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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Communication: Nanoscale ion fluctuations in Nafion polymer electrolyte

Ion conduction mechanisms and the nanostructure of ion conduction networks remain poorly understood in polymer electrolytes which are used as proton-exchange-membranes (PEM) in fuel cell applications. Here we study nanoscale surface-potential fluctuations produced by Brownian ion dynamics in thin films of low-hydration Nafion™, the prototype PEM. Images and power spectra of the fluctuations are used to derive the local conductivity-relaxation spectrum, in order to compare with bulk behavior and hopping-conductivity models. Conductivity relaxation-times ranged from hours to milliseconds, depending on hydration and temperature, demonstrating that the observed fluctuations are produced by water-facilitated hydrogen-ion hopping within the ion-channel network. Due to the small number of ions probed, non-Gaussian statistics of the fluctuations can be used to constrain ion conduction parameters and mechanisms.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Effect of formation temperature on properties of graphite/stannum composite for bipolar plate

Bipolar plates are key components in Proton Exchange Membrane (PEM) fuel cells. They carry current away from the cell and withstand the clamping force of the stack assembly. Therefore, PEM fuel cell bipolar plates must have high electrical conductivity and adequate mechanical strength, in addition to being light weight and low cost in terms of both applicable materials and production methods. In this research, the raw materials used to fabricate the high performance bipolar plate are Graphite (Gr), Stannum (Sn) and Polypropylene (PP). All materials used was in powder form and Gr and Sn act as fillers and the PP acts as binder. The ratio of fillers (Gr/Sn) and binder (PP) was fixed at 80:20. For the multi-conductive filler, small amount of Sn, which is 10 up to 20wt% (from the total weight of fillers 80%) have been added into Gr/Sn/PP composite. The fillers were mixed by using the ball mill machine. The second stage of mixing process between the mixer of fillers and binder is also carried out by using ball mill machine before the compaction process by the hot press machine. The effect of formation temperatures (160°C-170°C) on the properties of Gr/Sn/PP composite had been studied in detail, especially the electrical conductivity, bulk density, hardness and microstructure analysis of Gr/Sn/PP composite. The result shows that there are significant improvement in the electrical conductivity and bulk density, which are exceeding the US-DoE target with the maximum value of 265.35 S/cm and 1.682g/cm{sup 3} respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2016

A high performance neutron powder diffractometer at 3 MW Triga Mark-II research reactor in Bangladesh

A high performance neutron diffractometer called Savar Neutron Diffractometer (SAND) was built and installed at radial beam port-2 of TRIGA Mark II research reactor at AERE, Savar, Dhaka, Bangladesh. Structural studies of materials are being done by this technique to characterize materials crystallograpohically and magnetically. The micro-structural information obtainable by neutron scattering method is very essential for determining its technological applications. This technique is unique for understanding the magnetic behavior in magnetic materials. Ceramic, steel, electronic and electric industries can be benefited from this facility for improving their products and fabrication process. This instrument consists of a Popovicimonochromator with a large linear position sensitive detector array. The monochromator consists of nine blades of perfect single crystal of silicon with 6 mm thickness each. The monochromator design was optimized to provide maximum flux on 3 mm diameter cylindrical sample with a relatively flat angular dependence of resolution. Five different wave lengths can be selected by orienting the crystal at various angles. A sapphire filter was used before the primary collimator to minimize the first neutron. The detector assembly is composed of 15 linear position sensitive proportional counters placed at either 1.1 m or 1.6 m from the sample position and enclosed in a air pad supported high density polythene shield. Position sensing is obtained by charge division using 1-wide NIM position encoding modules (PEM). The PEMs communicate with the host computer via USB. The detector when placed at 1.1 m, subtends 30° (2θ) at each step and covers 120° in 4 steps. When the detector is placed at 1.6 m it subtends 20° at each step and covers 120° in 6 steps. The instrument supports both low and high temperature sample environment. The instrument supports both low and high temperature sample environment. The diffractometer is a state-of-the art technology for diffraction study in our country.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Tokamak-independent software analysis suite for multi-spectral line-polarization MSE diagnostics

A tokamak-independent analysis suite has been developed to process data from Motional Stark Effect (mse) diagnostics. The software supports multi-spectral line-polarization mse diagnostics which simultaneously measure emission at the mse σ and π lines as well as at two "background" wavelengths that are displaced from the mse spectrum by a few nanometers. This analysis accurately estimates the amplitude of partially polarized background light at the σ and π wavelengths even in situations where the background light changes rapidly in time and space, a distinct improvement over traditional "time-interpolation" background estimation. The signal amplitude at many frequencies is computed using a numerical-beat algorithm which allows the retardance of the mse photo-elastic modulators (pem's) to be monitored during routine operation. It also allows the use of summed intensities at multiple frequencies in the calculation of polarization direction, which increases the effective signal strength and reduces sensitivity to pem retardance drift. The software allows the polarization angles to be corrected for calibration drift using a system that illuminates the mse diagnostic with polarized light at four known polarization angles within ten seconds of a plasma discharge. As a result, the software suite is modular, parallelized, and portable to other facilities.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2016

