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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Mass transfer intensification through increased surface wetting and liquid turbulence using 3D printing structured packing for CO2 capture

The absorber column is one of the most expensive pieces of equipment to construct in the solvent-based post-combustion carbon capture unit. In order to decrease the absorber size and reduce capital costs, novel polymer packings were proposed by enhancing surface wettability and local turbulence within liquid solvent. The novel packings intensify the mass transfer in CO2 absorption and show better separation efficiency than traditional structured packings. In this work, the economic influence of applying the more efficient packing with a shorter absorber column is studied in a techno-economic analysis for a carbon capture unit at a coal-fired power plant. The baseline case includes CO2 capture unit in a supercritical pulverized coal power plant to generate 650 MWe (net) of electricity, where the additional CO2 capture unit leads to 63.4% increase of LCOE. While implementing UK PCC with traditional and novel packings, there will be 47.2% and 46.4% LCOE increase separately, both of which are lower than the baseline value. Applying more efficient packing and smaller absorber could further lessen the LCOE increase. The UK PCC with traditional packings reduces CO2 capture cost by 23.4% and the application of the advanced packings allows to the reduction increases to 24.4%.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Parallelized domain decomposition for multi-dimensional Lagrangian random walk mass-transfer particle tracking schemes

Lagrangian particle tracking schemes allow a wide range of flow and transport processes to be simulated accurately, but a major challenge is numerically implementing the inter-particle interactions in an efficient manner. This article develops a multi-dimensional, parallelized domain decomposition (DDC) strategy for mass-transfer particle tracking (MTPT) methods in which particles exchange mass dynamically. We show that this can be efficiently parallelized by employing large numbers of CPU cores to accelerate run times. In order to validate the approach and our theoretical predictions we focus our efforts on a well-known benchmark problem with pure diffusion, where analytical solutions in any number of dimensions are well established. In this work, we investigate different procedures for “tiling” the domain in two and three dimensions (2-D and 3-D), as this type of formal DDC construction is currently limited to 1-D. An optimal tiling is prescribed based on physical problem parameters and the number of available CPU cores, as each tiling provides distinct results in both accuracy and run time. We further extend the most efficient technique to 3-D for comparison, leading to an analytical discussion of the effect of dimensionality on strategies for implementing DDC schemes. Increasing computational resources (cores) within the DDC method produces a trade-off between inter-node communication and on-node work. For an optimally subdivided diffusion problem, the 2-D parallelized algorithm achieves nearly perfect linear speedup in comparison with the serial run-up to around 2700 cores, reducing a 5 h simulation to 8 s, while the 3-D algorithm maintains appreciable speedup up to 1700 cores.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

Advances and perspectives on mass transfer and enzymatic hydrolysis in the enzyme-mediated lignocellulosic biorefinery: A review

We report enzymatic hydrolysis is a critical process for the cellulase-mediated lignocellulosic biorefinery to produce sugar syrups that can be converted into a whole range of biofuels and biochemicals. Such a process operating at high-solid loadings (i.e., scarcely any free water or roughly ≥ 15% solids, w/w) is considered more economically feasible, as it can generate a high sugar concentration at low operation and capital costs. However, this approach remains restricted and incurs “high-solid effects”, ultimately causing the lower hydrolysis yields with increasing solid loadings. The lack of available water leads to a highly viscous system with impaired mixing that exhibits strong transfer resistance and reaction limitation imposed on enzyme action. Evidently, high-solid enzymatic hydrolysis involves multi-scale mass transfer and multi-phase enzyme reaction, and thus requires a synergistic perspective of transfer and biotransformation to assess the interactions among water, biomass components, and cellulase enzymes. Porous particle characteristics of biomass and its interface properties determine the water form and distribution state surrounding the particles, which are summarized in this review aiming to identify the water-driven multi-scale/multi-phase bioprocesses. Further aided by the cognition of rheological behavior of biomass slurry, solute transfer theories, and enzyme kinetics, the coupling effects of flow-transfer-reaction are revealed under high-solid conditions. Based on the above basic features, this review lucidly explains the causes of high-solid hydrolysis hindrances, highlights the mismatched issues between transfer and reaction, and more importantly, presents the advanced strategies for transfer and reaction enhancements from the viewpoint of process optimization, reactor design, as well as enzyme/auxiliary additive customization.

