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Sample records for stirling dynamic isotope

  1. Small Stirling dynamic isotope power system for robotic space missions

    International Nuclear Information System (INIS)

    Bents, D.J.

    1992-08-01

    The design of a multihundred-watt Dynamic Isotope Power System (DIPS), based on the US Department of Energy (DOE) General Purpose Heat Source (GPHS) and small (multihundred-watt) free-piston Stirling engine (FPSE), is being pursued as a potential lower cost alternative to radioisotope thermoelectric generators (RTG's). The design is targeted at the power needs of future unmanned deep space and planetary surface exploration missions ranging from scientific probes to Space Exploration Initiative precursor missions. Power level for these missions is less than a kilowatt. The incentive for any dynamic system is that it can save fuel and reduce costs and radiological hazard. Unlike DIPS based on turbomachinery conversion (e.g. Brayton), this small Stirling DIPS can be advantageously scaled to multihundred-watt unit size while preserving size and mass competitiveness with RTG's. Stirling conversion extends the competitive range for dynamic systems down to a few hundred watts--a power level not previously considered for dynamic systems. The challenge for Stirling conversion will be to demonstrate reliability and life similar to RTG experience. Since the competitive potential of FPSE as an isotope converter was first identified, work has focused on feasibility of directly integrating GPHS with the Stirling heater head. Thermal modeling of various radiatively coupled heat source/heater head geometries has been performed using data furnished by the developers of FPSE and GPHS. The analysis indicates that, for the 1050 K heater head configurations considered, GPHS fuel clad temperatures remain within acceptable operating limits. Based on these results, preliminary characterizations of multihundred-watt units have been established

  2. Small Stirling dynamic isotope power system for multihundred-watt robotic missions

    International Nuclear Information System (INIS)

    Bents, D.J.

    1991-01-01

    Free Piston Stirling Engine (FPSE) and linear alternator (LA) technology is combined with radioisotope heat sources to produce a compact dynamic isotope power system (DIPS) suitable for multihundred watt space application which appears competitive with advance radioisotope thermoelectric generators (RTGs). The small Stirling DIPS is scalable to multihundred watt power levels or lower. The FPSE/LA is a high efficiency convertor in sizes ranging from tens of kilowatts down to only a few watts. At multihundred watt unit size, the FPSE can be directly integrated with the General Purpose Heat Source (GPHS) via radiative coupling; the resulting dynamic isotope power system has a size and weight that compares favorably with the advanced modular (Mod) RTG, but requires less than a third the amount of isotope fuel. Thus the FPSE extends the high efficiency advantage of dynamic systems into a power range never previously considered competitive for DIPS. This results in lower fuel cost and reduced radiological hazard per delivered electrical watt. 33 refs

  3. Stirling Engine Dynamic System Modeling

    Science.gov (United States)

    Nakis, Christopher G.

    2004-01-01

    The Thermo-Mechanical systems branch at the Glenn Research Center focuses a large amount time on Stirling engines. These engines will be used on missions where solar power is inefficient, especially in deep space. I work with Tim Regan and Ed Lewandowski who are currently developing and validating a mathematical model for the Stirling engines. This model incorporates all aspects of the system including, mechanical, electrical and thermodynamic components. Modeling is done through Simplorer, a program capable of running simulations of the model. Once created and then proven to be accurate, a model is used for developing new ideas for engine design. My largest specific project involves varying key parameters in the model and quantifying the results. This can all be done relatively trouble-free with the help of Simplorer. Once the model is complete, Simplorer will do all the necessary calculations. The more complicated part of this project is determining which parameters to vary. Finding key parameters depends on the potential for a value to be independently altered in the design. For example, a change in one dimension may lead to a proportional change to the rest of the model, and no real progress is made. Also, the ability for a changed value to have a substantial impact on the outputs of the system is important. Results will be condensed into graphs and tables with the purpose of better communication and understanding of the data. With the changing of these parameters, a more optimal design can be created without having to purchase or build any models. Also, hours and hours of results can be simulated in minutes. In the long run, using mathematical models can save time and money. Along with this project, I have many other smaller assignments throughout the summer. My main goal is to assist in the processes of model development, validation and testing.

  4. Isotope powered Stirling generator for terrestrial applications

    International Nuclear Information System (INIS)

    Tingey, G.L.; Sorensen, G.C.; Ross, B.A.

    1995-01-01

    An electric power supply, small enough to be man-portable, is being developed for remote, terrestrial applications. This system is designed for an operating lifetime of five years without maintenance or refueling. A small Radioisotope Stirling Generator (RSG) has been developed. The energy source of the generator is a 60 watt plutonium-238 fuel clad used in the General Purpose Heat Sources (GPHS) developed for space applications. A free piston Stirling Engine drives a linear alternator to convert the heat to power. The system weighs about 7.5 kg and produces 11 watts AC power with a conversion efficiency of 18.5%. Two engine models have been designed, fabricated, and tested to date: (a) a developmental model instrumented to confirm and test parameters, and (b) an electrically heated model with an electrical heater equipped power input leads. Critical components have been tested for 10,000 to 20,000 hours. One complete generator has been operating for over 11,000 hours. Radioisotope heated prototypes are expected to be fabricated and tested in late 1995

  5. Development of a Stirling System Dynamic Model with Enhanced Thermodynamics

    Science.gov (United States)

    Regan, Timothy F.; Lewandowski, Edward J.

    2005-02-01

    The Stirling Convertor System Dynamic Model developed at NASA Glenn Research Center is a software model developed from first principles that includes the mechanical and mounting dynamics, the thermodynamics, the linear alternator, and the controller of a free-piston Stirling power convertor, along with the end user load. As such it represents the first detailed modeling tool for fully integrated Stirling convertor-based power systems. The thermodynamics of the model were originally a form of the isothermal Stirling cycle. In some situations it may be desirable to improve the accuracy of the Stirling cycle portion of the model. An option under consideration is to enhance the SDM thermodynamics by coupling the model with Gedeon Associates' Sage simulation code. The result will be a model that gives a more accurate prediction of the performance and dynamics of the free-piston Stirling convertor. A method of integrating the Sage simulation code with the System Dynamic Model is described. Results of SDM and Sage simulation are compared to test data. Model parameter estimation and model validation are discussed.

  6. Dynamics of the Ross-Stirling engine

    Energy Technology Data Exchange (ETDEWEB)

    Doige, A G; Walker, G

    1986-01-01

    A computer model has been developed for the simulation of the dynamic loading in a Stirling engine having a Ross linkage as the drive mechanism. The model is based on a complete theoretical formulation of the dynamics of the system. The masses and moments of inertia of all moving components have been included in the model. The computer program can be used for determining the effect of changes in many design parameters on the geometry, velocities, accelerations, dynamic loading and reactions at all pin connections and engine-mount locations. In this paper, emphasis is given to assessing the general characteristics of the reaction forces at the pin connections and to the reduction of overall engine shaking forces by simple balancing methods. The most heavily loaded element in the engine is the pin connecting the crank and the yoke. The force at that location is a combination of a static load produced by gas pressure in the cylinders and a combined inertia load for the whole engine which increases with the square of the rotational speed. 6 refs., 12 figs., 2 tabs.

  7. Dynamic Analysis and Test Results for an STC Stirling Generator

    Science.gov (United States)

    Qiu, Songgang; Peterson, Allen A.

    2004-02-01

    Long-life, high-efficiency generators based on free-piston Stirling machines are a future energy-conversion solution for both space and commercial applications. To aid in design and system integration efforts, Stirling Technology Company (STC) has developed dynamic simulation models for the internal moving subassemblies and for complete Stirling convertor assemblies. These dynamic models have been validated using test data from operating prototypes. Simplified versions of these models are presented to help explain the operating characteristics of the Stirling convertor. Power spectrum analysis is presented for the test data for casing acceleration, piston motion, displacer motion, and controller current/voltage during full power operation. The harmonics of a Stirling convertor and its moving components are identified for the STC zener-diode control scheme. The dynamic behavior of each moving component and its contribution to the system dynamics and resultant vibration forces are discussed. Additionally, the effects of a passive balancer and external suspension are predicted by another simplified system model.

  8. Linear Dynamics and Control of a Kinematic Wobble–Yoke Stirling Engine

    NARCIS (Netherlands)

    Alvarez–Aguirre, Alejandro; García–Canseco, Eloísa; Scherpen, Jacquelien M.A.

    2010-01-01

    This paper presents a control systems approach for the modeling and control of a kinematic wobble–yoke Stirling engine. The linear dynamics of the Stirling engine are analyzed based on the dynamical model of the system, developed by these authors. We show that the Stirling engine can be viewed as a

  9. Linear dynamics and control of a kinematic wobble-yoke Stirling engine

    NARCIS (Netherlands)

    Alvarez Aguirre, A.; Garcia Canseco, E.; Scherpen, J.M.A.

    2010-01-01

    This paper presents a control systems approachfor the modeling and control of a kinematic wobbleyokeStirling engine. The linear dynamics of the Stirling engine are analyzed based on the dynamical model of the system, developed by the authors in [1]. We show that the Stirling engine can be viewed as

  10. Basic dynamics of split Stirling refrigerators

    NARCIS (Netherlands)

    Waele, de A.T.A.M.; Liang, W.

    2008-01-01

    The basic features of the split Stirling refrigerator, driven by a linear compressor, are described. Friction of the compressor piston and of the regenerator, and the viscous losses due to the gas flow through the regenerator matrix are taken into account. The temp. at the cold end is an input

  11. Simulational nanoengineering: Molecular dynamics implementation of an atomistic Stirling engine.

    Science.gov (United States)

    Rapaport, D C

    2009-04-01

    A nanoscale-sized Stirling engine with an atomistic working fluid has been modeled using molecular dynamics simulation. The design includes heat exchangers based on thermostats, pistons attached to a flywheel under load, and a regenerator. Key aspects of the behavior, including the time-dependent flows, are described. The model is shown to be capable of stable operation while producing net work at a moderate level of efficiency.

  12. Multimodal tuned dynamic absorber for split Stirling linear cryocooler

    Science.gov (United States)

    Veprik, A.; Tuito, A.

    2017-02-01

    Forthcoming low size, weight, power and price split Stirling linear cryocoolers may rely on electro-dynamically driven single-piston compressors and pneumatically driven expanders interconnected by the configurable transfer line. For compactness, compressor and expander units may be placed in a side-by-side manner, thus producing tonal vibration export comprising force and moment components. In vibration sensitive applications, this may result in excessive angular line of sight jitter and translational defocusing affecting the image quality. The authors present Multimodal Tuned Dynamic Absorber (MTDA), having one translational and two tilting modes essentially tuned to the driving frequency. The dynamic reactions (force and moment) produced by such a MTDA are simultaneously counterbalancing force and moment vibration export produced by the cryocooler. The authors reveal the design details, the method of fine modal tuning and outcomes of numerical simulation on attainable performance.

  13. Dynamic model of Stirling engine crank mechanism with connected electric generator

    Directory of Open Access Journals (Sweden)

    Vlach R.

    2009-06-01

    Full Text Available This paper treats of a numerical dynamic model of Stirling engine crank mechanism. The model is included in the complex model of combined heat and power unit. The unit is composed of the Stirling engine and of attached three-phase synchronous generator. This generator should start the Stirling engine in motor mode as well. It is necessary to combine the crank shaft dynamic model and the complete thermal model of Stirling engine for simulations and analyses of engine run. Our aim is to create a dynamics model which takes into account the parameters of crankshaft, piston rods, pistons, and attached generator. For unit working, the electro-mechanical behaviour of generator is also important. That is why we experimentally verified the parameters of generator. The measured characteristics are used in a complex model of heat and power unit. Moreover, it is also possible to determine the Stirling engine torque by the help of these electro-mechanical characteristics. These values can be used e. g. for determination of optimal engine working point or for unit control.

  14. Structural Dynamics Testing of Advanced Stirling Convertor Components

    Science.gov (United States)

    Oriti, Salvatore M.; Williams, Zachary Douglas

    2013-01-01

    NASA Glenn Research Center has been supporting the development of Stirling energy conversion for use in space. Lockheed Martin has been contracted by the Department of Energy to design and fabricate flight-unit Advanced Stirling Radioisotope Generators, which utilize Sunpower, Inc., free-piston Advanced Stirling Convertors. The engineering unit generator has demonstrated conversion efficiency in excess of 20 percent, offering a significant improvement over existing radioisotope-fueled power systems. NASA Glenn has been supporting the development of this generator by developing the convertors through a technology development contract with Sunpower, and conducting research and experiments in a multitude of areas, such as high-temperature material properties, organics testing, and convertor-level extended operation. Since the generator must undergo launch, several launch simulation tests have also been performed at the convertor level. The standard test sequence for launch vibration exposure has consisted of workmanship and flight acceptance levels. Together, these exposures simulate what a flight convertor will experience. Recently, two supplementary tests were added to the launch vibration simulation activity. First was a vibration durability test of the convertor, intended to quantify the effect of vibration levels up to qualification level in both the lateral and axial directions. Second was qualification-level vibration of several heater heads with small oxide inclusions in the material. The goal of this test was to ascertain the effect of the inclusions on launch survivability to determine if the heater heads were suitable for flight.

  15. On the dynamic response of pressure transmission lines in the research of helium-charged free piston Stirling engines

    Science.gov (United States)

    Miller, Eric L.; Dudenhoefer, James E.

    1989-01-01

    The signal distortion inherent to pressure transmission lines in free-piston Stirling engine research is discussed. Based on results from classical analysis, guidelines are formulated to describe the dynamic response properties of a volume-terminated transmission tube for applications involving the helium-charged free-piston Stirling engines. The underdamped flow regime is described, the primary resonance frequency is derived, and the pressure phase and amplitude distortion are discussed. The scope and limitation of the dynamic response analysis are considered.

  16. Modeling the dynamic and thermodynamic operation of Stirling engines by means of an equivalent electrical circuit

    International Nuclear Information System (INIS)

    Cascella, Franco; Sorin, Mikhail; Formosa, Fabien; Teyssedou, Alberto

    2017-01-01

    Highlights: • A model based on the electrical analogy theory has been developed to predict the operation of a Stirling engine. • The models takes into account the continuity, the momentum and the energy conservation equations. • The model predicts the operating conditions of the RE100 Free piston Stirling engine. • The model is sensible to the modeling of the effects of the machine load. - Abstract: The Stirling engines are inherently efficient; their thermodynamic cycles reach the Carnot efficiency. These technologies are suitable to operate under any low temperature difference between the hot and the cold sources. For these reasons, these engines can be considered as reliable power conversion systems to promote the conversion of low-grade waste heat generated by industrial plants. The need of a model to predict the behavior of these engines is of primary importance. Nevertheless, a great difficulty is encountered in developing such a model since it is not simple to take into account coupled thermodynamic and dynamic effects. This is the main reason why several models make use of electrical analogies to describe Stirling engines (in particular, free-piston machines): by assuming the pressure equivalent to a voltage and the flow rate to an electrical current, a coupled dynamic-thermodynamic analysis of the engine can be performed. In this paper, an electrical circuit whose behavior is equivalent to that of the engine is derived from the electrical analogy theory. To this aim, we propose an electrical analogy model based on the three conservation laws (mass, momentum and energy). Since limited experimental information is available in the open literature, the results obtained with the proposed model are compared with the experimental data collected at the NASA Lewis Research center for a free-piston Stirling engine i.e., the RE-1000 engine.

  17. A comparison of radioisotope Brayton and Stirling system for lunar surface mobile power

    International Nuclear Information System (INIS)

    Harty, R.B.

    1991-01-01

    A study was performed by the Rocketdyne Division of Rockwell 2.5-kWe modular dynamic isotope power system (DIPS) using a Stirling power conversion system. The results of this study were compared with similar results performed under the DIPS program using a Brayton power conversion system. The study indicated that the Stirling power module has 20% lower mass and 40% lower radiator area than the Brayton module. However, the study also revealed that because the Stirling power module requires a complex heat pipe arrangment to transport heat from the isotope to the Stirling heater head and a pumped NaK heat rejection loop, the Stirling module is much more difficult to integrate with the isotope heat source and heat rejection system

  18. Coupled thermodynamic-dynamic semi-analytical model of free piston Stirling engines

    Energy Technology Data Exchange (ETDEWEB)

    Formosa, F., E-mail: fabien.formosa@univ-savoie.f [Laboratoire SYMME, Universite de Savoie, BP 80439, 74944 Annecy le Vieux Cedex (France)

    2011-05-15

    Research highlights: {yields} The free piston Stirling behaviour relies on its thermal and dynamic features. {yields} A global semi-analytical model for preliminary design is developed. {yields} The model compared with NASA-RE1000 experimental data shows good correlations. -- Abstract: The study of free piston Stirling engine (FPSE) requires both accurate thermodynamic and dynamic modelling to predict its performances. The steady state behaviour of the engine partly relies on non linear dissipative phenomena such as pressure drop loss within heat exchangers which is dependant on the temperature within the associated components. An analytical thermodynamic model which encompasses the effectiveness and the flaws of the heat exchangers and the regenerator has been previously developed and validated. A semi-analytical dynamic model of FPSE is developed and presented in this paper. The thermodynamic model is used to define the thermal variables that are used in the dynamic model which evaluates the kinematic results. Thus, a coupled iterative strategy has been used to perform a global simulation. The global modelling approach has been validated using the experimental data available from the NASA RE-1000 Stirling engine prototype. The resulting coupled thermodynamic-dynamic model using a standardized description of the engine allows efficient and realistic preliminary design of FPSE.

  19. Coupled thermodynamic-dynamic semi-analytical model of free piston Stirling engines

    International Nuclear Information System (INIS)

    Formosa, F.

    2011-01-01

    Research highlights: → The free piston Stirling behaviour relies on its thermal and dynamic features. → A global semi-analytical model for preliminary design is developed. → The model compared with NASA-RE1000 experimental data shows good correlations. -- Abstract: The study of free piston Stirling engine (FPSE) requires both accurate thermodynamic and dynamic modelling to predict its performances. The steady state behaviour of the engine partly relies on non linear dissipative phenomena such as pressure drop loss within heat exchangers which is dependant on the temperature within the associated components. An analytical thermodynamic model which encompasses the effectiveness and the flaws of the heat exchangers and the regenerator has been previously developed and validated. A semi-analytical dynamic model of FPSE is developed and presented in this paper. The thermodynamic model is used to define the thermal variables that are used in the dynamic model which evaluates the kinematic results. Thus, a coupled iterative strategy has been used to perform a global simulation. The global modelling approach has been validated using the experimental data available from the NASA RE-1000 Stirling engine prototype. The resulting coupled thermodynamic-dynamic model using a standardized description of the engine allows efficient and realistic preliminary design of FPSE.

  20. Comparative survey of dynamic analyses of free-piston Stirling engines

    Science.gov (United States)

    Kankam, M. D.; Rauch, J. S.

    1991-01-01

    Reported dynamics analyses for evaluating the steady-state response and stability of free-piston Stirling engine (FPSE) systems are compared. Various analytical approaches are discussed to provide guidance on their salient features. Recommendations are made in the recommendations remarks for an approach which captures most of the inherent properties of the engine. Such an approach has the potential for yielding results which will closely match practical FPSE-load systems.

  1. Nonlinear dynamics analysis of a low-temperature-differential kinematic Stirling heat engine

    Science.gov (United States)

    Izumida, Yuki

    2018-03-01

    The low-temperature-differential (LTD) Stirling heat engine technology constitutes one of the important sustainable energy technologies. The basic question of how the rotational motion of the LTD Stirling heat engine is maintained or lost based on the temperature difference is thus a practically and physically important problem that needs to be clearly understood. Here, we approach this problem by proposing and investigating a minimal nonlinear dynamic model of an LTD kinematic Stirling heat engine. Our model is described as a driven nonlinear pendulum where the motive force is the temperature difference. The rotational state and the stationary state of the engine are described as a stable limit cycle and a stable fixed point of the dynamical equations, respectively. These two states coexist under a sufficient temperature difference, whereas the stable limit cycle does not exist under a temperature difference that is too small. Using a nonlinear bifurcation analysis, we show that the disappearance of the stable limit cycle occurs via a homoclinic bifurcation, with the temperature difference being the bifurcation parameter.

  2. Incorporating Vibration Test Results for the Advanced Stirling Convertor into the System Dynamic Model

    Science.gov (United States)

    Meer, David W.; Lewandowski, Edward J.

    2010-01-01

    The U.S. Department of Energy (DOE), Lockheed Martin Corporation (LM), and NASA Glenn Research Center (GRC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. As part of the extended operation testing of this power system, the Advanced Stirling Convertors (ASC) at NASA GRC undergo a vibration test sequence intended to simulate the vibration history that an ASC would experience when used in an ASRG for a space mission. During these tests, a data system collects several performance-related parameters from the convertor under test for health monitoring and analysis. Recently, an additional sensor recorded the slip table position during vibration testing to qualification level. The System Dynamic Model (SDM) integrates Stirling cycle thermodynamics, heat flow, mechanical mass, spring, damper systems, and electrical characteristics of the linear alternator and controller. This Paper presents a comparison of the performance of the ASC when exposed to vibration to that predicted by the SDM when exposed to the same vibration.

  3. On the dynamical vs. thermodynamical performance of a β-type Stirling engine

    Science.gov (United States)

    Reséndiz-Antonio, Margarita; Santillán, Moisés

    2014-09-01

    In this work we present a simple mathematical model for a β-type Stirling engine. Despite its simplicity, the model considers all the engine’s relevant thermodynamic and mechanical aspects. The dynamic behavior of the model equation of motion is analyzed in order to obtain the sufficient conditions for engine cycling and to study the stability of the stationary regime. The performance of the engine’s thermodynamic part is also investigated. As a matter of fact, we found that it corresponds to a Carnot engine.

  4. Controllability of Free-piston Stirling Engine/linear Alternator Driving a Dynamic Load

    Science.gov (United States)

    Kankam, M. David; Rauch, Jeffrey S.

    1994-01-01

    This paper presents the dynamic behavior of a Free-Piston Stirling Engine/linear alternator (FPSE/LA) driving a single-phase fractional horse-power induction motor. The controllability and dynamic stability of the system are discussed by means of sensitivity effects of variations in system parameters, engine controller, operating conditions, and mechanical loading on the induction motor. The approach used expands on a combined mechanical and thermodynamic formulation employed in a previous paper. The application of state-space technique and frequency domain analysis enhances understanding of the dynamic interactions. Engine-alternator parametric sensitivity studies, similar to those of the previous paper, are summarized. Detailed discussions are provided for parametric variations which relate to the engine controller and system operating conditions. The results suggest that the controllability of a FPSE-based power system is enhanced by proper operating conditions and built-in controls.

  5. Development of a Dynamic, End-to-End Free Piston Stirling Convertor Model

    Science.gov (United States)

    Regan, Timothy F.; Gerber, Scott S.; Roth, Mary Ellen

    2003-01-01

    A dynamic model for a free-piston Stirling convertor is being developed at the NASA Glenn Research Center. The model is an end-to-end system model that includes the cycle thermodynamics, the dynamics, and electrical aspects of the system. The subsystems of interest are the heat source, the springs, the moving masses, the linear alternator, the controller and the end-user load. The envisioned use of the model will be in evaluating how changes in a subsystem could affect the operation of the convertor. The model under development will speed the evaluation of improvements to a subsystem and aid in determining areas in which most significant improvements may be found. One of the first uses of the end-to-end model will be in the development of controller architectures. Another related area is in evaluating changes to details in the linear alternator.

  6. Stirling Refrigerator

    Science.gov (United States)

    Kagawa, Noboru

    A Stirling cooler (refrigerator) was proposed in 1862 and the first Stirling cooler was put on market in 1955. Since then, many Stirling coolers have been developed and marketed as cryocoolers. Recently, Stirling cycle machines for heating and cooling at near-ambient temperatures between 173 and 400K, are recognized as promising candidates for alternative system which are more compatible with people and the Earth. The ideal cycles of Stirling cycle machine offer the highest thermal efficiencies and the working fluids do not cause serious environmental problems of ozone depletion and global warming. In this review, the basic thermodynamics of Stirling cycle are briefly described to quantify the attractive cycle performance. The fundamentals to realize actual Stirling coolers and heat pumps are introduced in detail. The current status of the Stirling cycle machine technologies is reviewed. Some machines have almost achieved the target performance. Also, duplex-Stirling-cycle and Vuilleumier-cycle machines and their performance are introduced.

  7. Dynamical symmetry breaking in barium isotopes

    International Nuclear Information System (INIS)

    Rawat, Bir Singh; Chattopadhyay, P.K.

    1997-01-01

    The isotopes of Xe with mass numbers 124, 126, 128, 130 and the isotopes of barium with mass numbers 128, 130, 132, 134 were shown to correspond to the O(6) dynamical symmetry of IBM. In the investigation of the dynamical symmetry breaking in this region, the barium isotopes for departures from O(6) symmetry have been studied

  8. Modular Stirling Radioisotope Generator

    Science.gov (United States)

    Schmitz, Paul C.; Mason, Lee S.; Schifer, Nicholas A.

    2016-01-01

    High-efficiency radioisotope power generators will play an important role in future NASA space exploration missions. Stirling Radioisotope Generators (SRGs) have been identified as a candidate generator technology capable of providing mission designers with an efficient, high-specific-power electrical generator. SRGs high conversion efficiency has the potential to extend the limited Pu-238 supply when compared with current Radioisotope Thermoelectric Generators (RTGs). Due to budgetary constraints, the Advanced Stirling Radioisotope Generator (ASRG) was canceled in the fall of 2013. Over the past year a joint study by NASA and the Department of Energy (DOE) called the Nuclear Power Assessment Study (NPAS) recommended that Stirling technologies continue to be explored. During the mission studies of the NPAS, spare SRGs were sometimes required to meet mission power system reliability requirements. This led to an additional mass penalty and increased isotope consumption levied on certain SRG-based missions. In an attempt to remove the spare power system, a new generator architecture is considered, which could increase the reliability of a Stirling generator and provide a more fault-tolerant power system. This new generator called the Modular Stirling Radioisotope Generator (MSRG) employs multiple parallel Stirling convertor/controller strings, all of which share the heat from the General Purpose Heat Source (GPHS) modules. For this design, generators utilizing one to eight GPHS modules were analyzed, which provided about 50 to 450 W of direct current (DC) to the spacecraft, respectively. Four Stirling convertors are arranged around each GPHS module resulting in from 4 to 32 Stirling/controller strings. The convertors are balanced either individually or in pairs, and are radiatively coupled to the GPHS modules. Heat is rejected through the housing/radiator, which is similar in construction to the ASRG. Mass and power analysis for these systems indicate that specific

  9. Comparison of dynamic isotope power systems for distributed planet surface applications

    Science.gov (United States)

    Bents, David J.; Mckissock, Barbara I.; Hanlon, James C.; Schmitz, Paul C.; Rodriguez, Carlos D.; Withrow, Colleen A.

    1991-01-01

    Dynamic isotope power system (DIPS) alternatives were investigated and characterized for the surface mission elements associated with a lunar base and subsequent manned Mars expedition. System designs based on two convertor types were studied. These systems were characterized parametrically and compared over the steady-state electrical output power range 0.2 to 20 kWe. Three methods of thermally integrating the heat source and the Stirling heater head were considered, depending on unit size. Figures of merit were derived from the characterizations and compared over the parametric range. Design impacts of mission environmental factors are discussed and quantitatively assessed.

  10. Stirling converters for space dynamic power concepts with 2 to 130 We output

    International Nuclear Information System (INIS)

    Ross, B.A.

    1995-01-01

    Three innovative Stirling converter concepts are described. Two concepts are based on Pluto Fast Flyby (PFF) mission requirements, where two General Purpose Heat Source (GPHS) modules provide the thermal input. The first concept (PFF2) considers a power system with two opposed Stirling converters; the second concept (PFF4) considers four opposed Stirling converters. For both concepts the Stirling converters are designed to vary their power production capability to compensate for the failure of one Stirling converter. While the net thermal efficiency of PFF4 is a few percentage points lower than PFF2, the total Stirling converter mass of PFF4 is half that for PFF2. The third concept (ITTI) is designed to supply 2 watts of power for weather stations on the Martian surface. The predicted thermal performance of the ITTI is low compared to PFF2 and PFF4, yet the ITTI concept offers significant advantages compared to currently available power systems at the 2-watt power level. All three concepts are based on long-life technology demonstrated by an 11-watt output Stirling generator that as of March 1995 has accumulated over 15,000 operating hours without maintenance

  11. Computation techniques and computer programs to analyze Stirling cycle engines using characteristic dynamic energy equations

    Science.gov (United States)

    Larson, V. H.

    1982-01-01

    The basic equations that are used to describe the physical phenomena in a Stirling cycle engine are the general energy equations and equations for the conservation of mass and conversion of momentum. These equations, together with the equation of state, an analytical expression for the gas velocity, and an equation for mesh temperature are used in this computer study of Stirling cycle characteristics. The partial differential equations describing the physical phenomena that occurs in a Stirling cycle engine are of the hyperbolic type. The hyperbolic equations have real characteristic lines. By utilizing appropriate points along these curved lines the partial differential equations can be reduced to ordinary differential equations. These equations are solved numerically using a fourth-fifth order Runge-Kutta integration technique.

  12. Energy-state formulation of lumped volume dynamic equations with application to a simplified free piston Stirling engine

    Science.gov (United States)

    Daniele, C. J.; Lorenzo, C. F.

    1979-01-01

    Lumped volume dynamic equations are derived using an energy-state formulation. This technique requires that kinetic and potential energy state functions be written for the physical system being investigated. To account for losses in the system, a Rayleigh dissipation function is also formed. Using these functions, a Lagrangian is formed and using Lagrange's equation, the equations of motion for the system are derived. The results of the application of this technique to a lumped volume are used to derive a model for the free-piston Stirling engine. The model was simplified and programmed on an analog computer. Results are given comparing the model response with experimental data.

  13. Stirling Engine Controller

    Science.gov (United States)

    Blaze, Gina M.

    2004-01-01

    and also safely shutdown the engines. The test will last for a period of 8000 to 9000 hours. Other types of tests that have been performed are: performance mapping, controller development, launch environment, and vibration emissions testing. Currently, the thermo-mechanical system branch is housing a RG-350, a stirling convertor. The convertor was used in previous tests such as a Hall Thruster test, world s first integrated test of a dynamic power system with electric propulsion. Another test performed was to conclude if free piston stirling convertors can be synchronized for vibration balancing, with no thermodynamic or electrical connections and not cause both to shutdown if one failed. The ability to reduce vibration by synchronizing convertor operation but still be able to operate when one partner fails is pertinent in space and terrestrial applications. The convertor is now being brought back into operation and a controller is in the process of being developed. This convertor will be used as a testbed for new controllers. I worked with Mary Ellen Roth on the electric engineering aspects of the RG-350. My main goal was to enhance the data collection process. I worked on different aspects of the RG-350, with a main focus on the engine controller. I drew a schematic of the wire connections in the engine controller, using PCB Express, so that a plan could be devised to connect the power meter properly between the output of the engine and the engine controller. I measured the power using two different instruments: Valhalla Scientific power meter and Ohio Semitronics power measurement device. The convertor is connected to an Agilent 34970A Data Acquisition/Switch Unit, which allows the user to measure, record, and monitor voltage, current, frequency, and temperature. I assisted in preparing the Data Acquisition for general operation. I also helped test a panel of transducers, which will be placed in the rack that powers and monitors the convertor.

  14. Heat Transfer and Fluid Dynamics Measurements in the Expansion Space of a Stirling Cycle Engine

    Science.gov (United States)

    Jiang, Nan; Simon, Terrence W.

    2006-01-01

    The heater (or acceptor) of a Stirling engine, where most of the thermal energy is accepted into the engine by heat transfer, is the hottest part of the engine. Almost as hot is the adjacent expansion space of the engine. In the expansion space, the flow is oscillatory, impinging on a two-dimensional concavely-curved surface. Knowing the heat transfer on the inside surface of the engine head is critical to the engine design for efficiency and reliability. However, the flow in this region is not well understood and support is required to develop the CFD codes needed to design modern Stirling engines of high efficiency and power output. The present project is to experimentally investigate the flow and heat transfer in the heater head region. Flow fields and heat transfer coefficients are measured to characterize the oscillatory flow as well as to supply experimental validation for the CFD Stirling engine design codes. Presented also is a discussion of how these results might be used for heater head and acceptor region design calculations.

  15. Dynamic analysis of Free-Piston Stirling Engine/Linear Alternator-load system-experimentally validated

    Science.gov (United States)

    Kankam, M. David; Rauch, Jeffrey S.; Santiago, Walter

    1992-01-01

    This paper discusses the effects of variations in system parameters on the dynamic behavior of the Free-Piston Stirling Engine/Linear Alternator (FPSE/LA)-load system. The mathematical formulations incorporate both the mechanical and thermodynamic properties of the FPSE, as well as the electrical equations of the connected load. A state-space technique in the frequency domain is applied to the resulting system of equations to facilitate the evaluation of parametric impacts on the system dynamic stability. Also included is a discussion on the system transient stability as affected by sudden changes in some key operating conditions. Some representative results are correlated with experimental data to verify the model and analytic formulation accuracies. Guidelines are given for ranges of the system parameters which will ensure an overall stable operation.

  16. Dynamic simulation of hydrogen isotope distillation unit

    International Nuclear Information System (INIS)

    Le Lann, J.M.; Latge, C.; Joulia, X.; Sere-Peyrigain, P.

    1995-01-01

    Dynamic simulation of hydrogen isotope distillation unit involved in the complex environment of a fusion power plant can be a powerful technique in view to analyze the tritium hazard potential. In this paper, issues related to the development of such a dynamic simulator with model formulation and the numerical treatment of the resulting Differential-Algebraic equation (DAE) system are properly adressed. The typical dynamic characteristics of such columns are quantitatively and qualitatively enlighted on case study with very large disturbances. The developed system has proven to be beneficial for understanding the dynamic behaviour and further for developing control schemes. (orig.)

  17. Dynamic simulation of hydrogen isotope distillation unit

    International Nuclear Information System (INIS)

    Le Lann, J.M.; Joulia, X.; Sere-Peyrigain, P.

    1994-01-01

    Dynamic simulation of hydrogen isotope distillation unit involved in the complex environment of a fusion power plant can be a powerful technique in view to analyze the tritium hazard potential. Issues related to the development of such a dynamic simulator with model formulation and the numerical treatment of the resulting Differential-Algebraic equation (DAE) system are properly addressed. The typical dynamic characteristics of such columns are quantitatively and qualitatively enlightened on case study with very large disturbances. The developed system has proven to be beneficial for understanding the dynamic behaviour and further for developing control schemes. (author) 12 refs.; 4 figs

  18. IECEC '91; Proceedings of the 26th Intersociety Energy Conversion Engineering Conference, Boston, MA, Aug. 4-9, 1991. Vol. 5 - Renewable resource systems, Stirling engines and applications, systems and cycles

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    Various papers on energy conversion engineering are presented. The general topics considered are: developments in nuclear power, energy from waste and biomass, system performance and materials in photovoltaics, solar thermal energy, wind energy systems, Stirling cycle analysis, Stirling cycle power, Stirling component technology, Stirling cooler/heat pump developments, Stirling engine concepts, Stirling engine design and optimization, Stirling engine dynamics and response, Stirling engine solar terrestrial, advanced cogeneration, AMTC, fossil fuel systems and technologies, marine energy

  19. Dynamically balanced, hydraulically driven compressor/pump apparatus for resonant free piston Stirling engines

    Science.gov (United States)

    Corey, John A.

    1984-05-29

    A compressor, pump, or alternator apparatus is designed for use with a resonant free piston Stirling engine so as to isolate apparatus fluid from the periodically pressurized working fluid of the Stirling engine. The apparatus housing has a first side closed by a power coupling flexible diaphragm (the engine working member) and a second side closed by a flexible diaphragm gas spring. A reciprocally movable piston is disposed in a transverse cylinder in the housing and moves substantially at right angles relative to the flexible diaphragms. An incompressible fluid fills the housing which is divided into two separate chambers by suitable ports. One chamber provides fluid coupling between the power diaphragm of the RFPSE and the piston and the second chamber provides fluid coupling between the gas spring diaphragm and the opposite side of the piston. The working members of a gas compressor, pump, or alternator are driven by the piston. Sealing and wearing parts of the apparatus are mounted at the external ends of the transverse cylinder in a double acting arrangement for accessibility. An annular counterweight is mounted externally of the reciprocally movable piston and is driven by incompressible fluid coupling in a direction opposite to the piston so as to damp out transverse vibrations.

  20. Stirling co-generation plants - Is this the future?; Stirling-BHKWs - Zukunft oder...?

    Energy Technology Data Exchange (ETDEWEB)

    Seifert, M.

    2000-07-01

    This article gives an overview of the history and main features of Stirling engines and their use in combined-cycle power generation. The principles behind the Stirling and its thermo-dynamic characteristics are discussed and compared with the internal combustion engine and other thermally-driven machines. The two main types of Stirling - the free-piston and the kinematic Stirling engines are discussed. Also, the important role played by the burner in the operation of Stirling engines is discussed. The use of Stirling engines as a basis for small combined heat and power (CHP) units to produce thermal heating power and electricity is examined. Three examples - the implementations made by the Solo, Whispergen and SIG companies - are looked at in detail and compared with alternative CHP-solutions using small gas engines and fuel cells. The advantages and disadvantages of these different solutions are listed.

  1. Dynamic isotope studies in liver disease

    Energy Technology Data Exchange (ETDEWEB)

    Weits, J

    1978-01-01

    Much information in the field of liver research has been gained by dynamic isotope studies. Clinically, these studies can help to settle selection criteria for different types of surgical shunt, which relieve the complications of portal hypertension. By performing splenoportoscintigraphy, splenic and portal vein thrombosis can be easily and safely excluded. So-called hypoxaemia of cirrhosis can most easily be diagnosed. Suprahepatic caval vein obstruction in a patient with cryptogenic liver disease is easily excluded by a radionuclide cavogram after injection of pertechnetate into a foot vein.

  2. Brayton dynamic isotope power systems update

    International Nuclear Information System (INIS)

    Davis, K.A.; Pietsch, A.; Casagrande, R.D.

    1986-01-01

    Brayton dynamic power systems are uniquely suited for space applications. They are compact and highly efficient, offer inherent reliability due to only one moving part, and utilize a single phase and inert working fluid. Additional features include gas bearings, constant speed, and operation at essentially constant temperature. The design, utilizing an inert gas working fluid and gas bearing, is unaffected by zero gravity and can be easily started and restarted in space at low temperatures. This paper describes the salient features of the BIPS as a Dynamic Isotope Power System (DIPS), summarizes the development work to date, establishes the maturity of the design, provides an update on materials technology, and reviews systems integration considerations

  3. Dynamic simulation of a beta-type Stirling engine with cam-drive mechanism via the combination of the thermodynamic and dynamic models

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Chin-Hsiang; Yu, Ying-Ju [Department of Aeronautics and Astronautics, National Cheng Kung University, No. 1, Ta-Shieh Road, Tainan, Taiwan (China)

    2011-02-15

    Dynamic simulation of a beta-type Stirling engine with cam-drive mechanism used in concentrating solar power system has been performed. A dynamic model of the mechanism is developed and then incorporated with the thermodynamic model so as to predict the transient behavior of the engine in the hot-start period. In this study, the engine is started from an initial rotational speed. The torques exerted by the flywheel of the engine at any time instant can be calculated by the dynamic model as long as the gas pressures in the chambers, the mass inertia, the friction force, and the external load have been evaluated. The instantaneous rotation speed of the engine is then determined by integration of the equation of rotational motion with respect to time, which in return affects the instantaneous variations in pressure and other thermodynamic properties of the gas inside the chambers. Therefore, the transient variations in gas properties inside the engine chambers and the dynamic behavior of the engine mechanism should be handled simultaneously via the coupling of the thermodynamic and dynamic models. An extensive parametric study of the effects of different operating and geometrical parameters has been performed, and results regarding the effects of mass moment of inertia of the flywheel, initial rotational speed, initial charged pressure, heat source temperature, phase angle, gap size, displacer length, and piston stroke on the engine transient behavior are investigated. (author)

  4. Exploring the isotopic niche: isotopic variance, physiological incorporation, and the temporal dynamics of foraging

    Directory of Open Access Journals (Sweden)

    Justin Douglas Yeakel

    2016-01-01

    Full Text Available Consumer foraging behaviors are dynamic, changing in response to prey availability, seasonality, competition, and even the consumer's physiological state. The isotopic composition of a consumer is a product of these factors as well as the isotopic `landscape' of its prey, i.e. the isotopic mixing space. Stable isotope mixing models are used to back-calculate the most likely proportional contribution of a set of prey to a consumer's diet based on their respective isotopic distributions, however they are disconnected from ecological process. Here we build a mechanistic framework that links the ecological and physiological processes of an individual consumer to the isotopic distribution that describes its diet, and ultimately to the isotopic composition of its own tissues, defined as its `isotopic niche’. By coupling these processes, we systematically investigate under what conditions the isotopic niche of a consumer changes as a function of both the geometric properties of its mixing space and foraging strategies that may be static or dynamic over time. Results of our derivations reveal general insight into the conditions impacting isotopic niche width as a function of consumer specialization on prey, as well as the consumer's ability to transition between diets over time. We show analytically that moderate specialization on isotopically unique prey can serve to maximize a consumer's isotopic niche width, while temporally dynamic diets will tend to result in peak isotopic variance during dietary transitions. We demonstrate the relevance of our theoretical findings by examining a marine system composed of nine invertebrate species commonly consumed by sea otters. In general, our analytical framework highlights the complex interplay of mixing space geometry and consumer dietary behavior in driving expansion and contraction of the isotopic niche. Because this approach is established on ecological mechanism, it is well-suited for enhancing the

  5. Advanced Stirling Radioisotope Generator Life Certification Plan

    Science.gov (United States)

    Rusick, Jeffrey J.; Zampino, Edward J.

    2013-01-01

    An Advanced Stirling Radioisotope Generator (ASRG) power supply is being developed by the Department of Energy (DOE) in partnership with NASA for potential future deep space science missions. Unlike previous radioisotope power supplies for space exploration, such as the passive MMRTG used recently on the Mars Curiosity rover, the ASRG is an active dynamic power supply with moving Stirling engine mechanical components. Due to the long life requirement of 17 years and the dynamic nature of the Stirling engine, the ASRG project faced some unique challenges trying to establish full confidence that the power supply will function reliably over the mission life. These unique challenges resulted in the development of an overall life certification plan that emphasizes long-term Stirling engine test and inspection when analysis is not practical. The ASRG life certification plan developed is described.

  6. Demonstration of a free piston Stirling engine driven linear alternator, phase I report

    International Nuclear Information System (INIS)

    Goldwater, B.; Piller, S.; Rauch, J.; Cella, A.

    1977-01-01

    The results of the work performed under Phase I of the free piston Stirling engine demonstrator program are described. The objective of the program is to develop a 2 kW free piston Stirling engine/linear alternator energy conversion system, for an isotopic heat source, with a greater than 30% overall efficiency. Phase I was a 15-month effort to demonstrate the feasibility of the system through analysis and experimental testing of the individual components. An introduction to Stirling engines and the details of the tasks completed are presented in five major sections: (1) introduction to Stirling engine; (2) preliminary design of an advanced free piston Stirling demonstrator engine; (3) design and test of a 1 kWE output linear alternator; (4) test of a model free piston Stirling engine; and (5) development of a free piston Stirling engine computer simulation code

  7. Demonstration of a free piston Stirling engine driven linear alternator, phase I report

    Energy Technology Data Exchange (ETDEWEB)

    Goldwater, B.; Piller, S.; Rauch, J.; Cella, A.

    1977-03-30

    The results of the work performed under Phase I of the free piston Stirling engine demonstrator program are described. The objective of the program is to develop a 2 kW free piston Stirling engine/linear alternator energy conversion system, for an isotopic heat source, with a greater than 30% overall efficiency. Phase I was a 15-month effort to demonstrate the feasibility of the system through analysis and experimental testing of the individual components. An introduction to Stirling engines and the details of the tasks completed are presented in five major sections: (1) introduction to Stirling engine; (2) preliminary design of an advanced free piston Stirling demonstrator engine; (3) design and test of a 1 kWE output linear alternator; (4) test of a model free piston Stirling engine; and (5) development of a free piston Stirling engine computer simulation code.

  8. Modeling for Control of a Wobble–Yoke Stirling Engine

    NARCIS (Netherlands)

    García–Canseco, Eloísa; Scherpen, Jacquelien M.A.; Kuindersma, Marnix

    2009-01-01

    In this paper we derive the dynamic model of a four–cylinder double–acting wobble–yoke Stirling engine. In contrast with the classical thermodynamics methods that dominate the literature of Stirling mechanisms, we present a control system perspective to obtain a useful model for the analysis and

  9. Modeling for Control of a Wobble-Yoke Stirling Engine

    NARCIS (Netherlands)

    Garcia Canseco, E.; Scherpen, J.M.A.; Kuindersma, M.

    2009-01-01

    In this paper we derive the dynamical model of a four–cylinder double–acting wobble–yoke Stirling engine introduced originally by [1, 2]. In contrast with the classical thermodynamics methods that dominate the literature of Stirling mechanisms, we present a control systems perspective to obtain a

  10. Stirling Engine Cycle Efficiency

    OpenAIRE

    Naddaf, Nasrollah

    2012-01-01

    ABSTRACT This study strives to provide a clear explanation of the Stirling engine and its efficiency using new automation technology and the Lab View software. This heat engine was invented by Stirling, a Scottish in 1918. The engine’s working principles are based on the laws of thermodynamics and ability of volume expansion of ideal gases at different temperatures. Basically there are three types of Stirling engines: the gamma, beta and alpha models. The commissioner of the thesis ...

  11. Stirling Engine Gets Revisited

    Science.gov (United States)

    Thompson, Frank

    2010-01-01

    One of the basic truths regarding energy conversion is that no thermodynamic cycle can be devised that is more efficient than a Carnot cycle operating between the same temperature limits. The efficiency of the Stirling cycle (patented by Rev. Robert Stirling in 1816) can approach that of the Carnot cycle and yet has not had the commercial success…

  12. European Stirling forum 2000. Proceedings; Europaeisches Stirling Forum 2000. Tagungsband

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    This document comprises all 42 papers presented at the 'European Stirling Forum 2000', held in Osnabrueck on February 22-24, 2000. Among others, the following subjects were discussed: Thermodynamics, new developments, Stirling engines, free piston heat pumps, flow optimisation of regenerators for Stirling engines, simulation for modelling of flow and heat transfer in the gas cycle of Stirling engines, design and performance, Stirling refrigerators, economic efficiency of biomass Stirling engines, power control of a Stirling CHP system, a Stirling refrigerator for ultralow temperatures in the refrigeration industry. [German] Das vorliegende Dokument enthaelt alle (42) Beitraege der Referenten des 'Europaeischen Stirling Forums 2000', das vom 22. bis 24. Februar 2000 in Osnabrueck stattgefunden hat. Einige der behandelten Themenschwerpunkte im Zusammenhang mit der Stirling-Maschine waren die Thermodynamik, neue Entwicklungen des Kreisprozesses, Heissgasmotoren, Freikolben-Waermepumpe, stroemungstechnische Optimierung von Regeneratoren fuer Stirling-Maschinen, Simulation zur Modellierung der Stroemung und Waermeuebertragung im Gaskreislauf von Stirling-Maschinen, Entwurf und Betriebsverhalten, Stirling-Kaeltemaschine, Wirtschaftlichkeit von Biomasse-Stirlingmotoren, Leistungsregelung eines Stirling-Blockheizkraftwerks, Anwendung eines Stirling-Kuehlers, zum Ultratiefkuehlen in der Kuehlindustrie. (AKF)

  13. Maturing Technologies for Stirling Space Power Generation

    Science.gov (United States)

    Wilson, Scott D.; Nowlin, Brentley C.; Dobbs, Michael W.; Schmitz, Paul C.; Huth, James

    2016-01-01

    Stirling Radioisotope Power Systems (RPS) are being developed as an option to provide power on future space science missions where robotic spacecraft will orbit, flyby, land or rove. A Stirling Radioisotope Generator (SRG) could offer space missions a more efficient power system that uses one fourth of the nuclear fuel and decreases the thermal footprint of the current state of the art. The RPS Program Office, working in collaboration with the U.S. Department of Energy (DOE), manages projects to develop thermoelectric and dynamic power systems, including Stirling Radioisotope Generators (SRGs). The Stirling Cycle Technology Development (SCTD) Project, located at Glenn Research Center (GRC), is developing Stirling-based subsystems, including convertors and controllers. The SCTD Project also performs research that focuses on a wide variety of objectives, including increasing convertor temperature capability to enable new environments, improving system reliability or fault tolerance, reducing mass or size, and developing advanced concepts that are mission enabling. Research activity includes maturing subsystems, assemblies, and components to prepare them for infusion into future convertor and generator designs. The status of several technology development efforts are described here. As part of the maturation process, technologies are assessed for readiness in higher-level subsystems. To assess the readiness level of the Dual Convertor Controller (DCC), a Technology Readiness Assessment (TRA) was performed and the process and results are shown. Stirling technology research is being performed by the SCTD Project for NASA's RPS Program Office, where tasks focus on maturation of Stirling-based systems and subsystems for future space science missions.

  14. Molecular dynamics simulation of hydrogen isotope injection into graphene

    International Nuclear Information System (INIS)

    Nakamura, Hiroaki; Takayama, Arimichi; Ito, Atsushi

    2007-07-01

    We reveal the hydrogen isotope effect of three chemical reactions, i.e., the reflection, the absorption and the penetration ratios, by classical molecular dynamics simulation with a modified Brenner's reactive empirical bond order (REBO) potential. We find that the reflection by π-electron does not depend on the mass of the incident isotope, but the peak of the reflection by nuclear moves to higher side of incident energy. In addition to the reflection, we also find that the absorption ratio in the positive z side of the graphene becomes larger, as the mass of the incident isotope becomes larger. On the other hand, the absorption ratio in the negative z side of the graphene becomes smaller. Last, it is found that the penetration ratio does not depend on the mass of the incident isotope because the graphene potential is not affected by the mass. (author)

  15. Stirling Technology Development at NASA GRC

    Science.gov (United States)

    Thieme, Lanny G.; Schreiber, Jeffrey G.; Mason, Lee S.

    2001-01-01

    The Department of Energy, Stirling Technology Company (STC), and NASA Glenn Research Center (NASA Glenn) are developing a free-piston Stirling convertor for a high efficiency Stirling Radioisotope Generator (SRG) for NASA Space Science missions. The SRG is being developed for multimission use, including providing electric power for unmanned Mars rovers and deep space missions. NASA Glenn is conducting an in-house technology project to assist in developing the convertor for space qualification and mission implementation. Recent testing of 55-We Technology Demonstration Convertors (TDCs) built by STC includes mapping of a second pair of TDCs, single TDC testing, and TDC electromagnetic interference and electromagnetic compatibility characterization on a nonmagnetic test stand. Launch environment tests of a single TDC without its pressure vessel to better understand the convertor internal structural dynamics and of dual-opposed TDCs with several engineering mounting structures with different natural frequencies have recently been completed. A preliminary life assessment has been completed for the TDC heater head, and creep testing of the IN718 material to be used for the flight convertors is underway. Long-term magnet aging tests are continuing to characterize any potential aging in the strength or demagnetization resistance of the magnets used in the linear alternator (LA). Evaluations are now beginning on key organic materials used in the LA and piston/rod surface coatings. NASA Glenn is also conducting finite element analyses for the LA, in part to look at the demagnetization margin on the permanent magnets. The world's first known integrated test of a dynamic power system with electric propulsion was achieved at NASA Glenn when a Hall-effect thruster was successfully operated with a free-piston Stirling power source. Cleveland State University is developing a multidimensional Stirling computational fluid dynamics code to significantly improve Stirling loss

  16. Stirling Technology Development at NASA GRC. Revised

    Science.gov (United States)

    Thieme, Lanny G.; Schreiber, Jeffrey G.; Mason, Lee S.

    2002-01-01

    The Department of Energy, Stirling Technology Company (STC), and NASA Glenn Research Center (NASA Glenn) are developing a free-piston Stirling convertor for a high-efficiency Stirling Radioisotope Generator (SRG) for NASA Space Science missions. The SRG is being developed for multimission use, including providing electric power for unmanned Mars rovers and deep space missions. NASA Glenn is conducting an in-house technology project to assist in developing the convertor for space qualification and mission implementation. Recent testing, of 55-We Technology Demonstration Convertors (TDC's) built by STC includes mapping, of a second pair of TDC's, single TDC testing, and TDC electromagnetic interference and electromagnetic compatibility characterization on a nonmagnetic test stand. Launch environment tests of a single TDC without its pressure vessel to better understand the convertor internal structural dynamics and of dual-opposed TDC's with several engineering mounting structures with different natural frequencies have recently been completed. A preliminary life assessment has been completed for the TDC heater head, and creep testing of the IN718 material to be used for the flight convertors is underway. Long-term magnet aging tests are continuing to characterize any potential aging in the strength or demagnetization resistance of the magnets used in the linear alternator (LA). Evaluations are now beginning on key organic materials used in the LA and piston/rod surface coatings. NASA Glenn is also conducting finite element analyses for the LA, in part to look at the demagnetization margin on the permanent magnets. The world's first known integrated test of a dynamic power system with electric propulsion was achieved at NASA Glenn when a Hall-effect thruster was successfully operated with a free-piston Stirling power source. Cleveland State University is developing a multidimensional Stirling computational fluid dynamics code to significantly improve Stirling loss

  17. Stirling technology development at NASA GRC

    Science.gov (United States)

    Thieme, Lanny G.; Schreiber, Jeffrey G.; Mason, Lee S.

    2002-01-01

    The Department of Energy, Stirling Technology Company (STC), and NASA Glenn Research Center (GRC) are developing a free-piston Stirling convertor for a high-efficiency Stirling Radioisotope Generator (SRG) for NASA Space Science missions. The SRG is being developed for multimission use, including providing electric power for unmanned Mars rovers and deep space missions. NASA GRC is conducting an in-house technology project to assist in developing the convertor for space qualification and mission implementation. Recent testing of 55-We Technology Demonstration Convertors (TDC's) built by STC includes mapping of a second pair of TDC's, single TDC testing, and TDC electromagnetic interference and electromagnetic compatibility characterization on a non-magnetic test stand. Launch environment tests of a single TDC without its pressure vessel to better understand the convertor internal structural dynamics and of dual-opposed TDC's with several engineering mounting structures with different natural frequencies have recently been completed. A preliminary life assessment has been completed for the TDC heater head, and creep testing of the IN718 material to be used for the flight convertors is underway. Long-term magnet aging tests are continuing to characterize any potential aging in the strength or demagnetization resistance of the magnets used in the linear alternator (LA). Evaluations are now beginning on key organic materials used in the LA and piston/rod surface coatings. GRC is also conducting finite element analyses for the LA, in part to look at the demagnetization margin on the permanent magnets. The world's first known integrated test of a dynamic power system with electric propulsion was achieved at GRC when a Hall-effect thruster was successfully operated with a free-piston Stirling power source. Cleveland State University is developing a multi-dimensional Stirling computational fluid dynamics code to significantly improve Stirling loss predictions and assist in

  18. Fast Whole-Engine Stirling Analysis

    Science.gov (United States)

    Dyson, Rodger W.; Wilson, Scott D.; Tew, Roy C.; Demko, Rikako

    2007-01-01

    An experimentally validated approach is described for fast axisymmetric Stirling engine simulations. These simulations include the entire displacer interior and demonstrate it is possible to model a complete engine cycle in less than an hour. The focus of this effort was to demonstrate it is possible to produce useful Stirling engine performance results in a time-frame short enough to impact design decisions. The combination of utilizing the latest 64-bit Opteron computer processors, fiber-optical Myrinet communications, dynamic meshing, and across zone partitioning has enabled solution times at least 240 times faster than previous attempts at simulating the axisymmetric Stirling engine. A comparison of the multidimensional results, calibrated one-dimensional results, and known experimental results is shown. This preliminary comparison demonstrates that axisymmetric simulations can be very accurate, but more work remains to improve the simulations through such means as modifying the thermal equilibrium regenerator models, adding fluid-structure interactions, including radiation effects, and incorporating mechanodynamics.

  19. Analytical model for Stirling cycle machine design

    Energy Technology Data Exchange (ETDEWEB)

    Formosa, F. [Laboratoire SYMME, Universite de Savoie, BP 80439, 74944 Annecy le Vieux Cedex (France); Despesse, G. [Laboratoire Capteurs Actionneurs et Recuperation d' Energie, CEA-LETI-MINATEC, Grenoble (France)

    2010-10-15

    In order to study further the promising free piston Stirling engine architecture, there is a need of an analytical thermodynamic model which could be used in a dynamical analysis for preliminary design. To aim at more realistic values, the models have to take into account the heat losses and irreversibilities on the engine. An analytical model which encompasses the critical flaws of the regenerator and furthermore the heat exchangers effectivenesses has been developed. This model has been validated using the whole range of the experimental data available from the General Motor GPU-3 Stirling engine prototype. The effects of the technological and operating parameters on Stirling engine performance have been investigated. In addition to the regenerator influence, the effect of the cooler effectiveness is underlined. (author)

  20. Stirling engine application study

    Science.gov (United States)

    Teagan, W. P.; Cunningham, D.

    1983-01-01

    A range of potential applications for Stirling engines in the power range from 0.5 to 5000 hp is surveyed. Over one hundred such engine applications are grouped into a small number of classes (10), with the application in each class having a high degree of commonality in technical performance and cost requirements. A review of conventional engines (usually spark ignition or Diesel) was then undertaken to determine the degree to which commercial engine practice now serves the needs of the application classes and to detemine the nature of the competition faced by a new engine system. In each application class the Stirling engine was compared to the conventional engines, assuming that objectives of ongoing Stirling engine development programs are met. This ranking process indicated that Stirling engines showed potential for use in all application classes except very light duty applications (lawn mowers, etc.). However, this potential is contingent on demonstrating much greater operating life and reliability than has been demonstrated to date by developmental Stirling engine systems. This implies that future program initiatives in developing Stirling engine systems should give more emphasis to life and reliability issues than has been the case in ongoing programs.

  1. Modeling for control of a kinematic wobble-yoke Stirling engine

    NARCIS (Netherlands)

    Garcia-Canseco, Eloisa; Alvarez-Aguirre, Alejandro; Scherpen, Jacquelien M. A.

    In this paper we derive the dynamical model of a four-cylinder double-acting wobble-yoke Stirling engine. In addition to the classical thermodynamics methods that dominate the literature of Stirling mechanisms, we present a control systems viewpoint to analyze the dynamic properties of the engine.

  2. A method of computerised isotope dynamic proctography

    International Nuclear Information System (INIS)

    Papachrysostomou, M.; Ferrington, C.; Merrick, M.V.; Smith, A.N.; Western General Hospital, Edinburgh; Griffin, T.M.J.

    1992-01-01

    Patients with long-standing constipation were examined by radioisotope proctography. A radiolabelled synthetic potato mash was inserted intrarectally and the dynamic changes during simulated defaecation recorded using a gamma-camera. Computer images from the stored data illustrate changes in the anorectal angle and pelvic floor. The median (and 95% confidence intervals) of the anorectal angles were: At rest 105deg (101deg, 116deg), on voluntary contraction of the pelvic floor by 'squeezing' 91deg (81deg, 98deg), on straining 120deg (107deg, 137deg) and during evacuation 126deg (116deg, 153deg). The pelvic floor movements were: Pelvic floor ascent on voluntary contraction 28 mm (9, 34 mm), pelvic floor descent on straining -8 mm (-14, -4 mm) and descent during evacuation -27 mm (-34, -11 mm). Useful additions to previous methods are measurement of the completeness of rectal evacuation 58% (42, 77 mm), the defaecation time 64 s (50, 138 s) and the defaecation rate 0.9%/s (0.4, 1.4%/s). (orig.)

  3. Power characteristics of a Stirling radioisotope power system over the life of the mission

    International Nuclear Information System (INIS)

    Schreiber, Jeffrey G.

    2001-01-01

    Stirling radioisotope power systems are presently being considered for use on long life deep space missions. Some applications that Stirling technology has been developed for in the past could control the heat input to the engine, as was the case in the Automotive Stirling Engine (ASE) program. The combustion system could change the rate at which fuel was burned in response to the Stirling heater head temperature and the desired set point. In other cases, heat input was not controlled. An example is the solar terrestrial Advanced Stirling Conversion System (ASCS), where the heat input was a function of solar intensity and the performance of the solar concentrator and receiver. The control system for this application would measure the Stirling heater head temperature and throttle the Stirling convertor to once again, maintain the Stirling heater head temperature at the desired set point. In both of these examples, the design was driven to be cost effective. In the Stirling radioisotope power system, the heat generated by the decay in plutonium is reduced with the half-life of the isotope, and the control system must be as simple as possible and still meet the mission requirements. The most simple control system would be one that allows the Stirling power convertor to autonomously change its operating conditions in direct response to the reduced heat input, with no intervention from the control system, merely seeking a new equilibrium point as the isotope decays. This paper presents an analysis of power system performance with this simple control system, which has no feedback and does not actively alter the operating point as the isotope decays

  4. Accomplishments in free-piston stirling tests at NASA GRC

    Science.gov (United States)

    Schreiber, Jeffrey G.; Skupinski, Robert C.

    2002-01-01

    A power system based on the Stirling Radioisotope Generator (SRG) has been identified for potential use on deep space missions, as well as for Mars rovers that may benefit from extended operation. The Department of Energy (DOE) has responsibility for developing the generator and the NASA Glenn Research Center (GRC) is supporting DOE in this effort. The generator is based on a free-piston Stirling power convertor that has been developed by the Stirling Technology Company (STC) under contract to DOE. The generator would be used as a high-efficiency alternative to the Radioisotope Thermoelectric Generators (RTGs) that have been used on many previous missions. The increased efficiency leads to a factor of 3 to 4 reduction in the inventory of plutonium required to heat the generator. GRC has been involved in the development of Stirling power conversion technology for over 25 years. The support provided to this project by GRC has many facets and draws upon the lab's scientists and engineers that have gained experience in applying their skills to the previous Stirling projects. This has created a staff with an understanding of the subtleties involved in applying their expertise to Stirling systems. Areas include materials, structures, tribology, controls, electromagnetic interference, permanent magnets, alternator analysis, structural dynamics, and cycle performance. One of the key areas of support to the project is in the performance testing of the free-piston Stirling convertors. Since these power convertors are the smallest, lowest power Stirling machines that have been tested at GRC, a new laboratory was equipped for this project. Procedures and test plans have been created, instrumentation and data systems developed, and Stirling convertors have been tested. This paper will describe the GRC test facility, the test procedures that are used, present some of the test results and outline plans for the future. .

  5. Stirling to Flight Initiative

    Science.gov (United States)

    Hibbard, Kenneth E.; Mason, Lee S.; Ndu, Obi; Smith, Clayton; Withrow, James P.

    2016-01-01

    NASA has a consistent need for radioisotope power systems (RPS) to enable robotic scientific missions for planetary exploration that has been present for over four decades and will continue into the foreseeable future, as documented in the most recent Planetary Science Decadal Study Report. As RPS have evolved throughout the years, there has also grown a desire for more efficient power systems, allowing NASA to serve as good stewards of the limited plutonium-238 (238Pu), while also supporting the ever-present need to minimize mass and potential impacts to the desired science measurements. In fact, the recent Nuclear Power Assessment Study (NPAS) released in April 2015 resulted in several key conclusion regarding RPS, including affirmation that RPS will be necessary well into the 2030s (at least) and that 238Pu is indeed a precious resource requiring efficient utilization and preservation. Stirling Radioisotope Generators (SRGs) combine a Stirling cycle engine powered by a radioisotope heater unit into a single generator system. Stirling engine technology has been under development at NASA Glenn Research Center (GRC) in partnership with the Department of Energy (DOE) since the 1970's. The most recent design, the 238Pu-fueled Advanced Stirling Radioisotope Generator (ASRG), was offered as part of the NASA Discovery 2010 Announcement of Opportunity (AO). The Step-2 selections for this AO included two ASRG-enabled concepts, the Titan Mare Explorer (TiME) and the Comet Hopper (CHopper), although the only non-nuclear concept, InSight, was ultimately chosen. The DOE's ASRG contract was terminated in 2013. Given that SRGs utilize significantly less 238Pu than traditional Radioisotope Thermoelectric Generators (RTGs) - approximately one quarter of the nuclear fuel, to produce similar electrical power output - they provide a technology worthy of consideration for meeting the aforementioned NASA objectives. NASA's RPS Program Office has recently investigated a new Stirling to

  6. Stirling engine piston ring

    Science.gov (United States)

    Howarth, Roy B.

