Continuous Temperature Control Research Articles

Continuous light-guide control of melts temperature in induction furnaces

The article is devoted to the question of the most effective for the full use of the induction furnaces technological flexibility continuous temperature control. The aim of the work is to create a light-guide technology for continuous temperature control of the processes of induction melting, treatment and pouring of liquid metal in metallurgy of machine building. The investigations of crucible and channel, melting, holding and pouring induction furnaces from the standpoint of light-guide thermometry have been developed. Materials, designs, as well as technologies of manufacturing, mounting and safe operation of the light-guide and auxiliary devices have also been investigated. Using the results of complex studies, the base light-guide thermometry system, general and particular methods of the light-guide temperature measurements have been developed. On the base of the Huygens construction, as well as the laws of geometric and crystal optics, techniques for calculation of the optical characteristics of the light-guide and focusing devices, as well as schemes of their optical joint have been developed. These techniques increase the metrological characteristics of the light-guide thermometry. Standard construction of the secondary part of thermometry system requires classical pyrometry methods application. These methods are acceptable for continuously operated metallurgical aggregates, where stable emissivity of the light-guide operating end takes place. The secondary part of thermometry system has been modernized in order to widen application field of light-guide thermometry on periodically operated metallurgical aggregates where emissivity of light-guide immersion end randomly changes. Modernized secondary part is purposed for spectral (multicolor) pyrometry methods realization. These methods minimize influence of the instability of emissivity of light-guide immersion end on methodical errors of temperature measurements. Research and industrial exploitation, at domestic and foreign enterprises, have shown obvious metrological advantages of the light-guide thermometry technology in comparison with known solutions. Implementation of the light-guide thermometry systems on induction furnaces has high technical-economic efficiency, including by reduction the spoilage of metal products and resource costs for production. Keywords: induction furnace, continuous temperature control, light-guide thermometry, amorphous, poly- and single-crystalline materials, measurement error, Huygens construction, technical-economic efficiency.

РЕСУРСОЗБЕРІГАЮЧИЙ БЕЗПЕРЕРВНИЙ ОПТИЧНИЙ КОНТРОЛЬ ТЕМПЕРАТУРИ РІДКОГО МЕТАЛУ В МЕТАЛУРГІЇ ЕНЕРГЕТИЧНОГО МАШИНОБУДУВАННЯ

The article is devoted to the problem of the most effective and non-alternative continuous optical temperature control of metallurgical aggregates in machine building metallurgy. The aim of the article is to develop and investigate the technologies of continuous temperature control on the base of classical and spectral (multicolor) thermometry. To achieve thе aim, the next methods have been used: analysis of literature sources; experimental investigations of influence regularities of sighting zones, time of tapping, intensity of mixing and liquid metal temperature on one color radiation temperature of liquid metal in visible and infrared spectrum ranges under industrial conditions; statistical processing of the results of direct and indirect measurements with their errors estimation. It has been found the main role of thermometry in the metrological support structure of metallurgical plants. The production volumes of world machine building metallurgy have been analyzed, particularly, the part of metallurgy of energy machine building in it. Metallurgical equipment to be used for liquid metal obtaining and treatment has been classified from thermometric position. The stability of radiation characteristics of liquid metal in cupola, arc and induction furnaces has been investigated under conditions of different impact factors. The methodical errors of optical temperature measurements of liquid metal during tapping from cupola and arc furnaces on the base of classical energy thermometry have been estimated. In special determined сases these errors don’t exceed 1,0–1,5% with confidence level 0,997. Under another conditions these errors reaches 8% and this fact stimulates transition to the spectral thermometry. With the use of modern elemental base, the technologies of spectral measurements of temperature and emissivity have been developed. The technologies include: symmetric-wave, two-color compensative, as well as based on nonlinearity equation of emissivity spectral distribution. The temperature measurement errors of new technologies are lower than the same ones of known spectral, as well as classical energy and spectral ratio thermometry in 2,3; 11,7–20,0 and 6,1–7,6 times. Keywords: metallurgy of machine building, continuous optical temperature control, cupola furnace, arc furnace, classical and spectral thermometry.

