Joule Effect Research Articles

Rapid chloride penetration test: An evaluation of corrosion resistance in ultra-high performance concrete

Six Ultra-High Performance Concrete (UHPC) mixtures were tested to determine their chloride ion ingress potential using the rapid chloride penetration test (RCPT). The UHPC mixtures showed low to negligible chloride ion penetrability, depending on their water to cementitious materials (w/cm) ratio and curing regimen. Electrical resistivity and conductivity of the mixtures were determined based on the recorded electric current during the RCPT test. The electrical resistivity varied from 49 to 1419 Ω-meter, while conductivity ranged from 0.0007 to 0.0013 milli-Siemens/meter, indicating a moderate to very low expected corrosion rate for the mixtures. The chloride diffusion coefficient was calculated using the Nernst-Plank Equation, making corrections for Joule effect and temperature adjustment due to the temperature increase of the electrode solution during the RCPT test. The chloride ion diffusion coefficients of the UHPC mixtures ranged from 0.53–3.01 × 10−15 m2/s. These results suggest that UHPC mixtures with a w/cm ratio as high as 0.30 can exhibit excellent corrosion resistance.

Precision ratiometric technique for measuring the Peltier coefficient

We present a novel ratiometric approach to independently measure the Peltier coefficient, without using Kelvin’s relation, using the ratio of two temperature signals induced by the Peltier and Joule effects, in addition to readily obtained electrical quantities: electrical resistance and current. One major advantage is that the accuracy of the temperature measurement is not critical to the calculated Peltier coefficient, primarily because of the ratiometric measurement. Crucially, the thermophysical and geometrical properties of the sample are no longer part of the proposed measurement equation under optimal thermal and geometrical conditions. As a demonstration, the Peltier coefficient of a polycrystalline n-type Bi2Te3 sintered sample is measured. The use of an AC current with an amplitude equal to the DC current intensity precisely separates the Joule heating from Peltier heating. The obtained Peltier coefficient agrees well with that calculated from Kelvin’s relation within 3%. Compared with other approaches, the proposed approach requires only one additional AC measurement, which is an accurate and a comparably effortless undertaking. This study aims to significantly advance the development of highly accurate thermoelectric metrology.

Fabrication and characterization of copper and copper alloys reinforced with graphene

The consistent rise in current density within electrical wires leads to progressively more substantial heat losses attributed to the Joule effect. Consequently, mitigating the electrical resistivity of copper wires becomes imperative. To attain this objective, the development of a composite material that incorporates a more conductive reinforcement, like graphene, holds great promise. The conception of a copper/graphene composite using a powder metallurgy-based approach is presented. An optimum graphene quantity of 0.06 vol.% was obtained by calculation in order to limit the phenomenon of overlapping layers. This synthesis technique enables the dispersion of graphene and the meticulous control of the interface through the growth of CuO(Cu) nanoparticles that are tightly bonded to the reinforcement. The increase in the hardness of the various materials with separation of the graphene sheets by ultrasonic treatment (55.3 to 67.6 HV) was obtained. It is an indicator of the correct distribution of the reinforcement. The influence on the electrical properties of dendritic copper (ρe = 2.30 µΩ.cm) remains limited, resulting in a modest reduction in electrical resistance of around 1.4%. Nevertheless, for flake copper (2.71 µΩ.cm) and brass (7.66 µΩ.cm), we achieved a more substantial reduction of 2.7% and 10%, respectively. With the improvement of graphene quality, there exists a greater potential for further enhancing the electrical properties.

