Heat Generation Research Articles

Radiation impact on heat and mass transfer of an unsteady MHD nanofluid flow past an exponentially accelerating vertical plate with heat generation

This paper comprehensively analyzes the consequences of thermal radiation on natural convection, electrical and thermally conducted water-based flowing nanofluid past an exponentially accelerating surface. The paper investigates the thermal and momentum boundary layers with the effects of radiation and heat generation on the nanofluid flow. The magnetic field acts perpendicular to the flow direction. The non-dimensional governing equations were numerically solved using the Finite Difference Method (FDM) and illustrated through the use of MATLAB software. Thermal radiation enhances the nanofluid temperature and velocity, an essential phenomenon for designing solar collectors. The heat generation factor reduces the skin friction of the flow. It improves heat transfer by convection rather than conduction mode, enhancing the velocity and dropping the temperature of the nanofluid. The influence of some dimensionless parameters on the nanofluid velocity and temperature led to this paper's conclusion. Mass and heat transmission are fundamental due to their daily applications, including human body temperature regulations, electronic devices, and heating/cooling systems.

Analytical simulation of mixed convective Williamson nanofluid flow above a stretched Riga plate considering viscous dissipation effects

This work examines, accounting for viscous dissipation, an analytical simulation of mixed convection heat transfers in a Williamson blood base nanofluid flow on a stretched Riga plate (RP). The Lorentz force, which influences fluid dynamics, is produced by the alternating magnetic fields that comprise the RP. The flow characteristics are further complicated by the blood base Williamson nanofluid’s (WN) non-Newtonian behavior. The governing partial differential equations (PDEs) for momentum and energy are transformed into a set of nonlinear ordinary differential equations (NODEs) by similarity transformations. We solve these equations analytically using the homotopy analysis method (HAM). We investigate in detail how the temperature and velocity profiles (VPs) are affected by significant parameters as the Williamson parameter (WP), viscous dissipation, volume friction of nanoparticles, modified Hartmann number (MHN), heat generation parameter and Biot number (BN). The findings show that the thermal conductivity (TC) of nanoparticles is increased, improving the efficiency of heat transfer. Moreover, a Lorentz force generated by the RP considerably alters the temperature and flow fields. With regard to the design and optimization of thermal systems utilizing complex boundary conditions (BCs) and non-Newtonian nanofluids, this work offers significant new insights.

Thermal inspection on MHD Prandtl fluid flow past a stretching sheet in the presence of heat generation/absorption and suction/injection

Abstract For the past several years, researchers have been investigating the thermal boundary layer behavior under various assumptions due to contemporary requirements. From the existing literature, it has been noticed that no investigation has been conducted to examine the thermal and mass transport of a magnetohydrodynamic (MHD) flow of a Prandtl fluid past a stretching sheet with heat generation/absorption and suction/injection. To address this gap, this study looks at how the changed thermal flux, heat generation/absorption, and suction/injection affect the convective flow of MHD Prandtl fluid over a stretching surface. The governing system of nonlinear partial differential equations (PDEs) has been reduced to a system of ordinary differential equations (ODEs) through appropriate transformations. The desired numerical solutions of the resulting ODEs have been obtained using the bvp5c MATLAB package. We have analyzed and presented the effects of the physical parameters on the velocity, temperature, and concentration fields using graphs and tables. Also, the drag coefficient, heat, and mass transport rates were examined. Additionally, an entropy analysis has been conducted to explore the reusability of heat production. It has been observed that intensifying the magnetic and porosity parameters reduces the flow velocity while increasing the Eckert number, heat generation parameter, and the Biot number significantly increases the temperature. The concentration drops with an increase in the Schmidt number and the chemical reaction parameter. This study holds significant implications for industries that rely on drug delivery, heat exchanger technology, polymerization, and refining processes.

