Conductivity Ratio Research Articles

A Promising Radiation Thermal Protection Coating Based on Lamellar Porous Ca‐Cr co‐Doped Y3NbO7 Ceramic

AbstractDissipation of heat efficiently from a hot object via radiation while minimizing the inward heat conduction is the key requirement of radiation thermal protection. In this study, a Ca‐Cr co‐doped Y3NbO7 coating with lamellar porous structure is fabricated, which shows an ultra‐low thermal conductivity (<0.7 W m−1 K−1) and near‐unity emissivity (>0.9) across a broad wavelength range of ≈1–24 µm. This record high emissivity to thermal conductivity ratio (≈1.3) is experimentally and theoretically revealed from a multi‐scale perspective. The diffusoin‐mediated thermal conduction feature of niobates combined with lamellar porous structure of the coating reduces its thermal conductivity to an impressive 0.5 W m−1 K−1 at 25 °C, surpassing the theoretical amorphous limitation of 0.72 W m−1 K−1. Experiments and FDTD calculation results demonstrate that the intrinsic emissivity dips at shallow extinction wavelengths (1 and 8 µm) and strong phonon‐polariton resonances wavelengths (>13 µm) can be effectively compensated by the multiple scattering/absorption and gradual modulation of conical shape/effective refractive index induced by surface micro‐protrusion structures, respectively. Furthermore, the coating exhibits robust mechanical and thermal stability with a high bonding strength (18.3 MPa) and thermal expansion coefficient (≈11 × 10−6 K−1 at 1200 °C) comparable to YSZ, showing great potential in the radiation thermal protection field.

Rheological characteristics and thermal studies of EG based Cu:ZnO hybrid nanofluids for enhanced heat transfer efficiency

The present work describes an experimental investigation of Cu-doped ZnO–EG hybrid nanofluids for better viscous nature and thermal efficiency in cooling systems. The initial phase involves synthesizing copper (Cu) doped zinc oxide (ZnO) nanoparticles using chemical precipitation method. The structural and morphological properties of these nanoparticles are determined using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Thermo-physical measurements are conducted to analyze the viscosity and thermal conductivity of Cu-doped ZnO nanofluids based on ethylene glycol (EG) at varying particle concentrations (ranging from 0.01 wt% to 0.08 wt%) with various temperature ranges of 298 K to 328 K. The observed rheological properties showed that the viscosity of tested Cu-doped ZnO-EG nanofluids exhibited non-Newtonian shear-thinning behavior due to the alignment of nanoparticle agglomerates with increasing shear rate. Similarly, the thermal properties of the prepared Cu:ZnO-EG nanofluids are examined, demonstrating a smooth increase in thermal conductivity with changes in particle concentration and temperature. The thermal conductivity ratio of the nanofluids suggests that the newly developed hybrid nanofluids exhibit superior heat transfer characteristics.

Polyelectrolyte Membranes Based on Nafion/Chitosan Blends for Direct Methanol Fuel Cell Application

In this study, polyelectrolyte membranes (PEMs) were fabricated by blending chitosan and Nafion with various compositions for direct methanol fuel cell (DMFC) application. The incorporation of Nafion caused increasing the glass transition temperature (Tg), as well as decreasing the crystallinity of chitosan based matrix, which has roots in the attractive interaction between –SO3H groups in Nafion and –NH2 groups in chitosan structure. In addition, the proton conductivity, as well as the methanol permeability of the studied membranes increased with an increase in the loading weight of Nafion. The selectivity parameter (the ratio of proton conductivity to methanol permeability) of the membrane containing 25 wt% of Nafion was comparable to neat Nafion. In parallel, the results of the DMFC performance test showed a maximum power density of 39 mW cm−2 at 319 mA cm−2 current density (at 5 M methanol concentration and 75 °C) for the mentioned membrane which is near to that for recast Nafion. The results showed that the chitosan/Nafion complex can be considered as a PEM for DMFC application.

