Optimal Heat Research Articles

Efficient improvement of high-temperature ductility in selective laser melted GH4099 superalloy by Mg microalloying and optimized heat treatment

Efficient improvement of high-temperature ductility in selective laser melted GH4099 superalloy by Mg microalloying and optimized heat treatment

Optimizing Thermal Energy Storage Using Multi-Walled Carbon Nano Tube Infused Polyethylene Glycol Composites: An Experimental and Simulation Study

Highly stable phase change materials with superior thermal properties and reliability are of utmost need for waste heat recovery applications. Due to low supercooling, non-corrosivity, and low phase separation, organic phase change materials are preferred for thermal energy storage over inorganic phase change materials. Despite their other advantages, the limited heat conductivity of organic phase change materials limits their practical use in thermal energy storage. Therefore, current research focuses on developing nano-enhanced organic phase change materials by dispersing one-dimensional thread-shaped multi-wall carbon nanotubes with different weight percentages to improve the thermal properties of the base PEG-1000 PCM. The two-step method was adopted to develop phase change material composites to establish an improved thermal network, resulting in improved thermal conductivity. An ongoing study evaluated structural stability, chemical stability, thermal property, optical absorptivity, transmissivity, and thermal reliability of the formulated nano-enhanced phase change material composites. The results demonstrated that the highest thermal conductivity of nanocomposite was improved by 104.2% at 0.7wt.% multiwall carbon nanotube. The composite's optimum latent heat and melting point were 41.5 °C & 140J/g, respectively. Additionally, the composite retained its thermal and chemical performance after being subjected to 500 thermal cyclic studies. Subsequently, a heat transfer simulation study is conducted to exhibit the effect of higher thermal conductivity of newly formulated nanocomposites for heat transfer compared to base PCM using 2-D energy simulation software.

Data-driven systematic methodology for predicting optimal heat pump integration based on temperature levels and refrigerants

Data-driven systematic methodology for predicting optimal heat pump integration based on temperature levels and refrigerants

Energy efficiency potential determination for an oil treatment and stabilization unit at the field

Relevance. The desire to increase the energy efficiency of industrial enterprises and reduce greenhouse gas emissions from their activities. Reducing specific energy consumption at large oil refineries and petrochemical plants is not new and is quite widely used. Dozens of monographs and thousands of articles are devoted to these areas. But it should be taken into account that in the oil refining industry, all crude oil, even that which does not reach the refinery, necessarily passes through oil preparation and stabilization units at the fields. Therefore, in order to create energy-efficient and environmentally friendly processes throughout the entire oil refining chain, it is necessary to increase the energy efficiency of the oil preparation and stabilization units located at the fields. There are very few research works on thermal energy integration of oil preparation and stabilization units. Aim. Determination of target design and energy values for an energy-efficient retrofit project of the heat exchange network for the surveyed oil preparation and stabilization units and of its energy efficiency potential. Methods. Pinch analysis methods are used to determine the target values of an energy-efficient retrofit project. Mathematical modeling of heat exchange processes in the heat exchange network and economic analysis were performed using the Pinch 2.02 software; the Aspen HYSYS software package was used to create a simulation engineering model of the oil preparation and stabilization units. Results. When determining the target values of the heat exchange network retrofit project, the cost of energy and heat exchange equipment, the cost of collectors for splitting process streams, and technical restrictions on the placement of heat exchanger sections were taken into account. The inclusion of fuel gas in the process stream table has allowed the definition of target parameters for the optimal unit heat exchange network design to evolve. In the process of evolution of target values, the energy efficiency potential of the surveyed oil preparation and stabilization units was determined, which shows the possibility of reducing specific energy consumption by 77%. Upon implementation of the heat exchange network retrofit project and achievement of target parameters, the following economic results will be obtained: IRR=42%, NPV=7425780 USD, DPP 4 years. Also, CO2 emissions can be reduced by 30 thousand tons per year. It should be noted that the evolution of target designation and all target values for the reconstruction project were obtained before the implementation of the heat exchange network oil preparation and stabilization units project itself.

