Browse Topic: Stirling engines

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Quantification of Windage and Vibrational Losses in Flexure Springs of a One kW Two-Stroke Free Piston Linear Engine Alternator2019-01-081604/02/2019
Methods to quantify the energy losses within linear motion devices that included flexural springs as the main suspension component were investigated. The methods were applied to a two-stroke free-piston linear engine alternator (LEA) as a case study that incorporated flexure springs to add stiffness to the mass-spring system. Use of flexure springs is an enabling mechanism for improving the efficiency and lifespan in linear applications e.g. linear engines and generators, cryocoolers, and linear Stirling engines. The energy loss due to vibrations and windage effects of flexure springs in a free piston LEA was investigated to quantify possible energy losses. A transient finite element solver was used to determine the effects of higher modes of vibration frequencies of the flexure arms at an operational frequency of 65 Hz. Also, a computational fluid dynamics (CFD) solver was used to determine the effects of drag force on the moving surfaces of flexures at high frequencies. A parametric
Zamani Meymian, Nima, Clark, Nigel, Subramanian, Jayaram, Heiskell, Gregory, Johnson, Derek, Mahmudzadeh, Fereshteh, Darzi, Mahdi, Musho, Terence, Famouri, Parviz
Fuel Consumption Saving Potential of Stirling Machine on Series Parallel Hybrid Electric Vehicle: Case of the Toyota Prius2018-01-042104/03/2018
Investigations on alternative fuels and new hybrid powertrain architectures have recently undergone significant efforts in the automotive industry, in attempt to reduce carbon emissions from passenger cars. The use of these fuels presents a potential for re-emerging the deployment of external combustion non-conventional engines in automotive applications, such as the Stirling engines, especially under the current development context of powertrain electrification. This paper investigates the potential of fuel consumption savings of a series-parallel hybrid electric vehicle (SPHEV) using a Stirling machine as fuel converter. An exergo-technological explicit analysis is conducted to identify the Stirling system configuration presenting the best compromise between high efficiency and automotive implementation constraints. The Stirling engine with combustion chamber preheater is prioritized. A SPHEV model is developed based on the Prius power-split hybrid electric architecture. Energy
Bou Nader, Wissam, Mansour, Charbel, Nemer, Maroun, Dumand, Clement
Alpha-STREAM ConvertorTBMG-2719807/01/2017
Innovators at NASA’s Glenn Research Center have developed two novel technologies that make Stirling engines more efficient and less costly. First, Glenn’s thermoacoustic power converter uses sound to turn heat into electric power. Utilizing heat-driven pressures and volume oscillations from thermoacoustic sources to power piezoelectric alternators or other power-converter technologies, this device can generate electricity with unprecedented efficiencies. Unlike conventional Stirling-based devices, this thermoacoustic engine achieves high thermal-to-electrical efficiencies with no moving parts. Glenn’s second advancement for Stirling engines replaces the conventional linear alternator with a magnetostrictive alternator that converts the oscillating pressure wave into electric power (see figure). These innovations offer a reliable and efficient way to generate power from any heat source, benefiting applications such as combined heat and power (CHP) systems, distributed generation, solar
Experimental and Numerical Study of Porosity Gradient in a Stirling Engine Regenerator2017-01-014803/28/2017
The approaching the ideal efficiency assumption is possible in Stirling engine. Regenerator is the main component in improving the efficiency of the engine. Besides the Geometry and materials of the regenerator, amount and quality of porosity have significant impacts on the regenerator performance which is focused on this research. The main idea of this study is to evaluate the effect of porosity, or unsymmetrical porosity gradient in pressure drop and the thermodynamic performance of regenerator, so three models of regenerator are developed and analyzed: First, a model in which the porosity is constant and do not change (Common mode). In the Second model, the length of regenerator porosity is changed from high to low and in the third model, the length of regenerator porosity is changed from low to high. All versions of models have the same global porosity. Each of these models is separately simulated in Ansys software and validated with experimental results from a laboratory sample
Arab, Majid, Majidi, Majid
Automobile Exhaust Gas Heat Energy Recovery Using Stirling Engine: Thermodynamic Model2017-26-002901/10/2017
Higher fuel economy of the vehicle is a critical concern in automobile industry. Traditional internal combustion (IC) engines waste a large portion of the available fuel energy as heat loss via exhaust gas. This proposal aims at recovering the available exhaust heat of the IC engines using stirling engine (SE) as an add-on device. SE is a type of cyclic heat engine which operates by compression and expansion of the working fluid, at different temperature levels resulting in a conversion of the heat energy into mechanical work. A thermodynamic analysis is performed on the chosen beta SE rhombic drive configuration with different combinations of design parameters like working fluid mass, total dead volume, thermal resistance, and hot side and cold side temperatures. A regenerator temperature model is developed to account for first law consistency in the regenerator section of SE, along with heat transfer in accordance with mass flow within the regenerator. In conclusion, the results
Saxena, Shubham, Ahmed, Mudassir
Mechanisms for Achieving Non-Sinusoidal Waveforms on Stirling EnginesTBMG-2614901/01/2017
The current state-of-the-art Stirling engines use sinusoidal piston and displacer motion to drive the thermodynamic cycle and produce power. Research performed at NASA Glenn has shown that non-sinusoidal waveforms have the potential to increase Stirling engine power density, and could possibly be used to tailor engine performance to the needs of a specific application. However, the state-of-the-art Stirling engine design uses gas springs or planar springs that are very nearly linear, resulting in a system that resonates at a single frequency. This means that imposing non-sinusoidal waveforms, consisting of multiple frequencies, requires large forces from the drive mechanism (either the alternator or the crank shaft). These large forces increase losses, and increase the size and requirements of the control system. This innovation aims to reduce the external forcing requirements by introducing internal mechanical components that provide the forces necessary to achieve the desired
Improving Stirling Engine Performance Through Optimized Piston and Displacer MotionTBMG-2615201/01/2017
Stirling engines typically achieve high efficiency, but lack power density. Low power density prevents them from being used in many applications where internal combustion engines are viable competitors, and increases system costs in applications that require Stirling engines. This limits their operating envelope in both terrestrial and space applications. Sinusoidal piston and displacer motion is one of the causes of low power density. Previous work proposed solving this problem by replacing sinusoidal waveforms with waveforms that more closely approximate those of the ideal Stirling cycle. However, when working with real engines, imposing ideal waveforms has been shown to reduce power density and efficiency due to increased pressure drop through the regenerator and heat exchangers.
