Heat Generation Research Articles

Singular dielectricnanolaser with atomic-scale field localization.

Compressing the optical field to the atomic scale opens up possibilities for directly observing individual molecules, offering innovative imaging and research tools for both physical and life sciences. However, the diffraction limit imposes a fundamental constraint on how much the optical field can be compressed, based on the achievable photon momentum1,2. In contrast to dielectric structures, plasmonics offer superior field confinement by coupling the light field with the oscillations of free electrons in metals3-6. Nevertheless, plasmonics suffer from inherent ohmic loss, leading to heat generation, increased power consumption and limitations on the coherence time of plasmonic devices7,8. Here we propose and demonstrate singular dielectric nanolasers showing a mode volume that breaks the optical diffraction limit. Derived from Maxwell's equations, we discover that the electric-field singularity sustained in a dielectric bowtie nanoantenna originates from divergence of momentum. The singular dielectric nanolaser is constructed by integrating a dielectric bowtie nanoantenna into the centre of a twisted lattice nanocavity. The synergistic integration surpasses the diffraction limit, enabling the singular dielectricnanolaser to achieve an ultrasmall mode volume of about 0.0005 λ3 (λ, free-space wavelength), along with an exceptionally small feature size at the 1-nanometre scale. To fabricate the required dielectric bowtie nanoantenna with a single-nanometre gap, we develop a two-step process involving etching and atomic deposition. Our research showcases the ability to achieve atomic-scale field localization in laser devices, paving the way for ultra-precise measurements, super-resolution imaging, ultra-efficient computing and communication, and the exploration of light-matter interactions within the realm of extreme optical field localization.

Analytical Solution for Transient Thermal Behavior of Two Semisolids With Contact Resistance and Interfacial Heat Generation

Abstract The problem of two dissimilar semi-infinite solids at different initial temperatures brought into contact has a well-known simple analytical solution. In this work, this problem is reexamined with the additional simultaneous complications of both contact resistance and surface heat generation. While contact resistance is always present to some degree due to surface asperities or oxidation layers, heat generation at the contact interface can also occur in certain situations. These situations can occur in applications such as ultrasonic welding or arise in situations involving electromagnetic radiation passing through an optically transparent medium, but dissipating as heat at an interface with an opaque material that is in contact with the transparent material. In this paper, an analytical solution to the unsteady conduction problem is developed that accounts for both contact resistance and interfacial heat generation. The solution confirms that the initially warmer object rapidly decreases in temperature in the vicinity of the interface as heat flows into the cooler object and the heat generated at the interface preferentially flows to the cooler material. After a short time, however, the temperatures of both materials at the interface increase in temperature above even the initial temperature of the initially hotter material. An experiment was performed that verified the analytical solution.

Experimental and Mathematical Investigation of Thermochemical Conversion for Horse Manure

Abstract Horse manure is one of the highest potential biowastes for heat and power generation. This paper investigates the experimental and mathematical modeling of thermochemical conversion for horse manure. As one type of thermochemical conversions, the pyrolysis process was carried out at eight different heating rates on horse manure using three parameters: The extent of reaction, the rate change of the extent of reaction and Differential Thermal Analysis (DTA), all used to determine kinetic data that will be validated with a mathematical model. Slow pyrolysis: below 15 °C/min showed optimistic results of obtaining exothermic reaction over a wide range of temperature which makes it self-sustainable with steady heat generation. Also, low heating rates allowed a quasi-equilibrium state through slow heating with a minimum delay in response for any transient error that could be generated from Differential Thermogravimetry (DTG) device.

Thermo‐oxidative degradation behavior of poly(vinyl chloride) insulation for new and overloaded wires via TG‐FTIR

AbstractWhen a poly(vinyl chloride) (PVC) wire experiences overload failure, the internal structure of the insulation changes to become overloaded insulation and the fire hazard changes. In this study, the thermo‐oxidative degradation behavior of new and overloaded PVC insulation materials was analyzed using coupled thermogravimetric‐Fourier transform infrared spectroscopy (TG‐FTIR). The thermo‐oxidative degradation results show that the first two stages of thermo‐oxidative degradation of PVC insulation are important stages for measuring fire hazard. In addition, the onset temperature of thermo‐oxidative degradation of overloaded PVC insulation was increased. The activation energies of the first two stages of the overloaded PVC insulation increased by 7.7% and 27.0%, respectively, compared to the new PVC insulation. And the reaction mechanism is changed. The FTIR results indicate that the increased amount of volatile organic compounds and CO2 generated during the pyrolysis of the overloaded PVC insulation may result in the generation of more heat and smoke during combustion, thus increasing the fire hazard.

