Preset Temperature Research Articles

A coupling method for rapid, continuous and extremely wide-temperature measurement of total hemispherical emissivity and conversion efficiency of the kinetic energy of an electron beam to the thermal energy of a material based on a scanning electron beam

Precise measurements of a material's total hemispherical emissivity and conversion efficiency of the Kinetic energy of an Electron beam to the Thermal energy of a Material (KETM) are crucial for the advancement of new materials and electron beam applications. We propose a coupling method for the rapid and continuous measurements of the above parameters across an extremely broad temperature range, the basic idea of which is that a thin plate sample is uniformly heated to a high-temperature state by a scanning electron beam and naturally cooled, and equations of the transient heat transfer process in the cooling section and the heating section are solved separately based on the assumption of the lumped heat capacity, and the above parameters varying with temperature are obtained in turn. The characterization experiments of the wire-drawn and polished 304 stainless steel are carried out. The emissivities of two surface states increase monotonically in the ranges of [0.17(400K), 0.26(954K)] and [0.12(400K), 0.20(983K)], respectively, aligning well with trends and values reported in the literature. Oxidation on both surfaces worsens as the preset temperature rises, resulting in a corresponding increase in the emissivity. Considering the impact of oxidation on emissivity, KETM is calculated in various regions within the considered temperature ranges. The results indicate a slight variation around 0.819 in KETMs of wire-drawn and polished 304 stainless steel within the temperature range of 400∼1000 K, aligning well with the value reported in the literature. This efficient measurement method can provide potential support for the application of the above two parameters.

Control of Thermal Uniformity in Microwave Heating Process by BPNN and Adaptive Particle Swarm Optimization

As China advances its green economy, innovative methods are being employed to enhance energy optimization and conservation within energy-intensive industries. Among these methods, microwave heating stands out due to its superior heating efficiency and lack of pollution. Nonetheless, uniform heating remains a challenge because the microwave absorption capacity of the heated medium varies with changes in heating time and temperature. To address this issue, an Adaptive Particle Swarm Optimization (APSO) neural network microwave system based on the Back Propagation Neural Network (BPNN) is proposed. This system leverages the fundamental principles of Particle Swarm Optimization (PSO), categorizing particle swarms into three types and iterating them through distinct processes to achieve optimal results. An APSO controller is designed based on system identification, adjusting the controller parameters according to the error between the real-time system output and the identification model. The feedback error is used as the fitness function in the PSO algorithm, continuously adjusting the weights and thresholds of the neural network. This intelligent control approach optimizes the microwave oven's input power to minimize the error between the actual temperature output and the identified temperature. The APSO controller is designed based on system identification, with the intelligently controlled microwave heating system adjusting its input power to minimize the error between the identified and actual temperature outputs. Unlike traditional Proportional Integral Differential (PID) and BPNN controllers, this approach calculates the output of the identified model and the error of the actual model, feeding this information back to the controller. The feedback error serves as the fitness function in the PSO algorithm, enabling continuous adjustment of the network's weights and thresholds to regulate the microwave equipment's output power, thereby ensuring the output temperature closely follows the preset temperature curve. Experimental results demonstrate that the actual output value of the system closely aligns with the original preset temperature curve, with a root mean square error of only 0.74. This designed identification and control system effectively achieves the desired outcome.

Multi-Indicator Assessment of a Thermal Insulation Investment, Taking into Account the Pre-Set Temperature

The article proposes indicators to evaluate a thermal insulation investment in a building, such as net present value (NPV), profitability index, discounted payback period, and ecological cost efficiency. Economic and ecological aspects were taken into account. Life Cycle Assessment (LCA) was used in the ecological analysis. The following heat sources in the building were considered: condensing gas boiler and heat pump. The developed indicators also depend on the pre-set temperature in residential premises. A methodology to determine the optimum thermal insulation thickness for both economic and ecological reasons was also proposed. A case study was analyzed, and a reference building, typical for Polish construction conditions, was used for research. Various solutions were suggested regarding the type of thermal insulation material and heat sources. The values of the indicators were determined for the proposed variants and for the economically and ecologically optimum thermal insulation thicknesses. Based on the conducted research, it was found that air temperatures maintained in the rooms of the building undergoing thermal modernization should be taken into account in the energy audit. The energy demand of the building for a room temperature of 26 °C is higher by 61% compared to the demand for the same building at the design temperature (20 °C). The innovation in the proposed approach to the economic and ecological assessment of a building is the combination of a wide range of temperatures potentially maintained in living spaces with ecological cost-effectiveness.