Energy Efficiency in Portuguese Traditional Cheese Industries: A Comprehensive Case Study

In Portugal, cheese holds a prominent position as a major dairy product, with traditional varieties enjoying widespread acclaim. A number of these cheeses have earned Protected Designations of Origin status, showcasing their unique qualities and regional significance. Notable examples include “Serra da Estrela”, “Serpa”, and “Terrincho”. The production of cheese relies heavily on heating and cooling processes, which account for a substantial portion of the total energy consumed. This research endeavour undertakes a detailed description and analysis of traditional cheesemaking practices within Portugal’s interior central region, with a particular emphasis on the economic and energetic efficiency of refrigeration systems. For this purpose, thirty-one traditional cheese production facilities were examined and classified into two distinct groups: Traditional Industrial Producers and Traditional Handmade Producers. The analysis was conducted through two separate case studies. The findings reveal that a significant 58% of the energy consumed by these facilities is attributed to electrically powered cooling systems, encompassing components such as fans, compressed air systems, and illumination. Within the production processes, fuel combustion, primarily naphtha or propane, serves the purpose of water heating and steam generation. Based on energy consumption reports, the Specific Energy Consumption of electricity was determined to be 0.283 kWh/lRM for TIP and 0.169 kWh/lRM for THP. Furthermore, several linear regression models were developed to explore the relationships between parameters such as cold room volume, compressor power, and raw material quantity. The study also identified key factors contributing to reduced energy efficiency within the facilities. These factors include inadequate insulation of buildings and cold rooms, outdated and poorly maintained refrigeration equipment situated in suboptimal locations, and cold rooms and compressors that are oversized and not optimised for efficient operation.

Heat transfer analysis of a fully wetted inclined moving fin with temperature-dependent internal heat generation using DTM-Pade approximant and machine learning algorithms

Heat transfer analysis of a fully wetted inclined moving fin with temperature-dependent internal heat generation using DTM-Pade approximant and machine learning algorithms

A comparative study of casson and Jeffrey nanofluids flowing through the radiative bidirectional stretched surface with porous media

A comparative study of radiative Casson and Jeffrey fluids flows generated by the chemically reactive bidirectional stretched sheet is presented. Energy and mass species analysis is performed under radiative heat generation impacts. The Robin’s heat and mass conditions are imposed for the analysis of considered model. The boundary-driven equations are simplified into one independent variable equation by the implication of similarity constraints. The resulted model is tackled by the help of homotopic scheme. The results of various parameters are sketched and interpreted for both Casson and Jeffrey nanofluids. The convergence is expressed through numeric benchmarks and graphical form. The numeric evaluation of Sherwood and Nusselt number is presented against the versatile parametric values. The results showed that the higher velocity curves appeared in Casson nanofluid case as comparative to case of Jeffrey nanofluid. The temperature heat generation constraints boosted the temperature of both Casson and Jeffrey nanofluids. The incrementing trend of chemical reactive and Lewis number resulted weaker concentration profiles for Jeffrey and Casson fluids. The conducted research model has magnificent appliances in solar energy devices, chemical reactors, solar reservoirs, nuclear power plants, heat reservoirs, microwave oven, thermal radiant, thermal imaging and many others.

Entropy Generation Modeling in Dynamic Local Thermal Non-Equilibrium Systems Using Neural Networks

The study of entropy generation in thermal non-equilibrium (TNE) states has significant implications for optimizing thermal management systems and understanding heat transfer mechanisms in permeable media. This study investigates the entropy properties in a thermal non-equilibrium (TNE) state within double-lid-driven enclosures filled with a permeable medium. Unlike the temperature equilibrium state, the entropy approach is described by two equations: one for the irreversibility of the mixture phase and one for the irreversibility of the medium phase. High mixed convection is considered due to the motion of the non-facing edges (left-side and upper edges). Four cases based on the direction of motion are examined: Case 1, where the left-side and top edges move in the negative and positive directions of the Y- and X-axes, respectively; Case 2, where the upper and left-side edges move in the negative and positive directions of the X- and Y-axes, respectively; and Cases 3 and 4, where the edges move in the positive and negative directions of the respective axes. Heat generation within the flow domain is considered for both the suspension and medium phases. The governing system is solved numerically using finite volume techniques with the SIMPLER algorithm. The obtained data are used to predict key quantities, such as the heat transfer rate, under the influence of major factors using an effective artificial neural network (ANN) analysis. The main findings show that the solid phase entropy is higher in Case 3 compared to the other cases. Additionally, Case 2 results in a minimum solid phase Nusselt coefficient at the center of the active boundary.

