Growth of aerobic and anaerobic bacteria in agar subjected to freezing and diurnal freezing and thawing
Aerobic and anaerobic bacteria growth in agar after freezing and diurnal freezing and thawing
Blank, G. B.↗
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Halo-independent tests of dark matter direct detection signals: local DM density, LHC, and thermal freeze-out
From an assumed signal in a Dark Matter (DM) direct detection experiment a lower bound on the product of the DM-nucleon scattering cross section and the local DM density is derived, which is independent of the local DM velocity distribution. This can be combined with astrophysical determinations of the local DM density. Within a given particle physics model the bound also allows a robust comparison of a direct detection signal with limits from the LHC. Furthermore, the bound can be used to formulate a condition which has to be fulfilled if the particle responsible for the direct detection signal is a thermal relic, regardless of whether it constitutes all DM or only part of it. We illustrate the arguments by adopting a simplified DM model with a Z{sup ′} mediator and assuming a signal in a future xenon direct detection experiment.
43 PARTICLE ACCELERATORS↗
Structural evolution of directionally freeze-cast iron foams during oxidation/reduction cycles
Not Available
Wilke, Stephen K. (ORCID:0000000346747049)↗
Freeze thaw and deicer salt scaling resistance of concrete prepared with alkali aluminosilicate cement
Not Available
Matalkah, Faris↗
Primordial black hole evaporation and dark matter production. II. Interplay with the freeze-in or freeze-out mechanism
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Cellulosic Biomass Sugars to Advantage Jet Fuel: Catalytic Conversion of Corn Stover to Energy Dense, Low Freeze Point Paraffins and Naphthenes (CRADA CRD-12-462 Final Report)
NREL will provide scientific and engineering support to Virent Energy Systems in three technical areas: Process Development/Biomass Deconstruction; Catalyst Fundamentals; and Technoeconomic Analysis. The overarching objective of this project is to develop the first fully integrated process that can convert a lignocellulosic feedstock (e.g., corn stover) efficiently and cost effectively to a mix of hydrocarbons ideally suited for blending into jet fuel. The proposed project will investigate the integration of Virent Energy System's novel aqueous phase reforming (APR) catalytic conversion technology (BioForming) with deconstruction technologies being investigated by NREL at the 1-500 L scale. Corn stover was chosen as a representative large volume, sustainable feedstock.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Fluoride salt static freezing study
Molten salt reactor designs such as the FHR must consider the safety implications of freezing, requiring the development of thermal hydraulics models that account for freezing behavior. Pipe models that couple heat transfer, fluid dynamics, and phase change physics will require verification and validation. A static freezing study is being conducted to provide an initial set of validation data with LiF-BeF{sub 2} (FLiBe). The study will also be performed with LiF-NaF-KF (FLiNaK) in order to quantify the distortion that arises from using FLiNaK as a non-toxic surrogate salt for thermal-hydraulic studies. In order to develop the numerical model, accurate inputs for the thermal hydraulic properties of the two salts of interest need to be measured near the freezing point. For this reason, a series of three experiments including Differential Scanning Calorimetry (DSC) measurements, the Density Measurement Experiment, and the Static Freezing Experiment are being conducted to determine these thermo-physical properties at temperatures near the freezing point. The Static Freezing Experiment is also designed to determine the degree of supercooling that FLiBe and FLiNaK experience. Supercooling is a temperature depression below the freezing point that the liquid experiences before freezing initiates. Increased supercooling in a liquid flowing through a pipe leads to increased dendritic freezing and an increased likelihood of pipe blockage and freeze-shut. Based on previous research on supercooling in water and non-fluoride salts, supercooling is likely affected most strongly by cooling rate and sample size (as well as salt purity). No data has been generated previously on supercooling in fluoride salts such as FLiBe and FLiNaK. The results of this set of DSC, Density Measurement and Static Freezing experiments will be used in an ongoing fluoride salt freezing study being conducted to develop pipe freezing models for molten salts to be used in safety analysis. The thermal hydraulic properties measured in this study will serve as inputs for all future models. With the supercooling behavior of both salts quantified, it can be assessed whether supercooling must be included in future thermal hydraulic models. The validated Static Freezing Experiment model can then serve as the framework for a pipe freezing model and eventually a 1D system code.