Natural convection in a differentially heated cavity filled with a Brinkman bidisperse porous medium

PurposeThe purpose of this work is the study of the steady free convection in a square differentially heated cavity filled by a Brinkman bidisperse porous medium. An appropriate mathematical model considering the Brinkman, momentum and energy interphase terms is proposed. The dependence of the stream functions, isotherms and of the Nusselt numbers on the governing parameters is analysed.Design/methodology/approachThe both phases of flow and heat transfer are solved numerically using a modified finite difference technique. The algebraic system obtained after discretization is solved using the SOR method. The results are found to be in a significant agreement with the ones presented by the literature for a Darcy bidisperse porous medium and a Brinkman monodisperse porous medium.FindingsThe effects of the governing parameters on stream functions, isotherms and Nusselt numbers are discussed. It has been found that in the case of the Brinkman bidisperse model, the Nusselt numbers decrease compared to the Darcy model, and this behaviour is significant in comparison to the Brinkman monodisperse case.Originality/valueA mathematical model for the free convection inside a cavity filled by a non-Darcy bidisperse porous medium, based on the Brinkman equation, is used. The effect of Darcy number, Rayleigh number, modified inter-phase heat transfer parameter, modified thermal conductivity ratio and the inertial parameters is studied. To the best of the authors’ knowledge, this problem has not been studied before, and the results are new and original.

Computational models of effective thermal conductivity for periodic porous media for all volume fractions and conductivity ratios

The effective thermal conductivity (ETC) of composites is of great significance for simulating the macroscopic heat transfer process. In this paper, an extension of the morphology efficiency is proposed, which quantifies the influence of morphology on composite ETC, and is initially derived from two extreme models-series and parallel ETC bounds. The morphology efficiency obtained from different bound models are compared. It concluded that the morphology efficiency derived from Hashin and Shtrikman bound models is the best representative of the morphology of isotropic composite materials, which can conveniently reveal the optimal volume fraction of inclusion phase and thermal conductivity of the ideal thermal response. For composites with inverse Simple Cubic, Body Centered Cubic, Face-Centered Cubic and Kelvin lattice, the corresponding prediction model of ETC is proposed in a wide range of porosity and thermal conductivity. Among them, the ETC model of Kelvin cell and inverse Simple Cubic cell can well predict the high porosity foam and foams filled with phases with thermal conductivity ratio r in the range of 3 to 8, respectively.

Improved proton conductivity and mechanical performance of phosphoric acid doped aminated PAF-1 reinforced OPBI for high temperature proton exchange membranes

High-temperature proton exchange membranes (HT-PEMs) doped with phosphoric acid (PA) can achieve high proton conduction at high phosphoric acid doping level (ADL). However, polybenzimidazole (PBI) membranes have problems with PA loss, poor mechanical properties, and other issues at high ADL. Herein, PAF-1-NH2 was obtained through an amination of porous aromatic frameworks with an ultrahigh specific surface area (PAF-1), and APAF-1 was prepared by vacuum injection of PA on PAF-1-NH2 to increase the ADL through the high basic site amount and specific area. APAF-1/OPBI composite HT-PEMs was prepared by solution casting method. The composite membrane maintained superior mechanical properties, high proton conductivity and low dimensional swelling ratio (166.2%) even with a high PA doping rate (328.5%), due to the rigid structure of APAF-1 and the strong interfacial interaction between APAF-1 and OPBI. The mechanical strength and proton conductivity of the 10%APAF-1/OPBI were 20.86 MPa and 0.107 S cm−1 at 200 °C, respectively, which was about 2.43 times that of the OPBI membrane (0.044 S cm−1). When the catalyst Pt dosage was only 0.3 mg cm−2, the peak power density of the H2/O2 fuel cell at 180 °C was 366.6 mW cm−2. Therefore, this work presented a new approach for preparing HT-PEMs with excellent comprehensive properties.