Double-acting Extremely Light Thermo-Acoustic (DELTA) ConverterTBMG-2494807/01/2016
Power generation from an external or internal heat source using thermal energy conversion technologies such as solid-state thermionics and thermoelectrics or dynamic conversion with Otto, Stirling, Brayton, or Rankine technologies is fundamentally limited in maximum specific power due to either low efficiency and/or operating frequency. These solid-state technologies are low voltage and hence produce a high DC current that restricts their minimum geometry to approximately 4 A/mm2 to avoid overheating. High-power implementations of this technology class are inefficient, large, and heavy.
Honda R&D Technical Review April 2016B-HON-01904/01/2016
Honda's April 2016 R&D Technical Review features cutting-edge developments and new ways of solving engineering problems from Honda's worldwide R&D teams. This edition brings 23 technical papers and provides featured topics that include: • Development of New Fuel Cell Vehicle CLARITY FUEL CELL • Development of RC213V-S • Introduction of Heat Exchanger Production Technique for Stirling Engine Using Additive Manufacturing
Numerical Computational Optimization Applied To The Dynamic Behavior of an Articulated Cursor, Connecting Rod and Crank Mechanism - Case Studies for Implementing a Beta Stirling Engine2014-36-028209/30/2014
The Stirling engine is a device that has great potential for being used in applications where energy (heat) is available in the system. As an example, a Stirling motor can use the energy available in the gases from the combustion process of an automotive engine by using exhaust manifold as hot source. The Stirling motor consists of a piston that can move along a cylinder that is fulfilled by a working fluid and a displacer installed between the hot and cold chambers. Due to the large temperature difference between the chambers, it becomes feasible to use the corresponding energy to drive the Stirling engine. For design purposes, a multi-objective problem is formulated so that the maximization of thermodynamic efficiency, the minimization of energetic loss associated with the movement of the displacer set, and the minimization of energetic loss related to the fluid displacement between the two chambers is obtained for the optimal configuration of the system. To solve this optimal design
de Paula Brito, Gelcino, Borges, José Antônio Ferreira
Magnetostrictive AlternatorTBMG-1767411/01/2013
This innovation replaces the linear alternator presently used in Stirling engines with a continuous-gradient, impedance-matched, oscillating magnetostrictive transducer that eliminates all moving parts via compression, maintains high efficiency, costs less to manufacture, reduces mass, and eliminates the need for a bearing system.
Cascading Tesla Oscillating Flow Diode for Stirling Engine Gas BearingsTBMG-1484810/01/2012
Replacing the mechanical check-valve in a Stirling engine with a micromachined, non-moving-part flow diode eliminates moving parts and reduces the risk of microparticle clogging.
