Diffusion-thermo Effects Research Articles

Analysis of fractionalized Brinkman flow in the presence of diffusion effect

A vertical plate experiences a dynamic flow of fractionalized Brinkman fluid governed by fluctuating magnetic forces. This study considers heat absorption and diffusion-thermo effects. The novelty of model is the fractionalized Fourier’s and Fick’s laws. The problem is solved using the constant proportional Caputo derivative and Laplace transform method. The resulting non-dimensional equations for temperature, mass, and velocity fields are solved and compared visually. We explore the influence of various parameters like the fractional order, heat absorption/generation (Q), chemical reaction rate (R), and magnetic field strength (M) through informative graphs. Additionally, we contrast the velocity fields of fractionalized and regular fluids. The visualizations reveal that diffusion-thermo and mass Grashof number enhance fluid velocity, while chemical reaction and magnetic field tend to suppress it. For the interest of engineering, physical quantities such as Sherwood number, skin friction, and Nusselt number are computed. The present study satisfying all initial and boundary condition can be reduced to to previous published work which shows the validity of present work.

Thermal Diffusion and Diffusion Thermo Effects on Axi-Symmetric Boundary Layer Flow of Nanofluid Due to Non-Linear Stretching Sheet along the Radial Direction in presence of Magnetic field

Thermal Diffusion and Diffusion Thermo Effects on Axi-Symmetric Boundary Layer Flow of Nanofluid Due to Non-Linear Stretching Sheet along the Radial Direction in presence of Magnetic field

Effect of slip on MHD flow of fluid with heat and mass transfer through a plate

Fractional order derivatives are recognized as advanced mathematical tools with broad applications in physics and engineering for deriving real-world solutions. This study examines a fractional order model of a non-linear Casson fluid, highlighting the widespread utility of fractional derivatives. Additionally, the problem incorporates the Dufour and slip effects. Specifically, the constant proportional Caputo fractional model is formulated using generalized Fick's and Fourier's laws. Initially, the governing equations are transformed into a non-dimensional form and subsequently solved using the Laplace transform. Analysis of the figures indicates that the Casson parameter reduces fluid motion, while the diffusion thermo effect enhances it. Furthermore, the study includes a comparison between fractionalized and ordinary velocity fields. Highlight: Introduction of novel CPC fractional derivative model of Casson fluid flow. Semi-analytically solutions using Laplace transform method for accurate fluid behavior representation. comprehensive parametric analysis linking theoretical findings. Temperature contour affected by significant values of Du?

Buongiorno’s radiative Prandtl-Eyring nanofluid flow through porous medium over a stretching surface with cross-diffusion effects

The main focus of the current analysis is to describe the thermo-magnetic flow, heat and mass transport features of two-dimensional dissipative Prandtl-Eyring nanofluid (PE-NF) flow over a stretching sheet under the influence of porous medium and magnetic Ohmic dissipation numerically. An innovative Buongiorno’s nanofluid model in terms of Brownian motion and thermophoresis is deployed to accurately simulate the nano behavior in Prandtl-Eyring within the boundary layer regime. The thermal radiation and heat source/sink effects are also included to describe the thermal transport process. In addition to this, the thermo-diffusion and diffusion-thermo effect are included to demonstrate the temperature and concentration diffusion mechanism under the presence of chemical reaction process. The emerged coupled nonlinear two-dimensional time-independent partial differential equations are rendered to their dimensionless form through appropriate similarity transformations and solved by deploying Matlab-based BVP4C technique. The graphical visualization showed that, the increasing magnetic number diminished the flow field and enhanced the temperature and concentration profiles in the flow regime. Rising porous parameter decayed the Prandtl-Eyring nanofluid velocity. Increasing radiation and Eckert numbers enhance the temperature field in the flow regime. Magnifying Prandtl-Eyring parameter suppressed the velocity diffusion. Increasing Brownian motion and thermophoresis parameters increases the temperature profile. Amplifying Soret parameter upsurges the concentration profile. Skin-friction coefficient amplified with enhanced magnetic and porous numbers. Heat transfer rate acts as increasing function of thermophoresis and Brownian motion parameters. The main objective of this study is the addition of magnetic Ohmic dissipation, radiation, porous medium, thermal source/sink, Soret and Dufour effects and Buongiorno nanofluid model and this consideration generalizes former studies and gives a new re-defined mathematical formulation of heat and mass transport features of Prandtl-Eyring nanofluid flow over a stretching sheet. Finally, the numerical accuracy of the current similarity results is validated with available solutions and noticed a good agreement.