The environmental assessment of soil chemical properties irrigated with treated wastewater under arid ecosystem of Al-Ahsa, Saudi Arabia

PurposeThe present study focused on examining the effect of treated wastewater (TWW) on soil chemical properties. Also, efforts were made to compare the soil chemical properties under TWW irrigation with that under groundwater (GW).Design/methodology/approachDuring the years 2021 and 2022, surface and subsurface soil samples were randomly collected in triplicate by using an auger fortnightly at two depths (20 and 40 cm) from the selected spot areas to represent the different types of irrigation water sources: TWW and GW. Samples of the GW and the TWW were collected for analysis.FindingsThis study examines the impact of TWW on soil characteristics and the surrounding environment. TWW use enhances soil organic matter, nutrient availability and salt redistribution, while reducing calcium carbonate accumulation in the topsoil. However, it negatively affects soil pH, electrical conductivity and sodium adsorption ratio, although remaining within acceptable limits. Generally, irrigating with TWW improves most soil chemical properties compared to GW.Originality/valueIn general, almost all of the soil’s chemical properties were improved by irrigating with TWW rather than GW. Following that, wastewater is used to irrigate the soil. Additionally, the application of gypsum to control the K/Na and Ca/Na ratios should be considered under long-term TWW and GW usage in this study area in order to control the salt accumulation as well as prevent soil conversion to saline-sodic soil in the future. However, more research is needed to thoroughly investigate the long-term effects of using TWW on soil properties as well as heavy metal accumulation in soil.

Study on Enhancing the Thermoelectric Stability of the β-Cu2Se Phase by Mn Doping.

Cu2Se is a promising thermoelectric (TE) material due to its low cost, Earth abundance, and high thermoelectric properties. However, the biggest problem of Cu2Se is its unstable chemical properties. In particular, under the action of an electric field or gradient temperature field, the chemical potential of copper ions inside the material increases. When the external field is strong enough, the chemical potential of copper ions at the negative end of the material reaches the chemical potential of elemental copper. Under these conditions, copper ions must precipitate out, causing Cu2Se to be unstable, and making it unsuitable for use in applications. In this study, we prepared Cu2-xMnxSe (x = 0, 0.02, 0.04 and 0.06) series bulk materials by vacuum melting-annealing and sintered by spark plasma sintering (SPS). We investigated the effects of Mn doping on the composition, microstructure, band structure, scattering mechanism, thermoelectric properties, and stability of Cu2Se. The results show that Mn doping can adjust the carrier concentration, promote the stabilization of the β-phase structure and improve the electrical properties of Cu2Se. When x = 0.06, the highest power factor (PF) value of Cu1.94Mn0.06Se at 873 K was 1.62 mW m-1 K-2. The results of carrier scattering mechanism analysis based on the conductivity ratio method show that the sample doped with Mn and pure Cu2Se had the characteristics of ionization impurity scattering, and the scattering factor was 3/2. However, the deterioration in thermal conductivity was large, and a superior zT value needs to be obtained. The cyclic test results of high-temperature thermoelectric properties show that Mn doping can hinder Cu+ migration and improve its thermoelectric stability, which preliminarily verifies the feasibility of using the stable zirconia mechanism to improve the thermoelectric stability of Cu2Se.

Topology optimization of natural convection using porous metal foam based on the adjoint lattice Boltzmann method and level set method