Temperature Controlled Exhaust Heat Thermoelectric Generation2012-01-121404/16/2012
The amount of energy wasted through the exhaust of an Internal Combustion Engine (ICE) vehicle is roughly the same as the mechanical power output of the engine. The high temperature of these gases (up to 1000°C) makes them intrinsically apt for energy recovery. The gains in efficiency for the vehicle could be relevant, even if a small percentage of this waste energy could be regenerated into electric power and used to charge the battery pack of a Hybrid or Extended Range Electric Vehicle, or prevent the actuation of a conventional vehicle's alternator. This may be achieved by the use of thermodynamic cycles, such as Stirling engines or Organic Rankine Cycles (ORC). However, these systems are difficult to downsize to the power levels typical of light-vehicle exhaust systems and are usually bulky. The direct conversion of thermal energy into electricity, using Thermoelectric Generators (TEG) is very attractive in terms of minimal complexity. However, current commercial thermoelectric
P. Brito, Francisco, Martins, Jorge, Goncalves, L.M., Sousa, Rui
High Efficiency Internal Combustion Stirling Engine Development2011-01-041004/12/2011
A unique engine, based on the regenerative principle, is being developed with the goal of achieving high brake efficiency over a wide power range. It can be characterized as an internal combustion Stirling engine (ICSE). The engine is a split-cycle configuration with a regenerator between the intake/compression cylinder and the power/exhaust cylinder. The regenerator acts as a counter-flow heat exchanger. During exhaust, the hot gases are cooled by the regenerator. The regenerator stores this heat. On the next cycle, compressed gases flow in the opposite direction and are heated by the regenerator. The gases coming from the regenerator into the power cylinder are very hot (~900°C), which provides the necessary gas temperature for auto-ignition of diesel and other fuels. A simplified Air Cycle analysis of the ICS engine is presented to validate the concept thermodynamics and to show the inherent difference between the ICS and conventional internal combustion engine (ICE) indicated
Patton, Richard, Bennett, George
Heading back to the future10AEMD0519_0105/19/2010
As the buzz about space grows, and with the potential for government resurrection of funding, materials for space travel-and materials creation in space-are taking on new life. New materials for space applications can be exceptionally expensive to develop, and expensive has not been a positive concept in the space community for many years. Never mind the technology spin-offs from space exploration; give no consideration to the advances in metals, composites, electronics, you name it-all of which have moved ahead since the 1950s thanks to rocket and space research. The national dismay and envy around Sputnik translated into government dollars. Not surprisingly, project numbers rose when funding was the most free and the romance of space travel caught the fancy of the public. Today, time has dimmed the romance, national pride has taken a back seat to international projects, and there have been high-profile reminders that life in space is precarious. The result: relatively low research
Gayman, David
Development of a Single-Fluid Consumable Infrastructure for Life Support Systems2007-01-324607/09/2007
Decomposition of high-grade hydrogen peroxide (H2O2) generates water vapor, oxygen, and heat. By converting heat to electrical energy with a Stirling engine, a spacesuit portable life support system can be maintained exclusively with H2O2; however, incorporation of additional cooling water may reduce the overall system mass. System components comprising the hydrogen peroxide portable life support system (HyPerPLSS) are discussed and analyzed. Component considerations and thermodynamic relations indicate an optimal hydrogen peroxide concentration of 95%. Life support requirements for eight hours of extravehicular activity are satisfied with 10.9 kg of liquid H2O2.
Lewandowski, Craig M., Akin, David L.
Microscale Regenerative Heat ExchangerTBMG-6108/01/2006
The device illustrated in Figure 1 is designed primarily for use as a regenerative heat exchanger in a miniature Stirling engine or Stirling-cycle heat pump. A regenerative heat exchanger (sometimes called, simply, a “regenerator” in the Stirling-engine art) is basically a thermal capacitor: Its role in the Stirling cycle is to alternately accept heat from, then deliver heat to, an oscillating flow of a working fluid between compression and expansion volumes, without introducing an excessive pressure drop. These volumes are at different temperatures, and conduction of heat between these volumes is undesirable because it reduces the energy-conversion efficiency of the Stirling cycle. Hence, among the desired characteristics of a regenerative heat exchanger are low pressure drop and low thermal conductivity along the flow axis.
Thermoelectric Air/Soil Energy-Harvesting DeviceTBMG-52210/01/2005
A proposed thermoelectric device would exploit natural temperature differences between air and soil to harvest small amounts of electric energy. Because the air/soil temperature difference fluctuates between nighttime and daytime, it is almost never zero, and so there is almost always some energy available for harvesting. Unlike photovoltaic cells, the proposed device could operate in the absence of sunlight. Unlike a Stirling engine, which could be designed to extract energy from the air/soil temperature difference, the proposed device would contain no moving parts. The main attractive feature of the proposed device would be high reliability. In a typical application, this device would be used for low-power charging of a battery that would, in turn, supply high power at brief, infrequent intervals for operating an instrumentation package containing sensors and communication circuits.
Ford turns 100AUTOJUN03_0306/01/2003
Pausing to celebrate its many technical achievements of the past century, Ford maintains its focus on being an innovation leader for the next 100 years. One hundred years of existence is quite an accomplishment for any company, particularly for one in an industry that's as globally competitive as the automotive industry. Weathering two World Wars, the Great Depression, the challenges of constantly evolving to suit consumer demands of the time, not to mention some personal rough spots such as the tire-recall incident in 2000, Ford Motor Co. has managed to not merely survive throughout the past century, but to succeed.
