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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Optimal Substrate Preheating Model for Thermal Spray Deposition of Thermosets onto Polymer Matrix Composites

High velocity oxy-fuel (HVOF) sprayed, functionally graded polyimide/WC-Co composite coatings on polymer matrix composites (PMC's) are being investigated for applications in turbine engine technologies. This requires that the polyimide, used as the matrix material, be fully crosslinked during deposition in order to maximize its engineering properties. The rapid heating and cooling nature of the HVOF spray process and the high heat flux through the coating into the substrate typically do not allow sufficient time at temperature for curing of the thermoset. It was hypothesized that external substrate preheating might enhance the deposition behavior and curing reaction during the thermal spraying of polyimide thermosets. A simple analytical process model for the deposition of thermosetting polyimide onto polymer matrix composites by HVOF thermal spray technology has been developed. The model incorporates various heat transfer mechanisms and enables surface temperature profiles of the coating to be simulated, primarily as a function of substrate preheating temperature. Four cases were modeled: (i) no substrate preheating; (ii) substrates electrically preheated from the rear; (iii) substrates preheated by hot air from the front face; and (iv) substrates electrically preheated from the rear and by hot air from the front.

Ivosevic, M.↗
NASA NTRS2007

NIRSS Upgrades: Final Report

This year we were able to further the NIRSS program by re-writing the data ingest and display code from LabVIEW to C++ and Java. This was leveraged by a University of Colorado Computer Science Department Senior Project. The upgrade made the display more portable and upgradeable. Comparisons with research aircraft flights conducted during AIRS-2 were also done and demonstrate reasonable skill in determining cloud altitudes and liquid water distribution. Improvements can still be made to the cloud and liquid logic. The icing hazard index was not evaluated here since that represents work in progress and needs to be made compatible with the new CIP-Severity algorithm. CIP is the Current Icing Potential product that uses a combination decision tree/fuzzy logic algorithm to combine numerical weather model output with operational sensor data (NEXRAD, GOES, METARs and voice pilot reports) to produce an hourly icing diagnosis across the CONUS. The new severity algorithm seeks to diagnose liquid water production through rising, cooling air, and depletion by ice processes. The information used by CIP is very different from that ingested by NIRSS but some common ground does exist. Additionally, the role of NIRSS and the information it both needs and provides needs to be determined in context of the Next Generation Air Traffic System (NGATS). The Weather Integrated Products Team has a plan for an Initial Operating Capability (IOC) to take place in 2012. NIRSS is not explicitly a part of that IOC but should be considered as a follow-on as part of the development path to a 2025 full capability.

Politovich, Marcia K.↗
NASA NTRS2010

In-Line Capacitance Sensor for Real-Time Water Absorption Measurements

A capacitance/dielectric sensor was designed, constructed, and used to measure in real time the in-situ water concentration in a desiccant water bed. Measurements were carried out with two experimental setups: (1) passing nitrogen through a humidity generator and allowing the gas stream to become saturated at a measured temperature and pressure, and (2) injecting water via a syringe pump into a nitrogen stream. Both water vapor generating devices were attached to a downstream vertically-mounted water capture bed filled with 19.5 g of Moisture Gone desiccant. The sensor consisted of two electrodes: (1) a 1/8" dia stainless steel rod placed in the middle of the bed and (2) the outer shell of the stainless steel bed concentric with the rod. All phases of the water capture process (background, heating, absorption, desorption, and cooling) were monitored with capacitance. The measured capacitance was found to vary linearly with the water content in the bed at frequencies above 100 kHz indicating dipolar motion dominated the signal; below this frequency, ionic motion caused nonlinearities in the water concentration/capacitance relationship. The desiccant exhibited a dielectric relaxation whose activation energy was lowered upon addition of water indicating either a less hindered rotational motion or crystal reorientation.