A near-resonant excitation strategy to achieve ultra-low threshold GaN polariton lasing.

A near-resonant excitation strategy is proposed and implemented in a 4-µm-thick GaN microcavity to realize an exciton-polariton condensate/lasing with low threshold. Strong exciton-photon coupling is demonstrated, and polariton lasing is realized with an ultra-low threshold excitation power density of about 13.3 W/cm2 at room temperature. Such an ultra-low threshold is ascribed to the implementation of the near-resonant optical excitation strategy, which enables acceleration of the exciton and polariton relaxation and suppression of the heat generation in the cavity, thereby reducing the energy loss and enhance the cavity excitation efficiency.

Control of Anisotropy and Magnetic Hyperthermia Effect by Addition of Cobalt on Magnetite Nanoparticles.

Magnetic hyperthermia (MH) has emerged as a promising technology with diverse applications in medical and technological fields, leveraging the remote induction of temperature elevation through an alternating magnetic field. While Fe3O4 nanoparticles with an average size around 12-25 nm are commonly employed in MH systems, this study introduces a strategy to produce smaller particles (less than or equal to 10 nm) with enhanced heating efficiency, as measured by specific power absorption (SPA). We conducted an exhaustive and detailed investigation into the morphological and magnetic properties of CoxFe3-xO4 nanoparticles, aiming to optimize their MH response. By varying the Co content, we successfully tuned the effective magnetic anisotropy while maintaining saturation magnetization nearly constant. The MH analysis indicates that these nanoparticles predominantly heat through the Néel mechanism, demonstrating robust reproducibility across different concentrations, viscosity mediums, and ac field conditions. Notably, we identified an optimal anisotropy or Co concentration that maximizes SPA, crucial for developing magnetic systems requiring particles with specific sizes. This work contributes to advancing the understanding and application of MH, particularly in tailoring nanoparticle properties for targeted and efficient heat generation in various contexts.

Synthetic ester-based forced flow immersion cooling technique for fast discharging lithium-ion battery packs

Rapid advancements in Li-ion battery technology are being made to meet the growing demand for efficient energy storage solutions in electric vehicles and portable electronics. However, heat generation during rapid charging and discharging remains a significant challenge, as it can lead to overheating, fire, and explosion. To address this issue, battery thermal management systems require improvements in cooling strategies. This study aims to optimize the thermal performance of Li-ion battery packs during fast discharge operation by single-phase synthetic ester oil-based forced flow immersion cooling (FFIC) technique. The study analyzes the thermal performance of the FFIC of a 4S2P LIB pack based on various flow rates, pressure drops, and pump power consumption and compares it with various conventional cooling methods and dielectric fluids. The MSMD-based NTGK battery modeling approach is used to analyze the electrical and thermal characteristics of the battery pack at 3C discharge and environmental temperature of 25 °C. The simulation findings revealed that the synthetic ester oil has a superior cooling effect than mineral oil in the 4S2P Li-ion battery pack. The experimental results showed that the synthetic ester-based FFIC Li-ion battery pack achieves an optimal pack temperature of 31.3 °C and uniform temperature distribution at the flow rate of 5 L/min and pressure drop of 228.44 Pa. Moreover, FFIC reduces temperature rise by 51 % compared with natural air convection and 35 % compared with static flow immersion cooling (SFIC) in the 4S2P lithium-ion battery pack. Also, the practical significance of the SEO-based FFIC immersion cooling technique is assessed across extreme climate zones such as −10 °C and 40 °C and determined its superior performance in Li-ion batteries. Hence, this study proved that the FFIC technique is suitable for Li-ion batteries in electric vehicle applications in terms of optimal performance, reliability, and safety during high-current discharge operations.

Systematic Concept Study of Brayton Batteries for Coupled Generation of Electricity, Heat, and Cooling

Systematic Concept Study of Brayton Batteries for Coupled Generation of Electricity, Heat, and Cooling

Thermal Management of Lithium-Ion Battery Pack Using Equivalent Circuit Model

The design of an efficient thermal management system for a lithium-ion battery pack hinges on a deep understanding of the cells’ thermal behavior. This understanding can be gained through theoretical or experimental methods. While the theoretical study of the cells using electrochemical and numerical methods requires expensive computing facilities and time, the Equivalent Circuit Model (ECM) offers a more direct approach. However, upfront experimental cell characterization is needed to determine the ECM parameters. In this study, the behavior of a cell is characterized experimentally, and the results are used to build a second-order equivalent electrical circuit model of the cell. This model is then integrated with the cooling system of the battery pack for effective thermal management. The Equivalent Circuit Model estimates the internal heat generation inside the cell using instantaneous load current, terminal voltage, and temperature data. By extrapolating the heat generation data of a single cell, we can determine the heat generation of the cells in the pack. With the implementation of the ECM in the cooling system, the coolant flow rate can be adjusted to ensure the attainment of a safe operating cell temperature. Our study confirms that 14% of pumping power can be reduced when compared to the conventional constant flow rate cooling system, while still maintaining the temperature of the cells within safe limits.

