Sodium-potassium Alloy Research Articles

Pulsating Heat Pipe Performance Modeling with Liquid Metal Coolants Under Hypersonic Aerothermal Heating

Hypersonic heating loads concentrate at leading-edge compression areas to create excessively high local temperatures and thermally driven stresses. The fast and reliable thermal dispersion of heat pipes with significantly high thermal conductance can alleviate these localized thermal stiffness problems. The pulsating heat pipe (PHP) holds numerous advantages when compared to capillary, constant-conductance heat pipes for hypersonic thermal management applications, primarily because they lack a wicking structure. This paper numerically investigates thermal performances of a four-turn C103 niobium alloy PHP operating with lithium, potassium, sodium, and a eutectic sodium–potassium alloy (NaK-78) when exposed to heating conditions relevant to the hypersonic environment, investigating flight Mach numbers ranging from 6 to 8 and dynamic pressures ranging from 40 to 44 kPa. The robust thermofluidic properties of liquid metals, along with the powerful fluid pulsation induced in the PHP, can provide significant thermal transport from hot stagnant regions of the leading edge to the cooler trailing surfaces. Potassium showed superior thermal performance when compared to other liquid metal coolants under the presently tested conditions, with overall PHP thermal conductance as high as 34 W/K predicted for Mach 8 flight conditions. In contrast, sodium was associated with startup difficulties in the PHP; this paper attributes this to its significantly larger thermal conductivity, which can limit the vapor pressure difference over the liquid slug lengths. These predictions indicate an overall latent heat transfer dominance of around 70–95% in liquid metal PHPs.

Stabilizing electrode-electrolyte interface via crown ether-containing selective coating for dendrite-free Na-K anode-based solid-state sodium batteries

Sodium-potassium (Na-K) alloy is considered a promising anode material due to its liquid characteristics at room temperature. However, unstable interfaces and disastrous ion exchange between Na-K alloy anodes and solid-state Na electrolytes (SSNEs) have hindered further applications of solid-state Na batteries (SSNBs) based on Na-K anodes. In this work, a specially designed Na+/K+ selective gel coating with 15-crown 5-ether (15C5) is constructed on the beta-alumina solid electrolyte (BASE) to achieve a good match with Na-K anodes. The coordination of 15C5 with Na+ forms Na+-permeable complexes and affects the electrolyte solvation structure in the gel coating, resulting in the formation of solid electrolyte interfaces (SEIs) that lack K+ channels and are organically rich, which effectively inhibit the ion exchange and stabilize the interface. Benefitting from the selective coating, the cycling lifetime of the Na-K|Gel-BASE-Gel|Na-K symmetric cell reaches over 1000 h, and the Na-K|Gel-BASE-Gel|Na3V2(PO4)3 full cell exhibits great long-cycle stability and excellent rate performance at room temperature. This work extends the application of Na-K anodes and provides a suggestion for achieving high-performance SSNBs at room temperature.

Influence of location of twin-adiabatic blocks on magnetohydrodynamics-based double-diffusive convection and entropy generation for a liquid metal

This research deals with a rectangular cavity encompassing two adiabatic rectangular and impermeable obstacles at various positions. This study serves as a platform to explore the interplay between diverse flow-governing parameters, such as the buoyancy ratio (N = −1, 0, and +1), Hartmann number (Ha = 0, 50, and 100), Lewis number (Le = 1, 5, and 10), Rayleigh number (Ra = 103 and 104), and geometric arrangements of twin-blocks (C1, C2, and C3) to help in developing insights into such complex transport phenomenon driven under the influence of buoyancy and concentration. The arrangements are chosen such that C1 and C3 represent the off-center position of the first obstacle, while C2 represents the in-line position with the second obstacle. The influence of liquid sodium–potassium alloy (Pr = 0.054) on fluid flow, heat, and mass transfer, and entropy generation characteristics due to double-diffusive natural convection in the twin obstacle-filled rectangular enclosure are observed using the lattice Boltzmann method. The results reveal that the maximum amount of heat and mass transfer occurs at the C2 position, making it the most efficient for heat and mass transfer among all. In contrast, the C2 configuration is a thermodynamically inefficient arrangement as entropy generation is maximum, while the C3 configuration is obtained to be more efficient thermodynamically. Furthermore, the results reveal that the average total entropy generation is directly related to the Lewis number, while it has an inverse relation with the Hartmann number.