Contrasting the Intraseasonal Precipitation in the Western and Eastern North Pacific During Boreal Winter

AbstractThe wintertime North Pacific exhibits two types of intraseasonal periodicity in daily precipitation, with a period of 10–20 and 30–90 days in the western and eastern North Pacific. This study aims to identify and compare characteristics and mechanisms of intraseasonal precipitation in these two regions using daily observational data. Our results indicate their notable differences in atmospheric circulations and dynamical processes, despite similarities in moisture sources. A wave train associated with the intraseasonal precipitation in the western North Pacific characterized by anomalous cyclones and anticyclones from West Siberia into the North Pacific is observed, accompanied by anomalous wave activity. By diagnosing local finite‐amplitude wave activity (LWA) budget, we demonstrate that the baroclinic eddy generation initiates the upstream growth of wave activity, whereas its downstream development is primarily attributed to the zonal advection of wave train. The upstream wave train induces barotropic and baroclinic instabilities in Kuroshio‐Oyashio extension (KOE). In contrast, the anomalous atmospheric circulations related to intraseasonal precipitation in the eastern North Pacific feature a tripolar structure, with downstream propagation of wave activity from the eastern North Pacific to the North American continent. Diabatic heating, along with local eddy generation, contributes to the upstream growth of wave activity. Residual term, possibly linked to the wave activity dissipation associated with wave breaking, extends the wave activity downstream. Thermal and baroclinic instabilities, associated with the diabatic heating and local eddy generation, create favorable conditions for the precipitation. This study may contribute to the improvement of intraseasonal precipitation prediction over the pan‐North Pacific region.

Human 3D Lung Cancer Tissue Photothermal Therapy Using Zn- and Co-Doped Magnetite Nanoparticles.

Iron oxide-based nanoparticles are promising materials for cancer thermal therapy and immunotherapy. However, several proofs of concept reported data with murine tumor models that might have limitations for clinical translation. Magnetite is nowadays the most popular nanomaterial, but doping with distinct ions can enhance thermal therapy, namely, magnetic nanoparticle hyperthermia (MNH) and photothermal therapy (PTT). In this study, we used a 3D alveolar reconstructed A549 lung cancer tissue model and investigated the thermal properties, toxicity, and impact of the thermal dose on tissue viability and inflammatory response using magnetite codoped with 40% Zn and 2% Co divalent ions. The ZnCo-doped magnetite nanoparticles are not toxic up to an NP concentration of 30 mg/mL. PTT showed a better heat generation response than MNH under the evaluated conditions, while NP showed a high external photothermal conversion efficiency of ∼1.3 g·L-1·cm-1 at 808 nm. PTT study is carried out at different temperatures, 43 and 47 °C, for 15 min. Tissue viability decreased with increasing thermal dose, while intracelullar ROS levels increased, mitochondrial activity decreased, and active caspase-3 increased, suggesting cell death via apoptosis. Nanoparticles and PTT did not influence the cytokine TNF, IL-10, IL-1B, and IL-12p70. In contrast, IL-6 and IL-8 were triggered by NP and PTT. Increased expression of IL-6 and IL-8 with higher thermal doses is correlated with tissue injury results, suggesting the potential role in activating and attracting immune cells to the site of thermal-mediated tissue injury.

Thermodynamic Analysis of Pumped Thermal Energy Storage System Combined Cold, Heat, and Power Generation

Aiming at problems such as the low efficiency of renewable energy conversion and the single energy flow mode, this paper proposes a heat pump energy storage system combining cold, heat and power generation to achieve the purpose of diversified utilization of renewable energy. The system is suitable for buildings requiring cooling, heating/domestic hot water production and electricity. This paper mainly uses MATLAB for numerical calculations, selects several key cycle parameters to calculate and analyze the thermodynamic performance of the system, and uses the genetic algorithm and TOPSIS decision method to carry out fine design of the system working conditions. Through the multi-objective optimization calculation and the optimal solution, the system can achieve a total energy efficiency of 2.39 and a high thermal economic performance, indicating that the system can achieve the goals of cooling, heating water and power supply and providing ideas for the application of the multiple energy storage system.

NanoTrackThera Platform for Real-Time, In Situ Monitoring of Tumor Immunotherapy and Photothermal Synergistic Efficacy.