A review on the performance and modelling of proton exchange membrane fuel cells

Proton Exchange Membrane Fuel Cells (PEMFC), are energy efficient and environmentally friendly alternative to conventional energy conversion for various applications in stationary power plants, portable power device and transportation. PEM fuel cells provide low operating temperature and high-energy efficiency with near zero emission. A PEM fuel cell is a multiple distinct parts device and a series of mass, energy, transport through gas channels, electric current transport through membrane electrode assembly and electrochemical reactions at the triple-phase boundaries. These processes play a decisive role in determining the performance of the Fuel cell, so that studies on the phenomena of gas flows and the performance modelling are made deeply. This paper gives a comprehensive overview of the state of the art on the Study of the phenomena of gas flow and performance modelling of PEMFC.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Fuel cells, batteries and super-capacitors stand-alone power systems management using optimal/flatness based-control

In this work, an optimal control (under constraints) based on the Pontryagin’s maximum principle is used to optimally manage energy flows in a basic PEM (Proton Exchange Membrane) fuel cells system associated to lithium-ion batteries and supercapacitors through a common DC bus having a voltage to stabilize using the differential flatness approach. The adaptation of voltage levels between different sources and load is ensured by use of three DC-DC converters, one boost connected to the PEM fuel cells, while the two others are buck/boost and connected to the lithiumion batteries and supercapacitors. The aim of this paper is to develop an energy management strategy that is able to satisfy the following objectives: Impose the power requested by a habitat (representing the load) according to a proposed daily consumption profile, Keep fuel cells working at optimal power delivery conditions, Maintain constant voltage across the common DC bus, Stabilize the batteries voltage and stored quantity of charge at desired values given by the optimal control. Results obtained under MATLAB/Simulink environment prove that the cited objectives are satisfied, validating then, effectiveness and complementarity between the optimal and flatness concepts proposed for energy management. Note that this study is currently in experimentally validation within MSE Laboratory.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2021

Improved motional Stark effect signal processing using fast Fourier transform spectral analysis

A Fast Fourier Transform (FFT) based method has been developed, which improves the frequency response of the Motional Stark Effect (MSE) system by about a factor of 10 over the conventional analog lock-in method. The method uses fits to rigorously derived analytic expressions for the FFT spectral components of the MSE signal to accurately obtain the amplitudes and phases of the 2f1 and 2f2 photo-elastic modulator (PEM) frequencies that encode the polarization angle. Since no frequency filtering is used in the FFT method, the frequency response is limited by fundamental measurement properties: the frequency response of the detector, photon statistics, sample rate, and the ability to resolve the spectral components. In contrast, the frequency response of the analog lock-in is limited by a low pass filter with a cutoff of around 500 Hz. In the case of the DIII-D MSE system, the output of the photo-multiplier tube detector was sampled at 500 kHz and FFTs with as few as 100 points were used to obtain the amplitudes of the 2f1 and 2f2 PEM frequency components. This corresponds to a frequency response of 5 kHz, about ten times faster than the analog lock-in amplifier system. Details of the FFT method will be presented and compared to those of the analog lock-in system.

Makowski, M. A.↗
DOE OSTI2022

Performance and Durability of Proton Exchange Membrane Vapor-Fed Unitized Regenerative Fuel Cells

With a growing demand for electricity, clean hydrogen production and usage can be an asset not only to mitigate emissions but for long-term energy storage as well. Hydrogen gas, a high-density energy carrier, can be made through electrolysis in charging mode and generate electricity via a fuel cell in discharging mode in a unitized regenerative fuel cell (URFC). While URFCs reduce cost by combining the charging and discharging modes into a singular device, switching between modes becomes burdensome, and water management is a major challenge. One way to mitigate these issues is to operate the entire system in the vapor phase. Vapor-phase operation simplifies the physics of the system but will introduce losses within the system, primarily ohmic and mass transport during the charging mode. In this study, we explore the performance of a Proton-Exchange-Membrane (PEM)-URFC under vapor-phase conditions and the impact of different PEMs, feed gases, and relative humidity on the performance and durability. By tailoring operating conditions and membrane, the vapor-URFC achieves a roundtrip efficiency of 42% and a lifetime of 50,000 accelerated stress test cycles for fully humidified feeds. Discussion of vapor-URFC for energy storage and extensions to look at various applications shows the promise of this technology.

