Browse Topic: Stirling engines

Items (146)

Quantification of Windage and Vibrational Losses in Flexure Springs of a One kW Two-Stroke Free Piston Linear Engine Alternator

2019-01-081604/02/2019

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 Prius

2018-01-0421

04/03/2018

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 Convertor

TBMG-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 Regenerator

2017-01-0148

03/28/2017

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 Model

2017-26-0029

01/10/2017

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 Engines

TBMG-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 Motion

TBMG-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) Converter

TBMG-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 2016

B-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 Engine

2014-36-0282

09/30/2014

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 Alternator

TBMG-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 Bearings

TBMG-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 Generation

2012-01-1214

04/16/2012

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 Development

2011-01-0410

04/12/2011

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 future

10AEMD0519_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 Systems

2007-01-324607/09/2007

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 Exchanger

TBMG-61

08/01/2006

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 Device

TBMG-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 100

AUTOJUN03_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 Approach

2001-01-251308/20/2001

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 Engines

TBMG-7308

04/01/2001

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 Engines

TBMG-7307

04/01/2001

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 Engine

1999-01-330809/28/1999

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 Engine

1999-01-288008/17/1999

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.

THE SECOND STIRLING TECHNO RALLY CONTEST OF MODEL AND MANNED STIRLING ENGINE CARS

1999-01-250308/02/1999

“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

Optimized Design of Stirling-Driven Vapor-Compression System

1999-01-245308/02/1999

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 Life

1999-01-246808/02/1999

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

PROPOSAL AND BASIC EXPERIMENTS OF SUPER STIRLING ENGINES

1999-01-250208/02/1999

“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

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

Evaluation of 6 Different Correlations for the Flow Friction Factor of Stirling Engine Regenerators

1999-01-245608/02/1999

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

Design and Analysis Code for Radiators of Stirling Power Systems With General Purpose (GPHS) Heat Sources

1999-01-267408/02/1999

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.

Hydrogen Permeation Issue for Gas Fired AMTEC Systems

1999-01-255708/02/1999

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.

A Study on Temperature Distribution of Stirling Engine Regenerator

1999-01-250608/02/1999

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

Basic Research on Solar Stirling Power Technology for Future Space Applications

1999-01-268108/02/1999

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

History of the Electric Automobile

R-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 Rig

TBMG-2223

02/01/1998

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