    1983-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  7. A Stirling Idea

    Science.gov (United States)

    1998-01-01

    Stirling Technology Company developed the components for its BeCOOL line of Cryocoolers with the help of a series of NASA SBIRs (Small Business Innovative Research), through Goddard Space Flight Center and Marshall Space Flight Center. Features include a hermetically sealed design, compact size, and silent operation. The company has already placed several units with commercial customers for computer applications and laboratory use.

  8. Stirling in Another Context.

    Science.gov (United States)

    Papademetriou, Peter

    1981-01-01

    An analysis and a critique of how remodeling and extension of the Rice University School of Architecture, by James Stirling, Michael Wilford, and Associates, fits into the campus plan and its eclectic style established early in this century. (Author/MLF)

  9. Dynamics of mobile form of plutonium isotopes in soils within 10-km zone of Chernobyl NPP

    International Nuclear Information System (INIS)

    Shuktomova, I.I.

    1996-01-01

    The dynamics of the mobile forms of plutonium isotopes depending on the time of there presence in environment were studied on samples of five soil varieties within the limits of the 10-km zone of Chernobyl NPP. Seasonal dynamic study of the extracted plutonium isotopes showed the increase (5-10 fold) in the amount of mobile forms of radionuclides in all soil samples. Studying the dynamics of total sum of mobile forms of isotopes in soils showed their decrease in general

  10. The Stirling engine accelerates.; Der Stirling-Motor gibt Gas.

    Energy Technology Data Exchange (ETDEWEB)

    Pfannstiel, Dieter [DiWiTech - Ingenieurpraxis fuer technische und wissenschaftliche Dienstleistungen, Breitenbach a.H. (Germany)

    2010-01-15

    At this moment, Stirling engines are the most outstanding micro technology of combined heat and power generation. The free piston machine combines the principle of the conventional Stirling engine with a modern linear generator for power generation utilizing waste heat for the heating of houses or hot water tanks. All large manufacturers concern themselves with this technology and develop devices based on the Stirling engine. The overview contribution under consideration describes the current level of development of the Stirling devices of different manufacturers. In nearly two years, these devices will serially be produced in the market.

  11. Isotopic differentiation and sublattice melting in dense dynamic ice

    Science.gov (United States)

    Hermann, Andreas; Ashcroft, N. W.; Hoffmann, Roald

    2013-12-01

    The isotopes of hydrogen provide a unique exploratory laboratory for examining the role of zero point energy (ZPE) in determining the structural and dynamic features of the crystalline ices of water. There are two critical regions of high pressure: (i) near 1 TPa and (ii) near the predicted onset of metallization at around 5 TPa. At the lower pressure of the two, we see the expected small isotopic effects on phase transitions. Near metallization, however, the effects are much greater, leading to a situation where tritiated ice could skip almost entirely a phase available to the other isotopomers. For the higher pressure ices, we investigate in some detail the enthalpics of a dynamic proton sublattice, with the corresponding structures being quite ionic. The resistance toward diffusion of single protons in the ground state structures of high-pressure H2O is found to be large, in fact to the point that the ZPE reservoir cannot overcome these. However, the barriers toward a three-dimensional coherent or concerted motion of protons can be much lower, and the ensuing consequences are explored.

  12. Integrated Stirling Convertor and Hall Thruster Test Conducted

    Science.gov (United States)

    Mason, Lee S.

    2002-01-01

    An important aspect of implementing Stirling Radioisotope Generators on future NASA missions is the integration of the generator and controller with potential spacecraft loads. Some recent studies have indicated that the combination of Stirling Radioisotope Generators and electric propulsion devices offer significant trip time and payload fraction benefits for deep space missions. A test was devised to begin to understand the interactions between Stirling generators and electric thrusters. An electrically heated RG- 350 (350-W output) Stirling convertor, designed and built by Stirling Technology Company of Kennewick, Washington, under a NASA Small Business Innovation Research agreement, was coupled to a 300-W SPT-50 Hall-effect thruster built for NASA by the Moscow Aviation Institute (RIAME). The RG-350 and the SPT-50 shown, were installed in adjacent vacuum chamber ports at NASA Glenn Research Center's Electric Propulsion Laboratory, Vacuum Facility 8. The Stirling electrical controller interfaced directly with the Hall thruster power-processing unit, both of which were located outside of the vacuum chamber. The power-processing unit accepted the 48 Vdc output from the Stirling controller and distributed the power to all the loads of the SPT-50, including the magnets, keeper, heater, and discharge. On February 28, 2001, the Glenn test team successfully operated the Hall-effect thruster with the Stirling convertor. This is the world's first known test of a dynamic power source with electric propulsion. The RG-350 successfully managed the transition from the purely resistive load bank within the Stirling controller to the highly capacitive power-processing unit load. At the time of the demonstration, the Stirling convertor was operating at a hot temperature of 530 C and a cold temperature of -6 C. The linear alternator was producing approximately 250 W at 109 Vac, while the power-processing unit was drawing 175 W at 48 Vdc. The majority of power was delivered to the

  13. Stirling cycle engine

    Science.gov (United States)

    Lundholm, Gunnar

    1983-01-01

    In a Stirling cycle engine having a plurality of working gas charges separated by pistons reciprocating in cylinders, the total gas content is minimized and the mean pressure equalization among the serial cylinders is improved by using two piston rings axially spaced at least as much as the piston stroke and by providing a duct in the cylinder wall opening in the space between the two piston rings and leading to a source of minimum or maximum working gas pressure.

  14. Stirling engine power control

    Science.gov (United States)

    Fraser, James P.

    1983-01-01

    A power control method and apparatus for a Stirling engine including a valved duct connected to the junction of the regenerator and the cooler and running to a bypass chamber connected between the heater and the cylinder. An oscillating zone of demarcation between the hot and cold portions of the working gas is established in the bypass chamber, and the engine pistons and cylinders can run cold.

  15. Stirling engine design manual

    Science.gov (United States)

    Martini, W. R.

    1978-01-01

    This manual is intended to serve both as an introduction to Stirling engine analysis methods and as a key to the open literature on Stirling engines. Over 800 references are listed and these are cross referenced by date of publication, author and subject. Engine analysis is treated starting from elementary principles and working through cycles analysis. Analysis methodologies are classified as first, second or third order depending upon degree of complexity and probable application; first order for preliminary engine studies, second order for performance prediction and engine optimization, and third order for detailed hardware evaluation and engine research. A few comparisons between theory and experiment are made. A second order design procedure is documented step by step with calculation sheets and a worked out example to follow. Current high power engines are briefly described and a directory of companies and individuals who are active in Stirling engine development is included. Much remains to be done. Some of the more complicated and potentially very useful design procedures are now only referred to. Future support will enable a more thorough job of comparing all available design procedures against experimental data which should soon be available.

  16. Stirling Engine with Unidirectional Gas Flow

    OpenAIRE

    Blumbergs, Ilmars

    2014-01-01

    In this study, a Stirling engine with unidirectional gas flow configuration of beta type Stirling engine is described and studied from kinematic and thermodynamics points of view. Some aspects of the Stirling engine with unidirectional gas flow engine are compared to classic beta type Stirling engines. The aim of research has been to develop a new type of Stirling engine, using SolidWorks 3D design software and Flow Simulation software. In the development process, special attention has been d...

  17. Flow dynamics in distillation columns packed with Dixon rings as used in isotope separation

    International Nuclear Information System (INIS)

    Gilath, C.; Cohen, H.; Wolf, D.

    1977-01-01

    Packed distillation columns are common in isotope separation. The pressure drop serves as an indication for the hydrodynamic state of the column. Models were formulated for flow and pressure drop dynamics in packed distillation columns. These models were confirmed on columns packed with Dixon rings and operated with water for separation of oxygen isotopes. Liquid holdup displacement is very important in isotope separation practice. Experiments proved that distillation columns packed with Dixon rings exhibit a behaviour close to plug flow. (author)

  18. Stirling Engine Configuration Selection

    Directory of Open Access Journals (Sweden)

    Jose Egas

    2018-03-01

    Full Text Available Unlike internal combustion engines, Stirling engines can be designed to work with many drive mechanisms based on the three primary configurations, alpha, beta and gamma. Hundreds of different combinations of configuration and mechanical drives have been proposed. Few succeed beyond prototypes. A reason for poor success is the use of inappropriate configuration and drive mechanisms, which leads to low power to weight ratio and reduced economic viability. The large number of options, the lack of an objective comparison method, and the absence of a selection criteria force designers to make random choices. In this article, the pressure—volume diagrams and compression ratios of machines of equal dimensions, using the main (alpha, beta and gamma crank based configurations as well as rhombic drive and Ross yoke mechanisms, are obtained. The existence of a direct relation between the optimum compression ratio and the temperature ratio is derived from the ideal Stirling cycle, and the usability of an empirical low temperature difference compression ratio equation for high temperature difference applications is tested using experimental data. It is shown that each machine has a different compression ratio, making it more or less suitable for a specific application, depending on the temperature difference reachable.

  19. The Stirling engine

    International Nuclear Information System (INIS)

    Dunn, P.D.

    1989-01-01

    The Stirling engine can be used with any heat source including direct flame, heating from oil, gas, wood or coal combustors, by solar and by nuclear energy. As an alternative to conventional combustors fuels such as coal, oil, gas, vegetable waste can be combusted in a fluidized bed. The engine can be heated by coupling it directly to one of these sources of heat or it can be separated from the heat source and the heat transported by a heat pipe. There is clearly considerable flexibility in the choice of heat source. A major economic penalty is the need for a high temperature heat exchanger to transfer the heat to the engine working fluid from the heat source. Since in order to achieve good heat transfer a large surface area is needed and hence a complicated arrangement of small bore piping. Since the working fluid is not consumed an expensive substance such as helium can be used; however, if the power is to be extracted by a mechanical shaft it is necessary to design a seal between the engine body and the output shaft which will not allow any significant loss of helium. The seal problem is still one of the major technical difficulties in the development of Stirling engines using Helium or Hydrogen as the working fluid. For this reason interest in using air as the working fluid in lower speed engines has revived. 14 refs, 19 figs

  20. Advanced Stirling Convertor Update

    Science.gov (United States)

    Wood, J. Gary; Carroll, Cliff; Matejczyk, Dan; Penswick, L. B.; Soendker, E.

    2006-01-01

    This paper reports on the 88 We Advanced Stirling Convertor (ASC) currently being developed under Phase II of a NASA NRA program for possible use in advanced high specific power radioisotope space power systems. An early developmental unit, the Frequency Test Bed (FTB) which was built and tested in Phase I demonstrated 36% efficiency. The ASC-1 currently being developed under Phase II, uses a high temperature heater head to allow for operation at 850 °C and is expected to have an efficiency approaching 40% (based on AC electrical out) at a temperature ratio of 3.1. The final lightweight ASC-2 convertor to be developed in Phase III is expected to have a mass of approximately 1 kg. The implementation of the ASC would allow for much higher specific power radioisotope power systems, requiring significantly less radioisotope fuel than current systems. The first run of the ASC-1 occurred in September 2005, and full temperature operation was achieved in early October 2005. Presented is an update on progress on the ASC program as well as the plans for future development. Also presented are efforts being performed to ensure the ASC has the required long life already demonstrated in free-piston Stirling cryocoolers.

  1. Structure of Li, Be And B isotopes studied with quantum molecular dynamic model

    International Nuclear Information System (INIS)

    Abdel-Hafiez, A.; Saleh, Z.A.

    2000-01-01

    Quantum molecular dynamics (QMD) is applied to study the ground state properties of Li, Be and B isotopes. The model Hamiltonian includes both two-and three-body density dependent interactions, a Coulomb term, and a momentum dependent Pauli potential. With parameters which guarantee the infinite nuclear matter properties, the QMD model can only reproduce the binding energies for Be and B isotopes. The experimental root mean square radii of the Li, Be and B isotopes are not sufficiently reproduced by these parameters. It is shown, however, that the binding energies and root mean square radii of these isotopes can simultaneously be reproduced in the lower density limit of the potential parameters

  2. MEMS Stirling Cooler Development Update

    Science.gov (United States)

    Moran, Matthew E.; Wesolek, Danielle

    2003-01-01

    This presentation provides an update on the effort to build and test a prototype unit of the patented MEMS Stirling cooler concept. A micro-scale regenerator has been fabricated by Polar Thermal Technologies and is currently being integrated into a Stirling cycle simulator at Johns Hopkins University Applied Physics Laboratory. A discussion of the analysis, design, assembly, and test plans for the prototype will be presented.

  3. Active Vibration Reduction of the Advanced Stirling Convertor

    Science.gov (United States)

    Wilson, Scott D.; Metscher, Jonathan F.; Schifer, Nicholas A.

    2016-01-01

    Stirling Radioisotope Power Systems (RPS) are being developed as an option to provide power on future space science missions where robotic spacecraft will orbit, flyby, land or rove. A Stirling Radioisotope Generator (SRG) could offer space missions a more efficient power system that uses one fourth of the nuclear fuel and decreases the thermal footprint compared to the current state of the art. The Stirling Cycle Technology Development (SCTD) Project is funded by the RPS Program to developing Stirling-based subsystems, including convertors and controller maturation efforts that have resulted in high fidelity hardware like the Advanced Stirling Radioisotope Generator (ASRG), Advanced Stirling Convertor (ASC), and ASC Controller Unit (ACU). The SCTD Project also performs research to develop less mature technologies with a wide variety of objectives, including increasing temperature capability to enable new environments, improving system reliability or fault tolerance, reducing mass or size, and developing advanced concepts that are mission enabling. Active vibration reduction systems (AVRS), or "balancers", have historically been developed and characterized to provide fault tolerance for generator designs that incorporate dual-opposed Stirling convertors or enable single convertor, or small RPS, missions. Balancers reduce the dynamic disturbance forces created by the power piston and displacer internal moving components of a single operating convertor to meet spacecraft requirements for induced disturbance force. To improve fault tolerance for dual-opposed configurations and enable single convertor configurations, a breadboard AVRS was implemented on the Advanced Stirling Convertor (ASC). The AVRS included a linear motor, a motor mount, and a closed-loop controller able to balance out the transmitted peak dynamic disturbance using acceleration feedback. Test objectives included quantifying power and mass penalty and reduction in transmitted force over a range of ASC

  4. Isotope yield ratios as a probe of the reaction dynamics

    International Nuclear Information System (INIS)

    Trautmann, W.; Hildenbrand, K.D.; Lynen, U.; Mueller, W.F.J.; Rabe, H.J.; Sann, H.; Stelzer, H.; Trockel, R.; Wada, R.; Brummund, N.; Glasow, R.; Kampert, K.H.; Santo, R.; Eckert, E.M.; Pochodzalla, J.; Bock, I.; Pelte, D.

    1987-04-01

    Isotopically resolved yields of particles and complex fragments from 12 C and 18 O induced reactions on 53 Ni, 54 Ni, Ag, and 197 Au in the intermediate range of bombarding energies 30 MeV ≤ E/A ≤ 84 MeV were measured. The systematic variation of the deduced isotope yield ratios with projectile and target is used to determine the degree of N/Z equilibration achieved and to establish time scales for the reaction process. A quantum statistical model is employed in order to derive entropies of the emitting systems from the measured isotope yield ratios. (orig.)

  5. Free-piston Stirling technology for space power

    International Nuclear Information System (INIS)

    Slaby, J.G.

    1994-01-01

    An overview is presented of the NASA Lewis Research Center free-piston Stirling engine activities directed toward space power. This work is being carried out under NASA's new Civil Space Technology Initiative (CSTI). The overall goal of CSTI's High Capacity Power element is to develop the technology base needed to meet the long duration, high capacity power requirements for future NASA space missions. The Stirling cycle offers an attractive power conversion concept for space power needs. Discussed in this paper is the completion of the Space Power Demonstrator Engine (SPDE) testing - culminating in the generation of 25 kW of engine power from a dynamically-balanced opposed-piston Stirling engine at a temperature ratio of 2.0. Engine efficiency was approximately 22 percent. The SPDE recently has been divided into two separate single-cylinder engines, called Space Power Research Engines (SPRE), that now serve as test beds for the evaluation of key technology disciplines. These disciplines include hydrodynamic gas bearings, high-efficiency linear alternators, space qualified heat pipe heat exchangers, oscillating flow code validation, and engine loss understanding. The success of the SPDE at 650 K has resulted in a more ambitious Stirling endeavor - the design, fabrication, test and evaluation of a designed-for-space 25 kW per cylinder Stirling Space Engine (SSE). The SSE will operate at a hot metal temperature of 1050 K using superalloy materials. This design is a low temperature confirmation of the 1300 K design. It is the 1300 K free-piston Stirling power conversion system that is the ultimate goal; to be used in conjunction with the SP-100 reactor. The approach to this goal is in three temperature steps. However, this paper concentrates on the first two phases of this program - the 650 K SPDE and the 1050 K SSE

  6. Simulation program for multiple expansion Stirling machines

    International Nuclear Information System (INIS)

    Walker, G.; Weiss, M.; Fauvel, R.; Reader, G.; Bingham, E.R.

    1992-01-01

    Multiple expansion Stirling machines have been a topic of interest at the University of Calgary for some years. Recently a second-order computer simulation program with integral graphics package for Stirling cryocoolers with up to four stages of expansion were developed and made available to the Stirling community. Adaptation of the program to multiple expansion Stirling power systems is anticipated. This paper briefly introduces the program and presents a specimen result

  7. Dynamics of radioactive lead isotopes in the global environmental atmosphere

    International Nuclear Information System (INIS)

    Koike, Yuya; Kosako, Toshiso

    2006-01-01

    Fundamental information of radioactive lead isotopes, which used as the atmospheric tracer in the global environmental atmosphere, is reviewed. Emanation and exhalation of Rn and Tn, parent nuclide, is stated. Some reports on measurement and application of short-lived lead isotopes are reported. Transfer of radioactive lead isotopes in the atmosphere, vertical profiles of radon, thoron, and short-lived lead isotopes for different turbulent mixing conditions, deposition to aerosol, basic processes of Rn decay product behavior in air defining 'unattached' and 'aerosol-attached' activities, seasonal variation of atmospheric 210 Pb concentration at Beijing and Chengdu, seasonal variation of atmospheric 212 Pb concentration at several observation sites in Japan Islands, and variation in the atmospheric concentration of 212 Pb along with SO 2 are shown. (S.Y.)

  8. Isotope effects in lithium hydride and lithium deuteride crystals by molecular dynamics simulations.

    Science.gov (United States)

    Dammak, Hichem; Antoshchenkova, Ekaterina; Hayoun, Marc; Finocchi, Fabio

    2012-10-31

    Molecular dynamics (MD) simulations have been carried out to study isotope effects in lithium hydride and lithium deuteride crystals. Quantum effects on nuclear motion have been included through a quantum thermal bath (QTB). The interatomic forces were described either within the density functional theory (DFT) in the generalized gradient approximation (GGA) or by the phenomenological approach using the shell model. For both models, the isotopic shift in the lattice parameter can be successfully predicted by QTB-MD simulations. The slope of the experimental isotopic shift in pressure is satisfactorily reproduced by QTB-MD within DFT-GGA, in contrast to both density functional perturbation theory and QTB-MD with the shell model. We have analyzed the reasons for these discrepancies through the vibrational densities of states and the isotopic shifts in bulk modulus. The results illustrate the importance of anharmonic contributions to vibrations and to the isotopic pressure shift between LiH and LiD.

  9. Soil organic matter (SOM) dynamics determined by stable isotope techniques

    International Nuclear Information System (INIS)

    Gerzabek, M. H.

    1998-09-01

    Being aware of limitations and possible bias the 13 C natural abundance technique using the different 13 C enrichments in plants with differing photosynthetic pathways in a powerful tool to quantify turnover processes, both in long-term field studies and short-term laboratory experiments. Special care is needed in choosing reference plots and the proper number of replicate samples. The combination of 13 C and 14 C measurements has a high potential for a further improvement of isotope techniques in SOM studies. Natural abundance of 15 N is less powerful with respect to quantification of SOM processes than the isotope dilution technique. However its usefulness could be distinctly improved by introducing other stable isotopes into the studies.(author)

  10. Overall performance of the duplex Stirling refrigerator

    International Nuclear Information System (INIS)

    Erbay, L. Berrin; Ozturk, M. Mete; Doğan, Bahadır

    2017-01-01

    Highlights: • Overall performance coefficient of duplex Stirling refrigerator was investigated. • A definite region for the coefficient of performance of the refrigerator in duplex Stirling is identified. • A definite region for the thermal efficiency of the heat engine in duplex Stirling is identified. • Benchmark values and design bounds of the duplex Stirling refrigerator were obtained. - Abstract: The duplex Stirling refrigerator is an integrated refrigerator consists of Stirling cycle engine and Stirling cycle refrigerator used for cooling. The equality of the work generation of the heat engine to the work consumption of the refrigerator is the primary constraint of the duplex Stirling. The duplex Stirling refrigerator is investigated thermodynamically by considering the effects of constructional and operational parameters which are namely the temperature ratios for heat engine and refrigerator, and the compression ratios for both sides. The primary concern is given to the parametric effects on the overall coefficient of performance of the duplex Stirling refrigerator. The given diagrams provide a design bounds and benchmark results that allows seeing the big picture about the cooling load and heat input relation. Moreover they ease to determine the corresponding work rate to the target cooling load. As regard to the obtained results, a definite region for coefficient of performance of the refrigerator and a definite region for the thermal efficiency of the heat engine of the duplex Stirling are identified.

  11. Derivation of basic equations for rigorous dynamic simulation of cryogenic distillation column for hydrogen isotope separation

    International Nuclear Information System (INIS)

    Kinoshita, Masahiro; Naruse, Yuji

    1981-08-01

    The basic equations are derived for rigorous dynamic simulation of cryogenic distillation columns for hydrogen isotope separation. The model accounts for such factors as differences in latent heat of vaporization among the six isotopic species of molecular hydrogen, decay heat of tritium, heat transfer through the column wall and nonideality of the solutions. Provision is also made for simulation of columns with multiple feeds and multiple sidestreams. (author)

  12. Stirling Microregenerators Fabricated and Tested

    Science.gov (United States)

    Moran, Matthew E.

    2004-01-01

    A mesoscale Stirling refrigerator patented by the NASA Glenn Research Center is currently under development. This refrigerator has a predicted efficiency of 30 percent of Carnot and potential uses in electronics, sensors, optical and radiofrequency systems, microarrays, and microsystems. The mesoscale Stirling refrigerator is most suited to volume-limited applications that require cooling below the ambient or sink temperature. Primary components of the planar device include two diaphragm actuators that replace the pistons found in traditional-scale Stirling machines and a microregenerator that stores and releases thermal energy to the working gas during the Stirling cycle. Diaphragms are used to eliminate frictional losses and bypass leakage concerns associated with pistons, while permitting reversal of the hot and cold sides of the device during operation to allow precise temperature control. Three candidate microregenerators were fabricated under NASA grants for initial evaluation: two constructed of porous ceramic, which were fabricated by Johns Hopkins Applied Physics Laboratory, and one made of multiple layers of nickel and photoresist, which was fabricated by Polar Thermal Technologies. The candidate regenerators are being tested by Johns Hopkins Applied Physics in a custom piezoelectric-actuated test apparatus designed to produce the Stirling refrigeration cycle. In parallel with the regenerator testing, Johns Hopkins is using deep reactive ion etching to fabricate electrostatically driven, comb-drive diaphragm actuators. These actuators will drive the Stirling cycle in the prototype device. The top photograph shows the porous ceramic microregenerators. Two microregenerators were fabricated with coarse pores and two with fine pores. The bottom photograph shows the test apparatus parts for evaluating the microregenerators, including the layered nickel-and-photoresist regenerator fabricated using LIGA techniques.

  13. Chemical Ligation and Isotope Labeling to Locate Dynamic Effects during Catalysis by Dihydrofolate Reductase.

    Science.gov (United States)

    Luk, Louis Y P; Ruiz-Pernía, J Javier; Adesina, Aduragbemi S; Loveridge, E Joel; Tuñón, Iñaki; Moliner, Vincent; Allemann, Rudolf K

    2015-07-27

    Chemical ligation has been used to alter motions in specific regions of dihydrofolate reductase from E. coli and to investigate the effects of localized motional changes on enzyme catalysis. Two isotopic hybrids were prepared; one with the mobile N-terminal segment containing heavy isotopes ((2) H, (13) C, (15) N) and the remainder of the protein with natural isotopic abundance, and the other one with only the C-terminal segment isotopically labeled. Kinetic investigations indicated that isotopic substitution of the N-terminal segment affected only a physical step of catalysis, whereas the enzyme chemistry was affected by protein motions from the C-terminal segment. QM/MM studies support the idea that dynamic effects on catalysis mostly originate from the C-terminal segment. The use of isotope hybrids provides insights into the microscopic mechanism of dynamic coupling, which is difficult to obtain with other studies, and helps define the dynamic networks of intramolecular interactions central to enzyme catalysis. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

  14. New 5 Kilowatt Free-Piston Stirling Space Converter Developments

    Science.gov (United States)

    Brandhorst, Henry W.

    2007-01-01

    NASA has recently funded development of a 5 kW (or greater) free-piston Stirling conversion system for reactor power systems. A nominal 5 kW converter allows two of these units to be dynamically balanced. A group of three dual-convertor combinations would yield the desired 30 kW. The status of this program will be presented. Goals include a specific power in excess of 140 W/kg at the converter level, lifetime in excess of five years and AC output. The initial step is the design and development of a nominal 5 kW per cylinder Stirling converter assembly (SCA) which will serve as a prototype of one or more SCAs that will make up the final 30 kW Stirling Converter Power System. Assumed requirements for this new converter for lunar fission power systems will be presented. The primary objective of this development effort will be to demonstrate a 5 kW SCA that can be tested to validate the viability of Stirling technology for space fission surface power systems.

  15. Multi-d CFD Modeling of a Free-piston Stirling Convertor at NASA Glenn

    Science.gov (United States)

    Wilson, Scott D.; Dyson, Rodger W.; Tew, Roy C.; Ibrahim, Mounir B.

    2004-01-01

    A high efficiency Stirling Radioisotope Generator (SRG) is being developed for possible use in long duration space science missions. NASA s advanced technology goals for next generation Stirling convertors include increasing the Carnot efficiency and percent of Carnot efficiency. To help achieve these goals, a multidimensional Computational Fluid Dynamics (CFD) code is being developed to numerically model unsteady fluid flow and heat transfer phenomena of the oscillating working gas inside Stirling convertors. Simulations of the Stirling convertors for the SRG will help characterize the thermodynamic losses resulting from fluid flow and heat transfer between the working gas and solid walls. The current CFD simulation represents approximated 2-dimensional convertor geometry. The simulation solves the Navier Stokes equations for an ideal helium gas oscillating at low speeds. The current simulation results are discussed.

  16. Overview of the 1985 NASA Lewis Research Center SP-100 free-piston stirling engine activities

    International Nuclear Information System (INIS)

    Slaby, J.G.

    1985-01-01

    An overview of the 1985 (NASA) Lewis Research Center free-piston Stirling engine activities in support of the SP-100 Program is presented. The SP-100 program is being conducted in support of the Department of Advanced Research Projects Agency (DARPA) and the Department of Energy (DOE), and NASA. This effort is keyed on the design, fabrication, assembly, and testing of a 25 kW /SUB e/ Stirling space-power technology-feasibility demonstrator engine. Another facet of the SP-100 project covers the status of a 9000-hr goal endurance test conducted on a 2 kW /SUB e/ free-piston Stirling/ linear alternator system employing hydrostatic gas bearings. Dynamic balancing of the RE-1000 engine (a 1 kW /SUB e/ free-piston Stirling engine) using a passive dynamic absorber will be discussed along with the results of a parametric study showing the relationships of Stirling power converter specific weight and efficiency as functions of Stirling engine heater to cooler temperature ratio. Planned tests will be described covering a hydrodynamic gas bearing concept for potential SP-100 application

  17. Quantifying mercury isotope dynamics in captive Pacific bluefin tuna (Thunnus orientalis

    Directory of Open Access Journals (Sweden)

    Sae Yun Kwon

    2016-02-01

    Full Text Available Abstract Analyses of mercury (Hg isotope ratios in fish tissues are used increasingly to infer sources and biogeochemical processes of Hg in natural aquatic ecosystems. Controlled experiments that can couple internal Hg isotope behavior with traditional isotope tracers (δ13C, δ15N can improve the applicability of Hg isotopes as natural ecological tracers. In this study, we investigated changes in Hg isotope ratios (δ202Hg, Δ199Hg during bioaccumulation of natural diets in the pelagic Pacific bluefin tuna (Thunnus orientalis; PBFT. Juvenile PBFT were fed a mixture of natural prey and a dietary supplement (60% Loligo opalescens, 31% Sardinops sagax, 9% gel supplement in captivity for 2914 days, and white muscle tissues were analyzed for Hg isotope ratios and compared to time in captivity and internal turnover of δ13C and δ15N. PBFT muscle tissues equilibrated to Hg isotope ratios of the dietary mixture within ∼700 days, after which we observed a cessation in further shifts in Δ199Hg, and small but significant negative δ202Hg shifts from the dietary mixture. The internal behavior of Δ199Hg is consistent with previous fish studies, which showed an absence of Δ199Hg fractionation during Hg bioaccumulation. The negative δ202Hg shifts can be attributed to either preferential excretion of Hg with higher δ202Hg values or individual variability in captive PBFT feeding preferences and/or consumption rates. The overall internal behavior of Hg isotopes is similar to that described for δ13C and δ15N, though observed Hg turnover was slower compared to carbon and nitrogen. This improved understanding of internal dynamics of Hg isotopes in relation to δ13C and δ15N enhances the applicability of Hg isotope ratios in fish tissues for tracing Hg sources in natural ecosystems.

  18. Innovation at Stirling

    Science.gov (United States)

    1998-11-01

    The 24th Stirling Meeting of the Scottish Branch of the Institute of Physics was held on 21 May 1998. It was, for the first time, coupled to a Physics Update Course, which then continued in the Heriot-Watt University over the following two days. This encouraged many more exhibitors to come to Stirling where some 220 physics teachers were present. Ten manufacturers, five publishers and, of course, the ASE and the Institute of Physics exhibited materials during the conference. Morning In his introductory remarks Jack Woolsey reminded teachers that a great deal of information about the Scottish Qualifications Authority was available on the web (http://www.sqa.org.uk). Lorna Neill chaired the morning session, which was devoted to teaching chips and assessing pupils! Tony Joyce (Motorola) emphasized the need to invest in the skills required by the electronics industry. There has been an explosion in the demand for microchips and Motorola, together with Edinburgh University, Compugraphics and Scottish Enterprise, have produced a number of `teaching chips' which are being used throughout Britain and abroad. Les Haworth (Edinburgh University) discussed the construction, operating principles and educational relevance of MOS devices. MOSFETs, he claimed, are the best vehicle for early teaching of device physics. Andrew Moore (Balerno High School) gave an entertaining presentation in which he suggested ways of using the `teaching chips' in practice. Although there were many good information sheets with suggested experiments and investigations, teachers often found it difficult to tailor them to specific courses. To reduce hassle Andrew recommended using the Teaching Chip Project Board which was now available. It was particularly useful for practical investigations at Standard Grade. For the question session Jim Jamieson (SSERC) and Walter Whitelaw (Edinburgh Council) joined the three speakers. Ian Kennedy (Kilwinning Academy) described a fascinating system, developed in his

  19. Stirling engine with pressurized crankcase

    Science.gov (United States)

    Corey, John A.

    1988-01-01

    A two piston Stirling engine wherein the pistons are coupled to a common crankshaft via bearing means, the pistons include pad means to minimize friction between the pistons and the cylinders during reciprocation of the pistons, means for pressurizing the engine crankcase, and means for cooling the crankshaft and the bearing means eliminating the need for oil in the crankcase.

  20. Free-Piston Stirling Engines

    Science.gov (United States)

    Shaltens, Richard K.

    1989-01-01

    Engines promise cost-effective solar-power generation. Report describes two concepts for Stirling-engine systems for conversion of solar heat to electrical energy. Recognized most promising technologies for meeting U.S. Department of Energy goals for performance and cost for terrestrial electrical-energy sources.

  1. Stability of split Stirling refrigerators

    NARCIS (Netherlands)

    Waele, de A.T.A.M.; Liang, W.

    2009-01-01

    In many thermal systems spontaneous mechanical oscillations are generated under the influence of large temperature gradients. Well-known examples are Taconis oscillations in liquid-helium cryostats and oscillations in thermoacoustic systems. In split Stirling refrigerators the compressor and the

  2. RE-1000 free-piston Stirling engine update

    Science.gov (United States)

    Schreiber, J. G.

    1985-01-01

    A free piston Stirling engine was tested. The tests performed over the past several years on the single cylinder engine were designed to investigate the dynamics of a free piston Stirling engine. The data are intended to be used primarily for computer code validation. The tests designed to investigate the sensitivity of the engine performance to variations in working space pressure, heater and cooler temperatures, regenerator porosity, power piston mass and displacer dynamics were completed. In addition, some data were recorded with alternate working fluids. A novel resonant balance system for the engine was also tested. Some preliminary test results of the tests performed are presented along with an outline of future tests to be run with the engine coupled to a hydraulic output unit. A description of the hydraulic output unit is given.

  3. Parametric System Model for a Stirling Radioisotope Generator

    Science.gov (United States)

    Schmitz, Paul C.

    2015-01-01

    A Parametric System Model (PSM) was created in order to explore conceptual designs, the impact of component changes and power level on the performance of the Stirling Radioisotope Generator (SRG). Using the General Purpose Heat Source (GPHS approximately 250 Wth) modules as the thermal building block from which a SRG is conceptualized, trade studies are performed to understand the importance of individual component scaling on isotope usage. Mathematical relationships based on heat and power throughput, temperature, mass, and volume were developed for each of the required subsystems. The PSM uses these relationships to perform component- and system-level trades.

  4. Interference of scalp and skull with dynamic isotope studies of brain

    International Nuclear Information System (INIS)

    Oldendorf, W.H.

    1972-01-01

    The overlying scalp and skull create artifacts in external brain counting measurements in which isotope appears in these tissues. It is much less of a problem in dynamic studies since high levels of superficial isotope are not found in the first few seconds after introduction into the blood by any anatomic route. Diffusible tracers concentrate somewhat less in the scalp and skull than in the brain immediately after injection by any route. Nondiffusible tracers of low molecular weight attain a much higher concentration in the scalp than the brain only after about the first minute because of passage from plasma to scalp extracellular fluid. This equilibration does not occur in brain because of the blood-brain barrier. Scalp and skull thus create much less of a problem with brief dynamic studies than with chronic long-term studies. Some physical considerations of external collimation are discussed, and means are suggested to minimize superficial isotope contributions to brain counts. (U.S.)

  5. Technology verification phase. Dynamic isotope power system. Final report

    International Nuclear Information System (INIS)

    Halsey, D.G.

    1982-01-01

    The Phase I requirements of the Kilowatt Isotope Power System (KIPS) program were to make a detailed Flight System Conceptual Design (FSCD) for an isotope fueled organic Rankine cycle power system and to build and test a Ground Demonstration System (GDS) which simulated as closely as possible the operational characteristics of the FSCD. The activities and results of Phase II, the Technology Verification Phase, of the program are reported. The objectives of this phase were to increase system efficiency to 18.1% by component development, to demonstrate system reliability by a 5000 h endurance test and to update the flight system design. During Phase II, system performance was improved from 15.1% to 16.6%, an endurance test of 2000 h was performed while the flight design analysis was limited to a study of the General Purpose Heat Source, a study of the regenerator manufacturing technique and analysis of the hardness of the system to a laser threat. It was concluded from these tests that the GDS is basically prototypic of a flight design; all components necessary for satisfactory operation were demonstrated successfully at the system level; over 11,000 total h of operation without any component failure attested to the inherent reliability of this type of system; and some further development is required, specifically in the area of performance

  6. Technology verification phase. Dynamic isotope power system. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Halsey, D.G.

    1982-03-10

    The Phase I requirements of the Kilowatt Isotope Power System (KIPS) program were to make a detailed Flight System Conceptual Design (FSCD) for an isotope fueled organic Rankine cycle power system and to build and test a Ground Demonstration System (GDS) which simulated as closely as possible the operational characteristics of the FSCD. The activities and results of Phase II, the Technology Verification Phase, of the program are reported. The objectives of this phase were to increase system efficiency to 18.1% by component development, to demonstrate system reliability by a 5000 h endurance test and to update the flight system design. During Phase II, system performance was improved from 15.1% to 16.6%, an endurance test of 2000 h was performed while the flight design analysis was limited to a study of the General Purpose Heat Source, a study of the regenerator manufacturing technique and analysis of the hardness of the system to a laser threat. It was concluded from these tests that the GDS is basically prototypic of a flight design; all components necessary for satisfactory operation were demonstrated successfully at the system level; over 11,000 total h of operation without any component failure attested to the inherent reliability of this type of system; and some further development is required, specifically in the area of performance. (LCL)

  7. High dynamic range isotope ratio measurements using an analog electron multiplier

    Czech Academy of Sciences Publication Activity Database

    Williams, P.; Lorinčík, Jan; Franzreb, K.; Herwig, R.

    2013-01-01

    Roč. 45, č. 1 (2013), s. 549-552 ISSN 0142-2421 R&D Projects: GA MŠk ME 894 Institutional support: RVO:67985882 Keywords : Isotope ratios * electron multiplier * dynamic range Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.393, year: 2013

  8. Stable isotope-resolved analysis with quantitative dissolution dynamic nuclear polarization

    DEFF Research Database (Denmark)

    Lerche, Mathilde Hauge; Yigit, Demet; Frahm, Anne Birk

    2018-01-01

    Metabolite profiles and their isotopomer distributions can be studied non-invasively in complex mixtures with NMR. The advent of dissolution Dynamic Nuclear Polarization (dDNP) and isotope enrichment add sensitivity and resolution to such met-abolic studies. Metabolic pathways and networks can be...

  9. Isotope investigation on groundwater recharge and dynamics in shallow and deep alluvial aquifers of southwest Punjab.

    Science.gov (United States)

    Keesari, Tirumalesh; Sharma, Diana A; Rishi, Madhuri S; Pant, Diksha; Mohokar, Hemant V; Jaryal, Ajay Kumar; Sinha, U K

    2017-11-01

    Groundwater samples collected from the alluvial aquifers of southwest Punjab, both shallow and deep zones were measured for environmental tritium ( 3 H) and stable isotopes ( 2 H and 18 O) to evaluate the source of recharge and aquifer dynamics. The shallow groundwater shows wide variation in isotopic signature (δ 18 O: -11.3 to -5.0‰) reflecting multiple sources of recharge. The average isotopic signature of shallow groundwaters (δ 18 O: -6.73 ± 1.03‰) is similar to that of local precipitation (-6.98 ± 1.66‰) indicating local precipitation contributes to a large extent compared to other sources. Other sources have isotopically distinct signatures due to either high altitude recharge (canal sources) or evaporative enrichment (irrigation return flow). Deep groundwater shows relatively depleted isotopic signature (δ 18 O: -8.6‰) and doesn't show any evaporation effect as compared to shallow zone indicating recharge from precipitation occurring at relatively higher altitudes. Environmental tritium indicates that both shallow ( 3 H: 5 - 10 T.U.) and deeper zone ( 3 H: 1.5 - 2.5 T.U.) groundwaters are modern. In general the inter-aquifer connections seem to be unlikely except a few places. Environmental isotope data suggests that shallow groundwater is dynamic, local and prone to changes in land use patterns while deep zone water is derived from distant sources, less dynamic and not impacted by surface manifestations. A conceptual groundwater flow diagram is presented. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Shape mixing dynamics in the low-lying states of proton-rich Kr isotopes

    International Nuclear Information System (INIS)

    Sato, Koichi; Hinohara, Nobuo

    2011-01-01

    We study the oblate-prolate shape mixing in the low-lying states of proton-rich Kr isotopes using the five-dimensional quadrupole collective Hamiltonian. The collective Hamiltonian is derived microscopically by means of the CHFB (constrained Hartree-Fock-Bogoliubov) + Local QRPA (quasiparticle random phase approximation) method, which we have developed recently on the basis of the adiabatic self-consistent collective coordinate method. The results of the numerical calculation show the importance of large-amplitude collective vibrations in the triaxial shape degree of freedom and rotational effects on the oblate-prolate shape mixing dynamics in the low-lying states of these isotopes.

  11. On dewetting dynamics of solid films of hydrogen isotopes and its influence on tritium β spectroscopy

    International Nuclear Information System (INIS)

    Fleischmann, L.; Bonn, J.; Bornschein, B.; Otten, E.W.; Przyrembel, M.; Weinheimer, Ch.

    2000-01-01

    The dewetting dynamics of solid films of hydrogen isotopes, quench-condensed on a graphite substrate, was measured at various temperatures below desorption by observing the stray light from the film. A schematic model describing the dewetting process by surface diffusion is presented, which agrees qualitatively with our data. The activation energies of different hydrogen isotopes for surface diffusion were determined. The time constant for dewetting of a quench-condensed T 2 film at the working temperature of 1.86 K of the mainz neutrino mass experiment was extrapolated. (orig.)

  12. Dynamic Isotope Power System: technology verification phase, program plan, 1 October 1978

    International Nuclear Information System (INIS)

    1979-01-01

    The technology verification phase program plan of the Dynamic Isotope Power System (DIPS) project is presented. DIPS is a project to develop a 0.5 to 2.0 kW power system for spacecraft using an isotope heat source and a closed-cycle Rankine power-system with an organic working fluid. The technology verification phase's purposes are to increase the system efficiency to over 18%, to demonstrate system reliability, and to provide an estimate for flight test scheduling. Progress toward these goals is reported

  13. Automotive Stirling Engine Development Program

    Science.gov (United States)

    Nightingale, N.; Ernst, W.; Richey, A.; Simetkosky, M.; Smith, G.; Antonelli, M. (Editor)

    1983-01-01

    Mod I engine testing and test results, the test of a Mod I engine in the United States, Mod I engine characterization and analysis, Mod I Transient Test Bed fuel economy, Mod I-A engine performance are discussed. Stirling engine reference engine manufacturing and reduced size studies, components and subsystems, and the study and test of low-cost casting alloys are also covered. The overall program philosophy is outlined, and data and results are presented.

  14. Automotive Stirling engine development program: A success

    Science.gov (United States)

    Tabata, W. K.

    1987-01-01

    The original 5-yr Automotive Stirling Engine Development Program has been extended to 10 years due to reduced annual funding levels. With an estimated completion date of April 1988, the technical achievements and the prospectives of meeting the original program objectives are reviewed. Various other applications of this developed Stirling engine technology are also discussed.

  15. Demonstration Experiments with a Stirling Engine.

    Science.gov (United States)

    Deacon, Christopher G.; And Others

    1994-01-01

    Describes an investigation with the primary purpose of allowing students to generate and interpret a pressure/volume diagram of a Stirling engine. Explains how the Stirling engine can be used to demonstrate the principles of operation of a refrigerator and a heat pump. (DDR)

  16. Isotopes reveal dynamics of groundwater system in Region 2, Philippines

    International Nuclear Information System (INIS)

    Mendoza, N.D.S.; Racadio, C.D.T.; Sucgang, R.J.; Castañeda, S.S.

    2015-01-01

    Steady economic and population growth in Region 2 could lead to an exponential increase freshwater demand. However, region 2’s main source of freshwater is groundwater and, if not checked and managed carefully, it could eventually affect the availability and sustainability of groundwater resources in Water Resource Region 2 (WRR2). Stable isotopes along with Tritium analysis in different water bodies such as rain, shallow and deep groundwater, springs and rivers were used to gain insight about the hydrological process in WRR2. Local meteoric water line for WRR2 was found to be δ2H = 8.6 δ 18O + 13.3 (r = 0.98). The estimated annual mean, which was used as a local index was to be -7.1 ‰ δ “1”8O_v_s_m_o_w_-_s_l_a_p. Shallow wells (20 – 30 m) and production wells (multi-screened wells, max depth of about 100 – 120m) were found to exhibit relatively more enrich than the index (i.e. -7.1‰) with means of -6.2 ‰ (s.d. 1.1‰, n=19) and -6.6 ‰ (s.d. 0.9; n= 151), respectively, which was an indication of infiltration of evaporated waters possibly from river and irrigation waters. Tritium analysis were done on selected sites to identify groundwater age (GWA) and possibly track the flow of groundwater from recharge areas (such as in Nueva Vizcaya, GWA = 3 years) down to the plains (Tuguegarao, GWA range from 9 to 30 years). Groundwaters drawn from production wells in Tuguegarao with ages of more than 30 years suggest that more fraction of water were being drawn from deeper aquifers. Such scenario could mean that were less water in shallow aquifers (e.g. 30 m deep) which are typically younger in age than waters found at deeper aquifers (e.g. 100 m deep). (author)

  17. Stirling engine design manual, 2nd edition

    Science.gov (United States)

    Martini, W. R.

    1983-01-01

    This manual is intended to serve as an introduction to Stirling cycle heat engines, as a key to the available literature on Stirling engines and to identify nonproprietary Stirling engine design methodologies. Two different fully described Stirling engines are discussed. Engine design methods are categorized as first order, second order, and third order with increased order number indicating increased complexity. FORTRAN programs are listed for both an isothermal second order design program and an adiabatic second order design program. Third order methods are explained and enumerated. In this second edition of the manual the references are updated. A revised personal and corporate author index is given and an expanded directory lists over 80 individuals and companies active in Stirling engines.

  18. CHP from Updraft Gasifier and Stirling Engine

    DEFF Research Database (Denmark)

    Jensen, N.; Werling, J.; Carlsen, Henrik

    2002-01-01

    The combination of thermal gasification with a Stirling engine is an interesting concept for use in small combined heat and power plants based on biomass. By combining the two technologies a synergism can potentially be achieved. Technical problems, e.g. gas cleaning and fouling of the Stirling...... engine heat exchanger, can be eliminated and the overall electric efficiency of the system can be improved. At the Technical University of Denmark a Stirling engine fueled by gasification gas has been developed. In this engine the combustion system and the geometry of the hot heat exchanger...... of the Stirling engine has been adapted to the use of a gas with a low specific energy content and a high content of tar and particles. In the spring of 2001 a demonstration plant has been built in the western part of Denmark where this Stirling engine is combined with an updraft gasifier. A mathematical...

  19. Downsizing assessment of automotive Stirling engines

    Science.gov (United States)

    Knoll, R. H.; Tew, R. C., Jr.; Klann, J. L.

    1983-01-01

    A 67 kW (90 hp) Stirling engine design, sized for use in a 1984 1440 kg (3170 lb) automobile was the focal point for developing automotive Stirling engine technology. Since recent trends are towards lighter vehicles, an assessment was made of the applicability of the Stirling technology being developed for smaller, lower power engines. Using both the Philips scaling laws and a Lewis Research Center (Lewis) Stirling engine performance code, dimensional and performance characteristics were determined for a 26 kW (35 hp) and a 37 kW (50 hp) engine for use in a nominal 907 kg (2000 lb) vehicle. Key engine elements were sized and stressed and mechanical layouts were made to ensure mechanical fit and integrity of the engines. Fuel economy estimates indicated that the Stirling engine would maintain a 30 to 45 percent fuel economy advantage comparable spark ignition and diesel powered vehicles in the 1984 period.

  20. Isotope techniques in non-destructive testing of dynamic systems

    International Nuclear Information System (INIS)

    Singh, Gursharan; Pant, H.J.

    1996-01-01

    A few applications of gamma scanning and radiotracer techniques for Non-destructive Testing (NDT) of dynamic systems in chemical and petrochemical industries are briefly discussed in this paper. Examples of gamma scanning inspections carried out for troubleshooting of various types of columns such as vacuum, extraction, separator and rectifier, with trays and packed beds and having diameters from 1 meter to 8.4 meters are given. Radiotracer applications for Residence Time Distribution (RTD) studies on different systems like an aniline production reactor in a chemical industry and a laboratory scale solid-liquid fluidized bed column are mentioned. (author)

  1. Free-piston Stirling technology for space power

    Science.gov (United States)

    Slaby, Jack G.

    1989-01-01

    An overview is presented of the NASA Lewis Research Center free-piston Stirling engine activities directed toward space power. This work is being carried out under NASA's new Civil Space Technology Initiative (CSTI). The overall goal of CSTI's High Capacity Power element is to develop the technology base needed to meet the long duration, high capacity power requirements for future NASA space missions. The Stirling cycle offers an attractive power conversion concept for space power needs. Discussed here is the completion of the Space Power Demonstrator Engine (SPDE) testing-culminating in the generation of 25 kW of engine power from a dynamically-balanced opposed-piston Stirling engine at a temperature ratio of 2.0. Engine efficiency was approximately 22 percent. The SPDE recently has been divided into two separate single-cylinder engines, called Space Power Research Engine (SPRE), that now serve as test beds for the evaluation of key technology disciplines. These disciplines include hydrodynamic gas bearings, high-efficiency linear alternators, space qualified heat pipe heat exchangers, oscillating flow code validation, and engine loss understanding.

  2. The Stirling engine mechanism optimization

    Directory of Open Access Journals (Sweden)

    Jiří Podešva

    2016-03-01

    Full Text Available A special type of the gas engine with external combustion is called Stirling engine. The mechanism has two pistons with two volumes inside. The pistons are connected together through cooler, regenerator and warmer. The engine effectivity depends on the piston movement behaviour. The usual sinusoidal time curve leads to low effectiveness. The quick movement from lower to upper position with a certain delay in both top and bottom dead centres is more effective. The paper deals with three types of mechanisms, analyzing the piston movement, and their behavior. Special emphasize is taken to the piston movement regime.

  3. Free-piston Stirling component test power converter test results and potential Stirling applications

    Science.gov (United States)

    Dochat, G. R.

    1992-01-01

    As the principal contractor to NASA-Lewis Research Center, Mechanical Technology Incorporated is under contract to develop free-piston Stirling power converters in the context of the competitive multiyear Space Stirling Technology Program. The first generation Stirling power converter, the component test power converter (CTPC) initiated cold end testing in 1991, with hot testing scheduled for summer of 1992. This paper reviews the test progress of the CTPC and discusses the potential of Stirling technology for various potential missions at given point designs of 250 watts, 2500 watts, and 25,000 watts.

  4. Preliminary designs for 25 kWe advanced Stirling conversion systems for dish electric applications

    Science.gov (United States)

    Shaltens, Richard K.; Schreiber, Jeffrey G.

    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 engines for terrestrial applications. The Stirling engine also has the potential to meet DOE's performance and cost goals. The NASA Lewis Research Center is conducting Stirling engine technology development activities directed toward a dynamic power source for space applications. Space power systems requirements include high reliability, very long life, low vibration and high efficiency. The free-piston Stirling engine has the potential for future high power space conversion systems, either nuclear or solar powered. Although both applications appear to be quite different, their requirements complement each other. Preliminary designs feature a free-piston Stirling engine, a liquid metal heat transport system, and a means to provide nominally 25 kW electric power to a utility grid while meeting DOE's performance and long term cost goals. The Cummins design incorporates a linear alternator to provide the electrical output, while the STC design generates electrical power indirectly through a hydraulic pump/motor coupled to an induction generator. Both designs for the ASCS's will use technology which can reasonably be expected to be available in the early 1990's.

  5. Variable displacement alpha-type Stirling engine

    Science.gov (United States)

    Homutescu, V. M.; Bălănescu, D. T.; Panaite, C. E.; Atanasiu, M. V.

    2016-08-01

    The basic design and construction of an alpha-type Stirling engine with on load variable displacement is presented. The variable displacement is obtained through a planar quadrilateral linkage with one on load movable ground link. The physico-mathematical model used for analyzing the variable displacement alpha-type Stirling engine behavior is an isothermal model that takes into account the real movement of the pistons. Performances and power adjustment capabilities of such alpha-type Stirling engine are calculated and analyzed. An exemplification through the use of the numerical simulation was performed in this regard.

  6. Idealization of The Real Stirling Cycle

    Directory of Open Access Journals (Sweden)

    Červenka Libor

    2016-12-01

    Full Text Available The paper presents a potential idealization of the real Stirling cycle. This idealization is performed by modifying the piston movement corresponding to the ideal Stirling cycle. The focus is on the cycle thermodynamics with respect to the indicated efficiency and indicated power. A detailed 1-D simulation model of a Stirling engine is used as a tool for this assessment. The model includes real non-zero volumes of heater, regenerator, cooler and connecting pipe. The model is created in the GT Power commercial simulation software.

  7. Rotary Stirling-Cycle Engine And Generator

    Science.gov (United States)

    Chandler, Joseph A.

    1990-01-01

    Proposed electric-power generator comprises three motor generators coordinated by microprocessor and driven by rotary Stirling-cycle heat engine. Combination offers thermodynamic efficiency of Stirling cycle, relatively low vibration, and automatic adjustment of operating parameters to suit changing load on generator. Rotary Stirling cycle engine converts heat to power via compression and expansion of working gas between three pairs of rotary pistons on three concentric shafts in phased motion. Three motor/generators each connected to one of concentric shafts, can alternately move and be moved by pistons. Microprocessor coordinates their operation, including switching between motor and generator modes at appropriate times during each cycle.

  8. Advanced Stirling Convertor Testing at GRC

    Science.gov (United States)

    Schifer, Nick; Oriti, Salvatore M.

    2013-01-01

    NASA Glenn Research Center (GRC) has been supporting development of the Advanced Stirling Radioisotope Generator (ASRG) since 2006. A key element of the ASRG project is providing life, reliability, and performance testing of the Advanced Stirling Convertor (ASC). The latest version of the ASC, deemed ASC-E3, is of a design identical to the forthcoming flight convertors. The first pair of ASC-E3 units was delivered in December 2012. GRC has begun the process of adding these units to the catalog of ongoing Stirling convertor operation. This process includes performance verification, which examines the data from various tests to validate the convertors performance to the product specification.

  9. Automotive Stirling Engine Development Project

    Science.gov (United States)

    Ernst, William D.; Shaltens, Richard K.

    1997-01-01

    The development and verification of automotive Stirling engine (ASE) component and system technology is described as it evolved through two experimental engine designs: the Mod 1 and the Mod 2. Engine operation and performance and endurance test results for the Mod 1 are summarized. Mod 2 engine and component development progress is traced from the original design through hardware development, laboratory test, and vehicle installation. More than 21,000 hr of testing were accomplished, including 4800 hr with vehicles that were driven more dm 59,000 miles. Mod 2 engine dynamometer tests demonstrated that the engine system configuration had accomplished its performance goals for power (60 kW) and efficiency (38.5%) to within a few percent. Tests with the Mod 2 engine installed in a delivery van demonstrated combined metro-highway fuel economy improvements consistent with engine performance goals and the potential for low emission levels. A modified version of the Mod 2 has been identified as a manufacturable design for an ASE. As part of the ASE project, the Industry Test and Evaluation Program (ITEP), NASA Technology Utilization (TU) project, and the industry-funded Stirling Natural Gas Engine program were undertaken to transfer ASE technology to end users. The results of these technology transfer efforts are also summarized.

  10. Continuing Development for Free-Piston Stirling Space Power Systems

    Science.gov (United States)

    Peterson, Allen A.; Qiu, Songgang; Redinger, Darin L.; Augenblick, John E.; Petersen, Stephen L.

    2004-02-01

    Long-life radioisotope power generators based on free-piston Stirling engines are an energy-conversion solution for future space applications. The high efficiency of Stirling machines makes them more attractive than the thermoelectric generators currently used in space. Stirling Technology Company (STC) has been developing free-piston Stirling machines for over 30 years, and its family of Stirling generators is ideally suited for reliable, maintenance-free operation. This paper describes recent progress and status of the STC RemoteGen™ 55 W-class Stirling generator (RG-55), presents an overview of recent testing, and discusses how the technology demonstration design has evolved toward space-qualified hardware.

  11. Isotope effect on hydrated electron relaxation dynamics studied with time-resolved liquid jet photoelectron spectroscopy

    Science.gov (United States)

    Elkins, Madeline H.; Williams, Holly L.; Neumark, Daniel M.

    2016-05-01

    The excited state relaxation dynamics of the solvated electron in H2O and D2O are investigated using time-resolved photoelectron spectroscopy in a liquid microjet. The data show that the initial excited state decays on a time scale of 75 ± 12 fs in H2O and 102 ± 8 fs in D2O, followed by slower relaxation on time scales of 400 ± 70 fs and 390 ± 70 fs that are isotopically invariant within the precision of our measurements. Based on the time evolution of the transient signals, the faster and slower time constants are assigned to p → s internal conversion (IC) of the hydrated electron and relaxation on the ground electronic state, respectively. This assignment is consistent with the non-adiabatic mechanism for relaxation of the hydrated electron and yields an isotope effect of 1.4 ± 0.2 for IC of the hydrated electron.

  12. Numerical simulation for the design analysis of kinematic Stirling engines

    International Nuclear Information System (INIS)

    Araoz, Joseph A.; Salomon, Marianne; Alejo, Lucio; Fransson, Torsten H.

    2015-01-01

    Highlights: • A thermodynamic analysis for kinematic Stirling engines was presented. • The analysis integrated thermal, mechanical and thermodynamic interactions. • The analyses considered geometrical and operational parameters. • The results allowed to map the performance of the engine. • The analysis allow the design assessment of Stirling engines. - Abstract: The Stirling engine is a closed-cycle regenerative system that presents good theoretical properties. These include a high thermodynamic efficiency, low emissions levels thanks to a controlled external heat source, and multi-fuel capability among others. However, the performance of actual prototypes largely differs from the mentioned theoretical potential. Actual engine prototypes present low electrical power outputs and high energy losses. These are mainly attributed to the complex interaction between the different components of the engine, and the challenging heat transfer and fluid dynamics requirements. Furthermore, the integration of the engine into decentralized energy systems such as the Combined Heat and Power systems (CHP) entails additional complications. These has increased the need for engineering tools that could assess design improvements, considering a broader range of parameters that would influence the engine performance when integrated within overall systems. Following this trend, the current work aimed to implement an analysis that could integrate the thermodynamics, and the thermal and mechanical interactions that influence the performance of kinematic Stirling engines. In particular for their use in Combined Heat and Power systems. The mentioned analysis was applied for the study of an engine prototype that presented very low experimental performance. The numerical methodology was selected for the identification of possible causes that limited the performance. This analysis is based on a second order Stirling engine model that was previously developed and validated. The

  13. Raytheon Stirling/pulse Tube Cryocooler Development

    Science.gov (United States)

    Kirkconnell, C. S.; Hon, R. C.; Kesler, C. H.; Roberts, T.

    2008-03-01

    The first generation flight-design Stirling/pulse tube "hybrid" two-stage cryocooler has entered initial performance and environmental testing. The status and early results of the testing are presented. Numerous improvements have been implemented as compared to the preceding brassboard versions to improve performance, extend life, and enhance launch survivability. This has largely been accomplished by incorporating successful flight-design features from the Raytheon Stirling one-stage cryocooler product line. These design improvements are described. In parallel with these mechanical cryocooler development efforts, a third generation electronics module is being developed that will support hybrid Stirling/pulse tube and Stirling cryocoolers. Improvements relative to the second generation design relate to improved radiation hardness, reduced parts count, and improved vibration cancellation capability. Progress on the electronics is also presented.

  14. Automotive Stirling engine: Mod 2 design report

    Science.gov (United States)

    Nightingale, Noel P.

    1986-01-01

    The design of an automotive Stirling engine that achieves the superior fuel economy potential of the Stirling cycle is described. As the culmination of a 9-yr development program, this engine, designated the Mod 2, also nullifies arguments that Stirling engines are heavy, expensive, unreliable, demonstrating poor performance. Installed in a General Motors Chevrolet Celebrity car, this engine has a predicted combined fuel economy on unleaded gasoline of 17.5 km/l (41 mpg)- a value 50% above the current vehicle fleet average. The Mod 2 Stirling engine is a four-cylinder V-drive design with a single crankshaft. The engine is also equipped with all the controls and auxiliaries necessary for automotive operation.

  15. Stirling convertor performance mapping test results

    Science.gov (United States)

    Qiu, Songgang; Peterson, Allen A.; White, Maurice A.; Faultersack, Franklyn; Redinger, Darin L.; Petersen, Stephen L.

    2002-01-01

    The Department of Energy (DOE) has selected Free-Piston Stirling Convertors as a technology for future advanced radioisotope space power systems. In August 2000, DOE awarded competitive Phase I, Stirling Radioisotope Generator (SRG) power system integration contracts to three major aerospace contractors, resulting in SRG conceptual designs in February 2001. All three contractors based their designs on the Technology Demonstration Convertor (TDC) developed by Stirling Technology Company (STC) for DOE. The contract award to a single system integration contractor for Phases II and III of the SRG program is anticipated in late 2001. The first potential SRG mission is targeted for a Mars rover. Recent TDC performance data are provided in this paper, together with predictions from Stirling simulation models. .

  16. Simple and Clear Proofs of Stirling's Formula

    Science.gov (United States)

    Niizeki, Shozo; Araki, Makoto

    2010-01-01

    The purpose of our article is to show two simpler and clearer methods of proving Stirling's formula than the traditional and conventional ones. The distinction of our method is to use the simple trapezoidal formula.

  17. Alternative thermodynamic cycle for the Stirling machine

    Science.gov (United States)

    Romanelli, Alejandro

    2017-12-01

    We develop an alternative thermodynamic cycle for the Stirling machine, where the polytropic process plays a central role. Analytical expressions for pressure and temperatures of the working gas are obtained as a function of the volume and the parameter that characterizes the polytropic process. This approach achieves closer agreement with the experimental pressure-volume diagram and can be adapted to any type of Stirling engine.

  18. Recent Stirling engine loss - understanding results

    International Nuclear Information System (INIS)

    Tew, R.C.; Thieme, L.G.; Dudenhoefer, J.E.

    1994-01-01

    For several years, the National Aeronautics and Space Administration and other US Government agencies have been funding experimental and analytical efforts to improve the understanding of Stirling thermodynamic losses. NASA's objective is to improve Stirling engine design capability to support the development of new engines for space power. An overview of these efforts was last given at the 1988 IECEC. Recent results of this research are reviewed

  19. Inhibition delay increases neural network capacity through Stirling transform

    Science.gov (United States)

    Nogaret, Alain; King, Alastair

    2018-03-01

    Inhibitory neural networks are found to encode high volumes of information through delayed inhibition. We show that inhibition delay increases storage capacity through a Stirling transform of the minimum capacity which stabilizes locally coherent oscillations. We obtain both the exact and asymptotic formulas for the total number of dynamic attractors. Our results predict a (ln2) -N-fold increase in capacity for an N -neuron network and demonstrate high-density associative memories which host a maximum number of oscillations in analog neural devices.

  20. Use of isotope techniques in lake dynamics investigations. Proceedings of a final research co-ordination meeting

    International Nuclear Information System (INIS)

    2001-03-01

    The Co-ordinated Research Programme (CRP) on the Use of Isotope Techniques in Lake Dynamics Investigations was launched with the aim of assessing the potential of environmental isotope techniques in studying the dynamics of surface water bodies and related problems such as: dynamics of solutes; sediment focusing; establishment of water balance components; vulnerability to pollution. The CRP enabled a number of isotope and geochemical studies to be carried out on small and large water bodies, with the general aim of understanding of the dynamics of these systems under the growing anthropogenic influence. This publication is a compilation of the papers presented at the final Research Co-ordination Meeting (RCM) held in Rehovot, Israel, from 10 to 13 March 1997. Individual contributions have been indexed separately

  1. Research on the groundwater flow dynamics of Lamas basin by isotope methods

    International Nuclear Information System (INIS)

    Onhon, E.; Sayin, M.; Basaran, N.; Can, D.; Yuce, G.; Pelen, N.; Kaplan, A.