Development of cryotherapy device using refrigerant compressor for decreased skin temperature

Cryotherapy is a commonly used technique in sports medicine and physical therapy for the treatment of acute injuries and pain management. The application of cold temperatures leads to a decrease in skin surface temperature, which can have several physiological effects on the body. This can help to reduce inflammation, swelling, and pain in the affected area. Cryotherapy can be administered using various modalities, but controlled continuous cold devices are widely used in cryotherapy treatment due to their accurate temperature control, especially when treating large joints. These devices work by pumping cold water alternately into a cooling pad that is wrapped around a patient's limbs. The aim of this study is to develop a cryotherapy device that regulates low skin temperature for effective physical therapy treatment. This will be achieved by utilizing a refrigerant compressor in combination with a remote source of chilled water that is circulated through a cooling pad placed on the treatment site. The results show that this device can control temperature from 20oC to 5oC with a fluctuation of ± 0.4oC at the cooling pad. A test study on 32 volunteers showed that the skin temperature in the knee area can drop to 15.1oC±1.7oC (95% CI, 18.6-11.1oC) after 30 minutes of applying a cooling pad at 10oC. The experimental cryotherapy results on the skin surface are consistent with the simulation test results, indicating that this device can be developed into a medical device that provides precise and continuous temperature control, thereby ensuring ease of use and maximum therapeutic benefit in the field of physical therapy.

Reliable and Traceable Temperature Measurements Using Thermocouples

Temperature is the most frequently measured process variable in almost all industrial sectors from the chemical industry to glass and ceramics, refrigeration and power generation. During many manufacturing processes, continuous temperature control is an important part of product quality assurance and a matter of avoiding malfunctions or detecting them at an early stage. Measuring points can be located at different places such as in containers, pipe systems, machines, ovens or reactors, whereby different gaseous, liquid or solid media, for instance, steam, water, oil or special chemical substances may be involved. In view of these extremely complex tasks, flexibility is one of the most important requirements for measurement technology and signal processing. And this is where thermocouples, which can be adapted to almost all measuring tasks due to their simple design, become relevant. The basic design and operating principle of thermocouples are described in this paper; issues relating to calibration, traceability and measurement uncertainty are addressed. Recent developments to improve temperature measurement with thermocouples are presented. New, drift-optimised thermocouples, novel designs and alternative calibration methods are described, and their advantages over conventional thermocouples or calibration methods are specified.

Optimization of Pre-cooling process of Hi-Lumi LHC twin-aperture correction superconducting magnet

The MCBRD magnets for the HL-LHC are now undergoing serial production in China and must be cold tested prior to shipment to CERN. To improve the efficiency and safety of the magnet, the pre-cooling procedure must be optimized. In this paper, A pre-cooler with continuous temperature control is designed, and a three-dimensional unstable CFD model of the magnet is developed in order to study the platform. In the model, a pre-cooler is employed to generate cold gaseous helium stream in order to cool the magnet. The helium is cooled by liquid nitrogen, circulated by a cryo-fan and supplemented by an electric heater for temperature regulation. The simulation yields the pre-cooling time and temperature distribution throughout the cooling operation. The results indicate that the MCBRD magnet can complete the pre-cooling stage in 72 hours with a maximum cooling rate of 6.92 K/h under the conditions of the pre-cooler's 1.8 kW cooling capacity and 60 K temperature difference. The cooling time is decreased by 37.9% compared to the previous indirect pre-cooling experiment, and the cooling process is stable and under control, with a maximum temperature difference of less than 30 K. This research aids in the formulation of an appropriate pre-cooling method for the early phase of magnet cold testing.

Synthesis and characterization of chitosan-based graft copolymers with temperature-switchable and self-adaptive plugging performance for drilling in microporous formation

The increasing oil–gas explorations in microporous formations and the intensified environmental requirements necessitate the development of high-performance, environmentally friendly and sustainable plugging materials to maintain wellbore stability in drilling engineering. In this work, a series of graft copolymers of carboxymethyl chitosan-g-poly(oligo(ethylene glycol) methyl ether methacrylate-co-acrylic acid) (GCOA) is synthesized through free-radical graft-from polymerization. The oligo(ethylene glycol) methyl ether methacrylate (OEGMA) and acrylic acid (AA) can be well copolymerized in the grafts as confirmed by structural characterizations, and the incorporation of AA improves the grafting ratio and grafting efficiency. All obtained GCOAs possess the temperature-responsive aggregation behavior, which causes the formation of aggregated meso-assemblies from original nano-micelles when heating above their lower critical solution temperature (LCST), accompanied by the phase separation. Meanwhile, the presence of AA segments increases the LCST due to the resistance of enhanced polymer–polymer electrostatic repulsion to the hydrophobic attraction. By the delicate control of AA molar ratio from 0 to 50 mol%, the LCST values of GCOAs can be adjusted from 90 °C to 110 °C. Furthermore, the GCOAs are formulated as smart plugging fluids and the intelligent plugging evaluation method is established based on core flow test with continuous temperature control. The results indicate that the GCOAs can form effective plugging in both low- and median-permeability cores when temperature reaches above a switching point and the formed plugging can be partially removed after cooling, showing the temperature-switchable and self-adaptive plugging capacity as a consequence of reversible retention of GCOA aggregates and thermo-thickening behavior in pore-throat spaces. These features enable the implementation and removal of in-situ plugging in the specific temperature sections during drilling, and provide a new insight into the design of novel smart plugging materials with sustainable and recycling values.