3D-MHD mixed convection in a darcy-forchheimer maxwell fluid: Thermo diffusion, diffusion-thermo effects, and activation energy influence

In this article, the three-dimensional upper-convected Darcy-Forchheimer Maxwell (UCM) nanofluid flow over a stretching surface is analyzed to investigate the effects of activation energy, thermodiffusion, diffusion thermo, and magnetohydrodynamics (MHD) on heat and mass transfer. The energy equation incorporates a nonlinear radiative heat flux. Using similarity transformation, the nonlinear partial differential equations are reduced to ordinary differential equations, which are then solved using the well-known shooting technique via the fourth-order Runge-Kutta integration method. To validate our results, we also employ MATLAB's built-in function bvp4c. The impact of various parameters, such as activation energy, diffusion thermo, thermodiffusion, Brownian motion parameter, Prandtl number, thermophoresis parameter, and magnetic parameter, on velocity, temperature, and concentration is discussed both graphically and numerically. It is observed that the flow velocity decreases with an increasing magnetic field parameter. Additionally, higher values of the activation energy parameter reduce the nanoparticle concentration profile. The temperature and concentration exhibit opposite behaviors when thermodiffusion and diffusion thermo effects are enhanced.

Directionality of gravitational and thermal diffusive transport in geologic fluid storage.

Diffusive transport has implications for the long-term status of underground storage of hydrogen (H_{2}) fuel and carbon dioxide (CO_{2}), technologies which are being pursued to mitigate climate change and advance the energy transition. Once injected underground, CO_{2} and H_{2} will exist in multiphase fluid-water-rock systems. The partially soluble injected fluids can flow through the porous rock in a connected plume, become disconnected and trapped as ganglia surrounded by groundwater within the storage rock pore space, and also dissolve and migrate through the aqueous phase once dissolved. Recent analyses have focused on the concentration gradients induced by differing capillary pressure between fluid ganglia which can drive diffusive transport ("Ostwald ripening"). However, studies have neglected or excessively simplified important factors, namely the nonideality of gases under geologic conditions, the opposing equilibrium state of dissolved CO_{2} and H_{2} driven by the partial molar density of dissolved solutes, and entropic and thermodiffusive effects resulting from geothermal gradients. We conduct an analysis from thermodynamic first principles and use this to provide numerical estimates for CO_{2} and H_{2} at conditions relevant to underground storage reservoirs. We show that while diffusive transport in isothermal systems is upwards for both gases, as indicated by previous analysis, entropic contributions to the free energy are so significant as to cause a reversal in the direction of diffusive transport in systems with geothermal gradients. For CO_{2}, even geothermal gradients less than 10^{∘}C/km (far less than typical gradients of 25^{∘}C/km) are sufficient to induce downwards diffusion at depths relevant to storage. Diffusive transport of H_{2} is less affected but still reverses direction under typical gradients, e.g., 30^{∘}C/km, at a depth of 1000m. This reversal occurs independent of the solute's thermophobicity or thermophilicity in aqueous solutions. The entropic contribution also modifies the magnitude of flux where geothermal gradients are present, with the largest diffusive fluxes estimated for CO_{2} with a 30^{∘}C/km gradient, despite the higher diffusion coefficient of H_{2}. We find a maximum flux on the order of 10^{-13} mol/(cm^{2}s) for CO_{2} in the 30^{∘}C/km scenario; significantly lower than literature estimates for maximum convective fluxes in moderate to high permeability formations. Contrary to previous studies, we find that in diffusion and convection will likely work in concert-both driving CO_{2} downwards, and both driving H_{2} upwards-for conditions representative of their respective storage reservoirs.

