Changes In Temperature Field Research Articles

Study on Ice Temperature Fields and Borehole Closure Rates During Thermal Ice Drilling

Thermal ice drilling technology is extensively used in drilling operations such as temperature measurement holes and subglacial water environment investigations in Antarctica owing to its advantages of compactness, light weight, and ease of operation. However, thermal drilling disturbs the initial temperature of the surrounding ice, making it impossible to obtain the true ice temperature through a borehole within a short period. Meltwater refreezing also causes the borehole to shrink and close, posing a threat to drilling safety. Therefore, obtaining an accurate characterization of the temperature field around the hole and assessing the meltwater refreezing rate are crucial for determining the appropriate temperature measurement duration and optimizing drilling parameters. To address this issue, a temperature measurement platform for the ice surrounding the borehole was developed. Experimental investigations were conducted to analyze the temperature fields during thermal drilling using both small-diameter thermal heads and RECoverable Autonomous Sonde (RECAS) thermal heads. This study clarifies the temperature field changes in the surrounding ice during and after thermal drilling. It also elucidates the effects of parameters such as the ice temperature, thermal head heating power, and thermal head diameter on the temperature field around the hole and estimates the meltwater refreezing rate inside the borehole. The results indicated that the temperature of the surrounding ice peaked approximately 5–7 h after drilling and subsequently decreased and returned to the original temperature within 48 h. The thermal disturbance radius in the surrounding ice was approximately 1.1 to 1.7 times the borehole radius when the thermal head passed through. However, after the thermal head passed, the thermal disturbance radius continued to expand owing to the heat released from meltwater refreezing, reaching 9.7 to 12.5 times the borehole radius. The average meltwater refreezing rate, estimated from temperature measurement tests at −16 °C, was 3.6 mm/h.

Experimental investigation on the performance of a borehole thermal energy storage system based on similarity and symmetry

Although Borehole Thermal Energy Storage (BTES) technology has achieved significant progress in feasibility and sustainable energy integration, high heat loss and long preheating periods still strongly restrict its charging and storage performance. This investigation designed and constructed a laboratory-scale BTES sandbox based on similarity and symmetry principles. Detailed monitoring of sand temperature data and boundary conditions validated the effectiveness of the symmetrically simplified similarity experiment. The data comprehensively reflected the change of underground temperature fields during the charging and seasonal storage phases. The reasons for the performance limitations of BTES are thereby analyzed. During the charging phase, the prototype BTES achieved its highest average charging rate of 220W within the first 21 days, and the temperature field stabilized after 192 days. In the storage phase, the exergy destruction losses of BTES primarily occurred at the junction between the core and peripheral zones, accounting for 56 % of the total losses. An effective method to enhance BTES performance is to reconfigure the borehole layout and operation, which improves the uniformity and continuity of the underground temperature field. The experimental measurement provides fundamental data for the integrated seasonal utilization of heating and cooling, which can be essential for innovative building energy systems.

Analysis of the influence of thermal insulation parameters on the effectiveness of enclosing structures and building heating systems

The results of thermal engineering calculations of external multilayer enclosing structures of buildings and the thermal power of the heating system of residential buildings are presented, including calculations of temperature fields and partial pressures of water vapor at various parameters of structural layers and thermal insulation layers. Variants are considered and an assessment is given of the variation of parameters and the different location of thermal insulation in external multilayer fences for changes in temperature fields and partial pressures of water vapor in the fence, as well as for changes in the thermal power of the heating system of the building premises for two climatological design areas. The calculations were performed according to the methodology presented below using a specially developed computer program.

A new method for temperature field characterization of microsystems based on transient thermal simulation

Microsystems face challenges such as high heat flux density and localized hot spots in the temperature field, significantly impacting their thermal reliability. Accurately and comprehensively characterizing the temperature field is a challenging problem in current research. We present a general high-order finite difference (GHOFD) algorithm for the high-accuracy numerical solution of the two-dimensional transient heat conduction equations (THCEs). The 10th-order GHOFD algorithm is accurate up to 10−7 °C. Secondly, we present a viable approach for characterizing microsystems' steady-state and transient heat conduction mechanisms. We introduce two new characterization parameters: the gradient modulus and the heat flux direction factor (HFDF). The gradient modulus can more clearly characterize the magnitude of the gradient vector and quantitatively analyze the spatial position of the temperature field change in the microsystem. The HFDF can dynamically display the heat conduction process in the temperature field. Finally, using temperature field simulation and microsystem characterization, we have validated the effectiveness of the proposed method and new parameters.