Nurge, Mark A.↗
NASA NTRSDate not supplied

Effect of Heat Treatment on the Microstructure and Mechanical Properties of Monel K500 Alloy Fabricated Via L-PBF and LP-DED

This study examines and compares the effect of different heat treatments (HT) on the microstructure and mechanical properties of Monel K500 fabricated using laser powder bed fusion (L-PBF) and laser powder directed energy deposition (LP-DED) technologies. The as-fabricated Monel K500 specimens exhibited dendritic microstructure and elemental micro-segregation due to high cooling rates induced during the fabrication process. The applicability of HT proposed in the literature for wrought Monel K500 was investigated for L-PBF and LP-DED using four different HT procedures involving hot isostatic pressing (HIP), solution annealing (SA), and aging. The mechanical properties of test specimens were evaluated using uniaxial tensile testing at room temperature. The microstructural evolution of test specimens during HT was analyzed using a scanning electron microscope. For all HT conditions investigated, L-PBF Monel K500 specimens consistently displayed higher strength and lower ductility compared to the LP-DED counterparts. The HT procedure involving HIP at 1160°C for 3hr at 100 MPa, SA at 1100°C for 15 min, and three step aging at 610°C for 16 hr, 540°C for 6 hr, and 480°C for 8 hr resulted in highest strength for both L-PBF and LP-DED fabricated Monel K500.

Additive manufacturing↗
DOE OSTI2022

CODE-TO-CODE BENCHMARK STUDY FOR THERMAL STRESS MODELING AND PRELIMINARY ANALYSIS OF THE HIGH-TEMPERATURE SINGLE HEAT PIPE EXPERIMENT

Microreactors are very small nuclear reactors with typical thermal-energy output of up to 20 MWth. The microreactor concept is gaining more and more attention for safe, robust, and reliable supply of electricity for remote locations and to meet industrial process heat needs. Heat-pipe-cooled microreactor is one of the microreactors being investigated at Idaho National Laboratory. In the heat-pipe-cooled microreactor, heat pipes remove heat from the reactor core as a passive heat-transfer device, so the fluid circulation is not required for cooling, which can substantially simplify the overall reactor design. However, given the extremely high temperatures in the core region and potentially large temperature gradients across the structure materials, thermal stresses need to be well-analyzed to ensure structural integrity during normal operations and accident scenarios for the heat-pipe-cooled microreactor designs. This paper discusses finite element method-based thermal-stress analysis for the high-temperature single heat-pipe test article in the Single Primary Heat Extraction and Removal Emulator (SPHERE) facility at Idaho National Laboratory, using two commercial software packages, Abaqus and STAR-CCM+. A code-to-code benchmark study was performed to crosscheck the model setup and capability of each code and to gain insights into the potential thermal stress concerns from the current experimental setup. It is observed the significant thermal stresses happen at the locations where the largest temperature gradients appeared between heat pipe and electric heater. The temperature fields have good agreements between Abaqus and STAR-CCM+, while the induced thermal stresses show modest deviations probably due to differences of meshing engines used in these two codes.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2022

Experimental Investigation of the Effect of Atomizing Electrospray Nozzles on the Cooling and Reduced Humidification of Air

Separating sensible and latent cooling have shown the potential to reduce energy consumption in A/C systems for building HVAC applications. Several technologies exist based on vapor-compression refrigeration, enthalpy wheels, chemical adsorption and absorption materials, and mechanical cooling. However, their thermodynamics limits and high energy consumption hinder their deployment in hot and humid climatic regions. This paper focuses on separating sensible and latent cooling by using a new thermodynamics process and in-kind (i.e., non-vapor compression-based) technology. Highly electrically charged water droplets were sprayed in the airflow. These droplets attracted water vapor molecules to their surfaces and promoted condensation. The phenomenon was the result of simultaneous dielectrophoresis and electro-diffusion interactions. Studies in the literature have shown that using multiple capillary electrodes reduced air moisture by up to 5% when using nanometer-size droplets in the spray. Unfortunately, these studies were limited to low airflow rates, and the objective of this paper was to investigate how to scale up this in-kind approach to airflows typical of buildings. In the present paper, droplets of micrometer size were utilized to control the humidity for a 5-cfm flow rate. While this airflow was still low for building applications, it was 100 times fold the airflows in the literature studies. The air was tested at 20°C and at 50 and 80% relative humidity. A two-fluid atomizing nozzle produced the droplets in the spray, and high DC electric potential, up to 25 kV, was used to charge the fine droplets electrically. The air atomizing nozzle with high voltage potential resembled an evaporative cooler process. However, a measurable reduction of the absolute humidity of up to 2% was observed compared to the case of the nozzle with no high voltage potential. The entire device had one small nozzle selected from off-the-shelf components and had less than a 9 cm2 footprint area.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