Heat and Mass Transformation of Casson Hybrid Nanofluid (MoS2 + ZnO) Based on Engine Oil over a Stretched Wall with Chemical Reaction and Thermo-Diffusion Effect

This study investigates the potential of a hybrid nanofluid composed of MoS2 and ZnO nanoparticles dispersed in engine oil, aiming to enhance the properties of a lubricant’s chemical reaction with the Soret effect on a stretching sheet under the influence of an applied magnetic field. With the growing demand for efficient lubrication systems in various industrial applications, including automotive engines, the development of novel nanofluid-based lubricants presents a promising avenue for improving engine performance and longevity. However, the synergistic effects of hybrid nanoparticles in engine oil remain relatively unexplored. The present research addresses this gap by examining the thermal conductivity, viscosity, and wear resistance of the hybrid nanofluid, shedding light on its potential as an advanced lubrication solution. Overall, the objectives of studying the hybrid nanolubricant MoS2 + ZnO with engine oil aim to advance the development of more efficient and durable lubrication solutions for automotive engines, contributing to improved reliability, fuel efficiency, and environmental sustainability. In the present study, the heat and mass transformation of a Casson hybrid nanofluid (MoS2 + ZnO) based on engine oil over a stretched wall with chemical reaction and thermo-diffusion effect is analyzed. The governing nonlinear partial differential equations are simplified as ordinary differential equations (ODEs) by utilizing the relevant similarity variables. The MATLAB Bvp4c technique is used to solve the obtained linear ODE equations. The results are presented through graphs and tables for various parameters, namely, M, Q, β, Pr, Ec, Sc, Sr, Kp, Kr, and ϕ2* (hybrid nanolubricant parameters) and various state variables. A comparative survey of all the graphs is presented for the nanofluid (MoS2/engine oil) and the hybrid nanofluid (MoS2 + ZnO/engine oil). The results reveal that the velocity profile diminished against the values of M, Kp, and β, and the temperature profile rises with Ec and Q, whereas Pr decreases. The concentration profile is incremented (decremented) with the value of Sr (Sc and Kr). A comparison of the nanofluid and hybrid nanofluid suggests that the velocity f′ (η) becomes slower with the augmentation of ϕ2* whereas the temperature increases when ϕ2* = 0.6 become slower.

Computational analysis of transient thermal diffusion and propagation of chemically reactive magneto-nanofluid, Brinkman-type flow past an oscillating absorbent plate

The current work concentrates on increasing the thermal and solutal performance in exponentially accelerating vertical surfaces via the utilization of nanofluids containing the mixtures of base water fluid and Aluminum oxide (Al2O3), Copper (Cu), Titanium dioxide (TiO2) and Silver (Ag) nanoparticles. During the fully utilize the capabilities of nanoparticles in a variety of applications and to evaluate the effects that they will have on the environment and biological systems, it is crucial to comprehend and manage heat transmission. This motivation allows us to investigate the nanofluid boundary layer flows under cross-diffusion effects, as this model study earlier was not conducted, thus the results of this work are new, which describe the novelty of the current problem. The partial differential equations for the developed model are altered into dimensionless statements first via non-dimensionalization. The numerical simulations implementing a finite difference scheme are applied for the solution description. The physical description of the variation of momentum, temperature, and mass fields for different factors is computed and presented graphically for ramped temperature and isothermal heat cases. Convergence and validation of the problem are checked with the help of tables. We found that enhancement in the Reynolds number, Brinkman parameter and magnetic field mark a downward trend in the fluid velocity, but it strengthens with the porosity parameter and time factor. The temperature distribution expands for advancing diffusion-thermal and radiation effects, whereas a contrary pattern was noted with the Prandtl number and heat consumption parameter. The thermo-diffusion effect enlarges the concentration distribution but decays with chemical reaction and Schmidt number.