Gehm, Ryan, Ludvigsen, Karl
Performance of Stirling Engine Hybrid Electric Vehicles: A Simulation Approach2001-01-251308/20/2001
Hybrid Vehicles have gained momentum in the automotive industry. The joint action of power sources and energy storage systems for energizing the vehicle improves the vehicle's fuel economy while reducing its pollutant emissions and noise levels, challenging automotive designers to optimize vehicle's cost, weight and control. The marketing success of hybrid vehicles significantly depends on the selection, integration and cost of the energy systems. The internal combustion engine, dominant of the vehicle market, has been the “option of choice” for auxiliary power unit of the hybrid vehicle, although other power sources as fuel cells, Stirling engines and gas turbines have been employed as well [1]. This document is focused in the application of Stirling engines as the power source for automobile propulsion. In order to optimize this process, a simulation tool for Stirling vehicle was developed based in ADVISOR, a proven hybrid electric vehicle simulation software, and MARWEISS, a
Figueroa, Luis, Fauvel, Owen R., Reader, Graham T.
Using Artificial Neural Networks To Monitor Stirling EnginesTBMG-730804/01/2001
An important secondary topic addressed in the research and development effort described in the preceding article is the use of artificial neural networks to improve the monitoring and thus the control and safety of multiple free-piston Stirling engines. Information collected by monitoring subsystems constitutes essential feedback for use by control and safety subsystems. This information includes such externally measurable quantities as heater-head temperatures, motions of engine housings, and output currents and voltages.
Dynamic Balancing of Multiple Independent Stirling EnginesTBMG-730704/01/2001
Experiments have shown that an assembly of multiple free-piston Stirling engines can be designed and constructed in such a way as to both (1) make the vibrations of the engines balance each other to minimize the overall level of vibration, and (2) enable the engines to operate independently of each other, so that if one fails, the other(s) can continue to provide power. Prior to these experiments and to the research and development effort that preceded them, it was not possible to achieve both redundancy and suppression of vibrations: The only previously demonstrated method to balance out vibrations of multiple Stirling engines was by use of counter-oscillating pistons coupled to each other via a common thermodynamic hot space, with the engines driving linear alternators connected electrically in series. This older scheme precludes redundancy because the common thermodynamic interaction and the series electrical connection causes both engines to fail when one fails.
Study on Design and Performance Prediction Methods for Miniaturized Stirling Engine1999-01-330809/28/1999
This paper shows a design and performance prediction methods for a miniaturized Stirling engine, in order to develop a small portable generator set. First, a 100 W class Stirling engine is designed and manufactured. In order to miniaturize the engine, unique type heat exchangers were applied. A regenerator was located in a displacer piston. For a piston drive mechanism, a Scotch-yoke mechanism which was useful to realize the small-size engine without any lubricating device, was adopted. Next, an analysis model for the miniaturized engine is developed to improve the engine performance efficiently. The pressure in the working space is analyzed by an isothermal analysis which takes into account a gas leakage through a piston ring and pressure loss in the heat exchangers. To estimate a shaft power, the mechanical loss and the buffer loss, which is caused by a pressure change in a crank case are considered on the analysis model. The calculated results were compared with the experimental
Hirata, Koichi, Iwamoto, Shoichi
Afterburning Ericsson Cycle Engine1999-01-288008/17/1999
Initial development of an afterburning Ericsson cycle engine is described. The recently developed engine integrates the Ericsson cycle power producing processes (compression, heating, expansion, and cooling) with the combustion process. This cycle is capable of high thermodynamic efficiency and provides complete, continuous, combustion. The cycle offers the opportunity to achieve the high efficiencies that are promised by Stirling engines but have not been achieved in practice. Unlike Stirling engines, there is no efficiency lost in an external burner by having to heat the combustion air from ambient temperature. Instead, combustion is initiated at the high temperature of the isothermal expander exhaust. The flame temperature combustion products then transfer heat to the expander while cooling back to the expander temperature. In this manner, all the heat of combustion is available to the cycle. The afterburning Ericsson cycle engine can potentially use mostly conventional internal
Proeschel, Richard A.
Hydrogen Permeation Issue for Gas Fired AMTEC Systems1999-01-255708/02/1999
Diffusion of hydrogen in solids is an intriguing intellectual problem. Permeation of hydrogen generated in combustion into gas fired Alkali Metal Thermal to Electric Converter (AMTEC) systems can be detrimental to AMTEC performance for various reasons. Potential effects include depriming of the AMTEC cell arteries, blockage of the condenser and hydride formation. Numerous papers and reports have been published concerning hydrogen diffusion in solids (Birnbaum and Wert, 1972; Garber, 1975; Strehlow and Savage, 1974). Many of these papers concern the embrittling effects of hydrogen and many concern the diffusion process itself. Hydrogen permeation and permeation resisting strategies have been examined extensively in connection with other energy conversion technologies such as Stirling engines (Alger, 1988; Khalili etal., 1989) and high temperature heat pipes (Anderson et al., 1995; North and Anderson, 1997). Due to the different boundary conditions and materials involved, it was
Mital, R., Butkiewicz, D. A., Childs, K. F., Hayes, D. D., Svedberg, R. C., Hunt, T. K.