Cancer is one of the leading causes of death worldwide, posing a significant threat to human health. Although immunotherapy has shown promise in cancer treatment, its efficacy is often compromised by tumor immune evasion, which hinders treatment outcomes. Therefore, combining immunotherapy with other therapeutic approaches to enhance its effectiveness has become an increasingly accepted strategy in clinical practice. In response to this need, a nanotechnology-based platform, NanoTrackThera (NTT), which enables both combination therapy and real-time efficacy diagnosis, is developed. Using nonsmall cell lung cancer (NSCLC) as a model, the NTT platform integrates immunotherapy and photothermal therapy (PTT) to enhance the activity of natural killer (NK) cells, employ immune checkpoint inhibitors, and leverage the heat generation from self-assembled nanoparticles under near-infrared (NIR) irradiation to directly kill cancer cells. Simultaneously, the nanoplatform incorporates dual detection capabilities through fluorescence imaging and photoacoustic imaging. With these multimodal imaging techniques, the platform can achieve real-time, in situ, tracking of tumor biomarker changes during treatment, providing precise feedback on the efficacy of the combined immunotherapy and photothermal therapy. The NTT platform significantly enhances therapeutic efficacy while enabling real-time monitoring of dynamic changes in key tumor biomarkers, providing a solution for personalized and adaptive precision therapy.

Will More Cement in Your Mixture Hurt You?

An old rule of thumb states that if you need more strength in a concrete mixture, just throw more cement at it. Sometimes that helped, sometimes not. Today many engineers realize that there are many other variables in a mixture that effect strength as much as, or more than, cement content. They also realize that increased cement content in a concrete mixture can lead to a number of effects that may reduce the life of the pavement. Many properties of concrete are adversely affected by over-cementing the mixture. These are discussed to help the reader understand why optimizing the cement content will help produce an efficient mixture that will meet the project requirements. By first determining the voids in the aggregate portion of the concrete mixture and then increasing that volume by an amount necessary for workability, a volume of paste can be determined that will approximate the optimum cementitious content to both maximize strength and also provide a workable mixture. Also discussed are the effects of increasing the cement content in a concrete mixture, including durability, strength, heat generation, shrinkage, set time, workability, CO2 footprint, as well as cost.

Tides on Lava Worlds: Application to Close-in Exoplanets and the Early Earth–Moon System

Abstract Understanding the physics of planetary magma oceans has been the subject of growing efforts, in light of the increasing abundance of solar system samples and extrasolar surveys. A rocky planet harboring such an ocean is likely to interact tidally with its host star, planetary companions, or satellites. To date, however, models of the tidal response and heat generation of magma oceans have been restricted to the framework of weakly viscous solids, ignoring the dynamical fluid behavior of the ocean beyond a critical melt fraction. Here we provide a handy analytical model that accommodates this phase transition, allowing for a physical estimation of the tidal response of lava worlds. We apply the model in two settings: the tidal history of the early Earth–Moon system in the aftermath of the giant impact, and the tidal interplay between short-period exoplanets and their host stars. For the former, we show that the fluid behavior of the Earth's molten surface drives efficient early lunar recession to ~25 Earth radii within 104–105 yr, in contrast with earlier predictions. For close-in exoplanets, we report on how their molten surfaces significantly change their spin–orbit dynamics, allowing them to evade spin–orbit resonances and accelerating their track toward tidal synchronization from a gigayear to megayear timescale. Moreover, we reevaluate the energy budgets of detected close-in exoplanets, highlighting how the surface thermodynamics of these planets are likely controlled by enhanced, fluid-driven tidal heating, rather than vigorous insolation, and how this regime change substantially alters predictions for their surface temperatures.

Lattice thermal conductivity in CrSBr: the effects of interlayer interaction, magnetic ordering and external strain.

With the continuous development of digital information and big data technologies, the ambient temperature and heat generation during the operation of magnetic storage devices play an increasingly crucial role in ensuring data security and device stability. In this study, we examined the lattice thermal conductivity of the van der Waals magnetic semiconductor CrSBr from bulk to monolayer structures using first-principles calculations and the phonon Boltzmann transport equation. Our results indicated that lattice thermal conductivity show anisotropy and CrSBr bilayer exhibits lower thermal conductivity at all temperatures. Through the analysis of phonon spectra. phonon lifetime, heat capacity, scattering probability, phonon-phonon interaction strength, we demonstrated that Cr-Br antisymmetrical stretching vibrations and phonon band gap are the main factors, which exhibit considerable dependence on layer number, magnetic ordering and strain effects. These results offer a comprehensive insight into phonon transport phenomena in van der Waals magnetic materials.&#xD.