Numerical Analysis of Magnetohydrodynamics Mixed Convection and Entropy Generation in a Double Lid‐Driven Cavity Using Ternary Hybrid Nanofluids

AbstractThe present study numerically investigates the effects of a magnetic field on mixed convection flow and entropy generation within a double lid‐driven square cavity filled with a hybrid nanofluid. The flow is induced by two isothermally heated semi‐circles located on the bottom and left walls of the cavity. The cavity is filled with a ternary composition of hybrid nanofluid (aluminum oxide/silver/copper oxide‐water) and is exposed to a uniform magnetic field. The velocity ratio of the moving lids and the radius ratio of the semi‐circles are key parameters in the analysis. The study employs the finite volume method and full multigrid acceleration to solve the coupled continuity, momentum, energy, and entropy generation equations, along with the relevant boundary conditions. Key dimensionless parameters considered include the Hartmann number (0 ≤ Ha ≤ 100), Richardson number (0.01 ≤ Ri ≤ 1), hybrid nanofluid volume fraction (3% ≤ ϕ ≤ 12%), internal semi‐circle radius ratio (β = 0.5 and 1), and velocity ratio (−2 ≤ λ ≤ 2). Results revealed that the optimal heat transfer is achieved for Ri = 0.04, Ha = 100, ϕ = 0%, β = 1, and λ = 0.5 with 63% enhancement. Moreover, the maximum entropy generation rates are obtained for the same parameters with a rate of 47%, reflecting the complex balance of enhanced heat transfer and associated irreversibility's. Results reveal also that heat transfer and entropy generation are a decreasing function of Hartmann number implying a suppress of fluid motion due to the Lorentz force. This study provides a valuable resource and parametric analysis for researchers and engineers, aiding in the design and optimization of thermal management systems for various industrial applications, including heat exchangers, nuclear reactors, and energy systems.

Metastable Microstructural States During Short-Term Heat Treatment of the High-Speed Steel PM HS 3-3-4: Modeling and Experimental Validation

Abstract Short-term heat treatments of tool steels, such as inductive hardening, target the martensitic hardening of functional surfaces from a metastable microstructural state of the multiphase system. Understanding the kinetics of the carbide dissolution, precipitation, growth, and coarsening, and their effect on the austenitic matrix is, thus, instrumental to designing optimal heat treatments. The present work investigates the influence of such processes on the powder-metallurgically produced high-speed steel DIN EN 1.3377 (PM HS 3-3-4). Starting from the as-delivered soft-annealed state, the microstructural evolution during the heat treatment was investigated. The heat treatments were simulated experimentally in a quenching dilatometer and numerically within the software package MatCalc. SEM and XRD provided detailed information about the microstructure, whereas hardness measurements deliver insights into mechanical properties. The developed MatCalc model can predict the carbide dissolution and the associated change in the chemical composition of the matrix during austenitizing as a function of temperature and time. The results in terms of the measured and computed martensite start temperature demonstrated good agreement between the experimental and simulation campaigns.

Microstructures and Mechanical Properties of SUS 630 Stainless Steel: Effects of Age Hardening in a Tin Bath and Atmospheric Environments

This study investigates the solution-aging treatment of precipitation-hardening SUS 630 stainless steel, alongside an analysis of the carbon emissions generated by the energy consumed during aging treatments. By employing atmospheric and liquid tin as aging media, the research comprehensively explores the effects of aging treatments on the characteristics of 630 stainless steel. The maximum hardness value for the 630 stainless steel was observed after atmospheric aging at 500 °C for 1 h. The given 630 stainless steel obtained its maximum hardness value after atmospheric aging at 500 °C for 1 h, indicating that the formation of secondary precipitates strengthens the steel’s performance. By leveraging the intrinsic characteristics of liquid tin, using it as an aging medium (Sn bath aging) significantly improves the efficiency of the aging process, achieving mechanical properties comparable to those of atmosphere-aged steel. The 630 stainless steel aged in a Sn bath exhibited a refined martensitic matrix with substantial precipitate formation, contributing to superior impact toughness and dynamic fatigue resistance. With an equivalent mass and performance, Sn bath aging notably reduced the duration of the treatment compared to atmospheric aging, leading to substantial energy savings and reduced carbon emissions. The Sn bath treatment, recognized in metallurgical science and heat treatment for its excellent thermal conductivity and recyclability, shows potential to enhance process efficiency and enable low carbon emissions in the heat treatment industry. By highlighting the differences between aging methods, this study provides solutions for optimizing heat treatment processes and thereby achieving industrial advancement and sustainability goals.

