Quench Temperature Research Articles

Design and operational features of an active condensation system for enhanced energy efficiency in a biomass-fired district heating plant

The study addresses the design and operational features of an active condensation (AC) system aimed at improving the energy efficiency of a 3rd generation district heating (DH) plant. Several similar biomass-utilizing plants have recently been built in the Republic of Serbia. The plant is equipped with biomass-fired boilers totaling 2 MW capacity, utilizing varying qualities of wet wood chips. The goals are: (i) to determine optimal constant and variable quench temperatures; (ii) to calculate the electricity consumption of ancillary devices and assess their impact on AC system performance; (iii) to evaluate the effect of biomass moisture variations on system size and performance; (iv) to assess the economic viability of integrating the AC system; and (v) to establish selection and design criteria for the heat pump (HP). For a given commercial HP, an optimal quench temperature exists, dependent on the minimal temperature lift required by the HP. This temperature can be calculated simply by subtracting the minimal HP lift from the lowest possible temperature that the HP can supply to a DH system at the average outdoor temperature. Consequently, an optimal variable quench temperature exists that should be adjusted to enable the HP to operate with its minimal temperature lift.

Enhanced T5 age-hardening behavior of Al–Si–Mg casting alloy with prolonged melt holding and high quench temperature

The effects of the quench temperature (cooling rate) and melt-holding time at high temperatures on the precipitation kinetics and nanostructure of the Al–Si–Mg alloy were investigated by measuring the hardness and electrical conductivity, differential scanning calorimetry, transmission electron microscopy, and atom probe tomography. The results showed that a high quenching temperature (high cooling rate) and long melt holding simultaneously increased the hardness and electrical conductivity of the Al–Si–Mg alloy. They also accelerated the overall precipitation kinetics; however, the effect was more evident when the duration of high-temperature melt holding increased. Nanostructural analysis of the peak-aged conditions revealed that the accelerated precipitation kinetics of the alloy with a high quenching temperature were primarily related to the high amount of Si solutes, which prevented the formation of coarse Si precipitates. Conversely, the high precipitation kinetics caused by longer melt-holding treatments depend on the increased amount of solutes and dissolution of clusters and could disturb the formation of strengthening β″ precipitates. These results indicate that the mechanical properties of the T5-treated Al–Si–Mg alloy can be significantly enhanced by increasing the quenching temperature and providing sufficient melt holding at high temperatures.

Quench Detection and Temperature Measurement With Fiber Optic Sensors

Quench Detection and Temperature Measurement With Fiber Optic Sensors

Role of Quenching Temperature Selection in the Improvement of the Abrasive (Al2O3) Wear Resistance of Hybrid Multi-Component Cast Irons.

In this paper, enhancing the tribological characteristics of novel cast metallic materials-hybrid multi-component cast irons-by applying a strengthening heat treatment is described. The experimental materials were the cast alloys of a nominal composition (5 wt.% W, 5 wt.% Mo, 5 wt.% V, 10 wt.% Cr, 2.5 wt.% Ti, Fe is a balance) supplemented with 0.3-1.1 wt.% C and 1.5-2.5 wt.% B (total of nine alloys). The heat treatment was oil-quenching followed by 200 °C tempering. The quench temperature (QT) varied in the range of 900-1200 °C, with a step of 50 °C (with a 2-h holding at QT). The correlation of the QT with microstructure and properties was estimated using microstructure/worn surface characterization, differential scanning calorimetry, hardness measurement, and three-body-abrasive wear testing (using Al2O3 particles). The as-cast alloys had a multi-phase structure consisting of primary and/or eutectic borocarbide M2(B,C)5, carboborides M(C,B), M7(C,B)3, M3(C,B), and the matrix (ferrite, martensite, pearlite/bainite) in different combinations and volume fractions. Generally, the increase in the quenching temperature resulted in a gradual increase in hardness (maximally to 66-67 HRC) and a decrease in the wear rate in most alloys. This was due to the change in the phase-structure state of the alloys under quenching, namely, the secondary carboboride precipitation, and replacing ferrite and pearlite/bainite with martensite. The wear rate was found to be inversely proportional to bulk hardness. The maximum wear resistance was attributed to QT = 1150-1200 °C, when the wear rate of the alloys was lowered by three to six times as compared to the as-cast state. With the QT increase, the difference in the wear rate of the alloys decreased by three times. The highest abrasive resistance was attributed to the alloys with 1.1 wt.% C, which had a 2.36-3.20 times lower wear rate as compared with that of the reference alloy (13 wt.% Cr cast iron, hardness of 66 HRC). The effects of carbon and boron on hardness and wear behavior are analyzed using the regression models developed according to the factorial design procedure. The wear mechanisms are discussed based on worn surface characterization.