Liquid Na-K alloy is not viable anode material for High-Performance Na-Ion batteries

Liquid sodium–potassium alloy NaxK100-x at. % (≈14 < x < 70 at room temperature) has been proposed as a dendrite-free liquid metal anode for Na-ion batteries. Nevertheless, controversy surrounds the use of NaxK100-x as a Na-ion battery anode due to the presence of the two competitive redox-active species, Na/Na+ and K/K+. To resolve this ongoing controversy, we use x-ray diffraction (XRD) and cryogenic-focused ion beam/scanning electron microscopy (cryo-FIB/SEM) to investigate liquid Na50K50 electrodes cycled in symmetric cells using Na-ion electrolytes. We find that the reaction overpotential abruptly increases after ≈ 40 cycles. Cryo-FIB/SEM reveals the precipitation of K salts, which confirms that K/K+ species are redox-active in Na-ion electrolytes. Such an effect progressively leads to irreversible leaching of K from the initial liquid Na50K50 composition, resulting in a loss of liquid metal properties. Consequently, our results suggest that NaxK100-x cannot sustainably function as a liquid metal anode in Na-ion batteries.

Influence of Joule heating and magneto-hydrodynamic on double diffusion mixed convection in a cavity with liquid sodium-potassium alloy and discrete thermosolutal source

Researchers in the biomedical field have focused more on the application of magneto-hydrodynamics in recent years. This study examines the steady double-diffusive mixed convection characteristics in a double-sided cavity with liquid potassium alloy that exhibits a magnetic effect and Joule heating. The investigation analyzes the impact of various parameters, including Hartmann number (0 ≤ Ha ≤ 50), Joule Heating (0 ≤ J ≤ 10.0), Reynolds number (102 ≤ Re ≤ 103), Lewis number (1.0 ≤ Le ≤ 10.0), Buoyancy ratio (−4.0 ≤ N ≤ 4.0), Prandtl number (Pr = 0.054), and Richardson Number (Ri = 1.0). The results are obtained using finite volume-based numerical codes. The findings suggest that the heat and mass transfer rates increase as Re and J increase and decrease when there is an increase in Ha and N. There is a significant effect on both the Joule parameter and magnetic field on fluid and heat flow. When Joule heating is present, increasing the Le results in a 0.627 times increase in heat transfer rate and a 1.722 times increase in mass transfer rate. When Re increases, the average Nusselt number (Nuavg) and average Sherwood number (Shavg) increase 0.81 and 0.11 times, respectively.

Bismuth-based liquid metals: advances, applications, and prospects.

Bismuth-based liquid metals (LMs) are a large group of alloys with melting points slightly above room temperature. They are associated with fewer encapsulation constraints than room temperature LMs such as mercury, sodium-potassium alloys, and gallium-based alloys and are more likely to remain stable in the natural environment. In addition, their low melting point properties enable them to soften and melt via easy control. Bismuth-based alloys can also be modified with metal-based, carbon-based, and ceramic-based micro/nano particles as well as polymeric materials to create a series of novel composites owing to their outstanding functions. Based on these considerations, this review provides a comprehensive overview of bismuth-based LMs. The categories of bismuth and bismuth-based LMs are first briefly introduced to better systematize the physical and chemical properties of bismuth-based LMs. Based on these properties, bismuth-based LMs have been prepared using various methods, and this review briefly categorizes these preparation methods based on their finished forms (lumps, powders, and films). In addition, this review details the research progress of bismuth-based LMs in the fields of printed electronics, 3D printing, thermal management, biomedicine, chemical engineering, and deformable robotics. Finally, the challenges and future opportunities of bismuth-based LMs in the development process are discussed and visualized from different perspectives.