Multifunctional epoxy/carbon composites with a fully reparable interface

AbstractIn this work, for the first time, carbon fibers (CFs) were coated with nanosized‐polycaprolactone (PCL) particles to obtain a functionalized self‐healable interphase, capable to fully recover the pristine interfacial shear strength with a debonded epoxy matrix. PCL nanoparticles were initially water‐dispersed at different concentrations and deposited on CFs by electrophoretic deposition. The application of various voltage levels resulted in different morphologies of the coating. Epoxy microdroplets were deposited and cured on neat and PCL‐coated fibers. After complete interfacial debonding by microdebonding tests, an electric current was applied on CFs to activate a thermal interfacial healing by Joule effect. The healing efficiency was estimated as the ratio of interfacial shear strength measured before and after healing. An outstanding repairing efficiency was obtained upon thermal mending with a complete recovery of the original interfacial shear strength, thus indicating a strong potential of the PCL nanocoating as interfacial healing agent for composite structures.Highlights CFs were coated with nanosized‐PCL particles to obtain a functionalized self‐healable interphase. Electrophoretic deposition was employed for the fiber coating. Microdebonding tests were performed to assess the fiber/matrix interfacial properties in terms of interfacial shear strength. A full recovery of the interfacial properties was obtained via thermal interfacial healing by Joule effect.

Development of CNT-Based Nanocomposites with Ohmic Heating Capability towards Self-Healing Applications in Extrusion-Based 3D Printing Technologies

In the present study, a series of carbon-based nanocomposites based on recycled thermoplastic polyurethane (TPU) matrix and MWCNT fillers synthesized in a laboratory environment were prepared at various loadings and assessed in terms of their functional thermal, dielectric, and rheological properties, as well as their ohmic heating capability, for self-healing applications in extrusion-based 3D printing technologies. The synthesis of nanomaterials focused on the production of two different types of carbon nanotubes (CNTs) via the chemical vapor deposition (CVD) method. A comparative assessment and benchmarking were conducted with nanocomposite filaments obtained from commercial nanomaterials and masterbatches with MWCNTs. For all the polymer nanocomposites, samples were prepared at additive contents up to 15 wt.% and filament feedstock was produced via the melt-extrusion process for 3D printing; these were previously characterized by rheological tests. The measurements of thermal and electrical conductivity resulted in a selected composition with promising ohmic heating capability. As a preliminary assessment of the self-healing ability of the above samples, artificial cracks were introduced on the surface of the samples and SEM analysis took place at the crack location before and after applying voltage as a measure of the effectiveness of the material remelting due to the Joule effect. Results indicate a promising material response with a partial restoration of artificial cracks.

Modeling of functional fatigue of SMA-based actuators under thermomechanical loading and Joule heating

A new constitutive modeling is proposed to simulate the cyclic thermomechanical behavior of SMA-based actuators activated by Joule heating. It uses a weak coupling method to contemplate together the impact of different phenomena highlighted during experimental tests: thermal exchange through the SMA component and with the surrounding, heating by electric current (Joule effect), microstructural evolution leading to performance degradation (functional fatigue), and thermomechanical coupling. After experimental characterization and model implementation, simulation results are compared with experimental tests to validate the strategy and demonstrate its utility for designing SMA-based actuators.

Portable automatic detection system with infrared imaging for measuring steel wires corrosion damage

Accurate, cost-efficient and lightweight quantitative detection of steel wire corrosion in cable is an unsolvable issue that puzzles researchers and bridge owners. This paper proposed a portable automatic detection system for quantitative corrosion detection of replaced steel wires. The developed system consists of three parts (an automatic detection device, high-precision infrared imager, and corrosion evaluation algorithm). The proposed method is derived on the basis of Joule's law and the formula for calculating heat release. Then, the corroded specimens with different corrosion degrees and corresponding mass loss ratio were obtained by pre-corroded test to simulate industrial air corrosion and pickling test. The prior knowledge acquisition test utilizing presented automatic detection equipment was conducted to acquire the surface temperature of steel wires with various corrosion ratios by infrared camera after electric heating. Subsequently, the optimal quantitative corrosion prediction model after electric excitation is selected after infrared image processing, outlier filtering, theoretical method comparison, and model modification. Finally, the damaged steel wires from an in-service cable-stayed bridge are chosen to validate the proposed model's generalization ability and predictive accuracy. Furthermore, based on the discovery of characteristics on surface temperature of corroded steel wires after heating, the automatic detection device can be upgraded to realize the quantitative detection of in-situ corrosion of bridge cable.