45 multi-scale, multi-phase, enzymatic reaction↗
DOE OSTI2025

On the validity and limitations of 1D model for heat and mass transfer performance evaluation in a multilayer binder-free desiccant dehumidifier: isothermal dehumidification with internal cooling

Efficient humidity control is essential for maintaining indoor thermal comfort, yet conventional vapor-compression-based dehumidifiers are energy-intensive. Employing separate sensible and latent cooling through desiccant-coated heat exchangers (DCHEs) combined with evaporative coolers offers energy savings of up to 80 % compared to conventional systems. However, the dehumidification performance of DCHEs remains limited due to the use of polymer binders for coating desiccant materials onto heat exchange surfaces. In our previous study, we developed a multilayer fixed-bed binder-free desiccant dehumidifier (MFBDD) that demonstrated high dehumidification capacity and low pressure drop compared to rotary desiccant wheels. Nevertheless, its potential for further enhancement through internal cooling and the use of step-shaped adsorption isotherms has not been explored. In this study, a physics-based one-dimensional (1D) transient model is developed and validated to capture the coupled heat and mass transfer processes in the MFBDD and extended to simulate internal cooling using a high-capacity composite metal–organic framework, MIL-101/GO-6 (water uptake ≈1.6 g/g within 35–47 % RH). The model enables detailed analysis of local air and bed temperature dynamics and quantifies how internal cooling affects the dehumidification performance under a wide range of operating conditions. Results show that integrating internal cooling and using MIL-101/GO-6 enhance mass adsorbed, moisture removal capacity, and dehumidification effectiveness by 50 %–99 % compared with the M.S. Gel baseline. The study further reveals that achieving near-isothermal operation requires simultaneous enhancement of the convective heat transfer coefficient and heat exchange surface area. In conclusion, this work provides the first detailed physical insight into the interplay between internal cooling and step-shaped isotherms in a binder-free desiccant device and establishes a validated modeling framework for scaling up and system-level performance evaluation of next-generation energy-efficient dehumidification systems.

Heat and mass transfer↗
DOE OSTI2025

Visualizing the mass transfer flow in direct-impact accretion

We use a variety of visualization techniques to display the interior and surface flows in a double white dwarf binary undergoing direct-impact mass transfer and evolving dynamically to a merger. The structure of the flow can be interpreted in terms of standard dynamical, cyclostrophic, and geostrophic arguments. We describe and showcase some visualization and analysis techniques of potential interest for astrophysical hydrodynamics. In the context of R Coronae Borealis stars, we find that mixing of accretor material with donor material at the shear layer between the fast accretion belt and the slower rotating accretor body will always result in some dredge-up. We also discuss briefly some potential applications to other types of binaries.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Impacts of Biomass Feedstock Pre-Processing on Heat and Mass Transfer During Pyrolysis Using X-Ray Computed Tomography and Multiscale Modeling

Knowledge of the transport properties of biomass particles such as porosity, tortuosity, and permeability is paramount for high-fidelity modeling of biomass pyrolysis due to the heat and mass transfer limitations imposed by particle microstructure. X-ray computed tomography (XCT) is a non-destructive imaging method that enables full 3D reconstructions of the biomass particle microstructure with high resolution, permitting direct calculation of porosity, tortuosity, and permeability from real particle geometries. In this study, XCT imaging revealed the 3D microstructures of particles and chars from pyrolytic conversion of cylindrically cut or milled/pelletized loblolly pine samples. The porosity, tortuosity, and permeability were calculated directly from the XCT geometries via open-source microstructural analysis tool MATBOX+TauFactor (https://github.com/NREL/MATBOX_Microstructure_analysis_toolbox) and computational fluid dynamics (CFD) simulations using our solver, Mesoflow (https://github.com/NREL/mesoflow). These properties were used in a reactor scale model developed in COMSOL of the single particle reactor at NREL to investigate the impact of feedstock pre-processing on biomass conversion during pyrolysis with rigorous experimental validation.

biomass↗
DOE OSTI2022

Continuum Model to Define the Chemistry and Mass Transfer in a Bicarbonate Electrolyzer

Bicarbonate electrolyzers are devices designed to convert CO 2 captured from point sources or the atmosphere into chemicals and fuels without needing to first isolate pure CO 2 gas. In this work, we report here an experimentally validated model that quantifies the reaction chemistry and mass transfer processes within the catalyst layer and cation exchange membrane layer of a bicarbonate electrolyzer. Our results demonstrate that two distinct chemical microenvironments are key to forming CO at high rates: an acidic membrane layer that promotes in situ CO 2 formation and a basic catalyst layer that suppresses the hydrogen evolution reaction. We show that the rate of CO product formation can be increased by modulating the catalyst and membrane layer properties to increase the rate of in situ CO 2 generation and transport to the cathode. These insights serve to inform the design of bicarbonate and BPM-based CO 2 electrolyzers while demonstrating the value of modeling for resolving rate-determining processes in electrochemical systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Heat and mass transfer during a sudden loss of vacuum in a liquid helium cooled tube - Part III: Heat deposition in He II