Impact of variable electrical conductivity, viscosity on convective heat and mass transfer flow of CuO- and Al2O3-water nanofluids in cylindrical annulus

In the food industry, electrical conductivity is essential for heating processes. The dependence on temperature conductivity of electricity on the outermost layers flow of the nanofluid is the main topic of this paper. Variable electrical conductivity, viscosity, thermo diffusion, thermal radiation and radiation absorption on convective heat and mass transfer flow Cuo and Al2O3-water nano-fluids confined in cylindrical annulus. The non-linear governing equations have been solved by finite element technique with quadratic approximation functions. For various parametric adjustments, the temperature, speed, and nanoconcentration have all been examined. Similar to the cylindrical wall, quantitative evaluations have been made of the surface resistance, temperature rate and mass transport. It is discovered that for both types of nanofluids, a higher thermo-diffusion effect leads to a lower concentration and Sherwood digits on the cylinders. An augment in Q1 enriches the rapidity in CuO-water nanofluidic system as well as decreases in Al2O3-water nanofluidic. Increased Q1 lowers the real temperature and nanoconcentration in both types of nanofluids.

Effect of thermodiffusion on compositional grading in hydrocarbon reservoirs: Insights from field cases and simulations

Heterogeneity of fluid composition in vertical and lateral directions is observed in many reservoirs, known as compositional grading. It is necessary to evaluate the diffusion forces for modeling this phenomenon. In addition to the chemical and gravity forces, the temperature gradient causes mass diffusion. In the present investigation, the accuracy and reliability of the Haase theory and the Shukla-Firoozabadi method in thermodiffusion modeling are studied comprehensively using field samples from light to heavy-oil reservoirs. On the one hand, the Shukla-Firoozabadi model results in compositional grading reduction by thermodiffusion; on the other hand, the Haase theory reveals enhancement and attenuation effects of thermodiffusion depending on reference enthalpy quantification. A new approach, which employs the reference enthalpies of pseudocomponents as tuning parameters, is proposed to improve the results of the Haase theory. The proposed procedure is also validated using field cases. In addition, the experimental field information compared with isothermal and nonisothermal models are studied to answer the question of "how" and to "what extent" thermodiffusion contributes to compositional grading. Results demonstrated the limited attenuation effect of thermodiffusion in light oils, while this phenomenon leads to severe enhancement of compositional grading in the medium and heavy-oil reservoirs. In heavy oils, the thermodiffusion effect is more pronounced on heavy pseudocomponents rather than light paraffinic species. Finally, the practice of compositional gradient model optimization, which is of particular interest to reduce the uncertainty in fluid initialization and to address reservoir compartmentalization, is presented.

Insight into the bidirectional dynamics of hyperbolic tangent hybrid nanomaterial subject to Nield’s conditions using numerical approach

A hyperbolic tangent fluid model characterized by shear rate dependent viscosity together with the effects of hybrid nanoparticles, Brownian motion, thermo-diffusion, and Nield’s conditions, is utilized for thermal enhancement purpose. Five percent copper nanoparticles and twenty percent alumina nanoparticles are submerged into ethylene glycol with the parametric influence of tangent hyperbolic fluid to obtain the tangent hyperbolic hybrid nano suspension. Numerical solutions of the nondimensionalized conservation laws are found by the Keller-box method. The influence of various parametric factors on velocity, temperature, concentration, Nusselt number, and Sherwood number has been discussed. A constant Nusselt number is noted with the influence of Nield’s constraints. A 90% increase in thermal conductivity is achieved by dispersing 5% copper and 20% alumina nanoparticles into the ethylene glycol with the influence of hyperbolic tangent fluid. The error and convergence analysis of the numerical solution have been discussed, along with the validation of the obtained numerical results.

Achieving Ultrahigh Voltage Over 100 V and Remarkable Freshwater Harvesting Based on Thermodiffusion Enhanced Hydrovoltaic Generator

AbstractEvaporative hydrovoltaic generators hold significant potential for alleviating water‐energy crisis, but low output voltage configurations due to the slow phase transition rate of water molecules and the intricate nature of integration limit their applications. Herein, a lotus‐inspired interfacial evaporation‐driven hydrovoltaic generators (IEHVG) is developed for efficient generation of water vapor and electricity from seawater instead of freshwater and achieves an ultrahigh voltage output higher than 100‐volt level through forested IEHVG integration. The biomimetic hydrogel is developed with specific liquid transport channels, graphene quantum dots/MXene nanocomposites, and gradient hydrophobic interface for highly enhanced photothermal evaporation and electricity generation by mimicking the transpiration process of a “stems‐leaves of lotus”. The synergistic thermodiffusion effect leads to the output power density of IEHVG reaches up to 45.6 µW cm−2 and can power electronic devices or charge commercial supercapacitors. The freshwater‐electricity cogeneration integrated system consisting of 192 IEHVG units can harvest a record‐breaking voltage reaching 105 V and a high freshwater harvesting rate up to 2.0 L m−2 h−1 from seawater in a well‐lit outdoor area. This work demonstrates that IEHVG offers a novel concept for modular freshwater and high‐voltage power sources access on offshore work platforms.