Evaluating the Deicing Performance of Copper Sulfide Nanoparticle-Infused Transparent Photothermal Coatings on Glazing: An Integrative Experimental and Simulation Study

This study presents an efficient approach to fabricating photothermal coatings using copper sulfide (CuS) nanoparticles for effective deicing on glass. The influence of nanoparticle shape on light absorption was economically evaluated using Finite Different Time Domain (FDTD) simulations, identifying CuS nanorods as the optimal choice in terms of light absorption and heat generation. Simulation results guided the fabrication of transparent photothermal coatings incorporating CuS nanorods and transparent acrylic resin paint. Deicing tests under 808 nm illumination demonstrated efficient active deicing potential of the developed coating covered with a 3mm-thick ice layer, raising the surface temperature from-20.0 °C to 42.5 °C within 400s. This combined simulation guidance and test validation approach introduces a cost-effective method for designing high-performance deicing coatings embedded with photothermal nanoparticles.

Synergetic impact of volcanic ash and calcium carbide residue on the properties and microstructure of cementitious composites

The synergetic impact of using volcanic ash (VA) and calcium carbide residue (CCR) on the engineering properties of cementitious mortar was assessed. Cement was replaced with VA at 0–40 % by mass and/or CCR at 0–20 % by mass. Blended mortars were tested for flow, setting time, compressive strength, and ultrasonic pulse velocity (UPV). The flow increased when using VA but decreased with the inclusion of CCR. Compared to the cement-based control mix, ternary mixes had a lesser flow. The impact of VA replacement on the initial and final setting times was marginal until a substitution rate of 40 %, after which the setting times were prolonged. Similarly, the setting time was extended with CCR replacement. The compressive strength and UPV improved with the use of 10–20 % VA and/or 5 % CCR for binary and ternary mortar mixes, with the highest strength of 55.4 MPa and UPV of 4490 m/s being recorded for the mix comprising 20 % VA and 5 % CCR. Mixes were further analyzed through isothermal calorimetry, X-ray diffraction, and scanning electron microscopy. The cumulative heat generation was reduced for binary and ternary mixes except for those containing 20 % VA only. The microstructure analysis highlighted the formation of C-S-H and C-A-S-H as reaction products and the consumption of Ca(OH)2. This study provides novel insights into optimal combinations of VA and CCR for superior mortar performance, offering practical approaches to reducing cement content and lowering carbon emissions without compromising performance.

Challenges and opportunities for the application of digital twins in hard-to-abate industries: a review

The energy-intensive industry, heavily reliant on heat generation processes, faces the critical challenge of drastically reducing greenhouse gas emissions. This study reviews the potential of digital twin technology in decarbonizing combustion-dependent manufacturing processes. While primarily focusing on scholarly articles, our analysis may not cover all current industrial practices and digital twin implementations. This paper highlights challenges and opportunities in deploying practical digital twins for industrial furnaces within the Industry 4.0 framework. Digital twins, integrating real-time simulation models with predictive capabilities, aim to enhance industrial furnaces’ design, operation, and maintenance by combining high-fidelity simulations with data-driven modelling techniques. The findings indicate that digital twins can facilitate the transition to furnace electrification and adopting zero-carbon fuels, significantly reducing emissions and optimizing overall furnace performance. However, challenges like model reliability and high upfront investments in IT and connectivity infrastructures limit their widespread adoption. Despite these limitations, ongoing technological advancements predict a rapid expansion of digital twin applications in industrial furnaces, making them indispensable for achieving decarbonization goals in energy-intensive industries.

