final report summarizes the final results of the 30-kW Maintenance-Free Stirling Engine for High-Performance Dish Concentrating Solar project performed by Infinia Corporation for the U.S. Department of Energy under contract DE-FC36-08GO18032 during the project period of March 1, 2008 – March 31, 2012. Over the course of the project, Infinia Corporation achieved substantial progress in the design, fabrication, assembly, testing and evaluation of a 30-kW multi-cylinder, free-piston Stirling engine (MCFPSE) prototype. In this effort, prior MCFPSE conceptual design approaches were adapted for the development of a 30-kW design, thereby producing a cohesive design package and detailed performance specifications. Numerical analysis using the Stirling Engine Analysis and Optimization Code (SAGE) was completed culminating in the selection of a fully balanced 6-cylinder configuration composed of two 3-cylinder engine modules. The model was refined throughout the program to include all wall conduction losses, piston and rod seal losses, appendix, shuttle and pumping losses, and piston radiation loss to closely represent the real system. Performance mapping of the engine was then completed using the detailed model. Based on knowledge and experience from its existing commercial products, and using the results from the extensive numerical modeling discussed above, Infinia successfully fabricated, assembled and tested two sets of 30-kW engine modules. One of these configurations was driven by an external power supply and operated as a cooler in order to verify the mechanical integrity of the system. In the engine configuration, induction heaters provided the energy to the heater head to operate the engine. Considerable effort was expended on correcting problems associated with contact and rubbing of internal components, identification and subsequent elimination of internal leaks, and undesirable amounts of piston bias. Many details concerning the fabrication and testing efforts are considered proprietary. As a result, those findings are not disclosed herein but rather can be found in proprietary reports supplied to the DOE on a periodic basis. The prototype did not fully demonstrate performance nor did it realize the projected cost targets. Furthermore, the basis of the mechanical and electrical architecture of the 30-kW multi-cylinder prototype design is now at least two generations old. Alternatively, Infinia’s 8-kW Bonneville generator, which was successfully demonstrated in April 2012, and is slated to enter commercial production in late 2013, offers immediate benefits of lower cost and significantly higher power density such that the generator will likely meet DOE’s Sunshot LCOE target goal of $\$$0.07-0.10/kWh by 2015 and $\$$0.05-0.07/kWh by 2020. Therefore, the design of a 30-kW Stirling engine as disclosed in the project will not be pursued further. However, Infinia remains keenly interested in developing higher power Stirling machines in the future based on the new Bonneville mechanical design.
Alternatives to MARVEL Power Conversion – Comparison of Stirling Engine Thermal Efficiency and Design to other Power Conversion Cycles
The Microreactor Applications, Research, Validation, and Evaluation (MARVEL) Reactor is a small liquid-metal thermal reactor that will be built at the Idaho National Laboratory to demonstrate design and operating processes for microreactors, microgrid integration, and process heat applications. Power conversion in the MARVEL design is provided by Stirling engines, which have disadvantages in nuclear environments. Compared to Stirling engine performance, some alternative power cycles can increase power production when coupled to a liquid-metal thermal reactor In this paper, the thermal efficiency of MARVEL’s power production with Stirling engines is compared to the thermal efficiency of power production with MARVEL and alternative power cycles. Those cycles include a superheated Rankine cycle, open and closed Brayton cycles, and a supercritical carbon dioxide cycle. All cycles (except the Stirling engines) were modeled with an intermediate helium loop to meet MARVEL’s principal design criteria. All models are simple designs with conservative assumptions for consistent comparison. Detailed optimization will depend largely on reactor location and application, and the relative merit of each cycle is discussed for different environmental conditions. The study informs significant early decisions on power cycle design and economic
Alternatives to MARVEL Power Conversion -- Comparison of Stirling Engine Thermal Efficiency and Design to Other Power Conversion Cycles
PRESENTATION for CONFERENCE PAPER: The Microreactor Applications, Research, Validation, and Evaluation (MARVEL) Reactor is a small liquid-metal thermal reactor that will be built at the Idaho National Laboratory to demonstrate design and operating processes for microreactors, microgrid integration, and process heat applications. Power conversion in the MARVEL design is provided by Stirling engines, which have disadvantages in nuclear environments. Compared to Stirling engine performance, some alternative power cycles can increase power production when coupled to a liquid-metal thermal reactor. In this paper, the thermal efficiency of MARVEL’s power production with Stirling engines is compared to the thermal efficiency of power production with MARVEL and alternative power cycles. Those cycles include a superheated Rankine cycle, open and closed Brayton cycles, and a supercritical carbon dioxide cycle. All cycles (except the Stirling engines) were modeled with an intermediate helium loop to meet MARVEL’s principal design criteria. All models are simple designs with conservative assumptions for consistent comparison. Detailed optimization will depend largely on reactor location and application, and the relative merit of each cycle is discussed for different environmental conditions. The study informs significant early decisions on power cycle design and economics for deployment of advanced microreactors as they move from theory and concept to execution.
SPC-70486 Rev 0 Stirling Engine Prototype Performance Specification
Idaho National Laboratory (INL) is developing a small microreactor to produce electrical power utilizing a small nuclear core and Stirling engines under the Microreactor Application Research Validation and Evaluation (MARVEL) program. The purpose of this performance specification is to define requirements to build and test the Stirling Engine prototype, including interfacing with Kinnetech in the development/test of the engines. This specification includes prototyping components only and are not for use in the reactor. Prototype testing is a preliminary test to be conducted with conceptual equipment from which a final design will be developed. The results of the testing defined herein will not be used as a qualification test. The Stirling Engines have an engine controller module (QEC). Currently, the QEC doesn’t have a means to stop the engine. An analog controlled engine braking system must be developed and tested with the engine prototype. Any conflict between this specification and any supplementary specifications in the procurement documents requires written clarification from the Contractor prior to proceeding with any work. Any deviation from the procurement documents requires approval by the Contractor with the change request process.