Mobile Sorption-based Thermal Battery for Harvesting Low-Temperature Geothermal Energy

Around 20% of the total primary energy in the United States is consumed for thermal demands of buildings such as space cooling, dehumidification, and space heating (EIA 2018). Low-temperature geothermal energy is abundant and can effectively satisfy buildings’ thermal demands. However, low-temperature geothermal energy is underutilized because the energy density of geothermal fluid is too low to justify the costs associated with transporting it between existing geothermal resources and buildings. The mobile sorption-based thermal battery (MSTB) system has been developed using three-phase (i.e., vapor–liquid, solution–solid, crystal) sorption technology to harvest low-temperature heat and store it with a much higher energy density than the geothermal fluid. The energy density of salt crystals is over six times higher than geothermal fluid, which makes long-distance transportation of salt crystals economically feasible. Salt crystals can be used to dehumidify air or provide space cooling in buildings, which alleviates peak demand on the electricity grid by offsetting electricity use for these end uses. This helps improve the grid’s stability and resilience. High-energy storage density, fast crystallization, and dissolution of salt crystals are all critical to the viability and performance of the MSTB system. Therefore, the design and operation of MSTB systems need to ensure effective generation and dissolution of salt crystals inside the MSTB. To achieve this target, this seedling project developed an experimental apparatus for characterizing the crystallization and dissolution processes. The energy density and potential latent cooling capacity of the MSTB are also evaluated based on lab test results. The crystallization results showed that the generated lithium chloride hydrate crystals are fluffy, the crystallization process lasts about 50 min, and the maximum crystal fraction (i.e., the ratio of crystal mass to the mass in the MSTB) can be up to 51.1% of the total mass in the MSTB at a solution flow rate of 1.58 g/s. The dissolution results show that the salt crystals in the MSTB can be fully dissolved within 15–28 min, based on different test conditions. Reducing solution flow rate and cooling water temperature can achieve increased energy storage density and crystal fraction. While the increase in the discharge rate (i.e., latent cooling capacity for dehumidifying air) is achieved by increasing flow rate and temperature of inlet diluted solution, as well as by using a pump for internal solution circulation, the discharge rate increases by 38%, from 0.95 kW to 1.31 kW. Compared with increasing the inlet solution flow rate, power consumption of salt solution transportation can be reduced by using a pump for internal solution circulation. The crystallization test results also showed that the maximum energy storage density is 981.8 kJ/kg, and the maximum discharge rate of the dissolution tests is ≤1.79 kW. Both are above the target values of 900 kJ/kg and 1.75 kW) for this project. The work reported here proves the feasibility and advancement of the MSTB system, which is helpful to the further study and improvement of the MSTB system.

15 GEOTHERMAL ENERGY↗
NASA NTRS1992

Vibrational relaxation of anharmonic oscillators in expanding flows

Although the Landau-Teller vibrational model accurately predicts vibrational excitation process in post-shock and compressing flows, it under-predicts the rate of de-excitation in cooling and expanding flows. In the present paper, detailed calculations of the vibrational relaxation process of N2 and CO in cooling flows are conducted. A coupled set of vibrational transition rate equations and quasi-one-dimensional fluid dynamic equations is solved. Multiple quantum level transition rates are computed using SSH theory. The SSH transition rate results are compared with available experimental data and other theoretical models. Vibration-vibration exchange collisions are responsible for some vibrational relaxation acceleration in situations of high vibrational temperature and low translational temperature. The present results support the relaxation mechanisms proposed by Bray and by Treanor Rich and Rehm.