Analyzing Cutting Temperature in Hard-Turning Technique with Standard Inserts Through Both Simulation and Experimental Investigations

The cutting temperature in hard turning is extremely high, which reduces tool life, lowers machined-surface quality, and affects dimensional control. However, hard turning differs greatly from conventional turning in that the cutting process mainly happens at the tool-nose radius due to the extremely shallow depth of the cut. This paper provides a comprehensive and systematic analysis of this issue based on an evaluation of tool geometry in hard turning via finite element analysis (FEA) simulations and experiments. The effect of tool angles on cutting temperature in hard turning is analyzed. The impacts of cutting-edge angle, rake angle, inclination angle, and average local rake angle on the cutting temperature are investigated via central composite design (CCD). The simulated results and the empirically measured cutting temperature exhibit comparable patterns, with a minor 2% difference. Increasing the cutting-edge angle, negative rake angle and negative inclination angle enhances the local negative rake angles of the cutting-edge elements at the tool-nose radius involved in the cutting process. Notably, the most important component influencing cutting temperature in hard turning is the inclination angle, as opposed to normal turning, where the rake angle dominates the heat generation. Following this is the cutting-edge angle and the rake angle, which each contribute 40.75%, 32.39%, and 7.03%. These findings could enhance the application of the hard-turning technique by improving tool life and surface quality by focusing on optimizing the inclination angle.

Thermal Analysis of Electromagnetic Induction Heating for Cylinder-Shaped Objects.

Induction heating is one of the cleanest and most efficient methods for heating materials, utilizing electromagnetic fields induced through AC electric current. This article reports an analytical solution for transient heat transfer in a three-dimensional (3D) cylindrical object under induction heating. A simplified form of Maxwell's equations is solved to determine the heat generation inside the cylinder by calculating the current density distribution within the body. The temperature within the solid is found from the solution of the unsteady heat equation based on Green's function. Owing to multiple spatial dimensions and time, a separation of variables technique is used to find Green's function. In addition, an innovative algorithm is proposed to take care of the variable material properties in analytical treatment. The analytical solution for temperature is verified with the data obtained from experiments for identical operating conditions. The analytical solution is used to study the impact of heat transfer coefficient and input AC current frequency and amplitude during transient heat diffusion. Our analytical solution suggests that the temperature-dependent material properties significantly affect the thermal response within the solid. Unlike many other conventional heating methods, the thermal boundary condition changes with time in induction heating, which makes our solution much more challenging.

CFD Analysis of Thermal Conditions and Airflow Patterns in Commercial Laundry Facility using ANSYS Fluent Simulation

This study investigates thermal conditions optimization in a commercial laundry facility through Computational Fluid Dynamics (CFD) analysis using ANSYS Fluent. The research was conducted at Commercial Laundry X in Batu Pahat, Johor, Malaysia, employing a methodology that integrated experimental measurements with computational modelling. Using advanced instrumentation including Temp Sensor T310, Temp Data Logger H100, Thermal Camera T640, and The VelociCalc Multi-Function Ventilation Meter (Model 9565), the study collected empirical data across strategically positioned sampling locations. The data collected from the equipment and instrumentation were compared with the temperature contours and velocity streamlines generated by the computational model. The validated computational model, exhibiting relative errors consistently below 10%, with lowest relative error of 2.17%, successfully simulated complex airflow patterns and temperature distributions throughout the facility. The thermal analysis revealed that of the facility's operational areas exceeded recommended comfort temperatures (23°C - 27°C), with the most significant hotspot reaching 37.81°C near dryer units. This thermal concentration was primarily attributed to the combined effect of equipment heat generation and insufficient thermal dissipation, resulting in localized high-temperature zones that significantly impact the working environment. These findings highlight the critical influence of heat-intensive operations on the thermal environment, indicating poor temperature uniformity and inadequate dissipation of heat in these areas. This research focuses on developing a 3D model of a commercial laundry facility, incorporating geometric and operational characteristics. The model is validated by comparing computational results with experimental measurements of temperature contours and velocity profiles. The study provides valuable insights for optimizing ventilation strategies and equipment placement in commercial laundry facilities, contributing to the enhancement of worker comfort and operational efficiency.