Optimized Heat Treatment for Electron Beam Powder Bed Fusion Processed IN718: Correlating Microstructure, Texture, and Mechanical Properties

This study investigates the microstructure and mechanical properties of Inconel 718 (IN718) manufactured via electron beam melting (EBM). The EBM‐processed IN718 exhibits a unique grain structure with columnar grains along the build direction (BD) and equiaxed grains perpendicular to it. Contrary to typical solidification textures, the strongest texture intensities are observed for (110) and (111) orientations, attributed to in situ δ phase precipitation during high‐temperature processing. The microstructure notably lacks cellular structures common in additively manufactured materials, instead featuring δ phase formed through in‐situ aging. A tailored heat treatment strategy is developed to control δ phase precipitation at grain boundaries, mitigating grain boundary sliding (GBS). This treatment results in <100> texture and large columnar grains, leading to a twofold increase in yield strength compared to the as‐printed (AP) condition. Interestingly, the AP EBM IN718 shows no signs of dynamic strain aging (DSA), distinguishing it from conventionally processed IN718. This comprehensive analysis of microstructure, texture, and mechanical behavior provides valuable insights for optimizing EBM processing and heat treatment of IN718 for enhanced performance in high‐temperature applications.

Quality of Sous Vide-Cooked Pork Loin Stored in Refrigerated Conditions

The sous vide cooking method offers advantage in preparing meat dishes in advance. This study aimed to evaluate the effect of refrigerated storage on the quality attributes of pork loin sous vide cooked under selected, optimised temperature and time parameters. Pork loin was cooked at varying temperatures (57–63 °C) and times (3.5–5.5 h), followed by refrigerated storage for up to 7 days. Analytical methods, including TBARS index for lipid oxidation, instrumental colour measurement, texture analysis, and volatile compound profiling, were used to assess changes in meat quality over time. The results indicated that heat treatment and storage time significantly influenced lipid oxidation, colour, and texture. The highest TBARS values were observed at higher cooking temperatures (61 °C and 63 °C), reflecting increased lipid oxidation. Colour changes were also temperature- and time-dependent, with a decrease in redness (a*) and an increase in lightness (L*) and yellowness (b*). Sensory evaluation revealed that juiciness, aroma intensity, tenderness, and flavour acceptability were strongly correlated with overall acceptability, while physical characteristics like colour and texture had a lesser impact. The study highlights the impact of sous vide cooking parameters on the quality and sensory attributes of pork loin, suggesting that optimised heat treatment can help preserve desirable meat characteristics during refrigerated storage.

Optimization of pyrolysis process parameters for optimal high heating value of biochar produced from rice straw

The harvest of rice leaves abundant biowaste and its utilization is being researched. Hence, this paper targets the conversion of rice straw into biochar. In this study, the vacuum-assisted intermediate pyrolysis process is used to convert the rice straw biowaste into biochar, which can be used as a fuel. The produced biochar is studied for the biochar yield and energy yield. It is further analyzed for the high heating value (HHV). This experimental investigation optimizes the processing parameters such as time and temperature to obtain the optimal HHV. The response of HHV is maximized using response surface modeling (RSM) based on a central composite design (CCD) matrix. This technique systematically investigated the influence of continuous parameters on the dependent variable. As a result, the time and temperature and their interaction have the most significant effect on the HHV of the biochar obtained from two different amounts of feedstocks. The optimal response obtained for HHV1 is 21.45 MJ/kg at time 47 min and temperature 397 °C, whereas HHV2 is 19.43 MJ/kg at time 51 min and temperature 405 °C. The Fourier transform infrared (FTIR) analysis is further used to characterize the biochar obtained at optimized parameters.

Intelligent Thermochromic Heating E-Textile for Personalized Temperature Control in Healthcare.