    1996-01-01

    The main objective of Lamas Project is to define the relation between the recharge to highlands and the discharge realized by the springs along the Mediterranean coast and thus assist to the development of karst water resources by preparing a dependable evaluation of the water budget. The investigation area covers almost 4400 square kilometers where the elevation rises from 0 to 2900 m. Lamas is the main river crossing the area from northwest to southeast with a yield between 13.48 to 2.77 cu.m/s. the karstification in the area has at least reached 300 m in depth. The water samples were collected from 16 springs, 3 drilled wells, stream and two meteorological stations, to define the groundwater dynamics and investigate the relation between the sampling points and to assist the establishment of an evaluation in isotope hydrology. By taking into consideration the unmeasured discharges along the coast line, the infiltration from the precipitation is approximately 50-60 %. The water in the aquifer is isotopically affected by the infiltration of low altitude precipitation. The hydrogeological and isotope hydrology investigations have reached the conclusions that the karst water resources can be developed by drilling of deep wells near the karst springs. (author). 9 refs, 7 figs, 2 tabs

  2. Self-pressurizing Stirling engine

    Science.gov (United States)

    Bennett, Charles L.

    2010-10-12

    A solar thermal powered aircraft powered by heat energy from the sun. A heat engine, such as a Stirling engine, is carried by the aircraft body for producing power for a propulsion mechanism, such as a propeller. The heat engine has a thermal battery in thermal contact with it so that heat is supplied from the thermal battery. A solar concentrator, such as reflective parabolic trough, is movably connected to an optically transparent section of the aircraft body for receiving and concentrating solar energy from within the aircraft. Concentrated solar energy is collected by a heat collection and transport conduit, and heat transported to the thermal battery. A solar tracker includes a heliostat for determining optimal alignment with the sun, and a drive motor actuating the solar concentrator into optimal alignment with the sun based on a determination by the heliostat.

  3. Scaling laws for free piston Stirling engine design: Benefits and challenges of miniaturization

    International Nuclear Information System (INIS)

    Formosa, Fabien; Fréchette, Luc G.

    2013-01-01

    This work explores the scaling effects for FPSE (free piston Stirling engines), which are known for their simple architecture and potentially high thermodynamic performances. Scaling laws are given and their potential for miniaturization is highlighted. A simple model which allows the design of the geometrical parameters of the heat exchangers, the regenerator and the masses of the pistons is proposed. It is based on the definition of six characteristic dimensionless groups. They are derived from the physics underlying the behavior of the free piston Stirling machine and their relevancy is backed up by comparisons between documented Stirling engines from the literature. Keeping constant values for each group throughout the scaling range theoretically ensures constant performance. The main losses of Stirling engine (heat conduction loss, reheat loss in the regenerator, pressure drop and gas-spring hysteresis) can be expressed as a function of the geometrical and operating parameters. Additionally, the consequences of leakage due to the manufacturing precision of pistons architectures are underlined. From the proposed scaling laws, potential power and efficiency of Stirling cycle engines at a millimeter scale can be anticipated. It appears that the power density increases with miniaturization. It is also shown that the dynamic masses related to the engine size are increased when scaling down and that the gap leakage presents the highest detrimental effects on the efficiency. These results call for dedicated architectures for micro-engines. - Highlights: • Similitude strategy is applied to Stirling engines and allows preliminary design. • New scaling laws are derived. • The power density can be increased with miniaturization. • The gap between the piston and casing is highly detrimental to the performances. • High engine operating pressure is required when miniaturizing

  4. Improving Free-Piston Stirling Engine Specific Power

    Science.gov (United States)

    Briggs, Maxwell H.

    2015-01-01

    This work uses analytical methods to demonstrate the potential benefits of optimizing piston and/or displacer motion in a Stirling engine. Isothermal analysis was used to show the potential benefits of ideal motion in ideal Stirling engines. Nodal analysis is used to show that ideal piston and displacer waveforms are not optimal in real Stirling engines. Constrained optimization was used to identify piston and displacer waveforms that increase Stirling engine specific power.

  5. Demonstration of a free piston Stirling engine driven linear alternator system. Annual report

    International Nuclear Information System (INIS)

    1978-01-01

    The objective of the program is to develop a 2 kW Free Piston Stirling Engine/Linear Alternator Energy Conversion System for an isotopic heat source with a greater than 30% overall efficiency. The work was broken up into two phases. Phase I demonstrated the feasibility of the energy conversion system through analysis and experimental testing of the individual components. Phase II is a two-year effort to design, fabricate, and test a prototype demonstrator energy conversion system. The reprt documents the work performed during October 1976 through September 1977, the first year of Phase II. Details of the tasks are presented in five major sections: (1) Linear Alternator Development; (2) Engine/Alternator System Demonstration; (3) Demonstrator Preliminary Design; (4) Demonstrator Detailed Design; and (5) Development of Free Piston Stirling Engine Computer Simulation

  6. Test results and commercialization plans for long life Stirling generators

    International Nuclear Information System (INIS)

    Erbeznik, R.M.; White, M.A.

    1996-01-01

    Many optimistic predictions regarding commercialization of Stirling engines have been announced over the years, but to date no real successes have emerged. STC is excited to announce the availability of beta prototypes for its RemoteGen trademark family of free-piston Stirling generators. STC is working with suppliers, manufacturers, and beta customers to commercialize the RemoteGen family of generators. STC is proving that these machines overcome previously inhibiting barriers by providing long life, high reliability, cost effective mass production, and market relevance. Stirling power generators are generally acknowledged to offer much higher conversion efficiencies than direct energy conversion systems. Life and reliability, on the other hand, are generally considered superior for direct conversion systems, as established by the exceptional endurance records (though with degradation) for thermoelectric (TE) and photovoltaic (PV) systems. STC's unique approaches combine dynamic system efficiency with static system reliability. The RemoteGen family presently includes a 10-watt RG-10, a 350-watt RG-350, and with 1-kW and 3-kW sizes planned for the future. They all use the same basic configuration with flexure bearings, clearance seals, and moving iron linear alternators. The third generation RG-10 has entered limited production with a radioisotope-fueled version, and a niche market for a propane-fueled version has been identified. Market analysis has led STC to focus on early commercial production of the RG-350. The linear alternator power module portion of the RG-350 is also used in its sister BeCool trademark family of coolers as the linear motor. By using a common power module, both programs will benefit by each other's commercialization efforts. The technology behind the RemoteGen generators, test results, and plans for commercialization are described in this paper

  7. Advanced Stirling Convertor Durability Testing: Plans and Interim Results

    Science.gov (United States)

    Meer, David W.; Oriti, Salvatore M.

    2012-01-01

    The U.S. Department of Energy (DOE), Lockheed Martin Corporation (LM), and NASA Glenn Research Center (GRC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. In support of this program, GRC has been involved in testing Stirling convertors, including the Advanced Stirling Convertor (ASC), for use in the ASRG. This testing includes electromagnetic interference/compatibility (EMI/EMC), structural dynamics, advanced materials, organics, and unattended extended operation. The purpose of the durability tests is to experimentally demonstrate the margins in the ASC design. Due to the high value of the hardware, previous ASC tests focused on establishing baseline performance of the convertors within the nominal operating conditions. The durability tests present the first planned extension of the operating conditions into regions beyond those intended to meet the product spec, where the possibility exists of lateral contact, overstroke, or over-temperature events. These tests are not intended to cause damage that would shorten the life of the convertors, so they can transition into extended operation at the conclusion of the tests. This paper describes the four tests included in the durability test sequence: 1) start/stop cycling, 2) exposure to constant acceleration in the lateral and axial directions, 3) random vibration at increased piston amplitude to induce contact events, and 4) overstroke testing to simulate potential failures during processing or during the mission life where contact events could occur. The paper also summarizes the analysis and simulation used to predict the results of each of these tests.

  8. Interplay of community dynamics, temperature, and productivity on the hydrogen isotope signatures of lipid biomarkers

    Directory of Open Access Journals (Sweden)

    S. N. Ladd

    2017-09-01

    Full Text Available The hydrogen isotopic composition (δ2H of lipid biomarkers has diverse applications in the fields of paleoclimatology, biogeochemistry, and microbial community dynamics. Large changes in hydrogen isotope fractionation have been observed among microbes with differing core metabolisms, while environmental factors including temperature and nutrient availability can affect isotope fractionation by photoautotrophs. Much effort has gone into studying these effects under laboratory conditions with single species cultures. Moving beyond controlled environments and quantifying the natural extent of these changes in freshwater lacustrine settings and identifying their causes is essential for robust application of δ2H values of common short-chain fatty acids as a proxy of net community metabolism and of phytoplankton-specific biomarkers as a paleohydrologic proxy. This work targets the effect of community dynamics, temperature, and productivity on 2H∕1H fractionation in lipid biomarkers through a comparative time series in two central Swiss lakes: eutrophic Lake Greifen and oligotrophic Lake Lucerne. Particulate organic matter was collected from surface waters at six time points throughout the spring and summer of 2015, and δ2H values of short-chain fatty acids, as well as chlorophyll-derived phytol and the diatom biomarker brassicasterol, were measured. We paired these measurements with in situ incubations conducted with NaH13CO3, which were used to calculate the production rates of individual lipids in lake surface water. As algal productivity increased from April to June, net discrimination against 2H in Lake Greifen increased by as much as 148 ‰ for individual fatty acids. During the same time period in Lake Lucerne, net discrimination against 2H increased by as much as 58 ‰ for individual fatty acids. A large portion of this signal is likely due to a greater proportion of heterotrophically derived fatty acids in the winter and early

  9. James Stirling Regionalismo y modernidad

    Directory of Open Access Journals (Sweden)

    Javier de Esteban Garbayo

    2015-05-01

    Full Text Available ResumenEn los años treinta, la arquitectura moderna se había introducido en los más remotos lugares del mundo enfrentándose con la infinita idiosincrasia de lo local, y al mismo tiempo, el arquitecto, sintiendo las limitaciones de su estilo e intentando ampliar su vocabulario, se embarcó en un proceso de difusión, asimilación y personalización.La idea de una renovada época después de la posguerra británica, sería compartida por una joven generación de arquitectos con el fin de encontrar una nueva forma de modernidad.Si en sus proyectos domésticos de mediados de los cincuenta, James Stirling partió de una aproximación al regionalismo y a la 'tradición funcional' con el fin de renovar el lenguaje moderno, no abandonaría la idea 'programática' inicial de entender la arquitectura desde una consistencia formal y una lógica que combinaba 'una síntesis común del pasado reciente y una certera actitud hacia el futuro'. AbstractThirties, modern architecture had percolated into remote corners of the world, encountering the infinite idiosyncrasies of locality, and, at the same time, Architects, feelings the limitations of their style and becoming intent upon extending their vocabulary, embarked upon a process of diffusion, assimilation and personalitation.The idea of a renewed period after British postwar, was shared for a new young architects generationto find a new way of modernity.While in his mid fifties housing projects, James Stirling approached to 'regionalism' and 'the functional tradition' to renew the modern language, he wouldn't reject the programmatic idea to understand architecture from a logic and formal consistency that combine 'a common synthesis of the recent past and a certain attitude toward the future'.

  10. Nitrate denitrification with nitrite or nitrous oxide as intermediate products: Stoichiometry, kinetics and dynamics of stable isotope signatures.

    Science.gov (United States)

    Vavilin, V A; Rytov, S V

    2015-09-01

    A kinetic analysis of nitrate denitrification by a single or two species of denitrifying bacteria with glucose or ethanol as a carbon source and nitrite or nitrous oxide as intermediate products was performed using experimental data published earlier (Menyailo and Hungate, 2006; Vidal-Gavilan et al., 2013). Modified Monod kinetics was used in the dynamic biological model. The special equations were added to the common dynamic biological model to describe how isotopic fractionation between N species changes. In contrast to the generally assumed first-order kinetics, in this paper, the traditional Rayleigh equation describing stable nitrogen and oxygen isotope fractionation in nitrate was derived from the dynamic isotopic equations for any type of kinetics. In accordance with the model, in Vidal-Gavilan's experiments, the maximum specific rate of nitrate reduction was proved to be less for ethanol compared to glucose. Conversely, the maximum specific rate of nitrite reduction was proved to be much less for glucose compared to ethanol. Thus, the intermediate nitrite concentration was negligible for the ethanol experiment, while it was significant for the glucose experiment. In Menyailo's and Hungate's experiments, the low value of maximum specific rate of nitrous oxide reduction gives high intermediate value of nitrous oxide concentration. The model showed that the dynamics of nitrogen and oxygen isotope signatures are responding to the biological dynamics. Two microbial species instead of single denitrifying bacteria are proved to be more adequate to describe the total process of nitrate denitrification to dinitrogen. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Combining solid biomass combustion and stirling technology

    Energy Technology Data Exchange (ETDEWEB)

    Siemers, W.; Senkel, N. [CUTEC-Institut GmbH, Clausthal-Zellerfeld (Germany)], e-mail: werner.siemers@cutec.de

    2012-11-01

    Decentralised electricity production in combination with and based on biomass still finds some difficulties in real applications. One concept favoured in a recent project is the connection of a wood chip furmace with a Stirling engine. Because the direct exposure of the Stirling head causes numerous problems, the solution is sought in designing an indirect heat transfer system. The main challenge is the temperature level, which should be reached for high electrical efficiencies. Temperatures above 1000 deg C at the biomass combustion side are needed for an efficient heat transfer at some 850 deg C at the Stirling engine in theory. Measurements on both installations have been conducted and analyzed. After this, the design phase is started. However, no final choice on the design has been taken.

  12. Advanced radioisotope heat source for Stirling Engines

    International Nuclear Information System (INIS)

    Dobry, T.J.; Walberg, G.

    2001-01-01

    The heat exchanger on a Stirling Engine requires a thermal energy transfer from a heat source to the engine through a very limited area on the heater head circumference. Designing an effective means to assure maximum transfer efficiency is challenging. A single General Purpose Heat Source (GPHS), which has been qualified for space operations, would satisfy thermal requirements for a single Stirling Engine that would produce 55 electrical watts. However, it is not efficient to transfer its thermal energy to the engine heat exchanger from its rectangular geometry. This paper describes a conceptual design of a heat source to improve energy transfer for Stirling Engines that may be deployed to power instrumentation on space missions

  13. Cost estimating Brayton and Stirling engines

    Science.gov (United States)

    Fortgang, H. R.

    1980-01-01

    Brayton and Stirling engines were analyzed for cost and selling price for production quantities ranging from 1000 to 400,000 units per year. Parts and components were subjected to indepth scrutiny to determine optimum manufacturing processes coupled with make or buy decisions on materials and small parts. Tooling and capital equipment costs were estimated for each detail and/or assembly. For low annual production volumes, the Brayton engine appears to have a lower cost and selling price than the Stirling Engine. As annual production quantities increase, the Stirling becomes a lower cost engine than the Brayton. Both engines could benefit cost wise if changes were made in materials, design and manufacturing process as annual production quantities increase.

  14. Isotope effect on hydrated electron relaxation dynamics studied with time-resolved liquid jet photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Elkins, Madeline H.; Williams, Holly L. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Neumark, Daniel M., E-mail: dneumark@berkeley.edu [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2016-05-14

    The excited state relaxation dynamics of the solvated electron in H{sub 2}O and D{sub 2}O are investigated using time-resolved photoelectron spectroscopy in a liquid microjet. The data show that the initial excited state decays on a time scale of 75 ± 12 fs in H{sub 2}O and 102 ± 8 fs in D{sub 2}O, followed by slower relaxation on time scales of 400 ± 70 fs and 390 ± 70 fs that are isotopically invariant within the precision of our measurements. Based on the time evolution of the transient signals, the faster and slower time constants are assigned to p → s internal conversion (IC) of the hydrated electron and relaxation on the ground electronic state, respectively. This assignment is consistent with the non-adiabatic mechanism for relaxation of the hydrated electron and yields an isotope effect of 1.4 ± 0.2 for IC of the hydrated electron.

  15. Advanced Stirling Convertor (ASC) Technology Maturation

    Science.gov (United States)

    Wong, Wayne A.; Wilson, Scott; Collins, Josh; Wilson, Kyle

    2016-01-01

    The Advanced Stirling Convertor (ASC) development effort was initiated by NASA Glenn Research Center with contractor Sunpower, Inc., to develop high-efficiency thermal-to-electric power conversion technology for NASA Radioisotope Power Systems (RPSs). Early successful performance demonstrations led to the expansion of the project as well as adoption of the technology by the Department of Energy (DOE) and system integration contractor Lockheed Martin Space Systems Company as part of the Advanced Stirling Radioisotope Generator (ASRG) flight project. The ASRG integrates a pair of ASCs to convert the heat from a pair of General Purpose Heat Source (GPHS) modules into electrical power. The expanded NASA ASC effort included development of several generations of ASC prototypes or engineering units to help prepare the ASC technology and Sunpower for flight implementation. Sunpower later had two parallel contracts allowing the last of the NASA engineering units called ASC-E3 to serve as pathfinders for the ASC-F flight convertors being built for DOE. The ASC-E3 convertors utilized the ASC-F flight specifications and were built using the ASC-F design and process documentation. Shortly after the first ASC-F pair achieved initial operation, due to budget constraints, the DOE ASRG flight development contract was terminated. NASA continues to invest in the development of Stirling RPS technology including continued production of the ASC-E3 convertors, seven of which have been delivered with one additional unit in production. Starting in fiscal year 2015, Stirling Convertor Technology Maturation has been reorganized as an element of the RPS Stirling Cycle Technology Development (SCTD) Project and long-term plans for continued Stirling technology advancement are in reformulation. This paper provides a status on the ASC project, an overview of advancements made in the design and production of the ASC at Sunpower, and a summary of acceptance tests, reliability tests, and tactical

  16. Experimental and Computational Analysis of Unidirectional Flow Through Stirling Engine Heater Head

    Science.gov (United States)

    Wilson, Scott D.; Dyson, Rodger W.; Tew, Roy C.; Demko, Rikako

    2006-01-01

    A high efficiency Stirling Radioisotope Generator (SRG) is being developed for possible use in long-duration space science missions. NASA s advanced technology goals for next generation Stirling convertors include increasing the Carnot efficiency and percent of Carnot efficiency. To help achieve these goals, a multi-dimensional Computational Fluid Dynamics (CFD) code is being developed to numerically model unsteady fluid flow and heat transfer phenomena of the oscillating working gas inside Stirling convertors. In the absence of transient pressure drop data for the zero mean oscillating multi-dimensional flows present in the Technology Demonstration Convertors on test at NASA Glenn Research Center, unidirectional flow pressure drop test data is used to compare against 2D and 3D computational solutions. This study focuses on tracking pressure drop and mass flow rate data for unidirectional flow though a Stirling heater head using a commercial CFD code (CFD-ACE). The commercial CFD code uses a porous-media model which is dependent on permeability and the inertial coefficient present in the linear and nonlinear terms of the Darcy-Forchheimer equation. Permeability and inertial coefficient were calculated from unidirectional flow test data. CFD simulations of the unidirectional flow test were validated using the porous-media model input parameters which increased simulation accuracy by 14 percent on average.

  17. Free piston space Stirling technology program

    Science.gov (United States)

    Dochat, G. R.; Dhar, M.

    1989-01-01

    MTI recently completed an initial technology feasibility program for NASA by designing, fabricating and testing a space power demonstrator engine (SPDE). This program, which confirms the potential of free-piston Stirling engines, provided the major impetus to initiate a free-piston Stirling space engine (SSE) technology program. The accomplishments of the SPDE program are reviewed, and an overview of the SSE technology program and technical status to date is provided. It is shown that progress in both programs continues to justify its potential for either nuclear or solar space power missions.

  18. Dynamic response of the high flux isotope reactor structure caused by nearby heavy load drop

    International Nuclear Information System (INIS)

    Chang, Shih-Jung.

    1995-01-01

    A heavy load of 50,000 lb is assumed to drop from 10 ft above the bottom of the High Flux Isotope Reactor (HFIR) pool at the loading station. The consequences of the dynamic impact to the bottom slab of the pool and to the nearby HFIR reactor vessel are analyzed by applying the ABAQUS computer code The results show that both the BM vessel structure and its supporting legs are subjected to elastic disturbances only and, therefore, will not be damaged. The bottom slab of the pool, however, will be damaged to about half of the slab thickness. The velocity response spectrum at the concrete floor next to the HFIR vessel as a result of the vibration caused by the impact is obtained. It is concluded, that the damage caused by heavy load drop at the loading station is controlled by the slab damage and the nearby HFIR vessel and the supporting legs will not be damaged

  19. Nitrogen dynamics in subtropical fringe and basin mangrove forests inferred from stable isotopes.

    Science.gov (United States)

    Reis, Carla Roberta Gonçalves; Nardoto, Gabriela Bielefeld; Rochelle, André Luis Casarin; Vieira, Simone Aparecida; Oliveira, Rafael Silva

    2017-03-01

    Mangroves exhibit low species richness compared to other tropical forests, but great structural and functional diversity. Aiming to contribute to a better understanding of the functioning of mangrove forests, we investigated nitrogen (N) dynamics in two physiographic types of mangroves (fringe and basin forests) in southeastern Brazil. Because fringe forests are under great influence of tidal flushing we hypothesized that these forests would exhibit higher N cycling rates in sediment and higher N losses to the atmosphere compared to basin forests. We quantified net N mineralization and nitrification rates in sediment and natural abundance of N stable isotopes (δ 15 N) in the sediment-plant-litter system. The fringe forest exhibited higher net N mineralization rates and δ 15 N in the sediment-plant-litter system, but net nitrification rates were similar to those of the basin forest. The results of the present study suggest that fringe forests exhibit higher N availability and N cycling in sediment compared to basin forests.

  20. Advanced Stirling Radioisotope Generator (ASRG) Thermal Power Model in MATLAB

    Science.gov (United States)

    Wang, Xiao-Yen, J.

    2012-01-01

    This paper presents a one-dimensional steady-state mathematical thermal power model of the ASRG. It aims to provide a guideline of understanding how the ASRG works and what can change its performance. The thermal dynamics and energy balance of the generator is explained using the thermal circuit of the ASRG. The Stirling convertor performance map is used to represent the convertor. How the convertor performance map is coupled in the thermal circuit is explained. The ASRG performance characteristics under i) different sink temperatures and ii) over the years of mission (YOM) are predicted using the one-dimensional model. Two Stirling converter control strategies, i) fixing the hot-end of temperature of the convertor by adjusting piston amplitude and ii) fixing the piston amplitude, were tested in the model. Numerical results show that the first control strategy can result in a higher system efficiency than the second control strategy when the ambient gets warmer or the general-purpose heat source (GPHS) fuel load decays over the YOM. The ASRG performance data presented in this paper doesn't pertain to the ASRG flight unit. Some data of the ASRG engineering unit (EU) and flight unit that are available in public domain are used in this paper for the purpose of numerical studies.

  1. Nitrogen isotopes suggest a change in nitrogen dynamics between the Late Pleistocene and modern time in Yukon, Canada

    Science.gov (United States)

    Longstaffe, Fred J.; Zazula, Grant

    2018-01-01

    A magnificent repository of Late Pleistocene terrestrial megafauna fossils is contained in ice-rich loess deposits of Alaska and Yukon, collectively eastern Beringia. The stable carbon (δ13C) and nitrogen (δ15N) isotope compositions of bone collagen from these fossils are routinely used to determine paleodiet and reconstruct the paleoecosystem. This approach requires consideration of changes in C- and N-isotope dynamics over time and their effects on the terrestrial vegetation isotopic baseline. To test for such changes between the Late Pleistocene and modern time, we compared δ13C and δ15N for vegetation and bone collagen and structural carbonate of some modern, Yukon, arctic ground squirrels with vegetation and bones from Late Pleistocene fossil arctic ground squirrel nests preserved in Yukon loess deposits. The isotopic discrimination between arctic ground squirrel bone collagen and their diet was measured using modern samples, as were isotopic changes during plant decomposition; Over-wintering decomposition of typical vegetation following senescence resulted in a minor change (~0–1 ‰) in δ13C of modern Yukon grasses. A major change (~2–10 ‰) in δ15N was measured for decomposing Yukon grasses thinly covered by loess. As expected, the collagen-diet C-isotope discrimination measured for modern samples confirms that modern vegetation δ13C is a suitable proxy for the Late Pleistocene vegetation in Yukon Territory, after correction for the Suess effect. The N-isotope composition of vegetation from the fossil arctic ground squirrel nests, however, is determined to be ~2.8 ‰ higher than modern grasslands in the region, after correction for decomposition effects. This result suggests a change in N dynamics in this region between the Late Pleistocene and modern time. PMID:29447202

  2. Double acting stirling engine piston ring

    Science.gov (United States)

    Howarth, Roy B.

    1986-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  3. Two piston V-type Stirling engine

    Science.gov (United States)

    Corey, John A.

    1987-01-01

    A two piston Stirling engine which includes a heat exchanger arrangement placing the cooler and regenerator directly adjacent the compression space for minimal cold duct volume; a sealing arrangement which eliminates the need for piston seals, crossheads and piston rods; and a simplified power control system.

  4. Experimental research on the Stirling engine

    Science.gov (United States)

    Ishizaki, Y.; Tani, Y.; Haramura, N.

    1982-01-01

    Experiments on Stirling engines of the 50 KW class were conducted to clarify the characteristics of the engine and its problems. The problems involve durability of the high temperature heat exchanger which is exposed to high flame temperatures above 1600 C, thermal distortion and high temperature corrosion of the devices near combustion, and of the preheater.

  5. Piston rod seal for a Stirling engine

    Science.gov (United States)

    Shapiro, Wilbur

    1984-01-01

    In a piston rod seal for a Stirling engine, a hydrostatic bearing and differential pressure regulating valve are utilized to provide for a low pressure differential across a rubbing seal between the hydrogen and oil so as to reduce wear on the seal.

  6. Quirks of Stirling's Approximation

    Science.gov (United States)

    Macrae, Roderick M.; Allgeier, Benjamin M.

    2013-01-01

    Stirling's approximation to ln "n"! is typically introduced to physical chemistry students as a step in the derivation of the statistical expression for the entropy. However, naive application of this approximation leads to incorrect conclusions. In this article, the problem is first illustrated using a familiar "toy…

  7. The Stirling Lesson-Sampling Instruments.

    Science.gov (United States)

    White, D. R.

    A long-term Leverhulme Research Project was established at Stirling University in 1970 to investigate the potential of microteaching as a major ingredient in the preparation of graduate high school teachers in Scotland. Members of the research team developed systematic observation schedules for each of the skills, in order to sharpen the focus of…

  8. A transient one-dimensional numerical model for kinetic Stirling engine

    International Nuclear Information System (INIS)

    Wang, Kai; Dubey, Swapnil; Choo, Fook Hoong; Duan, Fei

    2016-01-01

    Highlights: • A non-equilibrium thermal mode with considering loses is adopted in Stirling engine. • Good agreements are achieved for predicting various critical system parameters. • Differences between helium and hydrogen systems are highlighted and analyzed. • Pressure drop of helium system is much larger and more sensitive to frequency. - Abstract: A third-order numerical model based on one-dimensional computational fluid dynamics is developed for kinetic Stirling engines. Various loss mechanisms in Stirling engines, including gas spring hysteresis loss, shuttle loss, appendix displacer gap loss, gas leakage loss, finite speed loss, piston friction loss, pressure drop loss, heat conduction loss, mechanical loss and imperfect heat transfer, are considered and embedded into the basic control equations. The non-equilibrium thermal model is adopted for the regenerator to capture the oscillating features of the gas and solid temperatures. To improve the numerical stability and accuracy, the implicit second-order time difference scheme and the second-order upwind scheme are adopted for discretizing the time differential terms and convective terms, respectively. Experimental validations are then conducted on a beta-type Stirling engine with the extensive experimental data for diverse working conditions. The results show that the developed model has better accuracies than the previous second-order models. Good agreements are achieved for predicting various critical system parameters, including pressure-volume diagram, indicated power, brake power, indicated efficiency, brake efficiency and mechanical efficiency. In particular, both the experiments and simulations show that the Stirling engine charged with helium tends to have much lower optimal working frequencies and poorer performances compared to the hydrogen system. Based on the analyses of the losses, it reveals that the pressure drop in the flow channels plays a critical role in shaping the different

  9. Nitrogen Dynamic Study on Rice Mutant Lines Using 15N Isotope Techniques

    International Nuclear Information System (INIS)

    Ahmad Nazrul Abd Wahid; Shyful Azizi Abdul Rahman; Abdul Rahim Harun

    2015-01-01

    Malaysian Nuclear Agency in collaboration with UPM and MARDI has produced two types of rice mutant lines of MR219, viz. MR219-4 and MR219-9 developed under rice radiation mutagenenesis programme for adaptability to aerobic conditions. Aerobic cultivating is rice cultivation system on well drained soil and using minimal water input. At Malaysian Nuclear Agency, a nitrogen fertilization study in aerobic condition for the rice mutant lines was carried out in the shade house and field. The study is intended to examine and assess the dynamics of nitrogen by rice mutant lines through the different soil water management and nitrogen levels. Direct 15 N isotopic tracer method was used in this study, whereby the 15 N labeled urea fertilizer was utilized as a tracer for nitrogen nutrient uptake by the test crops. This paper is intended to highlight the progress that has been made in the study of the nitrogen dynamics on MR219-4 and MR219-9 rice mutant lines. (author)

  10. Phosphorus dynamics of representative volcanic ash soils through the use of conventional and isotopic techniques

    International Nuclear Information System (INIS)

    Pino, I.; Parada, A.M.; Luzio, W.

    2002-01-01

    In Chile, the total extension covered by volcanic ash soils including recent and old volcanic deposits is around 5,244,400 ha. This study was carried out in 'La Araucania and Los Lagos' regions (IX and X Regions of Chile respectively), which cover approximately 2,350,000 ha. The main chemical characteristics of these soils are: very low available P (Olsen); a high P retention capacity and a high quantity of aluminum (Al) associated to a high amount of short-range order minerals. The main objective of this study was the characterization of the P dynamics of representative volcanic soils through the use of conventional and isotopic techniques. In the X Region (Los Lagos) of Chile samples from the arable layer (0-20 cm) of eleven soils (Ultisols and Andisols) were collected. Four entire soil profiles were sampled in the IX Region (Araucania). The characterization of soils was made utuilising conventional and isotopic analyses. The P retention was over 85% in all soils, except for the Metrenco soil series (Paleudult). Nevertheless, the P retention of this soil, from 72% to 79% can be also considered high for a non-volcanic ash soil. In the same way, the Al+1/2 Fe (ox) in all profiles showed high values for non-volcanic ash soils. These results indicate the great difficulty in increasing the available P in these soils, even when high rates of phosphate fertilizers are applied. The principal P-limiting factor in both regions was the P intensity factor. (author)

  11. Radioactive and stable cesium isotope distributions and dynamics in Japanese cedar forests.

    Science.gov (United States)

    Yoschenko, Vasyl; Takase, Tsugiko; Hinton, Thomas G; Nanba, Kenji; Onda, Yuichi; Konoplev, Alexei; Goto, Azusa; Yokoyama, Aya; Keitoku, Koji

    2018-06-01

    Dynamics of the Fukushima-derived radiocesium and distribution of the natural stable isotope 133 Cs in Japanese cedar (Cryptomeria japonica D. Don) forest ecosystems were studied during 2014-2016. For the experimental site in Yamakiya, Fukushima Prefecture, we present the redistribution of radiocesium among ecosystem compartments during the entire observation period, while the results obtained at another two experimental site were used to demonstrate similarity of the main trends in the Japanese forest ecosystems. Our observations at the Yamakiya site revealed significant redistribution of radiocesium between the ecosystem compartments during 2014-2016. During this same period radionuclide inventories in the aboveground tree biomass were relatively stable, however, radiocesium in forest litter decreased from 20 ± 11% of the total deposition in 2014 to 4.6 ± 2.7% in 2016. Radiocesium in the soil profile accumulated in the 5-cm topsoil layers. In 2016, more than 80% of the total radionuclide deposition in the ecosystem resided in the 5-cm topsoil layer. The radiocesium distribution between the aboveground biomass compartments at Yamakiya during 2014-2016 was gradually approaching a quasi-equilibrium distribution with stable cesium. Strong correlations of radioactive and stable cesium isotope concentrations in all compartments of the ecosystem have not been reached yet. However, in some compartments the correlation is already strong. An increase of radiocesium concentrations in young foliage in 2016, compared to 2015, and an increase in 2015-2016 of the 137 Cs/ 133 Cs concentration ratio in the biomass compartments with strong correlations indicate an increase in root uptake of radiocesium from the soil profile. Mass balance of the radionuclide inventories, and accounting for radiocesium fluxes in litterfall, throughfall and stemflow, enabled a rough estimate of the annual radiocesium root uptake flux as 2 ± 1% of the total inventory in the ecosystem

  12. CFD analysis of a diaphragm free-piston Stirling cryocooler

    Science.gov (United States)

    Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

    2016-10-01

    This paper presents a Computational Fluid Dynamics (CFD) analysis of a novel free-piston Stirling cryocooler that uses a pair of metal diaphragms to seal and suspend the displacer. The diaphragms allow the displacer to move without rubbing or moving seals. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicated the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. The diaphragm's large diameter and short stroke produces a significant radial component to the oscillating flow fields inside the cryocooler which were not modelled in the one-dimensional analysis tool Sage that was used to design the prototypes. Compared with standard pistons, the diaphragm geometry increases the gas-to-wall heat transfer due to the higher velocities and smaller hydraulic diameters. A Computational Fluid Dynamics (CFD) model of the cryocooler was constructed to understand the underlying fluid-dynamics and heat transfer mechanisms with the aim of further improving performance. The CFD modelling of the heat transfer in the radial flow fields created by the diaphragms shows the possibility of utilizing the flat geometry for heat transfer, reducing the need for, and the size of, expensive heat exchangers. This paper presents details of a CFD analysis used to model the flow and gas-to-wall heat transfer inside the second prototype cryocooler, including experimental validation of the CFD to produce a robust analysis.

  13. Structural design of Stirling engine with free pistons

    Science.gov (United States)

    Matusov, Jozef; Gavlas, Stanislav; Malcho, Milan

    2014-08-01

    Stirling engine is a device that converts thermal energy to mechanical work, which is mostly used to drive a generator of electricity. Advantage of Stirling engine is that it works with closed-cycle, where working medium is regularly cooled and heated, which acts on the working piston. This engine can be made in three modifications - alpha, beta, gamma. This paper discusses the design of the gamma Stirling engine with free pistons.

  14. THE STIRLING GAS REFRIGERATING MACHINE MECHANICAL DESIGN IMPROVING

    Directory of Open Access Journals (Sweden)

    V. V. Trandafilov

    2016-06-01

    Full Text Available To improve the mechanical design of the piston Stirling gas refrigeration machine the structural optimization of rotary vane Stirling gas refrigeration machine is carried out. This paper presents the results of theoretical research. Analysis and prospects of rotary vane Stirling gas refrigeration machine for domestic and industrial refrigeration purpose are represented. The results of a patent search by mechanisms of transformation of rotary vane machines are discussed.

  15. THE STIRLING GAS REFRIGERATING MACHINE MECHANICAL DESIGN IMPROVING

    Directory of Open Access Journals (Sweden)

    V. V. Trandafilov

    2016-02-01

    Full Text Available To improve the mechanical design of the piston Stirling gas refrigeration machine the structural optimization of rotary vane Stirling gas refrigeration machine is carried out. This paper presents the results of theoretical research. Analysis and prospects of rotary vane Stirling gas refrigeration machine for domestic and industrial refrigeration purpose are represented. The results of a patent search by mechanisms of transformation of rotary vane machines are discussed

  16. Conceptualisation of Snowpack Isotope Dynamics in Spatially Distributed Tracer-Aided Runoff Models in Snow Influenced Northern Cathments

    Science.gov (United States)

    Ala-aho, P. O. A.; Tetzlaff, D.; Laudon, H.; McNamara, J. P.; Soulsby, C.

    2016-12-01

    We use the Spatially distributed Tracer-Aided Rainfall-Runoff (STARR) modelling framework to explore non-stationary flow and isotope response in three northern headwater catchments. The model simulates dynamic, spatially variable tracer concentration in different water stores and fluxes within a catchment, which can constrain internal catchment mixing processes, flow paths and associated water ages. To date, a major limitation in using such models in snow-dominated catchments has been the difficulties in paramaterising the isotopic transformations in snowpack accumulation and melt. We use high quality long term datasets for hydrometrics and stable water isotopes collected in three northern study catchments for model calibration and testing. The three catchments exhibit different hydroclimatic conditions, soil and vegetation types, and topographic relief, which brings about variable degree of snow dominance across the catchments. To account for the snow influence we develop novel formulations to estimate the isotope evolution in the snowpack and melt. Algorithms for the isotopic evolution parameterize an isotopic offset between snow evaporation and melt fluxes and the remaining snow storage. The model for each catchment is calibrated to match both streamflow and tracer concentration at the stream outlet to ensure internal consistency of the system behaviour. The model is able to reproduce the streamflow along with the spatio-temporal differences in tracer concentrations across the three studies catchments reasonably well. Incorporating the spatially distributed snowmelt processes and associated isotope transformations proved essential in capturing the stream tracer reponse for strongly snow-influenced cathments. This provides a transferrable tool which can be used to understand spatio-temporal variability of mixing and water ages for different storages and flow paths in other snow influenced, environments.

  17. On structural identifiability analysis of the cascaded linear dynamic systems in isotopically non-stationary 13C labelling experiments.

    Science.gov (United States)

    Lin, Weilu; Wang, Zejian; Huang, Mingzhi; Zhuang, Yingping; Zhang, Siliang

    2018-06-01

    The isotopically non-stationary 13C labelling experiments, as an emerging experimental technique, can estimate the intracellular fluxes of the cell culture under an isotopic transient period. However, to the best of our knowledge, the issue of the structural identifiability analysis of non-stationary isotope experiments is not well addressed in the literature. In this work, the local structural identifiability analysis for non-stationary cumomer balance equations is conducted based on the Taylor series approach. The numerical rank of the Jacobian matrices of the finite extended time derivatives of the measured fractions with respect to the free parameters is taken as the criterion. It turns out that only one single time point is necessary to achieve the structural identifiability analysis of the cascaded linear dynamic system of non-stationary isotope experiments. The equivalence between the local structural identifiability of the cascaded linear dynamic systems and the local optimum condition of the nonlinear least squares problem is elucidated in the work. Optimal measurements sets can then be determined for the metabolic network. Two simulated metabolic networks are adopted to demonstrate the utility of the proposed method. Copyright © 2018 Elsevier Inc. All rights reserved.

  18. A dynamic isotope power system for Space Exploration Initiative surface transport systems

    International Nuclear Information System (INIS)

    Hunt, M.E.; Harty, R.B.; Cataldo, R.

    1992-03-01

    The Dynamic Isotope Power System (DIPS) Demonstration Program, sponsored by the U.S. Department of Energy with support funding from NASA, is currently focused on the development of a standardized 2.5-kWe portable generator for multiple applications on the lunar or Martian surface. A variety of remote and mobile potential applications have been identified by NASA, including surface rovers for both short- and extended-duration missions, remote power to science packages, and backup to central base power. Recent work focused on refining the 2.5-kWe design and emphasizing the compatibility of the system with potential surface transport systems. Work included an evaluation of the design to ensure compatibility with the Martian atmosphere while imposing only a minor mass penalty on lunar operations. Additional work included a study performed to compare the DIPS with regenerative fuel cell systems for lunar mobile and remote power systems. Power requirements were reviewed and a modular system chosen for the comparison. 4 refs

  19. A dynamic isotope power system portable generator for the Moon or Mars

    International Nuclear Information System (INIS)

    Johnson, R.A.; Hunt, M.E.; Mason, L.S.

    1991-01-01

    The Dynamic Isotope Power Systems (DIPS) Demonstration Program is focused on a standardized 2.5 kWe portable generator for multipole uses on the Lunar or Martian surface. A variety of potential remote or mobile applications has been identified by the National Aeronautics and Space Administration (NASA). These applications include remote power to science packages, surface rovers for both short and extended duration missions, and back up to central base power. In this paper, reviews conducted on alternative power sources for these applications are described. These include the comparison of DIPS to regenerative fuel cells (RFCs) related to such things as mass, complexity, and life cycle costs, and concluded that each power source has application. Recent work is presented refining the 2.5 kWe design to assure compatibility with the Martian environment while imposing only a minor mass penalty on Lunar operations. This was accomplished by limiting temperatures, except in the heat source unit (HSU), to the nonrefractory materials regime and protecting the necessary refractories in the HSU from the environment. Design changes to the HSU are described. Finally, work related to recent concerns regarding astronaut radiation doses is described. This work includes the bases for the calculations to determine the necessary shielding or operational limitations

  20. Diagnostic value of electrocardiography, dynamic isotope studies and angiography in coronary heart disease

    International Nuclear Information System (INIS)

    Haas, J.

    1986-01-01

    The goal of this work is on the basis of the case histories of 36 patients with heart anamneses (27 with electrocardiographically and/or enzymatically detected heart infarcts, 9 with various cardial diseases) to test the diagnostic value of stress electrocardiograms, dynamic isotope examinations of the heart and coronary angiographies in the cases of myocardial infarcts, heart wall aneurysms, coronary heart disease and in the determination of the global discharge fraction, specifically broad scanning (heart front, side and back walls) as well as fine scanning (individual coronary vessel branches). In the case of myocardial infarct the stress EKG and the heart scintigraphy agree with one another to a large degree, whereby scintigraphy (with 99mTc-DPTA) in addition detects infarcted myocardial regions. In the diagnosis of heart wall aneurysms scintigraphy and ventriculography had the same results in 91.6% of the cases. Coronary heart disease results agreed for all three methods in 91.7% of the cases and with scintigraphy and angiography in 94.4%. The degree of agreement between scintigraphy and coronary angiography is confirmed in the literature. One-, two- and 3-vessel diseases can be determined with these two methods in 90 to 75% agreement. The result lies thereby above the values of 201Tl-myocardial scintigraphy given in the literature. Also the global discharge fraction shows scintigraphic as well as angiographic agreement of almost 90%. (TRV) [de

  1. Dynamics of lake Koeycegiz, SW Turkey: An environmental isotopic and hydrochemical study

    International Nuclear Information System (INIS)

    Bayari, C.S.; Kurttas, T.; Tezcan, L.

    2001-01-01

    Lake Koeycegiz, located in southwestern Turkey, is a meromictic lake with a surface area of 55 km 2 . Impermeable ophiolitic rocks, and groundwater bearing alluvium and karstified limestone are the major geologic units around the lake. Lake Koeycegiz, fed mainly by rainfall and stream flow, discharges into the Mediterranean Sea via a 14 km long natural channel. The average water level is estimated to be slightly above the sea level and the estimated lake volume is 826 million m 3 . Lake level fluctuations are well correlated with rainfall intensity. Lake Koeycegiz comprises two major basins: Sultaniye basin (-32m) at the south and Koeycegiz Basin (-24m) at the north which are connected by a 12m deep strait. Environmental isotopic and chemical data reveals that the Lake Koeycegiz has complicated mixing dynamics which are controlled mainly by density-driven flow of waters from different origins. The lake is fed mainly by rainfall and stream flow as low density waters and by high density thermal groundwater inflow at the southern coast. Complete annual mixing cannot be achieved, because of the density difference between mixolimnion and recharge. Continuous high-density thermal water input into the Sultaniye basin is the major factor controlling the lake dynamics. The high density thermal groundwater discharging into the lake sinks to the bottom of Sultaniye basin and overflows toward the north along the bottom surface. During its travel, dense bottom water is mixed with mixolimnion water and as the distance from the thermal water inflow increases, the density tends to decrease throughout the lake. Calculations based on long-term average electrical conductivity data reveal that about 60% of mixolimnion in both basins is replenished annually, whereas the annual mixing with mixolinmion for Sultaniye and Koeycegiz Basins is 20% and 30%, respectively. Turnover times for mixolimnion and monimolimnions of Sultaniye and Koeycegiz Basins are estimated to be 2 years, 5 years

  2. Summary of Stirling Convertor Testing at NASA Glenn Research Center in Support of Stirling Radioisotope Power System Development

    Science.gov (United States)

    Schifer, Nicholas A.; Oriti, Salvatore M.

    2013-01-01

    The NASA Glenn Research Center (GRC) has been testing 100 We class, free-piston Stirling convertors for potential use in Stirling Radioisotope Power Systems (RPS) for space science and exploration missions. Free-piston Stirling convertors are capable of achieving a 38% conversion efficiency, making Stirling attractive for meeting future power system needs in light of the shrinking U.S. plutonium fuel supply. Convertors currently on test include four Stirling Technology Demonstration Convertors (TDCs), manufactured by the Stirling Technology Company (STC), and six Advanced Stirling Convertors (ASCs), manufactured by Sunpower, Inc. Total hours of operation is greater than 514,000 hours (59 years). Several tests have been initiated to demonstrate the functionality of Stirling convertors for space applications, including: in-air extended operation, thermal vacuum extended operation. Other tests have also been conducted to characterize Stirling performance in anticipated mission scenarios. Data collected during testing has been used to support life and reliability estimates, drive design changes and improve quality, and plan for expected mission scenarios. This paper will provide a summary of convertors tested at NASA GRC and discuss lessons learned through extended testing.

  3. Optimization and application of ICPMS with dynamic reaction cell for precise determination of 44Ca/40Ca isotope ratios.

    Science.gov (United States)

    Boulyga, Sergei F; Klötzli, Urs; Stingeder, Gerhard; Prohaska, Thomas

    2007-10-15

    An inductively coupled plasma mass spectrometer with dynamic reaction cell (ICP-DRC-MS) was optimized for determining (44)Ca/(40)Ca isotope ratios in aqueous solutions with respect to (i) repeatability, (ii) robustness, and (iii) stability. Ammonia as reaction gas allowed both the removal of (40)Ar+ interference on (40)Ca+ and collisional damping of ion density fluctuations of an ion beam extracted from an ICP. The effect of laboratory conditions as well as ICP-DRC-MS parameters such a nebulizer gas flow rate, rf power, lens potential, dwell time, or DRC parameters on precision and mass bias was studied. Precision (calculated using the "unbiased" or "n - 1" method) of a single isotope ratio measurement of a 60 ng g(-1) calcium solution (analysis time of 6 min) is routinely achievable in the range of 0.03-0.05%, which corresponded to the standard error of the mean value (n = 6) of 0.012-0.020%. These experimentally observed RSDs were close to theoretical precision values given by counting statistics. Accuracy of measured isotope ratios was assessed by comparative measurements of the same samples by ICP-DRC-MS and thermal ionization mass spectrometry (TIMS) by using isotope dilution with a (43)Ca-(48)Ca double spike. The analysis time in both cases was 1 h per analysis (10 blocks, each 6 min). The delta(44)Ca values measured by TIMS and ICP-DRC-MS with double-spike calibration in two samples (Ca ICP standard solution and digested NIST 1486 bone meal) coincided within the obtained precision. Although the applied isotope dilution with (43)Ca-(48)Ca double-spike compensates for time-dependent deviations of mass bias and allows achieving accurate results, this approach makes it necessary to measure an additional isotope pair, reducing the overall analysis time per isotope or increasing the total analysis time. Further development of external calibration by using a bracketing method would allow a wider use of ICP-DRC-MS for routine calcium isotopic measurements, but it

  4. Stirling Energy Module (SEM) as Micro-CHP; Stirling Energy Module (SEM) als Mini-BHKW

    Energy Technology Data Exchange (ETDEWEB)

    Schlegel, A.

    2006-07-01

    Since many years, a lot of effort is being put into the development of combined heat and power units (CHP) for the decentralised production of electric power. For long time, the main focus was on fuel cells. In the meantime, the Stirling technology, which is based upon classical mechanical engineering and innovative technical concepts, proceeded in its development as well. The following article describes the technology and the actual state of the development of the Stirling Energy Module (SEM) for the application as Micro-CHP in one-family-houses. SEM is based on a free-piston engine with a linear power generator, producing electric power while heating. The Stirling engine is planned the be introduced into the market as a replacement for the conventional heating systems within a couple of years. (author)

  5. Composite Matrix Regenerator for Stirling Engines

    Science.gov (United States)

    Knowles, Timothy R.

    1997-01-01

    This project concerns the design, fabrication and testing of carbon regenerators for use in Stirling power convertors. Radial fiber design with nonmetallic components offers a number of potential advantages over conventional steel regenerators: reduced conduction and pressure drop losses, and the capability for higher temperature, higher frequency operation. Diverse composite fabrication methods are explored and lessons learned are summarized. A pulsed single-blow test rig has been developed that has been used for generating thermal effectiveness data for different flow velocities. Carbon regenerators have been fabricated by carbon vapor infiltration of electroflocked preforms. Performance data in a small Stirling engine are obtained. Prototype regenerators designed for the BP-1000 power convertor were fabricated and delivered to NASA-Lewis.

  6. Coefficient of performance of Stirling refrigerators

    Science.gov (United States)

    E Mungan, Carl

    2017-09-01

    Stirling coolers transfer heat in or out of the working fluid during all four stages of their operation, and their coefficient of performance depends on whether the non-isothermal heat exchanges are performed reversibly or irreversibly. Both of these possibilities can in principle be arranged. Notably, if the working fluid is an ideal gas, the input of energy in the form of heat during one isochoric step is equal in magnitude to the output during the other isochoric step in the cycle. The theoretical performance of the fridge can then attain the reversible Carnot limit if a regenerator is used, which is a high heat capacity material through which the gas flows. Various Stirling refrigerator configurations are analysed in this article at a level of presentation suitable for an introductory undergraduate thermodynamics course.

  7. NASA Lewis Stirling SPRE testing and analysis with reduced number of cooler tubes

    International Nuclear Information System (INIS)

    Wong, W.A.; Cairelli, J.E.; Swec, D.M.; Doeberling, T.J.; Lakatos, T.F.; Madi, F.J.

    1994-01-01

    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

  8. A thermodynamic study for the optimization of stable operation of free piston Stirling engines

    Energy Technology Data Exchange (ETDEWEB)

    Rogdakis, E.D.; Bormpilas, N.A.; Koniakos, I.K. [National Technical Univerisity, Athens (Greece). Dept. of Mechanical Engineering

    2004-03-01

    One of the most novel applications of the Stirling cycle is in the free piston configuration that was initially designed by W. Beale. In free piston Stirling engines (FPSEs), there are no mechanical linkages coupling the pistons or displacers, the motions of the reciprocating components follow the working gas pressure variations. Fillipo de Monte and G. Benvenuto have recently proposed a linearization technique of the dynamic balance equations. The aim of this paper is to predict the thermodynamic conditions for stable operation of FPSEs and their modeling. The equations of the angular velocity are solved analytically in terms of the working gas mass and the displacer-piston phase angle of the machine. Using the criterion of stable engine cyclic steady operation, a mathematically rigorous form is obtained for the main parameters of the engine. Furthermore, for simplicity reasons, thermodynamic magnitudes are obtained using the Schmidt analysis (isothermal model). (author)

  9. A thermodynamic study for the optimization of stable operation of free piston Stirling engines

    International Nuclear Information System (INIS)

    Rogdakis, E.D.; Bormpilas, N.A.; Koniakos, I.K.

    2004-01-01

    One of the most novel applications of the Stirling cycle is in the free piston configuration that was initially designed by W. Beale. In free piston Stirling engines (FPSEs), there are no mechanical linkages coupling the pistons or displacers, the motions of the reciprocating components follow the working gas pressure variations. Fillipo de Monte and G. Benvenuto have recently proposed a linearization technique of the dynamic balance equations. The aim of this paper is to predict the thermodynamic conditions for stable operation of FPSEs and their modeling. The equations of the angular velocity are solved analytically in terms of the working gas mass and the displacer-piston phase angle of the machine. Using the criterion of stable engine cyclic steady operation, a mathematically rigorous form is obtained for the main parameters of the engine. Furthermore, for simplicity reasons, thermodynamic magnitudes are obtained using the Schmidt analysis (isothermal model)

  10. Free-piston Stirling Engine system considerations for various space power applications

    Science.gov (United States)

    Dochat, George R.; Dhar, Manmohan

    1991-01-01

    Free-Piston Stirling Engines (FPSE) have the potential to provide high reliability, long life, and efficient operation. Therefore, they are excellent candidates for the dynamic power conversion module of a space-based, power-generating system. FPSE can be coupled with many potential heat sources (radioisotope, solar, or nuclear reactor), various heat input systems (pumped loop, heat pipe), heat rejection (pumped loop or heat pipe), and various power management and distribution systems (ac, dc, high or low voltage, and fixed or variable load). This paper reviews potential space missions that can be met using free-piston Stirling engines and discusses options of various system integration approaches. This paper briefly outlines the program and recent progress.

  11. Influence of minor geometric features on Stirling pulse tube cryocooler performance

    Science.gov (United States)

    Fang, T.; Spoor, P. S.; Ghiaasiaan, S. M.; Perrella, M.

    2017-12-01

    Minor geometric features and imperfections are commonly introduced into the basic design of multi-component systems to simplify or reduce the manufacturing expense. In this work, the cooling performance of a Stirling type cryocooler was tested in different driving powers, cold-end temperatures and inclination angles. A series of Computational Fluid Dynamics (CFD) simulations based on a prototypical cold tip was carried out. Detailed CFD model predictions were compared with the experiment and were used to investigate the impact of such apparently minor geometric imperfections on the performance of Stirling type pulse tube cryocoolers. Predictions of cooling performance and gravity orientation sensitivity were compared with experimental results obtained with the cryocooler prototypes. The results indicate that minor geometry features in the cold tip assembly can have considerable negative effects on the gravity orientation sensitivity of a pulse tube cryocooler.

  12. Organic matter dynamics and stable isotope signature as tracers of the sources of suspended sediment

    Directory of Open Access Journals (Sweden)

    Y. Schindler Wildhaber

    2012-06-01

    Full Text Available Suspended sediment (SS and organic matter in rivers can harm brown trout Salmo trutta by affecting the health and fitness of free swimming fish and by causing siltation of the riverbed. The temporal and spatial dynamics of sediment, carbon (C, and nitrogen (N during the brown trout spawning season in a small river of the Swiss Plateau were assessed and C isotopes as well as the C/N atomic ratio were used to distinguish autochthonous and allochthonous sources of organic matter in SS loads. The visual basic program IsoSource with 13Ctot and 15N as input isotopes was used to quantify the temporal and spatial sources of SS. Organic matter concentrations in the infiltrated and suspended sediment were highest during low flow periods with small sediment loads and lowest during high flow periods with high sediment loads. Peak values in nitrate and dissolved organic C were measured during high flow and high rainfall, probably due to leaching from pasture and arable land. The organic matter was of allochthonous sources as indicated by the C/N atomic ratio and δ13Corg. Organic matter in SS increased from up- to downstream due to an increase of pasture and arable land downstream of the river. The mean fraction of SS originating from upper watershed riverbed sediment decreased from up to downstream and increased during high flow at all measuring sites along the course of the river. During base flow conditions, the major sources of SS are pasture, forest and arable land. The latter increased during rainy and warmer winter periods, most likely because both triggered snow melt and thus erosion. The measured increase in DOC and nitrate concentrations during high flow support these modeling results. Enhanced soil erosion processes on pasture and arable land are expected with increasing heavy rain events and less snow during winter seasons due to climate change. Consequently, SS and organic

  13. Free-piston Stirling engine system considerations for various space power applications

    International Nuclear Information System (INIS)

    Dochat, G.R.; Dhar, M.

    1991-01-01

    The U.S. Government is evaluating power requirements for future space applications. As power requirements increase solar or nuclear dynamic systems become increasingly attractive. Free-Piston Stirling Engines (FPSE) have the potential to provide high reliability, long life, and efficient operation. Therefore, they are excellent candidates for the dynamic power conversion module of a space-based, power-generating system. FPSE can be coupled with many potential heat sources (radioisotope, solar, or nuclear reactor), various heat input systems (pumped loop, heat pipe), heat rejection (pumped loop or heat pipe), and various power management and distribution systems (AC, DC, high or low voltage, and fixed or variable load). This paper will review potential space missions that can be met using free-piston Stirling engines and discusses options of various system integration approaches. Currently free-piston Stirling engine technology for space power applications is being developed under contract with NASA-Lewis Research Center. This paper will also briefly outline the program and recent progress

  14. The second wave of earthworm invasion: soil organic matter dynamics from the stable isotope perspective

    Science.gov (United States)

    Chang, C.; Szlavecz, K. A.; Bernard, M.; Pitz, S.

    2013-12-01

    Through transformation of plant litter into soil organic matter (SOM) and translocation of ingested organic material among different soil depths, soil organisms, especially earthworms, are one of the major factors affecting SOM dynamics. In North America temperate soil, historical human activity has lead to invasion of European earthworms into habitats that were previously earthworm-free or inhabited only by native species. By consuming leaf litter and SOM, burrowing, and casting, invasive earthworms have been known for reducing the understory vegetation and leaf litter layer while increasing the thickness of organic soil, causing changes in the soil habitat and the distribution of SOM. Recently, another group of invasive earthworm, namely Amynthas from Asia, has been reported invading habitats already dominated by European species, causing a 'second wave of invasion' where the soil ecosystem, already modified by European species, is going through another transition. The mechanisms through which these functionally (ecologically) different species affect C and N transformation could be better understood by tracing the carbon and nitrogen derived from 13C- and 15N-labeled leaf litter into earthworm tissues and SOM. The objective of this study is to understand how earthworm species that differ ecologically, including the Asian Amynthas, interact with each other and how these interactions affect SOM dynamics. We hypothesized that 1) species feeding on different food resources will have different isotopic signature and their tissue 13C and 15N values will change due to facilitation or interspecific competition on food resources, and 2) the short-term fate of litter-derived carbon differs depending on the presence or absence of different earthworm species. These hypotheses were tested by field sampling and lab mesocosm experiments using 13C and 15N double-enriched Tulip Poplar leaf litter (mean 13C = 124‰, mean 15N = 1667‰) produced from tree saplings growing in an

  15. Effects of temperature and isotopic substitution on electron attachment dynamics of guanine–cytosine base pair: Ring-polymer and classical molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Minoshima, Yusuke; Seki, Yusuke [Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570 (Japan); Takayanagi, Toshiyuki, E-mail: tako@mail.saitama-u.ac.jp [Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570 (Japan); Shiga, Motoyuki [Center for Computational Science and E-Systems, Japan Atomic Energy Agency, 148-4, Kashiwanoha Campus, 178-4 Wakashiba, Kashiwa, Chiba 277-0871 (Japan)

    2016-06-15

    Highlights: • Dynamics of excess electron attachment to guanine–cytosine base pair. • Ring-polymer and classical molecular dynamics simulations are performed. • Temperature and isotope substitution effects are investigated. - Abstract: The dynamical process of electron attachment to a guanine–cytosine pair in the normal (h-GC) and deuterated (d-GC) forms has been studied theoretically by semiclassical ring-polymer molecular dynamics (RPMD) simulations using the empirical valence bond model. The initially formed dipole-bound anion is converted rapidly to the valence-bound anion within about 0.1 ps in both h-GC and d-GC. However, the subsequent proton transfer in h-GC occurs with a rate five times greater than the deuteron transfer in d-GC. The change of rates with isotopic substitution and temperature variation in the RPMD simulations are quantitatively and qualitatively different from those in the classical molecular dynamics (MD) simulations, demonstrating the importance of nuclear quantum effects on the dynamics of this system.

  16. Effects of temperature and isotopic substitution on electron attachment dynamics of guanine–cytosine base pair: Ring-polymer and classical molecular dynamics simulations

    International Nuclear Information System (INIS)

    Minoshima, Yusuke; Seki, Yusuke; Takayanagi, Toshiyuki; Shiga, Motoyuki

    2016-01-01

    Highlights: • Dynamics of excess electron attachment to guanine–cytosine base pair. • Ring-polymer and classical molecular dynamics simulations are performed. • Temperature and isotope substitution effects are investigated. - Abstract: The dynamical process of electron attachment to a guanine–cytosine pair in the normal (h-GC) and deuterated (d-GC) forms has been studied theoretically by semiclassical ring-polymer molecular dynamics (RPMD) simulations using the empirical valence bond model. The initially formed dipole-bound anion is converted rapidly to the valence-bound anion within about 0.1 ps in both h-GC and d-GC. However, the subsequent proton transfer in h-GC occurs with a rate five times greater than the deuteron transfer in d-GC. The change of rates with isotopic substitution and temperature variation in the RPMD simulations are quantitatively and qualitatively different from those in the classical molecular dynamics (MD) simulations, demonstrating the importance of nuclear quantum effects on the dynamics of this system.

  17. Cermet Coatings for Solar Stirling Space Power

    Science.gov (United States)

    Jaworske, Donald A.; Raack, Taylor

    2004-01-01

    Cermet coatings, molecular mixtures of metal and ceramic are being considered for the heat inlet surface of a solar Stirling space power converter. This paper will discuss the solar absorption characteristics of as-deposited cermet coatings as well as the solar absorption characteristics of the coatings after heating. The role of diffusion and island formation, during the deposition process and during heating will also be discussed.

  18. Stirling engine with air working fluid

    Science.gov (United States)

    Corey, John A.

    1985-01-01

    A Stirling engine capable of utilizing air as a working fluid which includes a compact heat exchange module which includes heating tube units, regenerator and cooler positioned about the combustion chamber. This arrangement has the purpose and effect of allowing the construction of an efficient, high-speed, high power-density engine without the use of difficult to seal light gases as working fluids.

  19. Optimization of an irreversible Stirling regenerative cycle

    International Nuclear Information System (INIS)

    Aragón-González, G; Cano-Bianco, M; León-Galicia, A; Rivera-Camacho, J M

    2015-01-01

    In this work a Stirling regenerative cycle with some irreversibilities is analyzed. The analyzed irreversibilities are located at the heat exchangers. They receive a finite amount of heat and heat leakage occurs between both reservoirs. Using this model, power and the efficiency at maximum power are obtained. Some optimal design parameters for the exchanger heat areas and thermal conductances are presented. The relation between the power, efficiency and the results obtained are shown graphically

  20. Stirling Engine With Radial Flow Heat Exchangers

    Science.gov (United States)

    Vitale, N.; Yarr, George

    1993-01-01

    Conflict between thermodynamical and structural requirements resolved. In Stirling engine of new cylindrical configuration, regenerator and acceptor and rejector heat exchangers channel flow of working gas in radial direction. Isotherms in regenerator ideally concentric cylinders, and gradient of temperature across regenerator radial rather than axial. Acceptor and rejector heat exchangers located radially inward and outward of regenerator, respectively. Enables substantial increase in power of engine without corresponding increase in diameter of pressure vessel.

  1. Reliability Issues in Stirling Radioisotope Power Systems

    Science.gov (United States)

    Schreiber, Jeffrey; Shah, Ashwin

    2005-01-01

    Stirling power conversion is a potential candidate for use in a Radioisotope Power System (RPS) for space science missions because it offers a multifold increase in the conversion efficiency of heat to electric power and reduced requirement of radioactive material. Reliability of an RPS that utilizes Stirling power conversion technology is important in order to ascertain long term successful performance. Owing to long life time requirement (14 years), it is difficult to perform long-term tests that encompass all the uncertainties involved in the design variables of components and subsystems comprising the RPS. The requirement for uninterrupted performance reliability and related issues are discussed, and some of the critical areas of concern are identified. An overview of the current on-going efforts to understand component life, design variables at the component and system levels, and related sources and nature of uncertainties are also discussed. Current status of the 110 watt Stirling Radioisotope Generator (SRG110) reliability efforts is described. Additionally, an approach showing the use of past experience on other successfully used power systems to develop a reliability plan for the SRG110 design is outlined.

  2. The Alaska Water Isotope Network (AKWIN): Precipitation, lake, river and stream dynamics

    Science.gov (United States)

    Rogers, M.; Welker, J. M.; Toohey, R.