Hydration Modulation Measures to Mitigate the Negative Effects of Paving Concrete in Hot Weather

Concrete Placement above a temperature of 35°C (95°F) is typically prohibited in many specifications for construction due to concerns over early-aged cracking, early stiffening, increasing setting temperature, and reduction of ultimate concrete strength etc. A common way to control or modulate the concrete placement temperature has been to cool the concrete constituents (e.g., aggregates and water) or the concrete mixture by using ice or injecting liquid nitrogen. However, these temperature modulation measures often increase the cost of the concrete. In the present study, an attempt has been made through laboratory testing to investigate the effect of hydration modulation measures such as modifying mixture proportions in terms of fly ash proportions in order to combat the negative effect of high temperature placement. Use of fly ash contents greater than 25-30% is an affective way to control the high heat generation and excessive drying shrinkage that is characteristic of high placement temperature and can mitigate the negative effect of high set temperature gradients that can result from placing artificially-cooled concrete under hot weather conditions.

Numerical Modeling and Structure Optimization for Magnetic Levitation Planar Machine Using PCB Coils

Magnetically levitated (ML) systems that incorporate PCB coils represent a growing trend in precision machining, valued for their controllable current flow and high fill factor. The size of modern power devices is decreasing to enhance power density, minimize parasitic inductance, and reduce power losses. However, due to the high resistance of PCB coils, managing heat generation has become a significant area of study. This paper seeks to optimize PCB coil design to minimize power loss and control peak temperatures in ML systems, using a numerical model. An improved magnetic node model is employed to construct the magnetic fields of an ML system. The proposed optimization method considers the interdependencies among parameters to reduce overall power loss from coil resistance and switching losses in the H-bridge circuit, while enhancing heat dissipation efficiency in steady-state operation. A heuristic multi-objective optimization algorithm is employed to optimize the design of the ML actuator. The optimization process initially focuses on the PCB coils, with the magnet size held constant. Once the optimal coil parameters are identified, the magnet volume is optimized. By integrating a theoretical analysis with simulation, this approach effectively addresses the optimization challenges and achieves the desired performance for the ML actuator. Coils and magnets are constructed based on the optimized design and tested by the magnetic field simulation software Radia, confirming the feasibility of the approach. The method was also applied to a different type of ML system for comparison, demonstrating the universality of the proposed strategy. In this optimization effort, the maximum temperature reduction reached an impressive 50 °C

Realizing low voltage-driven bright and stable quantum dot light-emitting diodes through energy landscape flattening

Solution-processed quantum dot light-emitting diodes (QLEDs) hold great potential as competitive candidates for display and lighting applications. However, the serious energy disorder between the quantum dots (QDs) and hole transport layer (HTL) makes it challenging to achieve high-performance devices at lower voltage ranges. Here, we introduce “giant” fully alloy CdZnSe/ZnSeS core/shell QDs (size ~ 19 nm) as the emitting layer to build high-efficient and stable QLEDs. The synthesized CdZnSe-based QDs reveal a decreased ground-state band splitting, shallow valence band maximum, and improved quasi-Fermi level splitting, which effectively flatten the energy landscape between the QD layer and hole transport layer. The higher electron concentration and accelerated hole injection significantly promote the carrier radiative recombination dynamics. Consequently, CdZnSe-based device exhibits a high power conversion efficiency (PCE) of 27.3% and an ultra-low efficiency roll-off, with a high external quantum efficiency (EQE) exceeding 25% over a wide range of low driving voltages (1.8-3.0 V) and low heat generation. The record-high luminance levels of 1,400 and 8,600 cd m-2 are achieved at bandgap voltages of 100% and 120%, respectively. Meanwhile, These LEDs show an unprecedented operation lifetime T95 (time for the luminance to decrease to 95%) of 72,968 h at 1,000 cd m-2. Our work points to a novel path to flatten energy landscape at the QD-related interface for solution-processed photoelectronic devices.