THE SECOND STIRLING TECHNO RALLY CONTEST OF MODEL AND MANNED STIRLING ENGINE CARS1999-01-250308/02/1999
“The Second Stirling Techno Rally” is held at Nov. 1998 near Tokyo. This time about 100 normal size cars (N-class) and 30 mini cars (M-class) came to the contest and got better records than last year. Moreover, for this second rally, race of manned big cars and bikes (L-class) with self made Stirling engines are taken place also, and, about ten cars came to the race. The preparation and wonderful results of this second techno rally are reported here in details. By those rallies, it is hoped that understanding and progress of Stirling engine itself will be stimulated very much towards glorious 21st century.
ISSHIKI, Naotsugu, FUJII, Iwane, MATSUO, Masahiro, ISSHIKI, Seita
Design and Analysis Code for Radiators of Stirling Power Systems With General Purpose (GPHS) Heat Sources1999-01-267408/02/1999
An efficient finite difference (FD) computational code has been developed for the analysis and design of circular sector radiators for linear alternator output “Free Piston Stirling Engine” space power systems utilizing a radioisotope Pu-238 General Purpose (GPHS) heat source. The code calls on a subroutine developed by the author to solve the second order, fourth degree, ordinary differential equation (ODE) of a fin (extended heat transfer surface) radiating to the space environment. Although the code was originally written for a rectangular coordinates system, it was transcribed into polar (cylindrical) coordinates for the present application. The circular sector radiator panel analyzed has an embedded heat pipe at an arbitrary radial location conducting cycle reject heat from the Stirling engine cold end to the radiator. For a required radiator heat load and a given set of geometrical and thermo-physical properties of the radiator sector, the code will compute the required radiator
Juhasz, Albert J., Thieme, Lanny G.
A Study on Temperature Distribution of Stirling Engine Regenerator1999-01-250608/02/1999
The performance of Stirling engines depends on the performance of regenerators. Regenerators are primarily expected to have good temperature efficiency. In addition, the flow losses and dead space must be minimized. These factors, however, are in opposition to each other. Although a considerable amount of research has focused on these three factors, few studies have analyzed them in actual reciprocating flows. Moreover, it has not been possible to measure the temperature efficiency by using a working gas due to the rapid change of the gas temperature. Therefore, in this study, we measured the transition of the temperature in the reciprocating flows in a regenerator by using water instead of a gas and then examined the characteristics of the regenerator. Here, we report the observed transition of temperature, which almost coincided with results previously obtained by computer simulation.
Watanabe, Hiroichi, Fujisawa, Yuichi, Yoshida, Munenobu, Moriya, Shinji, Ohtomo, Michihiro, Isshiki, Naotsugu
Optimized Design of Stirling-Driven Vapor-Compression System1999-01-245308/02/1999
Stirling engines have many unique advantages including higher thermal efficiencies, preferable exhaust gas characteristics, multi-fuel usage, and low noise and vibration. On the other hand, heat pump systems are very attractive for space heating and cooling and industrial usage. There are several environmental merits of Stirling-driven vapor-compression (SDVC) systems. A design method for the SDVC, which is based on mathematical methods for Stirling and Rankine cycles, has been developed. The model treats a kinematic Stirling engine and a scroll compressor which are coupled by a belt. The measured performance of an actual system well agreed with the calculated results. The attractive SDVC performance using conventional and alternative refrigerants was shown. From the calculated Total Equivalent Warming Impact, TEWI and operating costs, it became clear that the SDVC system with the alternative refrigerant has a higher potential as the future air-conditioning system.
Kagawa, Noboru
New Energy Management Technology Gives Hybrid Cars Long Battery Life1999-01-246808/02/1999
New energy-and-power management technology makes low-pollution hybrid electric vehicles practical and competitive in performance with gasoline powered cars. The fuel-burning engine can now run at its most efficient speed and load, with the propulsion motor supplying acceleration power and the generator capturing deceleration power. Battery depth of discharge can be monitored and controlled to get long battery life. A heavy battery is not needed for long travel distance. For example, the new Toyota Prius hybrid car delivers 66 miles per gallon in city driving and has a range of 600 miles on a tankful of gasoline. When acceleration power is supplied from a battery, then the engine can be a high-efficiency type, such as the 43-percent efficient Meijer version of the Stirling-cycle engine. Hydrogen, a previously impractical engine fuel, can be burned in external-combustion Stirling engines. Hydrogen can now be compactly stored in carbon nano-tubes or lithium aluminum tetrahydride. A new
Oman, Henry
Evaluation of 6 Different Correlations for the Flow Friction Factor of Stirling Engine Regenerators1999-01-245608/02/1999