Tuning pore size and density of rigid polylactic acid foams through thermally induced phase separation and optimization using response surface methodology

Rigid polylactic acid (PLA) foams fabricated via thermally induced phase separation (TIPS) utilizing a ternary solution of PLA, Tetrahydrofuran (THF), and water. The PLA gels were stabilized mechanically by the substituting of the THF/water solvent mixture with ethanol as non-solvent and subsequently vacuum dried. A comprehensive characterization of PLA foams was achieved by Scanning Electron Microscopy (SEM), X-ray Diffractometry (XRD) and Brunauer–Emmett–Teller (BET) analyses. The BET area obtained in the PLA foam is up to 18.76 m2/g. The Response Surface Methodology (RSM) was utilized to assess the impacts of four independent variables (polymer concentration, solvent composition, quench temperature, and aging time) on the pore size and density of PLA foam. The experimental findings demonstrated that the fabrication parameters could be fine-tuned to govern the morphology of the pores, comprising their size and density. The optimal values of parameters for cell size were identified by RSM to be 8.96 (wt%), 91.60 (w/w), 5.50 °C, and 3.86 h for the optimum cell size of 37.96 µm (37.78 by Genetic Algorithm). Optimum density by RSM 88.88 mgr/cm3 (88.38 mgr/cm3 by Genetic Algorithm) was obtained at 5.00 (wt%), 89.33 (w/w), 14.40 °C and 2.65 h.

Optimizing the Microstructure and Mechanical Properties of Quenching and Partitioning 12% Chromium Stainless Steel Through Nitrogen Addition and Quench Temperature Control

Optimizing the Microstructure and Mechanical Properties of Quenching and Partitioning 12% Chromium Stainless Steel Through Nitrogen Addition and Quench Temperature Control

Spray cooling of micropillared steel plates: Two-stage quenching phenomenon

Spray cooling is a crucial process of steel manufacturing, nuclear power plants and electronics thermal management. However, its precise control is challenging due to the various boiling regimes involved at different temperature levels. Transition from film boiling to nucleate boiling, namely, the onset of quench is our particular interest as it remarks the thermal history of the hot object. Based on our previous findings that quench occurs at a specific temperature defined at the droplet-surface interface we demonstrate that micropillars on steel plates can increase the quench temperature Tq . We performed water spray cooling tests with stainless-steel samples, on which various configurations of micropillars were fabricated using laser texturing. Interestingly, we observed two stages of quench for a specific sample: a drastic increase in the cooling rate at ca. 450 °C, followed by another increase at ca. 250 °C. The first cooling rate increase is attributed to the initiation of stable liquid-solid contact at the pillar tops. Eventually, water wets the entire pillars and the bottom surface, further increasing the cooling rate. Samples with higher pillars showed no film boiling regime in the experiment, implying higher quenching temperature (Tq > 600 °C). We attribute the increased apparent Tq to the narrow heat conduction path within the micropillar, resulting in a significant temperature drop at the tip which enhances liquid-solid contact.