In this work, the level-set based topology optimization (TO) method for optimizing the distribution of porous metal foam in the fully-coupled natural convection system is developed. The respective adjoint lattice Boltzmann (LB) model and the sensitivity expression are derived. The forward LB model is validated by natural convection in cavity partially filled with porous medium and the TO method is validated by the pipe bend optimization problem. The validated TO method is utilized to design the two-dimensional passive heat sink made up of metal foam. It is found that the optimized design can approach the heat transfer enhancement of the conventional design with 100% filling while using only 40% material. For the base case, the average Nusselt number can be increased by 3.96∼6.74 times with the optimized designs mounted on the heating element when the Grashof number ranges from 15.7 to 2.8 × 104. Effects of increasing the Darcy number, decreasing the thermal conductivity ratio and decreasing the maximum foam volume fraction on the optimized designs and the heat transfer performance are discussed in detail. The two-dimensional TO structures are further stretched to three-dimension for further verification, and a 13.1%∼41.4% lower temperature than the conventional design is achieved by the optimized designs, indicating the superiority of the TO method.

Experimental study on the influence of electrical conductivity of hygroscopic compounds on the performance of a hygroscopic cycle

Dry climate conditions and the risk of desertification have increased significantly due to the effects of climate change. This fact, combined with the growing energy demand, leads to the need of research focused on improving the performance and efficiency of power plants. In the Hygroscopic Cycle Technology, recently implemented at industrial scale, steam condensation is performed in an absorber using solutions of hygroscopic compounds in water. Hygroscopic effects increase the condensing temperature for a given pressure, allowing the implementation of dry coolers at high ambient temperatures and eliminating cooling water consumption. In this work, due to their relevance in the cycle performance and control, the influence of the concentration of hygroscopic salts in the cycle has been studied, providing insight into proper operational ranges and key parameters. An experimental study of the influence of make-up water quality, with the concentration of impurities measured by water electrical conductivity and cycle mass flow ratio values has been performed in a pilot plant. The results, used to validate a mass and species conservation model, have allowed to obtain operational charts of the cycle and may help to reduce the amount of instrumentation required for cycle control. It was found that the decrease in electrical conductivities with boiler blowdowns in the cycle stabilized at a boiler blowdown ratio of 5%. Blowdown ratios above 10% did not result in substantially lower boiler Cycles Of Concentration in comparison with the increase of thermal energy losses and pumping power (0.42 kJ/kg for each additional 1% of blowdown). It was also found that the ratio between the cooling reflux and turbine steam conductivity had to be higher than 1.1 for condensation by absorption to occur, and that a minimum blowdown ratio of 0.04% was required to avoid using a droplet separator to control live steam quality. Hence, a compromise in the boiler blowdown ratio must be found for each particular application. Finally, hygroscopic effects in condensing pressure and temperature have been experimentally verified at pilot plant scale, leading to potentially higher cycle power output values and higher temperatures in the cooling stream of industrial power cycles, which may make it easier to reject heat from the cycle.

A versatile method for estimating grout and ground thermal properties in a thermal response test

Ground-Source Heat Pumps (GSHPs) are efficient means of space heating and cooling. However, owing to their high installation costs, their development in societies has not grown as it should. Therefore, it is crucial to have a meticulous design of these systems. The first step in designing GSHPs is determining the ground and grout thermal properties. Thermal Response Tests (TRTs) are developed for this purpose. The previous methods of estimating the unknown thermal properties are either inefficient or yield inaccurate estimates for the ground volumetric heat capacity, to which the mean fluid temperature has the slightest sensitivity among all thermal properties. Among previous methods, some facilitate estimating ground volumetric heat capacity by assuming a low ground-to-grout thermal conductivity ratio. This paper aims to estimate the thermal conductivities and volumetric heat capacities of ground and grout, assuming a higher ground-to-grout thermal conductivity ratio. A TRT, in which the ground-to-grout thermal conductivity ratio is 3.86, is simulated using a sufficiently accurate model, and thermophysical properties are identified utilizing a parameter estimation technique. A novel approach is adopted to estimate the ground volumetric heat capacity. The estimation technique identifies the remaining thermophysical properties iteratively by segregating the TRT duration into three intervals. The results indicate that the ground thermal conductivity and volumetric heat capacity are estimated with errors of 2.16% and 16.09%. The estimated grout thermal conductivity and volumetric heat capacity errors are 1.10% and 1.66%, respectively. In addition, the effect of fitting a smooth curve to the temperature readings was investigated. It was demonstrated that adding the pre-fitting step reduces the uncertainties of the estimated parameters.