Effect of near-wall blockage on the magnetohydrodynamics-based double-diffusive convection in rectangular cavities

This research work reports the numerical investigation of magnetohydrodynamics (MHD) characteristics around the near-wall blockage for various separation distances owing to double-diffusive convection (DDC) in a rectangular cavity. The distance between the bottom wall of the cavity and the lower wall of blockage is called separation distance and it has varied from where H is the height of the cavity. The working fluid is considered as liquid metal - Sodium-Potassium alloy (). The numerical computations are conducted by using an in-house developed lattice Boltzmann method solver. The simulations are conducted for the steady-state, laminar, incompressible, and Newtonian fluid flow. The effect of NWB has been explored for a range of parameters, such as Rayleigh number and Lewis number buoyancy ratio and Hartmann number The variation and contour plots show the higher heat and mass transfer (HMT) rates for at constant Ra. As increases, HMT rates enhance. The increase in Ra, N, and Le induces multiple-cell formation inside the cavity for a given As Ha augments HMT rates get decreased monotonically. For negligible or slight variation was observed in the rate of HMT. As the obstruction between the bottom wall of the blockage and the adiabatic bottom wall of the cavity increases, shear force occurs, and the buoyancy-driven flow decreases. The outcomes of the numerical investigation are summarized in the form of empirical correlation of for Ra = and at various separation distances, which might be utilized for probable design purposes.

Suitability of NaK alloy for the sodium or potassium metal batteries: Competition between cathode size effect and ion reaction priority effect

Sodium-potassium (NaK) alloys in a specific ratio can maintain their liquid state at room temperature, rendering them dendrite-free anodes for alkali metal batteries. Nevertheless, a controversy has arisen regarding the suitability of either sodium metal batteries (NaMBs) or potassium metal batteries (KMBs) due to the presence of dual active ions in NaK. Based on the current research, there is a contradiction regarding the feasibility of making NaK anodes suitable for NaMBs through the cathode size effect (e.g., Na3V2(PO4)3), and for KMBs due to the ion reaction priority effect of K+. In this study, Na3V2(PO4)3 (NVP) cathodes are assembled into batteries with various anodes (Na, Na-rich-NaK, NaK, K-rich-NaK, and K), to investigate the dominant role of active ions in the competing process between the cathode size effect and the ion reaction priority effect. Tests and characterization results demonstrate that the ion preference reaction spontaneously displaces Na+ with K+ in the presence of K, although the cathode size effect may restrict K+ embedding and significantly reduce battery capacity. In summary, the ion reaction priority effect dictates the reactions that render NaK anodes exclusively suitable for KMBs without altering the reaction priority of K+.

Cobalt/Nitrogen Co-Doped Carbon Materials Enhance the Reaction Rate of Sodium-Potassium Alloy Electrodes.

Sodium-potassium (NaK) alloy electrodes are ideal for next-generation dendrite-free alkali metal electrodes due to their dendrite-free nature. However, issues such as slow diffusion kinetics due to the large K+ radius and the loss of active potassium during the reaction severely limit its application. Here a novel cobalt/nitrogen-doped carbon material is designed and it is applied to the construction of a NaK alloy electrode. The experimental and theoretical results indicate that the confining effect of the nitrogen-doped graphitic carbon layer can protect the cobalt nanoparticles from corrosion leaching, while the presence of Co─Nx bonds and cobalt nanoparticles provides more active sites for the reaction, realizing the synergistic effect of adsorption-catalytic modulation, lowering the K+ diffusion energy barrier and promoting charge transfer and ion diffusion. The application of this electrode to a symmetrical battery can achieve more than 1800 stable cycles under a current density of 0.4mA cm-2 and a charge/discharge specific capacity of 122.64 mAh g-1 under a current of 0.5C in a full battery. This finding provides a new idea to realize a fast, stable, and efficient application of NaK alloy electrodes.