Suction influence on magneto-convective fluid flow embedded in a permeable media under internal friction

This work examines the natural convection flow of an incompressible, viscous, and electrically conducting fluid down a vertical flat plate in the presence of conduction, as well as the effects of suction, magnetic field, viscous dissipation, porous medium, and heat generation. The governing momentum and energy equations have numerical solutions. The impacts of suction, heat production, magnetic, porosity, and viscous dissipation parameters on two-dimensional flow are discussed. Graphical representations of the velocity profile, temperature distribution, skin friction, rate of heat transfer, and surface temperature distribution are shown. The presence of porous media and improving suction values improves the friction drag but diminishes the energy transfer. The thermal production parameter raises the energy inside the flow but diminishes the heat transfer coefficient. This work attempts to offer important insights into these intricate processes by examining the effects of controlling factors including magnetic fields, porous medium, and suction parameters. This research conclusion may find applications in coolers, heat exchangers, and environmental remediation technologies that are more effective, advancing engineering and sustainable practices.

Thermal properties of cooling tube battery pack embedded with triangle umbrella-shaped cellular structure

To further enhance heat dissipation efficiency and temperature uniformity of battery pack, a novel cooling tube battery pack embedded with triangle umbrella-shaped cellular structure (TUCS) with negative Poisson’s ratio (NPR) is proposed. Firstly, heat generation models of battery cell are derived and temperature rise tests are conducted to verify the accuracy of heat generation theory and simulation models of lithium battery cell. Meanwhile, cooling tube battery pack with bidirectional serpentine tube is established, and the influences of different flow rates and directions of coolant, diameter of cooling tube and spoiler columns on heat dissipation efficiency of cooling tube battery pack are investigated through simulation analysis. Moreover, relative density of TUCS is calculated and thermal conductivity expressions of TUCS are derived by Maxwell-Eucken model. Subsequently, the embedded TUCS is taken as the medium to conduct heat between cooling tubes and battery modules. Then, the influences of structural parameters of TUCS on heat dissipation efficiency of cooling tube battery pack are determined. Further, the optimal TUCS with the needs of high heat dissipation efficiency, superior temperature uniformity and more lightweight space of battery pack is achieved. Similarly, density gradient of the TUCS can be defined and impacts of TUCS with density gradient distribution on thermal performances of battery pack are investigated. Eventually, the highest temperature and maximum temperature difference of the optimal cooling tube battery pack, cooling tube battery pack embedded with the optimal TUCS and cooling tube battery pack embedded with the optimal gradient distribution TUCS are obtained. Compared with the optimal cooling tube battery pack, the highest temperatures of another two cooling tube battery packs decrease 16.50 % and 16.48 %, and the corresponding maximum temperature differences decrease 93.06 % and 93.20 %, respectively. Meanwhile, the highest temperature and maximum temperature difference of another two battery modules are 303.76 K and 3.76 K at 5C discharge rate. The proposed cooling tube battery pack with the optimal gradient distribution TUCS can decrease the highest temperature and maximum temperature difference effectively.

Suction influence on magneto-convective fluid flow embedded in a permeable media under internal friction

This work examines the natural convection flow of an incompressible, viscous, and electrically conducting fluid down a vertical flat plate in the presence of conduction, as well as the effects of suction, magnetic field, viscous dissipation, porous medium, and heat generation. The governing momentum and energy equations have numerical solutions. The impacts of suction, heat production, magnetic, porosity, and viscous dissipation parameters on two-dimensional flow are discussed. Graphical representations of the velocity profile, temperature distribution, skin friction, rate of heat transfer, and surface temperature distribution are shown. The presence of porous media and improving suction values improves the friction drag but diminishes the energy transfer. The thermal production parameter raises the energy inside the flow but diminishes the heat transfer coefficient. This work attempts to offer important insights into these intricate processes by examining the effects of controlling factors including magnetic fields, porous medium, and suction parameters. This research conclusion may find applications in coolers, heat exchangers, and environmental remediation technologies that are more effective, advancing engineering and sustainable practices.

Estimation of overcharge-induced degradation state in lithium-ion cells using differential thermal voltammetry and distribution of relaxation times

Overcharge is recognized as a significant factor contributing to the degradation and potential thermal runaway of Li-ion cells. In this study, a novel approach is proposed to estimate the extent of overcharge-induced degradation in 18,650-type Li-ion cells with NCA cathodes and graphite anodes. Experimental results reveal abnormal heat generation and capacity loss due to overcharge-induced degradation. Using Differential Thermal Voltammetry (DTV) and Distribution of Relaxation Times (DRT) methods, ten degradation factors (DFs) that reflect the extent of degradation are identified. Through Pearson correlation analysis, the height of peak P1 in DTV and S2 in DRT are identified as the most indictive parameters to estimate degradation. Next, a predictive model based on Kriging deep learning method is developed using these parameters, which enables precise estimation. Validation results for the model demonstrate outstanding predictive accuracy, with a mean absolute percentage error (MAPE) of 3.25 % and a root mean square error (RMPE) of 3.62 %. The proposed methodology not only offers a robust approach to estimate overcharge-induced degradation of Li-ion cells, but also provides valuable insights for enhancing the monitoring and management capabilities of battery system.