Heating electronic textiles (e-textiles) are widely used for thermal comfort and energy conservation, but prolonged heating raises concerns about heat-related illnesses, especially in the elderly. Despite advancements, achieving universal user satisfaction remains difficult due to diverse thermal needs. This paper introduces an intelligent thermochromic heating e-textile with an artificial intelligence (AI)-based temperature control system for optimized personal comfort and color indicators for elderly caregivers. The fabric integrates conductive yarn, temperature-induced discoloration yarn (TIDY), and polymeric optical fiber (POF) to visualize temperature changes, ensuring efficiency and comfort. Equipped with microcontrollers, ambient sensors, and Bluetooth connectivity, the system offers comprehensive intelligent heating solutions. An AI model, trained on data from 50 wearability test subjects, determines optimal heating temperatures (40-50 °C) with 5.083 mean squared error (MSE), showing a high correlation between predicted and actual comfort levels. This concept enhances thermal comfort and mitigates overheating risks, promising for wearable healthcare applications.

Optimization of drying parameters and texture properties of winter jujube slices by radio frequency combined with hot air.

In order to improve the drying quality of winter jujube slices and find the best drying process parameters, RF + HA (radio frequency combined hot air) drying technology was used in this study to study the effects of plate spacing, RF application time, and RF interval time on the quality of winter jujube slices. Vitamin C (VC) content, red and green value (a*), and drying rate (DR) were used as quality indexes, and the changing trend of texture properties was analyzed. According to the conclusion of the single-factor experiment, the orthogonal experiment is carried out, and the parameters of each factor in the orthogonal experiment are optimized by the comprehensive balance method and matrix analysis method. The results showed as follows: (1) Plate spacing, RF application, and interval time all significantly affected the drying properties in the single-factor test (p < 0.05). The VC content of winter jujube slices increased and then decreased with the increase in the three factors. (2) In the orthogonal test, the order of influence of each factor on the quality of the winter jujube tablet is plate spacing > RF interval time > RF application time. The optimum RF heat treatment parameters are plate spacing of 100 mm, RF application time of 3 min, and RF interval time of 2 min. Under these conditions, the VC content of the winter jujube slices was 258.35 mg/100 g, a* was -9.47 and the DR was 0.64 g/min. (3) RF + HA has more advantages in shortening drying time and maintaining shape, reducing hardness by 12.6 ~ 18.7% and crispiness by 13.8 ~ 20.4%, the microstructure of jujube slices shows a regular honeycomb shape. The research results provide a new drying combination mechanism and process optimization scheme for improving the drying technology of winter jujube slices in industrial production.

Excellent strength/ductility synergy by optimization of post-weld heat treatment for gas metal arc welded CoCrFeMnNi high entropy alloys with 410 stainless filler wire: High-throughput thermodynamic modelling with experimental validation

Excellent strength/ductility synergy by optimization of post-weld heat treatment for gas metal arc welded CoCrFeMnNi high entropy alloys with 410 stainless filler wire: High-throughput thermodynamic modelling with experimental validation

THERMOHYDRAULIC PERFORMANCE ANALYSIS OF ABSORBER TUBE WITH COILED WIRE TURBULATORS IN SMALL APERTURE PARABOLIC TROUGH COLLECTOR

Three-dimensional (3D) simulation using computational fluid dynamics (CFD) has been performed to investigate the impact of a coiled wire turbulator (CWT) on heat transfer and fluid flow in the absorber tube of a small aperture parabolic trough collector (PTC) under a turbulent flow regime. The PTC was modeled with a projected aperture area of 0.64 m&lt;sup&gt;2&lt;/sup&gt; and an optimized value of rim angle 90 degrees using the ray tracing tool SolTrace based on an optimum value of average heat flux (8.58 kW/m&lt;sup&gt;2&lt;/sup&gt;), and this optimum average heat flux was used as one of the boundary conditions in CFD simulation. The CFD-simulated findings for the smooth absorber tube of the PTC model are compared with the Dittus-Boelter equation for heat transfer and the Filonenko equation for friction factor. The simulated result showed an average deviation of 2.54&amp;#37; and 14.68&amp;#37; in the Nusselt number and friction factor, respectively. The effect of a wall-detached type of CWT (D&lt;sub&gt;m&lt;/sub&gt; &amp;#61; 10 mm) on thermohydraulic performance with coil pitch ratios (P/d&lt;sub&gt;h&lt;/sub&gt;) of 1, 1.5, and 2 and height ratios (e/d&lt;sub&gt;h&lt;/sub&gt;) of 0.053, 0.063, and 0.074 is considered for the analysis in the Reynolds number (Re) range of 4000-12000. The optimal value of thermohydraulic performance (&amp;#951;&lt;sub&gt;thp&lt;/sub&gt;) is obtained 1.56 for P/d&lt;sub&gt;h&lt;/sub&gt; &amp;#61; 2, e/d&lt;sub&gt;h&lt;/sub&gt; &amp;#61; 0.053, and Re &amp;#61; 4000, corresponding to which enhancement ratio of Nusselt number (Nu&lt;sub&gt;r&lt;/sub&gt;/Nu&lt;sub&gt;s&lt;/sub&gt;) and friction factor (f&lt;sub&gt;r&lt;/sub&gt;/f&lt;sub&gt;s&lt;/sub&gt;) are 2.28 and 3.14, respectively.