Numerical Modeling and Simulation of the Nonisothermal Double Quench Phase Separation Process for the Production of Polymeric Membranes Using Polystyrene‐Cyclohexanol Polymer Solution

AbstractThe double quench phase separation is a simplified type of continuous cooling process that is widely seen in industrial processes for polymeric membrane formation. Uncommon quenching conditions can lead to the creation of novel membrane microstructures. This study aims to theoretically investigate the impact of nonisothermality on the morphology formation during the double‐quench thermally‐induced phase separation process. First, quench is employed during different stages of phase separation to observe the possibility of secondary morphology formation. Next, two initial quench temperatures are selected, one shallow and the other deep. The initial solution temperature and the secondary quench temperature are kept constant to inspect the impact of the initial quench temperature on the structure formation. Lastly, the results of the secondary quench are compared with and without employing the enthalpy of demixing. Results verified that the stage of phase separation, the initial and secondary quench temperatures, cooling rate, and the secondary quench composition are the most important parameters in the the nonisothermal double quench phase separation process. The morphology should be well‐developed in order for the secondary structure formation. In addition, it is shown that heat generation during demixing in the primary and secondary quenches significantly influences the secondary morphology formation.

Viologen-based supramolecular crystal gels: gelation kinetics and sensitivity to temperature.

Supramolecular crystal gels, a subset of molecular gels, are formed through the self-assembly of low molecular weight gelators into interconnecting crystalline fibers, creating a three-dimensional soft solid network. This study focuses on the formation and properties of viologen-based supramolecular crystalline gels. It aims to answer key questions about the tunability of network properties and the origin of these properties through in-depth analyses of the gelation kinetics triggered by thermal quenching. Experimental investigations, including UV-Vis absorption spectroscopy, rheology, microscopy and scattering measurements, contribute to a comprehensive and self-consistent understanding of the system kinetics. We confirm that viologen-based gelators crystallize by forming nanometer radius hollow tubes that assemble into micro to millimetric spherulites. We then show that crystallization follows the Avrami theory and is based on pre-existing nuclei. We also establish that the growth is interface-controlled, leading the hollow tubes to branch into spherulites with fractal structures. Finally, we demonstrate that the gel properties can be tuned depending on the quenching temperature. Lowering the temperature results in the formation of denser and smaller spherulites. In contrast, the gel's elasticity is not significantly affected by the quench temperature, leading us to hypothesize that the densification of spherulites occurs at the expense of connectivity between spherulites.

Ironing out the transition metal contribution to the magnetism of the n = 3 members of the homologous series Prn+1MnGe3n+1 (M = Fe, Co): Pr4Fe3Ge10 vs. Pr4Co3Ge10

The Lnn+1MnX3n+1 (Ln = lanthanide, M = transition metal, and X = tetrel) homologous series provides a platform to study collective phenomena in quantum materials. In this work, we compare the crystal growth, structure, and magnetic properties of the n = 3 members of the Prn+1MnGe3n+1 (M = Fe, Co) analogues, Pr4Fe3Ge10 (a = 4.3207 (10) Å, b = 35.523 (8) Å, c = 4.2982 (15) Å, and V = 659.7 (3) Å3) and Pr4Co3Ge10 (a = 4.3091 (12) Å, b = 35.750 (9) Å, c = 4.2807 (11) Å, and V = 659.4 (3) Å3). We determined that the ideal flux growth conditions for each compound are highly dependent on the concentration of Sn flux and quench temperature. Pr4Fe3Ge10 orders ferromagnetically at 10 K along the c-direction while Pr4Co3Ge10 orders antiferromagnetically at 16 K along the b-direction. For both compounds, we observed a magnetic moment higher than that expected for only Pr3+ ions (3.58 µB/Pr), implying that the transition metal ions contribute to magnetic ordering (3.91, 3.48, and 3.69 µB/Pr for Pr4Fe3Ge10, and 3.76, 4.04, and 3.83 µB/Pr for Pr4Co3Ge10 measured along the a-, b-, and c-directions, respectively). Moreover, the zero-field Mössbauer spectrum obtained at 4.2 K for Pr4Fe3Ge10 demonstrates that the iron sites participate in magnetic ordering.