A sudden loss of vacuum can be catastrophic for superconducting particle accelerators. In such an event, air leaks into the liquid-helium-cooled accelerator beamline tube and condenses on its inner surface, causing rapid boiling of the helium and dangerous pressure build-up. Understanding the coupled heat and mass transfer processes is important for the design of the beamline cryogenic system. Our past experimental study on nitrogen gas propagating in a copper tube cooled by normal liquid helium (He I) has revealed a nearly exponential slowing down of the gas front. A theoretical model that accounts for the interplay of the gas dynamics and the condensation was developed, which successfully reproduced various key observations. However, since many accelerator beamlines are actually cooled by superfluid helium (He II) in which the heat transfer is via a non-classical thermal counterflow mode, we need to extend our work to the He II cooled tube. This paper reports our systematic measurements using He II and the numerical simulations based on a modified model that accounts for the He II heat-transfer characteristics. By tuning the He II peak heat-flux parameter in our model, we have reproduced the observed gas dynamics in all experimental runs. The fine-tuned model is then utilized to reliably evaluate the heat deposition in He II. Finallly, this work not only advances our understanding of condensing gas dynamics but also has practical implications to the design codes for beamline safety.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Fluid-Driven Mass Transfer During Retrograde Metamorphism and Exhumation of the UHP Western Gneiss Region Terrane, Norway

Dehydration reactions within subducted oceanic crust are important for fluid-mediated element transfer within the subducting plate and potentially to the mantle wedge. The effects of metamorphic reactions and fluid flow on element recycling that occur during retrogression and exhumation of subducted continental crust from mantle depths are poorly understood. We study two metabasite pods with fresh eclogite cores and retrogressed amphibolite-facies rims and surrounding host gneiss within the Western Gneiss Region (WGR), Norway, to better understand element mobility and mass transfer during exhumation of subducted continental crust. Bulk-rock data were collected from samples taken across the pod and into the host gneiss. Phengite breakdown in eclogite and epidote recrystallization in veins and/or gneiss within pod cores contributed large ion lithophile elements and REE to retrogressed eclogite closest to the pod cores. In gneiss hosting the pods, phengite and epidote breakdown provided fluid that mediated elemental transfer and redistribution to the pod rim or tail. Compared to the studied pod in the southern WGR, the pod in the northern WGR underwent higher P-T conditions, partial melting and higher strain rates. This resulted in the infiltration of external fluid farther into the pod interior from the rim and facilitated larger mass gain in trace elements in the amphibolite tail of the pod relative to fresh eclogite in the core. The results show clear evidence for retrogression dehydration reactions driving significant fluid-mediated element redistribution as observed on the outcrop scale during exhumation following ultrahigh-pressure metamorphism, which directly impacts element signatures within the exhuming crust.

58 GEOSCIENCES↗
DOE OSTI2020

Aluminum-doped calcium manganite particles for solar thermochemical energy storage: Reactor design, particle characterization, and heat and mass transfer modeling

A two-step cycle is discussed for solar thermochemical energy storage based on particulate aluminum-doped calcium manganite reduction/oxidation reactions for direct integration into Air Brayton cycles. The two steps encompass 1) the storage of concentrated solar irradiation within endothermic reduction of aluminum-doped calcium manganite and 2) the delivery of heat to an Air-Brayton cycle via exothermic re-oxidation of oxygen-deficient aluminum-doped calcium magnanite. A 5 kW th scale solar thermochemical reactor operating under vacuum was designed, modeled, and optimized to thermally reduce a continuous, gravity-driven flow of aluminum-doped calcium manganite particles. The granular flows were characterized in a tilt-flow rig, and particle image velocimetry was used to determine flow properties via frictional and velocity scaling relationships. Flow properties were integrated into a detailed heat and mass transfer model of the solar thermochemical reactor. A reactor design with 31° inclination angle, 230 g/min of particles, and 5.2 kW th radiative input from the high-flux solar simulator was discovered to produce an outlet flow temperature of 1158 K, with stoichiometric deviations of 0.076 and a storage efficiency of 0.628 while avoiding particle overheating and promoting longer particle residence times.