25 ENERGY STORAGE↗
DOE OSTI2024

Mechanical Characterization of Electrolyzer Membranes and Components Under Compression

Proton-exchange membrane (PEM) water electrolysis is a promising technology for producing clean hydrogen by electrochemically splitting water when paired with renewable energy sources. A major roadblock to improving electrolyzer durability is the mechanical degradation of the cell components, which requires an understanding of their mechanical response under device-relevant conditions. However, there is a lack of studies on the mechanical characterization of the PEM and other components, as well as and their interactions. This study aims to address this gap by using a custom-designed testing apparatus to investigate the mechanics of electrolyzer components in uniaxial compression at 25 and 80 °C. Findings show stress-strain response of components have a varying degree of nonlinearity owing to their distinct deformation mechanisms and morphologies, from porous structures to polymers. These results are used to develop an expression for compressive stress-strain response of Nafion membranes and then analyze the deformation of components under applied pressure by using a 1-D spring network model of cell assembly. This work provides a new understanding of mechanical responses of the electrolyzer membrane and cell components, which can help assess material design and cell assembly strategies for improved electrolyzer durability.

08 HYDROGEN↗
DOE OSTI2026

FC-PLACER (Fuel Cell Plant Layout and Cost Estimation Resource) [SWR-26-027]

The Fuel Cell Plant Layout and Cost Estimation Resource (FC-PLACER) is a tool to perform a footprint and cost analysis for hydrogen fuel cell based power plants. This analysis tool provides a comprehensive design and cost assessment for a 100-MW stationary PEM fuel cell power plant, utilizing specifications from commercially available PEM fuel cell modules originally designed for heavy-duty vehicle applications. Additionally, the tool offers flexibility, enabling adaptation to various capacity requirements or plant configurations and facilitating the evaluation of system layout and overnight costs. In particular, it includes a detailed accounting of balance of plant material and labor costs and enables a precise estimate of plant spatial footprint.

Reznicek, Evan [National Laboratory of the Rockies↗
DOE OSTI2014

Process Guide to Update Performance Values

This document describes the process for updating the PATRIOT database with new performance values and restarting the PATRIOT Server with the new updates. This process was not documented for previous releases of PEM. It is not expected that external users will undertake this process. This process is described in detail here to support the IV&V and accreditation of PEM release 1.3.0.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2014

Patriot Viewer User Guide (V.1.3.0)

Patriot Viewer is a component of PEM 1.3.0 that lets an analyst visualize the routes generated by PATRIOT, the PATRIOT transportation network, and global nuclear defense architecture (GNDA) assets. Patriot Viewer satisfies two requirement thresholds from the PEM Requirements Document (March 3, 2014).

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2014

Novel Electrolyzer Applications: Providing More Than Just Hydrogen

Hydrogen can be used for many different applications and can be integrated into many different system architectures. One of the methods for producing the hydrogen is to use an electrolyzer. This work explores the flexibility of electrolyzers to behave as responsive loads. Experimental tests were performed for a proton exchange membrane (PEM) and an alkaline electrolyzer to assess the operational flexibility of electrolyzers to behave as responsive loads. The results are compared to the operational requirements to participate in end-user facility energy management, transmission and distribution system support, and wholesale electricity market services. Electrolyzers begin changing their electricity demand within milliseconds of a set-point change. The settling time after a set-point change is on the order of seconds. It took 6.5 minutes for the PEM unit to execute a cold start and 1 minute to turn off. In addition, a frequency disturbance correction test was performed and electrolyzers were able to accelerate the speed that the grid frequency can be restored. Electrolyzers acting as demand response devices can respond sufficiently fast and for a long enough duration to participate in all of the applications explored. Furthermore, electrolyzers can be operated to support a variety of applications while also providing hydrogen for industrial processes, transportation fuel, or heating fuel. Additionally, favorable operating properties and a variety of potential system architectures showcase the flexibility of electrolyzer systems.

08 HYDROGEN↗
DOE OSTI2015

Durability Improvements Through Degradation Mechanism Studies

The durability of polymer electrolyte membrane (PEM) fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. By investigating cell component degradation modes and defining the fundamental degradation mechanisms of components and component interactions, new materials can be designed to improve durability. To achieve a deeper understanding of PEM fuel cell durability and component degradation mechanisms, we utilize a multi-institutional and multi-disciplinary team with significant experience investigating these phenomena.