Development and validation of a phenomenological model for hydrogen fueled PFI internal combustion engines considering Thermo-Diffusive effects on flame speed propagation

This paper proposes a 1D numerical/experimental study on a single-cylinder research ICE equipped with a hydrogen Port Fuel Injection (PFI) system. The experimental campaign covered tests at the fixed speed of 1500 rpm and different levels of load, from 5 bar to 11 bar IMEP, and of air excess, with a relative air-to-fuel ratio ranging from 1.4 to 4.0. A 0D/1D model of the investigated ICE is developed, including detailed combustion, turbulence, and NOx emission sub-models. In particular, combustion model is based on the fractal approach, k-K-T model is adopted for describing turbulent phenomena and NOx emissions are predicted by the Zeldovich mechanism. A sub-model was developed to assess the influence of Thermo-Diffusive (TD) instabilities on the freely propagating flame speed accounting for equivalence ratio, variable transport coefficients and reaction orders. This evaluation considered the impact of TD instabilities commonly observed in lean premixed hydrogen combustion on the flame front. The engine model calibration process enabled the comparison between numerical predictions and experimental observations, encompassing pressure cycles, burn rate traces, and main engine performance (air flow rate, IMEP, indicated efficiency, and timing of main combustion events). The model replicated the IMEP with an average error of 2.5%, gross indicated efficiency with an average error of 1.6%, main combustion angles with an average error of 3.8 CAD on CA50, and NOx emissions satisfactorily, showing high sensitivity to operational parameters. Nonetheless, less accurate predictions occur in cases with significantly elevated λ values (λ>3.6), which were attributed to the presence of thickened flames, where some assumptions inherent to the adopted combustion model may fail. Finally, a comparison between the proposed approach and the one proposed in Ballerini et al. (2022) is presented, and readers are provided with recommendations for further development of future models that account for Thermo-Diffusive instabilities in lean hydrogen combustion.

Effects of Diffusion Thermo and Thermal Diffusion on an Unsteady MHD Dissipative Squeezing Flow of Casson Fluid Over Horizontal Channel in the Presence of Radiation and Chemical Reaction

This study analyses the impacts of Diffusion thermo and thermal diffusion on the magneto hydrodynamic (MHD) squeezing Casson fluid flow through a porous medium under the slip condition with viscous dissipation the presence of chemical reaction and thermal radiation. The flow is produced when two plates are compressed together in close proximity to one another. Using similarity variables may successfully convert partial differential equations (PDEs) to ordinary differential equations (ODEs). The shooting technique was used to perform the numerical analysis, which entailed solving the competent governing equations with dominating parameters for a thin liquid layer. This was done to determine the results of the study. It is essential to evaluate the numerical results in light of previously conducted research to validate the current answers. According to the results, an increase in the distance between the two plates leads to a rise in the velocity and the wall shear stress. The velocity diminishes due to an increase in the Hartmann and Casson parameters, whereas the reverse behaviour has been observed in the case of temperature and concentration. The opposite behaviour has been observed in temperature with increasing Diffusion thermo and thermal diffusion parameters.