The topic of this paper is to compare six well known and often used correlations for the flow friction factor of Stirling engine regenerators /1-5/. Therefore, the experimental methods and the geometric constraints in terms of the ranges of wire diameter and porosity investigated are summarized for each correlation. Additionally, the different equations for Reynolds number and flow friction factor are discussed in order to derive one general applicable set of equations for the Reynolds number and the friction factor. Using these general equations, it is possible to show all data in one plot, which gives a good impression of the characteristics of each set of data and the deviations among them. Additionally, the correlations are applied to a 2nd order computer model (PROSA), which was used to recalculate the performance of the well known GPU-3 engine. The results of these calculations in terms of regenerator pressure drop, mechanical power output and efficiency are also presented in the
Thomas, Bernd
Performance Modeling of 5th Generation Heat-Assisted Stirling Heat Pump (E-3)1999-01-270008/02/1999
This paper describes recent results in a project at KUBOTA to develop a multi-fuel gas engine driven Stirling heat pump. It is mainly driven by engine shaft power and is partially assisted by thermal power from the engine exhaust heat source. We have previously developed the D-3 machine, the fourth generation prototype of the heat-assisted Stirling heat pump. Performance simulations of the next (E-3) machine are presented in conjunction with driving engine characteristics. System matching and optimization criteria and constraints are discussed with implications for performance. This machine uses helium gas as a working gas and is constructed as two 3-cylinder sets, each a combination of two Stirling sub-systems (one a power producer and one a heat pump). Utilizing both shaft power and thermal power, performance is controlled by phase shifting of the hot-side pistons to adjust the absorbing of thermal power. This heat pump system is expected to produce cooling and heating water at high
Yagyu, Sumio, Fujishima, Ichiro, Fukuyama, Yuji, Morikawa, Tomoyuki, Corey, John, Isshiki, Naotsugu, Satoh, Isao
Basic Research on Solar Stirling Power Technology for Future Space Applications1999-01-268108/02/1999
A semi free-piston Stirling engine alternator, called NALSEM500, has been experimentally studied since April 1994, as part of a space solar power technology program in NAL (National Aerospace Laboratory). The Stirling alternator is one of candidates for future space power applications, and will be integrated with the solar cavity receiver subsystem, having both Na heat pipes and thermal energy storage. Through a series of preliminary bench tests, it was found that the efficiency of the linear alternator was significantly low as compared to our initial design. To improve the alternator performance, some design modifications of the magnet assembly and stator core have been made. As a result, the thermodynamic efficiency of 33% and system efficiency of 20% was obtained.
Hoshino, Takeshi, Fujihara, Tsutomu, Eguchi, Kunihisa
PROPOSAL AND BASIC EXPERIMENTS OF SUPER STIRLING ENGINES1999-01-250208/02/1999
“Super Stirling Engine” is a Stirling engine assisted by saturated low pressure steam or compressed air of 0.2 ∼ 0.8 Mpa pressure range, which is injected into the cold side of the displacer cylinder at the top dead center of the power piston, and the steam or air expands into power cylinder at constant high temperature after passing regenerator and heater. Near the bottom dead center of the power piston, the steam or air is ejected to outside in low temperature after passing the regenerator again as same as Stirling engine. So, this engine works in the combination of Stirling cycle and steam Rankine cycle when steam is used.
ISSHIKI, Naotsugu, KOJIMA, Hiroshi, USHIYAMA, Izumi, ISSHIKI, Seita
History of the Electric AutomobileR-18710/01/1998
For more than a century, people have attempted to harness electricity, the clean and versatile fuel, for personal transportation. With impressive technical clarity and historical insight, author Ernest Wakefield reviews these attempts in History of the Electric Automobile: Hybrid Electric Vehicles. He focuses exclusively on electric vehicles that harness the potential of electricity when combined with another energy source - hybrid electric vehicles (HEV). The book details the historical development of capacitors, engines, flywheels, fuel cells, inductive charging, and solar cells - and the application of each to hybrid electric vehicles.
Wakefield, Ernest H.
Oscillating-Flow Heat-Transfer and Pressure-Drop Test RigTBMG-222302/01/1998
The figure illustrates an apparatus for measuring heat-transfer and pressure-drop characteristics of porous plug specimens in oscillating flows. The apparatus is built around an oscillating-flow test rig that was originally designed for pressure-drop (but not heat-transfer) measurements and has since been modified and refined. The flows and specimens are chosen to be representative of those encountered in the regenerators of Stirling engines.
Using a Stirling Engine Simulation Program as a Regenerator Design Aid95009702/01/1995
The regenerator in Stirling engines has long been recognized as a critical component as far as engine performance is concerned. Yet there are little or no formal Stirling engine regenerator design procedures to be found in the literature. A design procedure is proposed that makes use of a third order Stirling engine simulation program to predict the optimum regenerator configuration for the respective requirements of maximum engine power and efficiency. Tests were conducted to determine the heat transfer coefficient and pressure drop characteristic of a popular regenerator material.
Smook, W. G., Naude, A. F.