    2011-12-01

    The hydrologic cycle is central to the structure and function of northern landscapes. The movement of water creates interactions between terrestrial, aquatic, marine and atmospheric processes. Understanding the processes and the spatial patterns that govern the isotopic (δ18O & δD) characteristics of the hydrologic cycle is especially important today as: a) modern climate/weather-isotope relations allow for more accurate interpretation of climate proxies and the calibration of atmospheric models, b) water isotopes facilitate understanding the role of storm tracks in regulating precipitation isotopic variability, c) water isotopes allow for estimates of glacial melt water inputs into aquatic systems, d) water isotopes allow for quantification of surface and groundwater interactions, e) water isotopes allow for quantification of permafrost meltwater use by plant communities, f) water isotopes aid in migratory bird forensics, g) water isotopes are critical to estimating field metabolic rates, h) water isotopes allow for crop and diet forensics and i) water isotopes can provide insight into evaporation and transpiration processes. As part of a new NSF MRI project at the Environment and Natural Resources Institute (ENRI) at the University of Alaska Anchorage and as an extension of the US Network for Isotopes in Precipitation (USNIP); we are forming AKWIN. The network will utilize long-term weekly sampling at Denali National Park and Caribou Poker Creek Watershed (USNIP sites-1989 to present), regular sampling across Alaska involving land management agencies (USGS, NPS, USFWS, EPA), educators, volunteers and citizen scientists, UA extended campuses, individual research projects, opportunistic sampling and published data to construct isoscapes and time series databases and information packages. We will be using a suite of spatial and temporal analysis methods to characterize water isotopes across Alaska and will provide web portals for data products. Our network is

  3. Tests Of A Stirling-Engine Power Converter

    Science.gov (United States)

    Dochat, George

    1995-01-01

    Report describes acceptance tests of power converter consisting of pair of opposed free-piston Stirling engines driving linear alternators. Stirling engines offer potential for extremely long life, high reliability, high efficiency at low hot-to-cold temperature ratios, and relatively low heater-head temperatures.

  4. On-Board Hydrogen Gas Production System For Stirling Engines

    Science.gov (United States)

    Johansson, Lennart N.

    2004-06-29

    A hydrogen production system for use in connection with Stirling engines. The production system generates hydrogen working gas and periodically supplies it to the Stirling engine as its working fluid in instances where loss of such working fluid occurs through usage through operation of the associated Stirling engine. The hydrogen gas may be generated by various techniques including electrolysis and stored by various means including the use of a metal hydride absorbing material. By controlling the temperature of the absorbing material, the stored hydrogen gas may be provided to the Stirling engine as needed. A hydrogen production system for use in connection with Stirling engines. The production system generates hydrogen working gas and periodically supplies it to the Stirling engine as its working fluid in instances where loss of such working fluid occurs through usage through operation of the associated Stirling engine. The hydrogen gas may be generated by various techniques including electrolysis and stored by various means including the use of a metal hydride absorbing material. By controlling the temperature of the absorbing material, the stored hydrogen gas may be provided to the Stirling engine as needed.

  5. Dish/Stirling for Department of Defense applications final report

    Energy Technology Data Exchange (ETDEWEB)

    Diver, R.B.; Menicucci, D.F. [Sandia National Labs., Albuquerque, NM (United States). Energy and Environment Div.

    1997-03-01

    This report describes a Strategic Environmental Research and Development Program (SERDP) project to field a dish/Stirling system at a southwestern US military facility. This project entitled ``Dish/Stirling for DoD Applications`` was started in August 1993 and was completed in September 1996. The project`s objective was to assist military facilities to field and evaluate emerging environmentally sound and potentially economical dish/Stirling technology. Dish/Stirling technology has the potential to produce electricity at competitive costs while at the same time providing a secure and environmentally benign source of power. In accordance with the SERDP charter, this project leveraged a US Department of Energy (DOE) cost-shared project between Sandia National Laboratories and Cummins Power Generation, Inc. (CPG). CPG is a wholly owned subsidiary of Cummins Engine Company, a leading manufacturer of diesel engines. To accomplish this objective, the project called for the installation of a dish/Stirling system at a military facility to establish first-hand experience in the operation of a dish/Stirling system. To scope the potential DoD market for dish/Stirling technology and to identify the site for the demonstration, a survey of southwestern US military facilities was also conducted. This report describes the project history, the Cummins dish/Stirling system, results from the military market survey, and the field test results.

  6. Ross-Stirling engines: Variations on a theme

    Energy Technology Data Exchange (ETDEWEB)

    Walker, G; Fauvel, R

    1986-01-01

    A new mechanism called the Ross linkage offers the prospect for compact, lightweight, long-lived, relatively low-cost, Stirling engines with excellent prospects for early commercial developed for various applications. Ross-Stirling engines are unusually compact, with installation envelope about one-third of conventional engines, piston side forces are virtually eliminated facilitating the use of dry lubricated or close tolerance, gas lubricated seals and the linkage geometry automatically favors the large bore/short ratios preferred for Stirling engines. The linkage is simple to make with few moving parts so that cost is relatively low. Various potential or actual embodiments of Ross-Stirling engines are reviewed including Stirling-Stirling gas-fired heat pumps, multicylinder power systems and cryocoolers. The system has sufficient flexibility to readily accommodate widely disparate piston stroke and cylinder diameters. Most work has been done so far with two-piston Stirling engines but the same linkage may be adopted for piston-displacer Stirling engines. 6 refs., 10 figs.

  7. Comparison of isotopic turnover dynamics in two different muscles of a coral reef fish during the settlement phase

    Directory of Open Access Journals (Sweden)

    Laura Gajdzik

    2015-09-01

    Full Text Available The temporal variation in carbon and nitrogen isotopic compositions (noted as δ13C and δ15N was investigated in the convict surgeonfish (Acanthurus triostegus at Moorea (French Polynesia. Over a period of 24 days, juveniles were reared in aquaria and subjected to two different feeding treatments: granules or algae. The dynamics of δ13C and δ15N in two muscles (the adductor mandibulae complex and the epaxial musculature having different functions were compared. At the end of experiments, a steady-state isotopic system in each muscle tissue was not reached. Especially for the algal treatment, we found different patterns of variation in isotopic compositions over time between the two muscles. The turnovers of δ13C showed opposite trends for each muscle but differences are mitigated by starvation and by the metamorphosis. Our study highlighted that the metabolism of coral reef fish may be subjected to catabolism or anabolism of non-protein precursors at settlement, inducing variation in isotopic compositions that are not linked to diet change.

  8. 5-kWe Free-piston Stirling Engine Convertor

    Science.gov (United States)

    Chapman, Peter A.; Vitale, Nicholas A.; Walter, Thomas J.

    2008-01-01

    The high reliability, long life, and efficient operation of Free-Piston Stirling Engines (FPSEs) make them an attractive power system to meet future space power requirements with less mass, better efficiency, and less total heat exchanger area than other power convertor options. FPSEs are also flexible in configuration as they can be coupled with many potential heat sources and various heat input systems, heat rejection systems, and power management and distribution systems. Development of a 5-kWe Stirling Convertor Assembly (SCA) is underway to demonstrate the viability of an FPSE for space power. The design is a scaled-down version of the successful 12.5-kWe Component Test Power Converter (CTPC) developed under NAS3-25463. The ultimate efficiency target is 25% overall convertor efficiency (electrical power out over heat in). For the single cylinder prototype now in development, cost and time constraints required use of economical and readily available materials (steel versus beryllium) and components (a commercially available linear alternator) and thus lower efficiency. The working gas is helium at 150 bar mean pressure. The design consists of a displacer suspended on internally pumped gas bearings and a power piston/alternator supported on flexures. Non-contacting clearance seals are used between internal volumes. Heat to and from the prototype convertor is done via pumped liquid loops passing through shell and tube heat exchangers. The preliminary and detail designs of the convertor, controller, and support systems (heating loop, cooling loop, and helium supply system) are complete and all hardware is on order. Assembly and test of the prototype at Foster- Miller is planned for early 2008, when work will focus on characterizing convertor dynamics and steady-state operation to determine maximum power output and system efficiency. The device will then be delivered to Auburn University where assessments will include start-up and shutdown characterization and

  9. Vibration-free stirling cryocooler for high definition microscopy

    Science.gov (United States)

    Riabzev, S. V.; Veprik, A. M.; Vilenchik, H. S.; Pundak, N.; Castiel, E.

    2009-12-01

    The normal operation of high definition Scanning Electronic and Helium Ion microscope tools often relies on maintaining particular components at cryogenic temperatures. This has traditionally been accomplished by using liquid coolants such as liquid Nitrogen. This inherently limits the useful temperature range to above 77 K, produces various operational hazards and typically involves elevated ownership costs, inconvenient logistics and maintenance. Mechanical coolers, over-performing the above traditional method and capable of delivering required (even below 77 K) cooling to the above cooled components, have been well-known elsewhere for many years, but their typical drawbacks, such as high purchasing cost, cooler size, low reliability and high power consumption have so far prevented their wide-spreading. Additional critical drawback is inevitable degradation of imagery performance originated from the wideband vibration export as typical for the operation of the mechanical cooler incorporating numerous movable components. Recent advances in the development of reliable, compact, reasonably priced and dynamically quiet linear cryogenic coolers gave rise to so-called "dry cooling" technologies aimed at eventually replacing the traditional use of outdated liquid Nitrogen cooling facilities. Although much improved these newer cryogenic coolers still produce relatively high vibration export which makes them incompatible with modern high definition microscopy tools. This has motivated further research activity towards developing a vibration free closed-cycle mechanical cryocooler. The authors have successfully adapted the standard low vibration Stirling cryogenic refrigerator (Ricor model K535-LV) delivering 5 W@40 K heat lift for use in vibration-sensitive high definition microscopy. This has been achieved by using passive mechanical counterbalancing of the main portion of the low frequency vibration export in combination with an active feed-forward multi

  10. Single-piston alternative to Stirling engines

    International Nuclear Information System (INIS)

    Glushenkov, Maxim; Sprenkeler, Martin; Kronberg, Alexander; Kirillov, Valeriy

    2012-01-01

    Highlights: ► Thermodynamic analysis of an unconventional heat engine. ► The engine has a number of advantages compared to state-of-the-art Stirling engines. ► The engine can to be fuelled with “difficult” fuels and used for micro-CHP systems. ► The energy conversion efficiency can be as high as 40–50%. ► A prototype of the engine was demonstrated. -- Abstract: Thermodynamic analysis of an unconventional heat engine was performed. The engine studied has a number of advantages compared to state-of-the-art Stirling engines. The main advantage of the engine proposed is its simplicity. A power piston is integral with a displacer and a heat regenerator. It allows solving the problem of the high-temperature sealing of the piston and the displacer typical of all types of Stirling engines. In addition the design proposed provides ideal use of the displacer volume eliminating heat losses from outside gas circuit. Both strokes of the piston are working ones in contrary to any other types of piston engines. The engine can be considered as maintenance-free as it has no piston rings or any other rubbing components requiring lubrication. The only seal is contactless and wear free. It is located in the cold part of the cylinder. As a result the leakage rate in operation can be one-two orders of magnitude as small as that in Stirling engines. Balancing of the engine is much easy compared to Stirling engines with two reciprocating masses because of the only moving part inside the engine cylinder. The engine suits ideally to be fuelled with “difficult” fuels such as bio oil and can be used as a prime mover for micro-CHP systems. The thermodynamic model developed incorporates non-ideal features of the cycle, such as specific regenerator efficiency, dead volumes and other geometrical parameters of the engine. The model shows that the energy efficiency is highly sensitive to regenerator performance. For realistic geometric and operating parameters and the

  11. Coupled sulfur isotopic and chemical mass transfer modeling: Approach and application to dynamic hydrothermal processes

    International Nuclear Information System (INIS)

    Janecky, D.R.

    1988-01-01

    A computational modeling code (EQPSreverse arrowS) has been developed to examine sulfur isotopic distribution pathways coupled with calculations of chemical mass transfer pathways. A post processor approach to EQ6 calculations was chosen so that a variety of isotopic pathways could be examined for each reaction pathway. Two types of major bounding conditions were implemented: (1) equilibrium isotopic exchange between sulfate and sulfide species or exchange only accompanying chemical reduction and oxidation events, and (2) existence or lack of isotopic exchange between solution species and precipitated minerals, parallel to the open and closed chemical system formulations of chemical mass transfer modeling codes. All of the chemical data necessary to explicitly calculate isotopic distribution pathways is generated by most mass transfer modeling codes and can be input to the EQPS code. Routines are built in to directly handle EQ6 tabular files. Chemical reaction models of seafloor hydrothermal vent processes and accompanying sulfur isotopic distribution pathways illustrate the capabilities of coupling EQPSreverse arrowS with EQ6 calculations, including the extent of differences that can exist due to the isotopic bounding condition assumptions described above. 11 refs., 2 figs

  12. Stable carbon isotope depth profiles and soil organic carbon dynamics in the lower Mississippi Basin

    Science.gov (United States)

    Wynn, J.G.; Harden, J.W.; Fries, T.L.

    2006-01-01

    Analysis of depth trends of 13C abundance in soil organic matter and of 13C abundance from soil-respired CO2 provides useful indications of the dynamics of the terrestrial carbon cycle and of paleoecological change. We measured depth trends of 13C abundance from cropland and control pairs of soils in the lower Mississippi Basin, as well as the 13C abundance of soil-respired CO2 produced during approximately 1-year soil incubation, to determine the role of several candidate processes on the 13C depth profile of soil organic matter. Depth profiles of 13C from uncultivated control soils show a strong relationship between the natural logarithm of soil organic carbon concentration and its isotopic composition, consistent with a model Rayleigh distillation of 13C in decomposing soil due to kinetic fractionation during decomposition. Laboratory incubations showed that initially respired CO 2 had a relatively constant 13C content, despite large differences in the 13C content of bulk soil organic matter. Initially respired CO2 was consistently 13C-depleted with respect to bulk soil and became increasingly 13C-depleted during 1-year, consistent with the hypothesis of accumulation of 13C in the products of microbial decomposition, but showing increasing decomposition of 13C-depleted stable organic components during decomposition without input of fresh biomass. We use the difference between 13C / 12C ratios (calculated as ??-values) between respired CO 2 and bulk soil organic carbon as an index of the degree of decomposition of soil, showing trends which are consistent with trends of 14C activity, and with results of a two-pooled kinetic decomposition rate model describing CO2 production data recorded during 1 year of incubation. We also observed inconsistencies with the Rayleigh distillation model in paired cropland soils and reasons for these inconsistencies are discussed. ?? 2005 Elsevier B.V. All rights reserved.

  13. Stirling engines for biomass – what is the problem?

    DEFF Research Database (Denmark)

    Carlsen, Henrik

    2005-01-01

    The External combustion of the Stirling engine makes it very attractive for small-scale Combined Heat and Power (CHP) plants using bio-fuels. Especially wood chips are an attractive fuel because of the high melting point and the low content of ash. Unfortunately, it is more complicated than...... expected to use bio-fuels for a Stirling engine. The high temperature in the hot heat exchanger transferring heat from the combustion to the Stirling engine combined with the low heating value of the fuel reduce the obtainable efficiency of the plant. The limitations of the combustion temperature in order...... to avoid melted ash in the combustion chamber decrease the obtainable efficiency even further. If a Stirling engine, which has an efficiency of 28,5% using natural gas, is converted into utilization of bio-fuel, the efficiency will decrease to 17,5%. Another problem for utilization of bio-fuels in Stirling...

  14. Overview of Stirling Technology Research at NASA Glenn Research Center

    Science.gov (United States)

    Wilson, Scott D.; Schifer, Nicholas A.; Williams, Zachary D.; Metscher, Jonathan F.

    2016-01-01

    Stirling Radioisotope Power Systems (RPSs) are under development to provide power on future space science missions where robotic spacecraft will orbit, fly by, land, or rove using less than a quarter of the plutonium the currently available RPS uses to produce about the same power. NASA Glenn Research Center's newly formulated Stirling Cycle Technology Development Project (SCTDP) continues development of Stirling-based systems and subsystems, which include a flight-like generator and related housing assembly, controller, and convertors. The project also develops less mature technologies under Stirling Technology Research, with a focus on demonstration in representative environments to increase the technology readiness level (TRL). Matured technologies are evaluated for selection in future generator designs. Stirling Technology Research tasks focus on a wide variety of objectives, including increasing temperature capability to enable new environments, reducing generator mass and/or size, improving reliability and system fault tolerance, and developing alternative designs. The task objectives and status are summarized.

  15. Hafnium isotope evidence for a transition in the dynamics of continental growth 3.2 Gyr ago.

    Science.gov (United States)

    Næraa, T; Scherstén, A; Rosing, M T; Kemp, A I S; Hoffmann, J E; Kokfelt, T F; Whitehouse, M J

    2012-05-30

    Earth's lithosphere probably experienced an evolution towards the modern plate tectonic regime, owing to secular changes in mantle temperature. Radiogenic isotope variations are interpreted as evidence for the declining rates of continental crustal growth over time, with some estimates suggesting that over 70% of the present continental crustal reservoir was extracted by the end of the Archaean eon. Patterns of crustal growth and reworking in rocks younger than three billion years (Gyr) are thought to reflect the assembly and break-up of supercontinents by Wilson cycle processes and mark an important change in lithosphere dynamics. In southern West Greenland numerous studies have, however, argued for subduction settings and crust growth by arc accretion back to 3.8 Gyr ago, suggesting that modern-day tectonic regimes operated during the formation of the earliest crustal rock record. Here we report in situ uranium-lead, hafnium and oxygen isotope data from zircons of basement rocks in southern West Greenland across the critical time period during which modern-like tectonic regimes could have initiated. Our data show pronounced differences in the hafnium isotope-time patterns across this interval, requiring changes in the characteristics of the magmatic protolith. The observations suggest that 3.9-3.5-Gyr-old rocks differentiated from a >3.9-Gyr-old source reservoir with a chondritic to slightly depleted hafnium isotope composition. In contrast, rocks formed after 3.2 Gyr ago register the first additions of juvenile depleted material (that is, new mantle-derived crust) since 3.9 Gyr ago, and are characterized by striking shifts in hafnium isotope ratios similar to those shown by Phanerozoic subduction-related orogens. These data suggest a transitional period 3.5-3.2 Gyr ago from an ancient (3.9-3.5 Gyr old) crustal evolutionary regime unlike that of modern plate tectonics to a geodynamic setting after 3.2 Gyr ago that involved juvenile crust generation by plate

  16. Study of soil erosion dynamics on the arable lands of Lublin Upland using isotope techniques (137Cs)

    International Nuclear Information System (INIS)

    Zglobicki, W.; Reszka, M.

    2002-01-01

    One of the consequences of agricultural activity are changes of significant element of the environment, that is terrain relief. Since sixties the radioactive isotope of cesium, 137 Cs, is applied in the examination of the dynamics of the erosion processes. This method is based on the idea that the circulation of this isotope in the environment accompanies to physical transport of soil. Studies proved that cesium is firmly bond by adsorption complex of the soil. Chemical and biochemical processes have limited influence on the transportation of the cesium. By the examination of the horizontal changes of the total cesium activity one can determine a type and intensity of the processes responsible for its migration and thus the migration of the soil particles

  17. Isotopic dynamics of C, O and U in soils and their relation to climate

    OpenAIRE

    Oerter, Erik

    2015-01-01

    The development of soil is driven by environmental conditions, and soil properties are reflective of those conditions. Pedogenic carbonate is widespread in arid and semi-arid soils and its stable C and O isotope composition is often used as a paleoclimate indicator. However, questions remain about the precise meaning of those signals, and most importantly the season(s) that the isotopic composition most closely reflects. Chapter 1 examines the soil conditions that lead to carbonate formation...

  18. The 25 kWe solar thermal Stirling hydraulic engine system: Conceptual design

    Science.gov (United States)

    White, Maurice; Emigh, Grant; Noble, Jack; Riggle, Peter; Sorenson, Torvald

    1988-01-01

    The conceptual design and analysis of a solar thermal free-piston Stirling hydraulic engine system designed to deliver 25 kWe when coupled to a 11 meter test bed concentrator is documented. A manufacturing cost assessment for 10,000 units per year was made. The design meets all program objectives including a 60,000 hr design life, dynamic balancing, fully automated control, more than 33.3 percent overall system efficiency, properly conditioned power, maximum utilization of annualized insolation, and projected production costs. The system incorporates a simple, rugged, reliable pool boiler reflux heat pipe to transfer heat from the solar receiver to the Stirling engine. The free-piston engine produces high pressure hydraulic flow which powers a commercial hydraulic motor that, in turn, drives a commercial rotary induction generator. The Stirling hydraulic engine uses hermetic bellows seals to separate helium working gas from hydraulic fluid which provides hydrodynamic lubrication to all moving parts. Maximum utilization of highly refined, field proven commercial components for electric power generation minimizes development cost and risk.

  19. The Development of a Control System for a 5 Kilowatt Free Piston Stirling Engine Convertor

    Science.gov (United States)

    Kirby, Raymond L.; Vitale, Nick

    2008-01-01

    The new NASA Vision for Exploration, announced by President Bush in January 2004, proposes an ambitious program that plans to return astronauts to the moon by the 2018 time frame. A recent NASA study entitled "Affordable Fission Surface Power Study" recommended a 40 kWe, 900 K, NaK-cooled, Stirling convertors for 2020 launch. Use of two of the nominal 5 kW convertors allows the system to be dynamically balanced. A group of four dual-convertor combinations that would yield 40 kWe can be tested to validate the viability of Stirling technology for space fission surface power systems. The work described in this paper deals specifically with the control system for the 5 kW convertor described in the preceding paragraph. This control system is responsible for maintaining piston stroke to a setpoint in the presence of various disturbances including electrical load variations. Pulse starting of the Free Piston Stirling Engine (FPSE) convertor is also an inherent part of such a control system. Finally, the ability to throttle the engine to match the required output power is discussed in terms of setpoint control. Several novel ideas have been incorporated into the piston stroke control strategy that will engender a stable response to disturbances in the presence of midpoint drift while providing useful data regarding the position of both the power piston and displacer.

  20. Development of a Transient Model of a Stirling-Based CHP System

    Directory of Open Access Journals (Sweden)

    Antón Cacabelos

    2013-06-01

    Full Text Available Although the Stirling engine was invented in 1816, this heat engine still continues to be investigated due to the variety of energy sources that can be used to power it (e.g., solar energy, fossil fuels, biomass, and geothermal energy. To study the performance of these machines, it is necessary to develop and simulate models under different operating conditions. In this paper, we present a one-dimensional dynamic model based on components from Trnsys: principally, a lumped mass and a heat exchanger. The resulting model is calibrated using GenOpt. Furthermore, the obtained model can be used to simulate the machine both under steady-state operation and during a transient response. The results provided by the simulations are compared with data measured in a Stirling engine that has been subjected to different operating conditions. This comparison shows good agreement, indicating that the model is an appropriate method for transient thermal simulations. This new proposed model requires few configuration parameters and is therefore easily adaptable to a wide range of commercial models of Stirling engines. A detailed analysis of the system results reveals that the power is directly related to the difference of temperatures between the hot and cold sources during the transient and steady-state processes.

  1. Development of a Power Electronics Controller for the Advanced Stirling Radioisotope Generator

    Science.gov (United States)

    Leland, Douglas K.; Priest, Joel F.; Keiter, Douglas E.; Schreiber, Jeffrey G.

    2008-01-01

    Under a U.S. Department of Energy program for radioisotope power systems, Lockheed Martin is developing an Engineering Unit of the Advanced Stirling Radioisotope Generator (ASRG). This is an advanced version of the previously reported SRG110 generator. The ASRG uses Advanced Stirling Convertors (ASCs) developed by Sunpower Incorporated under a NASA Research Announcement contract. The ASRG makes use of a Stirling controller based on power electronics that eliminates the tuning capacitors. The power electronics controller synchronizes dual-opposed convertors and maintains a fixed frequency operating point. The controller is single-fault tolerant and uses high-frequency pulse width modulation to create the sinusoidal currents that are nearly in phase with the piston velocity, eliminating the need for large series tuning capacitors. Sunpower supports this effort through an extension of their controller development intended for other applications. Glenn Research Center (GRC) supports this effort through system dynamic modeling, analysis and test support. The ASRG design arrived at a new baseline based on a system-level trade study and extensive feedback from mission planners on the necessity of single-fault tolerance. This paper presents the baseline design with an emphasis on the power electronics controller detailed design concept that will meet space mission requirements including single fault tolerance.

  2. The design of a small linear-resonant, split Stirling cryogenic refrigerator compressor

    Science.gov (United States)

    Ackermann, R. A.

    1985-01-01

    The development of a small linear-resonant compressor for use in a 1/4-watt, 78K, split Stirling cryogenic refrigerator is discussed. The compressor contains the following special features: (1) a permanent-magnet linear motor; (2) resonant dynamics; (3) dynamic balancing; and (4) a close-clearance seal between the compressor piston and cylinder. This paper describes the design of the compressor, and presents component test data and system test data for the compressor driving a 1/4-watt expander.

  3. Research on Control Strategy of Free-Piston Stirling Power Generating System

    Directory of Open Access Journals (Sweden)

    Jigui Zheng

    2017-10-01

    Full Text Available As a clean and fuel adaptive alternative power plant, the Stirling power generating system has drawn attention of experts and scholars in the energy field. In practical application, the instability of free-piston Stirling power generating system caused by abrupt load change is an inevitable problem. Thus, methods to improve the output frequency response and stability of the free-piston Stirling power generating system are necessary. The model of free-piston Stirling power generating system is built by isothermal analysis firstly, and the initial control strategy based on given voltage system is put forward. To further improve the performance of power system, a current feedback decoupling control strategy is proposed, and the mathematical model is established. The influence of full decoupled quadrature-direct (d-q axis currents is analyzed with respect to the output voltage adjusting time and fluctuation amplitude under the variations of piston displacement and output load. The simulation results show that the system performance is significantly improved, but the dynamic regulation lags caused by the decoupled current control still exist. To solve this problem and improve the performance of decoupled-state feedback current control that relies on parameter accuracy, internal model control based on sliding mode (IMC-SM current decoupling control strategy is proposed, the system model is established, and then the performance of voltage ripple in generating mode is improved. Finally, the test bench is built, and the steady state and transient voltage control performances are tested. The feasibility and priority of the control strategy is verified by experiment and simulation results.

  4. Soil water stable isotopes reveal evaporation dynamics at the soil–plant–atmosphere interface of the critical zone

    Directory of Open Access Journals (Sweden)

    M. Sprenger

    2017-07-01

    Full Text Available Understanding the influence of vegetation on water storage and flux in the upper soil is crucial in assessing the consequences of climate and land use change. We sampled the upper 20 cm of podzolic soils at 5 cm intervals in four sites differing in their vegetation (Scots Pine (Pinus sylvestris and heather (Calluna sp. and Erica Sp and aspect. The sites were located within the Bruntland Burn long-term experimental catchment in the Scottish Highlands, a low energy, wet environment. Sampling took place on 11 occasions between September 2015 and September 2016 to capture seasonal variability in isotope dynamics. The pore waters of soil samples were analyzed for their isotopic composition (δ2H and δ18O with the direct-equilibration method. Our results show that the soil waters in the top soil are, despite the low potential evaporation rates in such northern latitudes, kinetically fractionated compared to the precipitation input throughout the year. This fractionation signal decreases within the upper 15 cm resulting in the top 5 cm being isotopically differentiated to the soil at 15–20 cm soil depth. There are significant differences in the fractionation signal between soils beneath heather and soils beneath Scots pine, with the latter being more pronounced. But again, this difference diminishes within the upper 15 cm of soil. The enrichment in heavy isotopes in the topsoil follows a seasonal hysteresis pattern, indicating a lag time between the fractionation signal in the soil and the increase/decrease of soil evaporation in spring/autumn. Based on the kinetic enrichment of the soil water isotopes, we estimated the soil evaporation losses to be about 5 and 10 % of the infiltrating water for soils beneath heather and Scots pine, respectively. The high sampling frequency in time (monthly and depth (5 cm intervals revealed high temporal and spatial variability of the isotopic composition of soil waters, which can be critical

  5. The 1988 overview of free-piston Stirling technology for space power at the NASA Lewis Research Center

    Science.gov (United States)

    Slaby, Jack G.

    1988-01-01

    The completion of the Space Power Demonstrator Engine (SPDE) testing is discussed, terminating with the generation of 25 kW of engine power from a dynamically-balanced opposed-piston Stirling engine at a temperature ratio of 2.0. Engine efficiency was greater than 22 percent. The SPDE recently was divided into 2 separate single cylinder engines, Space Power Research Engine (SPRE), that serves as test beds for the evaluation of key technology disciplines, which include hydrodynamic gas bearings, high efficiency linear alternators, space qualified heat pipe heat exchangers, oscillating flow code validation, and engine loss understanding. The success of the SPDE at 650 K has resulted in a more ambitious Stirling endeavor, the design, fabrication, test, and evaluation of a designed-for-space 25 kW per cylinder Stirling Space Engine (SSE) to operate at a hot metal temperature of 1050 K using superalloy materials. This design is a low temperature confirmation of the 1300 K design. It is the 1300 K free-piston Stirling power conversion system that is the ultimate goal. The first two phases of this program, the 650 K SPDE and the 1050 K SSE are emphasized.

  6. Non-ideal Stirling engine thermodynamic model suitable for the integration into overall energy systems

    International Nuclear Information System (INIS)

    Araoz, Joseph A.; Salomon, Marianne; Alejo, Lucio; Fransson, Torsten H.

    2014-01-01

    The reliability of modelling and simulation of energy systems strongly depends on the prediction accuracy of each system component. This is the case of Stirling engine-based systems, where an accurate modelling of the engine performance is very important to understand the overall system behaviour. In this sense, many Stirling engine analyses with different approaches have been already developed. However, there is a lack of Stirling engine models suitable for the integration into overall system simulations. In this context, this paper aims to develop a rigorous Stirling engine model that could be easily integrated into combined heat and power schemes for the overall techno-economic analysis of these systems. The model developed considers a Stirling engine with adiabatic working spaces, isothermal heat exchangers, dead volumes, and imperfect regeneration. Additionally, it considers mechanical pumping losses due to friction, limited heat transfer and thermal losses on the heat exchangers. The model is suitable for different engine configurations (alpha beta and gamma engines). It was developed using Aspen Custom Modeller ® (ACM®) as modelling software. The set of equations were solved using ACM ® equation solver for steady-state operation. However, due to the dynamic behaviour of the cycle, a C++ code was integrated to solve iteratively a set of differential equations. This resulted in a cyclic steady-state model that calculates the power output and thermal requirements of the system. The predicted efficiency and power output were compared with the numerical model and the experimental work reported by the NASA Lewis Research Centre for the GPU-3 Stirling engine. This showed average absolute errors around ±4% for the brake power, and ±5% for the brake efficiency at different frequencies. However, the model also showed large errors (±15%) for these calculations at higher frequencies and low pressures. Additional results include the calculation of the cyclic

  7. Particle dynamics study in the wake of Kerguelen Island using thorium isotopes

    International Nuclear Information System (INIS)

    Venchiarutti, C.; Jeandel, C.; Roy-Barman, M.

    2008-01-01

    In the context of the Kerguelen Ocean and Plateau compared Study (KEOPS, 19 January-13 February 2005), particle dynamics were investigated using thorium isotope measurements over and off the Kerguelen plateau. Dissolved and particulate 230 Th and 232 Th samples were collected at nine stations. Dissolved excess 230 Th concentrations ( 230 Th(xs)) vary from 0.5 to 20.8 fg/kg and particulate 230 Th(xs) concentrations from 0.1 to 10.0 fg/kg. Dissolved and particulate 232 Th concentration ranges are 16.8-450.2 pg/kg and 3.8-502.8 pg/kg, respectively. The 230 Th(xs) concentrations increase linearly with depth down to the bottom at most of the plateau stations and down to 1000 m at the off-plateau stations. This linear trend is observed down to the bottom (1550 m) at Kerfix, the open-ocean 'upstream' station located west of the Kerguelen plateau. A simple reversible scavenging model applied to these data allowed the estimation of adsorption rate constant (k 1 ≅ 0.2-0.8 year -1 ), desorption rate constant (k -1 ) ≅ 1-8 year -1 ) and partition coefficients (average K = 0.16 ± 0.07). Calculated particle settling velocities S deduced from this simple model are ca. 500 m/year at most of the plateau stations and 800 m/year at all the off-plateau stations. The plateau settling velocities are relatively low for such a productive site, compared to the surrounding HNLC areas. The difference might reflect the fact that lateral advection is neglected in this model. Taking this advection into account allows the reconstruction of the observed 230 Th(xs) linear distributions, but only if faster settling velocities are considered. This implies that the 1 D model strongly underestimates the settling velocity of the particles. In the deep layers, the occurrence of intense boundary scavenging along the escarpment due to bottom sediment re-suspension and interaction with a nepheloid layer, yielding a removal of similar to 50% of the Th stock along the northwestward transect, is

  8. Update on the NASA GRC Stirling Technology development project

    Science.gov (United States)

    Thieme, Lanny G.; Schreiber, Jeffrey G.

    2001-02-01

    The Department of Energy, NASA Glenn Research Center (GRC), and Stirling Technology Company (STC) are developing a free-piston Stirling convertor for a Stirling radioisotope power system (SRPS) to provide spacecraft on-board electric power for NASA deep space missions. The SRPS has recently been identified for potential use on the Europa Orbiter and Solar Probe Space Science missions. Stirling is also now being considered for unmanned Mars rovers. NASA GRC is conducting an in-house project to assist in developing the Stirling convertor for readiness for space qualification and mission implementation. As part of this continuing effort, the Stirling convertor will be further characterized under launch environment random vibration testing, methods to reduce convertor electromagnetic interference (EMI) will be developed, and an independent performance verification will be completed. Convertor life assessment and permanent magnet aging characterization tasks are also underway. Substitute organic materials for the linear alternator and piston bearing coatings for use in a high radiation environment have been identified and have now been incorporated in Stirling convertors built by STC for GRC. Electromagnetic and thermal finite element analyses for the alternator are also being conducted. This paper discusses the recent results and status for this NASA GRC in-house project. .

  9. The NASA Next Generation Stirling Technology Program Overview

    Science.gov (United States)

    Schreiber, J. G.; Shaltens, R. K.; Wong, W. A.

    2005-12-01

    NASAs Science Mission Directorate is developing the next generation Stirling technology for future Radioisotope Power Systems (RPS) for surface and deep space missions. The next generation Stirling convertor is one of two advanced power conversion technologies currently being developed for future NASA missions, and is capable of operating for both planetary atmospheres and deep space environments. The Stirling convertor (free-piston engine integrated with a linear alternator) produces about 90 We(ac) and has a specific power of about 90 We/kg. Operating conditions of Thot at 850 degree C and Trej at 90 degree C results in the Stirling convertor estimated efficiency of about 40 per cent. Using the next generation Stirling convertor in future RPS, the "system" specific power is estimated at 8 We/kg. The design lifetime is three years on the surface of Mars and fourteen years in deep space missions. Electrical power of about 160 We (BOM) is produced by two (2) free-piston Stirling convertors heated by two (2) General Purpose Heat Source (GPHS) modules. This development is being performed by Sunpower, Athens, OH with Pratt & Whitney, Rocketdyne, Canoga Park, CA under contract to Glenn Research Center (GRC), Cleveland, Ohio. GRC is guiding the independent testing and technology development for the next generation Stirling generator.

  10. Stability analysis of free piston Stirling engines

    Science.gov (United States)

    Bégot, Sylvie; Layes, Guillaume; Lanzetta, François; Nika, Philippe

    2013-03-01

    This paper presents a stability analysis of a free piston Stirling engine. The model and the detailed calculation of pressures losses are exposed. Stability of the machine is studied by the observation of the eigenvalues of the model matrix. Model validation based on the comparison with NASA experimental results is described. The influence of operational and construction parameters on performance and stability issues is exposed. The results show that most parameters that are beneficial for machine power seem to induce irregular mechanical characteristics with load, suggesting that self-sustained oscillations could be difficult to maintain and control.

  11. Double acting stirling engine phase control

    Science.gov (United States)

    Berchowitz, David M.

    1983-01-01

    A mechanical device for effecting a phase change between the expansion and compression volumes of a double-acting Stirling engine uses helical elements which produce opposite rotation of a pair of crankpins when a control rod is moved, so the phase between two pairs of pistons is changed by +.psi. and the phase between the other two pairs of pistons is changed by -.psi.. The phase can change beyond .psi.=90.degree. at which regenerative braking and then reversal of engine rotation occurs.

  12. A high performance thermoacoustic Stirling-engine

    Energy Technology Data Exchange (ETDEWEB)

    Tijani, M.E.H.; Spoelstra, S. [Energy research Centre of the Netherlands (ECN), PO Box 1, 1755 ZG Petten (Netherlands)

    2011-11-10

    In thermoacoustic systems heat is converted into acoustic energy and vice versa. These systems use inert gases as working medium and have no moving parts which makes the thermoacoustic technology a serious alternative to produce mechanical or electrical power, cooling power, and heating in a sustainable and environmentally friendly way. A thermoacoustic Stirling heat engine is designed and built which achieves a record performance of 49% of the Carnot efficiency. The design and performance of the engine is presented. The engine has no moving parts and is made up of few simple components.

  13. Stirling cycle engines inner workings and design

    CERN Document Server

    Organ, Allan J

    2013-01-01

    Some 200 years after the original invention, internal design of a Stirling engine has come to be considered a specialist task, calling for extensive experience and for access to sophisticated computer modelling. The low parts-count of the type is negated by the complexity of the gas processes by which heat is converted to work. Design is perceived as problematic largely because those interactions are neither intuitively evident, nor capable of being made visible by laboratory experiment. There can be little doubt that the situation stands in the way of wider application of this elegant concep

  14. In-line stirling energy system

    Science.gov (United States)

    Backhaus, Scott N [Espanola, NM; Keolian, Robert [State College, PA

    2011-03-22

    A high efficiency generator is provided using a Stirling engine to amplify an acoustic wave by heating the gas in the engine in a forward mode. The engine is coupled to an alternator to convert heat input to the engine into electricity. A plurality of the engines and respective alternators can be coupled to operate in a timed sequence to produce multi-phase electricity without the need for conversion. The engine system may be operated in a reverse mode as a refrigerator/heat pump.

  15. Isotopic method of testing the dynamics of melt flow through a sedimentation tank

    International Nuclear Information System (INIS)

    Bazaniak, Z.; Chamer, R.; Stec, J.; Przybytniak, W.

    1981-01-01

    The isotopic method of a simultaneous measurement of copper matte and slag flow parameters is discussed. For marking Cu-64 and Zr 95/97, isotopes characterized by various gamma radiation energy are used. The chemical form of copper and zirconium compounds was chosen from the viewpoint of assuring a selective solubility in the tested phases. To interpret the results of isotopic tests, the Wolf-Resnick model was made. The obtained results have confirmed the hypothesis of a possible occurrence of the copper matte flotation effect. In order to reduce of copper uplifted with the shaft slag, a redesigning is suggested of the sedimentation tank that would assure a reduction of the ideal mixing participation and an increase of the zone characterized by the piston flow. (author)

  16. Dynamical barrier and isotope effects in the simplest substitution reaction via Walden inversion mechanism

    Science.gov (United States)

    Zhao, Zhiqiang; Zhang, Zhaojun; Liu, Shu; Zhang, Dong H.

    2017-02-01

    Reactions occurring at a carbon atom through the Walden inversion mechanism are one of the most important and useful classes of reactions in chemistry. Here we report an accurate theoretical study of the simplest reaction of that type: the H+CH4 substitution reaction and its isotope analogues. It is found that the reaction threshold versus collision energy is considerably higher than the barrier height. The reaction exhibits a strong normal secondary isotope effect on the cross-sections measured above the reaction threshold, and a small but reverse secondary kinetic isotope effect at room temperature. Detailed analysis reveals that the reaction proceeds along a path with a higher barrier height instead of the minimum-energy path because the umbrella angle of the non-reacting methyl group cannot change synchronously with the other reaction coordinates during the reaction due to insufficient energy transfer from the translational motion to the umbrella mode.

  17. Ceramic applications in the advanced Stirling automotive engine

    Science.gov (United States)

    Tomazic, W. A.; Cairelli, J. E.

    1978-01-01

    The requirements of the ideal Stirling cycle, as well as basic types of practical engines are described. Advantages, disadvantages, and problem areas of these Stirling engines are discussed. The potential for ceramic components is also considered. Currently ceramics are used in only two areas, the air preheater and insulating tiles between the burner and the heater head. For the advanced Stirling engine to achieve high efficiency and low cost, the principal components are expected to be made from ceramic materials, including the heater head, air preheater, regenerator, the burner and the power piston. Supporting research and technology programs for ceramic component development are briefly described.

  18. Initial testing of a variable-stroke Stirling engine

    Science.gov (United States)

    Thieme, L. G.

    1985-01-01

    In support of the U.S. Department of Energy's Stirling Engine Highway Vehicle Systems Program, NASA Lewis Research Center is evaluating variable-stroke control for Stirling engines. The engine being tested is the Advenco Stirling engine; this engine was manufactured by Philips Research Laboratories of the Netherlands and uses a variable-angle swash-plate drive to achieve variable stroke operation. The engine is described, initial steady-state test data taken at Lewis are presented, a major drive system failure and subsequent modifications are described. Computer simulation results are presented to show potential part-load efficiency gains with variable-stroke control.

  19. Linear hydraulic drive system for a Stirling engine

    Science.gov (United States)

    Walsh, Michael M.

    1984-02-21

    A hydraulic drive system operating from the periodic pressure wave produced by a Stirling engine along a first axis thereof and effecting transfer of power from the Stirling engine to a load apparatus therefor and wherein the movable, or working member of the load apparatus is reciprocatingly driven along an axis substantially at right angles to the first axis to achieve an arrangement of a Stirling engine and load apparatus assembly which is much shorter and the components of the load apparatus more readily accessible.

  20. Potential impacts of Brayton and Stirling cycle engines

    Science.gov (United States)

    Heft, R. C.

    1980-01-01

    Two engine technologies (Brayton cycle and Stirling cycle) are examined for their potential economic impact and fuel utilization. An economic analysis of the expected response of buyers to the attributes of the alternative engines was performed. Hedonic coefficients for vehicle fuel efficiency, performance and size were estimated for domestic cars based upon historical data. The marketplace value of the fuel efficiency enhancement provided by Brayton or Stirling engines was estimated. Under the assumptions of 10 years for plant conversions and 1990 and 1995 as the introduction data for turbine and Stirling engines respectively, the comparative fuel savings and present value of the future savings in fuel costs were estimated.

  1. Loss terms in free-piston Stirling engine models

    Science.gov (United States)

    Gordon, Lloyd B.

    1992-01-01

    Various models for free piston Stirling engines are reviewed. Initial models were developed primarily for design purposes and to predict operating parameters, especially efficiency. More recently, however, such models have been used to predict engine stability. Free piston Stirling engines have no kinematic constraints and stability may not only be sensitive to the load, but also to various nonlinear loss and spring constraints. The present understanding is reviewed of various loss mechanisms for free piston Stirling engines and how they have been incorporated into engine models is discussed.

  2. Thermoacoustic refrigerators and engines comprising cascading stirling thermodynamic units

    Science.gov (United States)

    Backhaus, Scott; Swift, Greg

    2013-06-25

    The present invention includes a thermoacoustic assembly and method for improved efficiency. The assembly has a first stage Stirling thermal unit comprising a main ambient heat exchanger, a regenerator and at least one additional heat exchanger. The first stage Stirling thermal unit is serially coupled to a first end of a quarter wavelength long coupling tube. A second stage Stirling thermal unit comprising a main ambient heat exchanger, a regenerator, and at least one additional heat exchanger, is serially coupled to a second end of the quarter wavelength long coupling tube.

  3. Generator coordinate method for triaxial quadrupole collective dynamics in strontium isotopes

    International Nuclear Information System (INIS)

    Bonche, P.; Dobaczewski, J.; Flocard, H.; Heenen, P.H.

    1991-01-01

    We discuss the algebraic structure of the generator coordinate method for triaxial quadrupole collective motion. The collective solutions are classified according to the representations of the permutation group of the intrinsic axes. Our method amounts to an approximate angular momentum projection. We apply it to a study of the spherical to deformed shape transition in light even strontium isotopes 78-88 Sr. We find that triaxial configurations play a significant role in explaining the structure of the transitional isotopes 80-82 Sr

  4. From Beale Number to Pole Placement Design of a Free Piston Stirling Engine

    Directory of Open Access Journals (Sweden)

    Zare Shahryar

    2017-12-01

    Full Text Available In this paper, pole placement-based design and analysis of a free piston Stirling engine (FPSE is presented and compared to the well-defined Beale number design technique. First, dynamic and thermodynamic equations governing the engine system are extracted. Then, linear dynamics of the free piston Stirling engine are studied using dynamic systems theory tools such as root locus. Accordingly, the effects of variations of design parameters such as mass of pistons, stiffness of springs, and frictional damping on the locations of dominant closed-loop poles are investigated. The design procedure is thus conducted to place the dominant poles of the dynamic system at desired locations on the s-plane so that the unstable dynamics, which is the required criterion for energy generation, is achieved. Next, the closed-loop poles are selected based on a desired frequency so that a periodical system is found. Consequently, the design parameters, including mass and spring stiffness for both power and displacer pistons, are obtained. Finally, the engine power is calculated through the proposed control-based analysis and the result is compared to those of the experimental work and the Beale number approach. The outcomes of this work clearly reveal the effectiveness of the control-based design technique of FPSEs compared to the well-known approaches such as Beale number.

  5. Economic performance of the SCE Stirling dish

    International Nuclear Information System (INIS)

    Stone, K.W.; Lopez, C.W.; McAlister, R.E.

    1993-01-01

    In 1982 McDonnell Douglas Aerospace Space System (MDA-SS) and United Stirling AB of Sweden formed a joint venture to develop and market a solar Stirling dish unit. Eight modules were built and extensively tested from 1984 to 1988. Power production and daily energy-conversion efficiency as determined by field testing have been characterized and modeled in a computer program. Included in this simulation are models of mirror soiling rate, wind spillage loss, mirror washing and other maintenance outage time, operation and maintenance (O and M) costs and other cost models. An economic model of a hybrid (combustion) receiver has been included in the simulation for illustrating the value of using solar energy when available and other fuels such as methane, natural gas, hydrogen, etc. when solar energy is not available or adequate. This paper describes the simulation and presents comparisons of the simulation to test data. The simulation also estimates both the O and M expenses and levelized energy costs for different production volumes

  6. Economic performance of the SCE Stirling dish

    International Nuclear Information System (INIS)

    Stone, K.W.; Lopez, C.W.; McAlister, R.E.

    1995-01-01

    In 1982 McDonnell Douglas Aerospace (MDA) and United Stirling AB (USAB) of Sweden formed a joint venture to develop and market a solar Stirling dish system. Eight modules were built and extensively tested from 1984 to 1988. Power production and daily energy-conversion efficiency as determined by field testing were characterized and modeled into a computer program. Included in this simulation are models of mirror soiling rate, wind spillage loss, mirror washing, and other maintenance outage time, operation and maintenance (O and M) costs, and equipment purchase cost. An economic model of a hybrid (combustion) receiver has been included in the simulation for illustrating the value of using solar energy when available and other fuels such as methane, natural gas, hydrogen, etc. when solar energy is not available or adequate. This paper describes the simulation and presents comparisons of the simulation to test data. The simulation also estimates both the O and M expenses and levelized energy costs for different production volumes

  7. On Generalizations of the Stirling Number Triangles

    Science.gov (United States)

    Lang, Wolfdieter

    2000-09-01

    Sequences of generalized Stirling numbers of both kinds are introduced. These sequences of triangles (i.e. infinite-dimensional lower triangular matrices) of numbers will be denoted by S2(k;n,m) and S1(k;n,m) with k in Z. The original Stirling number triangles of the second and first kind arise when k = 1. S2(2;n,m) is identical with the unsigned S1(2;n,m) triangle, called S1p(2;n,m), which also represents the triangle of signless Lah numbers. Certain associated number triangles, denoted by s2(k;n,m) and s1(k;n,m), are also defined. Both s2(2;n,m) and s1(2;n + 1, m + 1) form Pascal's triangle, and s2(-1,n,m) turns out to be Catalan's triangle. Generating functions are given for the columns of these triangles. Each S2(k) and S1(k) matrix is an example of a Jabotinsky matrix. Therefore the generating functions for the rows of these triangular arrays constitute exponential convolution polynomials. The sequences of the row sums of these triangles are also considered. These triangles are related to the problem of obtaining finite transformations from infinitesimal ones generated by x^k d/dx, for k in Z.

  8. Preliminary SP-100/Stirling heat exchanger designs

    International Nuclear Information System (INIS)

    Schmitz, P.; Tower, L.; Blue, B.; Dunn, P.

    1994-01-01

    Analytic modeling of several heat exchanger concepts to couple the SP-100 nuclear reactor lithium loop and the Space Stirling Power Convertor (SSPC) was performed. Four 25 kWe SSPC's are used to produce the required 100 kW of electrical power. This design work focused on the interface between a single SSPC and the primary lithium loop. Manifolding to separate and collect the four channel flow was not modeled. This work modeled two separate types of heat exchanger interfaces (conductive coupling and radiative coupling) to explore their relative advantages and disadvantages. The minimum mass design of the conductively coupled concepts was 18 kg or 0.73 kg/kWe for a single 25 kWe convertor. The minimum mass radiatively coupled concept was 41 kg or 1.64 kg/kWe. The direct conduction heat exchanger provides a lighter weight system because of its ability to operate the Stirling convertor evaporator at higher heat fluxes than those attainable by the radiatively coupled systems. Additionally the conductively coupled concepts had relatively small volumes and provide potentially simpler assembly. Their disadvantages were the tight tolerances and material joining problems associated with this refractory to superalloy interface. The advantages of the radiatively coupled designs were the minimal material interface problems

  9. Mathematical modeling of the static and dynamic behavior of the operational parameters of isotopic separation cascades composed of ultracentrifuges

    International Nuclear Information System (INIS)

    Portoghese, Celia Christiani Paschoa

    2002-01-01

    Several different mathematical models that make it possible to plan, design and follow the operation of uranium isotopic separation cascades using the gaseous ultracentrifugation process are presented, discussed and tested. Models to be used in the planning and conception phases use theoretical hypothesis, making it possible to calculate approximate values for the flow rate and isotopic composition of the cascade internal streams. Twelve theoretical models developed to perform this task are discussed and compared. The theoretical models that have greater applicability are identified. Models to be used for the complete dimensioning of a cascade, before its construction, called semi-empirical models, use experimental results obtained in ultracentrifuges individual testes combined with theoretical equations, allowing to calculate accurate values for the flow rate, pressure and isotopic composition of the cascade internal streams. Thirteen semi-empirical models developed to perform this task are presented, five of them are widely discussed and one of them is validated through comparison with experimental results. In order to follow the operation of a cascade, it is necessary to develop models to simulate its behavior in operational conditions other than the nominal, defined in the project. Three semi-empirical models to make this kind of simulation are presented and one of them is validated through comparison with experimental results. Finally, it is necessary to have tools that simulate the cascade behavior during transients. Two dynamic models developed to perform this task are presented and compared. The dynamic model capable to simulate results closer ti the real behaviour of a cascade during three different kinds of transient is identified, through comparison between simulated and experimental results. (author)

  10. Commissioning and Performance Analysis of WhisperGen Stirling Engine

    Science.gov (United States)

    Pradip, Prashant Kaliram

    Stirling engine based cogeneration systems have potential to reduce energy consumption and greenhouse gas emission, due to their high cogeneration efficiency and emission control due to steady external combustion. To date, most studies on this unit have focused on performance based on both experimentation and computer models, and lack experimental data for diversified operating ranges. This thesis starts with the commissioning of a WhisperGen Stirling engine with components and instrumentation to evaluate power and thermal performance of the system. Next, a parametric study on primary engine variables, including air, diesel, and coolant flowrate and temperature were carried out to further understand their effect on engine power and efficiency. Then, this trend was validated with the thermodynamic model developed for the energy analysis of a Stirling cycle. Finally, the energy balance of the Stirling engine was compared without and with heat recovery from the engine block and the combustion chamber exhaust.

  11. 40 kW Stirling Engine for Solid Fuel

    DEFF Research Database (Denmark)

    Carlsen, Henrik; Trærup, Jens

    1996-01-01

    The external combustion in a Stirling engine makes it very attractive for utilisation of solid fuels in decentralised combined heat and power (CHP) plants. Only a few projects have concentrated on the development of Stirling engines specifically for biomass. In this project, a Stirling engine has...... been designed primarily for utilisation of wood chips. Maximum shaft power is 40 kW corresponding to an electric output of 36 kW. Biomass needs more space in the combustion chamber compared to gas and liquid fuels, and a large heat transfer area is necessary. The design of the new Stirling engine has...... been adapted to the special demands of combustion of wood chips, resulting in a large engine compared to engines for gas or liquid fuels. The engine has four-cylinders arranged in a square. The design is made as a hermetic unit, where the alternator is built into the pressurised crankcase so...

  12. Stirling engine alternatives for the terrestrial solar application

    Science.gov (United States)

    Stearns, J.

    1985-01-01

    The first phase of the present study of Stirling engine alternatives for solar thermal-electric generation has been completed. Development risk levels are considered to be high for all engines evaluated. Free-piston type and Ringbom-type Stirling engine-alternators are not yet developed for the 25 to 50-kW electrical power range, although smaller machines have demonstrated the inherent robustness of the machines. Kinematic-type Stirling engines are presently achieving a 3500 hr lifetime or longer on critical components, and lifetime must still be further extended for the solar application. Operational and technical characteristics of all types of Stirling engines have been reviewed with engine developers. Technical work of merit in progress in each engine development organization should be recognized and supported in an appropriate manner.

  13. Optimal design of Stirling heat engine using an advanced ...

    Indian Academy of Sciences (India)

    R V Rao

    The comparisons of the proposed algorithm are made with those obtained by using the decision-making methods like linear ... cooling water and had improved the thermal efficiency of ... integrated system of a free-piston Stirling engine and an.

  14. Thermal Model Predictions of Advanced Stirling Radioisotope Generator Performance

    Science.gov (United States)

    Wang, Xiao-Yen J.; Fabanich, William Anthony; Schmitz, Paul C.

    2014-01-01

    This presentation describes the capabilities of three-dimensional thermal power model of advanced stirling radioisotope generator (ASRG). The performance of the ASRG is presented for different scenario, such as Venus flyby with or without the auxiliary cooling system.

  15. Development of Electronic Load Controllers for Free-Piston Stirling Convertors Aided by Stirling Simulation Model

    Science.gov (United States)

    Regan, Timothy F.

    2004-01-01

    The free-piston Stirling convertor end-to-end modeling effort at the NASA Glenn Research Center has produced a software-based test bed in which free-piston Stirling convertors can be simulated and evaluated. The simulation model includes all the components of the convertor: the Stirling cycle engine, heat source, linear alternator, controller, and load. So far, it has been used in evaluating the performance of electronic controller designs. Three different controller design concepts were simulated using the model: 1) Controllers with parasitic direct current loading. 2) Controllers with parasitic alternating current loading. 3) Controllers that maintain a reference current. The free-piston Stirling convertor is an electromechanical device that operates at resonance. It is the function of the electronic load controller to ensure that the electrical load seen by the machine is always great enough to keep the amplitude of the piston and alternator oscillation at the rated value. This is done by regulating the load on the output bus. The controller monitors the instantaneous voltage, regulating it by switching loads called parasitic loads onto the bus whenever the bus voltage is too high and removing them whenever the voltage is too low. In the first type of controller, the monitor-ing and switching are done on the direct-current (dc) bus. In the second type, the alternating current bus is used. The model allows designers to test a controller concept before investing time in hardware. The simulation code used to develop the model also offers detailed models of digital and analog electronic components so that the resulting designs are realistic enough to translate directly into hardware circuits.

  16. A comparative reliability analysis of free-piston Stirling machines

    Science.gov (United States)

    Schreiber, Jeffrey G.

    2001-02-01

    A free-piston Stirling power convertor is being developed for use in an advanced radioisotope power system to provide electric power for NASA deep space missions. These missions are typically long lived, lasting for up to 14 years. The Department of Energy (DOE) is responsible for providing the radioisotope power system for the NASA missions, and has managed the development of the free-piston power convertor for this application. The NASA Glenn Research Center has been involved in the development of Stirling power conversion technology for over 25 years and is currently providing support to DOE. Due to the nature of the potential missions, long life and high reliability are important features for the power system. Substantial resources have been spent on the development of long life Stirling cryocoolers for space applications. As a very general statement, free-piston Stirling power convertors have many features in common with free-piston Stirling cryocoolers, however there are also significant differences. For example, designs exist for both power convertors and cryocoolers that use the flexure bearing support system to provide noncontacting operation of the close-clearance moving parts. This technology and the operating experience derived from one application may be readily applied to the other application. This similarity does not pertain in the case of outgassing and contamination. In the cryocooler, the contaminants normally condense in the critical heat exchangers and foul the performance. In the Stirling power convertor just the opposite is true as contaminants condense on non-critical surfaces. A methodology was recently published that provides a relative comparison of reliability, and is applicable to systems. The methodology has been applied to compare the reliability of a Stirling cryocooler relative to that of a free-piston Stirling power convertor. The reliability analysis indicates that the power convertor should be able to have superior reliability

  17. White Paper on Dish Stirling Technology: Path Toward Commercial Deployment

    Energy Technology Data Exchange (ETDEWEB)

    Andraka, Charles E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Power Dept.; Stechel, Ellen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Power Dept.; Becker, Peter [Stirling Energy Systems, Scottsdale, AZ (United States); Messick, Brian [Stirling Energy Systems, Scottsdale, AZ (United States)

    2016-07-01

    Dish Stirling energy systems have been developed for distributed and large-scale utility deployment. This report summarizes the state of the technology in a joint project between Stirling Energy Systems, Sandia National Laboratories, and the Department of Energy in 2011. It then lays out a feasible path to large scale deployment, including development needs and anticipated cost reduction paths that will make a viable deployment product.

  18. Normal ordering problem and the extensions of the Stirling grammar

    Science.gov (United States)

    Ma, S.-M.; Mansour, T.; Schork, M.

    2014-04-01

    The purpose of this paper is to investigate the connection between context-free grammars and normal ordered problem, and then to explore various extensions of the Stirling grammar. We present grammatical characterizations of several well known combinatorial sequences, including the generalized Stirling numbers of the second kind related to the normal ordered problem and the r-Dowling polynomials. Also, possible avenues for future research are described.

  19. Advanced Stirling Convertor (ASC-E2) Characterization Testing

    Science.gov (United States)

    Williams, Zachary D.; Oriti, Salvatore M.

    2012-01-01

    Testing has been conducted on Advanced Stirling Convertors (ASCs)-E2 at NASA Glenn Research Center in support of the Advanced Stirling Radioisotope Generator (ASRG) project. This testing has been conducted to understand sensitivities of convertor parameters due to environmental and operational changes during operation of the ASRG in missions to space. This paper summarizes test results and explains the operation of the ASRG during space missions

  20. Sodium Variable Conductance Heat Pipe for Radioisotope Stirling Systems

    Science.gov (United States)

    Tarau, Calin; Anderson, William G.; Walker, Kara

    2009-01-01

    In a Stirling radioisotope system, heat must continually be removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the converter stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, and also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) has been designed to allow multiple stops and restarts of the Stirling convertor in an Advanced Stirling Radioisotope Generator (ASRG). When the Stirling convertor is turned off, the VCHP will activate when the temperatures rises 30 C above the setpoint temperature. A prototype VCHP with sodium as the working fluid was fabricated and tested in both gravity aided and against gravity conditions for a nominal heater head temperature of 790 C. The results show very good agreement with the predictions and validate the model. The gas front was located at the exit of the reservoir when heater head temperature was 790 C while cooling was ON, simulating an operating Advanced Stirling Converter (ASC). When cooling stopped, the temperature increased by 30 C, allowing the gas front to move past the radiator, which transferred the heat to the case. After resuming the cooling flow, the front returned at the initial location turning OFF the VCHP. The against gravity working conditions showed a colder reservoir and faster transients.

  1. New 5 Kilowatt Free-piston Stirling Space Convertor Developments

    Science.gov (United States)

    Brandhorst, Henry W., Jr.; Chapman, Peter A., Jr.

    2007-01-01

    The NASA Vision for Exploration of the moon may someday require a nuclear reactor coupled with a free-piston Stirling convertor at a power level of 30-40 kW. In the 1990s, Mechanical Technology Inc. s Stirling Engine Systems Division (some of whose Stirling personnel are now at Foster-Miller, Inc.) developed a 25 kW free piston Stirling Space Power Demonstrator Engine under the SP-100 program. This system consisted of two 12.5 kW engines connected at their hot ends and mounted in tandem to cancel vibration. Recently, NASA and DoE have been developing dual 55 W and 80 W Stirling convertor systems for potential use with radioisotope heat sources. Total test times of all convertors in this effort exceed 120,000 hours. Recently, NASA began a new project with Auburn University to develop a 5 kW, single convertor for potential use in a lunar surface reactor power system. Goals of this development program include a specific power in excess of 140 W/kg at the convertor level, lifetime in excess of five years and a control system that will safely manage the convertors in case of an emergency. Auburn University awarded a subcontract to Foster-Miller, Inc. to undertake development of the 5 kW Stirling Convertor Assembly. The characteristics of the design along with progress in developing the system will be described.

  2. Input of environmental isotopes in the study of the recharge and the flow dynamic of aquifers

    International Nuclear Information System (INIS)

    Aranyossy, J.F.; Njitchoua, R.; Zuppi, G.M.

    1998-01-01

    Several examples of hydrogeological studies have been selected in order to illustrate the input of environmental isotopic techniques in the general knowledge of aquifer systems: evaluation of the present aquifer recharge (Mali, Senegal, Italy, North-Cameroon, North-Sahara, Niger); evidence of the recharge variation with time (Niger, Italy, Vietnam); evaluation of the aquifer characteristics and hydraulic conditions (Chad, Niger). Most of these studies were carried out in collaboration with Professor Jean-Charles Fontes. (author)

  3. Application of Isotope Techniques for Assessing Nutrient Dynamics in River Basins

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-05-15

    Nutrients are necessary for the growth and survival of animals, plants and other organisms. However, industrial, agricultural and urban development has dramatically increased nutrient levels in river systems, including nitrogen and phosphorus containing substances, degrading water quality, causing acidification and eutrophication and affecting aquatic ecosystems. Nutrient assessment and management in river systems has been an important part of water resource management for the past few decades, but the provision of appropriate and effective nutrient assessment and management continues to be a challenge for water resource managers and policy makers. Difficulties in assessment and management are due in part to the fact that nutrients in rivers may originate from a variety of sources, take numerous pathways and transform into other substances. This publication presents the application of isotope techniques as a powerful tool for evaluating the sources, pathways, transformation, and fate of nutrients in river systems, focusing on nitrogen, phosphorus and carbon containing substances. Eleven researchers using various isotope techniques for different aspects of nutrient studies and two IAEA officers met in a technical meeting and discussed a publication that could assist water resource managers in dealing with nutrient assessment and management issues in river systems. These researchers also recognized the need for careful consideration in selecting appropriate isotope techniques in view of not only technical, but also financial, human resources and logistical capabilities, among others. These contributors are listed as major authors in the later pages of this document. This publication aims at serving water resource managers as a guidebook on the application of isotope techniques in nutrient assessment and management, but it is also expected to be of practical aid for other interested and concerned individuals and organization.

  4. Application of Isotope Techniques for Assessing Nutrient Dynamics in River Basins

    International Nuclear Information System (INIS)

    2013-05-01

    Nutrients are necessary for the growth and survival of animals, plants and other organisms. However, industrial, agricultural and urban development has dramatically increased nutrient levels in river systems, including nitrogen and phosphorus containing substances, degrading water quality, causing acidification and eutrophication and affecting aquatic ecosystems. Nutrient assessment and management in river systems has been an important part of water resource management for the past few decades, but the provision of appropriate and effective nutrient assessment and management continues to be a challenge for water resource managers and policy makers. Difficulties in assessment and management are due in part to the fact that nutrients in rivers may originate from a variety of sources, take numerous pathways and transform into other substances. This publication presents the application of isotope techniques as a powerful tool for evaluating the sources, pathways, transformation, and fate of nutrients in river systems, focusing on nitrogen, phosphorus and carbon containing substances. Eleven researchers using various isotope techniques for different aspects of nutrient studies and two IAEA officers met in a technical meeting and discussed a publication that could assist water resource managers in dealing with nutrient assessment and management issues in river systems. These researchers also recognized the need for careful consideration in selecting appropriate isotope techniques in view of not only technical, but also financial, human resources and logistical capabilities, among others. These contributors are listed as major authors in the later pages of this document. This publication aims at serving water resource managers as a guidebook on the application of isotope techniques in nutrient assessment and management, but it is also expected to be of practical aid for other interested and concerned individuals and organization.