Numerical and experimental study of directional annealing to prepare columnar grains of TiAl alloy

Directional annealing (DA) is a novel technique to prepare colunmar grains or single crystal in TiAl alloys without melt contamination. Both numerical simulation and experiments were conducted to investigate the directional annealing (DA) of a Ti48Al alloy in this paper. The temperature distribution of the TiAl rod under different DA parameters were calculated and discussed by Finite Element (FE) method. The results showed that the temperature field was significantly influenced by hot zone temperature, moving rate of induction coil, rod diameter and cooling condition. Once induction heating started, the temperature of Ti48Al rod rose rapidly and reached a steady state after about 400 s. The effective heat area (single phase zone) enlarged with the increase of preset temperature. With the decreasing movement rate of induction coil, the α/α+γ interface became more planar, and this rule also applied to the effect of the rod diameter on α/α+γ interface. Under the guidance of calculation results, optimized parameters were proposed to directionally annealing Ti48Al alloy. Rods with a diameter of 8 mm were induction-heated under the hot zone temperatures of 1673 K and 1693 K correspondingly. In the range of α single phase, the transformation of γ→α phase occurred completely and α grains directionally coarsened with the movement of hot zone. In this way, columnar grains in Ti48Al alloy were successfully formed in a solid state.

Viscoelasticity, stiffness gradient and their effects on adhesion of an epoxy shape memory polymer

The shape memory polymer based adhesives have demonstrated excellent programmable switchable adhesion, in which the material properties play an important role. Here, the viscoelasticity, stiffness gradient, and their effects on adhesion of an epoxy shape memory polymer (ESMP) were studied. The ESMP sample and polydimethylsiloxane control sample were fabricated firstly by mold casting and curing techniques. The sample was fixed on an electric heating plate with double-sided tape to conduct the adhesion measurements against a hemispherical glass indenter under different temperature and displacement conditions by using an adhesion tester and the temperature measurements on the double-sided tape and ESMP sample surfaces by using a digital thermodetector. Based on the measured force–displacement–time data, the hysteresis behavior and internal dissipation were evaluated; the peak force relaxation was studied; the reduced modulus was calculated and the stiffness gradient features were evaluated. The results show that the ESMP sample exhibits strong viscoelasticity and significantly enhanced adhesion that strongly depends on the compressive displacement in the glass-rubber transition zone near it is glass transition temperature ( Tg ), while weaker viscoelasticity and lower adhesion in the soft rubbery state. The reduced modulus of the ESMP sample obviously decreases with the increasing compressive displacement at a preset temperature below 70 °C. It is found that there exists a linear relation between the pull-off force, effective work of adhesion, reduced modulus, and contact area. This study helps deeply understand the material properties and adhesion mechanism of the ESMP, which can guide the design of switchable adhesives.

Morphometric analysis for determination of larval instars in Dermestes frischii Kugelann and Dermestes undulatus Brahm (Coleoptera: Dermestidae).

Dermestes frischii Kugelann, 1792 and Dermestes undulatus Brahm, 1790 are the most abundant species worldwide at outdoor or indoor crime scenes during the dry and skeletal stages of decomposition. The attribution of larval age in these beetles is problematic due to the variable number of instars, which is influenced by environmental factors. In this study, a morphometric approach was used to look for potential morphological features as evidence of larval stages. Breeding and monitoring were performed for both species in an incubator with a preset temperature of 28°C ± 0.5 without a photoperiod. Morphometric measurements were made on 10 larvae per instar for each species using length, width, and thickness parameters. Linear discriminant analysis was then used to generate decision boundaries that clearly separated larval stages. The cross-validation procedure demonstrated that the morphometric approach successfully discriminated adjacent larval stages in both species with high values of sensitivity and specificity. This less-invasive approach could improve the ability to estimate minPMI in forensic studies of Dermestidae beetles. Future studies may extend this approach to other species and establish good practices for collecting and storing specimens for morphometric analysis.