Effective Energy Utilization and Emission Reduction of Exhaust Gas in a Two-Stroke Cycle Engine — Part II93239409/01/1993
This paper deals with a research project concerning an effective utilization of exhaust gas heat. Exhaust gas from a exhaust gas-separate type two-stroke cycle engine containing a high concentration of unburned gas was temporarily stored in a floating-bell type tank as an form of heat energy conservation, while in the previous report [1]* exhaust heat was recovered with continuous operation. A Stirling engine with a hot-water supply system was then used to oxidize or burn again the exhaust gas in a catalyzer and an after-burner unit in order to recover the unspent heat energy from the exhaust gas. A three-way catalyzer was employed to remove pollutants both from the combustion gas in this process and the high-concentration burned gas from the two-stroke cycle engine. The results of the research in the present paper are intended as a follow-up of the previous report [1] to clarify a method for the more effective use of exhaust gas heat. Similarly to the results presented in the previous
Sato, Kazuo, Nakano, Masamitsu, Ukawa, Haruo
Application of the Fluidyne in Developing Countries92938908/03/1992
The Fluidyne, or liquid piston stirling engine, has many characteristics which make its use in developing nations particularly attractive. Besides being compatible with the use of lowgrade heat sources, the machine is simple to manufacture using a variety of low cost materials and is exceedingly reliable. This paper uses a summary of fluidyne experience to evaluate applications of the fluidyne to water pumping requirements in developing countries for purposes including domestic, livestock, and irrigating uses for water pumping. Possible sources of energy are evaluated in the light of availability and needs. Environmental, economic, and social benefits are also examined. Particular applications of the fluidyne to existing situations in China are evaluated in detail.
Yu, L., Fauvel, R., Reader, G., Walker, G.
Heat-Pipe Heat Transport System for Stirling Space Power Converter92939908/03/1992
Life issues relating to a sodium-heat-pipe heat transport system are discussed. The heat-pipe system provides heat, at a temperature of 1050 K, to a 50-kWe Stirling engine/linear alternator power converter called the Stirling space power converter (SSPC). The converter is being developed under a National Aeronautics and Space Administration program. Because corrosion of heat-pipe materials in contact with sodium can affect the life of the heat pipe, a literature review of sodium corrosion processes was performed. It was found that impurity reactions, primarily oxygen, and dissolution of alloy elements were the two corrosion processes likely to be operative in the heat pipe. Approaches that are being taken to minimize these corrosion processes are discussed.
Alger, Donald L.
Study on Stirling Engine Combustor92940208/03/1992
In order to achieve NOx reduction by modification of the combustor and/or the combustor arrangement in Stirling engine, the effect of several parameters on NOx emission was investigated experimentally. The combination of appropriate “distance”, swirl intensity and burner throat configuration reduces the NOx emission without EGR(Exhaust Gas Recirculation) or any other countermeasures. The NOx and CO emissions obtained are within the Japanese exhaust gas regulation code (NOx<150ppmV, CO<100ppmV at residual Oxygen 5%) for 20kW class gas boiler. In addition, the effect of the parameters on the distributions of the chemical species, burned gas temperature and ion current in the combustion chamber of the model combustor was studied experimentally to grasp the combustion process.
Koseki, Hidenori, Fujiwara, Michio, Sigimoto, Teruo
Management of the CO2 Produced in Fossil Fuelled Stirling Engine Power Systems92940308/03/1992
One of the many advantages perpetually claimed for the external combustion Stirling engine over it's internal combustion (IC) contemporaries is that it produces lower exhaust pollutants. However, this claim was made before carbon dioxide (CO2) was identified as one of the most important contributors to the undesirable greenhouse effect. Unfortunately, the more efficient combustion of a Stirling system results in proportionately more CO2 being produced than with an equivalent IC engine. Therefore, if the Stirling is to maintain it's position as an environmentally friendly engine, then some efficient means of removing the exhaust CO2 must be found. Of the many techniques available for removing this gas, the cryo-process appears to be well suited for use with the Stirling. However, a rudimentary analysis, presented in this paper, of such a system has indicated that the performance penalties imposed by making provision for CO2 removal would probably be unacceptable.
Mathews, J., Reader, G. T., Walker, G.
Update on the Advanced Stirling Conversion System Project for 25 kW Dish Stirling Applications92918408/03/1992
Under the Department of Energy's (DoE) Solar Thermal Technology Program, Sandia National Laboratories is evaluating heat engines for terrestrial Solar Distributed Heat Receivers. The Stirling engine has been identified by Sandia as one of the most promising heat engines for terrestrial applications. The Stirling engine has the potential to meet DoE's performance and cost goals [1]. The NASA Lewis Research Center is providing management of the Advanced Stirling Conversion System (ASCS) Project through an Interagency Agreement with the DoE. NASA Lewis is conducting technology development for Stirling convertors directed toward a dynamic power source for space applications. Space power requirements include high reliability with long life, high system efficiency and low vibration. The free-piston Stirling engine has the potential for both solar and nuclear space power applications. Although the space and terrestrial applications appear to be quite different, their requirements are
Shaltens, Richard K., Schreiber, Jeffrey G., Wong, Wayne A.
Double-Acting Stirling Engine with the Inner Heat Exchangers92939808/03/1992
Scientific research programmes of our Institute include development and construction of an effective Stirling engine and studies of a Stirling heat pump. According to this planned Stirling engine programme, a four-cylinder, double-action Stirling engine was designed, constructed and explored experimentally, with a regenerator having not less than 98% effectiveness. Theoretical calculations and analysis of published data on Stirling engines led to an understanding of why engines with piston swept volume greater than 100-150 cubic centimeters have comparatively low thermal efficiency. The relation between engine thermal efficiency and F/V, that is, cylinder inner heat exchange area to cylinder working fluid volume ratio has been established. With the purpose of determining the influence of inner heat exchangers upon engine thermal efficiency and to evaluate the acceptable range of ratio F/V we constructed and tested the above mentioned four-cylinder double-acting Stirling engine. Engine
Alexandravichus, T. A.