A Review of Advanced Hydrogel Applications for Tissue Engineering and Drug Delivery Systems as Biomaterials.

Hydrogels are known for their high water retention capacity and biocompatibility and have become essential materials in tissue engineering and drug delivery systems. This review explores recent advancements in hydrogel technology, focusing on innovative types such as self-healing, tough, smart, and hybrid hydrogels, each engineered to overcome the limitations of conventional hydrogels. Self-healing hydrogels can autonomously repair structural damage, making them well-suited for applications in dynamic biomedical environments. Tough hydrogels are designed with enhanced mechanical properties, enabling their use in load-bearing applications such as cartilage regeneration. Smart hydrogels respond to external stimuli, including changes in pH, temperature, and electromagnetic fields, making them ideal for controlled drug release tailored to specific medical needs. Hybrid hydrogels, made from both natural and synthetic polymers, combine bioactivity and mechanical resilience, which is particularly valuable in engineering complex tissues. Despite these innovations, challenges such as optimizing biocompatibility, adjusting degradation rates, and scaling up production remain. This review provides an in-depth analysis of these emerging hydrogel technologies, highlighting their transformative potential in both tissue engineering and drug delivery while outlining future directions for their development in biomedical applications.

Heat transfer research on the cooling process of waxy crude oil storage in the vault tank based on VOF model

This paper focuses on the static cooling process for waxy crude oil stored in dome roof tanks. For the three phases of gas on top, liquid crude oil, and bottom water in storage tank, the VOF method is used to describe the evolution of physical quantities at the “oil–water”/“oil–gas” interface. The porous medium method is used to quantitatively characterize the sol–gel conversion process for waxy crude oil. A physical and mathematical models are established to describe the flow-heat transfer coupling behavior of the three-phase medium of crude oil, gas on top, and water at the bottom of the dome roof tank. In terms of the overall cooling process,The gas at the top of the tank has the simplest and fastest physical field evolution. It has the most uneven distribution (average temperature variance of 4 °C2), the strongest flow (average flow velocity of 0.4 m/s), the highest cooling rate (0.632 °C/h), and the lowest temperature (14.84 °C at the end). Its physical field is influenced by both the atmosphere and crude oil. The evolution of the physical field of crude oil is the most complex. It lags behind the gas at the top of tank and is directly effectted by it. Based on the evolution characteristics of the flow field of crude oil, the cooling process is divided into three stages: Stage I (0–––10 h) is the stage of convection generation and evolution in the crude oil region; Stage II (10 h − 34 h) is the stage of convection stability in the crude oil region; Stage III (after 35 h) is the stage of flow field transformation of crude oil. In stages I and II, the flow and momentum exchange at the oil–gas interface are significant. Crude oil is jointly influenced by the natural convection of the gas at the top of the tank and its own natural convection, forming a counterclockwise large vortex structure. The low-temperature area is near the central axis boundary of storage tank, oil–gas interface, and tank wall. The high-temperature area is within a range of 0.1 m − 3.3 m from the tank wall. After entering stage III, the flow and momentum exchange at the oil–gas interface weaken. The flow field of crude oil is only controlled by its own natural convection and transforms into a clockwise large vortex dominated. The low-temperature area is concentrated in the enclosed area of “oil–gas interface − tank wall” and “oil–water interface − tank wall”. The temperature field changes accordingly. Eventually, the high-temperature area is concentrated in the area slightly above the center of the tank. The physical field evolution of bottom water lags behind crude oil and is most unstable. Its cooling rate is 0.164 °C/h, slightly higher than crude oil’s 0.157 °C/h. The temperature is always slightly lower (33.47 °C at the end), and the physical field is the most uniform (average temperature variance of 0.0003 °C2), affected by the tank bottom environment and liquid crude oil.

C-type two-thermocouple sensor design between 1000 and 1700 °C.