A NUMERICAL STUDY OF JOULE HEATING EFFECT IN ELECTRODEPOSITION PROCESS-CASE OF COPPER ELECTRODEPOSITION

The electrochemical process in the presence of heat dissipation effect (Joule heating effect) is highly detected in practical electroplating solutions such as 0.6 M CuSO4+0.5 M H2SO4 electrolyte, where currents passing through the cathode-anode-electrolyte increase temperature in the electrolyte and electrodes. Due to the complex nature of such systems and the diversity of physics describing it, a theoretical approach of appearance for natural convection on vertical and horizontal sides of a cathode in the presence and absence of Joule effect under unsteady state condition was observed using Comsol Multiphysics. It was found that the onset of natural convection on a vertical side depends on the Joule effect, and the time (tn) for appearance is longer on the edges than in other areas. The horizontal side of a cathode assists the appearance of natural convection in the presence and absence of the Joule effect. The Rayleigh (Ra) number has larger values on the vertical side than the horizontal side due to the effect of surface concentration distribution Cs. A Sherwood, Sh-Ra mathematical relation such that Sh=0.03Ra0.86 was proposed where natural convection had no pronounced effect on the deposition process. It was found that the Joule heating effect negatively affects the electrodeposition process by reducing the local current values.

Novel Pre-treatment for Lignocellulosic Biomass Delignification Using Alkaline-Assisted Ohmic Heating

Lignocellulosic biomass (LCB) is a common substrate for biogas and bioethanol production due to its significant properties and abundance. However, it has a unique recalcitrant structure that can inhibit the production of biogas, which necessitates pre-treatment of the substrate to obtain higher cellulose or sugars ready for microbial hydrolysis in producing biogas. In this study, a novel approach for empty fruit bunch (EFB) pre-treatment has been made: ohmic heating pre-treatment. This method is conventionally used in the food industry for pasteurization and extraction. It involves electric current and resistance inside the material that releases heat (Joule effect). A preliminary study has been done to figure out the potential of alkaline assisted with ohmic heating (AA-OH) pre-treatment for EFB. Lignin reduction for AA-OH EFB is higher than EFB that undergoes only size reduction (SR) pre-treatment, which are 15.54% and 11.51%, respectively. After confirming the potential of ohmic heating as one of the pre-treatment methods for EFB, three parameters were investigated (reaction time, temperature, and solvent concentration) by one factor at a time (OFAT) testing to obtain the optimum condition for AA-OH pre-treatment. The optimal condition for achieving a high reduction in lignin (86.9%) and hemicellulose (75%) while also showing a significant increase in cellulose (63.2%), which is desirable for the fermentation process, is achieved by using 4% w/v of NaOH, ohmic-heated at a temperature of 120°C for 25 minutes. To sum up, this developed ohmic heating pre-treatment technique can be applied to LCB prior to biogas or bioethanol production.

Electro dynamic model of eddy currents in EU DEMO TF coil casing during major plasma disruption

The conceptual design of the EU DEMO reactor is currently ongoing within the EUROfusion consortium. Many different fault transients must be considered and carefully analyzed in the design phase; one of the most severe is the major plasma disruption (MPD), which causes several drawbacks on the magnet system. During a disruption, the plasma current decreases extremely fast, causing a fast variation of the magnetic field, which in turn induces an electric field. In presence of conductive materials, e.g., coil casing and vacuum vessel (VV), the electric field induces large eddy currents which deposit power by Joule effect. The conductive regions are tightly coupled on different timescales through the magnetic field induced by the eddy currents: the eddy currents in the VV influence the magnetic field evolution in the TF coil casing, thus affecting the power deposition in the latter. The aim of this work is the evaluation of the power deposited within the TF coil casing during a major plasma disruption due to eddy currents. The power deposition has been evaluated by means of the 3D-FOX, a finite element (FE) tool developed at Politecnico di Torino. The computed power deposition is used as input to the thermal-hydraulic (TH) simulation, performed with the 4C code, with the aim of assessing the erosion of the temperature margin given by MPD.