  5. Quantum Dynamics Study of the Isotopic Effect on Capture Reactions: HD, D2 + CH3

    Science.gov (United States)

    Wang, Dunyou; Kwak, Dochan (Technical Monitor)

    2002-01-01

    Time-dependent wave-packet-propagation calculations are reported for the isotopic reactions, HD + CH3 and D2 + CH3, in six degrees of freedom and for zero total angular momentum. Initial state selected reaction probabilities for different initial rotational-vibrational states are presented in this study. This study shows that excitations of the HD(D2) enhances the reactivities; whereas the excitations of the CH3 umbrella mode have the opposite effects. This is consistent with the reaction of H2 + CH3. The comparison of these three isotopic reactions also shows the isotopic effects in the initial-state-selected reaction probabilities. The cumulative reaction probabilities (CRP) are obtained by summing over initial-state-selected reaction probabilities. The energy-shift approximation to account for the contribution of degrees of freedom missing in the six dimensionality calculation is employed to obtain approximate full-dimensional CRPs. The rate constant comparison shows H2 + CH3 reaction has the biggest reactivity, then HD + CH3, and D2 + CH3 has the smallest.

  6. Dynamics of metal-humate complexation equilibria as revealed by isotope exchange studies - a matter of concentration and time

    Science.gov (United States)

    Lippold, Holger; Eidner, Sascha; Kumke, Michael U.; Lippmann-Pipke, Johanna

    2017-01-01

    Complexation with dissolved humic matter can be crucial in controlling the mobility of toxic or radioactive contaminant metals. For speciation and transport modelling, a dynamic equilibrium process is commonly assumed, where association and dissociation run permanently. This is, however, questionable in view of reported observations of a growing resistance to dissociation over time. In this study, the isotope exchange principle was employed to gain direct insight into the dynamics of the complexation equilibrium, including kinetic inertisation phenomena. Terbium(III), an analogue of trivalent actinides, was used as a representative of higher-valent metals. Isotherms of binding to (flocculated) humic acid, determined by means of 160Tb as a radiotracer, were found to be identical regardless of whether the radioisotope was introduced together with the bulk of stable 159Tb or subsequently after pre-equilibration for up to 3 months. Consequently, there is a permanent exchange of free and humic-bound Tb since all available binding sites are occupied in the plateau region of the isotherm. The existence of a dynamic equilibrium was thus evidenced. There was no indication of an inertisation under these experimental conditions. If the small amount of 160Tb was introduced prior to saturation with 159Tb, the expected partial desorption of 160Tb occurred at much lower rates than observed for the equilibration process in the reverse procedure. In addition, the rates decreased with time of pre-equilibration. Inertisation phenomena are thus confined to the stronger sites of humic molecules (occupied at low metal concentrations). Analysing the time-dependent course of isotope exchange according to first-order kinetics indicated that up to 3 years are needed to attain equilibrium. Since, however, metal-humic interaction remains reversible, exchange of metals between humic carriers and mineral surfaces cannot be neglected on the long time scale to be considered in predictive

  7. Food-web dynamics and isotopic niches in deep-sea communities residing in a submarine canyon and on the adjacent open slopes

    Science.gov (United States)

    Demopoulos, Amanda W.J.; McClain-Counts, Jennifer; Ross, Steve W.; Brooke, Sandra; Mienis, Furu

    2017-01-01

    Examination of food webs and trophic niches provide insights into organisms' functional ecology, yet few studies have examined trophodynamics within submarine canyons, where the interaction of canyon morphology and oceanography influences habitat provision and food deposition. Using stable isotope analysis and Bayesian ellipses, we documented deep-sea food-web structure and trophic niches in Baltimore Canyon and the adjacent open slopes in the US Mid-Atlantic Region. Results revealed isotopically diverse feeding groups, comprising approximately 5 trophic levels. Regression analysis indicated that consumer isotope data are structured by habitat (canyon vs. slope), feeding group, and depth. Benthic feeders were enriched in 13C and 15N relative to suspension feeders, consistent with consuming older, more refractory organic matter. In contrast, canyon suspension feeders had the largest and more distinct isotopic niche, indicating they consume an isotopically discrete food source, possibly fresher organic material. The wider isotopic niche observed for canyon consumers indicated the presence of feeding specialists and generalists. High dispersion in δ13C values for canyon consumers suggests that the isotopic composition of particulate organic matter changes, which is linked to depositional dynamics, resulting in discrete zones of organic matter accumulation or resuspension. Heterogeneity in habitat and food availability likely enhances trophic diversity in canyons. Given their abundance in the world's oceans, our results from Baltimore Canyon suggest that submarine canyons may represent important havens for trophic diversity.

  8. Micro-cogeneration units based on Stirling engine for heating and their real operation

    Science.gov (United States)

    Čierny, Jaroslav; Patsch, Marek

    2014-08-01

    This article was deal with micro-cogeneration units based on Stirling engine. We watched problematic of real working Stirling engine. The article also contain hookup of unit constructed at University of Zilina.

  9. Feasibility Demonstration of a Multi-Cylinder Stirling Convertor with a Duplex Linear Alternator, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Stirling Technology Company (STC) proposes to integrate an existing Multi-Cylinder Free-Piston Stirling Engine (MPFPSE) with innovative compact linear alternators....

  10. Mathematical model of the Amazon Stirling engine

    Energy Technology Data Exchange (ETDEWEB)

    Vidal Medina, Juan Ricardo [Universidad Autonoma de Occidente (Colombia)], e-mail: jrvidal@uao.edu.co; Cobasa, Vladimir Melian; Silva, Electo [Universidade Federal de Itajuba, MG (Brazil)], e-mail: vlad@unifei.edu.br

    2010-07-01

    The Excellency Group in Thermoelectric and Distributed Generation (NEST, for its acronym in Portuguese) at the Federal University of Itajuba, has designed a Stirling engine prototype to provide electricity to isolated regions of Brazil. The engine was designed to operate with residual biomass from timber process. This paper presents mathematical models of heat exchangers (hot, cold and regenerator) integrated into second order adiabatic models. The general model takes into account the pressure drop losses, hysteresis and internal losses. The results of power output, engine efficiency, optimal velocity of the exhaust gases and the influence of dead volume in engine efficiency are presented in this paper. The objective of this modeling is to propose improvements to the manufactured engine design. (author)

  11. Stirling engine control mechanism and method

    Science.gov (United States)

    Dineen, John J.

    1983-01-01

    A reciprocating-to-rotating motion conversion and power control device for a Stirling engine includes a hub mounted on an offset portion of the output shaft for rotation relative to the shaft and for sliding motion therealong which causes the hub to tilt relative to the axis of rotation of the shaft. This changes the angle of inclination of the hub relative to the shaft axis and changes the axial stroke of a set of arms connected to the hub and nutating therewith. A hydraulic actuating mechanism is connected to the hub for moving its axial position along the shaft. A balancing wheel is linked to the hub and changes its angle of inclination as the angle of inclination of the hub changes to maintain the mechanism in perfect balance throughout its range of motion.

  12. Solar Stirling for deep space applications

    International Nuclear Information System (INIS)

    Mason, Lee S.

    2000-01-01

    A study was performed to quantify the performance of solar thermal power systems for deep space planetary missions. The study incorporated projected advances in solar concentrator and energy conversion technologies. These technologies included inflatable structures, lightweight primary concentrators, high efficiency secondary concentrators, and high efficiency Stirling convertors. Analyses were performed to determine the mass and deployed area of multihundred watt solar thermal power systems for missions out to 40 astronomical units. Emphasis was given to system optimization, parametric sensitivity analyses, and concentrator configuration comparisons. The results indicated that solar thermal power systems are a competitive alternative to radioisotope systems out to 10 astronomical units without the cost or safety implications associated with nuclear sources

  13. Creep rupture behavior of Stirling engine materials

    Science.gov (United States)

    Titran, R. H.; Scheuerman, C. M.; Stephens, J. R.

    1985-01-01

    The automotive Stirling engine, being investigated jointly by the Department of Energy and NASA Lewis as an alternate to the internal combustion engine, uses high-pressure hydrogen as the working fluid. The long-term effects of hydrogen on the high temperature strength properties of materials is relatively unknown. This is especially true for the newly developed low-cost iron base alloy NASAUT 4G-A1. This iron-base alloy when tested in air has creep-rupture strengths in the directionally solidified condition comparable to the cobalt base alloy HS-31. The equiaxed (investment cast) NASAUT 4G-A1 has superior creep-rupture to the equiaxed iron-base alloy XF-818 both in air and 15 MPa hydrogen.

  14. Cermet coatings for solar Stirling space power

    International Nuclear Information System (INIS)

    Jaworske, Donald A.; Raack, Taylor

    2004-01-01

    Cermet coatings, molecular mixtures of metal and ceramic, are being considered for the heat inlet surface of a solar Stirling space power convertor. The role of the cermet coating is to absorb as much of the incident solar energy as possible. The ability to mix metal and ceramic at the atomic level offers the opportunity to tailor the composition and the solar absorptance of these coatings. Several candidate cermet coatings were created and their solar absorptance was characterized as-manufactured and after exposure to elevated temperatures. Coating composition was purposely varied through the thickness of the coating. As a consequence of changing composition, islands of metal are thought to form in the ceramic matrix. Computer modeling indicated that diffusion of the metal atoms played an important role in island formation while the ceramic was important in locking the islands in place. Much of the solar spectrum is absorbed as it passes through this labyrinth

  15. Real-time isotope monitoring network at the Biosphere 2 Landscape Evolution Observatory resolves meter-to-catchment scale flow dynamics

    Science.gov (United States)

    Volkmann, T. H. M.; Van Haren, J. L. M.; Kim, M.; Harman, C. J.; Pangle, L.; Meredith, L. K.; Troch, P. A.

    2017-12-01

    Stable isotope analysis is a powerful tool for tracking flow pathways, residence times, and the partitioning of water resources through catchments. However, the capacity of stable isotopes to characterize catchment hydrological dynamics has not been fully exploited as commonly used methodologies constrain the frequency and extent at which isotopic data is available across hydrologically-relevant compartments (e.g. soil, plants, atmosphere, streams). Here, building upon significant recent developments in laser spectroscopy and sampling techniques, we present a fully automated monitoring network for tracing water isotopes through the three model catchments of the Landscape Evolution Observatory (LEO) at the Biosphere 2, University of Arizona. The network implements state-of-the-art techniques for monitoring in great spatiotemporal detail the stable isotope composition of water in the subsurface soil, the discharge outflow, and the atmosphere above the bare soil surface of each of the 330-m2 catchments. The extensive valving and probing systems facilitate repeated isotope measurements from a total of more than five-hundred locations across the LEO domain, complementing an already dense array of hydrometric and other sensors installed on, within, and above each catchment. The isotope monitoring network is operational and was leveraged during several months of experimentation with deuterium-labelled rain pulse applications. Data obtained during the experiments demonstrate the capacity of the monitoring network to resolve sub-meter to whole-catchment scale flow and transport dynamics in continuous time. Over the years to come, the isotope monitoring network is expected to serve as an essential tool for collaborative interdisciplinary Earth science at LEO, allowing us to disentangle changes in hydrological behavior as the model catchments evolve in time through weathering and colonization by plant communities.

  16. Alkali Metal Backup Cooling for Stirling Systems - Experimental Results

    Science.gov (United States)

    Schwendeman, Carl; Tarau, Calin; Anderson, William G.; Cornell, Peggy A.

    2013-01-01

    In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor. In a previous NASA SBIR Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for Stirling RPS. The operation of these VCHPs was demonstrated using Stirling heater head simulators and GPHS simulators. In the most recent effort, a sodium VCHP with a stainless steel envelope was designed, fabricated and tested at NASA Glenn Research Center (GRC) with a Stirling convertor for two concepts; one for the Advanced Stirling Radioisotope Generator (ASRG) back up cooling system and one for the Long-lived Venus Lander thermal management system. The VCHP is designed to activate and remove heat from the stopped convertor at a 19 degC temperature increase from the nominal vapor temperature. The 19 degC temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the Multi-Layer Insulation (MLI). In addition, the same backup cooling system can be applied to the Stirling convertor used for the refrigeration system of the Long-lived Venus Lander. The VCHP will allow the refrigeration system to: 1) rest during transit at a lower temperature than nominal; 2) pre-cool the modules to an even lower temperature before the entry in Venus atmosphere; 3) work at nominal temperature on Venus surface; 4) briefly stop multiple times on the Venus surface to allow scientific measurements. This paper presents the experimental

  17. Qualitative comparison of duplex Stirling and absorption refrigerators in domestic applications

    Energy Technology Data Exchange (ETDEWEB)

    Shao, H. [Global Cooling BV, Zutphen (Netherlands)

    2000-07-01

    A qualitative comparison has been carried out between the duplex Stirling and the absorption refrigerator for domestic applications. The duplex Stirling has many advantages over the absorption refrigerator on efficiency, modulation, suitability, operating costs, pollution reduction. Based on the state of the art of free-piston gas-bearing and linear-motor Stirling engines and coolers, it appears technically and economically feasible to develop the duplex Stirling to compete with the absorption refrigerator for heat-driven domestic refrigeration. (orig.)

  18. Dynamic changes of carbon isotope apparent fractionation factor to describe transition to syntrophic acetate oxidation during cellulose and acetate methanization.

    Science.gov (United States)

    Vavilin, Vasily A; Rytov, Sergey V

    2017-05-01

    To identify predominant metabolic pathway for cellulose methanization new equations that take into account dynamics of 13C are added to the basic model of cellulose methanization. The correct stoichiometry of hydrolysis, acidogenesis, acetogenesis and methanogenesis steps including biomass is considered. Using experimental data by Laukenmann et al. [Identification of methanogenic pathway in anaerobic digesters using stable carbon isotopes. Eng. Life Sci. 2010;10:1-6], who reported about the importance of ace`tate oxidation during mesophilic cellulose methanization, the model confirmed that, at high biomass concentration of acetate oxidizers, the carbon isotope fractionation factor amounts to about 1.085. The same model, suggested firstly for cellulose degradation, was used to describe, secondly, changes in, and in methane and carbon dioxide during mesophylic acetate methanization measured by Grossin-Debattista [Fractionnements isotopiques (13C/12C) engendres par la methanogenese: apports pour la comprehension des processus de biodegradation lors de la digestion anaerobie [doctoral thesis]. 2011. Bordeaux: Universite Bordeaux-1;2011. Available from: http://ori-oai.u-bordeaux1.fr/pdf/2011/GROSSIN-DEBATTISTA_JULIEN_2011.pdf . French].The model showed that under various ammonium concentrations, at dominating acetoclastic methanogenesis, the value decreases over time to a low level (1.016), while at dominating syntrophic acetate oxidation, coupled with hydrogenotrophic methanogenesis, slightly increases, reaching 1.060 at the end of incubation.

  19. Nitrogen balance and dynamics in corn under different soil fertility levels using “1“5N isotope tracer technique

    International Nuclear Information System (INIS)

    Rallos, R.V.; Rivera, F.G.; Samar, E.D.; Rojales, J.S.; Anida, A.H.

    2015-01-01

    Nitrogen (N) Fertilizer plays a vital role on the growth and development of any crop. The inefficient N fertilizer utilization contributes to poor crop productivity and environment pollution. This study used the 15N isotope tracer technique to understand the nitrogen balance and dynamics in corn grown during the wet and dry season for low, medium and high N soils in Northern Luzon. The experiments were laid out following the randomized complete block design (RCBD) potassium requirements were applied at optimum level on solid chemical analysis and fertilizer recommendation. The study was able to separate the source of N from applied fertilizer and from the soils, traced using 15N during the 30 days after planting (DAP), 60 DAP and at harvest. Result show that, more than half of N in the plant came directly from added fertilizer during the early stage, which decreased towards harvest period. Fertilizer N yield use efficiency showed negative relationship with the rate of N application and soil fertility levels. Of N fertilization in different soil fertility levels were also established using isotope tracer technique. (author)

  20. Trajectory Calculations for Bergman Cyclization Predict H/D Kinetic Isotope Effects Due to Nonstatistical Dynamics in the Product.

    Science.gov (United States)

    Doubleday, Charles; Boguslav, Mayla; Howell, Caronae; Korotkin, Scott D; Shaked, David

    2016-06-22

    An unusual H/D kinetic isotope effect (KIE) is described, in which isotopic selectivity arises primarily from nonstatistical dynamics in the product. In DFT-based quasiclassical trajectories of Bergman cyclization of (Z)-3-hexen-1,5-diyne (1) at 470 K, the new CC bond retains its energy, and 28% of nascent p-benzyne recrosses back to the enediyne on a vibrational time scale. The competing process of intramolecular vibrational redistribution (IVR) in p-benzyne is too slow to prevent this. Deuteration increases the rate of IVR, which decreases the fraction of recrossing and increases the yield of statistical (trapable) p-benzyne, 2. Trapable yields for three isotopomers of 2 range from 72% to 86%. The resulting KIEs for Bergman cyclization differ substantially from KIEs predicted by transition state theory, which suggests that IVR in this reaction can be studied by conventional KIEs. Leakage of vibrational zero point energy (ZPE) into the reaction coordinate was probed by trajectories in which initial ZPE in the CH/CD stretching modes was reduced by 25%. This did not change the predicted KIEs.

  1. Strontium isotopes provide clues for a process shift in base cation dynamics in young volcanic soils

    Science.gov (United States)

    Bingham, N.; Jackson, M. G.; Bookhagen, B.; Maher, K.; Chadwick, O.

    2015-12-01

    Despite advances in soil development theory based on studies of old soils or over long timescales, little is known about soil thresholds (dramatic changes in soil properties associated with only small shifts in external forcing factors) that might be expressed in young soils (less than 10 kyr). Therefore, we seek to understand infant soil development in a tropical environment through the sourcing of plant available base cations by measuring the strontium (Sr) isotopic composition of the soil exchange complex. Our sampling strategy spans soils in three different precipitation ranges (950-1060 mm, 1180-1210 mm, and 1450-1500) and an array of soil ages from 500 to 7500 years in the Kona region on the island of Hawaii. In Hawaiian soils, 87Sr/86Sr values are determined by a mixture of three components: a mantle-derived component from the lava (0.7034), a rainfall component (0.7093) and a component from continental dust (0.720). Elevation-controlled leaching intensity in the wettest localities produces a decline in the concentration of base cations supplied by basalt and a dilute resupply by rainfall. In the driest sites, where leaching intensity is dramatically reduced, there is a buildup of rainfall-derived extractable Sr in the soil over time. Slow rock weathering rates produce a small rock-derived cation input to the soil. Thus, Sr isotope signatures reflect both the input of rainfall-derived cations and rock-derived cations with values that fall between rainfall and basaltic signatures. Soils in the intermediate precipitation range have Sr isotopic signatures consistent with both the wet and dry trends; suggesting that they lie close to the critical precipitation amount that marks a shift between these two processes. For the Kona region, this transition seems to occur at 1200 mm /yr. In contrast to the clear-cut differentiation in strontium isotopes with precipitation shifts observed in older soils, patterns on these young soils in Kona are complicated by low soil

  2. Overview of NASA Lewis Research Center free-piston Stirling engine technology activities applicable to space power systems

    Science.gov (United States)

    Slaby, Jack G.

    1987-01-01

    A brief overview is presented of the development and technological activities of the free-piston Stirling engine. The engine started as a small scale fractional horsepower engine which demonstrated basic engine operating principles and the advantages of being hermetically sealed, highly efficient, and simple. It eventually developed into the free piston Stirling engine driven heat pump, and then into the SP-100 Space Reactor Power Program from which came the Space Power Demonstrator Engine (SPDE). The SPDE successfully operated for over 300 hr and delivered 20 kW of PV power to an alternator plunger. The SPDE demonstrated that a dynamic power conversion system can, with proper design, be balanced; and the engine performed well with externally pumped hydrostatic gas bearings.

  3. Estimates of water source contributions in a dynamic urban water supply system inferred via a Bayesian stable isotope mixing model

    Science.gov (United States)

    Jameel, M. Y.; Brewer, S.; Fiorella, R.; Tipple, B. J.; Bowen, G. J.; Terry, S.

    2017-12-01

    Public water supply systems (PWSS) are complex distribution systems and critical infrastructure, making them vulnerable to physical disruption and contamination. Exploring the susceptibility of PWSS to such perturbations requires detailed knowledge of the supply system structure and operation. Although the physical structure of supply systems (i.e., pipeline connection) is usually well documented for developed cities, the actual flow patterns of water in these systems are typically unknown or estimated based on hydrodynamic models with limited observational validation. Here, we present a novel method for mapping the flow structure of water in a large, complex PWSS, building upon recent work highlighting the potential of stable isotopes of water (SIW) to document water management practices within complex PWSS. We sampled a major water distribution system of the Salt Lake Valley, Utah, measuring SIW of water sources, treatment facilities, and numerous sites within in the supply system. We then developed a hierarchical Bayesian (HB) isotope mixing model to quantify the proportion of water supplied by different sources at sites within the supply system. Known production volumes and spatial distance effects were used to define the prior probabilities for each source; however, we did not include other physical information about the supply system. Our results were in general agreement with those obtained by hydrodynamic models and provide quantitative estimates of contributions of different water sources to a given site along with robust estimates of uncertainty. Secondary properties of the supply system, such as regions of "static" and "dynamic" source (e.g., regions supplied dominantly by one source vs. those experiencing active mixing between multiple sources), can be inferred from the results. The isotope-based HB isotope mixing model offers a new investigative technique for analyzing PWSS and documenting aspects of supply system structure and operation that are

  4. Magma reservoir dynamics at Toba caldera, Indonesia, recorded by oxygen isotope zoning in quartz.

    Science.gov (United States)

    Budd, David A; Troll, Valentin R; Deegan, Frances M; Jolis, Ester M; Smith, Victoria C; Whitehouse, Martin J; Harris, Chris; Freda, Carmela; Hilton, David R; Halldórsson, Sæmundur A; Bindeman, Ilya N

    2017-01-25

    Quartz is a common phase in high-silica igneous rocks and is resistant to post-eruptive alteration, thus offering a reliable record of magmatic processes in silicic magma systems. Here we employ the 75 ka Toba super-eruption as a case study to show that quartz can resolve late-stage temporal changes in magmatic δ 18 O values. Overall, Toba quartz crystals exhibit comparatively high δ 18 O values, up to 10.2‰, due to magma residence within, and assimilation of, local granite basement. However, some 40% of the analysed quartz crystals display a decrease in δ 18 O values in outermost growth zones compared to their cores, with values as low as 6.7‰ (maximum ∆ core-rim  = 1.8‰). These lower values are consistent with the limited zircon record available for Toba, and the crystallisation history of Toba quartz traces an influx of a low-δ 18 O component into the magma reservoir just prior to eruption. Here we argue that this late-stage low-δ 18 O component is derived from hydrothermally-altered roof material. Our study demonstrates that quartz isotope stratigraphy can resolve magmatic events that may remain undetected by whole-rock or zircon isotope studies, and that assimilation of altered roof material may represent a viable eruption trigger in large Toba-style magmatic systems.

  5. Time-dependent view of an isotope effect in electron-nuclear nonequilibrium dynamics with applications to N2.

    Science.gov (United States)

    Ajay, Jayanth S; Komarova, Ksenia G; Remacle, Francoise; Levine, R D

    2018-05-21

    Isotopic fractionation in the photodissociation of N 2 could explain the considerable variation in the 14 N/ 15 N ratio in different regions of our galaxy. We previously proposed that such an isotope effect is due to coupling of photoexcited bound valence and Rydberg electronic states in the frequency range where there is strong state mixing. We here identify features of the role of the mass in the dynamics through a time-dependent quantum-mechanical simulation. The photoexcitation of N 2 is by an ultrashort pulse so that the process has a sharply defined origin in time and so that we can monitor the isolated molecule dynamics in time. An ultrafast pulse is necessarily broad in frequency and spans several excited electronic states. Each excited molecule is therefore not in a given electronic state but in a superposition state. A short time after excitation, there is a fairly sharp onset of a mass-dependent large population transfer when wave packets on two different electronic states in the same molecule overlap. This coherent overlap of the wave packets on different electronic states in the region of strong coupling allows an effective transfer of population that is very mass dependent. The extent of the transfer depends on the product of the populations on the two different electronic states and on their relative phase. It is as if two molecules collide but the process occurs within one molecule, a molecule that is simultaneously in both states. An analytical toy model recovers the (strong) mass and energy dependence.

  6. Silicon pool dynamics and biogenic silica export in the Southern Ocean inferred from Si-isotopes

    Directory of Open Access Journals (Sweden)

    F. Fripiat

    2011-09-01

    Full Text Available Silicon isotopic signatures (δ30Si of water column silicic acid (Si(OH4 were measured in the Southern Ocean, along a meridional transect from South Africa (Subtropical Zone down to 57° S (northern Weddell Gyre. This provides the first reported data of a summer transect across the whole Antarctic Circumpolar Current (ACC. δ30Si variations are large in the upper 1000 m, reflecting the effect of the silica pump superimposed upon meridional water transfer across the ACC: the transport of Antarctic surface waters northward by a net Ekman drift and their convergence and mixing with warmer upper-ocean Si-depleted waters to the north. Using Si isotopic signatures, we determine different mixing interfaces: the Antarctic Surface Water (AASW, the Antarctic Intermediate Water (AAIW, and thermoclines in the low latitude areas. The residual silicic acid concentrations of end-members control the δ30Si alteration of the mixing products and with the exception of AASW, all mixing interfaces have a highly Si-depleted mixed layer end-member. These processes deplete the silicic acid AASW concentration northward, across the different interfaces, without significantly changing the AASW δ30Si composition. By comparing our new results with a previous study in the Australian sector we show that during the circumpolar transport of the ACC eastward, the δ30Si composition of the silicic acid pools is getting slightly, but significantly lighter from the Atlantic to the Australian sectors. This results either from the dissolution of biogenic silica in the deeper layers and/or from an isopycnal mixing with the deep water masses in the different oceanic basins: North Atlantic Deep Water in the Atlantic, and Indian Ocean deep water in the Indo-Australian sector. This isotopic trend is further transmitted to the subsurface waters, representing mixing interfaces between the surface and deeper layers.

  7. Equivalent electrical network model approach applied to a double acting low temperature differential Stirling engine

    International Nuclear Information System (INIS)

    Formosa, Fabien; Badel, Adrien; Lottin, Jacques

    2014-01-01

    Highlights: • An equivalent electrical network modeling of Stirling engine is proposed. • This model is applied to a membrane low temperate double acting Stirling engine. • The operating conditions (self-startup and steady state behavior) are defined. • An experimental engine is presented and tested. • The model is validated against experimental results. - Abstract: This work presents a network model to simulate the periodic behavior of a double acting free piston type Stirling engine. Each component of the engine is considered independently and its equivalent electrical circuit derived. When assembled in a global electrical network, a global model of the engine is established. Its steady behavior can be obtained by the analysis of the transfer function for one phase from the piston to the expansion chamber. It is then possible to simulate the dynamic (steady state stroke and operation frequency) as well as the thermodynamic performances (output power and efficiency) for given mean pressure, heat source and heat sink temperatures. The motion amplitude especially can be determined by the spring-mass properties of the moving parts and the main nonlinear effects which are taken into account in the model. The thermodynamic features of the model have then been validated using the classical isothermal Schmidt analysis for a given stroke. A three-phase low temperature differential double acting free membrane architecture has been built and tested. The experimental results are compared with the model and a satisfactory agreement is obtained. The stroke and operating frequency are predicted with less than 2% error whereas the output power discrepancy is of about 30%. Finally, some optimization routes are suggested to improve the design and maximize the performances aiming at waste heat recovery applications

  8. A Stirling engine for use with lower quality fuels

    Science.gov (United States)

    Paul, Christopher J.

    There is increasing interest in using renewable fuels from biomass or alternative fuels such as municipal waste to reduce the need for fossil based fuels. Due to the lower heating values and higher levels of impurities, small scale electricity generation is more problematic. Currently, there are not many technologically mature options for small scale electricity generation using lower quality fuels. Even though there are few manufacturers of Stirling engines, the history of their development for two centuries offers significant guidance in developing a viable small scale generator set using lower quality fuels. The history, development, and modeling of Stirling engines were reviewed to identify possible model and engine configurations. A Stirling engine model based on the finite volume, ideal adiabatic model was developed. Flow dissipation losses are shown to need correcting as they increase significantly at low mean engine pressure and high engine speed. The complete engine including external components was developed. A simple yet effective method of evaluating the external heat transfer to the Stirling engine was created that can be used with any second order Stirling engine model. A derivative of the General Motors Ground Power Unit 3 was designed. By significantly increasing heater, cooler and regenerator size at the expense of increased dead volume, and adding a combustion gas recirculation, a generator set with good efficiency was designed.

  9. Insoluble Coatings for Stirling Engine Heat Pipe Condenser Surfaces

    Science.gov (United States)

    Dussinger, Peter M.; Lindemuth, James E.

    1997-01-01

    The principal objective of this Phase 2 SBIR program was to develop and demonstrate a practically insoluble coating for nickel-based superalloys for Stirling engine heat pipe applications. Specific technical objectives of the program were: (1) Determine the solubility corrosion rates for Nickel 200, Inconel 718, and Udimet 72OLI in a simulated Stirling engine heat pipe environment, (2) Develop coating processes and techniques for capillary groove and screen wick structures, (3) Evaluate the durability and solubility corrosion rates for capillary groove and screen wick structures coated with an insoluble coating in cylindrical heat pipes operating under Stirling engine conditions, and (4) Design and fabricate a coated full-scale, partial segment of the current Stirling engine heat pipe for the Stirling Space Power Convertor program. The work effort successfully demonstrated a two-step nickel aluminide coating process for groove wick structures and interior wall surfaces in contact with liquid metals; demonstrated a one-step nickel aluminide coating process for nickel screen wick structures; and developed and demonstrated a two-step aluminum-to-nickel aluminide coating process for nickel screen wick structures. In addition, the full-scale, partial segment was fabricated and the interior surfaces and wick structures were coated. The heat pipe was charged with sodium, processed, and scheduled to be life tested for up to ten years as a Phase 3 effort.

  10. Stirling based micro co-generation system for single households

    Energy Technology Data Exchange (ETDEWEB)

    Ribberink, J.S.; Zutt, J.G.M.; Rabou, L.P.L.M.; Beckers, G.J.J. [ECN Clean Fossil Fuels, Petten (Netherlands); Baijens, C.A.W.; Luttikholt, J.J.M. [ATAG Verwarming, Lichtenvoorde (Netherlands)

    2000-04-01

    This paper describes the progress made in the ENATEC development program for a free piston Stirling engine based micro co-generation system that serves the supply of up to 1 kW{sub e} and up to 24 kW heat for domestic heating and/or for hot tap water production for single households at overall system efficiencies of 96%. Experiments show that the free piston Stirling engines from Stirling Technology Company run very reliably and controllably, and that the efficiency targets for the 1 kW{sub e} micro co-generation system are feasible. A ceramic foam burner with good heat transfer characteristics and low NOx emissions was developed. A demonstration micro co-generation unit was built and successfully presented. A 1 kW{sub e} free piston Stirling engine for the European market was developed. High efficiencies at full load and at part load, low emissions, low noise, and minimum maintenance make the Stirling engine based micro co-generation system an attractive candidate for the next generation of domestic boilers in Europe. 5 refs.

  11. Effective multi-objective optimization of Stirling engine systems

    International Nuclear Information System (INIS)

    Punnathanam, Varun; Kotecha, Prakash

    2016-01-01

    Highlights: • Multi-objective optimization of three recent Stirling engine models. • Use of efficient crossover and mutation operators for real coded Genetic Algorithm. • Demonstrated supremacy of the strategy over the conventionally used algorithm. • Improvements of up to 29% in comparison to literature results. - Abstract: In this article we demonstrate the supremacy of the Non-dominated Sorting Genetic Algorithm-II with Simulated Binary Crossover and Polynomial Mutation operators for the multi-objective optimization of Stirling engine systems by providing three examples, viz., (i) finite time thermodynamic model, (ii) Stirling engine thermal model with associated irreversibility and (iii) polytropic finite speed based thermodynamics. The finite time thermodynamic model involves seven decision variables and consists of three objectives: output power, thermal efficiency and rate of entropy generation. In comparison to literature, it was observed that the used strategy provides a better Pareto front and leads to improvements of up to 29%. The performance is also evaluated on a Stirling engine thermal model which considers the associated irreversibility of the cycle and consists of three objectives involving eleven decision variables. The supremacy of the suggested strategy is also demonstrated on the experimentally validated polytropic finite speed thermodynamics based Stirling engine model for optimization involving two objectives and ten decision variables.

  12. Optimization of powered Stirling heat engine with finite speed thermodynamics

    International Nuclear Information System (INIS)

    Ahmadi, Mohammad H.; Ahmadi, Mohammad Ali; Pourfayaz, Fathollah; Bidi, Mokhtar; Hosseinzade, Hadi; Feidt, Michel

    2016-01-01

    Highlights: • Based on finite speed method and direct method, the optimal performance is investigated. • The effects of major parameters on the optimal performance are investigated. • The accuracy of the results was compared with previous works. - Abstract: Popular thermodynamic analyses including finite time thermodynamic analysis was lately developed based upon external irreversibilities while internal irreversibilities such as friction, pressure drop and entropy generation were not considered. The aforementioned disadvantage reduces the reliability of the finite time thermodynamic analysis in the design of an accurate Stirling engine model. Consequently, the finite time thermodynamic analysis could not sufficiently satisfy researchers for implementing in design and optimization issues. In this study, finite speed thermodynamic analysis was employed instead of finite time thermodynamic analysis for studying Stirling heat engine. The finite speed thermodynamic analysis approach is based on the first law of thermodynamics for a closed system with finite speed and the direct method. The effects of heat source temperature, regenerating effectiveness, volumetric ratio, piston stroke as well as rotational speed are included in the analysis. Moreover, maximum output power in optimal rotational speed was calculated while pressure losses in the Stirling engine were systematically considered. The result reveals the accuracy and the reliability of the finite speed thermodynamic method in thermodynamic analysis of Stirling heat engine. The outcomes can help researchers in the design of an appropriate and efficient Stirling engine.

  13. Selection of stirling engine parameter and modes of joint operation with the Topaz II

    International Nuclear Information System (INIS)

    Kirillov, E.Y.; Ogloblin, B.G.; Shalaev, A.I.

    1996-01-01

    In addition to a high-temperature thermionic conversion cycle, application of a low-temperature machine cycle, such as the Stirling engine, is being considered. To select the optimum mode for joint operation of the Topaz II system and Stirling engine, output electric parameters are obtained as a function of thermal power released in the TFE fuel cores. The hydraulic diagram used for joint operation of the Topaz II and the Stirling engine is considered. Requirements to hydraulic characteristics of the Stirling engine heat exchanges are formulated. Scope of necessary modifications to mount the Stirling Engine on the Topaz II is estimated. copyright 1996 American Institute of Physics

  14. The kinematic Stirling engine as an energy conversion subsystem for paraboloidal dish solar thermal plants

    Science.gov (United States)

    Bowyer, J. M.

    1984-01-01

    The potential of a suitably designed and economically manufactured Stirling engine as the energy conversion subsystem of a paraboloidal dish-Stirling solar thermal power module was estimated. Results obtained by elementary cycle analyses were shown to match quite well the performance characteristics of an advanced kinematic Stirling engine, the United Stirling P-40, as established by current prototypes of the engine and by a more sophisticated analytic model of its advanced derivative. In addition to performance, brief consideration was given to other Stirling engine criteria such as durability, reliability, and serviceability. Production costs were not considered here.

  15. Isotopic evaluations of dynamic and plant uptake of N in soil amended with 15N-labelled sewage sludge

    International Nuclear Information System (INIS)

    Kchaou, R.; Khelil, M. N.; Rejeb, S.; Gharbi, F.; Henchi, B.; Hernandez, T.; Destain, J. P.

    2010-01-01

    Field experiments were conducted to evaluate the use of a novel 15N isotope technique for comparing the dynamics of N derived from sewage sludge applied to sorghum to the dynamics of N derived from the commercial fertilizer, urea. The treatments included a control, sludge applied at three rates (3, 6 and 9 t/ha, or 113, 226 and 338 kg N/ha) and N-urea applied at three rates (150, 250 and 350 kg N/ha). Recovery of 15N -labelled sludge was similar for the different nitrogen rates applied , with a mean value of 27%. However, the recovery of 15N -urea decreased as the rate of N application increased (from 38% to 27%). Approximately 22% and 19% of the 15N from sludge and urea, respectively, remained in the 0-60 cm layer of soil, most of which was present in the 0-20 cm layer. Furthermore, losses of 15N -labelled fertilizer were not affected by the N fertilization source, and the greatest losses, which were measured in response to the highest N application rate, were 59%. (authors)

  16. Use of biomass as fuel for Stirling motors; Uso de biomassa como combustivel para acionamento de motores Stirling

    Energy Technology Data Exchange (ETDEWEB)

    Barros, Robledo Wakin; Aradas, Maria Eugenia Coria; Cobas, Vladmir Rafael Melian; Lora, Electo Eduardo Silva [Universidade Federal de Itajuba (UNIFEI), MG (Brazil). Inst. de Engenharia Mecanica. Nucleo de Estudos em Sistemas Termicos], e-mail: robledo@unifei.edu.br

    2004-07-01

    The search to increase the electrical generation, together with the need to decrease the pollution emission, has encouraged the alternative energy sources. Nowadays around the world there are a lot of alternative energy sources incentive programs. In Brazil have PROINFA - Alternative Energy Sources Incentive Program. An example of alternative energy sources is the use of biomass as combustible. In the electrical generation, the biomass can be used directly, having it's directly combustion, and transforming the thermal energy liberated in electrical energy, or can be transformed in gas or liquid, and after use technology as internal combustion engine and gas turbine to generate electricity with these combustibles. Few technologies can be used to generate electricity burning directly to the biomass. Among these technologies, have the Stirling engine. It is possible to use this engine because the Stirling engines are external combustion engines, and it has not contact between the work gas and the flue gas. In this way, the Stirling engine needs a heat source, independent of the combustible type that will be used, including solar source. In this work will be present this technology, the different kinds of Stirling engines according to their configuration, moreover will be present the ST 05 G Stirling engine, which is a 500 W engine, acquired by University Federal of Itajuba. Also are present the tests results of this engine, and the installation to work with wood waste as combustible. (author)

  17. Improving Power Density of Free-Piston Stirling Engines

    Science.gov (United States)

    Briggs, Maxwell H.; Prahl, Joseph M.; Loparo, Kenneth A.

    2016-01-01

    Analyses and experiments demonstrate the potential benefits of optimizing piston and displacer motion in a free-piston Stirling Engine. Isothermal analysis shows the theoretical limits of power density improvement due to ideal motion in ideal Stirling engines. More realistic models based on nodal analysis show that ideal piston and displacer waveforms are not optimal, often producing less power than engines that use sinusoidal piston and displacer motion. Constrained optimization using nodal analysis predicts that Stirling engine power density can be increased by as much as 58 percent using optimized higher harmonic piston and displacer motion. An experiment is conducted in which an engine designed for sinusoidal motion is forced to operate with both second and third harmonics, resulting in a piston power increase of as much as 14 percent. Analytical predictions are compared to experimental data and show close agreement with indirect thermodynamic power calculations, but poor agreement with direct electrical power measurements.

  18. Integrated two-cylinder liquid piston Stirling engine

    Science.gov (United States)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin; Sulchek, Todd

    2014-10-01

    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.

  19. Integrated two-cylinder liquid piston Stirling engine

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin; Sulchek, Todd, E-mail: todd.sulchek@me.gatech.edu [George W. Woodruff School of Mechanical Engineering and Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2014-10-06

    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.

  20. Experimental study of the pressure characteristics in the Stirling refrigerator

    International Nuclear Information System (INIS)

    Hong, Yong Ju; Park, Seong Je; Kim, Hyo Bong; Koh, Deuk Yong

    2001-01-01

    The linear compressor have been widely used for pressure wave generation in the Stirling cryocooler and Stirling type pulse tube cryocooler for tactical purpose. The linear compressor has small and compact structure, and long life due to having non-contact sealing mechanism and the pressure drop through regenerator was ver important role in the motion of displacer in the expander of the Stirling cryocooler. In this study, the characteristic of the linear compressor and the pressure drop through regenerator in the expander was experimentally investigated. The results show resonance of the compressor is very important to get maximum performance and the gas spring force in the compression space of the compressor has effect on the characteristic of resonance and the results show the pressure drop through regenerator is very small than operating pressure change

  1. Micro power/heat cogeneration incorporating a stirling engine

    International Nuclear Information System (INIS)

    Luft, S.

    2003-01-01

    The Stirling-engine for CHP-purpose developed by SOLO is a trend-setting technology. It represents the most suspicious perspective apart from the fuel-cell technology in order to become suitable to the requirements of the future power supply in the focus of the sustainability and the decentralized energy supply. The charm of the Stirling technology is based on the external combustion: a so far not known variability with the primary energy choice as well as a life span substantially extending, wear-free operation are possible thereby. The external combustion reduces also the maintenance and the emissions in a measure not known with conventional engine technologies. The development steps are finished. The result is the world-wide first concept for the commercial, stationary application of decentralized micro-CHP on Stirling technology basis, which goes into series. (orig.) [de

  2. The 1-kW solar Stirling experiment

    Science.gov (United States)

    Giandomenico, A.

    1981-01-01

    The objective of this experiment was to demonstrate electrical power generation using a small free-piston Stirling engine and linear alternator in conjunction with a parabolic solar collector. A test bed collector, formerly used at the JPL Table Mountain Observatory, was renovated and used to obtain practical experience and to determine test receiver performance. The collector was mounted on a two-axis tracker, with a cold water calorimeter mounted on the collector to measure its efficiency, while a separate, independently tracking radiometer was used to measure solar insolation. The solar receiver was designed to absorb energy from the collector, then transfer the resulting thermal energy to the Stirling engine. Successful testing of receiver/collector assembly yielded valuable inputs for design of the Stirling engine heater head.

  3. Integrated two-cylinder liquid piston Stirling engine

    International Nuclear Information System (INIS)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin; Sulchek, Todd

    2014-01-01

    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.

  4. Improving Free-Piston Stirling Engine Power Density

    Science.gov (United States)

    Briggs, Maxwell H.

    2016-01-01

    Analyses and experiments demonstrate the potential benefits of optimizing piston and displacer motion in a free piston Stirling Engine. Isothermal analysis shows the theoretical limits of power density improvement due to ideal motion in ideal Stirling engines. More realistic models based on nodal analysis show that ideal piston and displacer waveforms are not optimal, often producing less power than engines that use sinusoidal piston and displacer motion. Constrained optimization using nodal analysis predicts that Stirling engine power density can be increased by as much as 58% using optimized higher harmonic piston and displacer motion. An experiment is conducted in which an engine designed for sinusoidal motion is forced to operate with both second and third harmonics, resulting in a maximum piston power increase of 14%. Analytical predictions are compared to experimental data showing close agreement with indirect thermodynamic power calculations, but poor agreement with direct electrical power measurements.

  5. Overview of NASA supported Stirling thermodynamic loss research

    International Nuclear Information System (INIS)

    Tew, R.C.; Geng, S.M.

    1994-01-01

    The National Aeronautics and Space Administration (NASA) is funding research to characterize Stirling machine thermodynamic losses. NASA's primary goal is to improve Stirling design codes to support engine development for space and terrestrial power. However, much of the fundamental data is applicable to Stirling cooler and heat pump applications. The research results are reviewed. Much has been learned about oscillating-flow hydrodynamics, including laminar/turbulent transition, and tabulated data has been documented for further analysis. Now, with a better understanding of the oscillator-flow field, it is time to begin measuring the effects of oscillating flow and oscillating pressure level on heat transfer in heat exchanger flow passages and in cylinders. This critical phase of the work is just beginning

  6. Cool down time optimization of the Stirling cooler

    Science.gov (United States)

    Xia, M.; Chen, X. P.; Y Li, H.; Gan, Z. H.

    2017-12-01

    The cooling power is one of the most important performances of a Stirling cooler. However, in some special fields, the cool down time is more important. It is a great challenge to improve the cool down time of the Stirling cooler. A new split Stirling linear cryogenic cooler SCI09H was designed in this study. A new structure of linear motor is used in the compressor, and the machine spring is used in the expander. In order to reduce the cool down time, the stainless-steel mesh of regenerator is optimized. The weight of the cooler is 1.1 kg, the cool down time to 80K is 2 minutes at 296K with a 250J thermal mass, the cooling power is 1.1W at 80K, and the input power is 50W.

  7. Large eight.cylinder Stirling engine for biofuels

    DEFF Research Database (Denmark)

    Carlsen, Henrik; Biedermann, F.; Bovin, Jonas Kabell

    2003-01-01

    A large Stirling engine with an electric power output of 70 kW has been developed for small-scale CHP using wood chips and other sorts of biomass as fuel. The development of the engine is based on the results from the development of a four-cylinder Stirling engine with a power output of 35 k...... in the hot end connecting the expansion space with the hot end of the regenerator through the heater panel. However, this has resulted in comparably large dead volumes and flow losses in the connections between the heater and the regenerator/expansion volume. For the new eight-cylinder engine the design...... of the connections between the heater and the regenerator/expansion volume have been improved considerably, reducing the flow losses and internal dead volume. Results from simulations indicate an improvement of power output and efficiency of about 10%. A four cylinder double acting Stirling engine is basically...

  8. Trace element and isotopic compositions of Vietnamese basalts: implications for mantle dynamics in the southeast Asian region

    International Nuclear Information System (INIS)

    Nguyen, H.; Fower, M.; Nguyen, H.; Nguyen, X.B.; Nguyen, T.Y.

    1996-01-01

    Cenozoic basalts in Indo-China are part of a regional melting episode along the rifted Eurasian margin. Trace element and isotopic compositions of Vietnamese basalts are used to place constraints on the extent of lithospheric and asthenosphere contributions to the melts and possible mantle dynamic implications. The 87 Sr/ 86 Sr, 207 Pb/ 204 Pb, and 208 Pb/ 204 Pb isotopic ratios of the basalts reflect minimal crustal wall rock reaction, and variable enrichment in EM1 and EM2 of a 208 Pb-rich MORB-like source. Some, but not all, of this variation corresponds to the age of lithospheric sector penetrated. Basalts erupted through a cratonic, central sector (e.g. at Quang Ngai, Pleiku, Song Cau, Kong Plong, and Buon Ma Thuot) and off-cratonic, southwest sector (e.g. Phuoc Long) resemble those of EM2-rich basalts from southern and southeaster China and the South China Sea. Basalts from an off-cratonic, southeast sector (e.g. from Dalat, Xuan Loc, and the offshore Ile des Cendres-Phu Cuy complex) reflect mixing between a low- 206 Pb/ 204 Pb, high- 208 Pb/ 204 Pb, EM1-like component, and resemble basalts from northwest Taiwan, eastern and northeastern China, and parts of the Japan Sea. While EM2 tends to characterise lithospheric sectors, presence of EM1 in off-cratonic rather than cratonic basalts implies an asthenosphere rather than lithospheric source. Pervasive presence of EM1 in southeast Asian and marginal basin asthenosphere corresponds with thermally-anomalous mantle and may involve delaminated cratonic substrate entrained by mobile, extruded asthenosphere. (authors)

  9. Performance assessment and optimization of an irreversible nano-scale Stirling engine cycle operating with Maxwell-Boltzmann gas

    Science.gov (United States)

    Ahmadi, Mohammad H.; Ahmadi, Mohammad-Ali; Pourfayaz, Fathollah

    2015-09-01

    Developing new technologies like nano-technology improves the performance of the energy industries. Consequently, emerging new groups of thermal cycles in nano-scale can revolutionize the energy systems' future. This paper presents a thermo-dynamical study of a nano-scale irreversible Stirling engine cycle with the aim of optimizing the performance of the Stirling engine cycle. In the Stirling engine cycle the working fluid is an Ideal Maxwell-Boltzmann gas. Moreover, two different strategies are proposed for a multi-objective optimization issue, and the outcomes of each strategy are evaluated separately. The first strategy is proposed to maximize the ecological coefficient of performance (ECOP), the dimensionless ecological function (ecf) and the dimensionless thermo-economic objective function ( F . Furthermore, the second strategy is suggested to maximize the thermal efficiency ( η), the dimensionless ecological function (ecf) and the dimensionless thermo-economic objective function ( F). All the strategies in the present work are executed via a multi-objective evolutionary algorithms based on NSGA∥ method. Finally, to achieve the final answer in each strategy, three well-known decision makers are executed. Lastly, deviations of the outcomes gained in each strategy and each decision maker are evaluated separately.

  10. Experimental investigation of a thermoacoustic-Stirling refrigerator driven by a thermoacoustic-Stirling heat engine.

    Science.gov (United States)

    Luo, E C; Dai, W; Zhang, Y; Ling, H

    2006-12-22

    In this paper, a thermally-driven thermoacoustic refrigerator system without any moving part is reported. This refrigeration system consists of a thermoacoustic-Stirling heat engine and a thermoacoustic-Stirling refrigerator; that is, the former is the driving source for the latter. Both the subsystems are designed to operate on traveling-wave mode. In the experiment, it was found that the DC-flows had significant negative effect on the heat engine and the refrigerator. To suppress these DC-flows, two flexible membranes were inserted into the two subsystems and worked very well. Then extensive experiments were made to test the influence of different parameters on refrigeration performance of the whole system. The system has so far achieved a no-load temperature of -65 degrees C, a cooling capacity of about 270 W at -20 degrees C and 405 W at 0 degrees C; in fact, the result showed a good prospect of the refrigeration system in room-temperature cooling such as food refrigeration and air-conditioning.

  11. Use of carbon isotopes as tracer to estimate carbon dynamics in forest

    International Nuclear Information System (INIS)

    Atarashi-Andoh, Mariko; Koarashi, Jun; Ishizuka, Shigehiro; Hirai, Keizo

    2010-01-01

    Soil respiration is the sum of heterotrophic respiration (decomposition of soil organic matter and litter) and root respiration. These CO 2 sources may respond differently to the variation in environmental change. Hence, the production of CO 2 from each source needs to be estimated individually. In this study, we use radiocarbon signatures to partition soil respiration in a cool-temperate deciduous forest in Japan by means of an isotope mass balance approach. Monthly measurements of Δ 14 C in soil respiration were conducted using the closed chamber method. The Δ 14 C in root respiration was assumed to be the value equivalent to the present atmospheric CO 2 and the Δ 14 C in heterotrophic respiration was estimated from the depth profile of Δ 14 C in soil organic matter. The results showed the seasonal variation in each source; the contribution of root respiration increased in July, while the contribution of heterotrophic respiration increased with the rise in soil temperature in August. The annual CO 2 flux was calculated using temperature-CO 2 flux model and the hourly soil temperature data in the site. Based on the results, the contribution ratios of CO 2 sources to soil respiration were estimated as: 34% from litter decomposition, 31% from soil organic matter decomposition and 35% from root respiration. (author)

  12. Migration dynamics of clupeoids in the Schelde estuary: a stable isotope approach

    DEFF Research Database (Denmark)

    Guelinckx, J.; Maes, J.; De Brabandere, Loreto

    2006-01-01

    Large numbers of young of the year herring (Clupea harengus L.) and sprat (Sprattus sprattus (L.)) typically enter and remain within North Sea estuaries during the winter months. The main purpose of this study was to examine their migration dynamics between the North Sea and the Schelde estuary u...... is concluded the results support the hypothesis that migration to estuarine nurseries is individually based....

  13. Output characteristics of Stirling thermoacoustic engine

    International Nuclear Information System (INIS)

    Sun Daming; Qiu Limin; Wang Bo; Xiao Yong; Zhao Liang

    2008-01-01

    A thermoacoustic engine (TE), which converts thermal energy into acoustic power by the thermoacoustic effect, shows several advantages due to the absence of moving parts, such as high reliability and long lifetime associated with reduced manufacturing costs. Power output and efficiency are important criteria of the performance of a TE. In order to increase the acoustic power output and thermal efficiency of a Stirling TE, the acoustic power distribution in the engine is studied with the variable load method. It is found that the thermal efficiency is independent of the output locations along the engine under the same acoustic power output. Furthermore, when the pressure ratio is kept constant at one location along the TE, it is beneficial to increasing the thermal efficiency by exporting more acoustic power. With nitrogen of 2.5 MPa as working gas and the pressure ratio at the compliance of 1.20 in the experiments, the acoustic power is measured at the compliance and the resonator simultaneously. The maximum power output, thermal efficiency and exergy efficiency reach 390.0 W, 11.2% and 16.0%, which are increased by 51.4%, 24.4% and 19.4%, respectively, compared to those with a single R-C load with 750 ml reservoir at the compliance. This research will be instructive for increasing the efficiency and making full use of the acoustic energy of a TE

  14. Stirling/hydraulic artificial heart power source

    International Nuclear Information System (INIS)

    Johnston, R.P.; Bennett, A.; Emigh, S.G.; Griffith, W.R.; Noble, J.E.; Perrone, R.E.; White, M.A.; Martini, W.R.; Alexander, J.E.

    1977-01-01

    The REL power source combines the high efficiency of Stirling engines with the reliability, efficiency, and flexibility of hydraulic power transfer and control to ensure long system life and physiological effectiveness. Extended life testing has been achieved with an engine (2.6 years) and hydraulic actuator/controller (1.6 years). Peak power source efficiency is 15.5 percent on 5 to 10 watts delivered to the blood pump push plate with 33 watts steady thermal input. Planned incorporation of power source output control is expected to reduce daily average thermal input to 18 watts. Animal in-vivo tests with an assist heart have consistently demonstrated required performance by biological synchronization and effective ventricle relief. Volume and weight are 0.93 liter and 2.4 kg (excluding blood pump) with an additional 0.4 liter of low temperature foam insulation required to preclude tissue thermal damage. Carefully planned development of System 7 is expected to produce major reductions in size

  15. Linear Generator for a Free Piston Stirling Engine

    Directory of Open Access Journals (Sweden)

    OROS (POP Teodora Susana

    2014-05-01

    Full Text Available In this paper we present some aspects about the design of a Stirling engine driven linear generator. There are summarised the main steps of the magnetic and electric calculations with application to a particular case of a cogeneration plant bassed on Stirling engine. The designed linear generator is of fixed coil and moving magnets type. There are presented and a finite element method (FEM simulation of magnetic field. The linear generator design starts with the characteristics of the rare earth permanent magnets existing on the market.

  16. Simulation of Temperature Fluctuations in Stirling Engine Regenerator Matrices

    DEFF Research Database (Denmark)

    Andersen, Stig Kildegaard; Carlsen, Henrik; Thomsen, Per Grove

    2003-01-01

    The objective of this study has been to create a model for studying the effects of fluctuations in regenerator matrix temperatures on Stirling engine performance. A one-dimensional model with axial discretisation of engine components has been formulated using the balance equations for mass, energy...... and accurately calculated. Simulation results have been compared to experimental data for a 9 kW Stirling engine and reasonable agreement has been found over a wide range of operating conditions using Helium or Nitrogen as working gas. Simulation results indicate that fluctuations in the regenerator matrix...... temperatures have significant impact on the regenerator loss, the engine power output, and the cycle efficiency....

  17. Evaluation Of Different Power Conditioning Options For Stirling Generators

    Science.gov (United States)

    Garrigos, A.; Blanes, J. M.; Carrasco, J. A.; Maset, E.; Montalban, G.; Ejea, J.; Ferreres, A.; Sanchis, E.

    2011-10-01

    Free-piston Stirling engines are an interesting alternative for electrical power systems, especially in deep space missions where photovoltaic systems are not feasible. This kind of power generators contains two main parts, the Stirling machine and the linear alternator that converts the mechanical energy from the piston movement to electrical energy. Since the generated power is in AC form, several aspects should be assessed to use such kind of generators in a spacecraft power system: AC/DC topologies, power factor correction, power regulation techniques, integration into the power system, etc. This paper details power generator operation and explores different power conversion approaches.

  18. Four-Cylinder Stirling-Engine Computer Program

    Science.gov (United States)

    Daniele, C. J.; Lorenzo, C. F.

    1986-01-01

    Computer program developed for simulating steady-state and transient performance of four-cylinder Stirling engine. In model, four cylinders interconnected by four working spaces. Each working space contains seven volumes: one for expansion space, heater, cooler, and compression space and three for regenerator. Thermal time constant for regenerator mass associated with each regenator gas volume. Former code generates results very quickly, since it has only 14 state variables with no energy equation. Current code then used to study various aspects of Stirling engine in much more detail. Program written in FORTRAN IV for use on IBM 370 computer.

  19. The application of inductively coupled plasma dynamic reaction cell mass spectrometry for measurement of selenium isotopes, isotope ratios and chromatographic detection of selenoamino acids

    DEFF Research Database (Denmark)

    Sloth, Jens Jørgen; Larsen, Erik Huusfeldt

    2000-01-01

    orders of magnitude by using methane as reactive cell gas in the DRC. By using 3% v/v methanol in water for carbon-enhanced ionisation of selenium, the sensitivity of Se-80 was 10(4) counts s(-1) per ng ml(-1) of selenium, and the estimated limit of detection was 6 pg ml(-1). The precision of the isotope...

  20. Thermodynamic Performance of Heat Exchangers in a Free Piston Stirling Engine

    Directory of Open Access Journals (Sweden)

    Ayodeji Sowale

    2018-02-01

    Full Text Available There is an increasing request in energy recovery systems that are more efficient, environmentally friendly and economical. The free piston Stirling engine has been investigated due to its structural simplicity and high efficiency, coupled with its cogeneration ability. This study presents the numerical investigation of quasi-steady model of a gamma type free piston Stirling engine (FPSE, including the thermodynamic analysis of the heat exchangers. Advanced thermodynamic models are employed to derive the initial set of operational parameters of the FPSE due to the coupling of the piston’s (displacer and piston dynamics and the working process. The proximity effect of the heater and cooler on the regenerator effectiveness in relation to the heat losses, output power, net work and thermal efficiency of the FPSE are also observed and presented in this study. It can be observed that at temperatures of 541.3 °C and 49.8 °C of the heater and cooler, respectively, with heater volume of 0.004 m3, regenerator volume of 0.003 m3 and cooler volume of 0.005 m3, the FPSE produced an output performance of 996.7 W with a thermal efficiency of 23% at a frequency of 30 Hz. This approach can be employed to design effective high performance FPSE due to their complexity and also predict a satisfactory performance.

  1. Investigations on materials for small Stirling refrigerators in long-term operation

    International Nuclear Information System (INIS)

    Engelland, W.; Kose, V.

    1990-04-01

    Work is being carried out world-wide on the development of refrigerators with low power requirements for the cooling of high-temperature superconductors and other cryoelectronic components. Due to its good efficiency factor, the well-known Stirling principle is particularly suitable for this purpose, but the increasing contamination of the working gases needed for the process which is caused by outgassing and the permeability to gas of the epoxide resins and other materials generally used makes it prone to interference over long periods of operation. For the first time, DURAN glass has been taken as a regenerator material and tested with successful results over a long period of operation in a small Stirling refrigerator designed and constructed for this purpose. A commercial double-membrane compressor which was also to be tested in long-term operation was converted into a dynamic pressure source and used as a refrigerator component. With this refrigerator, it was possible to maintain a temperature of 34 K over a continous period of operation of 77 days. Parallel to this, mass spectrometric permeation measurements were carried out on a compressor membrane made of VITON in which the water vapour of the atmosphere dominated. (orig.) [de

  2. The Development of a Control System for a 5 Kilowatt Free Piston Stirling Space Convertor

    International Nuclear Information System (INIS)

    Kirby, Raymond L.; Vitale, N.

    2008-01-01

    The new NASA Vision for Exploration, announced by President Bush in January 2004, proposes an ambitious program that plans to return astronauts to the moon by the 2018 time frame. A recent NASA study entitled 'Affordable Fission Surface Power Study' recommended a 40 kWe, 900 K, NaK-cooled, Stirling conversion for 2020 launch. Use of two of the nominal 5 kW converters allows the system to be dynamically balanced. A group of four dual-converter combinations that would yield 40 kWe can be tested to validate the viability of Stirling technology for space fission surface power systems. The work described in this paper deals specifically with the control system for the 5 kW convertor described in the preceding paragraph. This control system is responsible for maintaining piston stroke to a setpoint in the presence of various disturbances including electrical load variations. Pulse starting of the FSPE convertor is also an inherent part of such a control system. Finally, the ability to throttle the engine to match the required output power is discussed in terms of setpoint control. Several novel ideas have been incorporated into the piston stroke control strategy that will engender a stable response to disturbances in the presence of midpoint drift while providing useful data regarding the position of both the power piston and displacer

  3. Development of a miniature Stirling cryocooler for LWIR small satellite applications

    Science.gov (United States)

    Kirkconnell, C. S.; Hon, R. C.; Perella, M. D.; Crittenden, T. M.; Ghiaasiaan, S. M.

    2017-05-01

    The optimum small satellite (SmallSat) cryocooler system must be extremely compact and lightweight, achieved in this paper by operating a linear cryocooler at a frequency of approximately 300 Hz. Operation at this frequency, which is well in excess of the 100-150 Hz reported in recent papers on related efforts, requires an evolution beyond the traditional Oxford-class, flexure-based methods of setting the mechanical resonance. A novel approach that optimizes the electromagnetic design and the mechanical design together to simultaneously achieve the required dynamic and thermodynamic performances is described. Since highly miniaturized pulse tube coolers are fundamentally ill-suited for the sub-80K temperature range of interest because the boundary layer losses inside the pulse tube become dominant at the associated very small pulse tube size, a moving displacer Stirling cryocooler architecture is used. Compact compressor mechanisms developed on a previous program are reused for this design, and they have been adapted to yield an extremely compact Stirling warm end motor mechanism. Supporting thermodynamic and electromagnetic analysis results are reported.

  4. Dynamics of the reaction of the N+ ion with hydrogen isotopes and helium

    International Nuclear Information System (INIS)

    Ruska, W.E.W.

    1976-01-01

    Molecular beam techniques were used to study the reactive and non-reactive scattering of the nitrogen positive ion from hydrogen isotopes and helium, at energies above the stability limit for spectator stripping. Reactive scattering was observed from H 2 and HD targets. Non-reactive scattering was observed from H 2 and D 2 targets, and from He at one energy. A correlation diagram for the system is presented and compared with the available a priori calculations. Two surfaces are expected to lead to reaction. One is a 3 A 2 - 3 PI surface, the other, a 3 B 1 - 3 Σ - surface. Collinear approaches are expected to be most reactive on the 3 B 1 - 3 Σ - surface; noncollinear, on the 3 A 1 - 3 PI surface. Theoretical models are presented in which an incident hard sphere A, representing the projectile ion, strikes one of a pair of hard spheres B-C representing the B hydrogen molecule. After an impulsive A-B collision, an impulsive B-C collision may take place. The relative energy of A to B is then examined, and a reactive event is considered to have occurred if the energy is less than the dissociation energy for the A-B molecule. This model is treated both in the collinear case and in three dimensions. A graphical technique for the collinear case is summarized and applied to reaction on the 3 B 1 - 3 Σ - surface. An integral equation for the three-dimensional case is developed. A synthesis of two treatments, representing the behavior of the system on both reactive surfaces, and considering the charge-exchange channel, correctly predicts the observed product distribution. Predictions are also presented for the as yet unobserved case of reactive scattering from a D 2 target

  5. Continuous administration of short-lived isotopes for evaluating dynamic parameters

    International Nuclear Information System (INIS)

    Selikson, M.