The Power Formula for Atmospheric Stirling Engines92902708/03/1992
A new proposed formula allows the evaluation of the indicated power of an atmospheric Stirling engine by means of minimum working fluid volume, mean arithmetical pressure difference and correction factors for dead space and compression ratio, grounded on the simplest geometrical and design characteristics. The practical example given in this paper presents the comparison among the Beale formula and other similar equations, developed by other authors, showing various accuracy. Closer approximation has been reached by the proposed formula in comparison with other expressions.
Kolin, Ivo, Lista, Paolo, Naso, Vincenzo
Simple Analysis of Nickel Transport in Heat Pipes of Stirling Engine Power Conversion Systems92940008/03/1992
This simple theoretical analysis of container dissolution, transport, and deposition in a sodium-filled, high-nickel superalloy heat pipe is intended to illustrate some of the issues involved in the application of such alloys to liquid metal heat transport systems such as the heat pipe for the Stirling Space Power Converter. As a first step, a cylindrical heat pipe is considered, but in principle the analysis could be extended to the complex Stirling heat pipe. In the analysis, it has been necessary to adapt corrosion rate data from pumped loops. The numerical results should not be used to form judgments about the feasibility of using superalloys in the system. Rather, they may suggest avenues of experimental investigation into the problem. They may also provide impetus for studying means of control, such as coatings.
Tower, Leonard K.
Energy Source Selection for Stirling Engine Driven AUV's92940408/03/1992
Many non-renewable land-based resources are becoming depleted and the search for alternative sources of raw materials is intensifying. This situation has lead to the involvement of a number of countries, especially those of the European Community, in heavily funded ‘Wealth from the Oceans’ projects. A significant element of the research being conducted under the auspices of these projects is concerned with the development of small unmanned and untethered autonomous underwater vehicles (AUVs). To carry out their intended autonomous missions these vehicles will need reliable power systems which have high energy densities. However, although research into navigation, control and command systems has progressed considerably under this development effort, only limited headway has been made in the development of power systems which could be readily integrated into these vessels. Electrochemical power systems have been used in underwater applications for a number of years but those presently
Potter, I. J., Reader, G. T., Walker, G.
NASA Lewis Stirling SPRE Testing and Analysis with Reduced Number of Cooler Tubes92939608/03/1992
Free-piston Stirling power converters are a candidate for high capacity space power applications. The Space Power Research Engine (SPRE), a free-piston Stirling engine coupled with a linear alternator is being tested at the NASA Lewis Research Center in support of the Civil Space Technology Initiative. The SPRE is used as a test bed for evaluating converter modifications which have the potential to improve converter performance and for validating computer code predictions. Reducing the number of cooler tubes on the SPRE has been identified as a modification with the potential to significantly improve power and efficiency. This paper describes experimental tests designed to investigate the effects of reducing the number of cooler tubes on converter power, efficiency and dynamics. Presented are test results from the converter operating with a reduced number of cooler tubes and comparisons between this data and both baseline test data and computer code predictions.
Wong, Wayne A., Cairelli, James E., Swec, Diane M., Doeberling, Thomas J., Lakatos, Thomas F., Madi, Frank J.
A Free-Piston Stirling Engine/Linear Alternator Controls and Load Interaction Test Facility92926408/03/1992
A test facility at NASA Lewis has been assembled for evaluating: free-piston Stirling engine/linear alternator control options, and interaction with various electrical loads. This facility is based on a “SPIKE” engine/alternator. The paper describes the engine/alternator, a multi-purpose load system, a digital computer based load and facility control, and a data acquisition system with both steady-periodic and transient capability. Preliminary steady-periodic results are included for several operating modes of a digital AC parasitic load control. Preliminary results on the transient response to switching a resistive AC user load are discussed.
Rauch, Jeffrey S., Madi, Frank J., Kankam, M. David, Santiago, Walter
Further Evaluations of Low-Temperature Difference Stirling Engine Characteristics92902208/03/1992
Low temperature-difference Stirling engines, while of limited perceived applicability, offer excellent opportunities to challenge the existing state of theoretical knowledge with low-cost yet revealing experimentation. The general availability of a well-performing low-cost Ringbom-Stirling engine provides an excellent basis for widespread experimentation based upon a common platform. Whereas some broad characteristics of this engine have already been presented this paper addresses in particular a number of aspects in regard to displacer springing. Most particularly, the gravitational effects on a vertically-oriented free displacer may be inferred with reference to a spring-suspended displacer. At the same time, theoretical predictions regarding sprung-displacer performance can be tested.
Fauvel, O. R., Reader, G. T., Walker, G.
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