Simulation of heat conduction in complex domains of multi-material composites using a meshless method

Several engineering applications involve complex materials with significant and discontinuous variations in thermophysical properties. These include materials for thermal storage, biological tissues, etc. For such applications, numerical simulations must exercise care in not smearing the interfaces by interpolating variables across the interfaces of subdomains. In this paper, we describe a high accuracy meshless method that uses domain decomposition and cloud-based interpolation of scattered data to solve heat conduction in such situations. The method is applicable to both steady state and transient problems. However, we have considered here only steady state heat conduction in complex domains. The polyharmonic spline (PHS) function with appended polynomial of prescribed degree is used for discretization. Flux balance condition must be satisfied at the interface points and the clouds of interpolation points are restricted to be within respective domains. Compared with previously proposed meshless algorithms with domain decomposition, the cloud-based interpolations are numerically better conditioned, and achieve high accuracy through the appended polynomial. The accuracy of the algorithm is demonstrated in several two and three dimensional problems using manufactured solutions with sharp discontinuity in thermal conductivity. Subsequently, we demonstrate the applicability of the algorithm to solve heat conduction in complex domains with practical boundary conditions and internal heat generation. Systematic computations with varying conductivity ratios, interpoint spacing and polynomial degree are performed to investigate the accuracy of the algorithm.

Activating and optimizing MoS2 basal-plane via spontaneous oxidation for enhanced photocatalytic hydrogen generation

MoS2 is a promising photocatalyst for hydrogen evolution reaction (HER), but its performance is still poor when used directly as a photocatalyst, due to its poor conductivity and high carrier recombination ratio. Here, through first-principles calculations, we find that spontaneous oxidation of the base plane can optimize the photocatalytic performance of MoS2. The MoS2−xOx crystal formed by spontaneous oxidation on the base plane results in an order of magnitude difference in electron-hole effective mass, and the electrostatic potential difference caused by symmetry breaking further promotes the effective separation of electron-hole pair, thus optimizing the photocarrier recombination rate of MoS2. In addition, with the increase of the degree of spontaneous oxidation, MoS2 bandgap continues to decrease, improving the intrinsic conductivity and visible light utilization. By comparing the REDOX potential of water splitting and the relative position of the band-edge in the neutral environment, the conduction band-edge of MoS2−xOx can meet the energy level requirements of photocatalytic HER until the doping concentration is 12.5%, and the high hydrogen production capacity has been reserved. Therefore, MoS2−xOx formed by spontaneous oxidation is an efficient and convenient photocatalyst with potential application prospect.

Conjugate local thermal nonequilibrium and non‐Darcy flow inside porous enclosure: Analysis of localized heating and cooling arrangements

AbstractThis study covers a simulation on conjugate free convective in a porous enclosure containing a side wall thickness and partially heated and cooled from sides under the considerations of local thermal nonequilibrium (LTNE) and non‐Darcy flow. Interest has been focused on how the side wall thickness and the locations of cooled and heated parts affect the effectiveness of the Nusselt number (Nu). Three different cases of localized heating and cooling locations have been implemented for the following ranges: scaled heat transfer coefficient (), wall to fluid thermal conductivity ratio (), modified Rayleigh number (), wall width (), inertial parameter (), and thermal conductivity ratio (). Outcomes show that and the locations of cooled and heated parts have remarkable impacts on all the Nusselt numbers. The intensity of LTNE region considerably relies on , and . The total average NuT is highly dependent on , , , , and as compared to H. The increase in leads to change of the convective mechanism to conductive mode. The rise in guides to increase Nu, where can control the flow strength. The actions of on Nuf is more evident than Nus. For low H and Kr, the size of LTNE zone is considerably affected by H as compared to Kr although Kr has a high influence on Nu. For high Kr and H, the LTNE zone has closely vanished. Findings display that the Case 2 provided the highest Nu for all tested parameters except the case of . Finally, it is evident that for the problems that employed solid conduction wall with localized heating and cooling sections, Case 2 is recommended for future use in the applications that implement a porous medium and depend on free convection.