Microwave-assisted 3D printing of epoxy resin ink using rectangular waveguide

ABSTRACT Direct ink writing of thermosetting materials, e.g. epoxy resin, is a promising technique for the rapid and low-cost fabrication of high-strength parts with complex geometry. In this study, a microwave-assisted 3D printer using rectangular waveguide (RWG) was developed to overcome the ink's low viscosity and slow curing speed. Microwave curing and ink extrusion are synchronous to improve shape retention of ink. The critical structure parameters of the RWG applicator were determined using the multiphysics simulation to achieve optimal microwave system matching and ink heating uniformity. Experiments were conducted to investigate the processing parameters and printability. At microwave radiation temperature 95°C, the extruded ink has a significantly increased storage modulus and presents a stable and continuous cylindrical gelatinous state. Filaments can be deposited with high-quality at screw rotary speed 70 rpm and printing speed 5 mm/s. The printed sample demonstrates the excellent printability of multiple layers of extruded ink.

Research on the Fast Charging Strategy of Power Lithium-Ion Batteries Based on the High Environmental Temperature in Southeast Asia

To address the problem of excessive charging time for electric vehicles (EVs) in the high ambient temperature regions of Southeast Asia, this article proposes a rapid charging strategy based on battery state of charge (SOC) and temperature adjustment. The maximum charging capacity of the cell is exerted within different SOCs and temperature ranges. Taking a power lithium-ion battery (LIB) with a capacity of 120 Ah as the research object, a rapid charging model of the battery module was established. The battery module was cooled by means of a liquid cooling system. The combination of the fast charging strategy and the cooling strategy was employed to comprehensively analyze the restrictions of the fast charging rate imposed by the battery SOC and temperature. The results indicate that when the coolant flow rate was 12 L/min and the inlet coolant temperature was 22 °C, the liquid cooling system possessed the optimal heat exchange capacity and the lowest energy consumption. The maximum temperature (Tmax) of the battery during the charging process was 50.04 °C, and the charging time was 2634 s. To lower the Tmax of the battery during the charging process, a charging rate limit was imposed on the temperature range above 48 °C based on the original fast charging strategy. The Tmax decreased by 0.85 °C when charging with the optimized fast charging strategy.

Analysis of the optimal heat treatment temperature for AlNiCo-based semi-hard magnetic materials based on temperature-dependent yield strength prediction model

To improve the starting characteristics of permanent magnet hysteresis motors, AlNiCo-based on semi-hard magnetic materials (ASMM) is proposed. The microstructural design is carried out by combining the advantages of soft magnetic composites (SMCs) and AlNiCo8 while choosing BaTiO3 with the negative thermal expansion property to eliminate the voids. The material composition as well as the range of heat treatment temperatures are determined by the phase transition kinetics. The temperature-dependent yield strength prediction model considering stress-equivalent magnetic fields is then developed. The model establishes the quantitative relationship between yield strength, ambient temperature, magnetostriction coefficient, elastic modulus, and Poisson's ratio. The comparisons between the model and experiments are made. It can be obtained that the yield strain is related to the microstructure and morphology, and the optimum heat treatment temperature is 680°C under the condition of ensuring the highest yield strength. This method can be used to optimize the parameters of the material preparation process and provide a reference for the optimized design of high-speed and ultra-high-speed motors.