Thermal-hydraulic characterization of R513A during flow boiling inside a 6.0 mm horizontal tube, comparison with R134a and development of a new correlation

This paper presents two-phase heat transfer coefficient and pressure drop data of refrigerant R513A, a new azeotropic mixture conceived as possible alternative to R134a for medium temperature small-size refrigeration systems. All the experiments were performed in a commercial horizontal stainless-steel tube having an internal diameter of 6.0 mm and an outer diameter of 8.0 mm. The channel heating was obtained through DC current and Joule effect. The effect of the main operating parameters in terms of mass flux (from 150 to 500 kg/m2s), heat flux (from 5.0 to 40 kW/m2), saturation temperature (from 30 to 50 °C) and vapor quality (from the onset of boiling up to the dry-out occurrence) was analyzed and discussed for the heat transfer coefficient values, finding that both convective and nucleate boiling were significant contributions. The same ranges of mass flux and saturation temperature were also applied to frictional pressure gradient trends with vapor quality, taken in adiabatic conditions. The thermo-hydraulic performances were then compared with those of R134a, obtaining lower heat transfer coefficients and very similar pressure gradients. Finally, the collected experiments were assessed with values predicted from the most quoted correlations available in literature. A new composite method for nucleate-dominant or convective-dominant mechanisms was proposed for the evaluation of the heat transfer coefficient, with a mean absolute error of 25.3%, whereas the frictional pressure gradient values were well predicted with the Friedel correlation, that provides a mean absolute error of 13.8%.

Discrete Gagliardo–Nirenberg inequality and application to the finite volume approximation of a convection–diffusion equation with a Joule effect term

Abstract A discrete order-two Gagliardo–Nirenberg inequality is established for piecewise constant functions defined on a two-dimensional structured mesh composed of rectangular cells. As in the continuous framework, this discrete Gagliardo–Nirenberg inequality allows to control in particular the $L^4$ norm of the discrete gradient of the numerical solution by the $L^2$ norm of its discrete Hessian times its $L^\infty $ norm. This result is crucial for the convergence analysis of a finite volume method for the approximation of a convection–diffusion equation involving a Joule effect term on a uniform mesh in each direction. The convergence proof relies on compactness arguments and on a priori estimates under a smallness assumption on the data, which is essential also in the continuous framework.

Fiber Based Devices for Sensing and Actuating Applications

The importance of multifunctional smart medical devices increases constantly during the last decades, fuelled by socio - economic challenges such as population aging and high costs of the healthcare system. Consequently, numerous research teams are focused on developing such devices with multiple functionalities in terms of both diagnostic and therapeutical approaches.Wearables become ubiquitous since computing and communication devices got smaller and more powerful, new functions being constantly added to consumer products such as smart watches or fitness monitors. Physical or chemical parameters including pulse, blood pressure or oxygen saturation are easily measured. Employing complex architectures based on nanostructures and materials with tailored properties represents an important path in developing a new generation of wearable medical devices which may both monitor chemical parameters (sweat or blood composition) and deliver various therapies.The present report focuses on describing such architectures with the potential of incorporating both health monitoring, transdermal drug delivery and other therapeutic functions in a relatively straightforward manner. As functional elements microscopic fibers are employed as both electrodes for electrochemical sensors, as microscopic heaters for the drug delivery function or, as building blocks for other specific functions. The fibers are fabricated using electrospinning or centrifugal/force spinning and functionalization (e.g. electrical conductivity) is achieved through physical and electrochemical deposition. Therefore, the fibers can be covered with thin metal layers and rendered conductive, oxidic or polymeric layers making them responsive to various stimuli. Heating is achieved in a straightforward manner through Joule effect and the use of a temperature responding hydrogel enables a controlled release of specific drugs while simultaneously improving epidermal permeation.These fiber-based systems can be easily employed on cheap, biocompatible substrates such as paper or textile materials and therefore can be mass produced with reasonable costs leading to a new generation of medical devices with increased functionality.