Expanding polymeric feedstocks for powder bed fusion via rational control of liquid–liquid phase separation

AbstractPowder bed fusion (PBF) is a promising technology in polymeric additive manufacturing, whose growth is inhibited by limited material options. In this manuscript, we report the use of thermally induced phase separation (TIPS) to controllably produce polymer powders of polypropylene that are suitable for PBF. Moreover, these studies provide crucial insight into the factors that govern the final size of the produced powder, offering fundamental insight that fosters the rational control of powder fabrication for PBF. More precisely, the impact of polymer concentration, molecular weight, and quench temperature on the size of the powder is demonstrated, where the particle size increases with solution concentration, quench temperature and molecular weight. The molecular weight dependence is consistent with a decrease in polymer solubility with an increase in chain length, while the solution concentration dependence can be explained by the relative fractions of the two phases in the precipitation process of polymer solutions. Careful analysis of the temperature and solution concentration dependence of the powder verifies that droplet coalescence is the governing mechanism in the phase separation‐based particle formation process. Therefore, this fundamental understanding provides pathways to use TIPS to produce powders suitable for PBF from a broad range of polymer solutions.

The Reliability of Single-Step and Double-Step Quench and Partitioning Heat Treatments on an AISI 420A Low Carbon Martensitic Stainless Steel

The microstructural and mechanical effects of various single-step (SS) and double-step (DS) quench and partition (Q&P) heat treatments applied to an AISI 420A low carbon martensitic stainless steel (MSS) has been studied. The goal with this work is to reach a total elongation (E pct) of 12 pct and an ultimate tensile strength (UTS) above 1200/1300 MPa, but ultimately to achieve a superior strength-ductility balance in comparison to its traditional Quench and Temper (Q&T) counterpart. This is being done by retaining austenite within the steel’s martensitic matrix at room temperature (RT) using novel SS and conventional DS Q&P heat treatments. Considerable work has been done to optimize DS Q&P heat treatments, but little has been done to understand the effects of removing a subsequent heating cycle through SS Q&P heat treatments has on MSSs. With that being said, partitioning is performed at the same quench interruption temperature for the SS Q&P heat treatments, and reheated to a higher temperature for the DS Q&P heat treatments. Experimental investigations were carried out on 1 mm thick, sheet samples to increase the number of potential applications for this steel and heat treatment. The microstructure of different SS and DS Q&P heat treatments was investigated through X-ray diffraction (XRD) and transmission electron microscopy (TEM) while mechanical property investigations were carried out using tensile and fracture toughness testing. DS Q&P heat treated samples quenched to 130 °C and partitioned for industrially relevant times of 10 and 30 minutes featured the highest values in terms of total elongation, tensile strength and fracture toughness. The SS Q&P heat treatments, on the other hand, were able to achieve improved mechanical properties to its Q&T counterpart. Overall, this work opens up the possibility of increased MSS usage for reliable, thin-walled component production with improved properties through Q&P heat treatment methods. The best results achieved in this study are a UTS of 1585 MPa, E pct of 22 pct, and a fracture toughness of 77 kJ/m2. Their lower total elongation of 9.6 pct is balanced by high tensile strength of 1812 MPa, ensuring higher toughness compared to traditional Q&T samples.

Arrested spinodal decomposition of the screened symmetric restricted primitive model.

Amorphous solids, such as glasses and gels, arise as the asymptotic limit of non-equilibrium and irreversible relaxation aging processes. These amorphous solids form when the system is suddenly and deeply quenched in the dynamic arrest region. We use the non-equilibrium self-consistent generalized Langevin equation (NE-SCGLE) theory to investigate the formation of such structures via arrested spinodal decomposition in the screened symmetric restricted primitive model. We propose a direct correlation function that allows us to derive an expression for the functional derivative of the chemical potential, which serves as the necessary input in the NE-SCGLE theory. By analyzing the asymptotic localization length and the asymptotic characteristic length, we identify different classes of dynamic arrest states as a function of the density and the final quench temperature. The system features simultaneously attractive and repulsive interactions, resulting in different arrested regions in the non-equilibrium phase diagram for a given screened parameter: (i) ionic glasses, (ii) electrostatic gels, and (iii) attractive glasses. Finally, by collapsing the asymptotic effective structure factors at a typical fractal dimension of df = 3, we confirm the formation of gels slightly above the glass-gel transition in the arrested phase diagram.