Na–K Co‐deposition in Liquid‐Alloy Batteries Revealed by Operando Visualization

Despite the great prospects of alkali metal batteries, safety concerns associated with dendrite growth still limit their commercial applications. An attractive alternative is to use the room temperature liquid sodium–potassium alloy as the anode, which inherently prevents dendrite growth. Currently, Na–K alloy anodes allow only Na+ or K+ to be cycled, depending on the choice of electrolyte and ion selectivity of the cathode, which results in reduced energy density of the battery. Herein, the possibility of concurrent use of both Na+ and K+ ions in Na–K alloy anodes is explored, and the working mechanism by operando optical microscopy is investigated. It is found that the type of deposited metal is dictated by both salt and solvent in electrolyte. Impressively, Na–K co‐deposition is observed in KFSI‐DME electrolyte for the first time, which strongly influences the dendrite morphology and evolution. Furthermore, the current density also has a great impact on the deposition pattern, which allows dendrite‐free Na/K deposition on the liquid‐alloy anode. These findings enrich our understanding of the intricate electrochemical behaviors of Na–K binary electroactive alloy systems and offer guidance for the sufficient use of Na and K while avoiding dendrite formation in such liquid‐alloy batteries.

Investigation of the heat transfer enhancement and deterioration induced by vortex generators in low Prandtl number sodium-potassium alloy liquid

Liquid metals, being characterized by low molecular viscosity and high molecular thermal conductivity, appear to be a stupendous choice for heat transfer fluids in deep-space nuclear reactors. Nevertheless, because of space nuclear reactor weight and volume constraints, the heat transfer capability of the heat exchanger must be substantially improved for a deeper space exploration mission. In this study, the influence of the vortex generator applied to the liquid metal was investigated to further promote the heat transfer capability of the liquid metal. And the thermo-fluid behaviors of the sodium-potassium alloy (NaK-78) are compared among the channel with the Body-Centered Cubic (BCC) lattice array, the rectangular ring rib array, and the Kagome lattice array under identical porosity. The numerical results indicate that the heat transfer deterioration phenomena occurred in the case of rectangular ring rib channel, which is a relatively rare occurrence in conventional fluids with the local Nu number even being lower than that of the smooth channel at the same location. Therefore, the rectangular ring rib should be carefully considered and evaluated when it is applied to heat transfer enhancement in NaK alloy fluid. The Kagome structure and the BCC structure could effectively promote the heat transfer performance of the NaK alloy fluid by means of the induced composite vortex system. In comparison to the smooth channel, the average Nu of the cases with the Kagome array and the BCC array yield 17.26–37.32% and 51.98–78.85% higher, respectively.

Preliminary conceptual design of an electronuclear system for space applications

The purpose of this paper is to present a preliminary conceptual design of a nuclear power system for space applications. This design was produced within the framework of a collaboration between CNES and CEA. The targeted electrical power of the system is 10 kWe for a period of at least 10 years. The scalability towards larger (30 kWe) and lower (about 1 kWe) power has been investigated. The system must be technologically “affordable” and robust over a 10-year horizon, which de facto eliminates the choice of too innovative and unqualified technologies in conditions representative of the missions; the system must be able to be launched in Ariane 6 while respecting the launcher mass and size capacities. Given the intermediate power level targeted and the potential use of the system on the Moon or Mars, the CEA favored design options associated with a compact and monolithic radiator (allowing it to be landed) rather than minimizing the system mass. Taking into account the desired characteristics for the nuclear power system, the CEA proposes main conceptual design features which includes: a thermal spectrum core whose fuel is UO2 enriched to 19.75% in U235, zirconium fuel cladding, a zirconium hydride (ZrH2) moderator, and a beryllium reflector. The proposed shield is made of tungsten and lithium hydride (LiH). A core cooling system made up of 150 steel heat pipes operating with a sodium–potassium alloy (NaK) has been pre-designed and a thermoelectric energy converter made up of SiGe thermo-elements (hot temperature of 950 K and cold temperature of 700 K) generates electrical power. A “hot” carbon composite radiator lined with titanium NaK heat pipes rejects the heat of the system. This system has intrinsic redundancies conferred by the heat pipes and the large number of thermo-elements of the converter as well as high passivity, in particular in its ability to adapt its power to electricity demand. In its version limited to 10 kWe, the system whose height is about 5 m, enables to keep a height of 13 m for a payload to be launched in the Ariane 6 fairing and its mass is estimated at about 2 tons. To access a version of the system capable of producing 30 kWe, an additional mass estimated at around 1 ton is to be expected as well as a lower useful height in the fairing under the system, which would then be 10 m.

