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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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A series of multicyclic hydrocarbons were synthesized in high yield and under mild conditions from 2,5-hexanedione, cyclohexanone and cyclopentanone, on a scale of 200 g.
Lanthanum strontium cobaltite (LSCo) is considered as a good candidate cathode contact material for solid oxide fuel cells, due to high electrical conductivity. However, LSCo has a very large coefficient of thermal expansion (CTE) than the cells and metallic interconnects. As a result, poor mechanical stability is expected during thermal cycling. To minimize the CTE mismatch, we investigate a composite approach involving mixing LSCo with an inert material of low CTE, such as mullite at volume fractions from 0.1 to 0.4. Composite’s CTE shows a decreasing trend with increasing mullite volume fractions, and is consistent with model predictions. X-ray powder diffraction analysis of sintered LSCo/mullite composites exhibits no presence of other phases for samples aged for 500h at 800oC, indicating chemical compatibility. Electrical conductivity by a 4-pt method shows a decreasing trend with increasing mullite content. Contact strength of as-sintered and thermally cycled samples show that only the composite with 0.4 volume fraction has a measurable strength; the other composites have no strength. Overall, the composite approach is demonstrated in the LSCo/mullite system to lower the CTE and hence achieve thermal cycle stability. The addition of the inert phase to the LSCo matrix; however, also reduces the electrical conductivity.
Ionic liquid (IL) additives to both traditional and advanced oxygen reduction reaction (ORR) electrocatalysts have yielded remarkable improvements in catalyst performance and durability. However, incorporating ILs or IL-modified catalysts into the electrodes of a proton exchange membrane fuel cell (PEMFC) membrane electrode assembly (MEA) has proven to be challenging. Sulfonated poly(ionic liquid) block copolymers (S-PILBCP) present an opportunity to incorporate IL functionality directly into the ionomer, orthogonal to protonic conductivity. Here, we use a rotating disc electrode (RDE) to characterize the interface between a S-PILBCP and Pt catalyst in comparison to Nafion. Catalyst thin films prepared with S-PILBCP show an 80% improvement in the ORR activity over those containing Nafion. Thin films of S-PILBCP also show a significantly reduced degree of poisoning sulfonate adsorption on a Pt(111) surface in comparison to Nafion. Furthermore, these half-cell results provide useful insights that help to highlight the source of the impact of the S-PILBCP on PEMFC MEA performance.
This paper investigates the optimal crankshaft motion for an opposed piston (OP) engine in a novel hybrid architecture to maximize fuel efficiency. The OP engine was selected for this work due to its inherent thermodynamic benefits and the balanced nature of the engine which can achieve downsizing through reducing the number of cylinders rather than the individual cylinder volume. The typical geartrain required on an OP engine was exchanged for two electric motors, reducing friction loss and decoupling the crankshafts. Using the motors to control the crankshaft motion profiles, this architecture introduces capabilities to dynamically vary compression ratio, combustion volume, and scavenging dynamics. To leverage these opportunities, an optimization scheme was developed utilizing nonlinear optimization of a 0-D model to compute the crankshaft motion profile that maximizes the work generated by the system. This optimization was then iteratively coupled with a high fidelity model which supplies the cylinder flow boundary conditions. This iterative approach reduces the model complexity used in the optimal control problem (OCP) while capturing the gas exchange dynamics critical to the 2-stroke cycle of the OP engine. By using the rate of change of motor torque as the input to the OCP, the torque fluctuation in a single cycle can be limited to ensure tracking feasibility. The results show crankshaft velocity slows during the compression stroke and conversely accelerates during the expansion stroke, reducing the peak motor torque required for control and thus reducing the motor losses. The extended residence time at top dead center, however, leads to an increase in heat transfer, illustrating the trade-off between the work extraction efficiency and the indicated engine efficiency.
Ducted fuel injection (DFI) is a strategy to improve fuel/charge-gas mixing in direct-injection compression-ignition engines. DFI involves injecting fuel along the axis of a small tube in the combustion chamber, which promotes the formation of locally leaner mixtures in the autoignition zone relative to conventional diesel combustion. Previous work has demonstrated that DFI is effective at curtailing engine-out soot emissions across a wide range of operating conditions. This study extends previous investigations, presenting engine-out emissions and efficiency trends between ducted two-orifice and ducted four-orifice injector tip configurations. For each configuration, parameters investigated include injection pressure, injection duration, intake manifold pressure, intake manifold temperature, start of combustion timing, and intake-oxygen mole fraction. For both configurations and across all parameters, DFI reduced engine-out soot emissions compared to conventional diesel combustion, with little effect on other emissions and engine efficiency. Emissions trends for both configurations were qualitatively the same across the parameters investigated. The four-duct configuration had higher thermal efficiency and indicated-specific engine-out nitrogen oxide emissions but lower indicated-specific engine-out hydrocarbon and carbon monoxide emissions than the two-duct assembly. Both configurations achieved indicated-specific engine-out emissions for both soot and nitrogen oxides that comply with current on- and off-road heavy-duty regulations in the United States without exhaust-gas aftertreatment at an intake-oxygen mole fraction of 12%. High-speed in-cylinder imaging of natural soot luminosity shows that some conditions include a second soot-production phase late in the cycle. The probability of these late-cycle events is sensitive to both the number of ducted sprays and the operating conditions.