Optimisation of Sapindus Mukorossi Drying Efficiency using Response Surface Methodology

The Sapindus Mukorossi has to be pre-dried before it can be pyrolysed into bio-oil, biochar, and biogas. Traditionally, biomass is pre-dried for a full day at 105 degrees Celsius before pyrolysis. The optimum drying temperature, timing, and heating rate are essential for effective drying operation. The drying process parameters considered in the optimisation studies include temperature, duration and heating rate, and the optimisation was conducted using the response surface approach. Central Composite Design (CCD) was used to construct 20 experiment sets based on three factors (n = 3). The objective of each experiment was to observe weight reduction by applying a minimum load of 100g of Sapindus Mukorossi. The Raspberry Pi platform controlled a tailor-made 500-watt heater to adjust the temperature, rate of heating, and time. Pulse width modulation (PWM) was used to control the heating rate. The three factors and the results were generated in three-dimensional models and graphs, which finally helped to identify the best drying oven response. The optimisation method effectively resulted in a weight loss of 11.3685 g after 8 hours at a temperature of 200 °C and a heating rate of 14.15 °C/min. The CCD chooses the most efficient working parameters for the dryer to minimise operational costs. The design expert suggested a best-fitted correlation using the quadratic model with an R2 coefficient of determination of 0.9369 and a standard deviation of 0.7762.

Microstructure, Hardness, and Toughness Evolution in Nodular Cast Iron under 450°C Quenching and Tempering

This study investigated the evolution of microstructure, hardness, and toughness in nodular cast iron following quenching and tempering at 450°C. The research explored how the heat treatment process impacts these mechanical properties, to identify an optimal balance between hardness and toughness. Untreated nodular cast iron displayed a microstructure comprising ferrite, pearlite, and spheroidal graphite, resulting in moderate hardness (24.33 HRC) and toughness (0.082 J/mm²). Quenching at 850°C, followed by rapid cooling in water, induced the formation of martensite, a hard and brittle phase, which significantly increased hardness to 56.73 HRC but decreased toughness to 0.068 J/mm². Tempering at 450°C transformed the martensite into tempered martensite, reducing hardness to 41.37 HRC while improving toughness to 0.11 J/mm². These findings highlighted the importance of tempering in achieving a better balance between hardness and toughness, making the material suitable for industrial applications requiring both wear resistance and impact durability. The results offered valuable insights for optimizing heat treatment procedures to enhance the performance and durability of nodular cast iron components in various industries.

Numerical Analysis of Magnetohydrodynamic Convection in an Inclined Cavity with Three Fins and a Ternary Composition of Nanoparticles

The natural convection heat transfer of a trihybrid nanofluid comprising Fe2O3, MoS2, and CuO nanoparticles dispersed in water (Fe2O3 + MoS2 + CuO/H2O) has been investigated within a cavity exposed to a uniform magnetic field. Three cold fins were strategically positioned on the top, right, and left walls of the enclosure. The study employs numerical simulations conducted using a custom-developed FORTRAN code. The computational approach integrates the finite volume method and full multigrid acceleration to solve the coupled governing equations for continuity, momentum, energy, and entropy generation, along with the associated boundary conditions. Prior to obtaining the results, a meticulous parameterization process was undertaken to accurately capture the fluid dynamics and thermal behavior characteristic of this geometric configuration. The findings underscored the key parameters’ significant impact on the flow structure and thermal performance. The results revealed that natural convection is more dominant at high Rayleigh and low Hartmann numbers, leading to higher Nusselt numbers and stronger dependence on the tilt angle α. Moreover, the optimal heat transfer conditions were obtained for the following parameters: Ha = 25, α = 45°, ϕ = 6%, and Ra = 106 with a rate of 4.985. This study offers valuable insights into achieving a balance between these competing factors by determining the optimal conditions for maximizing heat transfer while minimizing entropy generation. The findings contribute to enhancing the design of thermal systems that utilize magnetic nanofluids for efficient heat dissipation, making the research particularly relevant to advanced cooling technologies and compact thermal management solutions.