Comparative Study of Two Nonlinear Control Strategies of Induction Motors considering Heating and Magnetic Saturation

Feedback linearization technique (FLT) linearizes the model of induction machine (IM). This actuator suffers from the variation of its inductances due to saturation and resistances due to joule and skin effects. Sliding-mode control (SMC) is widely recognized as a robust technique against parametric variations of IM. This control strategy has the advantage of being simple to implement and requires only a simple flux observer. This explains the use of FLT and SMC in this work to control an IM while taking into account the magnetic saturation and heating of the IM. Simulation results, conducted in a MATLAB/Simulink environment, demonstrate the relevance and efficiency of the proposed control schemes.

Experimental activities for the study of transformation of electrical energy into thermal

In this article, three experimental practices involving transformations of electrical energy into thermal energy using the Joule effect, electromagnetic induction, and the Peltier effect were proposed. Furthermore, energy balance calculations and the demonstration of the induction heating process are performed using a zero voltage switching module coupled to an Arduino board. In this sense, the work verifies the pedagogical potential of the activities applied in two classes of the third grade of high school, in the face-to-face class format. A qualitative research methodology was adopted, and for data collection, questionnaires were used to survey the students’ prior knowledge, which, at the end of the activities, were applied again to identify a possible integrating reconciliation on the content. We hope that with this proposal, we can contribute to other Physics teachers, who can replicate these activities with their students, adapting it to their realities.

Thermo-electro-mechanical microstructural interdependences in conductive thermoplastics

Additive manufacturing has enabled the design of thermoplastic components that provide structural support, electrical conductivity and heat generation modulated by mechanical deformation. The mechanisms and interplays that govern the material response at the microstructural level remain, however, elusive. Here, we develop an experimental method to characterise conductive filaments from a combined mechanical, electrical and thermal perspective. This approach is used to unravel exciting material interplays of conductive polylactic acid. To overcome experimental limitations that prevent a complete microstructural analysis of the problem, we develop a full-field homogenisation framework and implement it for finite elements. The framework accounts for viscoplasticity, electrical and thermal conduction, convection and heat generation via Joule effect, as well as for the interdependences between them. After experimental validation, the framework is applied to virtually optimise fabrication requirements to obtain desired properties in final products, i.e., stiffer products, filaments with higher conductivities or with better sensing capabilities.

Electrical Resistance Evolution of Graphite and Talc Geological Heterostructures under Progressive Metamorphism

The electrical properties of isolated graphene established precedents for studies of electrical superconducting materials at room temperature. After the discovery of stabilized graphene and graphite nanoplatelets in a geological context, the interest in characterizing the properties of these minerals arose. This work evaluates the electrical resistance evolution of mineral graphite and talc heterostructures under progressive metamorphism simulated in the laboratory. The experiments were conducted on an end-loaded piston-cylinder apparatus. This equipment allows for the application of equal pressure in all sample directions (lithostatic pressure) and heating, simulating geological phenomena. The behavior of two sets of mineral samples were compared: graphite and talc in billets and powder. Samples in billets were submitted to treatments at 400 °C and 4 kbar; 400 °C and 6 kbar; and 700 °C and 9 kbar. The powder samples were subjected to 700 °C and 9 kbar, with two ways of disposing the mineral powders (mixed and in adjacent contact) beyond 900 °C and 9 kbar (in adjacent contact). The results show that the samples in billets had lower electrical resistance when compared to the powder samples. The lowest electrical resistance was observed in the sample treated at 400 °C and 6 kbar, conditions that are consistent with metamorphic mineral assemblage observed in the field. Powdered samples showed better cleavage efficiency during the experiment, resulting in thinner flakes and even graphene, as pointed out by Raman spectroscopy. However, these flakes were not communicating, which resulted in high electrical resistance, due to the need for an electrical current to pass through the talc, resulting in a Joule effect. The maximum electrical resistance obtained in the experiment was obtained in the sample submitted to 900 °C, in which talc decomposed into other mineral phases that were even more electrically insulating. This work demonstrates that electrical resistance prospecting can be an efficient tool to identify potential target rocks with preserved mineral nanometric heterostructures that can form an important raw material for the nanotechnology industry.