Understanding Vogel-Fulcher–like equilibration times through the partial equilibration scenario

We test a post-quench Partial Equilibration Scenario (PES) of Ritort and colleagues, through Monte Carlo quench simulations, of a vector-spin model for a cubic-to-tetragonal, martensitic structural transition. We confirm the PES signature distribution of an exponential tail in heat releases, scaled in an effective search temperature that regulates energy-lowering passages between fixed-energy shells. Our simulations find that this effective temperature vanishes linearly in the deviation of the quench temperature from a divergence temperature, where passage bottlenecks in phase space segment their topology, and entropy barriers diverge. Equilibration delay times, exponential in the inverse effective temperature, are thus predicted to show singular Vogel-Fulcher behaviour, understood here as an arrest of PES heat releases to the bath, and confirmed by experimental data on martensitic alloys.

Effect of Microstructure on Mechanical Properties of Quenching & Partitioning Steel

The microstructure and mechanical properties of a low-carbon steel produced via the quenching & partitioning (Q&P) heat treatment was investigated, with particular focus on the hole expansion ratio, which is an index of the stretch-flange-formability. 0.19mass%C-1.5mass%Si-2.9mass%Mn steel was annealed at 850 ˚C, then cooled to 150~400 ˚C (QT: quench temperature), followed by holding at 400˚C for 1100 s. Yield strength and hole expansion ratio drastically increased when the QT was below the Ms (martensite start) temperature. The steel with QT of 300 ˚C exhibited not only a higher elongation, which has been well documented, but also a higher hole expansion ratio, when compared to the conventional TRIP steel with QT of 400 ˚C having equal tensile strength around 1200 MPa. The micro-void formation during deformation was suppressed in the steel with QT of 300 ˚C due to the smaller volume fraction of large blocky martensite compared to the TRIP steel. These excellent mechanical properties are attributed to its unique microstructure consisting of a certain amount of tempered martensite, lath-shaped retained austenite and bainitic ferrite, which was generated via the Q&P heat treatment.

Phase separation kinetics of binary mixture in the influence of bond disorder: sensitivity to quench temperature

ABSTRACT Morphologies in phase-separating systems can significantly influence final material properties. We present extensive Monte Carlo simulation results on segregation kinetics of critical binary mixture (-Ising system) with a fraction of bond disorder introduced regularly. The effect of various quench temperatures is studied on growth kinetics and scaling properties of evolved morphologies. The morphology changes from their usual bicontinuous isotropic patterns at zero disorder to short strips and lamellar patterns (anisotropy) with the increasing disorder at shallow quench depth. The domain evolution at lower disorder remains at a transient growth regime for deep quench; however, the lamellar pattern is observed at high disorder for the same quench depth. The scaling behavior changes significantly with quench depths at the higher fraction of disorder. Though, a tiny deviation is observed at lower disorder fractions for shallow quench depths. The length scale freezes () to finite size at the higher disorder asymptotically.

Morphology formation during the nonisothermal thermally‐induced phase separation (TIPS) process

AbstractIn high‐viscosity polymer solutions and blends, temperature variations during the quench process of the thermally‐induced phase separation (TIPS) influence the dynamics and thermodynamics of phase separation. Hence, this study aims to investigate the impact of temperature variations on the morphology formation during the TIPS process. First, the influence of temporal temperature variations on phase separation is investigated by coupling a transient heat conduction model and the Cahn–Hilliard equation, and the results are compared with the isothermal phase separation process. Next, the morphology formation during phase separation is inspected by applying quench from two opposite sides of the sample to the same and different temperatures through coupling the Fourier heat transfer equation and the Cahn–Hilliard equation. The influence of the enthalpy of demixing on the morphology formation and the competition between the heat and mass transfer is also evaluated. It is confirmed that temporal variations of temperature alone have a significant impact on the morphology formation during the TIPS process. In addition, quenching the system to the same and different temperatures both leads to anisotropic morphology formation, which is affected by the quench rate, quench temperature, solution viscosity, and enthalpy of demixing. Upon applying different quench temperatures from opposite sides, two different types of morphologies and droplet sizes were formed as a result of the difference in the cooling rates between the two sides. Employing the enthalpy of demixing during phase separation induced a shallow quench effect on the deep quench side due to the fact that the heat moved toward the lowest temperature in the system, which led to the formation of a distinctive structure.