    1985-01-01

    In this paper it is shown that continuous but varying infusions (specifically, exponential infusions) of a short-lived radionuclide can be used to evaluate a wide range of dynamic parameters. The detector response to exponential infusions is derived. An example of an inert diffusible substrate for evaluating regional flow and a glucose model for evaluating regional metabolic rate are both worked out. The advantages of using exponential infusion methods are discussed

  6. Impact of seaweed beachings on dynamics of δ15N isotopic signatures in marine macroalgae

    International Nuclear Information System (INIS)

    Lemesle, Stéphanie; Mussio, Isabelle; Rusig, Anne-Marie; Menet-Nédélec, Florence; Claquin, Pascal

    2015-01-01

    Highlights: • Two coastal sites (COU, GM) in the Bay of Seine affected by summer seaweed beachings. • The same temporal dynamics of the algal δ 15 N at the two sites. • N and P concentrations in seawater of the two sites dominated by riverine sources. • A coupling between seaweed beachings and N sources of intertidal macroalgae. - Abstract: A fine-scale survey of δ 15 N, δ 13 C, tissue-N in seaweeds was conducted using samples from 17 sampling points at two sites (Grandcamp-Maisy (GM), Courseulles/Mer (COU)) along the French coast of the English Channel in 2012 and 2013. Partial triadic analysis was performed on the parameter data sets and revealed the functioning of three areas: one estuary (EstA) and two rocky areas (GM ∗ , COU ∗ ). In contrast to oceanic and anthropogenic reference points similar temporal dynamics characterized δ 15 N signatures and N contents at GM ∗ and COU ∗ . Nutrient dynamics were similar: the N-concentrations in seawater originated from the River Seine and local coastal rivers while P-concentrations mainly from these local rivers. δ 15 N at GM ∗ were linked to turbidity suggesting inputs of autochthonous organic matter from large-scale summer seaweed beachings made up of a mixture of Rhodophyta, Phaeophyta and Chlorophyta species. This study highlights the coupling between seaweed beachings and nitrogen sources of intertidal macroalgae

  7. Dynamics of the reaction of the N/sup +/ ion with hydrogen isotopes and helium

    Energy Technology Data Exchange (ETDEWEB)

    Ruska, W.E.W.

    1976-06-28

    Molecular beam techniques were used to study the reactive and non-reactive scattering of the nitrogen positive ion from hydrogen isotopes and helium, at energies above the stability limit for spectator stripping. Reactive scattering was observed from H/sub 2/ and HD targets. Non-reactive scattering was observed from H/sub 2/ and D/sub 2/ targets, and from He at one energy. A correlation diagram for the system is presented and compared with the available a priori calculations. Two surfaces are expected to lead to reaction. One is a /sup 3/A/sub 2/ - /sup 3/PI surface, the other, a /sup 3/B/sub 1/ - /sup 3/..sigma../sup -/ surface. Collinear approaches are expected to be most reactive on the /sup 3/B/sub 1/ - /sup 3/..sigma../sup -/ surface; noncollinear, on the /sup 3/A/sub 1/ - /sup 3/PI surface. Theoretical models are presented in which an incident hard sphere A, representing the projectile ion, strikes one of a pair of hard spheres B-C representing the B hydrogen molecule. After an impulsive A-B collision, an impulsive B-C collision may take place. The relative energy of A to B is then examined, and a reactive event is considered to have occurred if the energy is less than the dissociation energy for the A-B molecule. This model is treated both in the collinear case and in three dimensions. A graphical technique for the collinear case is summarized and applied to reaction on the /sup 3/B/sub 1/ - /sup 3/..sigma../sup -/ surface. An integral equation for the three-dimensional case is developed. A synthesis of two treatments, representing the behavior of the system on both reactive surfaces, and considering the charge-exchange channel, correctly predicts the observed product distribution. Predictions are also presented for the as yet unobserved case of reactive scattering from a D/sub 2/ target.

  8. Impact of seaweed beachings on dynamics of δ(15)N isotopic signatures in marine macroalgae.

    Science.gov (United States)

    Lemesle, Stéphanie; Mussio, Isabelle; Rusig, Anne-Marie; Menet-Nédélec, Florence; Claquin, Pascal

    2015-08-15

    A fine-scale survey of δ(15)N, δ(13)C, tissue-N in seaweeds was conducted using samples from 17 sampling points at two sites (Grandcamp-Maisy (GM), Courseulles/Mer (COU)) along the French coast of the English Channel in 2012 and 2013. Partial triadic analysis was performed on the parameter data sets and revealed the functioning of three areas: one estuary (EstA) and two rocky areas (GM(∗), COU(∗)). In contrast to oceanic and anthropogenic reference points similar temporal dynamics characterized δ(15)N signatures and N contents at GM(∗) and COU(∗). Nutrient dynamics were similar: the N-concentrations in seawater originated from the River Seine and local coastal rivers while P-concentrations mainly from these local rivers. δ(15)N at GM(∗) were linked to turbidity suggesting inputs of autochthonous organic matter from large-scale summer seaweed beachings made up of a mixture of Rhodophyta, Phaeophyta and Chlorophyta species. This study highlights the coupling between seaweed beachings and nitrogen sources of intertidal macroalgae. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Vibrational relaxation dynamics of SD molecules in As2S3: Observation of an anomalous isotope effect

    International Nuclear Information System (INIS)

    Engholm, J.R.; Happek, U.; Rella, C.W.

    1995-01-01

    It is generally assumed that the vibrational relaxation of molecular impurities in crystals and glasses mainly depends on the order of the decay process, with lower order processes leading to more rapid relaxation (a behavior that is known under the term open-quotes gap-lawclose quotes). Here we present measurements that contradict this assumption. Using high intensity psec pulses of the Stanford FEL we measured the relaxation rate of the SD vibrational stretch mode (at a frequency of 1800 cm) by applying a pump-probe technique. We find relaxation rates on the order of 2x10 9 sec -1 , which are a factor of 2 lower than those found for the isotope molecule SH (at a frequency of about 2500 cm - 1 ) in the same host 1 . We recall that the relaxation of the SD vibrational stretch mode is controlled by a lower order process as compared to the SH molecule, which is due to the smaller number of host vibrational quanta to match the energy of the stretch mode; a fact we have confirmed experimentally by temperature dependent relaxation measurements. Thus our remits are in marked contrast to the so-called open-quotes Gap-Lawclose quotes and emphasize the importance of the molecule - host coupling in the relaxation dynamics

  10. Molecular biological and isotopic biogeochemical prognoses of the nitrification-driven dynamic microbial nitrogen cycle in hadopelagic sediments.

    Science.gov (United States)

    Nunoura, Takuro; Nishizawa, Manabu; Kikuchi, Tohru; Tsubouchi, Taishi; Hirai, Miho; Koide, Osamu; Miyazaki, Junichi; Hirayama, Hisako; Koba, Keisuke; Takai, Ken

    2013-11-01

    There has been much progress in understanding the nitrogen cycle in oceanic waters including the recent identification of ammonia-oxidizing archaea and anaerobic ammonia oxidizing (anammox) bacteria, and in the comprehensive estimation in abundance and activity of these microbial populations. However, compared with the nitrogen cycle in oceanic waters, there are fewer studies concerning the oceanic benthic nitrogen cycle. To further elucidate the dynamic nitrogen cycle in deep-sea sediments, a sediment core obtained from the Ogasawara Trench at a water depth of 9760 m was analysed in this study. The profiles obtained for the pore-water chemistry, and nitrogen and oxygen stable isotopic compositions of pore-water nitrate in the hadopelagic sediments could not be explained by the depth segregation of nitrifiers and nitrate reducers, suggesting the co-occurrence of nitrification and nitrate reduction in the shallowest nitrate reduction zone. The abundance of SSU rRNA and functional genes related to nitrification and denitrification are consistent with the co-occurrence of nitrification and nitrate reduction observed in the geochemical analyses. This study presents the first example of cooperation between aerobic and anaerobic nitrogen metabolism in the deep-sea sedimentary environments. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. Multiple Cylinder Free-Piston Stirling Machinery

    Science.gov (United States)

    Berchowitz, David M.; Kwon, Yong-Rak

    In order to improve the specific power of piston-cylinder type machinery, there is a point in capacity or power where an advantage accrues with increasing number of piston-cylinder assemblies. In the case of Stirling machinery where primary energy is transferred across the casing wall of the machine, this consideration is even more important. This is due primarily to the difference in scaling of basic power and the required heat transfer. Heat transfer is found to be progressively limited as the size of the machine increases. Multiple cylinder machines tend to preserve the surface area to volume ratio at more favorable levels. In addition, the spring effect of the working gas in the so-called alpha configuration is often sufficient to provide a high frequency resonance point that improves the specific power. There are a number of possible multiple cylinder configurations. The simplest is an opposed pair of piston-displacer machines (beta configuration). A three-cylinder machine requires stepped pistons to obtain proper volume phase relationships. Four to six cylinder configurations are also possible. A small demonstrator inline four cylinder alpha machine has been built to demonstrate both cooling operation and power generation. Data from this machine verifies theoretical expectations and is used to extrapolate the performance of future machines. Vibration levels are discussed and it is argued that some multiple cylinder machines have no linear component to the casing vibration but may have a nutating couple. Example applications are discussed ranging from general purpose coolers, computer cooling, exhaust heat power extraction and some high power engines.

  12. Isotopic research in Antarctica

    International Nuclear Information System (INIS)

    Schuetze, H.

    1983-01-01

    Since 1978 scientists of the Central Institute of Isotope- and Radiation Research of the Academy of Sciences of the GDR have participated in antarctic research. Substantial results have been achieved in research on isotope ratios, on the dynamics of water resources, on concentration of deuterium in lichens, and on age determination of a mummified seal and a penguin colony

  13. Automotive Stirling engine development program. [fuel economy assessment

    Science.gov (United States)

    Kitzner, E. W.

    1978-01-01

    The Ford/DOE automotive Stirling engine development program is directed towards establishing the technological and developmental base that would enable a decision on whether an engineering program should be directed at Stirling engine production. The fuel economy assessment aims to achieve, with a high degree of confidence, the ERDA proposal estimate of 20.6 MPG (gasoline) for a 4500 lb 1WC Stirling engine passenger car. The current M-H fuel economy projection for the 170 HP Stirling engine is 15.7 MPG. The confidence level for this projection is 32%. A confidence level of 29% is projected for a 22.1 MPG estimate. If all of the planned analyses and test work is accomplished at the end of the one year effort, and the projected improvements are substantiated, the confidence levels would rise to 59% for the 20.6 MPG projection and 54% for the 22.1 MPG projection. Progress achieved thus far during the fuel economy assessment is discussed.

  14. How to Overcome Numerical Challenges to Modeling Stirling Engines

    Science.gov (United States)

    Dyson, Rodger W.; Wilson, Scott D.; Tew, Roy C.

    2004-01-01

    Nuclear thermal to electric power conversion carries the promise of longer duration missions and higher scientific data transmission rates back to Earth for a range of missions, including both Mars rovers and deep space missions. A free-piston Stirling convertor is a candidate technology that is considered an efficient and reliable power conversion device for such purposes. While already very efficient, it is believed that better Stirling engines can be developed if the losses inherent in current designs could be better understood. However, they are difficult to instrument and so efforts are underway to simulate a complete Stirling engine numerically. This has only recently been attempted and a review of the methods leading up to and including such computational analysis is presented. And finally it is proposed that the quality and depth of Stirling loss understanding may be improved by utilizing the higher fidelity and efficiency of recently developed numerical methods. One such method, the Ultra HI-FI technique is presented in detail.

  15. Experimental and theoretical investigation of Stirling engine heater: Parametrical optimization

    International Nuclear Information System (INIS)

    Gheith, R.; Hachem, H.; Aloui, F.; Ben Nasrallah, S.

    2015-01-01

    Highlights: • A Stirling engine was investigated to optimize its operation and its performance. • The porous medium present the highest amount of heat exchanged in a Stirling engine. • The heater characteristics are determinant points to enhance the thermal exchange in Stirling engine. • All operation parameters influence the heater performances. • Thermal and exergy heater efficiencies are sensible to temperature and pressure. - Abstract: The aim of this work is to optimize γ Stirling engine performances with a special care given to the heater. This latter consists of 20 tubes in order to increase the exchange area between the working gas and the hot source. Different parameters were chosen to evaluate numerically and experimentally the heater. The selected four independent parameters are: heating temperature (300–500 °C), initial filling pressure (3–8 bar), cooling water flow rate (0.2–3 l/min) and frequency (2–7 Hz). The amount of energy exchanged in the heater is significantly influenced by the frequency and heating temperature but it is slightly enhanced with the increase in the cooling water flow rate. The thermal and the exergy efficiencies of the heater are very sensible to the temperature and pressure variations.

  16. Maximum Work of Free-Piston Stirling Engine Generators

    Science.gov (United States)

    Kojima, Shinji

    2017-04-01

    Using the method of adjoint equations described in Ref. [1], we have calculated the maximum thermal efficiencies that are theoretically attainable by free-piston Stirling and Carnot engine generators by considering the work loss due to friction and Joule heat. The net work done by the Carnot cycle is negative even when the duration of heat addition is optimized to give the maximum amount of heat addition, which is the same situation for the Brayton cycle described in our previous paper. For the Stirling cycle, the net work done is positive, and the thermal efficiency is greater than that of the Otto cycle described in our previous paper by a factor of about 2.7-1.4 for compression ratios of 5-30. The Stirling cycle is much better than the Otto, Brayton, and Carnot cycles. We have found that the optimized piston trajectories of the isothermal, isobaric, and adiabatic processes are the same when the compression ratio and the maximum volume of the same working fluid of the three processes are the same, which has facilitated the present analysis because the optimized piston trajectories of the Carnot and Stirling cycles are the same as those of the Brayton and Otto cycles, respectively.

  17. Structural Benchmark Testing for Stirling Convertor Heater Heads

    Science.gov (United States)

    Krause, David L.; Kalluri, Sreeramesh; Bowman, Randy R.

    2007-01-01

    The National Aeronautics and Space Administration (NASA) has identified high efficiency Stirling technology for potential use on long duration Space Science missions such as Mars rovers, deep space missions, and lunar applications. For the long life times required, a structurally significant design limit for the Stirling convertor heater head is creep deformation induced even under relatively low stress levels at high material temperatures. Conventional investigations of creep behavior adequately rely on experimental results from uniaxial creep specimens, and much creep data is available for the proposed Inconel-718 (IN-718) and MarM-247 nickel-based superalloy materials of construction. However, very little experimental creep information is available that directly applies to the atypical thin walls, the specific microstructures, and the low stress levels. In addition, the geometry and loading conditions apply multiaxial stress states on the heater head components, far from the conditions of uniaxial testing. For these reasons, experimental benchmark testing is underway to aid in accurately assessing the durability of Stirling heater heads. The investigation supplements uniaxial creep testing with pneumatic testing of heater head test articles at elevated temperatures and with stress levels ranging from one to seven times design stresses. This paper presents experimental methods, results, post-test microstructural analyses, and conclusions for both accelerated and non-accelerated tests. The Stirling projects use the results to calibrate deterministic and probabilistic analytical creep models of the heater heads to predict their life times.

  18. Characterization of the Advanced Stirling Radioisotope Generator Engineering Unit 2

    Science.gov (United States)

    Lewandowski, Edward J.; Oriti, Salvatore M.; Schifer, Niholas A.

    2016-01-01

    Significant progress was made developing the Advanced Stirling Radioisotope Generator (ASRG) 140-W radioisotope power system. While the ASRG flight development project has ended, the hardware that was designed and built under the project is continuing to be tested to support future Stirling-based power system development. NASA Glenn Research Center recently completed the assembly of the ASRG Engineering Unit 2 (EU2). The ASRG EU2 consists of the first pair of Sunpower's Advanced Stirling Convertor E3 (ASC-E3) Stirling convertors mounted in an aluminum housing, and Lockheed Martin's Engineering Development Unit (EDU) 4 controller (a fourth-generation controller). The ASC-E3 convertors and Generator Housing Assembly (GHA) closely match the intended ASRG Qualification Unit flight design. A series of tests were conducted to characterize the EU2, its controller, and the convertors in the flight-like GHA. The GHA contained an argon cover gas for these tests. The tests included measurement of convertor, controller, and generator performance and efficiency; quantification of control authority of the controller; disturbance force measurement with varying piston phase and piston amplitude; and measurement of the effect of spacecraft direct current (DC) bus voltage on EU2 performance. The results of these tests are discussed and summarized, providing a basic understanding of EU2 characteristics and the performance and capability of the EDU 4 controller.

  19. Advanced Controller for the Free-Piston Stirling Convertor

    Science.gov (United States)

    Gerber, Scott S.; Jamison, Mike; Roth, Mary Ellen; Regan, Timothy F.

    2004-01-01

    The free-piston Stirling power convertor is being considered as an advanced power conversion technology to be used for future NASA deep space missions requiring long life radioisotope power systems. This technology has a conversion efficiency of over 25%, which is significantly higher than the efficiency of the Radioisotope Thermal-electric Generators (RTG) now in use. The NASA Glenn Research Center has long been recognized as a leader in Stirling technology and is responsible for the development of advanced technologies that are intended to significantly improve key characteristics of the Stirling convertor. The advanced technologies identified for development also consider the requirements of potential future missions and the new capabilities that have become available in the associated technical areas. One of the key areas identified for technology development is the engine controller. To support this activity, an advanced controller is being developed for the Stirling power convertor. This controller utilizes active power factor correction electronics and microcontroller-based controls. The object of this paper is to present an overview of the advanced controller concept with modeling, simulation and hardware test data.

  20. Advanced Controller Developed for the Free-Piston Stirling Convertor

    Science.gov (United States)

    Gerber, Scott S.

    2005-01-01

    A free-piston Stirling power convertor is being considered as an advanced power-conversion technology for future NASA deep-space missions requiring long-life radioisotope power systems. The NASA Glenn Research Center has identified key areas where advanced technologies can enhance the capability of Stirling energy-conversion systems. One of these is power electronic controls. Current power-conversion technology for Glenn-tested Stirling systems consists of an engine-driven linear alternator generating an alternating-current voltage controlled by a tuning-capacitor-based alternating-current peak voltage load controller. The tuning capacitor keeps the internal alternator electromotive force (EMF) in phase with its respective current (i.e., passive power factor correction). The alternator EMF is related to the piston velocity, which must be kept in phase with the alternator current in order to achieve stable operation. This tuning capacitor, which adds volume and mass to the overall Stirling convertor, can be eliminated if the controller can actively drive the magnitude and phase of the alternator current.

  1. Thermodynamic comparison of Peltier, Stirling, and vapor compression portable coolers

    International Nuclear Information System (INIS)

    Hermes, Christian J.L.; Barbosa, Jader R.

    2012-01-01

    Highlights: ► A Peltier, a Stirling, and two vapor compression refrigerators were compared. ► Tests were carried out to obtain key performance parameters of the systems. ► The overall 2nd-law efficiency was splited to take into account the internal and external irreversibilities. ► The Stirling and vapor compression refrigeration systems presented higher efficiencies. ► The thermoelectric device was not at the same efficiency level as the other coolers. -- Abstract: The present study compares the thermodynamic performance of four small-capacity portable coolers that employ different cooling technologies: thermoelectric, Stirling, and vapor compression using two different compressors (reciprocating and linear). The refrigeration systems were experimentally evaluated in a climatized chamber with controlled temperature and humidity. Tests were carried out at two different ambient temperatures (21 and 32 °C) in order to obtain key performance parameters of the systems (e.g., power consumption, cooling capacity, internal air temperature, and the hot end and cold end temperatures). These performance parameters were compared using a thermodynamic approach that splits the overall 2nd law efficiency into two terms, namely, the internal and external efficiencies. In doing so, the internal irreversibilities (e.g., friction in the working fluid in the Stirling and vapor compression machines, Joule heating and heat conduction in the thermoelectric devices of the Peltier cooler) were separated from the heat exchanger losses (external irreversibilities), allowing the comparison between different refrigeration technologies with respect to the same thermodynamic baseline.

  2. Radioisotope power system based on derivative of existing Stirling engine

    International Nuclear Information System (INIS)

    Schock, A.; Or, C.T.; Kumar, V.

    1995-01-01

    In a recent paper, the authors presented the results of a system design study of a 75-watt(c) RSG (Radioisotope Stirling Generator) for possible application to the Pluto Fast Flyby mission. That study was based on a Stirling engine design generated by MTI (Mechanical Technology, Inc.). The MTI design was a derivative of a much larger (13 kwe) engine that they had developed and tested for NASA's LERC. Clearly, such a derivative would be a major extrapolation (downsizing) from what has actually been built and tested. To avoid that, the present paper describes a design for a 75-watt RSG system based on derivatives of a small (11-watt) engine and linear alternator system that has been under development by STC (Stirling Technology Company) for over three years and that has operated successfully for over 15,000 hours as of March 1995. Thus, the STC engines would require much less extrapolation from proven designs. The design employs a heat source consisting of two standard General Purpose Heat Source (GPHS) modules, coupled to four Stirling engines with linear alternators, any three of which could deliver the desired 75-watt(e) output if the fourth should fail. The four engines are coupled to four common radiators with redundant heatpipes for rejecting the engines' waste heat to space. The above engine and radiator redundancies promote system reliability. The paper describes detailed analyses to determine the effect of radiator geometry on system mass and performance, before and after an engine or heatpipe failure

  3. Technology development for a Stirling radioisotope power system

    International Nuclear Information System (INIS)

    Thieme, Lanny G.; Qiu, Songgang; White, Maurice A.

    2000-01-01

    NASA Glenn Research Center and the Department of Energy are developing a Stirling convertor for an advanced radioisotope power system to provide spacecraft on-board electric power for NASA deep space missions. NASA Glenn is addressing key technology issues through the use of two NASA Phase II SBIRs with Stirling Technology Company (STC) of Kennewick, WA. Under the first SBIR, STC demonstrated a synchronous connection of two thermodynamically independent free-piston Stirling convertors and a 40 to 50 fold reduction in vibrations compared to an unbalanced convertor. The second SBIR is for the development of an Adaptive Vibration Reduction System (AVRS) that will essentially eliminate vibrations over the mission lifetime, even in the unlikely event of a failed convertor. This paper presents the status and results for these two SBIR projects and also discusses a new NASA Glenn in-house project to provide supporting technology for the overall Stirling radioisotope power system development. Tasks for this new effort include convertor performance verification, controls development, heater head structural life assessment, magnet characterization and thermal aging tests, FEA analysis for a lightweight alternator concept, and demonstration of convertor operation under launch and orbit transfer load conditions

  4. Degenerate r-Stirling Numbers and r-Bell Polynomials

    Science.gov (United States)

    Kim, T.; Yao, Y.; Kim, D. S.; Jang, G.-W.

    2018-01-01

    The purpose of this paper is to exploit umbral calculus in order to derive some properties, recurrence relations, and identities related to the degenerate r-Stirling numbers of the second kind and the degenerate r-Bell polynomials. Especially, we will express the degenerate r-Bell polynomials as linear combinations of many well-known families of special polynomials.

  5. Operating single quantum emitters with a compact Stirling cryocooler.

    Science.gov (United States)

    Schlehahn, A; Krüger, L; Gschrey, M; Schulze, J-H; Rodt, S; Strittmatter, A; Heindel, T; Reitzenstein, S

    2015-01-01

    The development of an easy-to-operate light source emitting single photons has become a major driving force in the emerging field of quantum information technology. Here, we report on the application of a compact and user-friendly Stirling cryocooler in the field of nanophotonics. The Stirling cryocooler is used to operate a single quantum emitter constituted of a semiconductor quantum dot (QD) at a base temperature below 30 K. Proper vibration decoupling of the cryocooler and its surrounding enables free-space micro-photoluminescence spectroscopy to identify and analyze different charge-carrier states within a single quantum dot. As an exemplary application in quantum optics, we perform a Hanbury-Brown and Twiss experiment demonstrating a strong suppression of multi-photon emission events with g((2))(0) Stirling-cooled single quantum emitter under continuous wave excitation. Comparative experiments performed on the same quantum dot in a liquid helium (LHe)-flow cryostat show almost identical values of g((2))(0) for both configurations at a given temperature. The results of this proof of principle experiment demonstrate that low-vibration Stirling cryocoolers that have so far been considered exotic to the field of nanophotonics are an attractive alternative to expensive closed-cycle cryostats or LHe-flow cryostats, which could pave the way for the development of high-quality table-top non-classical light sources.

  6. Advanced Stirling Radioisotope Generator EU2 Anomaly Investigation

    Science.gov (United States)

    Lewandowski, Edward J.; Dobbs, Michael W.; Oriti, Salvatore M.

    2016-01-01

    The Advanced Stirling Radioisotope Generator (ASRG) Engineering Unit 2 (EU2) is the highest fidelity electrically-heated Stirling radioisotope generator built to date. NASA Glenn Research Center (GRC) completed the assembly of the ASRG EU2 in September, 2014 using hardware from the now cancelled ASRG flight development project. The ASRG EU2 integrated the first pair of Sunpower's ASC-E3 Stirling convertors (ASC-E3 #1 and #2) in an aluminum generator housing with Lockheed Martin's Engineering Development Unit (EDU) 4 controller. After just 179 hours of EU2 generator operation, the first power fluctuation occurred on ASC-E3 #1. The first power fluctuation occurred 175 hours later on ASC-E3 #2. Over time, the power fluctuations became more frequent on both convertors and larger in magnitude. Eventually the EU2 was shut down in January, 2015. An anomaly investigation was chartered to determine root cause of the power fluctuations and other anomalous observations. A team with members from GRC, Sunpower, and Lockheed Martin conducted a thorough investigation of the EU2 anomalies. Findings from the EU2 disassembly identified proximate causes of the anomalous observations. Discussion of the team's assessment of the primary possible failure theories, root cause, and conclusions is provided. Recommendations are made for future Stirling generator development to address the findings from the anomaly investigation. Additional findings from the investigation are also discussed.

  7. Extended Operation of Stirling Convertors at NASA Glenn Research Center

    Science.gov (United States)

    Oriti, Salvatore, M.

    2012-01-01

    NASA Glenn Research Center (GRC) has been supporting development of free-piston Stirling conversion technology for spaceflight electrical power generation since 1999. GRC has also been supporting the development of the Advanced Stirling Radioisotope Generator (ASRG) since 2006. A key element of the ASRG project is providing life, reliability, and performance data for the Advanced Stirling Convertor (ASC). The Thermal Energy Conversion branch at GRC is conducting extended operation of several free-piston Stirling convertors. The goal of this effort is to generate long-term performance data (tens of thousands of hours) on multiple units to build a life and reliability database. Currently, GRC is operating 18 convertors. This hardware set includes Technology Demonstration Convertors (TDCs) from Infinia Corporation, of which one pair (TDCs #13 and #14) has accumulated over 60,000 hr (6.8 years) of operation. Also under test are various Sunpower, Inc. convertors that were fabricated during the ASC development activity, including ASC-0, ASC-E (including those in the ASRG engineering unit), and ASC-E2. The ASC-E2s also completed, or are in progress of completing workmanship vibration testing, performance mapping, and extended operation. Two ASC-E2 units will also be used for durability testing, during which components will be stressed to levels above nominal mission usage. Extended operation data analyses from these tests are covered in this paper.

  8. Operating single quantum emitters with a compact Stirling cryocooler

    Energy Technology Data Exchange (ETDEWEB)

    Schlehahn, A.; Krüger, L.; Gschrey, M.; Schulze, J.-H.; Rodt, S.; Strittmatter, A.; Heindel, T., E-mail: tobias.heindel@tu-berlin.de; Reitzenstein, S. [Institute of Solid State Physics, Technische Universität Berlin, 10623 Berlin (Germany)

    2015-01-15

    The development of an easy-to-operate light source emitting single photons has become a major driving force in the emerging field of quantum information technology. Here, we report on the application of a compact and user-friendly Stirling cryocooler in the field of nanophotonics. The Stirling cryocooler is used to operate a single quantum emitter constituted of a semiconductor quantum dot (QD) at a base temperature below 30 K. Proper vibration decoupling of the cryocooler and its surrounding enables free-space micro-photoluminescence spectroscopy to identify and analyze different charge-carrier states within a single quantum dot. As an exemplary application in quantum optics, we perform a Hanbury-Brown and Twiss experiment demonstrating a strong suppression of multi-photon emission events with g{sup (2)}(0) < 0.04 from this Stirling-cooled single quantum emitter under continuous wave excitation. Comparative experiments performed on the same quantum dot in a liquid helium (LHe)-flow cryostat show almost identical values of g{sup (2)}(0) for both configurations at a given temperature. The results of this proof of principle experiment demonstrate that low-vibration Stirling cryocoolers that have so far been considered exotic to the field of nanophotonics are an attractive alternative to expensive closed-cycle cryostats or LHe-flow cryostats, which could pave the way for the development of high-quality table-top non-classical light sources.

  9. The κ-Generalizations of Stirling Approximation and Multinominal Coefficients

    Directory of Open Access Journals (Sweden)

    Tatsuaki Wada

    2013-11-01

    Full Text Available Stirling approximation of the factorials and multinominal coefficients are generalized based on the κ-generalized functions introduced by Kaniadakis. We have related the κ-generalized multinominal coefficients to the κ-entropy by introducing a new κ-product operation, which exists only when κ ≠ 0.

  10. Tsallis p, q-deformed Touchard polynomials and Stirling numbers

    Science.gov (United States)

    Herscovici, O.; Mansour, T.

    2017-01-01

    In this paper, we develop and investigate a new two-parametrized deformation of the Touchard polynomials, based on the definition of the NEXT q-exponential function of Tsallis. We obtain new generalizations of the Stirling numbers of the second kind and of the binomial coefficients and represent two new statistics for the set partitions.

  11. Advanced Stirling Radioisotope Generator Engineering Unit 2 Anomaly Investigation

    Science.gov (United States)

    Lewandowski, Edward J.; Dobbs, Michael W.; Oriti, Salvatore M.

    2018-01-01

    The Advanced Stirling Radioisotope Generator (ASRG) Engineering Unit 2 (EU2) is the highest fidelity electrically heated Stirling radioisotope generator built to date. NASA Glenn Research Center completed the assembly of the ASRG EU2 in September 2014 using hardware from the now cancelled ASRG flight development project. The ASRG EU2 integrated the first pair of Sunpower's Advanced Stirling Convertors (ASC-E3 #1 and #2) in an aluminum generator housing with Lockheed Martin's (LM's) Engineering Development Unit (EDU) 4 controller. After just 179 hr of EU2 generator operation, the first power fluctuation occurred on ASC-E3 #1. The first power fluctuation occurred 175 hr later on ASC-E3 #2. Over time, the power fluctuations became more frequent on both convertors and larger in magnitude. Eventually the EU2 was shut down in January 2015. An anomaly investigation was chartered to determine root cause of the power fluctuations and other anomalous observations. A team with members from Glenn, Sunpower, and LM conducted a thorough investigation of the EU2 anomalies. Findings from the EU2 disassembly identified proximate causes of the anomalous observations. Discussion of the team's assessment of the primary possible failure theories, root cause, and conclusions is provided. Recommendations are made for future Stirling generator development to address the findings from the anomaly investigation. Additional findings from the investigation are also discussed.

  12. Faunal isotope records reveal trophic and nutrient dynamics in twentieth century Yellowstone grasslands.

    Science.gov (United States)

    Fox-Dobbs, Kena; Nelson, Abigail A; Koch, Paul L; Leonard, Jennifer A

    2012-10-23

    Population sizes and movement patterns of ungulate grazers and their predators have fluctuated dramatically over the past few centuries, largely owing to overharvesting, land-use change and historic management. We used δ(13)C and δ(15)N values measured from bone collagen of historic and recent gray wolves and their potential primary prey from Yellowstone National Park to gain insight into the trophic dynamics and nutrient conditions of historic and modern grasslands. The diet of reintroduced wolves closely parallels that of the historic population. We suggest that a significant shift in faunal δ(15)N values over the past century reflects impacts of anthropogenic environmental changes on grassland ecosystems, including grazer-mediated shifts in grassland nitrogen cycle processes.

  13. The effect of pressure, isotopic (H/D) substitution, and other variables on miscibility in polymer-solvent systems. The nature of the demixing process; dynamic light scattering and small angle neutron scattering studies. Final report

    International Nuclear Information System (INIS)

    Van Hook, W.A.

    2000-01-01

    A research program examining the effects of pressure, isotope substitution and other variables on miscibility in polymer solvent systems is described. The techniques employed included phase equilibrium measurements and dynamic light scattering and small angle neutron scattering

  14. Brome isotope selective control of CF3Br molecule clustering by IR laser radiation in gas-dynamic expansion of CF3Br - Ar mixture

    Science.gov (United States)

    Apatin, V. M.; Lokhman, V. N.; Makarov, G. N.; Ogurok, N.-D. D.; Ryabov, E. A.

    2018-02-01

    We report the results of research on the experimental control of CF3Br molecule clustering under gas-dynamic expansion of the CF3Br - Ar mixture at a nozzle exit by using IR laser radiation. A cw CO2 laser is used for exciting molecules and clusters in the beam and a time-of-flight mass-spectrometer with laser UV ionisation of particles for their detection. The parameters of the gas above the nozzle are determined (compositions and pressure) at which intensive molecule clustering occurs. It is found that in the case of the CF3Br gas without carrier when the pressure P0 above the nozzle does not exceed 4 atm, molecular clusters actually are not generated in the beam. If the gas mixture of CF3Br with argon is used at a pressure ratio 1 : N, where N >= 3, and the total pressure above the nozzle is P0 >= 2 atm, then there occurs molecule clustering. We study the dependences of the efficiency of suppressing the molecule clustering on parameters of the exciting pulse, gas parameters above the nozzle, and on a distance of the molecule irradiation zone from the nozzle exit section. It is shown that in the case of resonant vibrational excitation of gas-dynamically cooled CF3Br molecules at the nozzle exit one can realise isotope-selective suppression of molecule clustering with respect to bromine isotopes. With the CF3Br - Ar mixtures having the pressure ratio 1 : 3 and 1 : 15, the enrichment factors obtained with respect to bromine isotopes are kenr ≈ 1.05 ± 0.005 and kenr ≈ 1.06 ± 0.007, respectively, under jet irradiation by laser emission in the 9R(30) line (1084.635 cm-1). The results obtained let us assume that this method can be used to control clustering of molecules comprising heavy element isotopes, which have a small isotopic shift in IR absorption spectra.

  15. Diverging effects of isotopic fractionation upon molecular diffusion of noble gases in water: mechanistic insights through ab initio molecular dynamics simulations.

    Science.gov (United States)

    Pinto de Magalhães, Halua; Brennwald, Matthias S; Kipfer, Rolf

    2017-03-22

    Atmospheric noble gases are routinely used as natural tracers to analyze gas transfer processes in aquatic systems. Their isotopic ratios can be employed to discriminate between different physical transport mechanisms by comparison to the unfractionated atmospheric isotope composition. In many applications of aquatic systems molecular diffusion was thought to cause a mass dependent fractionation of noble gases and their isotopes according to the square root ratio of their masses. However, recent experiments focusing on isotopic fractionation within a single element challenged this broadly accepted assumption. The determined fractionation factors of Ne, Ar, Kr and Xe isotopes revealed that only Ar follows the prediction of the so-called square root relation, whereas within the Ne, Kr and Xe elements no mass-dependence was found. The reason for this unexpected divergence of Ar is not yet understood. The aim of our computational exercise is to establish the molecular-resolved mechanisms behind molecular diffusion of noble gases in water. We make the hypothesis that weak intermolecular interactions are relevant for the dynamical properties of noble gases dissolved in water. Therefore, we used ab initio molecular dynamics to explicitly account for the electronic degrees of freedom. Depending on the size and polarizability of the hydrophobic particles such as noble gases, their motion in dense and polar liquids like water is subject to different diffusive regimes: the inter-cavity hopping mechanism of small particles (He, Ne) breaks down if a critical particle size achieved. For the case of large particles (Kr, Xe), the motion through the water solvent is governed by mass-independent viscous friction leading to hydrodynamical diffusion. Finally, Ar falls in between the two diffusive regimes, where particle dispersion is propagated at the molecular collision time scale of the surrounding water molecules.

  16. Study of temperature distribution in a Stirling engine regenerator

    International Nuclear Information System (INIS)

    Gheith, R.; Aloui, F.; Ben Nasrallah, S.

    2014-01-01

    Highlights: • A Gamma-Stirling engine is experimented to determine the optimal operation parameters. • A set of experiment reveals a difference of temperature between regenerator sides. • A phenomenon which consumes a part of the produced energy by the engine is highlighted. • A multi-objectif study based on experimental design methodology is developed. • The optimal set of operation parameters maximizing the engine power is proposed. - Abstract: A gamma Stirling engine is studied in this paper. A special care was accorded to the instrumentation of this engine and especially the instrumentation of the regenerator. A preliminarily set of experimental measurement reveals a difference of temperature between both regenerator sides. A second set of experiments was proposed to detect the influence of this phenomenon on Stirling engine performances. The asymmetry of heat transfer inside the Stirling engine regenerator’s is one of the important phenomenons which consume a part of the produced energy. Two experiments are made to find out the causes of this asymmetry. In order to know the influence of the different operation parameters on this new phenomenon the experimental design method is adopted. The experimental design is an alternative to identify the parameters sets allowing optimal Stirling engine performances. A central composite rotatable design was adopted for minimizing the asymmetry of temperature between both regenerator sides and maximizes the engine brake power. The selected four independent parameters are: heating temperature (300 °C–500 °C), initial filling pressure (3 bar–8 bar), cooling water flow rate (0.2 l/m–3 l/min) and operation time (4–20 min after study regime). The four adopted factors are experimentally varied. The results show that the heating temperature is the most significant factor for the studied phenomenon. The major damages caused by this phenomenon will be presented too

  17. Liquid air fueled open–closed cycle Stirling engine

    International Nuclear Information System (INIS)

    Xu, Weiqing; Wang, Jia; Cai, Maolin; Shi, Yan

    2015-01-01

    Highlights: • Energy of liquid air is divided into cryogenic energy and expansion energy. • Open–closed cycle Stirling mechanism is employed to improve efficiency. • The Schmidt theory is modified to describe temperature variation in cold space. - Abstract: An unconventional Stirling engine is proposed and its theoretical analysis is performed. The engine belongs to a “cryogenic heat engine” that is fueled by cryogenic medium. Conventional “cryogenic heat engine” employs liquid air as pressure source, but disregards its heat-absorbing ability. Therefore, its efficiency can only be improved by increasing vapor pressure, accordingly increasing the demand on pressure resistance and sealing. In the proposed engine, the added Stirling mechanism helps achieve its high efficiency and simplicity by utilizing the heat-absorbing ability of liquid air. On one hand, based on Stirling mechanism, gas in the hot space absorbs heat from atmosphere when expanding; gas in the cold space is cooled down by liquid air when compressed. Taking atmosphere as heat source and liquid air as heat sink, a closed Stirling cycle is formed. On the other hand, an exhaust port is set in the hot space. When expanding in the hot space, the vaporized gas is discharged through the exhaust port. Thus, an open cycle is established. To model and analyze the system, the Schmidt theory is modified to describe temperature variation in the cold space, and irreversible characteristic of regenerator is incorporated in the thermodynamic model. The results obtained from the model show that under the same working pressure, the efficiency of the proposed engine is potentially higher than that of conventional ones and to achieve the same efficiency, the working pressure could be lower with the new mechanism. Its efficiency could be improved by reducing temperature difference between the regenerator and the cold/hot space, increasing the swept volume ratio, decreasing the liquid–gas ratio. To keep

  18. Free-piston Stirling engine conceptual design and technologies for space power, Phase 1. Final Report

    International Nuclear Information System (INIS)

    Penswick, L.B.; Beale, W.T.; Wood, J.G.

    1990-01-01

    As part of the SP-100 program, a phase 1 effort to design a free-piston Stirling engine (FPSE) for a space dynamic power conversion system was completed. SP-100 is a combined DOD/DOE/NASA program to develop nuclear power for space. This work was completed in the initial phases of the SP-100 program prior to the power conversion concept selection for the Ground Engineering System (GES). Stirling engine technology development as a growth option for SP-100 is continuing after this phase 1 effort. Following a review of various engine concepts, a single-cylinder engine with a linear alternator was selected for the remainder of the study. The relationships of specific mass and efficiency versus temperature ratio were determined for a power output of 25 kWe. This parametric study was done for a temperature ratio range of 1.5 to 2.0 and for hot-end temperatures of 875 K and 1075 K. A conceptual design of a 1080 K FPSE with a linear alternator producing 25 kWe output was completed. This was a single-cylinder engine designed for a 62,000 hour life and a temperature ratio of 2.0. The heat transport systems were pumped liquid-metal loops on both the hot and cold ends. These specifications were selected to match the SP-100 power system designs that were being evaluated at that time. The hot end of the engine used both refractory and superalloy materials; the hot-end pressure vessel featured an insulated design that allowed use of the superalloy material. The design was supported by the hardware demonstration of two of the component concepts - the hydrodynamic gas bearing for the displacer and the dynamic balance system. The hydrodynamic gas bearing was demonstrated on a test rig. The dynamic balance system was tested on the 1 kW RE-1000 engine at NASA Lewis

  19. A novel active free piston Stirling engine: Modeling, development, and experiment

    International Nuclear Information System (INIS)

    Tavakolpour-Saleh, A.R.; Zare, SH.; Bahreman, H.

    2017-01-01

    Highlights: •A novel active free piston Stirling engine is modeled, fabricated, and tested. •A dynamic model of the engine is presented and experimentally validated. •A systematic way to find gas temperature within the hot and cold spaces is proposed. •The simulated thermal efficiency of 19.4% proves the potential of the concept. -- Abstract: This paper focuses on mathematical modeling, development, and experimental evaluation of a novel active free piston Stirling engine (AFPSE). First, working principles of the proposed AFPSE are described and its advantages are introduced. Then, a comprehensive mathematical model of the proposed Mechatronic system is presented using kinematic, dynamic, thermodynamic, heat transfer, and electrical equations. The Schmidt’s theory assumptions are used throughout the modeling scheme except for finite heat transfer and imperfect regeneration. Next, a systematic way to estimate the gas temperature in the expansion and compression spaces of the engine is presented taking into account the imperfect regeneration and finite heat transfer in the presented converter. Moreover, the engine performance, as well as the resonant frequency of the active converter, is investigated through simulation. Finally, the proposed AFPSE is developed and primarily tested. The obtained practical results clearly demonstrate the feasibility of generating power (i.e. 7.1 W) through thermal excitation of a one degree-of-freedom (1-DOF) dynamic system with its resonant frequency (i.e. 9.2 Hz). Furthermore, it is found that the experimental measurements are in an acceptable agreement with the simulation outcomes of the analytical model through which validity of the mathematical scheme is affirmed.

  20. Free-piston Stirling engine conceptual design and technologies for space power, phase 1

    Science.gov (United States)

    Penswick, L. Barry; Beale, William T.; Wood, J. Gary

    1990-01-01

    As part of the SP-100 program, a phase 1 effort to design a free-piston Stirling engine (FPSE) for a space dynamic power conversion system was completed. SP-100 is a combined DOD/DOE/NASA program to develop nuclear power for space. This work was completed in the initial phases of the SP-100 program prior to the power conversion concept selection for the Ground Engineering System (GES). Stirling engine technology development as a growth option for SP-100 is continuing after this phase 1 effort. Following a review of various engine concepts, a single-cylinder engine with a linear alternator was selected for the remainder of the study. The relationships of specific mass and efficiency versus temperature ratio were determined for a power output of 25 kWe. This parametric study was done for a temperature ratio range of 1.5 to 2.0 and for hot-end temperatures of 875 K and 1075 K. A conceptual design of a 1080 K FPSE with a linear alternator producing 25 kWe output was completed. This was a single-cylinder engine designed for a 62,000 hour life and a temperature ratio of 2.0. The heat transport systems were pumped liquid-metal loops on both the hot and cold ends. These specifications were selected to match the SP-100 power system designs that were being evaluated at that time. The hot end of the engine used both refractory and superalloy materials; the hot-end pressure vessel featured an insulated design that allowed use of the superalloy material. The design was supported by the hardware demonstration of two of the component concepts - the hydrodynamic gas bearing for the displacer and the dynamic balance system. The hydrodynamic gas bearing was demonstrated on a test rig. The dynamic balance system was tested on the 1 kW RE-1000 engine at NASA Lewis.

  1. Stirling Convertor Performance Mapping Test Results for Future Radioisotope Power Systems

    Science.gov (United States)

    Qiu, Songgang; Peterson, Allen A.; Faultersack, Franklyn D.; Redinger, Darin L.; Augenblick, John E.

    2004-02-01

    Long-life radioisotope-fueled generators based on free-piston Stirling convertors are an energy-conversion solution for future space applications. The high efficiency of Stirling machines makes them more attractive than the thermoelectric generators currently used in space. Stirling Technology Company (STC) has been performance-testing its Stirling generators to provide data for potential system integration contractors. This paper describes the most recent test results from the STC RemoteGen™ 55 W-class Stirling generators (RG-55). Comparisons are made between the new data and previous Stirling thermodynamic simulation models. Performance-mapping tests are presented including variations in: internal charge pressure, cold end temperature, hot end temperature, alternator temperature, input power, and variation of control voltage.

  2. Soil carbon dynamics inferred from carbon isotope compositions of soil organic matter and soil respiration

    International Nuclear Information System (INIS)

    Koarashi, Jun; Asano, Tomohiro; Iida, Takao; Moriizumi, Jun

    2004-01-01

    To better understand 14 C cycling in terrestrial ecosystems, 14 C abundances were evaluated for fractionated soil organic matter (SOM) and soil respiration in an urban forest. In 2001 soil profile, Δ 14 C values of litter and bulk SOM increased rapidly from litter surface (62.7 per mille) to uppermost mineral soil layer (244.9 per mille), and then decreased sharply to 6 cm depth of mineral soil (125.0 per mille). Carbon enriched in 14 C by atmospheric nuclear weapons testing had penetrated to at least 16 cm depth of mineral soil. The average Δ 14 C in atmospheric CO 2 was 58.8 per mille in August 2001, suggesting recent carbon input to the topmost litter layer. Although a similar depth distribution was observed for Δ 14 C values of residual SOM after acid hydrolysis, the Δ 14 C values were slightly lower than those in bulk SOM. This indicates input of 'bomb' C into this organic fraction and higher 14 C abundance in acid-soluble SOM. The most of CO 2 may be derived from the microbial decomposition of the acid-soluble, or labile, SOM. Therefore, the labile SOM may become most influential pool for soil carbon cycling. In contrast, carbon in base-insoluble SOM remained considerably low in 14 C abundance at all depths, suggesting no or little incorporation of 'bomb' C to this fraction. Values of Δ 14 C in soil respiration ranged from 91.9 to 146.4 per mille in August 2001, showing a significant contribution from decomposition of SOM fixed over past 2-40 years. These results indicate that the use of bulk SOM as a representative of soil carbon pool would lead to severe misunderstand of the soil C dynamics on decadal and shorter time scales. (author)

  3. Recovery of Exhaust Waste Heat for ICE Using the Beta Type Stirling Engine

    OpenAIRE

    Aladayleh, Wail; Alahmer, Ali

    2015-01-01

    This paper investigates the potential of utilizing the exhaust waste heat using an integrated mechanical device with internal combustion engine for the automobiles to increase the fuel economy, the useful power, and the environment safety. One of the ways of utilizing waste heat is to use a Stirling engine. A Stirling engine requires only an external heat source as wasted heat for its operation. Because the exhaust gas temperature may reach 200 to 700°C, Stirling engine will work effectively....

  4. Overview of heat transfer and fluid flow problem areas encountered in Stirling engine modeling

    Science.gov (United States)

    Tew, Roy C., Jr.

    1988-01-01

    NASA Lewis Research Center has been managing Stirling engine development programs for over a decade. In addition to contractual programs, this work has included in-house engine testing and development of engine computer models. Attempts to validate Stirling engine computer models with test data have demonstrated that engine thermodynamic losses need better characterization. Various Stirling engine thermodynamic losses and efforts that are underway to characterize these losses are discussed.

  5. Trophic Dynamics of Filter Feeding Bivalves in the Yangtze Estuarine Intertidal Marsh: Stable Isotope and Fatty Acid Analyses

    Science.gov (United States)

    Wang, Sikai; Jin, Binsong; Qin, Haiming; Sheng, Qiang; Wu, Jihua

    2015-01-01

    Benthic bivalves are important links between primary production and consumers, and are essential intermediates in the flow of energy through estuarine systems. However, information on the diet of filter feeding bivalves in estuarine ecosystems is uncertain, as estuarine waters contain particulate matter from a range of sources and as bivalves are opportunistic feeders. We surveyed bivalves at different distances from the creek mouth at the Yangtze estuarine marsh in winter and summer, and analyzed trophic dynamics using stable isotope (SI) and fatty acid (FA) techniques. Different bivalve species had different spatial distributions in the estuary. Glauconome chinensis mainly occurred in marshes near the creek mouth, while Sinonovacula constricta preferred the creek. Differences were found in the diets of different species. S. constricta consumed more diatoms and bacteria than G. chinensis, while G. chinensis assimilated more macrophyte material. FA markers showed that plants contributed the most (38.86 ± 4.25%) to particular organic matter (POM) in summer, while diatoms contributed the most (12.68 ± 1.17%) during winter. Diatoms made the largest contribution to the diet of S. constricta in both summer (24.73 ± 0.44%) and winter (25.51 ± 0.59%), and plants contributed no more than 4%. This inconsistency indicates seasonal changes in food availability and the active feeding habits of the bivalve. Similar FA profiles for S. constricta indicated that the bivalve had a similar diet composition at different sites, while different δ13C results suggested the diet was derived from different carbon sources (C4 plant Spartina alterniflora and C3 plant Phragmites australis and Scirpus mariqueter) at different sites. Species-specific and temporal and/or spatial variability in bivalve feeding may affect their ecological functions in intertidal marshes, which should be considered in the study of food webs and material flows in estuarine ecosystems. PMID:26261984

  6. Isotopic effects in vibrational relaxation dynamics of H on a Si(100) surface

    Science.gov (United States)

    Bouakline, F.; Lorenz, U.; Melani, G.; Paramonov, G. K.; Saalfrank, P.

    2017-10-01

    a net exponential decay of the time-dependent survival probability for the H-Si initial vibrational state, allowing an easy extraction of the bending mode "lifetime." This is in contrast with the D-Si system, whose survival probability exhibits a non-monotonic decay, making it difficult to define such a lifetime. This different behavior of the vibrational decay is rationalized in terms of the power spectrum of the adsorbate-surface system. In the case of D-Si, it consists of several, non-uniformly distributed peaks around the bending mode frequency, whereas the H-Si spectrum exhibits a single Lorentzian lineshape, whose width corresponds to the calculated lifetime. The present work gives some insight into mechanisms of vibration-phonon coupling at surfaces. It also serves as a benchmark for multidimensional system-bath quantum dynamics, for comparison with approximate schemes such as reduced, open-system density matrix theory (where the bath is traced out and a Liouville-von Neumann equation is solved) or approximate wavefunction methods to solve the combined system-bath Schrödinger equation.

  7. Thermodynamic analysis and experimental investigation of a Solo V161 Stirling cogeneration unit

    International Nuclear Information System (INIS)

    Rogdakis, E.D.; Antonakos, G.D.; Koronaki, I.P.

    2012-01-01

    In order to investigate the Stirling engine implementation technology, a Solo Stirling Engine V161 cogeneration module has been installed at the Laboratory of Applied Thermodynamics of National Technical University of Athens. A special thermodynamic analysis of the engine's performance has been conducted introducing and utilizing specially designed computing codes along with the thermal balance study of the unit. Measurements were conducted under different operational conditions concerning various heat load stages of the engine, working pressure, as well as electric power production. Analysis of the experimental results has shown that the overall performance of the Stirling unit proved very promising and quite adequate for various areal applications, equally competing with other CHP systems. The performance of the unit experienced significant stability all over the operating range. The power stand ratio 0.35 differentiates Stirling cogeneration units from others that use diverging technologies significantly. The energy savings using a Stirling CHP unit, in respect to the concurrent use of a thermal and an electrical system at the same equivalent power has revealed 36.8%. -- Highlights: ► Thermodynamic analysis of an a-type Stirling engine. ► Development of generated electrical and thermal power of the m-CHP Solo Stirling Unit to engine's load comparison. ► Stirling m-CHP until heat balance analysis. ► Evaluation of the Solo Stirling V161 unit efficiency.

  8. Thermodynamic analysis of SOFC (solid oxide fuel cell) - Stirling hybrid plants using alternative fuels

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2013-01-01

    A novel hybrid power system (∼10 kW) for an average family home is proposed. The system investigated contains a solid oxide fuel cell (SOFC) on top of a Stirling engine. The off-gases produced in the SOFC cycle are fed to a bottoming Stirling engine, at which additional power is generated...... to that of a stand-alone Stirling engine or SOFC plant. For the combined SOFC and Stirling configuration, the overall power production was increased by approximately 10% compared to that of a stand-alone SOFC plant. System efficiencies of approximately 60% are achieved, which is remarkable for such small plant sizes...

  9. Plant Characteristics af a Multi-Fuel Sofc-Stirling Hybrid Configuration

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2012-01-01

    A novel hybrid system ( kWe) for an average family house including heating is proposed. The system investigated, contains of a Solid Oxide Fuel Cell (SOFC) on top of a Stirling engine. The off-gases produced in the SOFC cycle is fed to the bottoming Stirling engine wherein additional power...... efficiency compared with the stand alone Stirling engine or SOFC plant. For the SOFC and Stirling combined configuration, the overall power production has increased by about 10% compared to the stand alone SOFC plant. System efficiencies of about 60% are achieved which is remarkable for such small plant...

  10. Performance Analysis and Optimization of a Solar Powered Stirling Engine with Heat Transfer Considerations

    Directory of Open Access Journals (Sweden)

    Chia-En Ho

    2012-09-01

    Full Text Available This paper investigates the optimization of the performance of a solar powered Stirling engine based on finite-time thermodynamics. Heat transference in the heat exchangers between a concentrating solar collector and the Stirling engine is studied. The irreversibility of a Stirling engine is considered with the heat transfer following Newton's law. The power generated by a Stirling engine is used as an objective function for maximum power output design with the concentrating solar collector temperature and the engine thermal efficiency as the optimization parameters. The maximum output power of engine and its corresponding system parameters are determined using a genetic algorithm.

  11. Innovative Stirling Convertor for Distributed Electric Power from Thermal Energy Recovery, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — SCCAQ Energy, LLC (SCCAQ) in collaboration with Temple University and Infinia Technology Corporation (ITC) proposes to develop a Reliable Stirling Convertor (RSC)...

  12. Optimal laser control of molecular wave packet dynamics under the influence of dissipation: possibility of isotope separation

    International Nuclear Information System (INIS)

    Ohtsuki, Yukiyoshi

    2004-01-01

    Possibility of fs-laser-pulse isotope separation is numerically investigated using optimal control theory. Optimal pulses that separate the 1:1 mixture of 79 Br 2 and 28 1 Br 2 are calculated. Quantum interferences induced by the optimally designed fs pulse efficiently enhance the isotope shifts through multiple electronic transitions, which results in a high enrichment factor. When utilizing vibrational multi-photon transitions (a virtual model), an optimal pulse can transfer the two isotopes to specified different vibrational states with almost 100% probability. In the presence of colored noises, the optimal pulse achieves the control with minimum loss of product yields within the bath correlation time. (author)

  13. Using stable isotopes to assess surface water source dynamics and hydrological connectivity in a high-latitude wetland and permafrost influenced landscape

    Science.gov (United States)

    Ala-aho, P.; Soulsby, C.; Pokrovsky, O. S.; Kirpotin, S. N.; Karlsson, J.; Serikova, S.; Vorobyev, S. N.; Manasypov, R. M.; Loiko, S.; Tetzlaff, D.

    2018-01-01

    Climate change is expected to alter hydrological and biogeochemical processes in high-latitude inland waters. A critical question for understanding contemporary and future responses to environmental change is how the spatio-temporal dynamics of runoff generation processes will be affected. We sampled stable water isotopes in soils, lakes and rivers on an unprecedented spatio-temporal scale along a 1700 km transect over three years in the Western Siberia Lowlands. Our findings suggest that snowmelt mixes with, and displaces, large volumes of water stored in the organic soils and lakes to generate runoff during the thaw season. Furthermore, we saw a persistent hydrological connection between water bodies and the landscape across permafrost regions. Our findings help to bridge the understanding between small and large scale hydrological studies in high-latitude systems. These isotope data provide a means to conceptualise hydrological connectivity in permafrost and wetland influenced regions, which is needed for an improved understanding of future biogeochemical changes.

  14. Phosphorus dynamics in soils irrigated with reclaimed waste water or fresh water - A study using oxygen isotopic composition of phosphate

    Science.gov (United States)

    Zohar, I.; Shaviv, A.; Young, M.; Kendall, C.; Silva, S.; Paytan, A.

    2010-01-01

    Transformations of phosphate (Pi) in different soil fractions were tracked using the stable isotopic composition of oxygen in phosphate (??18Op) and Pi concentrations. Clay soil from Israel was treated with either reclaimed waste water (secondary, low grade) or with fresh water amended with a chemical fertilizer of a known isotopic signature. Changes of ??18Op and Pi within different soil fractions, during a month of incubation, elucidate biogeochemical processes in the soil, revealing the biological and the chemical transformation impacting the various P pools. P in the soil solution is affected primarily by enzymatic activity that yields isotopic equilibrium with the water molecules in the soil solution. The dissolved P interacts rapidly with the loosely bound P (extracted by bicarbonate). The oxides and mineral P fractions (extracted by NaOH and HCl, respectively), which are considered as relatively stable pools of P, also exhibited isotopic alterations in the first two weeks after P application, likely related to the activity of microbial populations associated with soil surfaces. Specifically, isotopic depletion which could result from organic P mineralization was followed by isotopic enrichment which could result from preferential biological uptake of depleted P from the mineralized pool. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with reclaimed waste water compared to the fertilizer treated soil. ?? 2010 Elsevier B.V.

  15. Stirling cryocooler test results and design model verification

    International Nuclear Information System (INIS)

    Shimko, M.A.; Stacy, W.D.; McCormick, J.A.

    1990-01-01

    This paper reports on progress in developing a long-life Stirling cycle cryocooler for space borne applications. It presents the results from tests on a preliminary breadboard version of the cryocooler used to demonstrate the feasibility of the technology and to validate the regenerator design code used in its development. This machine achieved a cold-end temperature of 65 K while carrying a 1/2 Watt cooling load. The basic machine is a double-acting, flexure-bearing, split Stirling design with linear electromagnetic drives for the expander and compressors. Flat metal diaphragms replace pistons for both sweeping and sealing the machine working volumes. In addition, the double-acting expander couples to a laminar-channel counterflow recuperative heat exchanger for regeneration. A PC compatible design code was developed for this design approach that calculates regenerator loss including heat transfer irreversibilities, pressure drop, and axial conduction in the regenerator walls

  16. Optimal power and efficiency of quantum Stirling heat engines

    Science.gov (United States)

    Yin, Yong; Chen, Lingen; Wu, Feng

    2017-01-01

    A quantum Stirling heat engine model is established in this paper in which imperfect regeneration and heat leakage are considered. A single particle which contained in a one-dimensional infinite potential well is studied, and the system consists of countless replicas. Each particle is confined in its own potential well, whose occupation probabilities can be expressed by the thermal equilibrium Gibbs distributions. Based on the Schrödinger equation, the expressions of power output and efficiency for the engine are obtained. Effects of imperfect regeneration and heat leakage on the optimal performance are discussed. The optimal performance region and the optimal values of important parameters of the engine cycle are obtained. The results obtained can provide some guidelines for the design of a quantum Stirling heat engine.

  17. Thermodynamic analysis of a Stirling engine including regenerator dead volume

    Energy Technology Data Exchange (ETDEWEB)

    Puech, Pascal; Tishkova, Victoria [Universite de Toulouse, UPS, CNRS, CEMES, 29 rue Jeanne Marvig, F-31055 Toulouse (France)

    2011-02-15

    This paper provides a theoretical investigation on the thermodynamic analysis of a Stirling engine with linear and sinusoidal variations of the volume. The regenerator in a Stirling engine is an internal heat exchanger allowing to reach high efficiency. We used an isothermal model to analyse the net work and the heat stored in the regenerator during a complete cycle. We show that the engine efficiency with perfect regeneration doesn't depend on the regenerator dead volume but this dead volume strongly amplifies the imperfect regeneration effect. An analytical expression to estimate the improvement due to the regenerator has been proposed including the combined effects of dead volume and imperfect regeneration. This could be used at the very preliminary stage of the engine design process. (author)

  18. A parametric investigation on a solar dish-Stirling system

    Science.gov (United States)

    Gholamalizadeh, Ehsan; Chung, Jae Dong

    2018-06-01

    The aim of this study is to analyze the performance of a solar dish-Stirling system. A mathematical model for the overall thermal efficiency of the solar-powered high-temperature-differential dish-Stirling engine is described. This model takes into account pressure losses due to fluid friction which is internal to the engine, mechanical friction between the moving parts, actual heat transfer includes the effects of both internal and external irreversibilities of the cycle and finite regeneration processes time. Validation was done through comparison with the actual power output of the "EuroDish" system. Moreover, the effects of dish diameter and working fluid on the performance of the system were studied. An increase of about 7.2% was observed for the power output using hydrogen as the working fluid rather than helium. Also, the focal distance for any diameter of dish was calculated.

  19. Thermal energy storage for the Stirling engine powered automobile

    Science.gov (United States)

    Morgan, D. T. (Editor)

    1979-01-01

    A thermal energy storage (TES) system developed for use with the Stirling engine as an automotive power system has gravimetric and volumetric storage densities which are competitive with electric battery storage systems, meets all operational requirements for a practical vehicle, and can be packaged in compact sized automobiles with minimum impact on passenger and freight volume. The TES/Stirling system is the only storage approach for direct use of combustion heat from fuel sources not suitable for direct transport and use on the vehicle. The particular concept described is also useful for a dual mode TES/liquid fuel system in which the TES (recharged from an external energy source) is used for short duration trips (approximately 10 miles or less) and liquid fuel carried on board the vehicle used for long duration trips. The dual mode approach offers the potential of 50 percent savings in the consumption of premium liquid fuels for automotive propulsion in the United States.

  20. Mechanically-cooled germanium detector using two stirling refrigerators

    International Nuclear Information System (INIS)

    Katagiri, Masaki; Kobayashi, Yoshii; Takahashi, Koji

    1996-01-01

    In this paper, we present a developed mechanically-cooled germanium gamma-ray detector using Stirling refrigerators. Two Stirling refrigerators having cooling faculty of 1.5W at 80K were used to cool down a germanium detector element to 77K instead of a dewar containing liquid nitrogen. An 145cm 3 (56.0mmf x 59.1 mml) closed-end Ge(I) detector having relative detection efficiency of 29.4% was attached at the refrigerators. The size of the detector was 60cml x 15cmh x 15cmw. The lowest cooling temperature, 70K was obtained after 8 hours operation. The energy resolutions for 1.33MeV gamma-rays and for pulser signals were 2.43keV and 1.84keV at an amplifier shaping time of 2μsec, respectively

  1. Optimization design and performance analysis of a miniature stirling engine

    Science.gov (United States)

    You, Zhanping; Yang, Bo; Pan, Lisheng; Hao, Changsheng

    2017-10-01

    Under given operation conditions, a stirling engine of 2 kW is designed which takes hydrogen as working medium. Through establishment of adiabatic model, the ways are achieved about performance improving. The ways are raising the temperature of hot terminal, lowering the temperature of cold end, increasing the average cycle pressure, speeding up the speed, phase angle being 90°, stroke volume ratio approximating to 1 and increasing the performance of regenerator.

  2. Split-Stirling Cryogenic Refrigerators For Detector Cooling

    Science.gov (United States)

    Lehrfeld, Daniel

    1983-08-01

    Unfortunately, for user and manufacturer both, the closed-cycle cryogenic cooler to date has deserved its reputation as the "weak-link" in IR systems. When the cooler requires service at intervals of a few hundred hours at best, the quality of the system it serves is unfairly diminished. This paper addresses technological advances in the art of Stirling-cycle coolers which will increasingly cause that image of military cryocoolers to change for the better. A family of split-cycle coolers designed for long MTBF and in the final stages of development is the focus of the discussion. Their technological evolution, from multi-year-MTBF satellite system Stirling coolers developed in the U.S., and the UA 7011 cooler (tne first all-linear, military, production cooler) developed in Holland, is explained. Three new machines are discussed. Both 1/4 watt and 1 watt (nominal capacity) at 80°K linear-resonant, free-dispLacer Stirling coolers designed for thousands of hours of service-free operation are examined. The third machine is an advanced 1/4 watt at 80°K Stirling cooler incorporating the same component improvements in its free-displacer while utilizing a crankshaft-driven compressor. All three are designed to be compatible with standard U.S. 60 element and 120/180 element detector/dewars. The technologies of linear-resonant compressor and free-displacer expanders as embodied in these machines is discussed in sufficient detail that the reasons for their superior performance will he clear.