At the present stage of transient ultra-high-temperature energy release of boron-containing warm-pressure explosives, single thermocouples are often used for multi-point measurements in the process of their temperature field changes, and the results of their temperature field reconstruction are not satisfactory due to the limited consistency of the thermocouples. Aiming at the above-mentioned problems, a C-type two-thermocouple suitable for transient temperature measurement in high-temperature environments is designed; the system characterization of the two-thermocouple is carried out by using the blind system identification method of the inter-relationships; the identification process is evaluated by a new cost function; and the optimal solution on the new cost function is realized by using the gradient descent method. The temperature reconstruction of the two-thermocouple output excited by the simulated heat source is carried out by using the auto-regressive with extra inputs model, and the feasibility of the reconstruction results is verified. In the experimental part, a thermocouple dynamic characteristic calibration system based on a high-temperature furnace is constructed and experimental validation is carried out in the high-temperature furnace to compare the effects of different exposure lengths and different wire diameters on the output of the two-thermocouple, and as a result, the outputs are corrected and analyzed. The results show that two-thermocouple methods with different combinations of wire diameters are better for temperature measurement, with a reconstructed root mean squared error of 0.0162 and a goodness of fit of 89.13%.

Multi-region coupling computational fluid dynamics simulation of the underground compressed air energy storage process

Compressed air energy storage (CAES) in underground spaces is a common method for addressing the instability of renewable energy generation. As the construction and testing of CAES systems are often of high cost, the numerical simulation which offers a more efficient and low-cost research method can provide a better alternative to research the process. In this study, a numerical simulation model has been developed to describe the air movement within the CAES process. Specifically, the study focuses on two different types of motion: air compressible flow within the cavern and air porous flow in the surrounding rock. Using OpenFOAM, a multi-region coupling solver has been developed to address the different governing equations for these two types of motion, and couples pressure, velocity, and temperature at the boundaries. The developed solver is used to simulate a field test of a CAES system. The numerical simulation results closely match the experimental data, verifying the reliability of the solver. Moreover, the solver can achieve multi-region flow simulations that are previously unattainable, resulting in more accurate simulations. Simulations have also been conducted to analyze various working conditions, including different rock permeability, porosity, and air injection mass rates. The results show that different conditions significantly affect air pressure, leakage rate, temperature, and flow field changes within the cavern. These simulation results and the underlying mechanisms have been analyzed to provide reference and technical support for site selection, construction, and operational strategies of CAES systems in underground spaces.

Simulation of the Process of Temperature Field Changing of a Zr–1%Nb Zirconium Alloy Billet During Equal-Channel Angular Pressing

Using mathematical modeling in the QFORM software package, the data on the temperature distribution of a billet made of a zirconium alloy E110 (Zr–1%Nb) in its longitudinal and transverse sections during an equal-channel angular pressing (ECAP) were obtained. The initial data on the geometric parameters of the billet and the die of the ECAP unit are presented, and the conditions for carrying out the process of severe plastic deformation, as well as the chemical composition and physical characteristics of the Zr–1%Nb alloy necessary for carrying out the computational modeling are described. The values of the billet temperature were determined for the calculated moments of the passage of the billet through the junction of the die channels, which corresponded to 25%, 50%, and 75% of its length. It is shown that during the ECAP process at a given pressing speed, in the section corresponding to the junction of the matrix channels, an increase in the billet temperature relative to its initial heating occurred by an amount of about 10 ºC.

Heat transfer mechanism of superabsorbent polymers phase change energy storage cold-formed steel wall under fire

The superabsorbent polymer phase change materials (SAP materials) exhibit exceptional water absorption and retention properties, offering substantial potential for fire protection in steel structures, thereby reducing the need for sheathing boards and fire-retardant coatings, while minimizing energy consumption. Understanding the heat-mass exchange theory of SAP materials is crucial for enhancing their application in the building industry. This study develops a comprehensive theoretical model for heat-mass exchange in cold-formed steel (CFS) walls incorporating SAP materials. An equilibrium phase change model and a simplified thermal radiation model were developed to capture the water loss and dynamic heat exchange processes in SAP materials. These models were integrated into a transient fluid-solid-thermal coupling model using Ansys Fluent and User Defined Functions. In the case study, the newly developed numerical models can accurately predict temperature field changes in CFS walls with SAP materials, demonstrating the heat transfer mechanisms of hot and cold flanges at different temperature rise stages. The developed numerical model was used to investigate the effects of factors such as the moisture content of the SAP material, web depth, and flange width on the fire resistance of the CFS wall. Results indicated that increasing the wall stud height improves fire resistance, while increasing flange width has little effect on hot flange temperature. These findings provide a theoretical foundation and practical guidelines for the application of SAP phase change insulation materials in the building industry, promoting energy reduction and supporting sustainable construction practices.