Industrial design of 3D printing technology combined with assisted medical service robots

AbstractWith the continuous development and maturation of the era of intelligent manufacturing, there is a perpetual emergence of new information technology, control technology, and material technology, which are constantly accelerating 3D printing technology to advance to an unprecedented level. To achieve the safety perception interaction ability of auxiliary medical service robots, this study develops a direct write hybrid 3D printing auxiliary medical service robot system, enabling it to achieve temperature sensing function. Moreover, combined with linear interpolation algorithms, 3D printing technology has been improved to achieve improvement of system control accuracy. The results indicate that the apparent viscosity of the printing material Ag‐TPU is still greater than 2000 Pa s at a rate of 87 s−1. The change in resistance during 20% stretching is within 1.2 Ω, and the change is around 3 Ω during 30% stretching. When the preset temperature is 39.2°C, the absolute deviation is the smallest, about 0.03. When the preset temperature is 41.7°C, the maximum value is approximately 0.17. The absolute error of real‐time temperature collection for auxiliary medical service robots is less than 0.2°C at temperatures ranging from 38 to 42°C. Over the past 30 days of overall operation, the system has had 970 users, 3270 interactions, and 99.4% availability. This system improves the perception and interaction ability of auxiliary medical service robots, which has certain practical potential in the field of medical services.

Simulation of a Solar Domestic Water Heating System with Different Collector Efficiences and Different Volumen Storage Tanks.

This paper shows the modeling and dynamic simulation, of a domestic solar water heating installation. The results of simulations performed on an annual basis for a solar system, operated in Santander (Spain), which provides hot water for a family (four persons) are presented. The installation consists in a solar flat collector, a water storage tank, a source of auxiliary energy, and a device for blending water. The mathematical model is used to evaluate the annual variation of the solar fraction respect to the volume of the storage tank, demand hot water temperature required, difference of this temperature and preset storage tank water temperature, and consumption profile of the domestic hot water demand. The results for a number of designs with different storage tank volumes, show that the systems with greater volume yield higher solar fraction values. However, when a larger storage tank volume is used, the solar fraction is less sensitive to a variation of these operation parameters. The results of this simulation may be used to design a solar collector system.

Magnetic properties of microwave-processed ferromagnetic La2CoMnO6

We synthesized ferromagnetic La2CoMnO6 by irradiating a stoichiometric mixture of oxide powder with microwave (MW) of frequency 2.45 GHz and studied the impact of microwave power (P) on its structural and magnetic properties. The MW power (P) was varied from 1000 to 1600 W at a pre-set sintering temperature of 1200 °C and a dwelling time of 20 min. The ferromagnetic transition temperature and saturation magnetization depend on P. The highest saturation magnetization value of 5.54 μB/f.u. was realized in the sample irradiated with P = 1400 W which is closer to the theoretical value of 6 μB/f.u. for spin-only contributions from Co2+ (S = 3/2) and Mn4+ (S = 3/2). The observed results can be attributed to varying degrees of B-site ordering of Co2+ and Mn4+ ion with the MW power, however, caution has to be taken to ensure that the sample is maintained at a specified temperature for the desired dwelling time. Our results indicate that varying the microwave power at a fixed sintering temperature provides a different approach for manipulating saturation magnetization and Curie temperature.

Improving a Fuel Cell System’s Thermal Management by Optimizing Thermal Control with the Particle Swarm Optimization Algorithm and an Artificial Neural Network

The thermal management of proton exchange membrane fuel cell systems plays a significant role in a stack’s lifetime, performance, and reliability. However, it is challenging to manage the thermal system precisely due to the multiple coupling relationships between the stack’s components, its operating environment, and its thermal management system. In addition, temperature hysteresis (temporal inconsistency of temperature with electrochemical reactions and fluid mechanics) imposes more difficulties on thermal control. We aim to develop an effective thermal control model for the fuel cell system to improve the temperature regulation accuracy and response speed and thus achieve highly stable temperature control. A dynamic mechanistic model is first developed based on the physical processes of the stack and its thermal management system. The model is then validated through experiments. Based on this dynamic mechanistic model, a control model is proposed for stack thermal management with the particle swarm optimization algorithm and an artificial neural network. It is applied and compared with the traditional PID algorithm. The simulation results indicate that the regulation time of the coolant inlet temperature as the current changes is reduced by more than 74%, and the overshoot is reduced by more than 50%. Therefore, the control model can enhance the dynamic response capability and temperature control precision under complex operating conditions with constantly changing load current and preset stack temperature, ensuring the temperature’s stability and thus improving the fuel cell system’s reliability and durability.