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
Numerical Study of Coupled Water and Vapor Flow, Heat Transfer, and Solute Transport in Variably-Saturated Deformable Soil During Freeze-Thaw Cycles
As climate change intensifies, soil water flow, heat transfer, and solute transport in the active, unfrozen zones within permafrost and seasonally frozen ground exhibit progressively more complex interactions that are difficult to elucidate with measurements alone. For example, frozen conditions impede water flow and solute transport in soil, while heat and mass transfer are significantly affected by high thermal inertia generated from water-ice phase change during the freeze-thaw cycle. To assist in understanding these subsurface processes, the current study presents a coupled two-dimensional model, which examines heat conduction-convection with water-ice phase change, soil water (liquid water and vapor) and groundwater flow, advective-dispersive solute transport with sorption, and soil deformation (frost heave and thaw settlement) in variably saturated soils subjected to freeze-thaw actions. This coupled multiphysics problem is numerically solved using the finite element method. The model's performance is first verified by comparison to a well-documented freezing test on unsaturated soil in a laboratory environment obtained from the literature. Then based on the proposed model, we quantify the impacts of freeze-thaw cycles on the distribution of temperature, water content, displacement history, and solute concentration in three distinct soil types, including sand, silt and clay textures. The influence of fluctuations in the air temperature, groundwater level, hydraulic conductivity, and solute transport parameters was also comparatively studied. The results show that (a) there is a significant bidirectional exchange between groundwater in the saturated zone and soil water in the vadose zone during freeze-thaw periods, and its magnitude increases with the combined influence of higher hydraulic conductivity and higher capillarity; (b) the rapid dewatering ahead of the freezing front causes local volume shrinkage within the non-frozen region when the freezing front propagates downward during the freezing stage and this volume shrinkage reduces the impact of frost heave due to ice formation. This gradually recovers when the thawed water replenishes the water loss zone during the thawing stage; and (c) the profiles of soil moisture, temperature, displacement, and solute concentration during freeze-thaw cycles are sensitive to the changes in amplitude and freeze-thaw period of the sinusoidal varying air temperature near the ground surface, hydraulic conductivity of soil texture, and the initial groundwater levels. Our modeling framework and simulation results highlight the need to account for coupled thermal-hydraulic-mechanical-chemical behaviors to better understand soil water and groundwater dynamics during freeze-thaw cycles and further help explain the observed changes in water cycles and landscape evolution in cold regions.
54 ENVIRONMENTAL SCIENCES↗
Soil pore network response to freeze-thaw cycles in permafrost aggregates
This dataset contains data used for the paper "Pore network response to freeze-thaw cycles in permafrost aggregates". The Related References field will be updated with a full citation when available.Climate change in Arctic landscapes may increase freeze-thaw frequency within the active layer as well as newly thawed permafrost. A highly disruptive process, freeze-thaw can deform soil pores and alter the architecture of the soil pore network with varied impacts to water transport and retention, redox conditions, and microbial activity. Our objective was to investigate how freeze-thaw cycles impacted the pore network of newly thawed permafrost aggregates to improve understanding of what type of transformations can be expected from warming Arctic landscapes. We measured the impact of freeze-thaw on pore morphology, pore throat diameter distribution, and pore connectivity with X-ray computed tomography (XCT) using six permafrost aggregates with sizes of 2.5 cm3 from a mineral soil horizon (Bw; 28-50 cm depths) in Toolik, Alaska. Freeze-thaw cycles were performed using a laboratory incubation consisting of five freeze-thaw cycles (-10˚C to 20˚C) over five weeks. Our findings indicated decreasing spatial connectivity of the pore network across all aggregates with higher frequencies of singly connected pores following freeze-thaw. Water-filled pores that were connected to the pore network decreased in volume while the overall connected pore volumetric fraction was not affected. Shifts in the pore throat diameter distribution were mostly observed in pore throats ranges of 100 microns or less with no corresponding changes to the pore shape factor of pore throats. Responses of the pore network to freeze-thaw varied with aggregate, suggesting that initial pore morphology may play a role in driving freeze-thaw response. Our research suggests that freeze-thaw alters the microenvironment of permafrost aggregates during the incipient stage of deformation following permafrost thaw, impacting soil properties and function in Arctic landscapes undergoing transition. This dataset contains a compressed (.zip) archive of the data and R scripts used for this manuscript. The dataset includes files in .csv format, which can be accessed and processed using MS Excel or R. This archive can also be accessed on GitHub at https://github.com/Erin-Rooney/XCT-freezethaw (DOI: 10.5281/zenodo.5816355).