The Effect of Quenching and Partitioning (Q&P) Process on the Structural and Mechanical Properties of AISI 4130 Steel

In this study, the effect of quenching and partitioning (Q&P) heat treatment on the structural and mechanical properties of AISI 4130 steel was investigated. The Q&P process was followed at a quench temperature of 270 oC and three different partitioning temperatures of 270, 330, and 380 oC. The phase and structural characterization of the prepared spicimens were done using X-ray diffractometer (XRD) and scanning electron microscopy (SEM), respectively. The mechanical properties of the samples were also monitored by hardness and tensile test according to ASTM E8 standard. The results showed that the tensile strength can be increased up to 1450 MPa while maintaining the elongation percentage (about 9.6%) by performing the Q&P process on the AISI 4130 steel. This strength is about 20% greater than that of obtained by the usual quench and tempering process in this steel. Optimum partitioning temperature and time for AISI 4130 steel were determined to be 330 °C and 120 minutes, respectivly. Partitioning at lower temperatures could not stabilize the austenite phase, while partitioning at higher temperatures caused the decomposition of the austenite phase and carbide precipitation.

Enhancement of quenching heat transfer performance through destabilization of vapor film

Film boiling is typically the rate-limiting process during quenching relevant to manufacturing, material processing, and vitrification. Here, we report on the effect of macroscale surface extends (fins) and microscale textures on the enhancement of quenching heat transfer performance. At a quench pool temperature of 80 °C, the pin-finned surfaces with hierarchical roughness decrease the quench duration by 4.5 times, 3.4 times, and 1.3 times compared to a plane, annular-finned, and pin-finned substrates, respectively. Annular and pin-finned surface extends influence the vapor geometry in the film boiling regime and trigger a premature collapse of the vapor film on vertical cylinders, elevating the minimum film boiling temperature. The pin fins enable higher heat transfer in the film and transition boiling regimes by disrupting the vapor film while providing a pathway for vapor escape, unlike annular fins. The hierarchical surfaces with microtextures etched on the pin fins further increase heat dissipation by offering nucleation sites. We discuss the role of surface textures on the range of temperatures that sustain the transition boiling regime during quenching.

The Effect of Conductive Heat Transfer on the Morphology Formation in Polymer Solutions Undergoing Thermally Induced Phase Separation.

Owing to the fact that heat transfer during the thermally induced phase separation process is limited, a quench rate is inevitably entailed, which leads to the existence of temporal and spatial variations in temperature. Hence, it is of great importance to take into account the nonisothermality during the phase separation process, especially in high viscosity polymer solutions. In this study, the influence of conductive heat transfer on the morphology formation during the thermally induced phase separation process was investigated theoretically in terms of quench depth, boundary conditions, and enthalpy of demixing to elucidate the interaction between temperature and concentration through incorporating the nonlinear Cahn-Hilliard equation and the Fourier heat transfer equation in two dimensions. The Flory-Huggins free energy theory for the thermodynamics of phase separation, slow mode theory, and Rouse law for polymer diffusion without entanglements were taken into account in the model development. The simulation results indicated a strong interaction between heat transfer and phase separation, which impacted the morphology formation significantly. Results confirmed that quench depth had an indispensable impact on phase separation in terms of higher characteristic frequency by increasing the driving force for heat transfer. Applying quench from various boundaries led to a difference in the quench rate due to the high viscosity of the polymer solution. This led to a gradation in pore size and anisotropic morphology formation. The degree and direction of anisotropy depended on quench depth and rate, quench time, heat conduction rate inside the solution, solution viscosity, temperature evolution, and the enthalpy of demixing. It was also verified that the influence of enthalpy of demixing on phase separation could not be neglected as it increased the solution temperature and led to phase separation being accomplished at a higher temperature than the initial quench temperature.