Continuous flowing technology for efficient and stable scale‐up production of Pt nanoparticles catalysts in PEMFC

A stable scale-up production strategy is necessary to propel high-performance Pt nanoparticles (NPs) catalysts from academic research to industrial applications. Conventional batch-type reactors scale up the production of Pt NPs catalysts by expanding the volume of the reaction vessel, which induces insufficient reaction control due to the limited heat transfer capacity. It can lead to severe agglomeration of Pt NPs and prevent the original high catalytic activity. Here, the continuous flow technology with efficient heat transfer was demonstrated to possess excellent properties of efficient and stable reaction control, which can effectively avoid agglomeration and stably produce Pt NPs catalysts with Pt NPs of uniform size and homogeneous dispersion on carbon supports at various production scales. The results show that the continuous flow technology enables the reaction slurry to reach the equilibrium temperature with a tiny difference (<1 °C) from the preset temperature within 1 min, reducing the reaction time from 4 h in the batch-type reactor to 10 min. The Pt NPs catalyst synthesized by it achieved a performance of 1.32 W cm−2 at 0.6 V, 1.4 times that of the batch-type reactor. It is an ideal solution to promote the rapid industrial application of high-performance Pt NPs catalysts that conduct laboratory synthesis studies of small amounts by the efficient and convenient continuous flow reactor and then use the same continuous flow reactor to perform efficient and stable scale-up production.

Performance Analysis of Hydrogen Production for a Solid Oxide Fuel Cell System Using a Biogas Dry Reforming Membrane Reactor with Ni and Ni/Cr Catalysts

The present study aims to analyze the performance characteristics of the biogas dry reforming process conducted in a membrane reactor using Ni/Cr catalysts and to compare these characteristics with those obtained using pure Ni catalysts. The effect of the pre-set reaction temperature, the molar ratio of CH4:CO2 and the pressure difference between the reaction chamber and the sweep chamber on the characteristics of biogas dry reforming is analyzed. In the present work, the molar ratio of the supplied CH4:CO2 is varied to 1.5:1, 1:1 and 1:1.5. In this case, CH4:CO2 = 1.5:1 simulates a biogas. The pressure difference between the reaction chamber and the sweep chamber is varied to 0 MPa, 0.010 MPa and 0.020 MPa. The reaction temperature is changed to 400 °C, 500 °C and 600 °C. It is revealed that the highest concentration of H2 is achieved using a Ni/Cr catalyst when the molar ratio of CH4:CO2 is 1.5:1 at the differential pressure of 0.010 MPa and the reaction temperature of 600 °C. Under this condition, the H2 yield, H2 selectivity and thermal efficiency are 12.8%, 17.5% and 174%, respectively. The concentration of the H2 produced using a Ni/Cr catalyst is larger than that produced using a Ni catalyst regardless of the pre-set reaction temperature, the molar ratio of CH4:CO2 and the differential pressure.

Design and Development of a Model Smart Storage System

Food security has become a global major problem, due to the rapid increase in population growth. This has necessity the development of an effective agricultural products’ storage system, to alleviate the problem of food wastage. This study was embarked upon to develop a prototype of universal smart storage system for farm products, by using the internet of thing (IoT). The storage structure consists of four principal constituents which were; the power source, storage chamber, central processing system, and peripheral component interconnect (PCI) heater and PCI fan. The developed model was tested at a pre-set temperature and relative humidity of 32C and 62% RH respectively. The results revealed that the developed system had an efficiency of 85%. Though, the smart model had a failure rate of 15%, this smart prototype is a major breakthrough in the production of automated storage system for agricultural products.