Energy efficiency in cold supply chains of the food and beverage sector

Food refrigeration during transport, and storage activities makes energy consumption in the supply chain particularly high, with relevant impacts on its sustainability. The growing push towards sustainability and product quality makes it necessary to have a continuous temperature control that allows to avoid food waste and temperature abuses with unmotivated high energy consumption. An efficient management of the cold chain guarantees product quality, customer satisfaction and, more generally, greater protection of public health, with direct impacts on the quantities of food and drinks wasted. In this perspective, energy efficiency not only encompasses benefits for the environment but also for food quality and for the final consumer. All aspects linked to the sustainable development goals, on which the attention of the UN and FAO is also focusing.Aim of the present study is to propose a quantitative approach to map the energy flows throughout the cold chain, while considering the time-temperature relationship of products from farm-to-fork. This approach can support decision makers inside cold chains in the identification of energy efficient best practices which allow to reduce the environmental impact both reducing the energy consumption and the quality losses. Results of the energy flow mapping also allow companies in the cold chains and cold logistic operators to prioritize these energy efficiency measures (i.e., starting from the stage with the highest energy consumptions or quality losses) and subsequent what-if analyses assess the potential energy savings for the whole cold chain. The holistic perspective can support the overcoming reservations to the uptake of new technologies, maintenance policies and sustainable operation management practices.

Bone Defect Repair: Injectable Affinity and Remote Magnetothermal Effects of Bi‐Based Alloy for Long‐Term Bone Defect Repair and Analgesia (Adv. Sci. 14/2021)

Bi alloy was injected in situ into bone defects to replace bone tissue for support. At the same time, compared with the transmission of nerve sensory information in the normal part, the continuous temperature control (40-45 °C) of Bi alloy induced by the remote alternation magnetic field of the magnetic coil blocked the transmission of pain signals from the nerve fibers around the bone defect to the spinal cord and brain, thus alleviating pain. More details can be found in article number 2100719 by Jing Liu and co-workers.

Constant temperature control system of building energy system

Due to the poor effect of traditional systems on constant temperature control, the paper proposes to design an embedded continuous temperature control system in a dynamic, intelligent building. In the smart building, the thesis takes the building as the research object and uses the embedded technology to design the overall structure diagram of the system. The thesis aims at the output control module of the thermostat. It uses the Peltier effect to develop the thermocouple closed-loop and drives the semiconductor refrigeration device select. In the software part, the paper establishes a cross-compilation environment, transplants embedded kernels, and sets fuzzy rules for constant temperature control. The validity of the system design is verified through experiments. It can be seen from the experimental results that the system has a better thermostat control effect.

Investigation of low-pressure cold-gas dynamic spraying of polyamide-12 (PA12) on steel surfaces

Due to their good tribological properties and corrosive resistance, thermoplastic coatings are becoming increasingly important in industrial applications. Thermal spray technologies in general and flame spraying in particular belong to the most common application methods. However, the high thermal energy inevitably leads to the risk of thermal decomposition, especially in the case of materials such as polyamide-12, which have a small discrepancy between the melting and degradation temperatures. Furthermore, flame-sprayed coatings often are highly porous, reducing its effectiveness as a corrosive barrier. As an alternative approach, polyamide-12 coatings were applied to steel substrates using a conventional low-pressure cold-gas dynamic spray system. Various mixtures including ceramic powders (Al2O3) as well as different injection concepts were investigated and evaluated. The focus was put on the resulting coating morphology. Furthermore, the cold-gas spraying system was modified with a continuous temperature control for the gas temperature to enable a more precise adjustment based on the melting temperature of the material in order to reduce the risk of thermal degradation.

Numerical study of influence of deep coring parameters on temperature of in-situ core

The In-situ coring has a significant effect on the exploration of deep earth. However, in deep hard rock coring, the cutting heat in the process of coring generates high temperature and causes fidelity distortion of the in-situ core. Exploration of the mechanism of heat effect in the coring process is necessary to achieve the continuous control of temperature and obtain in-situ core. Due to the lack of systematic study on the surface and internal temperature rise of core samples during coring process, this paper uses the finite element simulation study the heat effect on the surface of the core under the influence of various cutting parameters. The numerical simulation results show that the surface of the core will not be burned under the cutting speed of 100 mm/s. At the condition of cutting speed 100 mm/s, feed rate 0.03 mm/r, thermal conductivity coefficient 1 W/m?C, the whole temperature rise will not exceed 1?C. The interest results showed that cutting fluid has little effect on the temperature rise in the cutting process. If the requirement of core quality should avoid the pollution by drilling fluid, this study has supported the no drilling fluid for in-situ coring.