Ruffin, Stephen M.↗
NASA NTRS1988

Acoustic levitation technique for containerless processing at high temperatures in space

High temperature processing of a small specimen without a container has been demonstrated in a set of experiments using an acoustic levitation furnace in the microgravity of space. This processing technique includes the positioning, heating, melting, cooling, and solidification of a material supported without physical contact with container or other surface. The specimen is supported in a potential energy well, created by an acoustic field, which is sufficiently strong to position the specimen in the microgravity environment of space. This containerless processing apparatus has been successfully tested on the Space Shuttle during the STS-61A mission. In that experiment, three samples wer successfully levitated and processed at temperatures from 600 to 1500 C. Experiment data and results are presented.

Rey, Charles A.↗
DOE OSTI2024

ILAW Container Cost Reduction and Optimization Study

This study, performed on behalf of Washington River Protection Solutions (WRPS), examines the potential for making cost savings for the Immobilized Low Active Waste (ILAW) containers over the mission life of the Waste Treatment and Immobilization Plant (WTP). it builds on earlier study assessments 24590-LAW-RPT-M-01-001 Rev 0 ILAW Product Container Specifications Optimization Study and DOE/ORP-2013-02 Rev 0 Decision Analysis of Low-Active Waste Container Finishing Handling System Alternatives. The WTP design and installed equipment has evolved over an extended period ~20 years. Consequently, some of the existing requirements relating the ILAW containers may no longer be applicable under current mission plans where the glass filled containers are placed into the Integrated Disposal Facility (IDF) rather than stacked in an engineered purpose-built ventilated store as originally envisioned. The study team reviewed available WTP project reference documents to establish the functions the container must perform and assign requirements against each of these functions. With the assumptions that some of the existing WTP contract restrictions would not necessarily apply to the subsequent facility operations contract the container requirements were reviewed to identify those which were ‘hard constraints‘, imposed by regulatory requirements. Initially each of these hard constraints were reviewed, evaluated and documented to see if they precluded the use of an alternate less expensive material of construction, carbon steel, to the existing 304 L stainless steel in the current container specification. That review did not generate any fatal flaws for a change in material of construction to carbon steel allowing the study team to examine the impacts of material cost savings, potential changes to the design and requirements and impacts on interfaces of the containers with the existing WTP process equipment from container receipt, transfers, glass filling, cooling and export. In addition, a change in container target fill level was evaluated and qualitative, and quantitative where feasible, impacts to the container fabrication process assessed. Lastly, additional follow on development or testing activities to support the use of carbon steel were assessed and a recommended path forward with a ROM cost and timescale developed.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS2015

Failure Analysis Results and Corrective Actions Implemented for the EMU 3011 Water in the Helmet Mishap

During EVA (Extravehicular Activity) No. 23 aboard the ISS (International Space Station) on 07/16/2013 water entered the EMU (Extravehicular Mobility Unit) helmet resulting in the termination of the EVA (Extravehicular Activity) approximately 1-hour after it began. It was estimated that 1.5-L of water had migrated up the ventilation loop into the helmet, adversely impacting the astronauts hearing, vision and verbal communication. Subsequent on-board testing and ground-based TT and E (Test, Tear-down and Evaluation) of the affected EMU hardware components led to the determination that the proximate cause of the mishap was blockage of all water separator drum holes with a mixture of silica and silicates. The blockages caused a failure of the water separator function which resulted in EMU cooling water spilling into the ventilation loop, around the circulating fan, and ultimately pushing into the helmet. The root cause of the failure was determined to be ground-processing short-comings of the ALCLR (Airlock Cooling Loop Recovery) Ion Filter Beds which led to various levels of contaminants being introduced into the Filters before they left the ground. Those contaminants were thereafter introduced into the EMU hardware on-orbit during ALCLR scrubbing operations. This paper summarizes the failure analysis results along with identified process, hardware and operational corrective actions that were implemented as a result of findings from this investigation.