Thermal Performance of a Mechanical Thermostat for Charging an Energy Storage System

Thermal energy storage (TES) systems enhance the use of solar energy for cooking by matching the energy demand to its supply. Useful energy is extracted from TES systems that are thermally stratified and this is enhanced when charged at an averagely constant-temperature. This paper presents an experimental analysis of a mechanical-thermostat used to control the charging of an oil based TES system. The thermostat consisted of a slider-valve, an expansion-system acting both as a thermal-sensor and actuator, and an adjusting-knob for setting the charging temperature. Oil from a cold-oil reservoir flows by gravity into a heating-chamber when a manual valve is opened. In the heating-chamber, the oil is heated causing the oil to expand triggering the opening of the slider-valve at a preset temperature. This allows the hot-oil to flow into the TES system at the set temperature. The thermostat was demonstrated for charging a TES system at preset temperatures of 116 °C, 150 °C, 200 °C and 230 °C. The volume of hot-oil delivered into a TES tank decreased with increasing charging temperature. The observed temperature variations were minimized by reducing the oil flow-rate using a valve hence achieving a fairly stable charging temperature.

Diffusion and Interdiffusion Study at Al- and O-Terminated Al2O3/AlSi12 Interface Using Molecular Dynamics Simulations.

The equivalent characteristics of the materials' interfaces are known to impact the overall mechanical properties of ceramic-metal composites significantly. One technological method that has been suggested is raising the temperature of the liquid metal to improve the weak wettability of ceramic particles with liquid metals. Therefore, as the first step, it is necessary to produce the diffusion zone at the interface by heating the system and maintaining it at a preset temperature to develop the cohesive zone model of the interface using mode I and mode II fracture tests. This study uses the molecular dynamics method to study the interdiffusion at the interface of α-Al2O3/AlSi12. The hexagonal crystal structure of aluminum oxide with the Al- and O-terminated interfaces with AlSi12 are considered. A single diffusion couple is used for each system to determine the average main and cross ternary interdiffusion coefficients. In addition, the effect of temperature and the termination type on the interdiffusion coefficients is examined. The results demonstrate that the thickness of the interdiffusion zone is proportional to the annealing temperature and time, and Al- and O-terminated interfaces exhibit similar interdiffusion properties.

The In Situ Optimization of Spinterface in Polymer Spin Valve by Electronic Phase Separated Oxides.

Tailoring the interface between organic semiconductor (OSC) and ferromagnetic (FM) electrodes, that is, the spinterface, offers a promising way to manipulate and optimize the magnetoresistance (MR) ratio of the organic spin valve (OSV) devices. However, the non-destructive in situ regulation method of spinterface is seldom reported, limiting its theoretical research and further application in organic spintronics. (La2/3 Pr1/3 )5/8 Ca3/8 MnO3 (LPCMO), a recently developed FM material, exhibits a strong electronic phase separation (EPS) property, and can be employed as an effective in situ spinterface adjuster. Herein, we fabricated a LPCMO-based polymer spin valve with a vertical configuration of LPCMO/poly(3-hexylthiophene-2,5-diyl) (P3HT)/Co, and emphasized the important role of LPCMO/P3HT spinterface in MR regulation. A unique competitive spin-scattering mechanism generated by the EPS characteristics of LPCMO inside the polymer spin valve was discovered by abstracting the anomalous non-monotonic MR value as a function of pre-set magnetic field (Bpre ) and temperature (T). Particularly, a record-high MR ratio of 93% was achieved in polymer spin valves under optimal conditions. These findings highlight the importance of interdisciplinary research between organic spintronics and EPS oxides and offer a novel scenario for multi-level storage via spinterface manipulation.

Effect of Near-Liquidus Squeeze Casting Pressure on Microstructure and Mechanical Property of AZ91D Alloy Differential Support.