Enhanced Ferroelectricity in Hf‐Based Ferroelectric Device with ZrO2 Regulating Layer

AbstractHfAlO film‐based ferroelectric memory is a strong contender for the next‐generation nonvolatile memories. However, the remanent polarization intensity of HfAlO films is small compared to other Hf‐based ferroelectric films at low annealing temperatures. In order to further improve the remnant polarization of the device, the ferroelectric memory with metal‐ferroelectric‐metal structure using ZrO2 as the regulating layer (RL) is designed and fabricated. Experimental results show that the device with the ZrO2 regulating layer exhibits triple enhancement, which may be due to the fact that ZrO2 RL has an effect on the enhancement of the ferroelectric phase. In addition, the device with ZrO2 regulating layer exhibits a superior ON/OFF conductance ratio, endurance, and retention characteristics, demonstrating potential for application to memory. This work provides an effective way to improve the ferroelectricity in HfAlO films at low annealing temperatures.

A review of 1D carbon-based materials assembly design for lightweight microwave absorption

The urgent needs of information security and the target stealth has led to an increasing demand for lightweight, high-performance electromagnetic wave absorbing materials. Recently, one-dimensional (1D) carbon-based materials based on their specific electrical conductivity and aspect ratios exhibits distinctive microstructural orientation, structural design, impedance matching, component modulation and surface modification. First, the high aspect ratio of the 1D dimensional material is much easier to construct effective conductive absorption networks. Second, the distinct voids in the networks built from 1D materials is facilitate to optimize the degree of impedance matching. In this paper, we review the recent research progress of 1D carbon-based microwave absorbing materials, including the types of 1D carbon-based composites, design strategies, synthesis methods, and the structure-function relationship of microwave absorbing materials. Finally, the challenges and prospects of 1D carbon-based materials for future applications are discussed. This critical review is timely and aims to provide researchers with a comprehensive understanding of the state-of-the-art in the design of 1D carbon-based material assemblies for lightweight microwave absorption, and to stimulate further innovation for ultralight carbon-based electromagnetic absorption material.

Effect of the Waveform of the Pulsed Electric Field on the Cylindrical Deformation of Uncharged Giant Unilamellar Vesicles.

High-speed imaging of giant unilamellar vesicles (GUVs) in recent years has shown significant shape deformation of these vesicles under electroporating direct current (DC) pulsed electric fields, possibly altering the surface distribution of transmembrane potential (TMP) and, thereby, the location and extent of electroporation on the bilayer membrane. The development of TMP, the corresponding shape deformation, and the extent of electroporation depend upon the waveform of the applied electric field. In this work, the deformation of vesicles was carried out under a high-intensity, single cycle of a sinusoidal pulsed electric field (SSPEF) and a square wave pulsed electric field (SWPEF). The cylindrical shape deformations of vesicles were observed for both SSPEF and SWPEF and were dependent upon the ratio of conductivity of the inner medium to the outer medium, α. For α = 1 and α > 1, the vesicles deformed into prolate cylinders as a result of Maxwell stress, whereas they were compressed into oblate cylinders for α < 1. Vesicles subjected to a SSPEF relaxed following either the pore closure dominated t2 or the efflux and lipid loss dominated, slow t3 mechanism depending upon the value of α. For α = 1 and α < 1, the relaxation of the vesicles was found to be predominantly dependent upon pore closure. On the other hand, a majority of vesicles gained excess area during poration when α > 1, which can be attributed to a higher TMP and faster charging of the membrane. The predictions of the approximate model for the deformation of vesicles agreed with the experiment, with deviations between the two as a result of the simplicity of the model. Moreover, the degree of deformation of vesicles [measured by the aspect ratio (AR)] and shape deformations of vesicles were found to be dependent upon the pulse width (TP) and amplitude (E0) of the SSPEF. The specific temporal variation of pore-forming tendencies of SSPEF and SWPEF, with their associated peculiarities, can be judiciously used for controlling electroporation in cells and vesicles.