Effect of Preload Force on Heat Generation of Li(Ni0.8Co0.1Mn0.1)O2/SiOx-C System Batteries: The Discharge Process

Effect of Preload Force on Heat Generation of Li(Ni0.8Co0.1Mn0.1)O2/SiOx-C System Batteries: The Discharge Process

A numerical simulation of heat transfer performance on MHD nanofluids in porous metal for enhancing CPU cooling efficiency

The main goal of this study is to enhance CPU cooling efficiency using nanofluids, and the novelty of the study lies in the investigation of heat transfer and convective flow of MHD nanofluid through porous metal structures and foam heat sink/source to improve CPU cooling efficiency. The governing equations for the flow model are solved using the BVP4C with MATLAB package through shooting techniques. The effects of various parameters on velocity, temperature fields, HT and drag force are discussed through graphical simulations. The results indicate that as the Reynolds and Darcy numbers rise, fluid flow velocity undergoes unique alterations. Higher Reynolds and Darcy numbers result in cooler temperatures, while higher heat generation lead to warmer temperatures.Boosting Prandtl number improves HT by 52% with Cu nanoparticles, whereas elevating heat generation values reduce HT by 6.43% more efficiently with Cu nanoparticles than Al2O3 nanoparticles. Raising the Hartmann number would boost drag force, but the Darcy number opposes it. An increase in Hartmann number leads to a decrease in HT by 30.16% for Al2O3-H2O nanofluids and 47.81% for Cu-H2O nanofluids. The findings contribute to the development of advanced computing devices, paving the way for more efficient and reliable electronic systems in various applications.

Numerical modeling of heat flux in ultrasonic-assisted grinding of difficult-to-cut materials with a pressurized lubrication system

The temperature measurement during grinding process is difficult due to work–wheel interactions and nearby coolant layers. Surface integrity also gets affected by the grinding burns caused due to high heat generation. Therefore, the theoretical temperature estimation could provide prior detection of grinding burns. This article presents an analytical model to predict the heat flux in pressurized lubricated ultrasonic-assisted surface grinding of Nimonic 80 A using Cubic Boron Nitride (cBN) grinding wheel (vitrified grinding bond, grit 80/100, concentration 100%). In this process, the high frequency of ultrasonic vibration and low amplitude is employed to vibrate the workpiece. In the current modeling approach, the motion analysis of grains has been estimated initially, which provided the effective grinding force. This effective grinding force was then utilized to obtain the analytical model of heat flux. Finally, the model was formulated by considering the effect of heat conducted into the material and heat released due to the lubrication system. The established model comprised the effects of lubricating and machining parameters such as dynamic viscosity of cutting fluid, pressure, diameter and length of cutting fluid pipes, width of cut, frequency, speed of table, amplitude, depth of cut and speed of the wheel. This numerical model revealed affirmative results substantiated by experimentally procured data. This developed model can add to the direction of sustainable grinding approach.

Modeling and simulation of temperature field in high-shear and low-pressure grinding with liquid-body-armor-like grinding wheel

High-shear and low-pressure grinding using liquid-body-armor-like grinding wheel is a new grinding process. It has a great potential in the field of precision and ultra-precision machining. To clarify the unclear grinding heat characteristics, heat generation mechanism, and heat source distribution of the liquid-body-armor-like grinding wheel, a temperature field model was developed for high-shear and low-pressure grinding with ABAQUS. The thermal characteristics of the new grinding wheel were investigated by studying the heat flux and convective loads under different grinding parameters. The effectiveness of the heat model was validated through high-shear and low-pressure grinding experiments. The simulation results closely matched with the experimental results, with an average error of 5.84 % and a minimum error of 0.94 %. The grinding temperature decreased gradually from the centre of the heat source towards the edge of the workpiece in both horizontal and vertical directions. The temperature raised with the increase of the grinding velocity, ranging from 39.66 °C at 4 m/s to 77.82 °C at 14 m/s. It decreased with the workpiece feed rate, dropping from 39.66 °C at 500 mm/min to 32.00 °C at 3000 mm/min. As the normal grinding force increased, it gradually increases from 30.80 °C to 39.66 °C. The grinding temperature of the liquid-body-armor-like grinding wheel was lower than that of the traditional grinding wheel.