Air-cooling Process Research Articles

Air-cooling process modelling for cord steel based on fusion approach of mechanism and artificial neural network

In this study, a modelling approach is introduced that fuses the mechanistic model with an artificial neural network (ANN) during the cord steel manufacturing. This involves replacing certain mechanistic calculations with ANN representations, optimizing mechanistic parameters through ANN techniques, and implanting mechanistic equations into the ANN framework to achieve more accurate and efficient calculations of the cooling process. The mechanistic parameters come from the models including Natural Convection Heat Transfer, Forced Convection Heat Transfer, Radiation Heat Transfer and Phase Transition during the air-cooling process. The model demonstrated an average error of 8.6 °C and 5.4 °C, compared to measurement values from two temperature sensors on the air-cooling line, and an average error of 3.3 °C relative to manually obtained temperature.

Numerical simulation for heat transfer behavior of copper slag ladle under air-cooling mechanism

Copper slag ladle cooling process is divided into two stages: air-cooling and water-cooling, is one of the important processes in copper production process from copper slag flotation recovery of valuable metals. This study investigates the transient heat transfer behavior of copper slag ladle during air-cooling mechanism based on the finite-volume method. The innovative aspect of this research lies in development of a 1:1 scale 3D model of slag ladle based on industrial-scale dimensions, obtaining the relevant thermophysical parameters of copper slag by experiment, and validating simulation results against actual industrial production data. The results of study show that: (i) The temperature distribution of copper slag within slag ladle exhibits a “concentric circle” pattern with the formation of a “liquid core” zone, indicating that the temperature is significantly higher in central region compared to periphery, revealing a notable temperature gradient during the air-cooling process; (ii) The heat flux is most concentrated in the central region of slag ladle, suggesting that the heat transfer intensity is the greatest in this area, the temperature variation of copper slag in proximity to this region is the most pronounced; (iii) The cooling path of copper slag proceeds from outer layers to inner layers, with the cooling rate decreasing from fast to slow, reflecting the temperature change trend of copper slag during air-cooling, which transitions from rapid to gradual cooling. This study provides new perspectives and data support for exploring air-cooling process of copper slag ladle and contributes to the further advancement of this field.

Study on the control of post-roll bending deformation and residual stress in hot-rolled L-beam based on rapid cooling

The bending deformation problem and internal residual stress of hot-rolled L-beams affect the quality and subsequent use performance of L-beams. In this paper, the computational model of the L-beam air-cooling process is established by using ABAQUS finite element software, which reveals the reasons for three times deformation of the L-beam from the perspectives of phase change expansion and metal cooling contraction. In order to control the deformation and residual stress of the L-beam, four experimental schemes were determined with the cooling method, water pressure, and the opening and closing state of the cooling unit of the cooler as variables. The temperature distribution, deformation before straightening, warping deformation after cutting, and magnetic field distribution curves of L-beams before and after rapid cooling under different experimental schemes were examined, and the microstructure and properties of L-beams were examined and the results were analyzed. The results show that the cooling uniformity of the L-beam can be improved by rapid cooling, which can effectively reduce the amount of bending per meter of the L-beam before straightening, the amount of warping deformation after cutting, and reduce the level of residual stress inside the L-beam, and at the same time can refine the microstructure and improve the properties. In this study, the amount of bending per meter and warpage deformation after cutting of L-beams were reduced by up to 67.3% and 85.7%, respectively, and the maximum value of the magnetic field gradient associated with the stresses in the L-beams was reduced by up to 80.2%.

Temperature distribution analysis and mechanical property prediction of wire loops in the Stelmor air-cooling system

During the Stelmor air-cooling process, the temperature distribution has a significant impact on the wire loops' final mechanical properties. The temperature distribution during air-cooling process is accurately solved by establishing three-dimensional model and Computational Fluid Dynamics (CFD) simulation. It is also found that the heat transfer coefficient on the cross section of the wire loop is very different, with a difference of 70–100 Wm−2K−1. The average value of the surface heat transfer coefficient of the wire loops section is used to replace the surface heat transfer coefficient of the wire loops, which improves the temperature distribution calculation accuracy, which is not considered by previous scholars. The finite difference method is used to calculate the mathematical model of the temperature distribution during the Stelmor air-cooling process. It is found that the maximum temperature difference of the wire during the cooling process is 90–110 K. The prediction model of mechanical property of wire after air-cooling was established, and distribution of mechanical property of the wire loops was obtained, and the reason for the uneven distribution of mechanical property of the wire loops was found.