The narrow band bap double perovskites X2CuInCl6 (X = K, Rb, Cs) for optoelectronics, and thermoelectric applications

The lead free, non-toxic, dynamically stable behavior of double perovskites make them promising materials for thermoelectric and optoelectronic applications. Therefore, the mechanical, optoelectronic, and transport characteristics of X2CuInCl6 (X = K, Rb, Cs) are addressed comprehensively by density functional theory. The phonon dispersion band structures are computed for dynamic stability, and tolerance factor for structural stability. The band structures show narrow band gaps (0.25, 0.42, 0.56) eV which are significantly important for infrared detectors and other optoelectronic devices operating with visible and IR light. The absorption peaks of maximum intensity are noted at 1.5 eV (827 nm), 2.0 eV (620 nm), and 2.5 eV (496 nm) for K, Rb, and Cs based DPs. Furthermore, thermoelectric behavior has been analyzed by the figure of merit, power factor, Seebeck coefficient, electrical to thermal conductivity ratio against chemical potential (−0.1 eV to 0.1 eV) and temperature (100–500 K). The ultralow values of lattice vibration, and large ZT increase their importance for thermoelectric generators.

Influence of variable viscosity and gravity fluctuation on double diffusive convection in a fluid layer with boundary slab of finite conductivity

The linear stability analysis is carried out for the onset of double-diffusive convection in a fluid layer with a boundary slab along with temperature-dependent viscosity and gravity fluctuation. The authors proposed three types of gravity fluctuation. We considered three cases of gravity field fluctuation: (a) linear and (b)parabolic and (c) cubic. An analytical solution for the subsequent problem is acquired through the perturbation technique. The findings demonstrate that the viscosity variation parameter, the thermal conductivity ratio, the gravity parameter, the depth ratio, and the soret parameter accelerate the start of convection, while the increasing Lewis number slow down the convective motion. Additionally, the system was found to be more stable for the linear type of gravity field fluctuation and more unstable for the cubic type of gravity field fluctuation.

Self-driven thermoelectric cooling contraption for liquid metals under the static magnetic field

The presence of large temperature gradients in liquid metals during heat transfer can also induce thermoelectric effects, which can lead to pumping or stirring of liquid metals under the action of magnetic fields. The thermoelectric effect of liquid metals has potential application background in both nuclear fusion and metal metallurgy. In this paper, an experimental study of flow driven by the Seebeck effect, in which the temperature-dependent voltage difference at an interface between dissimilar metals, in the presence of a magnetic field, can be used to create a Lorentz force. It is proposed that this method could be used for cooling electronics, fusion reactors, and solar technologies. The working fluid is eutectic gallium–indium–tin, and flow measurements are made with ultrasound. The flow velocity tends to increase and then decrease as the magnetic field increases. Two scaling relations are developed to predict the velocity, one for weak magnetic fields and one for strong magnetic fields. Those predictions are combined to estimate the maximum velocity. Temperature gradients and wall conductance ratio have a significant effect on the Seebeck effect self-driven flow. It is found that the self-driven flow velocity caused by the Seebeck effect is positively correlated with the number of channels in the multi-channel experiments. This design idea of self-generated flow and heat transfer of liquid metal in the magnetic field will provide the possibility of pumpless self-driven liquid lithium flow in nuclear fusion reactors and provide new ideas for cooling of electronic products and related energy-saving and emission reduction applications.