Experimental study on the effects of filling ratios on heat transfer characteristics of liquid metal high-temperature oscillating heat pipes

The liquid metal high-temperature oscillating heat pipe (LMHOHP) is a kind of oscillating heat pipe with liquid metal as the working fluid, which can work efficiently in high-temperature environments over 500 ℃. In this paper, in order to master the effects of the filling ratio on the performance of the LMHOHPs, the start-up performance, the flow state, and the heat transfer performance of LMHOHPs were studied by experiments. The working fluid of LMHOHPs was sodium-potassium alloy with the potassium mass fraction of 78%. Under the input powers of 1500–3500 W and the inclination angles of 0–90°, LMHOHPs with filling ratios of 11–88% were tested. The experimental results showed that: (1) The LMHOHPs with filling ratios of 22–80% could successfully start up, and the heat transfer process was carried out by oscillation flow of the working fluid. The start-up mode varies with the filling ratio, and the start-up temperature increased with the increasing filling ratio. (2) With the filling ratios of 35–64%, the flow states of the LMHOHPs could change from the oscillation flow to the unidirectional circulation flow, and the heat transfer performance was significantly enhanced. With the increase of filling ratio, the required input power at the transition of the flow state decreased. (3) When the inclination angles were 30–90°, the thermal resistance of LMHOHPs decreased firstly and then increased with the filling ratio, and the achieved minimum thermal resistance was 0.081 ℃/W when the filling ratio was 48%. However, when the inclination angle was 0°, the thermal resistance of LMHOHPs monotonically increased with the filling ratio.

Study into the physical chemistry and technology of alkali liquid metal coolants for nuclear and thermonuclear power plants

It is shown that, as the result of developing alkali liquid metal coolants, including sodium, eutectic sodium-potassium alloy, lithium and cesium, the scientific basis has been established for their application in nuclear power. The paper presents data from investigations of thermophysical, neutronic and physicochemical properties and characteristics of various alkali liquid metal coolants, the content of solid-phase and dissolved impurities in coolants, mass transport of impurities in circulation circuits with alkali liquid metal coolants, development of systems for removal of impurities, and control of the content of impurities in alkali liquid metal coolants. Alkali liquid metal coolants are considered as a part of a system that includes a structural material in contact with the coolant, and a gas space that compensates for the thermal expansion of the coolant. The state of the system is defined by the physicochemical properties of the system’s components. And the coolant and the structural materials also represent subsystems consisting of a base material, a coolant and impurities contained both in the material and in the coolant. It has been shown that each alkali liquid metal coolant has its own set of impurities that define its technology. It depends on the physicochemical properties of the solution of the structural material impurities and components in the coolant. Objectives have been formulated for investigating further alkali liquid metal coolants, as stemming from the need to improve the efficiency, environmental friendliness, reliability and safety, and for extending the life of nuclear power plants in operation or under design. Alkali liquid metals are promising candidate materials for being used in thermonuclear power not only as the coolant but also as the tritium breeding medium. These include, first of all, lithium and its eutectic alloy with lead (17 at. % of lithium). The possibility for using lithium or a lithium-lead alloy as a coolant in the blanket of the international thermonuclear power reactor is compared.