Modeling and Simulation of a cooking inductors by Electromagnetic Induction

The fundamental concepts of induction heating have been discovered and applied to industrial processes since the 1920s. Its principle is based on the direct application of two physical laws, Lenz's law, and the Joule effect. The development of electromagnetic induction principles in cooking systems is progressing, as they offer better working conditions, good safety, high energy efficiency, and low pollution. Induction heating is the transmission of electromagnetic energy through the surface of a heated material via three physical phenomena: permeability, electrical conductivity and thermal conductivity, depending on temperature. This electro-thermal technique permits electrical conductive materials to be heated without physical contact with an electrical source. In particular, the study of the inductor position in the heating plate can improve and normalize the induction heating temperature. In this work, we proposed several geometries for cooking inductor position based on numerical modeling of induction heating processes using the finite element method on Matlab to solve all electromagnetic problems. The chosen geometrical model with 3 inductors has a good temperature distribution in the heating plate of about 650 K (377 C).

Experimental investigation of vibration control of flexible rotors using shape memory alloys

Vibration is an essential subject for the design of rotordynamic systems, being responsible for compromising the integrity and causing risks to operational functioning. This work deals with an experimental investigation of the semi-active vibration controller for a rotordynamic system using shape memory alloy (SMA) elements. SMAs are smart materials that present thermomechanical coupling represented by solid phase transformations that promote either stiffness change or hysteretic dissipation. In this regard, they are useful in controllers employing thermal actuation from electric current through the Joule effect. This paper presents a proof of concept of a controller using SMA elements. An experimental apparatus is proposed considering a typical rotor system using SMA wires at the bearings. In this regard, proper temperature variations allow the system to cross critical resonant conditions.

Optimisation of sample geometry for thermo‐mechanical testing of precipitation hardenable nickel‐based superalloys with an ETMT machine

AbstractAccurate determination of thermo‐mechanical properties in precipitation hardenable materials using an electro‐thermal mechanical testing (ETMT) system is a well‐established challenge. The non‐uniform distribution of temperature resulting from heating based on the joule effect (i.e., resistivity heating) leads to heterogeneous deformation along the gauge length, owing to the temperature dependency of mechanical properties, which makes their direct measurements complicated. This study presents an evaluation of four different miniaturised sample geometries that were tested to achieve an optimised sample with acceptable uniform strain and temperature distributions in the gauge volume. In‐situ displacement mapping, using digital image correlation (DIC), was utilised to calibrate the optimised sample dimensions with the aim of forcing the deformation to the hottest region of the gauge lengths during the tests. Tests were carried out on Inconel 718 (IN718) at 720°C, an optimal temperature for the precipitation of γ″, the primary strengthening particle in this alloy. The results showed that only in the case of the geometry proposed in this study (i.e., a sample with a short gauge length [~2 mm]) did the deformation acceptably localise at the centre, compared to other geometries. A correction methodology is developed that equates the strain measured using DIC over the 2 mm gauge length of the modified sample geometry with the strain measured using the linear variable differential transformer (LVDT) integrated to the ETMT, making future tests on IN718, and other precipitation hardenable materials, possible without the need for the use of a DIC system.