Steele, John↗
DOE OSTI2022

Design optimization of integrated cooling inserts in modular Fischer-Tropsch reactors

Sustainable production of liquid fuels and feedstocks from atmospheric CO 2 through carbon recycling technologies is necessary to broaden decarbonization efforts and further reduce global emissions. Fischer–Tropsch (FT) reactors can address this challenge by providing storable, high-value liquid hydrocarbon fuels and feedstocks from syngas generated through reductive CO 2 utilization. FT technology, however, is most cost effective at large-scale, fixed-site plants and does not effectively address the smaller, globally distributed CO 2 point sources. Alternatively, smaller, modular reactors can be composed together to the specific scale of the emission source, yielding a flexible solution that enables more widespread deployment. In these modular reactors, thermal management using a finned cooling insert embedded within the catalyst matrix is critical to maintaining the performance and viability. Thus, in this work, topology optimization is used to determine the cooling insert geometry that maximizes reactor productivity while preventing auto-thermal runaway. Optimal designs are generated for varying number of constituent fins and over a range of maximum operating temperatures. Constraints including minimum feature length-scales and prescribed cooling insert material are imposed on the designs to enhance manufacturability. The impact of design features such as insert tapering and increased length scale hierarchy is automatically revealed by the systematic design framework employed. Here, this approach thus generates novel optimal geometries while automating, accelerating, and enhancing the design process compared to traditional heuristic approaches for cooling insert design in modular FT reactors.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2024

Field Validation of Electrochemical Water Filtration System on an Open Loop Cooling Tower at Nissan Manufacturing Plant in Canton, Mississippi

The U.S. Department of Energy Industrial Efficiency and Decarbonization Office’s Industrial Technology Validation (ITV) program aims to identify and demonstrate the performance of new, emerging, and underutilized technologies in the industrial sector to help inform decisions towards accelerating commercialization and deployment. This ITV demonstration investigated the performance of an early-commercial electrochemical water treatment technology on a cooling tower at an automotive plant. Cooling towers are vital equipment for dissipating heat from industrial processes, but they face challenges related to scaling, corrosion, and the growth of biological contaminants. Effective cooling tower water treatment is therefore essential in reducing these contaminants and other total suspended solids (TSS) and total dissolved solids (TDS). Various treatment systems, such as sand-based filters, centrifugal separators, and disc filters are available, each having its advantages and drawbacks. ElectroCell Systems, a filtration technology provider, offers an electrochemistry-based water treatment system that is skid-mounted and can be configured as a side-stream filtration system.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

Comparison of plug flow and multi-node stratified tank modeling approaches regarding computational efficiency and accuracy

Residential water heaters contain water stratified by temperature-driven density differences. This implies that a water tank can reach a state in which the top and bottom sections have different temperatures, unless mixing happens. A high degree of thermal stratification can improve the efficiency of some water heaters, by saving the amount of energy required for the heat-up process. Studies of stratification became popular in the 1970s and it remains an active research topic today. The research has led to the development of different models and techniques to better predict and define a stratified tanks behavior. By comparing these models and techniques used previously to describe thermal stratification, the phenomenon could be better understood, exploited, and used to increase efficiency and thermal energy capacity in modern water tanks. From the existing models, we found the one-dimensional standard plug-flow and a multi node model to be appropriate for analyzing the processes of the heat up and cool-down in a water tank. These two models are based on energy balances. This work involved comparing the accuracy and computational effort needed to implement these models. To assess accuracy, we compared both types of existing models to experimental data (also collected in this work) which included a heat up process using an external heat pump. This external process included a layering process that has an eddy diffusivity at five times the rate of thermal diffusion. For this project, we implemented the models in MATLAB, the multi-paradigm numerical computing environment. We quantified model accuracy using the root mean squared error between modeled data and experimental data for six measured tank temperatures. Comparing the accuracy and the computational time taken to run the simulation provides a method to contrast the performance of each model and a way to rate it. The multi node model was run using from 6 to 96 spatial nodes; the plug flow model was run using 1 to 0.001 º C temperature bin sizes. Additionally, timesteps were varied from 4 to 236 s. The results quantify the tradeoff between accuracy and computational time, providing guidance for simulations to intelligently select the best model type and simulation parameters. This research can be used to validate the pre-existing models and possibly improve the modern water tank.