Comparison study of thermoclinic heat storage tanks using different liquid metals for concentrated solar power

Liquid metals are good potential heat transfer materials for thermoclinic heat storage (THS) systems and will play an important role in the next generation solar thermal power system with higher operating temperature. This paper presents a comparative research work on the charging, discharging and mechanical performances of THS tanks based on four different liquid metal materials, which are lead (Pb), lead-bismuth alloy (PbBi), sodium (Na) and sodium-potassium alloy (NaK). The analysis results indicate that for both the charging and discharging processes, the lead-based THS tank can have the shortest operating duration, largest charging and discharging quantities (9.78 × 109 J and 9.21 × 109 J) as well as the highest discharging efficiency (94.17%), revealing its best operating performance. Relatively acceptable operating performances of lead-bismuth-based and sodium-based THS tanks are also demonstrated. Furthermore, in contrast with other three liquid metals, the lead-based THS tank also has the best mechanical performance. It has the smallest peak maximum mechanical stress of the steel wall (58.6 MPa). In summary, the lead-based THS tank has both the best heat storage and mechanical performances.

Effect of the aspect ratio of the shallow enclosure and built‐in rectangular blockage on MHD double‐diffusive free convection subjugated to non‐uniform boundary conditions

AbstractIn this study, the lattice Boltzmann method is used to explore the double‐diffusive natural convection within a shallow enclosure with a built‐in rectangular blockage at its geometric center. The enclosure is exposed to an external magnetic field. One of the enclosure walls is subjected to linearly/sinusoidal heating and concentration conditions. The rectangular blockage is at higher temperature and concentration conditions. Numerical experimentation is executed for a range of parameters such as Rayleigh number , Lewis number , buoyancy ratio , aspect ratio of the enclosure , aspect ratio of the built‐in blockage , and Hartmann number . The working fluid is assumed to be liquid metal (sodium–potassium alloy, ). The complex interaction of flow parameters with the nonuniform heating and concentration conditions has been explored. Higher heat and mass transfer (HMT) rates are noticed for the sinusoidal temperature and concentration profile compared to linear for a given . and showed enhancement by , and for sinusoidal temperature and concentration profile of the enclosure as compared to linear for . The increase in the blockage and the enclosure aspect ratio shows augmentation in the HMT rate. The consequences of the study are also summarized in terms of empirical correlations of the and numbers showing functional dependence on the considered range of parameters.

Radical Covalent Organic Frameworks Associated with Liquid Na-K toward Dendrite-Free Alkali Metal Anodes.

Liquid sodium‐potassium (Na‐K) alloy has the characteristics of high abundance, low redox potential, high capacity, and no dendrites, which has become an ideal alternative material for potassium/sodium metal anodes. However, the high surface tension of liquid sodium potassium alloy at room temperature makes it inconvenient in practical use. Here, the Na‐K as reducing agent treats with hydrazone linkages of covalent organic frameworks (COFs) and obtain the carbon‐oxygen radical COFs (COR‐Tf‐DHzDM‐COFs). The preparation method solves the problems that the preparation process of the traditional Na‐K composite anode is complex and has high cost. The structures of the COR‐Tf‐DHzDM‐COFs are characterized by X‐ray diffraction （XRD), fourier transform infrared (FT‐IR), electron paramagnetic resonance (EPR), and solid‐state NMR measurements. It is the first time that carbon‐oxygen radical COFs from bulk COFs are constructed by one‐step method and the operation is flexible, convenient, and high rate of quality, which is suitable for big production and widely used. The cycle stability of the composite Na‐K anode is improved, which provides a new idea for the design of high‐performance liquid metal anode.