The Effect of Refined Coherent Grain Boundaries on High-Temperature Oxidation Behavior of TiAl-Based Alloys through Cyclic Heat Treatment

The grain size of the full lamellae TiAl-based alloy changes from ~400 μm to ~40 μm through the precipitation of metastable structures by cyclic heat treatment. Based on this, two kinds of variant selection processes—coherent metastable γ variants precipitated during the air-cooling process and αs variants precipitated during the holding at a single α phase region process—are identified to promote the formation of refined Type I and Type II coherent grain boundaries. The oxidation tests at 1000 °C for 100 h show that the formation of refined coherent grain boundaries can greatly improve oxidation resistance by inducing the continuous multi-layer protective barrier consisting of (Ti, (Nb, Ta))O2, TiN, and Al(Nb,Ta)2. This protective barrier inhibits the inward diffusion of oxygen and nitrogen.

Uncovering Microstructure–Property Relationship in Ni-Alloyed Fe–Mn–Al–C Low-Density Steel Treated by Hot-Rolling and Air-Cooling Process

Uncovering Microstructure–Property Relationship in Ni-Alloyed Fe–Mn–Al–C Low-Density Steel Treated by Hot-Rolling and Air-Cooling Process

Statistical Analysis of the Air-Cooling Process in a Cowshed

During the operation of the cooling system, a large array of temperature and humidity values was obtained inside and outside the cowshed. On the basis of the obtained data set, mathematical models of temperature, humidity and temperature–humidity indices were developed. The modelled values were relevant to the actual values. The mathematical models were built on the basis of regression analysis of the data set. The data set was obtained as a result of the observations of temperature and relative humidity on one of the farms in Lithuania in semi-insulated box-type cowshed for 244 places in the summer. It was established that the efficiency of the air-cooling system is higher at a higher temperature and lower relative humidity of the air entering the cowshed. Lower humidity values contribute to a more intense decrease in the temperature–humidity index during the operation of the cooling system. The presented mathematical models are useful tools for decision making regarding the choice of cooling system operation models, as they allow one to evaluate the cooling efficiency, taking into account the influence of external factors.

Model Establishment of Chip Air Cooling Process and Its Proportional Integral Differential Tuning

Abstract Chip junction temperature is a key factor affecting the normal operation of the chip. The development of integrated circuit technology brings about high integration and low cost, but it also puts forward higher requirements for the cooling system. This paper focuses on the air cooling of the chip, builds a hardware test platform based on MCS-52, the general name of the intel series microcontroller unit, and sets up a mathematical model of the air cooling process of the chip on the matlab platform based on the principle of energy conservation, heat transfer theory and finite element method. By proposing the equivalent convective heat transfer coefficient, the thermal resistance of the system can be well estimated. This model can easily realize the joint simulation of chip, heat radiator, and control strategy, which overcomes the disadvantage that traditional finite element simulation software are difficult to combine with control strategy. In addition, based on the model, the proportional integral differential (PID) control parameters are automatically optimized, achieving excellent temperature control effect, and proving the feasibility of optimizing the control parameters through the model.