Elasto‐thermodiffusive interaction under void due to nonlocal stress theory

AbstractThe current investigation address a novel generalized elasto‐thermodiffusion model for a thermoelastic porous half‐space incorporating the nonlocal stress theory proposed by Eringen. Modeling of the problem is performed by adopting Moore‐Gibson‐Thompson (MGT) thermoelasticity theory defined in an integral form of a common derivative on a slipping interval, well known as the memory‐dependent derivative. The bounding plane of the medium is subjected to time‐dependent thermal and chemical shocks and there is no change in the volume fraction field. Laplace transform and the Fourier transform techniques have been adopted to represent the analytical solutions in the transformed domain. The distributions of the physical fields such as the temperature, stress, chemical potential, mass concentration and the volume fraction field were found in the real space‐time domain adopting suitable numerical scheme based on the Fourier series expansion. According to the discussion of the computational results and the respective graphical representations, the prominent role of different parameters such as the effect of nonlocality, effect of void and thermodiffusion is analyzed. Moreover, the superiority of a nonlinear kernel function compared to a linear form is also reported.

MHD peristaltic two-phase Williamson fluid flow, heat and mass transfer through a ureteral tube with microliths: Electromagnetic therapy simulation

The ureter typically experiences a frequency of one to five peristaltic contractions per minute. However, it is important to note that these contractions can be disrupted by various physical and mechanical irritants. Ionic contents in the urine make it electrically conducting and responsive to electromagnetic body forces. MHD can be deployed in bio magnetic therapy to control or mitigate symptoms associated with peristaltic pumping in the urinary system. This article therefore focuses on the hydromagnetic effects on flow patterns of urine with debris (monoliths). The mechanism of urine flow is largely coordinated by the kidneys. The flow inside the ureter is interrupted by microliths, which are generated by the sedimentation of excretory products. To simulate this, a two-phase formulation is adopted, comprising the electromagnetic urological viscous fluid phase and the particulate phase for solid grains. The peristaltic propulsion of two-phase liquid in the ureter is simulated as a sinusoidal wave propagation of incompressible non-Newtonian fluid. The Williamson viscoelastic model is deployed for the rheology. Heat transfer is also included with Soret thermo-diffusion and viscous heating effects. Long wave and low Reynolds number approximations are employed based on lubrication theory. The mass, momentum, energy and concentration conservation equations with associated boundary conditions are rendered non-dimensional via appropriate scaling transformations. A numerical solution is achieved via BVP4C MATLAB quadrature. Graphical visualizations of the velocity, temperature and concentration (solid grains) are given for the influence of suspension parameter ( ζ ), Hartmann number (M), Prandtl number (Pr), Weissenburg number (We), particle volume fraction (C), Eckert number (Ec), Soret number (Sr), Schmidt number (Sc). The novelty of the present work is therefore the simultaneous consideration of a generalized two-phase model, wall slip, non-Newtonian characteristics, cross diffusion, viscous dissipation, mass diffusion, magnetic body force and curvature effects in peristaltic urological transport, which has not been undertaken previously. The detailed simulations reveal that the flow velocity is reduced due to the presence of solid particles and the channel curvature, in comparison to the flow in an unobstructed channel devoid of solid particles. Enhancing the hydrodynamic slip parameter speeds up the movement of particles and fluid near the channel walls, boosts wall skin friction, raises pressure difference in the pumping area, and amplifies bolus magnitudes.The rise in peristaltic pumping results in a reduction in solid particle concentration, which is significant phenomena.This theoretical approach may aid in treating conditions such as Urinary Tract Infections (UTIs). The computations effectively demonstrate that significant manipulation of urological pumping characteristics can be achieved with an electromagnetic field. Some new features of two-phase ureteral dynamics are highlighted as relevant to magnetic therapy techniques, which may be beneficial to clinicians.

Irreversibility estimation of MHD thermosolutal convection of Powell–Eyring fluid flow through an inclined microchannel

ABSTRACT Due to the impressive utility of the mass transport phenomena on microscales for various miniaturised devices, the theoretical and experimental studies in microchannel flows to analyse heat and mass transport find enormous interest in researchers. Investigations in microchannel flows have gigantic applications in biochips, drug delivery, and cooling of microchips. This article examines the combined heat and mass transport of Powell–Eyring fluid through a permeable inclined microchannel considering magnetism, thermo-diffusion, and Navier's slip effects under convective boundary conditions. To solve the nonlinear system numerically MATLAB bvp4c solver is employed. This analysis reveals that the entropy generation due to thermosolutal irreversibility is enhanced strictly with the thermo-diffusion effect and solutal Biot number. The Bejan number profile shows a dominating character of Reynold's number close to the upper channel wall and deteriorates with the immense solutal Grashoff number. Also, it achieves maximum and minimum values for the supreme thermal Biot number and Eckert number, respectively in the middle of the channel. The outcome of the study may provide significant insight into controlling flows through microchannels as well as manipulating microfluidic and biomedical devices for minimising energy loss and designing an efficient model for better thermal performance and transmission of chemical species.