Focus on materials, semiconductors, vacuum, and cryogenics

Focus on materials, semiconductors, vacuum, and cryogenics

An <em>ex-ovo</em> Chicken Embryo Culture System Suitable for Imaging and Microsurgery Applications

Understanding the relationships between genetic and microenvironmental factors that drive normal and malformed embryonic development is fundamental for discovering new therapeutic strategies. Advancements in imaging technology have enabled quantitative investigation of the organization and maturing of the body plan, but later stage embryonic morphogenesis is less clear. Chicken embryos are an attractive vertebrate animal model system for this application because of its ease of culture and surgical manipulation. Early embryos can be cultured for a short time on filter paper rings, which enables complete optical access for cell patterning and fate studies. Studying advanced developmental processes such as cardiac morphogenesis are traditionally performed through a window of the eggshell, but this technique limits optical access due to window size. We previously developed a simple method to culture whole embryos ex-ovo on hexagonal weigh boats for up to 10 days, which enabled high resolution imaging via ultrasonography. These cultures were difficult to transport, limiting the types of imaging tools available for live experiments. We here present an improved shell-less culture system with a cost-effective, portable environmental chamber. Eggs were cracked onto a hammock created by a polyurethane membrane (cling wrap) affixed circumferentially to a plastic cup partially filled with sterile water. The dimensions of the circumference and depth of the hammock were both critical to maintain surface tension, while the mechanics of the hammock and water beneath helped dampen vibrations induced by transportation. A small footprint circulating water bath was also developed to enable continuous temperature control during experimentation. We demonstrate the ability to culture embryos in this way for at least 14 days without morphogenic defect or delay and employ this system in several microsurgical and imaging applications.

Behavior of hydrogen evolution of aqueous sodium borohydride solutions

Characteristics of hydrogen evolution from non-stabilized and alkali-stabilized sodium borohydride solutions were systematically studied in order to understand the fuel storage features of borohydride in fuel cell applications. The effects of the sodium borohydride concentration, the temperature of the hydrolysis reaction, the sodium metaborate concentration, and the continuous temperature control for alkali-stabilized sodium borohydride solutions on the hydrogen generation and yield were investigated. Temperature variation was the major parameter that affected the stability of sodium borohydride solutions with and without stabilizing agents during hydrogen storage.

Small-volume, ultrahigh-vacuum-compatible high-pressure reaction cell for combined kinetic and in situ IR spectroscopic measurements on planar model catalysts

We describe the design and performance of a high-pressure reaction cell for simultaneous kinetic and in situ infrared reflection (IR) spectroscopic measurements on model catalysts at elevated pressures, between 10−3 and 103mbars, which can be operated both as batch reactor and as flow reactor with defined gas flow. The cell is attached to an ultrahigh-vacuum (UHV) system, which is used for sample preparation and also contains facilities for sample characterization. Specific for this design is the combination of a small cell volume, which allows kinetic measurements with high sensitivity under batch or continuous flow conditions, the complete isolation of the cell from the UHV part during UHV measurements, continuous temperature control during both UHV and high-pressure operation, and rapid transfer between UHV and high-pressure stage. Gas dosing is performed by a designed gas-handling system, which allows operation as flow reactor with calibrated gas flows at adjustable pressures. To study the kinetics of reactions on the model catalysts, a quadrupole mass spectrometer is connected to the high-pressure cell. IR measurements are possible in situ by polarization-modulation infrared reflection-absorption spectroscopy, which also allows measurements at elevated pressures. The performance of the setup is demonstrated by test measurements on the kinetics for CO oxidation and the CO adsorption on a Au∕TiO2∕Ru(0001) model catalyst film at 1–50 mbar total pressure.

Impedance based DNA chip for direct Tm measurement

Si/SiO 2 chips were used to detect the hybridization of immobilized Oligo d(T) 20 through impedance measurement. The immobilization procedure involved an aminopropyl silane grafted silicon oxide surface activated by glutaraldehyde and subsequently modified by an aminolinker supporting oligonucleotides. The immobilization procedure was optimized and, in the best conditions, the hybridization of the immobilized oligonucleotide was able to generate a 50 Ω impedance change at an applied dc potential of −300 mV. The optimized DNA sensor was then used to directly determine the immobilized oligonucleotide T m via impedance measurement in a continuous temperature control flow system. A reproducible and specific 65 Ω impedance change was observed at 32 °C with a step duration as low as 15 min. This value compared well with the 31.4 °C theoretical value calculated from the sequence base pair composition and length.