In this study, near-liquidus squeeze casting AZ91D alloy was used to prepare differential support, and the microstructure and mechanical behavior under different applied pressure were investigated. Under the preset temperature, speed, and other process parameters, the effect of applied pressure on the microstructure and properties of formed parts was analyzed, and relevant mechanism was also discussed. The results showed that the ultimate tensile strength (UTS) and elongation (EL) of differential support can be improved by controlling real-time precision of the forming pressure. The dislocation density in the primary phase increased obviously with the pressure increasing from 80 MPa to 170 MPa, and even tangles appeared. When the applied pressure increased from 80 MPa to 140 MPa, the α-Mg grains were gradually refined, and the microstructure changed from rosette to globular shape. With increasing the applied pressure to 170 MPa, the grain could not be further refined. Similarly, its UTS and EL gradually increased with the applied pressure increasing from 80 MPa to 140 MPa. With increasing to 170 MPa, the UTS tended to be constant, but the EL gradually decreased. In other words, the UTS (229.2 MPa) and EL (3.43%) of the alloy reached the maximum when the applied pressure was 140 MPa, and the comprehensive mechanical properties were the best.

Economic and Ecological Optimization of Thermal Insulation Depending on the Pre-Set Temperature in a Dwelling

Improvement of the energy efficiency of buildings contributes to energy savings. It is obvious that thermal modernization of a building reduces the demand for energy needed to heat it. The energy demand itself also depends significantly on the temperature maintained inside the building. The article proposes a methodology for determining the economic and ecological benefits of thermal insulation of a building and the optimal thickness of thermal insulation depending on the pre-set temperature. The analysis includes various types of heat sources and materials used for thermal insulation. A range of pre-set air temperature values in residential premises from 17 °C to 26 °C was analysed. Determining the optimal thickness of the external walls, in accordance with the preferences of building users, even at the level of designing the thermal insulation of the building, is of significant importance for economic and ecological benefits. The optimum thickness of thermal insulation in the case of the ecological assessment was much higher in each variant than in the case of the economic assessment.

Experimental investigation of an image-based method for determining the combustion temperature of aluminum particles

Aluminum is characterised by its high calorific value, stable performance, and abundant reserves. It is a commonly used additive in solid propellants that are widely used in aerospace and underwater propulsion applications. As aluminum is a key component of these solid propellants, combustion temperature measurement of aluminum particles is crucial in investigating their combustion characteristics. This paper presents a method to determine the combustion temperature of aluminum particles in solid propellants. A combination of radiation imaging and Monte Carlo probability simulation is applied in the proposed method. Further, a numerical model is established to determine the surface temperature of aluminum particles. The method is validated through numerical simulation considering a target with a pre-set temperature distribution, as well as a practical implementation in solid-propellant combustion experiments. Results of the experimental analysis establish the reliability of the proposed method and also demonstrate the method's ease of operation, good practicability, and potential for future application.

Operability evaluation of electrical wires and cables subjected to simultaneous fire and current loadings

Introduction. Intumescent coatings are used as a means of protection from heat flows, and their mission is to preserve the operability of wires and cables under fire conditions coupled with simultaneous current loading. However, the effect of insulation destruction on the operability of cables has not been studied for the case of a real fire regime.Goals and objectives. The purpose of the article is to evaluate the experimental operability of electrical wires and cables subjected to simultaneous effects of fire and current loadings.To achieve this purpose, an experimental testing unit was applied to conduct the experimental testing of wires and cables manufactured by various producers. At the same time, the temperature effect of the heated environment on electrical parameters of wires and cables, such as resistivity, inductance and capacitance, was evaluated.Theoretical background. In real fire conditions, dependence of indoor temperature, affecting the heating of cable insulation, differs essentially from the same dependencies in cases of various standard fire conditions. Therefore, the insulation destruction process may occur before the coating intumescence starts.Results and discussion. An experimental testing unit has been developed. This unit allows for the gradual cable heating with a pre-set temperature measurement interval and cable electrical characteristics. Dependencies of resistivity, inductance and capacitance of standard electrical cables on the temperature of the air surrounding the cable are obtained. It’s been discovered that the gradual heating of an electrical conductor or cable eventually leads to a short circuit between its conductive cores and further electric current transmission in electrical wires and cables. It is shown that phases and amplitudes of an input electrical signal can drastically change before the short circuit.Сonclusions. The simultaneous effect of fire and current loadings on standard electrical wires and cables causes a short circuit in the temperature range, in which no intumescence of flame retardant coatings is initiated on the insulation surface. Therefore, these coatings can ineffectively maintain the operability of electrical wires and cables.