Control system for the Stirling engine
A new control system is proposed for Stirling engines. The system is based on a sealed external system for hydrogen sorption and desorption, with a thermoelectric heating and cooling system. It is intended to improve the operational reliability and the safety of the maintenance crew; to reduce the operational noise level; and to reduce the size and mass of the motor and simplify its design.
Low-temperature Stirling Engine for Geothermal Electricity Generation
Up to 2700 terawatt-hours per year of geothermal electricity generation capacity has been shown to be available within North America, typically with wells drilled into geologically active regions of the earth's crust where this energy is concentrated (Huttrer, 2001). Of this potential, about half is considered to have temperatures high enough for conventional (steam-based) power production, while the other half requires unconventional power conversion approaches, such as organic Rankine cycle systems or Stirling engines. If captured and converted effectively, geothermal power generation could replace up to 100GW of fossil fuel electric power generation, leading to a significant reduction of US power sector emissions. In addition, with the rapid growth of hydro-fracking in oil and gas production, there are smaller-scale distributed power generation opportunities in heated liquids that are co-produced with the main products. Since 2006, Cool Energy, Inc. (CEI) has designed, fabricated and tested four generations of low-temperature (100°C to 300°C) Stirling engine power conversion equipment. The electric power output of these engines has been demonstrated at over 2kWe and over 16% thermal conversion efficiency for an input temperature of 215°C and a rejection temperature of 15°C. Initial pilot units have been shipped to development partners for further testing and validation, and significantly larger engines (20+ kWe) have been shown to be feasible and conceptually designed. Originally intended for waste heat recovery (WHR) applications, these engines are easily adaptable to geothermal heat sources, as the heat supply temperatures are similar. Both the current and the 20+ kWe designs use novel approaches of self-lubricating, low-wear-rate bearing surfaces, non-metallic regenerators, and high-effectiveness heat exchangers. By extending CEI's current 3 kWe SolarHeart® Engine into the tens of kWe range, many additional applications are possible, as one 20 kWe design produces nearly seven times the power output of the 3 kWe unit but at only 2.5 times the estimated fabrication cost. Phase I of the proposed SBIR program will therefore study the feasibility of generating electricity with one or more 20 kWe or larger Stirling engines, powered by geothermal heat produced by current and possibly some forward-looking borehole extraction methods, and from producing oil and gas wells. The feasibility study will include full analysis of the thermodynamic and heat transfer processes within the engine (necessary to produce optimum theoretical designs and performance maps), the cost of pumping the geothermal heat recovery fluid, and how the system tradeoffs impact the overall system economics. The goal is a geothermal system design that could be demonstrated during a Phase II follow-on program at a field test site.
ECAR-6573 Rev 0 PGS Stirling Engine Radiation Lifetime Estimate
This evaluation determines the expected service lifetime for the Stirling Engines in the Power Generation Subsystem (PGS) based on the radiation resistance of the organic materials, electrical components, and magnets, along with the projected radiation dose rate. Components that are not projected to last for a six-month operational period are discussed in more detail, including their associated risk due to failure and possible remedial actions.
ECAR-7813 Rev 0 Secondary Coolant Cover Gas System Stirling Engine Tube Rupture Analysis, Insulation Block Analysis, and Labyrinth Seal Design
The purpose of this ECAR is to document compliance with best engineering practices for the Secondary Coolant Cover Gas System of the MARVEL microreactor which includes a Stirling Engine helium tube rupture analysis, an analysis to verify the strength of the insulation blocks, and the design of the Labyrinth Seal.
Enabling a Flexible Grid with Increased Penetration of DER: Techno-economic Analysis of Metal Hydride Thermochemical Energy Storage Integrated with Stirling Engine for Grid Energy Storage Applications
This report summarizes the results of a techno-economic assessment of the capital and operational expenses for 3 scenarios utilizing a TES/Stirling engine system which is charged by an electric heater to provide grid power and energy storage. While there are several integration possibilities and material choices that could be utilized in such systems, three difference scenarios were chosen for this assessment to reflect an anticipated deployment of the technology where each might require different TES system configurations. Additionally, an enhanced version of the HTMH is considered to demonstrate the expected impact on costs with further technology development. The predicted capital and operational LCOS for the system configurations range from $0.0198/kWhr e - $0.0734/kWhr e which compare positively to the LCOS for lithium ion battery storage ranging from $0.087/kWhr e – $0.329/kWhr e . The key drivers for cost improvements to the system are material property enhancements in the HTMH primarily related to reducing the costs associated with the HTMH vessel and heat exchangers. This analysis demonstrates the potential benefits and flexibility of integrating a Stirling engine with a metal hydride-based TES system and suggests that the MH TES technology, at its current level of development, provides a highly competitive alternative to lithium ion batteries for large scale grid energy storage applications.
Low Temperature Stirling Engine for Geothermal Electricity Generation
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A Summary of the Fabrication of a Prototype Stirling Engine Heat Exchanger.
Abstract not provided.
A Summary of the Fabrication of a Prototype Stirling Engine Heat Exchanger.
Abstract not provided.