Zinc-iodine thermal charging cell engineered by cost-efficient electrolytes for low-grade heat harvesting

Emerging ionic thermoelectric devices (i-TEs), with synergistic effect of thermogalvanic effect and thermo-diffusion effect, are promising devices to achieve heat to electricity. We report a zinc-iodine thermal charging cell (ZITCC) enabled by cost-efficient electrolytes for low-grade heat harvesting. Efficient functional electrolytes are obtained through optimization from Zn(NO3)2, Zn(CH3COO)2 and ZnSO4 electrolytes and introducing redox species (I−/I3−). The ZITCCs generate electricity through thermo-diffusion effect of electrolyte ions, as well as the thermogalvanic effect involving I− to I3− conversion and Zn plating, enabling efficient heat-to-electricity conversion. The Seebeck coefficient of 19.2 mV K−1, a high output voltage of ∼1 V and superior normalized maximum power density of 0.44 mW m−2 K−2 is obtained at temperature difference of 15 K. Meanwhile, ZITCCs have good energy storage capacity. In addition, a quasi-solid-state device delivers an 8.5 mW m−2 output power and impressive performance at temperature difference of 8 K can be acquired. This work provides a good strategy for the design of high-Seebeck coefficient, cost-effective i-TEs for low-grade heat harvesting.

A double network facilitated ion-electron conductor for thermoelectric harvesting with high energy density

As a young member of the thermoelectric (TE) family, ionic thermoelectric (i-TE) technology stands out due to its exceptionally high thermopower. However, the intermittent nature of its heat utilization results in a weak power output, thus limiting its practical application. To tackle this issue, combining i-TE with electronic thermoelectric (e-TE) materials that exhibit stable heat-to-electricity conversion capabilities presents itself as a promising solution. With this aim, we introduced interpenetrating network (IPN) structure in the fabrication process of mixed ionic-electronic TE (MIETE) materials. Specifically, we created a double network MIETE converter through the in-situ polymerization of ionic poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) on a loosely structured poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/lithium bis(trifluoromethane)sulfonimide (LiTFSI) electronic conductive framework. This subsequent construction of the inert network ensures uninterrupted electronic conductivity and boosts density for improved conductivity (σ). The innovative structural design effectively amalgamates thermodiffusion and Seebeck effects, facilitating continuous electricity generation. The resulting hybrid PEDOT:PSS/LiTFSI/PAMPS-LiCl (PLiP) hydrogels exhibit exceptional TE performance, showing a thermopower of 7.86 mV K−1 and σ of 33.3 mS cm−1. It is worth noting that the PLiP hydrogel illustrates a power generation time of over 4 h and an ultra-high energy density of 93.7 J m−2, which exceeds other TE hydrogels based on the thermodiffusion principle.

The role of thermodiffusion in transpiration.

Plant leaf temperatures can differ from ambient air temperatures. A temperature gradient in a gas mixture gives rise to a phenomenon known as thermodiffusion, which operates in addition to ordinary diffusion. Whilst transpiration is generally understood to be driven solely by the ordinary diffusion of water vapour along a concentration gradient, we consider the implications of thermodiffusion for transpiration. We develop a new modelling framework that introduces the effects of thermodiffusion on the transpiration rate, E. By applying this framework, we quantify the proportion of E attributable to thermodiffusion for a set of physiological and environmental conditions, varied over a wide range. Thermodiffusion is found to be most significant (in some cases > 30% of E) when a leaf-to-air temperature difference coincides with a relatively small water vapour concentration difference across the boundary layer; a boundary layer conductance that is large as compared to the stomatal conductance; or a relatively low transpiration rate. Thermodiffusion also alters the conditions required for the onset of reverse transpiration, and the rate at which this water vapour uptake occurs.