Influence of hypothermia on cell volume and cytotoxic swelling of glial cells in vitro.

In view of the increasing significance of mild hypothermia (32 degrees C) as an efficient procedure of neuroprotection, the present study was performed to examine the influence of this level of hypothermia on the volume of glial cells under physiological as well as under pathological conditions. The influence of mild (32 degrees C) and moderate (27 degrees C) hypothermia on cell volume and cell viability of C6 glioma cells was studied for 60 minutes in vitro. Cells were suspended in an incubation chamber under continuous control of temperature, pH and pO2. Cell volume was measured by an advanced Coulter system. Hypothermia itself was causing significant cell swelling in a dose-dependent manner, which could be prevented by omission of Na(+)-ions from the suspension medium, while the replacement of Cl(-)-ions failed to prevent cell swelling from hypothermia. Inhibition of the Na+/H(+)-antiporter with EIPA (5N-ethyl-n-isopropyl-amiloride, 50 microM) was significantly reducing the hypothermia induced cell swelling, indicating activation of the Na+/H(+)-antiporter. Conversely, mild or moderate hypothermia failed to prevent cell swelling from lactic acid, arachidonic acid or glutamate, i.e. agents which are mediating the development of cytotoxic brain edema in vivo in cerebral trauma, ischemia and other acute insults. The findings indicate that cerebral protection by hypothermia in vivo is most likely not attributable to an inhibition of cytotoxic brain edema. Further investigations, however, are required in vivo and in vitro to elucidate the hypothermia-induced swelling of glial cells in more detail, e.g. as to the role of the Na+/H(+)-antiporter.

Temperature Controled Photoelectron Spectroscopic Investigation of Volatile Species on PbS(100) Surface

A special sample precooling technique has been utilised to preserve thin layers of volatile chemical species on the sample surface in ultra high vacuum conditions for investigation with conventional and synchrotron excited photoelectron spectroscopy. The precooling system has been constructed for the Scienta 300 electron spectrometer at the beam line 51 at MAX I synchrotron laboratory in Lund (Sweden) and it will be transferred to beam line 411 at the new MAX II storage ring. The spectrometer also includes a possibility for continuous temperature control of the sample during the measurement at temperature range 70 K – 450 K. In this work, temperature controlled measuring technique has been applied in a study of electrochemically treated PbS (100) surface. The measured sulfur 2p core level spectra clearly reveal a layer structure of elemental sulfur and metal polysulfides formed during anodic oxidation of PbS in acidic aqueous solution. Similar measuring technique can also be applied, e.g., in studies of adsorption layers on various substrates.

Simulation of the transient response of heat driven refrigerators with continuous temperature control: Simulation de la réponse transitoire des réfrigérateurs utilisant une source de chaleur avec maı̂trise de la température en continu

A theoretical and experimental study is presented and a mathematical model is introduced for a heat driven refrigeration system operating with continuous temperature control. The model consists of a refrigerated space, an absorption refrigerator, operating irreversibly, a temperature sensor and a reference signal, and a power law control action. The steady-state behavior of the absorption refrigerator model is validated by direct comparison between theoretical results and experimental data. The model is then used to identify an optimal thermal conductance allocation, for a fixed total thermal conductance inventory, such that the refrigeration rate is maximized and the `pull-down' time is minimized. A simulation of the system operating in a transient mode is carried out to show that closed-loop operation results in a large reduction of fuel consumption, with respect to the `on–off' operation. Appropriate dimensionless groups are identified and the generalized results reported in charts using dimensionless variables.

Expeditious routes to 4-alkoxyquinazoline-2-carbonitriles and thiocarbamates viaN-arylimino-1,2,3-dithiazoles using microwave irradiation

Conversion of N-arylimino-4-chloro-5H-1,2,3-dithiazole 11 into the 4-alkoxyquinazoline-2-carbonitriles 13a-i and of the aryl isothiocyanates 15 into aryl thiocarbamates 16a-j with sodium alkoxides in the corresponding alcohol, either by conventional thermolysis or by microwave irradiation are described and directly compared. Microwave irradiation of the solutions in open vessels in a monomode system with focused irradiation and continuous temperature control (Synthewave S402 reactor) usually gave cleaner, faster and higher yielding reactions. These reactions could be safely and beneficially scaled up to multigram quantities in a larger reactor (Synthewave S1000).