Temperature Modeling of AZ31B Alloy Plate during open-Roller Conveying Process Considering Air-Cooling Characteristics

In the process of open-roller conveying, magnesium alloy plates easily produce temperature drops and uneven temperatures. Ignoring the heat dissipation caused by the contact between the plate and the roller table, the process can be described as a process of air cooling. The present study aimed to investigate the temperature distribution and evolution of a magnesium alloy plate during the process. The air-cooling process of the AZ31B magnesium alloy plate was investigated and analyzed in detail under different initial temperatures and plate thicknesses, with a specific focus on the temperature distribution along both the width and thickness directions. The results show that the temperature-difference curves between the end face and the center under different air-cooling conditions appeared to have four stages: rapid increase, slow increase, basic stable and slow decline. To facilitate the establishment of the temperature model, the whole air-cooling process was approximately divided into two independent one-dimensional heat-conduction processes in the thickness direction and the width direction. Subsequently, one-dimensional steady-state heat-conduction models were developed in various directions, based on the fundamental principles of heat transfer and assuming that the adjacent temperature-drop layer satisfied the quadratic function distribution. Through the superposition of cooling with time in two directions, the temperature evolution at different positions in the process of air cooling can be solved accurately.

Dry sliding wear behaviour of hot-rolled air-cooled medium manganese martensitic steel

The microstructure, mechanical properties and dry sliding wear behaviour of hot-rolled air-cooled medium manganese martensitic steel at different finish rolling temperatures (FRT) were investigated. The fully martensitic structure with precipitation of acicular carbides in the matrix was obtained in the air-cooled process after hot rolling. With the decrease of FRT, the mechanical properties and sliding wear resistance of experimental steels were significantly improved. The worn surface morphology was mainly furrows, and the wear mechanism was micro-cutting. Both the width and depth of the furrows increased with the increasing hardness of the experimental steels. The mass loss rates of FRT-700, FRT-900 and Hardox450 samples were 4.53 × 10-4 g/m, 4.82 × 10-4 g/m and 5.14 × 10-4 g/m, respectively.

Economic cost analysis of air-cooling process using different numbers of Peltier modules; Experimental case study

Generally speaking, a Peltier module obtains a high value of COP only for a small range of applied DC voltage. Indeed, increment of DC voltage sharply reduces its COP. Hence, to get a high total COP for a large-scale commercial Peltier air cooler (for example input power of 1000 W) each individual Peltier module should work with a small input DC voltage. This means, a greater number of Peltier modules should be employed in a real cooler to reduce the allocate DC voltage for any individual Peltier module. However, this means higher capital, maintenance, operating and maybe final cooling cost. Hence, a size related cost economic analysis is required for cooling process using Peltier module which is experimentally presented in this research. Three Peltier air coolers with different sizes (but in the same range of total input power) are investigated from efficiency and economic cost viewpoints. Findings show that despite the higher capital and maintenance cost for case “c” (6 TEM), it still provides cheaper cooling compared to the other cases. However, it is noted that case “b” (4 modules) provides 100% lower cooling cost compared to the case “a” (2 modules) while case “c” (6 modules) provides only 35% lower cooling cost compared to the case “b”. This means, although increasing module number enhances the total COP of the cooler (for a given input power) and reduces the cooling cost, further increment of module number will finally augment the cooling cost of the cooler. Hence, an optimized number of modules can be selected for a large-scale cooling by simultaneous multi economic and cooling optimization. The quantitative and qualitative findings of this research can be useful for future marketing, and commercialization purposes of large-scale air-cooling process using Peltier module.

Numerical simulation and experimental investigation of bending deformation mechanism during post-rolling air cooling of AH36 L-beam

L-beam is a widely used structural steel. The study of the three-stage bending deformation mechanism of L-beam under non-uniform cooling conditions is of great significance to ensure the quality, improve the yield of steel, and reduce the stress level in the finished L-beam. However, it is difficult to investigate experimentally due to the high temperature and simultaneous changes of various influencing factors during the air-cooling process of the L-beam. Numerical simulation provides a convenient and feasible method to study the bending deformation mechanism of the L-beam. To investigate the effects of phase transformation and cooling shrinkage on the bending deformation of AH36 L-beam, a three-dimensional thermal-metallurgical-mechanical coupling model was established in this study; the microstructure distribution, hardness, strain, deformation status, and stress during the air cooling of L-beam were calculated. The results show that the microstructure distribution and deformation condition calculated by the model considering the phase transformation effect better agree with the actual situation. Considering the phase change effect is the key to improving the accuracy of the model calculation. The change of heat transfer coefficient caused by phase transformation affects the deformation tendency of the L-beam, while the transformation strain affects the amount of deformation of the L-beam. The alternating changes in the sum of the transformation strain and the cooling shrinkage strain result in a change of stress state which ultimately also results in a three-stage bending deformation of the L-beam.