Bulnes, Fernando Karg↗
NASA NTRS1999

Interaction Between Tropical Convection and its Embedding Environment: An Energetics Analysis of a 2-D Cloud Resolving Simulation

The phase relation between the perturbation kinetic energy (K') associated with the tropical convection and the horizontal-mean moist available potential energy (bar-P) associated with environmental conditions is investigated by an energetics analysis of a numerical experiment. This experiment is performed using a 2-D cloud resolving model forced by the TOGA-COARE derived vertical velocity. The imposed upward motion leads to a decrease of bar-P directly through the associated vertical advective cooling, and to an increase of K' directly through cloud related processes, feeding the convection. The maximum K' and its maximum growth rate lags and leads, respectively, the maximum imposed large-scale upward motion by about 1-2 hours, indicating that convection is phase locked with large-scale forcing. The dominant life cycle of the simulated convection is about 9 hours, whereas the time scales of the imposed large-scale forcing are longer than the diurnal cycle. In the convective events, maximum growth of K' leads maximum decay of the perturbation moist available potential energy (P') by about 3 hours through vertical heat transport by perturbation circulation, and perturbation cloud heating. Maximum decay of P' leads maximum decay of bar-P by about one hour through the perturbation radiative, processes, the horizontal-mean cloud heating, and the large-scale vertical advective cooling. Therefore, maximum gain of K' occurs about 4-5 hours before maximum decay of bar-P.

Li, Xiaofan↗
NASA NTRS2003

Evaporation Loss of Light Elements as a Function of Cooling Rate: Logarithmic Law

Knowledge about the evaporation loss of light elements is important to our understanding of chondrule formation processes. The evaporative loss of light elements (such as B and Li) as a function of cooling rate is of special interest because recent investigations of the distribution of Li, Be and B in meteoritic chondrules have revealed that Li varies by 25 times, and B and Be varies by about 10 times. Therefore, if we can extrapolate and interpolate with confidence the evaporation loss of B and Li (and other light elements such as K, Na) at a wide range of cooling rates of interest based upon limited experimental data, we would be able to assess the full range of scenarios relating to chondrule formation processes. Here, we propose that evaporation loss of light elements as a function of cooling rate should obey the logarithmic law.

Xiong, Yong-Liang↗
DOE OSTI2020

Performance of Public Film Cooling Geometries Produced Through Additive Manufacturing

Abstract Film cooling is an essential cooling technology to allow modern gas turbines to operate at high temperatures. For years, researchers in this community have worked to improve the effectiveness of film cooling configurations by maximizing the coolant coverage and minimizing the heat flux from the hot gas into the part. Working toward this goal has generated many promising film cooling concepts with unique shapes and configurations. However, until recently, many of these designs were challenging to manufacture in actual turbine hardware due to limitations with legacy manufacturing methods. Now, with the advances in additive manufacturing, it is possible to create turbine parts using high-temperature nickel alloys that feature detailed and unique geometry features. Armed with this new manufacturing power, this study aims to build and test the promising designs from the public literature that were previously difficult or impossible to implement. In this study, different cooling hole designs were manufactured in test coupons using a laser powder bed fusion process. Each nickel alloy coupon featured a single row of engine scale cooling holes, fed by a microchannel. To evaluate performance, the overall cooling effectiveness of each coupon was measured using a matched Biot test at engine relevant conditions. The results showed that certain hole shapes are better suited for additive manufacturing than others and that the manufacturing process can cause significant deviations from the performance reported in the literature.

Engineering↗