54 ENVIRONMENTAL SCIENCES↗
An Innovative Zero-Liquid Discharge Intermediate-Cold-Liquid Eutectic-Freeze Desalination System
A novel freeze desalination technology is presented for purification of water produced from various industrial processes, including oil and gas extraction. The main innovative idea is introducing a water-immiscible intermediate-cold-liquid (ICL) medium which absorbs the cold from a refrigeration cycle and transfers it to a freezing chamber where it is mixed with brine. The cold ICL enters the freezing chamber at temperatures between -10°C to -30°C. Precooled brine in injected into the freezing chamber and pure water freezes out of the brine upon mixing with the ICL. The rate of freezing inside the chamber is controlled by adjusting the flow rate of the cold ICL relative to the inlet brine. Both eutectic freeze and non-eutectic freezing are possible by controlling the temperature of the freezing chamber. The solid-liquid slurry created in the freezing chamber flows to a filter separation unit after passing through a separation column. The ice crystals are separated from the liquid by a rotary filter device. The collected ice is rinsed by a centrifugal unit. The rinsed ice is melted to produce fresh water. The developed technology resolves the issues common to current freeze-desalination systems while offering superior heat transfer performance ascribed to direct-contact between the cooling medium and the brine in addition to producing solid salt and pure water. The system operates under atmospheric pressure. The low operation temperature minimizes the corrosion issues common in systems exposed to brine. Also, due to the low operating temperature, there are no concerns about evaporation of volatile organics from the produced water during the treatment. The developed technology effectively eliminates the use of chemicals for pretreatment of brine. The system can be constructed from commercially available components. Extensive testing using a lab-scale prototype by using synthetic brine and actual produced water with TDS values from 50,000 ppm to 300,000 ppm showed that freshwater could be achieved with relatively small dependency on the quality of the input brine. The quality of the treated water was found to be mainly a function of the duration of the centrifugal process. Treated water with TDS as low as 200 ppm could be achieved in the tests. Thermo-economic modeling coupled with system level thermochemical process model were developed for prediction of the LCOW. The LCOW was predicted to be $\$$0.50 to $\$$0.90 per barrel of produced water. The potential markets for deployment of the technology are the oil and gas, in-land thermoelectric powerplants, RO desalination plants, and mining industry.
29 ENERGY PLANNING, POLICY, AND ECONOMY↗
Freeze Technology for Nuclear Applications - 13590
Freezing of soil materials is a complicated process of a number of physical processes: - freezing of pore water in a thermal gradient, - cryogenic suction causing water migration and - ice formation expanding pores inducing frost heave. Structural changes due to increase of effective stress during freezing also take place. The over consolidation gives a powerful dewatering/drying effect and the freeze process causes separation of contaminates. Artificial ground freezing (AGF is a well established technique first practiced in south Wales, as early as 1862. AGF is mostly used to stabilize tunnels and excavations. During the last ten years underwater applications of freeze technologies based on the AGF have been explored in Sweden. The technology can, and has been, used in many different steps in a remediation action. Freeze Sampling where undisturbed samples are removed in both soft and hard sediment/sludge, Freeze Dredging; retrieval of sediment with good precision and minimal redistribution, and Freeze Drying; volume reduction of contaminated sludge/sediment. The application of these technologies in a nuclear or radioactive environment provides several advantages. Sampling by freezing gives for example an advantage of an undisturbed sample taken at a specified depth, salvaging objects by freezing or removal of sludges is other applications of this, for the nuclear industry, novel technology. (authors)
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Sodium Freezing and Remelting Tests in FY 2018
In FY 2017 and FY 2018, a total of thirteen tests were successfully performed in the Sodium Freezing and Remelting test facility. Each new test was carefully designed based upon the results and findings of the previous test to investigate the effects of different factors on the sodium freezing phenomena, including dissolved Ar cover gas versus vacuum, test section cooling rate during freezing, different freezing patterns (e.g., from the free surfaces inward toward the center versus from the center toward the free surfaces), and Ar cover gas pressure. The freezing results were found to depend upon a combination of phenomena. As more tests were conducted and lessons learned, the conduct of the tests improved. In particular, the last three experiments, Tests 11 through 13, may be singled out as providing representative data under well controlled conditions. The maximum stresses arising from sodium freezing are measured to be quite mild. In the tests, a maximum strain change of 60 radial micro strains was measured, equivalent to a stress/negative pressure of 77 psi. This mild maximum stress is thought to reflect the low yield stress of solid sodium near the freezing temperature. Evidence for