14 SOLAR ENERGY↗
DOE OSTI2022

Heat and mass transfer in hygroscopic hydrogels

Sorption and desorption with hygroscopic hydrogels hold significant promise for thermal management, passive cooling, thermal energy storage, and atmospheric water harvesting. However, a comprehensive understanding of the energy and mass transport mechanisms in hygroscopic hydrogels remains missing, impeding accurate modeling and optimization. In this paper, we develop a model for the simultaneous vapor, water, and heat transfer in hygroscopic hydrogels during sorption and desorption processes. We show that by considering vapor diffusion in the hydrogel micropores, water diffusion in the polymer mesh, and heat transfer in the porous hydrogel, we can accurately capture experimentally observed thermally-driven desorption rates in these hydrogels. Furthermore, we consider three typical operating configurations of hydrogels and elucidate the differences in the transport mechanisms depending on the configuration. Finally, for each of these configurations, we identify key design parameters, including hydrogel thickness, hydrogel shear modulus, heat transfer coefficient, and thermal conductivity, and we parametrically show that by varying these parameters, a hygroscopic hydrogel can desorb up to 128.5%, 14.9%, 69.7%, and 9.6% more water, respectively, relative to the initial water content. This work provides a generic framework to model sorption and desorption processes in hygroscopic hydrogels which can guide the design and optimization in applications of thermal management, passive cooling, thermal energy storage, and atmospheric water harvesting with hydrogels.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Nanoionics Drastically Accelerating Mass Transfer at Elevated Temperatures over 750 °C

Nanoionics were previously considered thermally unstable and infeasible for devices operating above 500 °C. Here, we elucidate the design principle for establishing stable nanoionics from various oxides. We utilized reversible solid oxide cells (SOCs) as the test bed and implemented nanoionics using atomic layer deposition (ALD). We demonstrate a straightforward, interface-controlled, practical approach to render a conformal, ∼15 nm thick ALD film, which initially thermodynamically favors the formation of a solid solution with the substrate into surface nanoionics with single or double layers of nanograins with random crystal orientations. The nanoionics exhibited conductivity estimated to be 7 orders of magnitude higher than that of their bulk-scale counterpart. They demonstrated conformability with uniform grain sizes of ∼15 nm, even after electrochemical operation for ∼500 h at 750 °C and 1000 h at 850 °C. The thermal stability and conductivity of such nanoionics represent a conceptual and technological framework in nanoionics.

atomic layer deposition↗
DOE OSTI2025

A heat and mass transfer model for evaluation of damaged cesium chloride radiological sources

Radiological sources are vital to many applications, and typically contain byproducts from waste streams which decay over time to form complex mixtures of elements. Daughter products resulting from these decay processes can introduce complicating factors to the integrity and safety of the vessel that contains the radiological material. Sources containing cesium 137 ( 137 Cs) are of particular interest, because the decay of this isotope produces barium metal which reacts readily and exothermically with oxygen. This work employs physics-based numerical tools to examine the thermal response of a radiological source containing a mixture of cesium and barium in the event that vessel walls are damaged and atmospheric gases contact source material. A parametric study was conducted to determine the sensitivity of the response to various factors, including vessel geometry, source material age, the degree of vessel damage, and other parameters. Here, it was found that the peak temperatures that occurred within the source material strongly depend on these parameters, particularly vessel geometry and age, which determine whether a breach would be a relatively minor accident or a catastrophic incident. Finally, the model’s sensitivity to uncertain thermophysical properties is discussed.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2025

MOSCATO Development and Integration in Fiscal Year 2025: Implementation of Multiphase, Multiphysics Modeling Capabilities for Molten Salt Systems