08 HYDROGEN↗
DOE OSTI2017

Final CRADA Report for Small Business Voucher (SBV) Pilot Project with TreadStone Technologies, Inc. – Novel Coating for Fuel Cell Metal Bipolar Plates

Light-weight metal is the preferred material for bipolar plate in the automotive proton exchange membrane (PEM) fuel cell stack. The challenge using metal bipolar plates is the high surface electrical contact resistance and the poor corrosion resistance in PEM fuel cell operation conditions. This SBV project involved specialized capabilities and expertise at Los Alamos National Laboratory (LANL) and Oak Ridge National Laboratory (ORNL) supporting TreadStone Technologies, Inc. and included ex-situ and in-situ drive-cycle tests that incorporated coated metallic bipolar plates (LANL tasks) and analysis of the surface chemistry and microstructure of coatings on stainless steel substrates (ORNL tasks).

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2018

Performance enhancement of a polymer-electrolyte membrane H2O and CO2 co-electrolysis system for the production of syngas

Co-electrolysis of water and CO 2 to produce hydrogen and CO would provide an alternative pathway to making chemicals and fuels. The process could provide a way to use excess renewable electricity, or could be coupled to nuclear or carbon-based power generation. Opus 12 has overcome barriers to using a proton exchange membrane (PEM) reactor for this reaction by modifying the cathode catalyst layer to enhance simultaneous electrochemical H 2 production and CO 2 reduction. Current reactor performance metrics in terms of selectivity, current density, and applied voltage meet or exceed internal targets. However, the cell lifetime must be extended for a commercial product to be feasible. Through this H2@Scale project, we propose to work with the Weber Group at LBNL to diagnose performance decay mechanisms that currently limit the lifetime of the electrochemical syngas generator. LBNL is host to a number of advanced PEM diagnostic tools and lab scientists have unique experience in exploring performance and lifetime tradeoffs at the component to cell scales. Using the results of this study, the identified limiting mechanisms will be mitigated through improved cell and catalyst design.

10 SYNTHETIC FUELS↗
DOE OSTI2018

Investigation of continuous Pt-monolayer deposition method on stable non-noble metals and other stable materials (Final Report)

The objective of the project is for BNL to investigate the method of depositing continuous Pt monolayer on non-noble metals and other stable materials under PEM fuel cell operating condition. The motivation of this research is to develop a novel Pt monolayer catalyst for O 2 reduction reaction. This leads to ultra-low Pt loading (<0.1 mg/cm 2 ) for PEM fuel cell catalyst. The deposited Pt-monolayer will be tested to determine their activity and stability under potential cycling conditions. Project involves exploring approaches to increase the catalyst's activity and stability against oxidation under fuel cell operating conditions.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2020

Coordinated Multiscale Modeling and Synthesis of Novel Nanostructured Composite Membranes for Solar Fuels Generation (Final Report)

Generation of carbon-based liquid fuels from reduction of CO 2 using solar energy requires the development of improved membranes that provide good ionic conductivity and mechanical properties while minimizing the crossover of gases and reduction products. Using closely coordinated multiscale modeling, synthesis and characterization studies we propose to investigate and develop novel nanostructured composite membranes with applications to conversion of carbon dioxide to storable chemical fuels. The envisioned proton exchange membranes (PEMs) will be based on a support of self- assembling polymer-modified nanoparticles with controllable porosity and tortuosity. The use of a nanoparticle support will provide control of transport and mechanical properties of the membranes. Tuning the copolymer modification of nanoparticles (polymer architectures, brush grafting density) will allow to optimize the ion (proton) transport via the Grotthuss mechanism through narrow hydrated channels while minimizing crossover of gases and reaction products due to the high density of the grafted brush and use of a non-ionic conducting glassy polymers to fill spaces between polymer-grafted nanoparticles. In Phase I synthesis of the copolymers and their attachment to the nanoparticle support will be guided by multiscale simulations that include atomistic molecular dynamics and continuum-level transport simulations. The former will include reactive and non-reactive atomistic simulations that will provide key insight into nanoscale polymer morphology and ion/molecular transport mechanisms need to optimize the copolymer structure. The latter will provide insight into the role of nanoparticle self-assembly on the global transport of ionic and molecular species. The proton conduction and CO 2 /methanol permeability of the membranes will be experimentally characterized as well as simulated and will be correlated with morphology and polymer structure. Prototypes of optimal membranes will be fabricated and characterized at the end of the project. Successful development of improved nanostructured composite PEMs and demonstration of the simulation-guided materials-by-design paradigm will result in our ability to design and synthesize membranes for a wide variety of solar fuels generation and related electrochemical applications.

14 SOLAR ENERGY↗