  3. Optimization of Stirling and Ericsson cycles by solar radiation

    Science.gov (United States)

    Badescu, V.

    This paper considers a model consisting of a source of radiation (the sun) and two energy converters. The first converter (the absorber) transforms the solar radiation into heat while the second one (which is a Stirling or Ericsson engine) uses heat to produce mechanical work. Polarization coefficients were introduced to characterize the radiation emitted by two components of the system (the sun and the first converter). The maximum conversion efficiency of solar radiation into work was studied.

  4. Linear motor driven Stirling coolers for military and commercial applications

    International Nuclear Information System (INIS)

    Berry, R.

    1992-01-01

    This paper discusses the design and performance of a miniature, closed cycle, split stirling, cryogenic cooler that provides 1 watt of cooling at 80 K. The compressor uses two opposed linear motors to drive opposed pistons and the expander uses a pneumatically driven displacer. A single electronics module and compressor has been developed to drive three different expanders that have nominal cold cylinder diameters of 5, 8 and 13 mm

  5. A Stirling engine analysis method based upon moving gas nodes

    Science.gov (United States)

    Martini, W. R.

    1986-01-01

    A Lagrangian nodal analysis method for Stirling engines (SEs) is described, validated, and applied to a conventional SE and an isothermalized SE (with fins in the hot and cold spaces). The analysis employs a constant-mass gas node (which moves with respect to the solid nodes during each time step) instead of the fixed gas nodes of Eulerian analysis. The isothermalized SE is found to have efficiency only slightly greater than that of a conventional SE.

  6. The study, design and simulation of a free piston Stirling engine linear alternatorThe study, design and simulation of a free piston Stirling engine linear alternator

    Directory of Open Access Journals (Sweden)

    Teodora Susana Oros

    2014-12-01

    Full Text Available This paper presents a study, design and simulation of a Free Piston Stirling Engine Linear Alternator. There are presented the main steps of the magnetic and electric calculations for a permanent magnet linear alternator of fixed coil and moving magnets type. Finally, a detailed thermal, mechanical and electrical model for a Stirling engine linear alternator have been made in SIMULINK simulation program. The linear alternator simulation model uses a controllable DC voltage which simulates the linear alternator combined with a rectifier, a variable load and a DC-DC converter, which compensates for the variable nature of Stirling engine operation, and ensures a constant voltage output regardless of the load.

  7. Hybrid heat recovery - flat plate Stirling engine system

    International Nuclear Information System (INIS)

    Bogdanizh, A.M.; Budin, R.; Sutlovizh, I.

    2000-01-01

    In this paper, the possibility of process condensate heat recovery for boiler water preheating as well as for combined heat and power production for chosen process in textile industry has been investigated. The garment industry requires low pressure process steam or hot water for which production expensive fossil fuel should be used. Fuel usage can be reduced by various energy conservation methods. During the process a great quantity of hot condensate or waste hot water is rejected in the sewage system. To reduce heat wastes and improve technological process this condensate could be returned to the boiler for feed water preheating. When 60% condensate is returned to the steam generator about 8 % natural gas is saved. The rest of the condensate should be used for driving low temperature flat plate Stirling motor the advantage of the flat plate Stirling engine is ability to work at low temperatures. This engine produces electrical energy which can put in motion an electrogenerator in the same plant. While Stirling engine can be used electrical power and economical effect could be much greater using such a hybrid system the process waste heat is not only converted into useful work but at the same time thermal pollution is greatly diminished. (Author)

  8. Characterization of the Advanced Stirling Radioisotope Generator EU2

    Science.gov (United States)

    Lewandowski, Edward J.; Oriti, Salvatore M.; Schifer, Nicholas A.

    2015-01-01

    Significant progress was made developing the Advanced Stirling Radioisotope Generator (ASRG), a 140-watt radioisotope power system. While the ASRG flight development project has ended, the hardware that was designed and built under the project is continuing to be tested to support future Stirling-based power system development. NASA GRC recently completed the assembly of the ASRG Engineering Unit 2 (EU2). The ASRG EU2 consists of the first pair of Sunpower's ASC-E3 Stirling convertors mounted in an aluminum housing, and Lockheed Martin's Engineering Development Unit (EDU) 4 controller (a fourth generation controller). The ASC-E3 convertors and Generator Housing Assembly (GHA) closely match the intended ASRG Qualification Unit flight design. A series of tests were conducted to characterize the EU2, its controller, and the convertors in the flight-like GHA. The GHA contained an argon cover gas for these tests. The tests included: measurement of convertor, controller, and generator performance and efficiency, quantification of control authority of the controller, disturbance force measurement with varying piston phase and piston amplitude, and measurement of the effect of spacecraft DC bus voltage on EU2 performance. The results of these tests are discussed and summarized, providing a basic understanding of EU2 characteristics and the performance and capability of the EDU 4 controller.

  9. A free-piston Stirling cryocooler using metal diaphragms

    Science.gov (United States)

    Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

    2016-12-01

    A novel concept for a free-piston Stirling cryocooler has been proposed. The concept uses a pair of metal diaphragms to seal and suspend the displacer of a free-piston Stirling cryocooler. The diaphragms allow the displacer to move without rubbing or moving seals, potentially resulting in a long-life mechanism. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicates the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. Sage predicted the macroscopic behaviour of the prototype well but did not provide sufficient insights to improve performance significantly. This paper presents details of the development, modelling and testing of the proof-of-concept prototype and a second, improved prototype.

  10. Status of NASA's Stirling Space Power Converter Program

    International Nuclear Information System (INIS)

    Dudenhoefer, J.E.; Winter, J.M.

    1994-01-01

    An overview is presented of the NASA Lewis Research Center Free-Piston Stirling Space Power Converter Technology Program. This work is being conducted under NASA's Civil Space Technology Initiative. The goal of the CSTI High Capacity Power Element is to develop the technology base needed to meet the long duration, high capacity power requirements for future NASA space initiatives. Efforts are focused upon increasing system power output and system thermal and electric energy conversion efficiency at least fivefold over current SP-100 technology, and on achieving systems that are compatible with space nuclear reactors. This paper will discuss Stirling experience in Space Power Converters. Fabrication is nearly completed for the 1050 K Component Test Power Converter (CTPC); results of motoring tests of the cold end (525 K), are presented. The success of these and future designs is dependent upon supporting research and technology efforts including heat pipes, bearings, superalloy joining technologies, high efficiency alternators, life and reliability testing and predictive methodologies. This paper provides an update of progress in some of these technologies leading off with a discussion of free-piston Stirling experience in space

  11. Parametric study on beta-type Stirling engine

    International Nuclear Information System (INIS)

    Abuelyamen, A.; Ben-Mansour, R.; Abualhamayel, H.; Mokheimer, Esmail M.A.

    2017-01-01

    Highlights: • A parametric study of laminar flow for a β-type Stirling engine was performed. • The optimum charge pressure varies from gas to another. • Stirling engine runs better below the optimum charge pressure for H 2 and He. • Power output increases with temperature while thermal efficiency decreases. • For air and He, output power increases with temperature differences (T H − T C ). - Abstract: In this work, a parametric study on a β-type Stirling engine with no regenerator was conducted numerically using ANSYS fluent 14.5 software. The three parameters that were studied are; initial charge pressure, thermal boundary condition; and three different types of working fluids (Air, He and H 2 ). Variable thermal properties of these gases were adopted to get more realistic results. The results include a comparison of the amount of heat transfer, power output, and thermal efficiency. It was found that the best engine performance is achieved when H 2 gas is used as working fluid. Moreover, results revealed that each of the power output and the efficiency has different optimum charge pressure. Additionally, it was found that there is a small variation in the pressure across the engine chambers, which results in miss matching between the net heat transfer rates and power output calculated from PV-diagram. This error is higher when the air is used as working fluid, especially at high charge pressure.

  12. Feasibility study of dish/stirling power systems in Turkey

    Science.gov (United States)

    Zilanlı, Gülin Acarol; Eray, Aynur

    2017-06-01

    In this study, two different commercial dish/stirling systems, SES (Stirling Energy Systems) and WGA-ADDS (WGAssociates - Advanced Dish Development System), are modeled using the "System Advisor Model" (SAM) modeling software in designated settlement areas. Both systems are modeled for the US state of Albuquerque, where they were designed, and Turkish provinces of Ankara, Van, Muğla, Mersin, Urfa and Konya. At first, the dish/stirling system is optimized according to the power output values and the system loss parameters. Then, the layout of the solar field is designed with an installed capacity of 600kW both of SES and WGA-ADDS systems, Upon securing the most suitable layout, the system is modeled for the aforementioned settlements using the optimum output values gathered from the parametric analysis. As a result of the simulation studies, the applicability of this model is discussed according to the power output and the efficiency. Although Turkey is located in an area called "the sun belt" where solar energy technologies can be used, there is no advanced application of these systems. This study aims to discuss the application of these systems in detail and to pave the way for future studies in this field.

  13. Decoding the dynamics of cellular metabolism and the action of 3-bromopyruvate and 2-deoxyglucose using pulsed stable isotope-resolved metabolomics.

    Science.gov (United States)

    Pietzke, Matthias; Zasada, Christin; Mudrich, Susann; Kempa, Stefan

    2014-01-01

    Cellular metabolism is highly dynamic and continuously adjusts to the physiological program of the cell. The regulation of metabolism appears at all biological levels: (post-) transcriptional, (post-) translational, and allosteric. This regulatory information is expressed in the metabolome, but in a complex manner. To decode such complex information, new methods are needed in order to facilitate dynamic metabolic characterization at high resolution. Here, we describe pulsed stable isotope-resolved metabolomics (pSIRM) as a tool for the dynamic metabolic characterization of cellular metabolism. We have adapted gas chromatography-coupled mass spectrometric methods for metabolomic profiling and stable isotope-resolved metabolomics. In addition, we have improved robustness and reproducibility and implemented a strategy for the absolute quantification of metabolites. By way of examples, we have applied this methodology to characterize central carbon metabolism of a panel of cancer cell lines and to determine the mode of metabolic inhibition of glycolytic inhibitors in times ranging from minutes to hours. Using pSIRM, we observed that 2-deoxyglucose is a metabolic inhibitor, but does not directly act on the glycolytic cascade.

  14. Geochemistry, water dynamics and metals: Major, trace elements, Pb and Sr isotope constraints on their origins and movements in a small anthropized catchment over a flood

    International Nuclear Information System (INIS)

    Luck, J.M.; Othman, D.B.

    1997-01-01

    Major, trace elements and Sr-Pb isotope data on the dissolved and particulate phases are reported for water samples taken regularly over the September flood of a Mediterranean river (S France). This river drains runoff from a small, carbonate, karstified watershed with Miocene and Jurassic lithologies, and characterized by agricultural, urban and road network activities. The objective is to combine all the data into a dynamic model for constraining the origin(s) and movements of waters and of their loads. Furthermore, for metals, it becomes then feasible to know their fate and bioavailability downstream

  15. Preliminary Results from Simulations of Temperature Oscillations in Stirling Engine Regenerator Matrices

    DEFF Research Database (Denmark)

    Andersen, Stig Kildegård; Carlsen, Henrik; Thomsen, Per Grove

    2006-01-01

    The objective of this study has been to create a Stirling engine model for studying the effects of regenerator matrix temperature oscillations on Stirling engine performance. A one-dimensional model with axial discretisation of engine components has been formulated using the control volume method...

  16. Simulation, design and thermal analysis of a solar Stirling engine using MATLAB

    International Nuclear Information System (INIS)

    Shazly, J.H.; Hafez, A.Z.; El Shenawy, E.T.; Eteiba, M.B.

    2014-01-01

    Highlights: • Modeling and simulation for a prototype of the solar-powered Stirling engine. • The solar-powered Stirling engine working at the low temperature range. • Estimating output power from the solar Stirling engine using Matlab program. • Solar radiation simulation program presents a solar radiation data using MATLAB. - Abstract: This paper presents the modeling and simulation for a prototype of the solar-powered Stirling engine working at the low temperature range. A mathematical model for the thermal analysis of the solar-powered low temperature Stirling engine with heat transfer is developed using Matlab program. The model takes into consideration the effect of the absorber temperature on the thermal analysis like as radiation and convection heat transfer between the absorber and the working fluid as well as radiation and convection heat transfer between the lower temperature plate and the working fluid. Hence, the present analysis provides a theoretical guidance for designing and operating of the solar-powered low temperature Stirling engine system, as well as estimating output power from the solar Stirling engine using Matlab program. This study attempts to demonstrate the potential of the low temperature Stirling engine as an option for the prime movers for Photovoltaic tracking systems. The heat source temperature is 40–60 °C as the temperature available from the sun directly

  17. One-dimensional numerical simulation of the Stirling-type pulse-tube refrigerator

    NARCIS (Netherlands)

    Etaati, M.; Mattheij, R.M.M.; Tijsseling, A.S.; Waele, de A.T.A.M.

    2007-01-01

    Change of title: One-dimensional numerical simulation of the Stirling-type pulse-tube cooler. Pulse-tube refrigeration (PTR) is a new technology for cooling down to extremely low temperatures. In this paper a particular type, the so-called Stirling single-stage refrigerator, is considered. A

  18. Techno-economic assessment and optimization of stirling engine micro-cogeneration systems in residential buildings

    Energy Technology Data Exchange (ETDEWEB)

    Alanne, Kari; Soederholm, Niklas; Siren, Kai [Dept. of Energy Technology, Helsinki University of Technology, P.O. Box 4100, 02015 TKK (Finland); Beausoleil-Morrison, Ian [Dept. of Mechanical and Aerospace Engineering, Carleton University, Ottawa (Canada)

    2010-12-15

    Micro-cogeneration offers numerous potential advantages for the supply of energy to residential buildings in the sense of improved energy efficiency and reduced environmental burdens. To realize these benefits, however, such systems must reduce energy costs, primary energy consumption, and CO{sub 2} emissions relative to conventional heating systems. In this paper, we search for optimized strategies for the integration of a Stirling engine-based micro-cogeneration system in residential buildings by comparing the performance of various system configurations and operational strategies with that of a reference system, i.e. hydronic heating and a low temperature gas boiler in standard and passive house constructions located in different climates. The IDA-ICE whole-building simulation program is employed with the Stirling engine micro-cogeneration model that was developed by IEA/ECBCS Annex 42. In this way the dynamic effects of micro-cogeneration devices, such as warm-ups and shutdowns, are accounted for. This study contributes to the research by addressing hourly changes in the fuel mix used for central electricity generation and the utilization of thermal exhaust through heat recovery. Our results suggest that an optimally operated micro-cogeneration system encompassing heat recovery and appropriate thermal storage would result in a 3-5% decrease in primary energy consumption and CO{sub 2} emissions when compared to a conventional hydronic heating system. Moreover, this configuration is capable of delivering annual savings in all the combinations of electricity and fuel price between 0.05 and 0.15 EUR kW h{sup -1}. As can be expected, these results are sensitive to the electrical energy supply mix, building type, and climate. (author)

  19. Techno-economic assessment and optimization of Stirling engine micro-cogeneration systems in residential buildings

    International Nuclear Information System (INIS)

    Alanne, Kari; Soederholm, Niklas; Siren, Kai; Beausoleil-Morrison, Ian

    2010-01-01

    Micro-cogeneration offers numerous potential advantages for the supply of energy to residential buildings in the sense of improved energy efficiency and reduced environmental burdens. To realize these benefits, however, such systems must reduce energy costs, primary energy consumption, and CO 2 emissions relative to conventional heating systems. In this paper, we search for optimized strategies for the integration of a Stirling engine-based micro-cogeneration system in residential buildings by comparing the performance of various system configurations and operational strategies with that of a reference system, i.e. hydronic heating and a low temperature gas boiler in standard and passive house constructions located in different climates. The IDA-ICE whole-building simulation program is employed with the Stirling engine micro-cogeneration model that was developed by IEA/ECBCS Annex 42. In this way the dynamic effects of micro-cogeneration devices, such as warm-ups and shutdowns, are accounted for. This study contributes to the research by addressing hourly changes in the fuel mix used for central electricity generation and the utilization of thermal exhaust through heat recovery. Our results suggest that an optimally operated micro-cogeneration system encompassing heat recovery and appropriate thermal storage would result in a 3-5% decrease in primary energy consumption and CO 2 emissions when compared to a conventional hydronic heating system. Moreover, this configuration is capable of delivering annual savings in all the combinations of electricity and fuel price between 0.05 and 0.15 Euro kW h -1 . As can be expected, these results are sensitive to the electrical energy supply mix, building type, and climate.

  20. Application of computational fluid dynamics for the simulation of cryogenic molecular sieve bed absorber of hydrogen isotopes recovery system for Indian LLCB-TBM

    Energy Technology Data Exchange (ETDEWEB)

    Gayathri Devi, V.; Sircar, A.; Sarkar, B. [Institute of Plasma Research, Bhat, Gandhinagar, Gujarar (India)

    2015-03-15

    One of the most challenging tasks in the design of the fuel cycle system lies in the effective design of Tritium Extraction System (TES) which involves proper extraction and purification of tritium in the fuel cycle of the fusion reactor. Indian Lead Lithium cooled Ceramic Breeder Test Blanket Module (LLCB-TBM) would extract hydrogen isotopes through Cryogenic Molecular Sieve Bed (CMSB) adsorber system. A prototype Hydrogen Isotopes Recovery System (HIRS) is being developed to validate the concepts for tritium extraction by adsorption mass transfer mechanism. In this study, a design model has been developed and analyzed to simulate the adsorption mass transfer kinetics in a fixed bed adsorption column. The simulation leads primarily to effective design of HIRS, which is a state-of-the-art technology. The paper describes the process simulation approach and the results of Computational Fluid Dynamics (CFD) analysis. The effects of different operating conditions are studied to investigate their influence on the hydrogen isotopes adsorption capacity. The results of the present simulation study would be used to understand the best optimized transport phenomenon before realizing the TES as a system for LLCB-TBM. (authors)

  1. Development and experimental testing of a hybrid Stirling engine-adsorption chiller auxiliary power unit for heavy trucks

    International Nuclear Information System (INIS)

    Flannery, Barry; Lattin, Robert; Finckh, Oliver; Berresheim, Harald; Monaghan, Rory F.D.

    2017-01-01

    Highlights: • Free-piston Stirling engine for truck APU. • Waste heat driven adsorption chiller for cab air conditioning. • Reduced-order model comparing proposed system to existing technology. • Experimental test data from prototype test rig. - Abstract: This paper identifies the key technical requirements for a heavy truck auxiliary power unit (APU) and explores a potential alternative technology for use in a next-generation APU which could eliminate key problems related to emissions, noise and maintenance experienced today by conventional diesel engine-vapour compression APUs. The potential performance of a novel hybrid Stirling engine-adsorption chiller concept is investigated and benchmarked against the incumbent technology using a reduced-order model based on experimental data. Experimental results from a Stirling-adsorption system (SAS) prototype test rig are also presented which highlight system integration dynamics and overall performance. The adsorption chiller achieved an average COP of 0.42 ± 0.06 and 2.3 ± 0.1 kW_t of cooling capacity at the baseline test condition. The prototype SAS test rig demonstrates that there appear to be no major technology barriers remaining that would prevent adoption of the SAS concept in a next-generation APU. Such a system could offer a reduction of exhaust emissions, greenhouse gases (GHG), ozone-depleting substances, noise, low maintenance and the potential for fuel flexibility and higher reliability. Preliminary modelling results indicate that the proposed system could offer superior overall electrical and cooling efficiencies compared to incumbent APUs and demonstrate a payback period of 4.6 years.

  2. The 23rd Stirling Physics Meeting

    Science.gov (United States)

    1998-01-01

    derived from a standard Tesla coil with a high-Q secondary. This is capable of delivering around a million volts, which produce fantastic lightning flashes. A volunteer from the audience was invited to enter a huge Faraday Cage which was then subjected to these high voltage sparks! For a while the door of the cage jammed but eventually the victim emerged unscathed! This is, of course, not just an entertainment. The Gusto show is taken into schools and targeted at lower secondary pupils about to make their subject choices. The team also gives large scale physics demonstration lectures and could play to 10 000 children in a month. So physics is fun and physics is relevant to everyday life! Support for physics teachers Lesley Glasser chaired the afternoon session, which she opened by introducing the Institute's Education Officer. The Stirling Meeting would not be the same without the `commercial slot' presented again so ably by Catherine Wilson. Physics teachers are an endangered species and the Institute is determined to do whatever it can to support them. Plans are afoot to make sure the Schools Lectures are modified, if necessary, to take account of the educational differences in Scotland. The London-based `Physics in Perspective' course not only introduces sixth-formers to some of the frontiers of physics but gives enough free time for them to visit places of interest in the city - from the Science Museum to Soho. `So they associate physics with enjoyment!' Another Scottish Update Course is planned for teachers, and a brand new glossy booklet, sent free to all schools, will show pupils that choosing physics is a `Smart Move'. Finally the Institute has just started a major post-16 curriculum project which will include a variety of support materials to keep teachers abreast of continuing developments in physics. Each year, IoP Teacher of Physics Awards are given to `outstanding teachers of physics who inspire others to continue with and enjoy their physics'. Ann Jarvie

  3. Recovery of Exhaust Waste Heat for ICE Using the Beta Type Stirling Engine

    Directory of Open Access Journals (Sweden)

    Wail Aladayleh

    2015-01-01

    Full Text Available This paper investigates the potential of utilizing the exhaust waste heat using an integrated mechanical device with internal combustion engine for the automobiles to increase the fuel economy, the useful power, and the environment safety. One of the ways of utilizing waste heat is to use a Stirling engine. A Stirling engine requires only an external heat source as wasted heat for its operation. Because the exhaust gas temperature may reach 200 to 700°C, Stirling engine will work effectively. The indication work, real shaft power and specific fuel consumption for Stirling engine, and the exhaust power losses for IC engine are calculated. The study shows the availability and possibility of recovery of the waste heat from internal combustion engine using Stirling engine.

  4. Results from tests of a Stirling engine and wood chips gasifier plant

    DEFF Research Database (Denmark)

    Carlsen, Henrik; Bovin, Jonas Kabell; Werling, J.

    2002-01-01

    The combination of thermal gasification and a Stirling engine is an interesting concept for use in small Combined Heat and Power (CHP) plants based on biomass, because the need for gas cleaning is eliminated and problems with fouling of the Stirling engine heater are considerably reduced....... Furthermore, the overall electric efficiency of the system can be improved. At the Technical University of Denmark a small CHP plant based on a Stirling engine and an updraft gasifier has been developed and tested successfully. The advantages of updraft gasifiers are the simplicity and that the amount...... of the Stirling engine reduces the problems with tar to a minor problem in the design of the burner. The Stirling engine, which has an electric power output of 35 kW, is specifically designed for utilisation of fuels with a content of particles. The gas burner for the engine is designed for low specific energy...

  5. Performance analysis on free-piston Stirling cryocooler based on an idealized mathematical model

    Science.gov (United States)

    Guo, Y. X.; Chao, Y. J.; Gan, Z. H.; Li, S. Z.; Wang, B.

    2017-12-01

    Free-piston Stirling cryocoolers have extensive applications for its simplicity in structure and decrease in mass. However, the elimination of the motor and the crankshaft has made its thermodynamic characteristic different from that of Stirling cryocoolers with displacer driving mechanism. Therefore, an idealized mathematical model has been established, and with this model, an attempt has been made to analyse the thermodynamic characteristic and the performance of free-piston Stirling cryocooler. To certify this mathematical model, a comparison has been made between the model and a numerical model. This study reveals that due to the displacer damping force necessary for the production of cooling capacity, the free-piston Stirling cryocooler is inherently less efficient than Stirling cryocooler with displacer driving mechanism. Viscous flow resistance and incomplete heat transfer in the regenerator are the two major causes of the discrepancy between the results of the idealized mathematical model and the numerical model.

  6. Sci-Fri AM: Imaging - 09: Serial estimation of cross-talk for correction in dual-isotope imaging with dynamic tracers.

    Science.gov (United States)

    Wells, R G; Lockwood, J; Wei, L; Duan, D; Fernando, P; Bensimon, C; Ruddy, T D

    2012-07-01

    The recent radioisotope shortage has led to interest in non-Tc99m-based tracers. We have developed a novel I-123-labelled myocardial perfusion imaging tracer. We compare the I123-tracer to the clinical standard of Tc99m tetrofosmin in vivo in a rat model using a small-animal SPECT/CT camera. SPECT distinguishes different isotopes based on the different energies of the emitted gamma rays and thus allows simultaneous comparison of two tracer distributions in the same animal. Dual-isotope imaging is complicated by cross-talk between the energy windows of the isotopes. Standard energy-window-based correction methods are difficult to employ because of the proximity in energy of Tc99m (140keV) and I123 (159keV). Imaging the second tracer's energy window prior to its injection provides an estimate of the cross-talk. However, this estimate is only accurate if the tracer distribution is static. We use serial imaging prior to the introduction of the second tracer to estimate the dynamics of the first tracer and interpolate the cross-talk images to provide a more accurate correction. We used rat models of myocardial disease (n=3). I123 tracer was injected and imaged for one hour at 20min intervals. The Tc99m tetrofosmin was then injected and 30min later, a dual-isotope image was obtained. The impact of this approach is assessed by comparing the differences in the Tc99m-tetrofosmin image using this method with correction by simple correction for physical decay. The interpolative approach improves the accuracy of the correction by 2%-5% and thereby enhances the comparison of the two tracers. © 2012 American Association of Physicists in Medicine.

  7. The dynamics of CO2 fixation in the Southern Ocean as indicated by carboxylase activities and organic carbon isotopic ratios

    International Nuclear Information System (INIS)

    Fontugne, M.

    1991-01-01

    Recent studies have suggested a direct relationship between the dissolved CO 2 concentration and carbon isotopic composition of phytoplankton in surface ocean. Thus, measurement of δ 13 C of planktonic organic matter in deep-sea ocean cores can potentially yield a record of the past atmospheric CO 2 variations. However, results are presented from 3 cruises in Indian and Atlantic sectors of the Southern Ocean (between 40-66degS) in which biochemical and physiological factors associated with photosynthetic processes lead to carbon isotopic fractionation by phytoplankton which cannot be directly related to variations within the mineral carbon pool. Simultaneous measurements of the carboxylase activities in the 13 C/ 12 C ratio of particulate organic carbon show that there is a large variability in phytoplankton carbon metabolism, especially on a seasonal scale, in spite of a relative uniformity of the environmental conditions. Phytoplankton carbon metabolism is clearly a main factor governing variations in the stable isotopic composition of organic matter in the euphotic layer. Interrelationships between light, Rubiso activity and δ 13 C are clearly shown by the data. Heterotrophic processes may also influence the carbon isotope mass balance, especially during the break-up of the ice pack. In addition to the influence of photosynthetic metabolism, the effect of the meridoneal temperature gradient is also verified by the data set. (author). 24 refs.; 5 figs

  8. Determination of total selenium and Se-77 in isotopically enriched human samples by ICP-dynamic reaction cell-MS

    DEFF Research Database (Denmark)

    Sloth, Jens Jørgen; Larsen, Erik Huusfeldt; Bügel, Susanne H.

    2003-01-01

    and the digested faecal samples were diluted using an aqueous diluent containing 0.5% Triton X-100, 2% nitric acid and 3% methanol. Selenium was detected as Se-76, Se-77 and Se-80 by ICP- DRC- MS. Selenium originating from the natural isotope abundance yeast and other selenium sources from the diet was determined...

  9. Space Power Free-Piston Stirling Engine Scaling Study

    Science.gov (United States)

    Jones, D.

    1989-01-01

    The design feasibility study is documented of a single cylinder, free piston Stirling engine/linear alternator (FPSE/LA) power module generating 150 kW-electric (kW sub e), and the determination of the module's maximum feasible power level. The power module configuration was specified to be a single cylinder (single piston, single displacer) FPSE/LA, with tuning capacitors if required. The design requirements were as follows: (1) Maximum electrical power output; (2) Power module thermal efficiency equal to or greater than 20 percent at a specific mass of 5 to 8 kg/kW(sub e); (3) Heater wall temperature/cooler wall temperature = 1050 K/525 K; (4) Sodium heat-pipe heat transport system, pumped loop NaK (sodium-potassium eutectic mixture) rejection system; (5) Maximum power module vibration amplitude = 0.0038 cm; and (6) Design life = 7 years (60,000 hr). The results show that a single cylinder FPSE/LA is capable of meeting program goals and has attractive scaling attributes over the power range from 25 to 150 kW(sub e). Scaling beyond the 150 kW(sub e) power level, the power module efficiency falls and the power module specific mass reaches 10 kg/kW(sub e) at a power output of 500 kW(sub e). A discussion of scaling rules for the engine, alternator, and heat transport systems is presented, along with a detailed description of the conceptual design of a 150 kW(sub e) power module that meets the requirements. Included is a discussion of the design of a dynamic balance system. A parametric study of power module performance conducted over the power output range of 25 to 150 kW(sub e) for temperature ratios of 1.7, 2.0, 2.5, and 3.0 is presented and discussed. The results show that as the temperature ratio decreases, the efficiency falls and specific mass increases. At a temperature ratio of 1.7, the 150 kW(sub e) power module cannot satisfy both efficiency and specific mass goals. As the power level increases from 25 to 150 kW(sub e) at a fixed temperature ratio, power

  10. Seasonal variations in the nitrogen isotope composition of Okinotori coral in the tropical western Pacific: A new proxy for marine nitrate dynamics

    Science.gov (United States)

    Yamazaki, Atsuko; Watanabe, Tsuyoshi; Ogawa, Nanako O.; Ohkouchi, Naohiko; Shirai, Kotaro; Toratani, Mitsuhiro; Uematsu, Mitsuo

    2011-12-01

    To demonstrate the utility of coral skeletons as a recorder of nitrate dynamics in the surface ocean, we collected coral skeletons of Porites lobata and determined their nitrogen isotope composition (δ15Ncoral) from 2002 to 2006. Skeletons were collected at Okinotori Island in southwestern Japan, far from any sources of terrestrial nitrogen. Nitrogen isotope compositions along the growth direction were determined at 800 μm intervals (˜1 month resolution) and compared against the skeletal carbon isotope composition (δ13Ccoral-carb), barium/calcium ratio (Ba/Ca), and Chlorophyll-a concentration (Chl-a). From 2002 to 2004, ratios of the δ15Ncoral varied between +0.8 and +8.3‰ with inverse variation to SST (r = -0.53). Ba/Ca ratios and Chl-a concentrations were also observed to be high during seasons with low SST. These results suggested that the vertical mixing that occurs during periods of low SST carries nutrients from deeper water (δ15NDIN; +5˜+6‰) to the sea surface. In 2005 onward, δ15Ncoral and Ba/Ca ratios also had positive peaks even in high SST during periods of transient upwelling caused by frequent large typhoons (maximum wind speed 30 m/s). In addition, low δ15Ncoral (+0.8˜+2.0‰) four months after the last typhoon implied nitrogen fixation because of the lack of typhoon upwelling through the four years record of δ15Ncoral. Variations in the δ13Ccoral-carb and δ15Ncoral were synchronized, suggesting that nitrate concentration could control zooxanthellae photosynthesis. Our results suggested that δ15Ncoral holds promise as a proxy for reconstructing the transport dynamics of marine nitrate and thus also a tool for estimating nitrate origins in the tropical and subtropical oceans.

  11. Seasonal and inter-annual dynamics of growth, non-structural carbohydrates and C stable isotopes in a Mediterranean beech forest.

    Science.gov (United States)

    Scartazza, Andrea; Moscatello, Stefano; Matteucci, Giorgio; Battistelli, Alberto; Brugnoli, Enrico

    2013-07-01

    Seasonal and inter-annual dynamics of growth, non-structural carbohydrates (NSC) and carbon isotope composition (δ(13)C) of NSC were studied in a beech forest of Central Italy over a 2-year period characterized by different environmental conditions. The net C assimilated by forest trees was mainly used to sustain growth early in the season and to accumulate storage carbohydrates in trunk and root wood in the later part of the season, before leaf shedding. Growth and NSC concentration dynamics were only slightly affected by the reduced soil water content (SWC) during the drier year. Conversely, the carbon isotope analysis on NSC revealed seasonal and inter-annual variations of photosynthetic and post-carboxylation fractionation processes, with a significant increase in δ(13)C of wood and leaf soluble sugars in the drier summer year than in the wetter one. The highly significant correlation between δ(13)C of leaf soluble sugars and SWC suggests a decrease of the canopy C isotope discrimination and, hence, an increased water-use efficiency with decreasing soil water availability. This may be a relevant trait for maintaining an acceptable plant water status and a relatively high C sink capacity during dry seasonal periods. Our results suggest a short- to medium-term homeostatic response of the Collelongo beech stand to variations in water availability and solar radiation, indicating that this Mediterranean forest was able to adjust carbon-water balance in order to prevent C depletion and to sustain plant growth and reserve accumulation during relatively dry seasons.

  12. Hydrochemical and isotopic tracing of mixing dynamics and water quality evolution under pumping conditions in the mine shaft of the abandoned Frances Colliery, Scotland

    International Nuclear Information System (INIS)

    Elliot, Trevor; Younger, Paul L.

    2007-01-01

    Since 1995, when pumps were withdrawn from deep mines in East Fife (Scotland), mine waters have been rebounding throughout the coalfield. Recently, it has become necessary to pump and treat these waters to prevent their uncontrolled emergence at the surface. However, even relatively shallow pumping to surface treatment lagoons of the initially chemically-stratified mine water from a shaft in the coastal Frances Colliery during two dynamic step-drawdown tests to establish the hydraulic characteristics of the system resulted in rapid breakdown of the stratification within 24 h and a poor pumped water quality with high dissolved Fe loading. Further, data are presented here of hydrochemical and isotopic sampling of the extended pump testing lasting up to several weeks. The use in particular of the environmental isotopes δ 18 O, δ 2 H, δ 34 S, 3 H, 13 C and 14 C alongside hydrochemical and hydraulic pump test data allowed characterisation of the Frances system dynamics, mixing patterns and water quality sources feeding into this mineshaft under continuously pumped conditions. The pumped water quality reflects three significant components of mixing: shallow freshwater, seawater, and leakage from the surface treatment lagoons. In spite of the early impact of recirculating lagoon waters on the hydrochemistries, the highest Fe loadings in the longer-term pumped waters are identified with a mixed freshwater-seawater component affected by pyrite oxidation/melanterite dissolution in the subsurface system

  13. High Performance Split-Stirling Cooler Program

    Science.gov (United States)

    1982-09-01

    or crankcase subassembly includes the two drive cranks 1800 apart, the two motor bearings, the flywheel and target wheel . This assembly is dynamically...DISPLACER SEAL FRICTION REGENERATOR FLOW @ lOPSI E"I’ •’ REGENERATOR RUNOUT COMP. BRG. LUBRICATION "COMP. PISTON SEAL COMP. PISTON SEAL FRICTION INTER

  14. Proceedings of the 25th Annual Stirling Physics Meeting 1999

    Science.gov (United States)

    McVey, Michael

    1999-09-01

    trebling. Fractals were clearly visible. Jim of course dismissed all this as a property of the computer software. A real diode circuit was then produced and examined. Initially, for small input amplitudes, a sinusoidal input voltage produced a rectified sinusoidal output with the same period. The amplitude of the voltage input was then increased and the output voltage/time graph examined. The output period had now doubled. Further increases produced period trebling. Jim conceded there might be something in it but insisted on returning to the simple pendulum, which he thoroughly understood. Sarah agreed but wanted to examine a simple pendulum with forced oscillations using a computer model. Again, changing the size of the input force produced the characteristic period doubling seen in earlier examples. Basically he had to concede the argument. Sarah explained that chaotic systems exist in familiar contexts such as astronomy, meteorology, molecular vibrations, plasma physics, fluid dynamics and the stock market! Chaos limits scientists' ability to predict the future but has applications in, for example, detecting arrhythmic beating of the heart (period doubling again) and is the subject of much research. Chaotic systems are ones in which changes in initial conditions produce massively different outcomes. This chaotic effect may not be detectable until some time has elapsed from the input change. The final example was a meteorological one in which two slightly different weather charts were computer modelled over a period of several days and ended up predicting entirely different results. Jim Matthew concluded by thanking the technician who had assembled the demonstration apparatus. The audience had been treated to an entertaining, informative and thought-provoking presentation. London representative Catherine Wilson was delighted to be up at Stirling yet again. It was good, she said, to meet Alan Duncan for the first time and all the participants were to be congratulated on

  15. Design of stirling engine operating at low temperature difference

    Directory of Open Access Journals (Sweden)

    Sedlák Josef

    2018-01-01

    Full Text Available There are many sources of free energy available in the form of heat that is often simply wasted. The aim of this paper is to design and build a low temperature differential Stirling engine that would be powered exclusively from heat sources such as waste hot water or focused solar rays. A prototype is limited to a low temperature differential modification because of a choice of ABSplus plastic as a construction material for its key parts. The paper is divided into two parts. The first part covers a brief history of Stirling engine and its applications nowadays. Moreover, it describes basic principles of its operation that are supplemented by thermodynamic relations. Furthermore, an analysis of applied Fused Deposition Modelling has been done since the parts with more complex geometry had been manufactured using this additive technology. The second (experimental part covers 4 essential steps of a rapid prototyping method - Computer Aided Design of the 3D model of Stirling engine using parametric modeller Autodesk Inventor, production of its components using 3D printer uPrint, assembly and final testing. Special attention was devoted to last two steps of the process since the surfaces of the printed parts were sandpapered and sprayed. Parts, where an ABS plus plastic would have impeded the correct function, had been manufactured from aluminium and brass by cutting operations. Remaining parts had been bought in a hardware store as it would be uneconomical and unreasonable to manufacture them. Last two chapters of the paper describe final testing, mention the problems that appeared during its production and propose new approaches that could be used in the future to improve the project.

  16. Third generation development of an 11-watt Stirling converter

    International Nuclear Information System (INIS)

    Montgomery, W.L.; Ross, B.A.; Penswick, L.B.

    1996-01-01

    This paper describes recent design enhancements, performance results, and development of an artificial neural network (ANN) model related to the Radioisotope Stirling Generator (RSG), an 11-watt converter designed for remote power applications. Design enhancements include minor changes to improve performance, increase reliability, facilitate fabrication and assembly for limited production, and reduce mass. Innovative modifications were effected to increase performance and improve reliability of the vacuum foil insulation (VFI) package and linear alternator. High and low operating temperature acceptance testing of the Engineering Model (EM) demonstrated the robust system characteristics. These tests were conducted for 1 week of operation each, with rejector temperatures of 95 C and 20 C, respectively. Endurance testing continues for a complete Stirling converter, the Development Model (DM), with over 25,000 hours of maintenance-free operation. Endurance testing of flexures has attained over 540 flexure-years and endurance testing of linear motors/alternators has achieved nearly 27,000 hours of operation without failure. An ANN model was developed and tested successfully on the DM. Rejection temperatures were varied between 3 C and 75 C while load voltages ranged between engine stall and displacer overstroke. The trained ANN model, based solely on externally measured parameters, predicted values of piston amplitude, displacer amplitude, and piston-displacer phase angle within ±2% of the measured values over the entire operating regime. The ANN model demonstrated its effectiveness in the long-term evaluation of free-piston Stirling machines without adding the complexity, reduced reliability, and increased cost of sophisticated diagnostic instrumentation

  17. Advanced Stirling Convertor (ASC) Development for NASA RPS

    Science.gov (United States)

    Wong, Wayne A.; Wilson, Scott; Collins, Josh

    2014-01-01

    Sunpower's Advanced Stirling Convertor (ASC) initiated development under contract to the NASA Glenn Research Center (GRC) and after a series of successful demonstrations, the ASC began transitioning from a technology development project to flight development project. The ASC has very high power conversion efficiency making it attractive for future Radioisotope Power Systems (RPS) in order to make best use of the low plutonium-238 fuel inventory in the U.S. In recent years, the ASC became part of the NASA-Department of Energy Advanced Stirling Radioisotope Generator (ASRG) Integrated Project. Sunpower held two parallel contracts to produce ASC convertors, one with the Department of Energy/Lockheed Martin to produce the ASC-F flight convertors, and one with NASA GRC for the production of ASC-E3 engineering units, the initial units of which served as production pathfinders. The integrated ASC technical team successfully overcame various technical challenges that led to the completion and delivery of the first two pairs of flight-like ASC-E3 by 2013. However, in late Fall 2013, the DOE initiated termination of the Lockheed Martin ASRG flight development contract driven primarily by budget constraints. NASA continues to recognize the importance of high efficiency ASC power conversion for RPS and continues investment in the technology including the continuation of ASC-E3 production at Sunpower and the assembly of the ASRG Engineering Unit #2. This paper provides a summary of ASC technical accomplishments, overview of tests at GRC, plans for continued ASC production at Sunpower, and status of Stirling technology development.

  18. Screening of High Temperature Organic Materials for Future Stirling Convertors

    Science.gov (United States)

    Shin, Euy-sik E.; Scheiman, Daniel A.

    2017-01-01

    Along with major advancement of Stirling-based convertors, high temperature organics are needed to develop future higher temperature convertors for much improved efficiencies as well as to improve the margin of reliability for the current SOA (State-of-the-Art) convertors. The higher temperature capabilities would improve robustness of the convertors and also allow them to be used in additional missions, particularly ones that require a Venus flyby for a gravity assist. Various organic materials have been employed as essential components in the convertor for their unique properties and functions such as bonding, potting, sealing, thread locking, insulation, and lubrication. The Stirling convertor radioisotope generators have been developed for potential future space applications including Lunar/Mars surface power or a variety of spacecraft and vehicles, especially with a long mission cycle, sometimes up to 17 years, such as deep space exploration. Thus, performance, durability, and reliability of the organics should be critically evaluated in terms of every possible material structure-process-service environment relations based on the potential mission specifications. The initial efforts in screening the high temperature candidates focused on the most susceptible organics, such as adhesive, potting compound, O-ring, shrink tubing, and thread locker materials in conjunction with commercially available materials. More systematic and practical test methodologies that were developed and optimized based on the extensive organic evaluations and validations performed for various Stirling convertor types were employed to determine thermal stability, outgassing, and material compatibility of the selected organic candidates against their functional requirements. Processing and fabrication conditions and procedures were also optimized. This report presents results of the three-step candidate evaluation processes, their application limitations, and the final selection

  19. Advanced Stirling Convertor Development for NASA Radioisotope Power Systems

    Science.gov (United States)

    Wong, Wayne A.; Wilson, Scott D.; Collins, Josh

    2015-01-01

    Sunpower Inc.'s Advanced Stirling Convertor (ASC) initiated development under contract to the NASA Glenn Research Center and after a series of successful demonstrations, the ASC began transitioning from a technology development project to a flight development project. The ASC has very high power conversion efficiency making it attractive for future Radioisotope Power Systems (RPS) in order to make best use of the low plutonium-238 fuel inventory in the United States. In recent years, the ASC became part of the NASA and Department of Energy (DOE) Advanced Stirling Radioisotope Generator (ASRG) Integrated Project. Sunpower held two parallel contracts to produce ASCs, one with the DOE and Lockheed Martin to produce the ASC-F flight convertors, and one with NASA Glenn for the production of ASC-E3 engineering units, the initial units of which served as production pathfinders. The integrated ASC technical team successfully overcame various technical challenges that led to the completion and delivery of the first two pairs of flightlike ASC-E3 by 2013. However, in late fall 2013, the DOE initiated termination of the Lockheed Martin ASRG flight development contract driven primarily by budget constraints. NASA continues to recognize the importance of high-efficiency ASC power conversion for RPS and continues investment in the technology including the continuation of ASC-E3 production at Sunpower and the assembly of the ASRG Engineering Unit #2. This paper provides a summary of ASC technical accomplishments, overview of tests at Glenn, plans for continued ASC production at Sunpower, and status of Stirling technology development.

  20. Dynamic isotope effect on the product energy partitioning in CH2OH+→CHO++H2

    Science.gov (United States)

    Rhee, Young Min; Kim, Myung Soo

    1998-10-01

    The deuterium isotope effect on the product energy partitioning in the title reaction was investigated both experimentally and theoretically. The measured kinetic energy release (KER) showed a significant dependence on the position of deuteration. A reliable potential energy surface of the reaction was constructed from ab initio results using the recently developed interpolation algorithm. The classical trajectory calculation on this surface well reproduced the experimental finding. Close inspection of the potential energy surface revealed that the isotope effect on KER and the product rotations arose from the alteration of the symmetry of the reaction path near the transition state induced by the mass change upon isotopic substitution. The product vibrations were found to be affected by the change in the coupling constants which also arose from the mass-dependent change in the reaction path. Possibility of the quantum mechanical tunneling was also considered. Tunneling-corrected classical trajectory results were in excellent agreement with the experimental ones, indicating that the reaction proceeds via barrier penetration below the threshold.

  1. Thermodynamic design of Stirling engine using multi-objective particle swarm optimization algorithm

    International Nuclear Information System (INIS)

    Duan, Chen; Wang, Xinggang; Shu, Shuiming; Jing, Changwei; Chang, Huawei

    2014-01-01

    Highlights: • An improved thermodynamic model taking into account irreversibility parameter was developed. • A multi-objective optimization method for designing Stirling engine was investigated. • Multi-objective particle swarm optimization algorithm was adopted in the area of Stirling engine for the first time. - Abstract: In the recent years, the interest in Stirling engine has remarkably increased due to its ability to use any heat source from outside including solar energy, fossil fuels and biomass. A large number of studies have been done on Stirling cycle analysis. In the present study, a mathematical model based on thermodynamic analysis of Stirling engine considering regenerative losses and internal irreversibilities has been developed. Power output, thermal efficiency and the cycle irreversibility parameter of Stirling engine are optimized simultaneously using Particle Swarm Optimization (PSO) algorithm, which is more effective than traditional genetic algorithms. In this optimization problem, some important parameters of Stirling engine are considered as decision variables, such as temperatures of the working fluid both in the high temperature isothermal process and in the low temperature isothermal process, dead volume ratios of each heat exchanger, volumes of each working spaces, effectiveness of the regenerator, and the system charge pressure. The Pareto optimal frontier is obtained and the final design solution has been selected by Linear Programming Technique for Multidimensional Analysis of Preference (LINMAP). Results show that the proposed multi-objective optimization approach can significantly outperform traditional single objective approaches

  2. Overview of Multi-Kilowatt Free-Piston Stirling Power Conversion Research at Glenn Research Center

    Science.gov (United States)

    Geng, Steven M.; Mason, Lee S.; Dyson, Rodger W.; Penswick, L. Barry

    2008-01-01

    As a step towards development of Stirling power conversion for potential use in Fission Surface Power (FSP) systems, a pair of commercially available 1 kW class free-piston Stirling convertors and a pair of commercially available pressure wave generators (which will be plumbed together to create a high power Stirling linear alternator test rig) have been procured for in-house testing at Glenn Research Center (GRC). Delivery of both the Stirling convertors and the linear alternator test rig is expected by October 2007. The 1 kW class free-piston Stirling convertors will be tested at GRC to map and verify performance. The convertors will later be modified to operate with a NaK liquid metal pumped loop for thermal energy input. The high power linear alternator test rig will be used to map and verify high power Stirling linear alternator performance and to develop power management and distribution (PMAD) methods and techniques. This paper provides an overview of the multi-kilowatt free-piston Stirling power conversion work being performed at GRC.

  3. Overview of Multi-kilowatt Free-Piston Stirling Power Conversion Research at GRC

    Science.gov (United States)

    Geng, Steven M.; Mason, Lee S.; Dyson, Rodger W.; Penswick, L. Barry

    2008-01-01

    As a step towards development of Stirling power conversion for potential use in Fission Surface Power (FSP) systems, a pair of commercially available 1 kW class free-piston Stirling convertors and a pair of commercially available pressure wave generators (which will be plumbed together to create a high power Stirling linear alternator test rig) have been procured for in-house testing at Glenn Research Center. Delivery of both the Stirling convertors and the linear alternator test rig is expected by October, 2007. The 1 kW class free-piston Stirling convertors will be tested at GRC to map and verify performance. The convertors will later be modified to operate with a NaK liquid metal pumped loop for thermal energy input. The high power linear alternator test rig will be used to map and verify high power Stirling linear alternator performance and to develop power management and distribution (PMAD) methods and techniques. This paper provides an overview of the multi-kilowatt free-piston Stirling power conversion work being performed at GRC.

  4. Developmental Considerations on the Free-piston Stirling Power Convertor for Use in Space

    Science.gov (United States)

    Schreiber, Jeffrey G.

    2007-01-01

    Free-piston Stirling power conversion has been considered a candidate for radioisotope power systems for space for more than a decade. Prior to the free-piston Stirling architecture, systems were designed with kinematic Stirling engines with rotary alternators to convert heat to electricity. These systems were proposed with lightly loaded linkages to achieve the necessary life. When the free-piston configuration was initially proposed, it was thought to be attractive due to the relatively high conversion efficiency, acceptable mass, and the potential for long life and high reliability. These features have consistently been recognized by teams that have studied technology options for radioisotope power systems. Since free-piston Stirling power conversion was first considered for space power applications, there have been major advances in three general areas of development: demonstration of life and reliability, the success achieved by Stirling cryocoolers in flight, and the overall developmental maturity of the technology for both flight and terrestrial applications. Based on these advances, free-piston Stirling convertors are currently being developed for a number of terrestrial applications. They commonly operate with the power, efficiency, life, and reliability as intended, and much of the development now centers on system integration. This paper will summarize the accomplishments of free-piston Stirling power conversion technology over the past decade, review the status, and discuss the challenges that remain.

  5. Overview of Multi-Kilowatt Free-Piston Stirling Power Conversion Research at GRC

    Science.gov (United States)

    Geng, Steven M.; Mason, Lee S.; Dyson, Rodger W.; Penswick, L. Barry

    2008-01-01

    As a step towards development of Stirling power conversion for potential use in Fission Surface Power (FSP) systems, a pair of commercially available 1 kW class free-piston Stirling convertors and a pair of commercially available pressure wave generators (which will be plumbed together to create a high power Stirling linear alternator test rig) have been procured for in-house testing at Glenn Research Center. Delivery of both the Stirling convertors and the linear alternator test rig is expected by October, 2007. The 1 kW class free-piston Stirling convertors will be tested at GRC to map and verify performance. The convertors will later be modified to operate with a NaK liquid metal pumped loop for thermal energy input. The high power linear alternator test rig will be used to map and verify high power Stirling linear alternator performance and to develop power management and distribution (PMAD) methods and techniques. This paper provides an overview of the multi-kilowatt free-piston Stirling power conversion work being performed at GRC.

  6. Assessment of the Free-piston Stirling Convertor as a Long Life Power Convertor for Space

    Science.gov (United States)

    Schreiber, Jeffrey G.

    2001-01-01

    There is currently a renewed interest in the use of free-piston Stirling power convertors for space power applications. More specifically, the Stirling convertor is being developed to be part of the Stirling Radioisotope Power System to supply electric power to spacecraft for NASA deep space science missions. The current development effort involves the Department of Energy, Germantown, MD, the NASA Glenn Research Center, Cleveland, OH, and the Stirling Technology Company, Kennewick, WA. The Stirling convertor will absorb heat supplied from the decay of plutonium dioxide contained in the General Purpose Heat Source modules and convert it into electricity to power the spacecraft. For many years the "potentials" of the free-piston Stirling convertor have been publicized by it's developers. Among these "potentials" were long life and high reliability. This paper will present an overview of the critical areas that enable long life of the free-piston Stirling power convertor, and present some of the techniques that have been used when long life has been achieved.

  7. β Style Free-Piston Stirling Engine Control System Research

    Directory of Open Access Journals (Sweden)

    Xu Jian

    2016-01-01

    Full Text Available For the Free-Piston Stirling Engines (FPSE control system, a three -phase bridge circuit is reused as the system output about rectifier and start inverter. When FPSE system is in the power stage, the double closed loop control strategy and optimization algorithm of PI control parameters is adopted to ensure the highest system transmission efficiency under the requirements of the system output power and guarantee the stability of the running system. The simulation results prove the effectiveness of the above research content.

  8. Stochastic Stirling Engine Operating in Contact with Active Baths

    Directory of Open Access Journals (Sweden)

    Ruben Zakine

    2017-04-01

    Full Text Available A Stirling engine made of a colloidal particle in contact with a nonequilibrium bath is considered and analyzed with the tools of stochastic energetics. We model the bath by non Gaussian persistent noise acting on the colloidal particle. Depending on the chosen definition of an isothermal transformation in this nonequilibrium setting, we find that either the energetics of the engine parallels that of its equilibrium counterpart or, in the simplest case, that it ends up being less efficient. Persistence, more than non-Gaussian effects, are responsible for this result.

  9. Stochastic Stirling Engine Operating in Contact with Active Baths

    Science.gov (United States)

    Zakine, Ruben; Solon, Alexandre; Gingrich, Todd; van Wijland, Frédéric

    2017-04-01

    A Stirling engine made of a colloidal particle in contact with a nonequilibrium bath is considered and analyzed with the tools of stochastic energetics. We model the bath by non Gaussian persistent noise acting on the colloidal particle. Depending on the chosen definition of an isothermal transformation in this nonequilibrium setting, we find that either the energetics of the engine parallels that of its equilibrium counterpart or, in the simplest case, that it ends up being less efficient. Persistence, more than non Gaussian effects, are responsible for this result.

  10. NASA/DOE automotive Stirling engine project: Overview 1986

    Science.gov (United States)

    Beremand, D. G.; Shaltens, R. K.

    1986-01-01

    The DOE/NASA Automotive Stirling Engine Project is reviewed and its technical progress and status are presented. Key technologies in materials, seals, and piston rings are progressing well. Seven first-generation engines, and modifications thereto, have accumulated over 15,000 hr of test time, including 1100hr of in-vehicle testing. Results indicate good progress toward the program goals. The first second-generation engine is now undergoing initial testing. It is expected that the program goal of a 30-percent improvement in fuel economy will be achieved in tests of a second-generation engine in a Celebrity vehicle.

  11. EXPERIMENTAL INVESTIGATION OF AN AIR CHARGED LOW POWERED STIRLING ENGINE

    Directory of Open Access Journals (Sweden)

    Can ÇINAR

    2004-01-01

    Full Text Available In this study, an air charged, low powered manufactured ? type Stirling engine was investigated experimentally. Tests were conducted at 800, 900 and 1000 °C hot source temperatures, 1, 1.5, 2, 2.5, 3, 3.5 bars air charge pressure. The variation of engine power depending on the charge pressure and hot source temperature for two different heat transfer area was investigated experimentally. Maximum output power was obtained at 1000 °C and 3 bars charge pressure as 58 W at 441 rpm. Engine speed was reached at 846 rpm without load.

  12. Development of a Thermoacoustic Stirling Engine Technology Demonstrator

    Science.gov (United States)

    Reissner, Alexander; Gerger, Joachim; Hummel, Stefan; Reißig, Jannis; Pawelke, Roland

    2014-08-01

    Waste heat is a primary source of energy loss in many aerospace and terrestrial applications. FOTEC, an Austrian Research Company located in Wiener Neustadt, is presently developing a micro power converter, promising high efficiencies even for small- scale applications. The converter is based on an innovative thermoacoustic stirling engine concept without any moving parts. Such a maintenance-free engine system would be particularly suitable for advanced space power systems (radioisotope, waste heat) or even within the scope of terrestrial energy harvesting. This paper will summarizes the status of our ongoing efforts on this micro power converter technology.

  13. Integral finned heater and cooler for stirling engines

    Science.gov (United States)

    Corey, John A.

    1984-01-01

    A piston and cylinder for a Stirling engine and the like having top and bottom meshing or nesting finned conical surfaces to provide large surface areas in close proximity to the working gas for good thermal (addition and subtraction of heat) exchange to the working gas and elimination of the usual heater and cooler dead volume. The piston fins at the hot end of the cylinder are perforated to permit the gas to pass into the piston interior and through a regenerator contained therein.

  14. Benchmark Tests for Stirling Convertor Heater Head Life Assessment Conducted

    Science.gov (United States)

    Krause, David L.; Halford, Gary R.; Bowman, Randy R.

    2004-01-01

    A new in-house test capability has been developed at the NASA Glenn Research Center, where a critical component of the Stirling Radioisotope Generator (SRG) is undergoing extensive testing to aid the development of analytical life prediction methodology and to experimentally aid in verification of the flight-design component's life. The new facility includes two test rigs that are performing creep testing of the SRG heater head pressure vessel test articles at design temperature and with wall stresses ranging from operating level to seven times that (see the following photograph).

  15. Development and validation of the Stirling Eating Disorder Scales.

    Science.gov (United States)

    Williams, G J; Power, K G; Miller, H R; Freeman, C P; Yellowlees, A; Dowds, T; Walker, M; Parry-Jones, W L

    1994-07-01

    The development and reliability/validity check of an 80-item, 8-scale measure for use with eating disorder patients is presented. The Stirling Eating Disorder Scales (SEDS) assess anorexic dietary behavior, anorexic dietary cognitions, bulimic dietary behavior, bulimic dietary cognitions, high perceived external control, low assertiveness, low self-esteem, and self-directed hostility. The SEDS were administered to 82 eating disorder patients and 85 controls. Results indicate that the SEDS are acceptable in terms of internal consistency, reliability, group validity, and concurrent validity.

  16. Free-Piston Stirling Machine for Extreme Temperatures

    Science.gov (United States)

    Wood, James Gary (Inventor)

    2013-01-01

    A free piston Stirling machine including a thermal buffer tube extending from the machine's expansion space and surrounded by its heat rejector and its regenerator, a displacer cylinder extending from the thermal buffer tube to the compression space and surrounded by the heat rejecting heat exchanger, and a displacer that reciprocates within an excursion limit that extends into the regenerator by no more than 20% of the length of the regenerator during normal operation and preferably within excursion limits that are substantially the length of the heat rejector.

  17. A nonproprietary, nonsecret program for calculating Stirling cryocoolers

    Science.gov (United States)

    Martini, W. R.

    1985-01-01

    A design program for an integrated Stirling cycle cryocooler was written on an IBM-PC computer. The program is easy to use and shows the trends and itemizes the losses. The calculated results were compared with some measured performance values. The program predicts somewhat optimistic performance and needs to be calibrated more with experimental measurements. Adding a multiplier to the friction factor can bring the calculated rsults in line with the limited test results so far available. The program is offered as a good framework on which to build a truly useful design program for all types of cryocoolers.

  18. Isotopic clusters

    International Nuclear Information System (INIS)

    Geraedts, J.M.P.

    1983-01-01

    Spectra of isotopically mixed clusters (dimers of SF 6 ) are calculated as well as transition frequencies. The result leads to speculations about the suitability of the laser-cluster fragmentation process for isotope separation. (Auth.)

  19. Seasonal dynamics of stable isotopes and element ratios in authigenic calcites during their precipitation and dissolution, Sacrower See (northeastern Germany

    Directory of Open Access Journals (Sweden)

    Bernd ZOLITSCHKA

    2009-08-01

    Full Text Available The seasonal evolution of chemical and physical water properties as well as particle fluxes was monitored in Sacrower See (northeastern Germany during two consecutive years (Oct 2003 - Oct 2005. Additonally, we measured δ18O and δ13C as well as Sr:Ca and Mg:Ca ratios of authigenic calcites that were collected in sequencing sediment traps in order to disentangle environmental and climatic factors controlling these parameters. In particular, our aim was to find out if element ratios and the isotopic composition of calcites reflect changes in water and air temperatures. Lake water is highly enriched in 18O (-1.3 to -2.5‰ VSMOW with an evaporative increase of 0.6‰ during summer. Values are 5-6‰ more positive than groundwater values and 4-5‰ more positive than long-term weighted annual means of precipitation. During spring and summer, high amounts of dissolved phosphate cause eutrophic conditions and calcite precipitation in isotopic disequilibrium. Measured values are depleted in 18O by 2 to 10‰ compared to calculated equilibrium values. Resuspension and partial dissolution of calcite in the water column contribute to this isotopic divergence in summer and autumn as δ18Oca and δ13C values increased in the hypolimnion during this time. Mg:Ca and Sr:Ca ratios are altered by dissolution as well. In the hypolimnion these ratios were higher than in the epilimnion. Another reason for the huge deviation between measured and theoretical δ18Oca values during summer is the occurrence of large amounts of Phacotus lenticularis in the carbonate fraction. High amounts of Phacotus lead to more negative δ18Oca and more positive δ13C values. Several characteristics of δ18Oca and δ13C are also reflected by Mg:Ca and Sr:Ca ratios and isotopic composition of oxygen and carbon were influenced by the onset and stability of stratification. Especially the earlier onset of stratification in 2005 caused higher sediment fluxes and more positive carbon and

  20. Stable isotopes

    International Nuclear Information System (INIS)

    Evans, D.K.

    1986-01-01

    Seventy-five percent of the world's stable isotope supply comes from one producer, Oak Ridge Nuclear Laboratory (ORNL) in the US. Canadian concern is that foreign needs will be met only after domestic needs, thus creating a shortage of stable isotopes in Canada. This article describes the present situation in Canada (availability and cost) of stable isotopes, the isotope enrichment techniques, and related research programs at Chalk River Nuclear Laboratories (CRNL)

  1. Isotope separation

    International Nuclear Information System (INIS)

    Eerkens, J.W.

    1979-01-01

    A method of isotope separation is described which involves the use of a laser photon beam to selectively induce energy level transitions of an isotope molecule containing the isotope to be separated. The use of the technique for 235 U enrichment is demonstrated. (UK)

  2. Biomass gasification integrated with a solid oxide fuel cell and Stirling engine

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2014-01-01

    An integrated gasification solid oxide fuel cell (SOFC) and Stirling engine for combined heat and power application is analyzed. The target for electricity production is 120 kW. Woodchips are used as gasification feedstock to produce syngas, which is then used to feed the SOFC stacks...... for electricity production. Unreacted hydrocarbons remaining after the SOFC are burned in a catalytic burner, and the hot off-gases from the burner are recovered in a Stirling engine for electricity and heat production. Domestic hot water is used as a heat sink for the Stirling engine. A complete balance...

  3. Study of Stirling Engine Efficiency Coefficient under Conditions Being Close to Real Ones

    Directory of Open Access Journals (Sweden)

    R. M. Abramian

    2013-01-01

    Full Text Available An absolute internal efficiency coefficient of the Stirling engine has been obtained without regenerator and with regenerator under conditions when van der Waals gas serves as a working medium. The paper reveals that while taking into account own volume of molecules thermal efficiency coefficient of the Stirling engine depends on mole number of the working medium  and it is slightly increasing  in comparison with the case of an ideal gas. The paper gives consideration to heat losses while the Stirling machine operates with heat regeneration. Dependence of regeneration rate on time of heat transfer has been obtained in the paper. 

  4. Assessment of 25 kW free-piston Stirling technology alternatives for solar applications

    Science.gov (United States)

    Erbeznik, Raymond M.; White, Maurice A.; Penswick, L. B.; Neely, Ronald E.; Ritter, Darren C.; Wallace, David A.

    1992-01-01

    The final design, construction, and testing of a 25-kW free-piston advanced Stirling conversion system (ASCS) are examined. The final design of the free-piston hydraulic ASCS consists of five subsystems: heat transport subsystem (solar receiver and pool boiler), free-piston hydraulic Stirling engine, hydraulic subsystem, cooling subsystem, and electrical and control subsystem. Advantages and disadvantages are identified for each technology alternative. Technology alternatives considered are gas bearings vs flexure bearings, stationary magnet linear alternator vs moving magnetic linear alternator, and seven different control options. Component designs are generated using available in-house procedures to meet the requirements of the free-piston Stirling convertor configurations.