Finite Element Method Simulation Study on the Temperature Field of Mass Concrete with Phase Change Material

Phase change materials can be converted between solid, liquid, and gaseous states, absorbing or releasing a large amount of heat. PCM is incorporated into concrete to adjust the temperature difference between inside and outside of concrete, which can reduce cracking. In this paper, the finite element analysis method is used to establish the model of an ordinary concrete structure, doped with phase change materials, on the basis of mechanical properties and a temperature regulation test performed by calculating the adiabatic temperature rise of concrete with different contents of composite phase change material, comparing the experimental and simulation results of the ordinary concrete structures with phase change materials, and analyzing the change in temperature field of the concrete structure with the content of self-prepared composite phase change materials. It is found that the addition of self-prepared composite phase change materials reduces the temperature peak of the concrete structure in the stage of hydration heat and delays the time taken to reach the temperature peak. Then, the temperature field of the phase change mass concrete structure is established, and the influence law of composite phase change material admixture on the temperature field of mass concrete is summarized through the time–temperature curves of different admixture amounts and positions so as to predict the possibility of cracks in mass concrete.

Thermal effect on the flow induced by a single-dielectric-barrier-discharge plasma actuator under steady actuation

The thermal effect of a single-dielectric-barrier-discharge plasma actuator under steady actuation is numerically investigated. A new actuator model is proposed and validated using experimental data. A discrete Galerkin method based on high-order flux reconstruction schemes is employed to solve the flow governing equations and the actuator model equations on unstructured quadrilateral grids. By comparing the induced heated and cold flow fields of the actuator with and without a plasma thermal source, its thermal effect is revealed. The actuator generates a thermal wall jet with rich vorticity, forming a monopolar starting vortex with a high-temperature and low-density core. Over time, the starting vortex becomes unstable and transforms into a dipole. Actuator heating enhances jet velocity and width, as well as vortex stability, while slowing down vorticity generation. The relative change in density and temperature fields due to actuator heating is four orders of magnitude greater than that without actuator heating. Additionally, the actuator heating causes the background thermodynamic fields to increase approximately linearly with time. Two stages in the actuator's thermal effect are distinguished due to time accumulation. Initially, the actuator heating minimally affects the monopolar starting vortex motion, and the temperature and density fields are treated as passive variables driven by the velocity field. During this stage, the momentum and thermal effects of the actuator can be studied separately. However, after the starting vortex becomes unstable, the actuator heating significantly impacts its motion and morphology, and these two effects are coupled with each other.

Analysis of the temperature rise process of carbon ceramic axle-mounted brake disc

Abstract At present, high-speed train braking modules gradually adopt carbon ceramic brake discs. Based on the calculation results, the temperature simulation calculation of carbon ceramic brake disc for high-speed trains is of important engineering reference value for design and application. This paper established a finite element thermal simulation model based on the material properties of carbon-ceramic composite materials and the size and structural characteristics of the brake disc, and conducted a simulation analysis of the 400km/h emergency braking condition. After calculation, the carbon ceramic disc surface temperature reaches about 1250°C during the braking process, which does not exceed the material limit of 1350°C, and can adapt to the braking requirements of high-speed trains. The evolution rules of the temperature field and temperature value changes of the carbon ceramic shaft-mounted brake disc were further studied, and the general rules of disc temperature changes during emergency braking at 400km/h were summarized. The relevant content can provide a reference for the thermal analysis research of carbon ceramic axle-mounted brake disc.

Photonic Crystal Fiber Based on Surface Plasmon Resonance Used for Two Parameter Sensing for Magnetic Field and Temperature

This paper presents a photonic crystal fiber (PCF) sensor that can be used to measure the temperature and magnetic field simultaneously, and to monitor the changes in them in the environment. When we designed the fiber structure, two circular channels of the same size were added to the fiber to facilitate the subsequent addition of materials. A gold film is added to the upper channel (ch1), and the channel is filled with a magnetic fluid (MF). The sensor can reflect changes in the temperature and magnetic field strength. The two channels containing MF and PDMS in the proposed fiber are called ch1 and ch2. The structure, mode and properties (temperature and magnetic field) were analyzed and discussed using the finite element method. By using the control variable method, the influence of Ta2O5 or no Ta2O5, the Ta2O5 thickness, the diameter of the special air hole, the distance from the fiber core and the distance between them in the displacement of the loss spectrum and the phase-matching condition of the coupling mode were studied. The resulting maximum temperature sensitivity is 6.3 nm/°C (SPR peak 5), and the maximum magnetic field sensitivity is 40 nm/Oe (SPR peak 4). Because the sensor can respond to temperature and magnetic field changes in the environment, it can play an important role in special environmental monitoring, industrial production and other fields.