Innovators/Researchers at Los Alamos National Laboratory have developed an electrode composition that improves fuel cell performance under anhydrous conditions above 100°C. It has demonstrated great durability in humidified conditions under 100°C as well. It holds promise for use in fuel cells for heavy duty vehicles while retaining utility for portable and stationary power applications. In coming years this flexibility may be a breakthrough improvement over conventional compositions.
This report presents a comprehensive framework for estimating diesel fuel consumption and prices at open-pit mines in the United States. The framework includes transparent methods for calculating site-level diesel energy use when direct reporting is unavailable, and a structured confidence evaluation for each method. The framework is demonstrated to estimate current diesel consumption at 21 open-pit mines in the United States. Initial findings support ongoing efforts to strengthen the competitiveness and security of the U.S. industrial base by supporting data-driven supply chain analysis and decision-making, improved transparency in mining sector energy use, and targeted deployment of energy innovation and cost-reduction strategies. Future updates to the dataset—coupled with expanded data transparency and method validation—will help ensure that the findings remain relevant as the sector continues to evolve.
Fossil fuel power plants are complex systems containing multiple components that require periodic health monitoring. Failures in these systems can lead to increased downtime for the plant, reduction of power, and significant cost for repairs. Inspections of the plant’s superheater tubes are typically manual, laborious, and extremely time-consuming. This is due to their small diameter size (between 1.3 and 7.6 cm) and the coiled structure of the tubing. In addition, the tubes are often stacked close to each other, limiting access for external inspection. This paper presents the development and testing of an electrically powered pipe crawler that can navigate inside 5 cm diameter tubes and provide an assessment of their health. The crawler utilizes peristaltic motion within the tubes via interconnected modules for gripping and extending. The modular nature of the system allows it to traverse through straight sections and multiple 90° and 180° bends. Additional modules in the system include an ultrasonic sensor for tube thickness measurements, as well as environmental sensors, a light detecting and ranging (LiDAR) sensor, and camera. Furthermore, these modules utilize a gear system that allows for 360° rotation and provides a means to inspect the entire internal circumference of the tubes.
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Argonne National Laboratory performed calculations in order to determine the viability of various mode of operation and operating conditions for the reactor designed by Elysium Industry. The reactor description, operating conditions, startup fuel composition, and other relevant information were provided by Elysium to Argonne. The tools currently available at Argonne were used to perform the calculations and provide an assessment for the various cases agreed upon. The results were shared with Elysium.
The aim for storage of spent nuclear fuel (SNF) either in wet or in dry storage systems is to ensure general safety objective s are met throughout a desired storage period. Staff at the Savannah River National Laboratory (SRNL), in collaborations with partners at other national laboratories, industry research organizations, and the University of South Carolina (UofSC), have performed materials aging testing and analyses, and have established nuclear materials aging management programs to support extended periods of safe storage of research reactor (RR) SNF and of commercial power reactor (PR) SNF pending ultimate disposal. Several example challenges include susceptibility of aluminum SNF from research reactors to corrosion in poor quality water (wet storage). In dry storage, aluminum SNF can release hydrogen via radiolysis of the hydrated oxides on the aluminum cladding. Austenitic stainless steel canisters used for dry storage are susceptible to chloride-induced stress corrosion cracking (outside-in attack) that threaten the confinement boundary provided by the canister. This paper further describes these challenges, among others, and the formulated solutions to support extended safe storage of SNF.
Intermediate temperature solid oxide fuel cells (IT-SOFCs) are cost-effective and efficient energy conversion systems. Here, the sluggish oxygen reduction reaction (ORR) and the degradation of cathodes are critical challenges to the commercialization of IT-SOFCs. Here, a highly efficient multiphase (MP) catalyst coating, consisting of Ba 1–x Co 0.7 Fe 0.2 Nb 0.1 O 3–δ (BCFN) and BaCO 3 , to enhance the ORR activity and durability of the state-of-the-art lanthanum strontium cobalt ferrite (La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3–δ , LSCF) cathode is reported. The conformal MP catalyst-coated LSCF cathode shows a polarization resistance (R p ) of 0.048 Ω cm 2 at 650 °C, about one order of magnitude smaller than that of the bare LSCF. In an accelerated Cr-poisoning test, the degradation rate of the catalyst-coated LSCF electrode is 10 –3 Ω cm 2 h –1 (0.59% h –1 ) over 200 h, only one fifth of the degradation rate of the bare LSCF electrode at 750 °C. In addition, anode-supported single cells with the MP catalyst-coated LSCF cathode show a dramatically enhanced peak power density (1.4 W cm –2 vs 0.67 W cm –2 at 750 °C) and increased durability against Cr and H 2 O. Both experimental results and density functional theory-based calculations indicate that the BCFN phase improves the ORR activity while the BaCO 3 phase enhances the stability of the LSCF cathode.
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Biomass is a promising renewable feedstock for conversion to high performance sustainable aviation fuel (SAF) to mitigate greenhouse gas emissions in air travel.
A model of a fuel-cell cathode with distinct proton conductivities at the agglomerate and electrode scales was used to simulate polarization curves under conditions with facile oxygen transport. Here, the model was applied to electrodes containing agglomerates with different ratios of platinum to carbon in order to examine the hypothesis that intra-agglomerate proton conductivity is substantially lower than ionomer conductivity. The model predicts decreasing performance and increasing sensitivity to Pt/C ratio as intra-agglomerate conductivity declines relative to a constant through-electrode conductivity. Experiments on catalyst layers with Vulcan supports do not show the predicted trend indicating that mesoscale intra-agglomerate conductivity is not orders of magnitude lower than bulk ionomer conductivity.
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