  5. Optimized Heat Pipe Backup Cooling System Tested with a Stirling Convertor

    Science.gov (United States)

    Schwendeman, Carl L.; Tarau, Calin; Schifer, Nicholas A.; Anderson, William G.; Garner, Scott

    2016-01-01

    In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal variable conductance heat pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor by bypassing the heat during stops. In a previous NASA Small Business Innovation Research (SBIR) Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for the Stirling RPS. In 2012, one of these VCHPs was successfully tested at NASA Glenn Research Center with a Stirling convertor as an Advanced Stirling Radioisotope Generator (ASRG) backup cooling system. The prototype; however, was not optimized and did not reflect the final heat rejection path. ACT through further funding has developed a semioptimized prototype with the finalized heat path for testing at Glenn with a Stirling convertor. The semioptimized system features a two-phase radiator and is significantly smaller and lighter than the prior prototype to reflect a higher level of flight readiness. The VCHP is designed to activate and remove heat from the GPHS during stoppage with a small temperature increase from the nominal vapor temperature. This small temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the multilayer insulation (MLI). The VCHP passively allows the Stirling convertor to be turned off multiple times during a mission with potentially unlimited off durations. Having the ability to turn the Stirling off allows for the Stirling to be reset and reduces vibrations on the platform during sensitive measurements or

  6. A simple method of calculating Stirling engines for engine design optimization

    Science.gov (United States)

    Martini, W. R.

    1978-01-01

    A calculation method is presented for a rhombic drive Stirling engine with a tubular heater and cooler and a screen type regenerator. Generally the equations presented describe power generation and consumption and heat losses. It is the simplest type of analysis that takes into account the conflicting requirements inherent in Stirling engine design. The method itemizes the power and heat losses for intelligent engine optimization. The results of engine analysis of the GPU-3 Stirling engine are compared with more complicated engine analysis and with engine measurements.

  7. Análisis de irreversibilidades en el comportamiento de un motor Stirling // Analysis of irreversibilities on performance of a Stirling engine

    Directory of Open Access Journals (Sweden)

    Juan José González-Bayón

    2011-05-01

    Full Text Available El objetivo de este estudio es determinar el efecto de las irreversibilidades (internas y externasdebidas a la transferencia de calor y las pérdidas de presión debidas a la fricción sobre elrendimiento de Segunda Ley de un motor Stirling de tipo considerando el volumen muerto. Elmotor Stirling es analizado usando un modelo matemático basado en las leyes de la termodinámicapara procesos con una velocidad finita. Se asume un modelo isotérmico de motor con volúmenes deespacio muerto en la zona caliente, zona fría y en el regenerador. Los resultados obtenidos muestranque a pesar de que teóricamente el motor Stirling posee un rendimiento igual al de Carnot, en lapráctica su rendimiento puede ser de 2 a 5 veces menor que éste, dependiendo de la eficiencia delregenerador, del volumen muerto, de la diferencia de temperatura entre fluido y focos térmicos y delas rpm a que se opere el motor.Palabras claves: motor Stirling, motor térmico regenerativo, análisis de irreversibilidades.____________________________________________________________________AbstractThe study aims to determine the effect of the internal and external irreversibilities caused by heattransfer and pressure losses due to friction on the Second Law performance of a Stirling engine tipewith death volume include. The Stirling engine is analyzed using a mathematical model based onthe laws of thermodynamics for processes with finite speed. It is assumed an isothermic model of themotor with death volume on hot zone, cold zone and regenerator. The results of this study show thatthe real cycle efficiency of the Sirling engine is approximately 2 to 5 times minor than the efficiency ofCarnot cycle as function of the regenerator efficiency, death volume, temperature difference betweenfluid and termic source and motor speed.Key words: stirling engine, regenerative heat engine, irreversibilities analysis.

  8. Preliminary results from a four-working space, double-acting piston, Stirling engine controls model

    Science.gov (United States)

    Daniele, C. J.; Lorenzo, C. F.

    1980-01-01

    A four working space, double acting piston, Stirling engine simulation is being developed for controls studies. The development method is to construct two simulations, one for detailed fluid behavior, and a second model with simple fluid behaviour but containing the four working space aspects and engine inertias, validate these models separately, then upgrade the four working space model by incorporating the detailed fluid behaviour model for all four working spaces. The single working space (SWS) model contains the detailed fluid dynamics. It has seven control volumes in which continuity, energy, and pressure loss effects are simulated. Comparison of the SWS model with experimental data shows reasonable agreement in net power versus speed characteristics for various mean pressure levels in the working space. The four working space (FWS) model was built to observe the behaviour of the whole engine. The drive dynamics and vehicle inertia effects are simulated. To reduce calculation time, only three volumes are used in each working space and the gas temperature are fixed (no energy equation). Comparison of the FWS model predicted power with experimental data shows reasonable agreement. Since all four working spaces are simulated, the unique capabilities of the model are exercised to look at working fluid supply transients, short circuit transients, and piston ring leakage effects.

  9. Dynamics of Indian Ocean Slavery Revealed through Isotopic Data from the Colonial Era Cobern Street Burial Site, Cape Town, South Africa (1750-1827)

    Science.gov (United States)

    Morris, Alan G.; Kars, Henk; Davies, Gareth R.

    2016-01-01

    The Dutch East India Company (VOC) intended the Cape of Good Hope to be a refreshment stop for ships travelling between the Netherlands and its eastern colonies. The indigenous Khoisan, however, did not constitute an adequate workforce, therefore the VOC imported slaves from East Africa, Madagascar and Asia to expand the workforce. Cape Town became a cosmopolitan settlement with different categories of people, amongst them a non-European underclass that consisted of slaves, exiles, convicts and free-blacks. This study integrated new strontium isotope data with carbon and nitrogen isotope results from an 18th-19th century burial ground at Cobern Street, Cape Town, to identify non-European forced migrants to the Cape. The aim of the study was to elucidate individual mobility patterns, the age at which the forced migration took place and, if possible, geographical provenance. Using three proxies, 87Sr/86Sr, δ13Cdentine and the presence of dental modifications, a majority (54.5%) of the individuals were found to be born non-locally. In addition, the 87Sr/86Sr data suggested that the non-locally born men came from more diverse geographic origins than the migrant women. Possible provenances were suggested for two individuals. These results contribute to an improved understanding of the dynamics of slave trading in the Indian Ocean world. PMID:27309532

  10. Stable isotopes of bulk organic matter to trace carbon and nitrogen dynamics in an estuarine ecosystem in Babitonga Bay (Santa Catarina, Brazil)

    International Nuclear Information System (INIS)

    Barros, Grace Virginia; Martinelli, Luiz Antonio; Oliveira Novais, Therezinha M.; Ometto, Jean Pierre H.B.; Zuppi, Gian Maria

    2010-01-01

    The biogeochemical processes affecting the transport and cycling of terrestrial organic carbon in coastal and transition areas are still not fully understood. One means of distinguishing between the sources of organic materials contributing to particulate organic matter (POM) in Babitonga Bay waters and sediments is by the direct measurement of δ 13 C of dissolved inorganic carbon (DIC) and δ 13 C and δ 15 N in the organic constituents. An isotopic survey was taken from samples collected in the Bay in late spring of 2004. The results indicate that the δ 13 C and δ 15 N compositions of OM varied from - 21.7 per mille to - 26.2 per mille and from + 9.2 per mille to - 0.1 per mille , respectively. δ 13 C from DIC ranges from + 0.04 per mille to - 12.7 per mille . The difference in the isotope compositions enables the determination of three distinct end-members: terrestrial, marine and urban. Moreover, the evaluation of source contribution to the particulate organic matter (POM) in the Bay, enables assessment of the anthropogenic impact. Comparing the depleted values of δ 13 C DIC and δ 13 C POC it is possible to further understand the carbon dynamic within Babitonga Bay.

  11. Dynamics of Carbonates in Soils under Different Land Use in Forest-Steppe Area of Russia Using Stable and Radiogenic Carbon Isotope Data

    Directory of Open Access Journals (Sweden)

    Olga Khokhlova

    2018-04-01

    Full Text Available The work is aimed at the analysis of carbonate dynamics in soils under different land use. The studied area is located in the forest steppe - of the Central Russian Upland. Soils were sampled at four sites: a broadleaf forest, an adjacent 50-year continuously cropped field including plots under a corn monoculture, bare fallow, and a crop rotation area with a clean fallow every fourth year. The carbonates’ morphology, their chemical composition, as well as their stable and radiogenic isotopes of carbon were studied. Clear-cut distinctions were found in the carbonate distribution throughout the profiles in the microstructure of carbonate pedofeatures, carbon isotopic composition, and radiocarbon age of carbonates between the pairs of the plots as follows: the bare fallow and the crop rotation on the one hand, and the corn monoculture and forest on the other. The distinctions are commonly assumed to result from repeating upward water fluxes, which are different in the bare soils and those with plant cover. A clear difference occurred in the hydrothermal regime for soils with and without plant cover, and was found to be the key factor of the observed differences. In addition, in soils under plant cover, the carbonate migration upward occurs due to process of transpiration, whereas in soils devoid of plants, it occurs due to physical evaporation.

  12. Dynamics of Indian Ocean Slavery Revealed through Isotopic Data from the Colonial Era Cobern Street Burial Site, Cape Town, South Africa (1750-1827).

    Science.gov (United States)

    Kootker, Lisette M; Mbeki, Linda; Morris, Alan G; Kars, Henk; Davies, Gareth R

    2016-01-01

    The Dutch East India Company (VOC) intended the Cape of Good Hope to be a refreshment stop for ships travelling between the Netherlands and its eastern colonies. The indigenous Khoisan, however, did not constitute an adequate workforce, therefore the VOC imported slaves from East Africa, Madagascar and Asia to expand the workforce. Cape Town became a cosmopolitan settlement with different categories of people, amongst them a non-European underclass that consisted of slaves, exiles, convicts and free-blacks. This study integrated new strontium isotope data with carbon and nitrogen isotope results from an 18th-19th century burial ground at Cobern Street, Cape Town, to identify non-European forced migrants to the Cape. The aim of the study was to elucidate individual mobility patterns, the age at which the forced migration took place and, if possible, geographical provenance. Using three proxies, 87Sr/86Sr, δ13Cdentine and the presence of dental modifications, a majority (54.5%) of the individuals were found to be born non-locally. In addition, the 87Sr/86Sr data suggested that the non-locally born men came from more diverse geographic origins than the migrant women. Possible provenances were suggested for two individuals. These results contribute to an improved understanding of the dynamics of slave trading in the Indian Ocean world.

  13. Dynamics of Indian Ocean Slavery Revealed through Isotopic Data from the Colonial Era Cobern Street Burial Site, Cape Town, South Africa (1750-1827.

    Directory of Open Access Journals (Sweden)

    Lisette M Kootker

    Full Text Available The Dutch East India Company (VOC intended the Cape of Good Hope to be a refreshment stop for ships travelling between the Netherlands and its eastern colonies. The indigenous Khoisan, however, did not constitute an adequate workforce, therefore the VOC imported slaves from East Africa, Madagascar and Asia to expand the workforce. Cape Town became a cosmopolitan settlement with different categories of people, amongst them a non-European underclass that consisted of slaves, exiles, convicts and free-blacks. This study integrated new strontium isotope data with carbon and nitrogen isotope results from an 18th-19th century burial ground at Cobern Street, Cape Town, to identify non-European forced migrants to the Cape. The aim of the study was to elucidate individual mobility patterns, the age at which the forced migration took place and, if possible, geographical provenance. Using three proxies, 87Sr/86Sr, δ13Cdentine and the presence of dental modifications, a majority (54.5% of the individuals were found to be born non-locally. In addition, the 87Sr/86Sr data suggested that the non-locally born men came from more diverse geographic origins than the migrant women. Possible provenances were suggested for two individuals. These results contribute to an improved understanding of the dynamics of slave trading in the Indian Ocean world.

  14. Estimation of percolating water dynamics through the vadose zone of the Postojna cave on the basis of isotope composition

    Directory of Open Access Journals (Sweden)

    Janja Kogovšek

    2007-12-01

    Full Text Available Within the scope of monitoring water percolation through the 100-m thick vadose zone in the area of Postojnska jama continuous measurements of precipitation were carried out on the surface, and continuous measurements of water flowandphysicalandchemicalparametersof selected water trickles were performed under the surface. Occasional samples of percolating waters were taken for the analysis of water oxygen isotope composition. An exponential model of groundwater flowwaselaborated,bymeansofwhichtheretentiontime of water in individual trickles was estimated. Modelled retention times of groundwater range from 2.5 months to over one year.

  15. Many-objective thermodynamic optimization of Stirling heat engine

    International Nuclear Information System (INIS)

    Patel, Vivek; Savsani, Vimal; Mudgal, Anurag

    2017-01-01

    This paper presents a rigorous investigation of many-objective (four-objective) thermodynamic optimization of a Stirling heat engine. Many-objective optimization problem is formed by considering maximization of thermal efficiency, power output, ecological function and exergy efficiency. Multi-objective heat transfer search (MOHTS) algorithm is proposed and applied to obtain a set of Pareto-optimal points. Many objective optimization results form a solution in a four dimensional hyper objective space and for visualization it is represented on a two dimension objective space. Thus, results of four-objective optimization are represented by six Pareto fronts in two dimension objective space. These six Pareto fronts are compared with their corresponding two-objective Pareto fronts. Quantitative assessment of the obtained Pareto solutions is reported in terms of spread and the spacing measures. Different decision making approaches such as LINMAP, TOPSIS and fuzzy are used to select a final optimal solution from Pareto optimal set of many-objective optimization. Finally, to reveal the level of conflict between these objectives, distribution of each decision variable in their allowable range is also shown in two dimensional objective spaces. - Highlights: • Many-objective (i.e. four objective) optimization of Stirling engine is investigated. • MOHTS algorithm is introduced and applied to obtain a set of Pareto points. • Comparative results of many-objective and multi-objectives are presented. • Relationship of design variables in many-objective optimization are obtained. • Optimum solution is selected by using decision making approaches.

  16. Progress in High Power Free-Piston Stirling Convertor Development

    Science.gov (United States)

    Brandhorst, Henry W., Jr.; Kirby, Raymond L.; Chapman, Peter A.; Walter, Thomas J.

    2008-09-01

    The U.S. Space Exploration Policy has established a vision for human exploration of the moon and Mars. One option for power for future outposts on the lunar and Martian surfaces is a nuclear reactor coupled with a free-piston Stirling convertor at a power level of 30-40 kWe. A 25 kW convertor was developed in the 1990s under the SP-100 program. This system consisted of two 12.5 kWe engines connected at their hot ends and mounted in tandem to cancel vibration. Recently, NASA began a new project with Auburn University to develop a 5 kWe, single convertor for use in such a possible lunar power system. Goals of this development program include a specific power in excess of 140 We/kg at the convertor level, lifetime in excess of five years and a control system that will safely manage the convertors in case of an emergency. Foster-Miller, Inc. is developing the 5 kWe Stirling Convertor Assembly. The characteristics of the design along with progress in developing the system will be described.

  17. Magnetic bearings for free-piston Stirling engines

    Science.gov (United States)

    Curwen, P. W.; Fleming, D. P.; Rao, D. K.; Wilson, D. S.

    1992-01-01

    The feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery currently being developed for long-term space missions are assessed. The study was performed for a 50-kWe Reference Stirling Space Power Converter (RSSPC) which currently uses hydrostatic gas bearings to support the reciprocating displacer and power piston assemblies. Active magnetic bearings of the attractive electromagnetic type are feasible for the RSSPC power piston. Magnetic support of the displacer assembly would require unacceptable changes to the design of the current RSSPC. However, magnetic suspension of both displacer and power piston is feasible for a relative-displacer version of the RSSPC. Magnetic suspension of the RSSPC power piston can potentially increase overall efficiency by 0.5 to 1 percent (0.1 to 0.3 efficiency points). Magnetic bearings will also overcome several operational concerns associated with hydrostatic gas bearing systems. These advantages, however, are accompanied by a 5 percent increase in specific mass of the RSSPC.

  18. Development of a small Stirling cycle cooler for spaceflight applications

    International Nuclear Information System (INIS)

    Werrett, S.T.; Bradshaw, T.W.; Davey, G.; Delderfield, T.W.; Peskett, G.D.

    1986-01-01

    This paper describes the development, from a previously proven design approach, of a robust and simple Stirling cycle cooler with long life potential. The need for a closed cycle refrigerator for use in a spacecraft borne infra-red radiometer is explained. The refrigerator is to supply 1 watt of cooling at 80 K for less than 80 watts of input power, be able to survive the launch environment and subsequently run for 26000 hours. Clearance seals achieved with a spring suspension developed from earlier space proven mechanisms have led to the production of a linear split Stirling cycle machine with no apparent life limiting features. A servo control system, in conjunction with moving coil motors and LVDT position sensors, permits running of balanced pairs of mechanisms. The working fluid, helium at a pressure of 1.2 MPa, is contained within titanium bodies having gold O-ring seals. A vacuum bakeout procedure, based upon experience and outgassing trials, reduces residual contaminant release to acceptable levels. A prototype refrigerator has been subjected to a vibration test and has subsequently run for 6000 hours with no detectable change in performance

  19. General performance characteristics of an irreversible ferromagnetic Stirling refrigeration cycle

    International Nuclear Information System (INIS)

    Lin, G.; Tegus, O.; Zhang, L.; Brueck, E.

    2004-01-01

    A new magnetic-refrigeration-cycle model using ferromagnetic materials as a cyclic working substance is set up, in which finite-rate heat transfer, heat leak and regeneration time are taken into account. On the basis of the thermodynamic properties of a ferromagnetic material, the general performance characteristics of the ferromagnetic Stirling refrigeration cycle are investigated and the effects of some key irreversibilities on the performance of the cycle are revealed. By using the optimal-control theory, the optimal relation between the coefficient of performance and the cooling rate is derived and some important performance bounds, e.g., the maximum cooling rate, the maximum coefficient of performance, are determined. Moreover, the optimal operating regions for cooling rate, coefficient of performance and the optimal operating temperatures of a cyclic working substance in the two heat-transfer processes are obtained. Furthermore, the influences of magnetization and magnetic field on the performance characteristics of the cycle are discussed. The results obtained here have general significance and can be deduced to the related ones of the Stirling refrigeration cycle using paramagnetic salt as a cyclic working substance

  20. Controlled rate cooling of fungi using a stirling cycle freezer.

    Science.gov (United States)

    Ryan, Matthew J; Kasulyte-Creasey, Daiva; Kermode, Anthony; San, Shwe Phue; Buddie, Alan G

    2014-01-01

    The use of a Stirling cycle freezer for cryopreservation is considered to have significant advantages over traditional methodologies including N2 free operation, application of low cooling rates, reduction of sample contamination risks and control of ice nucleation. The study assesses the suitability of an 'N2-free' Stirling Cycle controlled rate freezer for fungi cryopreservation. In total, 77 fungi representing a broad taxonomic coverage were cooled using the N2 free cooler following a cooling rate of -1 degrees C min(-1). Of these, 15 strains were also cryopreserved using a traditional 'N2 gas chamber' controlled rate cooler and a comparison of culture morphology and genomic stability against non-cryopreserved starter cultures was undertaken. In total of 75 fungi survived cryopreservation, only a recalcitrant Basidiomycete and filamentous Chromist failed to survive. No changes were detected in genomic profile after preservation, suggesting that genomic function is not adversely compromised as a result of using 'N2 free' cooling. The results demonstrate the potential of 'N2-free' cooling for the routine cryopreservation of fungi in Biological Resource Centres.

  1. Advanced Stirling Convertor (ASC) Technology Maturation in Preparation for Flight

    Science.gov (United States)

    Wong, Wayne A.; Cornell, Peggy A.

    2012-01-01

    The Advanced Stirling Convertor (ASC) is being developed by an integrated team of Sunpower and National Aeronautics and Space Administration s (NASA s) Glenn Research Center (GRC). The ASC development, funded by NASA s Science Mission Directorate, started as a technology development effort in 2003 and has since evolved through progressive convertor builds and successful testing to demonstrate high conversion efficiency, low mass, and capability to meet long-life Radioisotope Power System (RPS) requirements. The technology has been adopted by the Department of Energy and Lockheed Martin Space Systems Company s Advanced Stirling Radioisotope Generator (ASRG), which has been selected for potential flight demonstration on Discovery 12. This paper provides an overview of the status of ASC development including the most recent ASC-E2 convertors that have been delivered to GRC and an introduction to the ASC-E3 and ASC flight convertors that Sunpower will build next. The paper also describes the technology maturation and support tasks being conducted at GRC to support ASC and ASRG development in the areas of convertor and generator extended operation, high-temperature materials, heater head life assessment, organics, nondestructive inspection, spring fatigue testing, and other reliability verification tasks.

  2. Performance Measurement of Advanced Stirling Convertors (ASC-E3)

    Science.gov (United States)

    Oriti, Salvatore M.

    2013-01-01

    NASA Glenn Research Center (GRC) has been supporting development of the Advanced Stirling Radioisotope Generator (ASRG) since 2006. A key element of the ASRG project is providing life, reliability, and performance testing data of the Advanced Stirling Convertor (ASC). The latest version of the ASC (ASC-E3, to represent the third cycle of engineering model test hardware) is of a design identical to the forthcoming flight convertors. For this generation of hardware, a joint Sunpower and GRC effort was initiated to improve and standardize the test support hardware. After this effort was completed, the first pair of ASC-E3 units was produced by Sunpower and then delivered to GRC in December 2012. GRC has begun operation of these units. This process included performance verification, which examined the data from various tests to validate the convertor performance to the product specification. Other tests included detailed performance mapping that encompassed the wide range of operating conditions that will exist during a mission. These convertors were then transferred to Lockheed Martin for controller checkout testing. The results of this latest convertor performance verification activity are summarized here.

  3. A Microfabricated Involute-Foil Regenerator for Stirling Engines

    Science.gov (United States)

    Tew, Roy; Ibrahim, Mounir; Danila, Daniel; Simon, Terrence; Mantell, Susan; Sun, Liyong; Gedeon, David; Kelly, Kevin; McLean, Jeffrey; Qiu, Songgang

    2007-01-01

    A segmented involute-foil regenerator has been designed, microfabricated and tested in an oscillating-flow rig with excellent results. During the Phase I effort, several approximations of parallel-plate regenerator geometry were chosen as potential candidates for a new microfabrication concept. Potential manufacturers and processes were surveyed. The selected concept consisted of stacked segmented-involute-foil disks (or annular portions of disks), originally to be microfabricated from stainless-steel via the LiGA (lithography, electroplating, and molding) process and EDM. During Phase II, re-planning of the effort led to test plans based on nickel disks, microfabricated via the LiGA process, only. A stack of nickel segmented-involute-foil disks was tested in an oscillating-flow test rig. These test results yielded a performance figure of merit (roughly the ratio of heat transfer to pressure drop) of about twice that of the 90 percent random fiber currently used in small approx.100 W Stirling space-power convertors-in the Reynolds Number range of interest (50 to 100). A Phase III effort is now underway to fabricate and test a segmented-involute-foil regenerator in a Stirling convertor. Though funding limitations prevent optimization of the Stirling engine geometry for use with this regenerator, the Sage computer code will be used to help evaluate the engine test results. Previous Sage Stirling model projections have indicated that a segmented-involute-foil regenerator is capable of improving the performance of an optimized involute-foil engine by 6 to 9 percent; it is also anticipated that such involute-foil geometries will be more reliable and easier to manufacture with tight-tolerance characteristics, than random-fiber or wire-screen regenerators. Beyond the near-term Phase III regenerator fabrication and engine testing, other goals are (1) fabrication from a material suitable for high temperature Stirling operation (up to 850 C for current engines; up to 1200 C

  4. Design, construction and experimental investigation of a Stirling refrigerator for freezing in supermarkets. Final report; Auslegung, Bau und experimentelle Untersuchung einer Stirling-Kaeltemaschine fuer die Tiefkuehlung in Supermaerkten. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Steimle, F.; Schikora, H.; Mai, M.; Siegel, A.

    2000-10-01

    Several theoretical investigations have shown that Stirling refrigerators could be a promising alternative for refrigeration at 'near-ambient' temperatures (above -40 C). These theoretical statements shall be validated in an actual research project by measurements taken from a Stirling refrigerator that is optimised for this range of temperature. In this paper first measurement results of this new developed Solo 161 Stirling refrigerator will be presented. Problems are investigated by detailed measurements. Possible improvements are described. (orig.) [German] Verschiedene theoretische Untersuchungen haben gezeigt, dass Stirling-Kaeltemaschinen eine interessante Alternative fuer die Kaelteerzeugung im sog. 'umgebungsnahen' Temperaturbereich (oberhalb von -40 C) darstellen koennten. In einem derzeit laufenden Forschungsvorhaben sollen diese theoretischen Untersuchungen durch Messungen an einer fuer diesen Temperaturbereich optimierten Stirling-Kaeltemaschine ueberprueft werden. In diesem Aufsatz werden erste Messergebnisse dieser neu entwickelten Solo 161 Stirling-Kaeltemaschine praesentiert. Anhand detaillierter Messergebnisse werden Schwachstellen lokalisiert und moegliche Verbesserungsmassnahmen beschrieben. (orig.)

  5. Hydrogen isotope dynamic effects on partially reduced paramagnetic six-atom Ag clusters in low-symmetry cage of zeolite A

    Directory of Open Access Journals (Sweden)

    Amgalanbaatar Baldansuren

    2016-12-01

    Full Text Available A well-defined, monodisperse Ag6+ cluster was prepared by mild chemical treatments including aqueous ion-exchange, dehydration, oxygen calcination at 673 K and hydrogen reduction 293 K, rather than autoreduction and irradiations with γ-ray and X-ray. H2 reduction was proved as a crucial step to form the nanosize cluster with six equivalent silver atoms. Hydrogen isotope exchange and dynamics were probed by EPR and HYSCORE to provide information relevant to the cluster geometry, size, charge state and spin state. Desorption experiments result in the deuterium desorption energy of 0.78 eV from the cluster, exceeding the experimental value of 0.38 eV for the single crystal Ag(111 surface. These experiments indicate that the EPR-active clusters are in delicate equilibrium with EPR-silent clusters.

  6. Some interesting developments relating to gas dynamics in the application of the UCOR process for isotope separation

    International Nuclear Information System (INIS)

    Alant, T.G.; Schumann, W.A.

    1980-01-01

    The separating element employed in the UCOR process for uranium enrichment has a very small cut, i.e. is highly asymmetrical with respect to the UF 6 flow in the enriched and depleted streams. For the commercial exploitation of the process, the so-called helikon technique of cascading was developed. The process is dependent on the transmission of parallel streams of diffferent isotopic composition through an axial compressor without significant mixing between them. A light gas (H 2 ), which is present in large molar excess, increases the flow velocity of the process gas (UF 6 ) and hence adds to improved separation performance. The separating element not only separates isotopes but also causes appreciable separation between the process gas and the light carrier gas. The paper consists of a brief description of the helikon cascading technique followed by a comprehensive assessment of the various aspects of gas mixing in an axial compressor. Phenomena of mole mass and pressure transients which occur in the module during run-up of the compressors are also discussed. The operating characteristics of axial compressors and of the separating element produce a driving force which tends to cause mole mass and associated pressure gradients to occur circumferentially in a helikon module under static conditions. The paper includes 5 references and 10 figures

  7. Application Model for a Stirling Engine Micro-Generation System in Caravans in Different European Locations

    Directory of Open Access Journals (Sweden)

    Carlos Ulloa

    2013-02-01

    Full Text Available This article describes a simple model obtained from a commercial Stirling engine and used for heating a caravan. The Stirling engine has been tested in the lab under different electrical load conditions, and the operating points obtained are presented. As an application of the model, a series of transient simulations was performed using TRNSYS. During these simulations, the caravan is traveling throughout the day and is stationary at night. Therefore, during the night-time hours, the heating system is turned on by means of the Stirling engine. The study was performed for each month of the year in different European cities. The different heating demand profiles for different cities induce variation in the electricity production, as it has been assumed that electricity is only generated when the thermal demand requires the operation of the Stirling system. As a result, a comparison of the expected power generation in different European cities is presented.

  8. Enhanced air/fuel mixing for automotive stirling engine turbulator-type combustors

    Science.gov (United States)

    Riecke, George T.; Stotts, Robert E.

    1992-01-01

    The invention relates to the improved combustion of fuel in a combustion chamber of a stirling engine and the like by dividing combustion into primary and secondary combustion zones through the use of a diverter plate.

  9. Quantum Stirling heat engine and refrigerator with single and coupled spin systems

    Science.gov (United States)

    Huang, Xiao-Li; Niu, Xin-Ya; Xiu, Xiao-Ming; Yi, Xue-Xi

    2014-02-01

    We study the reversible quantum Stirling cycle with a single spin or two coupled spins as the working substance. With the single spin as the working substance, we find that under certain conditions the reversed cycle of a heat engine is NOT a refrigerator, this feature holds true for a Stirling heat engine with an ion trapped in a shallow potential as its working substance. The efficiency of quantum Stirling heat engine can be higher than the efficiency of the Carnot engine, but the performance coefficient of the quantum Stirling refrigerator is always lower than its classical counterpart. With two coupled spins as the working substance, we find that a heat engine can turn to a refrigerator due to the increasing of the coupling constant, this can be explained by the properties of the isothermal line in the magnetic field-entropy plane.

  10. Developing a Free-Piston Stirling Convertor for advanced radioisotope space power systems

    Science.gov (United States)

    Qiu, Songgang; Augenblick, John E.; White, Maurice A.; Peterson, Allen A.; Redinger, Darin L.; Petersen, Stephen L.

    2002-01-01

    The Department of Energy (DOE) has selected Free-Piston Stirling Convertors as a technology for future advanced radioisotope space power systems. In August 2000, DOE awarded competitive Phase I, Stirling Radioisotope Generator (SRG) power system integration contracts to three major aerospace contractors, resulting in SRG conceptual designs in February 2001. All three contractors based their designs on the Technology Demonstration Convertor (TDC) developed by Stirling Technology Company (STC) for DOE. The contract award to a single system integration contractor for Phases II and III of the SRG program is anticipated in late 2001. The first potential SRG mission is targeted for a Mars rover. This paper provides a description of the Flight Prototype (FP) Stirling convertor design as compared to the previous TDC design. The initial flight prototype units are already undergoing performance tuning at STC. The new design will be hermetically scaled and will provide a weight reduction from approximately 4.8 kg to approximately 3.9 kg. .

  11. Experimental study on the Stirling refrigerator for cooling of infrared detector

    Energy Technology Data Exchange (ETDEWEB)

    Park, S. J.; Hong, Y. J.; Kim, H. B.; Koh, D. Y. [Korea Institute of Machinery and Materials, Taejon (Korea, Republic of); Kim, J. H.; Yu, B. K. [Wooyoung, Seoul (Korea, Republic of)

    2001-07-01

    A Stirling cryocooler is relatively compact, reliable, commercially available, and uses helium as a working fluid. The FPFD Stirling cryocooler consists of two compressor pistons driven by linear motors which makes pressure waves and a pneumatically driven displacer piston with regenerator. A Free Piston and Free Displacer (FPFD) Stirling cryocooler for cooling infrared and cryo-sensors is currently under development at KIMM(Korea Institute of Machinery and Materials). In order to evaluate the feasibility of using a linear motor driving cryocooler, prototype Stirling cryocooler with a nominal cooling capacity of 0.5W at 80K was designed, fabricated and tested. The prototype has achieved no load temperature of 51K and cooling power of 0.33W.

  12. Experimental study on the Stirling refrigerator for cooling of infrared detector

    International Nuclear Information System (INIS)

    Park, S. J.; Hong, Y. J.; Kim, H. B.; Koh, D. Y.; Kim, J. H.; Yu, B. K.

    2001-01-01

    A Stirling cryocooler is relatively compact, reliable, commercially available, and uses helium as a working fluid. The FPFD Stirling cryocooler consists of two compressor pistons driven by linear motors which makes pressure waves and a pneumatically driven displacer piston with regenerator. A Free Piston and Free Displacer (FPFD) Stirling cryocooler for cooling infrared and cryo-sensors is currently under development at KIMM(Korea Institute of Machinery and Materials). In order to evaluate the feasibility of using a linear motor driving cryocooler, prototype Stirling cryocooler with a nominal cooling capacity of 0.5W at 80K was designed, fabricated and tested. The prototype has achieved no load temperature of 51K and cooling power of 0.33W

  13. Cost and price estimate of Brayton and Stirling engines in selected production volumes

    Science.gov (United States)

    Fortgang, H. R.; Mayers, H. F.

    1980-01-01

    The methods used to determine the production costs and required selling price of Brayton and Stirling engines modified for use in solar power conversion units are presented. Each engine part, component and assembly was examined and evaluated to determine the costs of its material and the method of manufacture based on specific annual production volumes. Cost estimates are presented for both the Stirling and Brayton engines in annual production volumes of 1,000, 25,000, 100,000 and 400,000. At annual production volumes above 50,000 units, the costs of both engines are similar, although the Stirling engine costs are somewhat lower. It is concluded that modifications to both the Brayton and Stirling engine designs could reduce the estimated costs.

  14. Development and Validation of Linear Alternator Models for the Advanced Stirling Convertor

    Science.gov (United States)

    Metscher, Jonathan F.; Lewandowski, Edward J.

    2015-01-01

    Two models of the linear alternator of the Advanced Stirling Convertor (ASC) have been developed using the Sage 1-D modeling software package. The first model relates the piston motion to electric current by means of a motor constant. The second uses electromagnetic model components to model the magnetic circuit of the alternator. The models are tuned and validated using test data and also compared against each other. Results show both models can be tuned to achieve results within 7 of ASC test data under normal operating conditions. Using Sage enables the creation of a complete ASC model to be developed and simulations completed quickly compared to more complex multi-dimensional models. These models allow for better insight into overall Stirling convertor performance, aid with Stirling power system modeling, and in the future support NASA mission planning for Stirling-based power systems.

  15. Novel Ring-Configuration Double-Acting Free-Piston Stirling Convertor, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA SBIR-2015 Topic S3.01 seeks to evaluate and advance Stirling convertors as a potentially more efficient alternative to the radioisotope-heated thermoelectric...

  16. Performance analysis of dish solar stirling power system; Stirling engine wo mochiita taiyonetsu hatsuden system no seino yosoku

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, K; Yamaguchi, I [Meiji University, Tokyo (Japan); Naito, Y; Momose, Y [Aisin Seiki Co. Ltd., Aichi (Japan)

    1996-10-27

    In order to estimate the performance of the dish solar Stirling power system, matching and control of each component system were studied, and the performance of the 25kWe class power system was estimated on the basis of direct solar radiation measured in Miyako island, Okinawa. Application of a Stirling engine to solar heat power generation is highly effective in spite of its small scale. The total system is composed of a converging system, heat receiver, engine/generator system and control system. As the simulation result, the generator output is nearly proportional to direct solar radiation, and the system efficiency approaches to a certain constant value with an increase in direct solar radiation. As accumulated solar radiation is large, the influence of slope error of the converging mirror is comparatively small. The optimum aperture opening ratio of the heat receiver determined on the basis of mean direct solar radiation (accumulated solar radiation/{Delta}t (simulated operation time of the system)), corresponds to the primary approximation of the opening ratio for a maximum total generated output under variable direct solar radiation. 6 refs., 6 figs., 1 tab.

  17. Integration of a wood pellet burner and a Stirling engine to produce residential heat and power

    International Nuclear Information System (INIS)

    Cardozo, Evelyn; Erlich, Catharina; Malmquist, Anders; Alejo, Lucio

    2014-01-01

    The integration a Stirling engine with a pellet burner is a promising alternative to produce heat and power for residential use. In this context, this study is focused on the experimental evaluation of the integration of a 20 kW th wood pellet burner and a 1 kW e Stirling engine. The thermal power not absorbed by the engine is used to produce hot water. The evaluation highlights the effects of pellet type, combustion chamber length and cycling operation on the Stirling engine temperatures and thermal power absorbed. The results show that the position of the Stirling engine is highly relevant in order to utilize as much as possible of the radiative heat from the burner. Within this study, only a 5 cm distance change between the Stirling engine and the pellet burner could result in an increase of almost 100 °C in the hot side of the engine. However, at a larger distance, the temperature of the hot side is almost unchanged suggesting dominating convective heat transfer from the hot flue gas. Ash accumulation decreases the temperature of the hot side of the engine after some cycles of operation when a commercial pellet burner is integrated. The temperature ratio, which is the relation between the minimum and maximum temperatures of the engine, decreases when using Ø8 mm wood pellets in comparison to Ø6 mm pellets due to higher measured temperatures on the hot side of the engine. Therefore, the amount of heat supplied to the engine is increased for Ø8 mm wood pellets. The effectiveness of the engine regenerator is increased at higher pressures. The relation between temperature of the hot side end and thermal power absorbed by the Stirling engine is nearly linear between 500 °C and 660 °C. Higher pressure inside the Stirling engine has a positive effect on the thermal power output. Both the chemical and thermal losses increase somewhat when integrating a Stirling engine in comparison to a stand-alone boiler for only heat production. The overall efficiency

  18. Commercialization possibilities of Stirling engine technology for microscale power generation in Sweden

    OpenAIRE

    Backman, Peter

    2012-01-01

    The presented master’s thesis has evaluated the possibility of commercializing a research project at the Royal Institute of Technologys (KTH) Department of Energy Technology (EGI) in Stockholm, Sweden, where a Stirling engine is used for renewable microscale power generation.  The purpose of the thesis has been to evaluate the current market situation and future prospects by composing a business plan under the working name MicroStirling. In the business plan a potential target group consistin...

  19. Chemistry and isotopic composition of precipitation and surface waters in Khumbu valley (Nepal Himalaya): N dynamics of high elevation basins.

    Science.gov (United States)

    Balestrini, Raffaella; Polesello, Stefano; Sacchi, Elisa

    2014-07-01

    We monitored the chemical and isotopic compositions of wet depositions, at the Pyramid International Laboratory (5050 ma.s.l.), and surrounding surface waters, in the Khumbu basin, to understand precipitation chemistry and to obtain insights regarding ecosystem responses to atmospheric inputs. The major cations in the precipitation were NH4(+) and Ca(2+), whereas the main anion was HCO3(-), which constituted approximately 69% of the anions, followed by NO3(-), SO4(2-) and Cl(-). Data analysis suggested that Na(+), Cl(-) and K(+) were derived from the long-range transport of marine aerosols. Ca(2+), Mg(2+) and HCO3(-) were related to rock and soil dust contributions and the NO3(-) and SO4(2-) concentrations were derived from anthropogenic sources. Furthermore, NH4(+) was derived from gaseous NH3 scavenging. The isotopic composition of weekly precipitation ranged from -1.9 to -23.2‰ in δ(18)O, and from -0.8 to -174‰ in δ(2)H, with depleted values characterizing the central part of the monsoon period. The chemical composition of the stream water was dominated by calcite and/or gypsum dissolution. However, the isotopic composition of the stream water did not fully reflect the composition of the monsoon precipitation, which suggested that other water sources contributed to the stream flow. Precipitation contents for all ions were the lowest ones among those measured in high elevation sites around the world. During the monsoon periods the depositions were not substantially influenced by anthropogenic inputs, while in pre- and post-monsoon seasons the Himalayas could not represent an effective barrier for airborne pollution. In the late monsoon phase, the increase of ionic contents in precipitation could also be due to a change in the moisture source. The calculated atmospheric N load (0.30 kg ha(-1) y(-1)) was considerably lower than the levels that were measured in other high-altitude environments. Nevertheless, the NO3(-) concentrations in the surface waters

  20. Chemistry and isotopic composition of precipitation and surface waters in Khumbu valley (Nepal Himalaya): N dynamics of high elevation basins

    International Nuclear Information System (INIS)

    Balestrini, Raffaella; Polesello, Stefano; Sacchi, Elisa

    2014-01-01

    We monitored the chemical and isotopic compositions of wet depositions, at the Pyramid International Laboratory (5050 m a.s.l.), and surrounding surface waters, in the Khumbu basin, to understand precipitation chemistry and to obtain insights regarding ecosystem responses to atmospheric inputs. The major cations in the precipitation were NH 4 + and Ca 2+ , whereas the main anion was HCO 3 − , which constituted approximately 69% of the anions, followed by NO 3 − , SO 4 2− and Cl − . Data analysis suggested that Na + , Cl − and K + were derived from the long-range transport of marine aerosols. Ca 2+ , Mg 2+ and HCO 3 − were related to rock and soil dust contributions and the NO 3 − and SO 4 2− concentrations were derived from anthropogenic sources. Furthermore, NH 4 + was derived from gaseous NH 3 scavenging. The isotopic composition of weekly precipitation ranged from − 1.9 to − 23.2‰ in δ 18 O, and from − 0.8 to − 174‰ in δ 2 H, with depleted values characterizing the central part of the monsoon period. The chemical composition of the stream water was dominated by calcite and/or gypsum dissolution. However, the isotopic composition of the stream water did not fully reflect the composition of the monsoon precipitation, which suggested that other water sources contributed to the stream flow. Precipitation contents for all ions were the lowest ones among those measured in high elevation sites around the world. During the monsoon periods the depositions were not substantially influenced by anthropogenic inputs, while in pre- and post-monsoon seasons the Himalayas could not represent an effective barrier for airborne pollution. In the late monsoon phase, the increase of ionic contents in precipitation could also be due to a change in the moisture source. The calculated atmospheric N load (0.30 kg ha −1 y −1 ) was considerably lower than the levels that were measured in other high-altitude environments. Nevertheless, the NO 3

  1. Isotopes in aquaculture research

    International Nuclear Information System (INIS)

    Ayyappan, S.; Dash, B.; Ghosh, A.S.

    1996-01-01

    The applications of isotopes in aquaculture research include areas like aquatic production process, nutrient cycles and food chain dynamics, fish nutrition, fish physiology, genetics and immunology. The radioisotopes commonly used are beta emitters. The use of different radioisotopes in aquaculture research are presented. 2 tabs

  2. The Stirling engine. Simply explained, easily constructed. 9. rev. and enl. ed.; Der Stirlingmotor. Einfach erklaert und leicht gebaut

    Energy Technology Data Exchange (ETDEWEB)

    Viebach, Dieter

    2010-07-01

    Subsequently to a easily comprehensively description of the function and characteristics of Stirling engines, the author of the book under consideration describes the construction of a model Stirling engine on the basis of clear construction drawings. A delicacy for experienced modelers: The 'amazing model', a miniature Stirling engine consisting of beverage cans, has been running with the warmth of the human hand. Even in this technically demanding model, the construction will be described accurately by detailed construction drawings.

  3. Relaxation dynamics and transformation kinetics of deeply supercooled water: Temperature, pressure, doping, and proton/deuteron isotope effects.

    Science.gov (United States)

    Lemke, Sonja; Handle, Philip H; Plaga, Lucie J; Stern, Josef N; Seidl, Markus; Fuentes-Landete, Violeta; Amann-Winkel, Katrin; Köster, Karsten W; Gainaru, Catalin; Loerting, Thomas; Böhmer, Roland

    2017-07-21

    Above its glass transition, the equilibrated high-density amorphous ice (HDA) transforms to the low-density pendant (LDA). The temperature dependence of the transformation is monitored at ambient pressure using dielectric spectroscopy and at elevated pressures using dilatometry. It is found that near the glass transition temperature of deuterated samples, the transformation kinetics is 300 times slower than the structural relaxation, while for protonated samples, the time scale separation is at least 30 000 and insensitive to doping. The kinetics of the HDA to LDA transformation lacks a proton/deuteron isotope effect, revealing that this process is dominated by the restructuring of the oxygen network. The x-ray diffraction experiments performed on samples at intermediate transition stages reflect a linear combination of the LDA and HDA patterns implying a macroscopic phase separation, instead of a local intermixing of the two amorphous states.

  4. Relaxation dynamics and transformation kinetics of deeply supercooled water: Temperature, pressure, doping, and proton/deuteron isotope effects

    Science.gov (United States)

    Lemke, Sonja; Handle, Philip H.; Plaga, Lucie J.; Stern, Josef N.; Seidl, Markus; Fuentes-Landete, Violeta; Amann-Winkel, Katrin; Köster, Karsten W.; Gainaru, Catalin; Loerting, Thomas; Böhmer, Roland

    2017-07-01

    Above its glass transition, the equilibrated high-density amorphous ice (HDA) transforms to the low-density pendant (LDA). The temperature dependence of the transformation is monitored at ambient pressure using dielectric spectroscopy and at elevated pressures using dilatometry. It is found that near the glass transition temperature of deuterated samples, the transformation kinetics is 300 times slower than the structural relaxation, while for protonated samples, the time scale separation is at least 30 000 and insensitive to doping. The kinetics of the HDA to LDA transformation lacks a proton/deuteron isotope effect, revealing that this process is dominated by the restructuring of the oxygen network. The x-ray diffraction experiments performed on samples at intermediate transition stages reflect a linear combination of the LDA and HDA patterns implying a macroscopic phase separation, instead of a local intermixing of the two amorphous states.

  5. Dynamical and many-body correlation effects in the kinetic energy spectra of isotopes produced in nuclear multifragmentation

    Science.gov (United States)

    Souza, S. R.; Donangelo, R.; Lynch, W. G.; Tsang, M. B.

    2018-03-01

    The properties of the kinetic energy spectra of light isotopes produced in the breakup of a nuclear source and during the de-excitation of its products are examined. The initial stage, at which the hot fragments are created, is modeled by the statistical multifragmentation model, whereas the Weisskopf-Ewing evaporation treatment is adopted to describe the subsequent fragment de-excitation, as they follow their classical trajectories dictated by the Coulomb repulsion among them. The energy spectra obtained are compared to available experimental data. The influence of the fusion cross section entering into the evaporation treatment is investigated and its influence on the qualitative aspects of the energy spectra turns out to be small. Although these aspects can be fairly well described by the model, the underlying physics associated with the quantitative discrepancies remains to be understood.

  6. Optimum performance characteristics of a solar-driven Stirling heat engine system

    International Nuclear Information System (INIS)

    Liao, Tianjun; Lin, Jian

    2015-01-01

    Graphical abstract: T–S diagram of the SHE cycle. - Highlights: • Based on Lagrange multiplier method, the optimal performance are investigated. • The energy balance between the absorber and the hot side of Stirling heat engine is considered. • The effects of major parameters on the optimal performance are investigated. - Abstract: A solar-driven Stirling heat engine system composed of a Stirling heat engine, a solar collector, and a heat sink is presented, in which the radiation and convection heat losses of the solar collector, the heat-leak between the thermal absorber and heat sink, the regenerative losses of the Stirling heat engine, and the energy balance between the thermal absorber and the high isothermal process of the Stirling heat engine are taken into consideration. Based on the irreversible thermodynamics and Lagrange multiplier method, the maximum power output and the corresponding optimal efficiency of the system are determined and the absorber temperature that maximizes the optimal system efficiency is calculated numerically. The influences of some system parameters such as the concentrating ratio, the volume ratio during the regenerative processes and irreversibilities of heat exchange processes on the optimal efficiency are analyzed in details. The results obtained here may provide a new idea to design practical solar-driven Stirling heat engine system

  7. New 5 kW free-piston Stirling space convertor developments

    Science.gov (United States)

    Brandhorst, Henry W., Jr.; Chapman, Peter A., Jr.

    2008-07-01

    The NASA Vision for Exploration of the moon may someday require a nuclear reactor coupled with a free-piston Stirling convertor at a power level of 30-40 kW. In the 1990s, Mechanical Technology Inc.'s Stirling Engine Systems Division (some of whose Stirling personnel are now at Foster-Miller, Inc.) developed a 25 kW free-piston Stirling Space Power Demonstrator Engine under the SP-100 program. This system consisted of two 12.5 kW engines connected at their hot ends and mounted in tandem to cancel vibration. Recently, NASA and DoE have been developing dual 55 and 80 W Stirling convertor systems for potential use with radioisotope heat sources. Total test times of all convertors in this effort exceed 120,000 h. Recently, NASA began a new project with Auburn University to develop a 5 kW, single convertor for potential use in a lunar surface reactor power system. Goals of this development program include a specific power in excess of 140 W/kg at the convertor level, lifetime in excess of five years and a control system that will safely manage the convertors in case of an emergency. Auburn University awarded a subcontract to Foster-Miller, Inc. to undertake development of the 5 kW Stirling convertor assembly. The characteristics of the design along with progress in developing the system will be described.

  8. Thermodynamic analysis of SOFC (solid oxide fuel cell)–Stirling hybrid plants using alternative fuels

    International Nuclear Information System (INIS)

    Rokni, Masoud

    2013-01-01

    A novel hybrid power system (∼10 kW) for an average family home is proposed. The system investigated contains a solid oxide fuel cell (SOFC) on top of a Stirling engine. The off-gases produced in the SOFC cycle are fed to a bottoming Stirling engine, at which additional power is generated. Simulations of the proposed system were conducted using different fuels, which should facilitate the use of a variety of fuels depending on availability. Here, the results for natural gas (NG), ammonia, di-methyl ether (DME), methanol and ethanol are presented and analyzed. The system behavior is further investigated by comparing the effects of key factors, such as the utilization factor and the operating conditions under which these fuels are used. Moreover, the effect of using a methanator on the plant efficiency is also studied. The combined system improves the overall electrical efficiency relative to that of a stand-alone Stirling engine or SOFC plant. For the combined SOFC and Stirling configuration, the overall power production was increased by approximately 10% compared to that of a stand-alone SOFC plant. System efficiencies of approximately 60% are achieved, which is remarkable for such small plant sizes. Additionally, heat is also produced to heat the family home when necessary. - Highlights: • Integrating a solid oxide fuel with a Stirling engine • Design of multi-fuel hybrid plants • Plants running on alternative fuels; natural gas, methanol, ethanol, DME and ammonia • Thermodynamic analysis of hybrid SOFC–Stirling engine plants

  9. Test Program for Stirling Radioisotope Generator Hardware at NASA Glenn Research Center

    Science.gov (United States)

    Lewandowski, Edward J.; Bolotin, Gary S.; Oriti, Salvatore M.

    2015-01-01

    Stirling-based energy conversion technology has demonstrated the potential of high efficiency and low mass power systems for future space missions. This capability is beneficial, if not essential, to making certain deep space missions possible. Significant progress was made developing the Advanced Stirling Radioisotope Generator (ASRG), a 140-W radioisotope power system. A variety of flight-like hardware, including Stirling convertors, controllers, and housings, was designed and built under the ASRG flight development project. To support future Stirling-based power system development NASA has proposals that, if funded, will allow this hardware to go on test at the NASA Glenn Research Center. While future flight hardware may not be identical to the hardware developed under the ASRG flight development project, many components will likely be similar, and system architectures may have heritage to ASRG. Thus, the importance of testing the ASRG hardware to the development of future Stirling-based power systems cannot be understated. This proposed testing will include performance testing, extended operation to establish an extensive reliability database, and characterization testing to quantify subsystem and system performance and better understand system interfaces. This paper details this proposed test program for Stirling radioisotope generator hardware at NASA Glenn. It explains the rationale behind the proposed tests and how these tests will meet the stated objectives.

  10. Developing novel peat isotope proxies from vascular plant-dominated peatlands of New Zealand to reconstruct Southern Hemisphere climate dynamics

    Science.gov (United States)

    Roland, T.; Amesbury, M. J.; Charman, D.; Newnham, R.; Royles, J.; Griffiths, H.; Ratcliffe, J.; Rees, A.; Campbell, D.; Baisden, T.; Keller, E. D.

    2017-12-01

    The Southern Annular Mode (SAM) is a key control on the strength and position of the southern westerly winds (SWW), which are a major influence on Southern Hemisphere (SH) mid- to high-latitude climate. A shift towards a more positive SAM has occurred since the 1950s, driven by ozone layer thinning and enhanced by greenhouse gas driven warming. Although these recent changes are thought to be unprecedented over the last 1000 years, the longer-term behaviour of the SAM is poorly understood. We are developing stable isotope proxies from plant cellulose in vascular plant-dominated (Empodisma spp.) peatlands in New Zealand that we hypothesise are related to changes in past temperature (δ13C) and precipitation moisture source (δ18O). The moisture source signal is driven by the balance between Southern Ocean sources (depleted δ18O) and sub-tropical sources (enriched δ18O), reflecting the relative states of SAM and the El Niño-Southern Oscillation. We aim to provide palaeoclimatic context for the recent positive trend in the SAM, and explore the long-term relationship between the SAM and ENSO, testing the contention that tropical Pacific variability is a key influence on past and future SAM variability. Terrestrial palaeoclimate records in the Southern Hemisphere are often spatially isolated and temporally fragmented. However, New Zealand is ideally placed to test such hypotheses as it registers strong correlations between SAM, temperature and precipitation, and it straddles the zone of interaction between the SWW and sub-tropical moisture sources, reflected in a strong precipitation δ18O gradient. We report data from surface samples across New Zealand and explore the spatial and temporal patterns in stable isotopes in cellulose and water that we will use to interpret the palaeoenvironmental data. Preliminary downcore data will be used to demonstrate the efficacy of this approach to reconstructing moisture sources and temperature linked to moisture source variability.

  11. Stable isotope and groundwater flow dynamics of agricultural irrigation recharge into groundwater resources of the Central Valley, California

    International Nuclear Information System (INIS)

    Davisson, M.L.; Criss, R.E.

    1995-01-01

    Intensive agricultural irrigation and overdraft of groundwater in the Central Valley of California profoundly affect the regional quality and availability of shallow groundwater resources. In the natural state, the δ 18 O values of groundwater were relatively homogeneous (mostly -7.0 ± 0.5 per-thousand), reflecting local meteoric recharge that slowly (1-3m/yr) flowed toward the valley axis. Today, on the west side of the valley, the isotope distribution is dominated by high 18 O enclosures formed by recharge of evaporated irrigation waters, while the east side has bands of low 18 O groundwater indicating induced recharge from rivers draining the Sierra Nevada mountains. Changes in δ 18 O values caused by the agricultural recharge strongly correlate with elevated nitrate concentrations (5 to >100 mg/L) that form pervasive, non-point source pollutants. Small, west-side cities dependent solely on groundwater resources have experienced increases of >1.0 mg/L per year of nitrate for 10-30 years. The resultant high nitrates threaten the economical use of the groundwater for domestic purposes, and have forced some well shut-downs. Furthermore, since >80% of modern recharge is now derived from agricultural irrigation, and because modern recharge rates are ∼10 times those of the natural state, agricultural land retirement by urbanization will severely curtail the current safe-yields and promote overdraft pumping. Such overdrafting has occurred in the Sacramento metropolitan area for ∼40 years, creating cones of depression ∼25m deep. Today, groundwater withdrawal in Sacramento is approximately matched by infiltration of low 18 O water (-11.0 per-thousand) away from the Sacramento and American Rivers, which is estimated to occur at 100-300m/year from the sharp 18 O gradients in our groundwater isotope map

  12. Isotope enrichment

    International Nuclear Information System (INIS)

    Garbuny, M.

    1979-01-01

    The invention discloses a method for deriving, from a starting material including an element having a plurality of isotopes, derived material enriched in one isotope of the element. The starting material is deposited on a substrate at less than a critical submonatomic surface density, typically less than 10 16 atoms per square centimeter. The deposit is then selectively irradiated by a laser (maser or electronic oscillator) beam with monochromatic coherent radiation resonant with the one isotope causing the material including the one istope to escape from the substrate. The escaping enriched material is then collected. Where the element has two isotopes, one of which is to be collected, the deposit may be irradiated with radiation resonant with the other isotope and the residual material enriched in the one isotope may be evaporated from the substrate and collected

  13. Stable isotopes

    International Nuclear Information System (INIS)

    Brazier, J.L.; Guinamant, J.L.

    1995-01-01

    According to the progress which has been realised in the technology of separating and measuring isotopes, the stable isotopes are used as preferable 'labelling elements' for big number of applications. The isotopic composition of natural products shows significant variations as a result of different reasons like the climate, the seasons, or their geographic origins. So, it was proved that the same product has a different isotopic composition of alimentary and agriculture products. It is also important in detecting the pharmacological and medical chemicals. This review article deals with the technology, like chromatography and spectrophotometry, adapted to this aim, and some important applications. 17 refs. 6 figs

  14. Isotope separation

    International Nuclear Information System (INIS)

    Bartlett, R.J.; Morrey, J.R.

    1978-01-01

    A method and apparatus is described for separating gas molecules containing one isotope of an element from gas molecules containing other isotopes of the same element in which all of the molecules of the gas are at the same electronic state in their ground state. Gas molecules in a gas stream containing one of the isotopes are selectively excited to a different electronic state while leaving the other gas molecules in their original ground state. Gas molecules containing one of the isotopes are then deflected from the other gas molecules in the stream and thus physically separated

  15. Design and Fabrication of a 5-kWe Free-Piston Stirling Power Conversion System

    Science.gov (United States)

    Chapman, Peter A.; Walter, Thomas J.; Brandhorst, Henry W., Jr.

    2008-01-01

    Progress in the design and fabrication of a 5-kWe free-piston Stirling power conversion system is described. A scaled-down version of the successful 12.5-kWe Component Test Power Converter (CTPC) developed under NAS3-25463, this single cylinder prototype incorporates cost effective and readily available materials (steel versus beryllium) and components (a commercial linear alternator). The design consists of a displacer suspended on internally pumped gas bearings and a power piston/alternator supported on flexures. Non-contacting clearance seals are used between internal volumes. Heat to and from the prototype is supplied via pumped liquid loops passing through shell and tube heat exchangers. The control system incorporates several novel ideas such as a pulse start capability and a piston stroke set point control strategy that provides the ability to throttle the engine to match the required output power. It also ensures stable response to various disturbances such as electrical load variations while providing useful data regarding the position of both power piston and displacer. All design and analysis activities are complete and fabrication is underway. Prototype test is planned for summer 2008 at Foster-Miller to characterize the dynamics and steady-state operation of the prototype and determine maximum power output and system efficiency. Further tests will then be performed at Auburn University to determine start-up and shutdown characteristics and assess transient response to temperature and load variations.

  16. Study on the flow nonuniformity in a high capacity Stirling pulse tube cryocooler

    Science.gov (United States)

    You, X.; Zhi, X.; Duan, C.; Jiang, X.; Qiu, L.; Li, J.

    2017-12-01

    High capacity Stirling-type pulse tube cryocoolers (SPTC) have promising applications in high temperature superconductive motor and gas liquefaction. However, with the increase of cooling capacity, its performance deviates from well-accepted one-dimensional model simulation, such as Sage and Regen, mainly due to the strong field nonuniformity. In this study, several flow straighteners placed at both ends of the pulse tube are investigated to improve the flow distribution. A two-dimensional model of the pulse tube based on the computational fluid dynamics (CFD) method has been built to study the flow distribution of the pulse tube with different flow straighteners including copper screens, copper slots, taper transition and taper stainless slot. A SPTC set-up which has more than one hundred Watts cooling power at 80 K has been built and tested. The flow straighteners mentioned above have been applied and tested. The results show that with the best flow straightener the cooling performance of the SPTC can be significantly improved. Both CFD simulation and experiment show that the straighteners have impacts on the flow distribution and the performance of the high capacity SPTC.

  17. Isotopes in environmental research

    International Nuclear Information System (INIS)

    Bowen, G.; Rozanski, K.; Vose, P.

    1990-01-01

    Radioactive and stable isotopes have long been considered a very efficient tool for studying physical and biological aspects of how the global ecosystem functions. Their applications in environmental research are numerous, embracing research at all levels. This article looks at only a few of the approaches to environmental problems that involve the use of isotopes. Special attention is given to studies of the Amazon Basin. Environmental isotopes are very efficient tools in water cycle studies. Tritium, a radioactive tracer, is especially useful in studying dynamics of water movement in different compartments of the hydrosphere, both on the local and global scales. Heavy stable isotopes of hydrogen and oxygen (deuterium and oxygen-18) provide information about steady-state characteristics of the water cycle. Isotope methods, some relatively new, have a major role in site-specific studies. Some indicative examples include: Studying turnover of organic matter. Changes in the carbon-13/carbon-12 isotopic ratio of organic matter were used to determine the respective contributions of organic carbon derived from forest and pasture. Studying biological nitrogen fixation. One of the ways nitrogen levels in soil can be maintained for productivity is by biological nitrogen fixation. Studying nitrogen availability and losses. The experimental use of nitrogen-15 is invaluable for defining losses of soil nitrogen to the atmosphere and to groundwater. Studies can similarly be done with stable and radioactive sulphur isotopes. This article indicates some potential uses of isotopes in environmental research. While the major problem of global climate change has not been specifically addressed here, the clearing of the Amazon forest, one focus of the IAEA's environmental programme, may have serious consequences for the global climate. These include substantial reduction of the amount of latent heat transported to the regions outside the tropics and acceleration of the greenhouse

  18. Effects of sample injection amount and time-of-flight mass spectrometric detection dynamic range on metabolome analysis by high-performance chemical isotope labeling LC-MS.

    Science.gov (United States)

    Zhou, Ruokun; Li, Liang

    2015-04-06

    The effect of sample injection amount on metabolome analysis in a chemical isotope labeling (CIL) liquid chromatography-mass spectrometry (LC-MS) platform was investigated. The performance of time-of-flight (TOF) mass spectrometers with and without a high-dynamic-range (HD) detection system was compared in the analysis of (12)C2/(13)C2-dansyl labeled human urine samples. An average of 1635 ± 21 (n = 3) peak pairs or putative metabolites was detected using the HD-TOF-MS, compared to 1429 ± 37 peak pairs from a conventional or non-HD TOF-MS. In both instruments, signal saturation was observed. However, in the HD-TOF-MS, signal saturation was mainly caused by the ionization process, while in the non-HD TOF-MS, it was caused by the detection process. To extend the MS detection range in the non-HD TOF-MS, an automated switching from using (12)C to (13)C-natural abundance peaks for peak ratio calculation when the (12)C peaks are saturated has been implemented in IsoMS, a software tool for processing CIL LC-MS data. This work illustrates that injecting an optimal sample amount is important to maximize the metabolome coverage while avoiding the sample carryover problem often associated with over-injection. A TOF mass spectrometer with an enhanced detection dynamic range can also significantly increase the number of peak pairs detected. In chemical isotope labeling (CIL) LC-MS, relative metabolite quantification is done by measuring the peak ratio of a (13)C2-/(12)C2-labeled peak pair for a given metabolite present in two comparative samples. The dynamic range of peak ratio measurement does not need to be very large, as only subtle changes of metabolite concentrations are encountered in most metabolomic studies where relative metabolome quantification of different groups of samples is performed. However, the absolute concentrations of different metabolites can be very different, requiring a technique to provide a wide detection dynamic range to allow the detection of as

  19. Comparison of water-use efficiency estimates based on tree-ring carbon isotopes with simulations of a dynamic vegetation model

    Science.gov (United States)

    Saurer, Matthias; Renato, Spahni; Fortunat, Joos; David, Frank; Kerstin, Treydte; Rolf, Siegwolf

    2015-04-01

    Tree-ring d13C-based estimates of intrinsic water-use efficiency (iWUE, reflecting the ratio of assimilation A to stomatal conductance gs) generally show a strong increase during the industrial period, likely associated with the increase in atmospheric CO2. However, it is not clear, first, if tree-ring d13C-derived iWUE-values indeed reflect actual plant and ecosystem-scale variability in fluxes and, second, what physiological changes were the drivers of the observed iWUE increase, changes in A or gs or both. To address these questions, we used a complex dynamic vegetation model (LPX) that combines process-based vegetation dynamics with land-atmosphere carbon and water exchange. The analysis was conducted for three functional types, representing conifers, oaks, larch, and various sites in Europe, where tree-ring isotope data are available. The increase in iWUE over the 20th century was comparable in LPX-simulations as in tree-ring-estimates, strengthening confidence in these results. Furthermore, the results from the LPX model suggest that the cause of the iWUE increase was reduced stomatal conductance during recent decades rather than increased assimilation. High-frequency variation reflects the influence of climate, like for example the 1976 summer drought, resulting in strongly reduced A and g in the model, particularly for oak.

  20. MANUFACTURING AND TESTING OF A V-TYPE STIRLING ENGINE

    Directory of Open Access Journals (Sweden)

    B. Demir

    2012-01-01

    Full Text Available In this study, a V-type Stirling engine with 163 cc total swept volume was designed and manufactured. Air was used as working fluid. Performance tests were conducted at the range of 1-3 bar charge pressure and within the range of hot source temperature 700-1050 °C. Experimental results are given. Variation of engine power and torque with hot source temperature at various air charge pressure are tested. Also variation of engine torque with engine speed for different air charge pressure are tested. According to experimental analysis, the maximum engine power was obtained as 21.334 W at 1050 ˚C hot source temperature and 1.5 bars charge pressure.