MOSCATO (Molten Salt Chemistry and Transport) is a multiphysics code that provides high-fidelity, coupled simulations of fluid flow, heat transfer, mass transfer, chemistry, electrochemical phenomena, and alloy corrosion for molten salt systems. In FY25, significant developments were made to the code package, enhancing its capabilities for modeling all relevant phenomena within operating moltens salt reactors (MSRs). The developments and activities in FY25 included: 1. Implementation of Level-Set methods to enable modeling of single-bubble behavior in molten salts. In FY25, the Level-Set two-phase flow modeling implementation was improved to simulate single bubble behavior with molten salt media. The large density and viscosity ratios between typical gases and molten salt liquids present challenges for these types of numerical solvers. With enhancements to the pressure projection method, MOSCATO’s Level-Set solver was able to be successfully validated to experiments related to helium bubble rise in stagnant molten salt. The simulated bubble rising velocity showed reasonable good agreement with experimental measurements. The bubble shape and dynamics were also visually compared with experimental snapshots, demonstrating a good qualitative match. 2. Generation of mass transfer correlations for multiphase flow systems. To enable calculations of the tritium transport across the interface between gas bubbles and salt, we modeled high- Schmidt-number mass transfer around a sphere across a broad range of Reynolds numbers. The mesh near the sphere surface was highly refined to resolve steep concentration gradients caused by the low diffusion coefficient. Literature-based mass transfer correlations were compared with the numerical results, and modifications were proposed to improve agreement, particularly at higher Schmidt numbers. These mass transfer correlations were subsequently provided to other national laboratories to help enable high quality mass transfer simulations using lower-order solvers under development within the NEAMS program. 3. Preliminary implementation of a bubbly flow solver. To model bubbly flow in molten salt, we implemented a bubbly flow solver for void fractions less than 5%. To do so, an algebraic relative velocity model that assumes small bubbles with rapid momentum equilibration was added to MOSCATO to compute bubble velocities. Preliminary comparisons with experimental data showed reasonable agreement, and further improvements are underway. 4. Generation of mass transfer correlations for MSRE subchannel The Molten-Salt Reactor Experiment (MSRE) was a landmark historical project that demonstrated the feasibility of molten-salt reactor technology. The MSRE campaign also generated a significant body of experimental data and reports that continue to support molten-salt–related research. In this report, the MSRE core subchannel was used as the reference geometry for a mass transfer study performed with MOSCATO. The geometry and computational mesh were adapted from a previous study, providing adequate resolution for the relatively low Reynolds number in this case. Additional mesh refinement was applied to reach higher Schmidt numbers, enabling the derivation of a reliable mass-transfer correlation for the present scenario. 5. Simulations of oxygen ingressions into molten salt. In the previous fiscal year, we initiated a study to simulate oxygen ingression in stagnant salt. As oxygen enters the salt through its surface, it reacts with Ce 3+ to form solid CeO 2 and other reaction products. To more fully capture the complex diffusion-convection-reaction mechanisms, capabilities for modeling natural convection in the salt vessel were added. These were needed as the flow of the ingressed gas induced flow in the salt caused by surface shear and non-isothermal effects. With these updated physics in place, we were able to successfully reproduce the experimental results for the rate of change of CeCl 3 concentrations versus time. 6. Flow corrosion model validation. In FY24, MOSCATO’s corrosion model was validated against static corrosion experiments. In FY25, this work was extended to a flow corrosion experiment, where FLiNaK salt was driven by natural convection, with initial salt impurities to initiate corrosion. Despite uncertainties in parameters such as elemental diffusion coefficients in the alloy and unknown H + concentrations, the simulations achieved good agreement with experimental results, especially in predicting sample mass losses.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2022

Heat and Mass Transfer in Hygroscopic Hydrogels

Hygroscopic hydrogels have emerged as a scalable material capable of high-performance vapor sorption for atmospheric water harvesting, dehumidification, and passive cooling due to their fast kinetics and high water uptake. Despite extensive research interest, there is a lack of understanding of the governing energy and mass transport mechanisms within the hydrogels, which hinders their optimization. Here we present a model that explains sorption and desorption in hygroscopic hydrogels for the first time. Our model couples vapor transport in the hydrogel micropores, liquid transport in the polymer nanopores, and heat transport in the porous hydro-gel to accurately capture experimentally observed sorption and desorption data. The knowledge obtained from this model can therefore guide the design of hygroscopic hydrogels and enable improved performance in multi-ple sorption-based applications.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Strategies to overcome mass transfer limitations of hydrogen during anaerobic gaseous fermentations: A comprehensive review

Fermentation of gaseous substrates such as carbon dioxide (CO 2 ) has emerged as a sustainable approach for transforming greenhouse gas emissions into renewable fuels and biochemicals. CO 2 fermentations are catalyzed by hydrogenotrophic methanogens and homoacetogens, these anaerobic microorganisms selectively reduce CO 2 using hydrogen (H 2 ) as electron donor. However, H 2 possesses low solubility in liquid media leading to slow mass transport, limiting the reaction rates of CO 2 reduction. Solving the problems of mass transport of H 2 could boost the advance of technologies for valorizing industrial CO 2 -rich streams, like biogas or syngas. The application could further be extended to combustion flue gases or even atmospheric CO 2 . In this work, an overview of strategies for overcoming H 2 mass transport limitations during methanogenic and acetogenic fermentation of H 2 and CO 2 is presented. Here, the potential for using these strategies in future full-scale facilities and the knowledge gaps for these applications are discussed in detail.

09 BIOMASS FUELS↗