yielding of solid sodium is provided by the visual observation of a depression in the frozen sodium free surface inside of the sodium reservoir in one test. It is thought that contraction of sodium in the test section during freezing pulled downward on the frozen sodium at the free surface creating the depression. The authors are not aware of any data for the yield stress of solid sodium or the stress versus strain behavior of solid sodium (sodium is not a structural material). It is thus not possible to directly compare with the solid sodium yield strength. However, stress versus strain data at different temperatures up to the freezing temperature are available for solid lithium which is also a alkali metal and has a low yield strength similar to the maximum stresses determined from the Sodium Freezing and Remelting tests providing support for the interpretation of the results in terms of yielding of solid sodium. This is a good result for Sodium-Cooled Fast Reactors and sodium facilities. The maximum stress due to frozen sodium pulling inward upon a structural wall wetted by sodium and to which the sodium adheres will be limited by the low sodium yield stress. Argon has a significant solubility in sodium. Cavitation due to nucleation of dissolved argon can offset the effects of sodium thermal contraction and alleviate the formation of stress/negative pressure. This is also a good result for Sodium-Cooled Fast Reactors and sodium facilities that operate with an argon cover gas. In the tests, it was found that due to the cavitation, the maximum measured strain change during sodium freezing was limited to 10 axial micro strains, or equivalently 55 psi of negative pressure.
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
A comprehensive laboratory study on the immersion freezing behavior of illite NX particles. A comparison of 17 ice nucleation measurement techniques
Immersion freezing is the most relevant heterogeneous ice nucleation mechanism through which ice crystals are formed in mixed-phase clouds. In recent years, an increasing number of laboratory experiments utilizing a variety of instruments have examined immersion freezing activity of atmospherically relevant ice-nucleating particles. However, an intercomparison of these laboratory results is a difficult task because investigators have used different ice nucleation (IN) measurement methods to produce these results. A remaining challenge is to explore the sensitivity and accuracy of these techniques and to understand how the IN results are potentially influenced or biased by experimental parameters associated with these techniques. Within the framework of INUIT (Ice Nuclei Research Unit), we distributed an illite-rich sample (illite NX) as a representative surrogate for atmospheric mineral dust particles to investigators to perform immersion freezing experiments using different IN measurement methods and to obtain IN data as a function of particle concentration, temperature ( T ), cooling rate and nucleation time. A total of 17 measurement methods were involved in the data intercomparison. Experiments with seven instruments started with the test sample pre-suspended in water before cooling, while 10 other instruments employed water vapor condensation onto dry-dispersed particles followed by immersion freezing. The resulting comprehensive immersion freezing data set was evaluated using the ice nucleation active surface-site density, n s , to develop a representative n s ( T ) spectrum that spans a wide temperature range (-37 °C < T < -11 °C) and covers 9 orders of magnitude in n s . In general, the 17 immersion freezing measurement techniques deviate, within a range of about 8 °C in terms of temperature, by 3 orders of magnitude with respect to n s . In addition, we show evidence that the immersion freezing efficiency expressed in n s of illite NX particles is relatively independent of droplet size, particle mass in suspension, particle size and cooling rate during freezing. A strong temperature dependence and weak time and size dependence of the immersion freezing efficiency of illite-rich clay mineral particles enabled the n s parameterization solely as a function of temperature. We also characterized the n s ( T ) spectra and identified a section with a steep slope between -20 and -27 °C, where a large fraction of active sites of our test dust may trigger immersion freezing. This slope was followed by a region with a gentler slope at temperatures below -27 °C. While the agreement between different instruments was reasonable below ~ -27 °C, there seemed to be a different trend in the temperature-dependent ice nucleation activity from the suspension and dry-dispersed particle measurements for this mineral dust, in particular at higher temperatures. For instance, the ice nucleation activity expressed in n s was smaller for the average of the wet suspended samples and higher for the average of the dry-dispersed aerosol samples between about -27 and -18 °C. Only instruments making measurements with wet suspended samples were able to measure ice nucleation above -18 °C. A possible explanation for the deviation between -27 and -18 °C is discussed. Multiple exponential distribution fits in both linear and log space for both specific surface area-based n s ( T ) and geometric surface area-based n s ( T ) are provided. These new fits, constrained by using identical reference samples, will help to compare IN measurement methods that are not included in the present study and IN data from future IN instruments.
54 ENVIRONMENTAL SCIENCES↗