Experimental study on the effects of sodium and potassium proportions on the heat transfer performance of liquid metal high-temperature oscillating heat pipes

Liquid metal high-temperature oscillating heat pipes (LMHOHPs) are highly efficient heat transfer devices which can work in high temperature environments above 500 °C. In this paper, LMHOHPs with different proportions of sodium-potassium alloy (hereinafter referred to as NaK) as working fluids were developed, and their start-up and heat transfer performance was investigated experimentally. 310S stainless steel with an inner diameter of 6mm was employed as the pipe material, and the filling ratio was kept as 50%. Under the conditions of input powers 1500∼3500 W and inclination angles 0°∼90°, LMHOHPs with five proportions of NaK (namely, 0, 10, 46, 78 and 100 wt.% of potassium) as working fluids were tested. The results showed that: (1) The wettability between NaK and 310S stainless steel was poor, but it was improved with the increase of temperature and potassium mass fraction. At 350 °C, The contact angles of NaK (K100%) and NaK (K78%) were 72.3° and 81.1°, respectively, which meant that the liquid metal changed from non-wetting state to wetting state. (2) Except that the LMHOHP with NaK (K0%) could not start up at the inclination angle of 0°, the five LMHOHPs could start up successfully and transfer heat through oscillating motion at all inclination angles and input powers. (3) When the heat flux exceeded 4.56 × 106W/m2, the flow patterns of LMHOHPs with NaK (K10%), NaK (K46%), NaK (K78%) and NaK (K100%) changed from oscillating motion to stable unidirectional circulating flow, which significantly improved their heat transfer performance. (4) Due to the influences of saturated vapor pressure gradient, viscosity and wettability, the heat transfer performance of LMHOHPs increased with the growth of potassium mass fraction. The minimum thermal resistance of the LMHOHP with NaK (K100%) was 0.071 °C/W at the input power of 3528 W and the inclination angle of 90°. This study could provide guidance for the working fluids selection of oscillating heat pipes in high temperature environments.

Liquid Na/K Alloy Interfacial Synthesis of Functional Porous Carbon at Ambient Temperature.

The functional groups in porous carbon generally suffer a severe loss during the high-temperature carbonization. Instead, the low-temperature synthesis of carbon featuring porous structures and abundant functional groups is not only a solution that evades the pitfalls of pyrolysis but also is of significance for the development of synthetic methodology. Herein, a liquid metal interfacial engineering strategy is reported for the synthesis of porous carbon using CCl4 as the carbon precursor and sodium-potassium alloy (NaK) as the reducing agent, which is superior to traditional synthetic methods because it enables the engineering of a highly active liquid metal alloy microemulsion to directly generate porous carbon at ambient temperature. As synthesized porous carbon featured abundant carbon-chlorine bonds can be tandem-grafted with imidazole and 1,2-dibromoethane to achieve a CO2 cycloaddition catalyst, which exhibits excellent catalytic activity, in addition to exceptional stability.

Double-diffusive convection in a rectangular cavity subjected to an external magnetic field with heated rectangular blockage insertion for liquid sodium–potassium alloy

A two-dimensional, steady-state, laminar, double-diffusive convection within the rectangular cavity containing heated rectangular blockage at its geometric center has been explored by the lattice Boltzmann method. The research work is focused on determining the combined influence created by a magnetic force and double-diffusive convective characteristics in the shallow cavity (length &amp;gt; height) and rectangular blockage (width &amp;gt; height). In particular, the influence of various pertinent parameters, such as the aspect ratio of the cavity (AR = 1, 2, and 4), the aspect ratio of the heated blockage (ar = 1, 2, and 4), Lewis number (Le = 2, 5, and 10), Prandtl number (Pr) = 0.054, Rayleigh number (Ra = 103, 104, and 105), Hartmann number (Ha = 0, 50, and 100), and the buoyancy ratios (N = −2, 0, and 2), on the double-diffusive convection accompanied by magnetohydrodynamics characteristics has been elaborated. The working fluid in the cavity is considered to be a liquid metal-sodium–potassium alloy (Pr = 0.054). The results indicated the augmentation in Le leads to the formation of multi-cell zones within the cavity. For N &amp;lt; 0, the direction of fluid flow, thermal, and concentration patterns is reversed as for N &amp;gt; 0. Denser crowding of temperature and concentration contour lines along the block was noticed for N = 2 than N = −2 for a given Ra. The total Nusselt (Nutotal) and Sherwood number (Shtotal) decreases with a decrease in N. The heat and mass transfer rates enhance with augmentation in both cavity and blockage aspect ratios.