Investigation of the Flow Behavior of Air-Cooling Ti-6Al-4V Alloy after Superplastic Forming

The flow behavior of Ti-6Al-4V alloy during the air-cooling process after superplastic forming (SPF) has been discussed. In high-temperature constant strain rate tensile tests, the selected temperatures were 930, 900, 800, 700, and 600 °C, and the initial strain rates were 10−2, 10−3, and 10−4/s. The optimized deformation temperatures were 800~900 °C and the strain rates were 10−4~10−3/s. Then, the evolutions of activation energy and deformation strain are also discussed, and the effects of dislocation density and deformation activation energy on flow behavior were consistent. In addition, unstable flow is mainly concentrated in the low-temperature and high strain-rate regions, and this is mainly caused by dynamic recrystallization (DRX). After the SPF process, the possibility of material damage gradually increases during the air-cooling process.

Relationship between Microstructure and Properties of 1380 MPa Grade Bainitic Rail Steel Treated by Online Bainite-Based Quenching and Partitioning Concept

According to the concept of the bainite-based quenching and partitioning (BQ&P) process, we designed the online heat treatment routes of bainitic rail steel for heavy haul railway. The new heat treatment process reduced the fraction and size of the blocky martensite/austenite (M/A) islands formed during the conventional air-cooling process. The M/A islands are coarse and undesirable for mechanical properties. A new kind of 1380 MPa grade bainitic rail steel with more uniform microstructure and better mechanical properties was produced by the online BQ&P process. We characterized the multiphase microstructures containing bainite, martensite, and retained austenite of 1380 MPa grade bainitic rail steels via optical microscope, scanning electron microscopy, transmission electron microscopy, and X-ray diffractometer. We investigated in-depth the relationship between the microstructure, retained austenite stability, and mechanical properties, particularly the resistance to wear and rolling contact fatigue, of the new 1380 MPa grade bainitic rail steels. Meanwhile, the conventional air-cooling bainitic rail steel was studied as a comparison.

Evaluation of interfacial heat transfer coefficient based on the experiment and numerical simulation in the air-cooling process

Evaluation of interfacial heat transfer coefficient based on the experiment and numerical simulation in the air-cooling process

Microstructure refinement and strengthening mechanisms of network structured TiBw/Ti6Al4V composites by TIG remelting

In order to further strengthen TiB whiskers reinforced Ti6Al4V (TiBw/Ti6Al4V) composites with a network microstructure, tungsten inert gas (TIG) remelting was performed on the composites with different reinforcement volume fractions to tune microstructure. The results showed that the size of network unit and TiB whisker reinforcement of the composites were significantly refined from 150 μm to 20 μm in diameter and 3 μm to 0.5 μm in width after remelting, respectively. Moreover, the α phase of Ti6Al4V matrix was transformed into a refined α′ phase due to the rapid air-cooling process. It is also revealed that the refinement of network microstructure was resulted from the hypoeutectic reaction of the Ti–B system. However, the network microstructure disappeared when the reinforcement volume fraction rises to 10 vol.%, and then coarse primary TiBw appeared when to 20 vol.%. After remelting, the hardnesses of 3.4 vol.%, 10 vol.%, 15 vol.% and 20 vol.% TiBw/Ti6Al4V composites were increased to HRC 36, HRC 40, HRC 43 and HRC 50 from HRC 32, HRC 37, HRC 40, HRC 47, respectively. The tensile strength at 600 °C was increased by 10%–20% while remaining the similar tensile ductility. The strengthening mechanisms can be mainly attributed to microstructure refinement and α’ martensite formation.

Particle Image Velocimetry (PIV) experiment of the buoyant flow field of a thermal chimney model designed for geothermal power plants

ABSTRACT To enhance the air-cooling process in geothermal power plants for economical utilization of the exhaust steam from expansion, a natural-draft thermal chimney design was proposed and studied here in this paper. In view of the necessity of accurate velocity field measurements which would provide further insight into the physics behind the evolving plumes above heated horizontal cylinders, Particle Image Velocimetry (PIV) was employed to experimentally investigate the buoyant flow in the thermal chimney system. Two configurations have been tested to understand the flow induced by the horizontally heated cylinders inside the thermal chimney. Firstly, flow field above a single row of cylinders was tested while they were isothermally heated to simulate of an air-cooled condenser. After that, a second row of cylindrical heaters (air-heater) was added above the first row to enhance the buoyant flow, aiming at enhancing the air side flow of the air-cooled condenser. Flow characteristics and velocity enhancement were studied for both configurations. The results show that significant flow unsteadiness occur near the cylindrical heaters because of the non-steady crossing flows between adjacent cylinders, and the unsteadiness attenuates in the downstream. The effects of cylinder row distance, surface temperature as well as downstream distance on the flow field were then analyzed. Flow velocity is increased by the air-heater as the buoyancy force is enhanced, proving the idea of flow enhancement of the thermal chimney configuration. It is also observed that the velocity fluctuation, turbulent kinetic energy and vorticity change significantly after adding the second row of heaters. The present study provides further insight into natural convection flow theory of heated cylinders for a Rayleigh number range of 1.3E4 to 2.2E4, which is fundamental for the flow enhancement designing of the proposed natural-convection-driven cooling system.

Исследование процесса воздушно-водоиспарительного охлаждения в аппаратах воздушного охлаждения

Исследование процесса воздушно-водоиспарительного охлаждения в аппаратах воздушного охлаждения

Investigation of Metal Air-Cooling Process as An Element of Thermal Processing

<p>Background: Nowadays on metal tempering and annealing its air cooling (AC) is realized inside furnace with forced coolant delivery. Scientific tools lack for metal AC study and design is substantiated. The aim of this work is to investigate technological and design furnace parameters influence on metal AC duration, as well as disclosure of metal AC heat engineering regularities. Materials and method: For study mathematical model of metal AC is used. It bases on solving the differential non-stationary heat conductivity equation in one-dimensional form for cylindrical ingots and lining. Results: For three lining design types and different technological parameters operation acceleration possibility due to lining design change was studied. It is found that with ceramic fibers on walls and roof acceleration is 31-45% and with all lining made of ceramic fiber it is 44-52% as compared with fireclay brick lining. For a furnace with hearth of fireclay bricks and ceramic fiber on the walls and roof, convective component varies from 10 to 30%; for lining completely consisting of ceramic fibers it is 10 - 25%. When using fireclay brick lining parts their inner temperature is higher than for ceramic fiber up to 50 °C. Conclusions: Significant furnace lining materials type influence on metal AC intensity is proved. Heat removal mechanism on metal AC in furnace is disclosed, by establishing heat proportion directly removed from metal by convection. It is found that radiant heat transfer between metal and fireclay brick part of lining goes less intensively than with ceramic fiber part. </p>

A method to predict early-ejected plastic part air-cooling behavior towards quality mold design and less molding cycle time

Abstract It is a common industrial practice to eject injection-molded plastic parts early, at a high temperature, and allow the parts to cool down in the air. This practice shortens the cycle time and reduces production cost. However, current commercial injection molding simulation software tools can only consider the in-mold cooling process. The simulation of the air-cooling stage after ejection is not well supported in such tools even though the air-cooling shrinkage is significant when plastic parts are ejected at high temperatures. The authors propose a Moldflow™-Ansys™ integrated FEA method to simulate the air-cooling process so that the air-cooling shrinkage can be considered at the early design stage and the quality of the part can be ensured with less molding cycle time. A real industrial case study is provided to show the procedure and its validation. The proposed method integrates Moldflow™ and Ansys™ by feeding Moldflow™ simulation results as the intermediate state data set into Ansys™ for air-cooling effect simulation. With a real testing product part ejected at a high temperature, the proposed approach shows promising predictions of the 3D warpage displacement. In this way, the cost factor of molding cycle time can be considered at the mold design stage and a cost-effective design can be developed.