Simulating Error Due to Acquired Thermoelectric Inhomogeneity.

The best method to prevent error due to inhomogeneity is to use a new thermocouple design-the thermocouple with controlled temperature field (TCTF). It uses the auxiliary furnace to control the temperature field along its legs. Such a design allows setting and maintaining the temperature field along the thermocouple (TC) legs for the sensor. Error due to inhomogeneity of TCs cannot appear in a stable temperature field. However, the auxiliary furnace and TCs, to control the temperature field, have errors, so the temperature field along the main TC is maintained with some error. This leads to residual error due to acquired inhomogeneity of the TCTF. We constructed the mathematical models to fit the experimental data of error due to drift for the type K TC. The authors used the constructed models to study error due to inhomogeneity of the TCTF and the conventional type K TC under considerable changes in temperature field. The main results of modelling are as follows: (i) if the changes in temperature field exceed 7 °C, error due to inhomogeneity of the TCTF is lesser than that of the conventional TC; (ii) the maximum error due to inhomogeneity of the conventional type K TC is 10.75 °C; (iii) the maximum error due to inhomogeneity of the TCTF is below 0.2 °C.

High-resolution monitoring of soil infiltration using distributed fiber optic

Monitoring the infiltration process in soil is of great importance in various fields. However, the majority of existing infiltration monitoring methods have certain limitations that hinder their ability to meet the technical requirements for continuous spatial monitoring of the infiltration process. To address this issue, this study proposes a new method for achieving spatially continuous monitoring of the infiltration process. This method employs the improved Active Heating Fiber Optics (AHFO) technique as the underlying mechanism and utilizes Optical Frequency Domain Reflectometry (OFDR) monitoring technology characterized by exceptionally high spatial resolution and monitoring sensitivity. The proposed method, referred to as Active Heating Optical Frequency Domain Reflectometry (AH-OFDR). The feasibility of AH-OFDR was validated through a set of experimental tests, involving the installation of optical fibers within cylindrical soil samples for infiltration monitoring. A comparison was conducted between the infiltration patterns obtained through AH-OFDR and those acquired using the well-established Distributed Temperature Sensing (DTS) method. Additionally, the temperature distribution within the sample during the infiltration process was monitored by employing infrared thermography technology. The experimental results demonstrated an excellent agreement between the infiltration patterns obtained through AH-OFDR and DTS, reaffirming the viability and accuracy of AH-OFDR for soil infiltration monitoring. However, when compared to DTS, AH-OFDR excels in achieving dynamic monitoring of water content variations at a spatial resolution as fine as the centimeter level, empowering high-resolution and continuous monitoring. The changes in the soil temperature field recorded by the infrared thermography system further confirm the accuracy of the AH-OFDR monitoring results.

Ground Temperature Monitoring and Simulation of Temperature Field Changes in Block-Stone Material Replacement Foundation for the Shiwei–Labudalin Highway

The current thermal balance of permafrost in northeastern China has been upset by human engineering construction disturbances and global warming. This has resulted in a rise in ground temperature and a fall in the permafrost table, which has a major impact on the stability, longevity, and operational safety of highway subgrades. To solve the issues above, the ground temperature monitoring data at K60+230 of the Shiwei–Labudalin highway were analyzed, and the numerical simulation of the temperature field change over 15 years was carried out for the ordinary subgrade as well as for sections of block-stone material subgrade with 1 m of straight-filled and different thicknesses of replacement fill (1 m, 2 m, 3 m, 4 m) by applying Comsol Multiphysis software. The results show that the temperature field of the subgrade exhibits significant asymmetry. There are variations in the rate of decline at different sites during the course of the 15 years when compared to where the permafrost table was located at the start of the study. Still, the rate of decline of the permafrost table is decreasing yearly. The straight-filled 1 m block-stone subgrade has a permafrost table 0.77 m higher in the bottom portion of its top surface than the ordinary subgrade. The replacement 1 m, 2 m, 3 m, and 4 m block-stone subgrade has a permafrost table in the lower portion of the top surface that is 1.05 m, 2.12 m, 3.32 m, and 4.75 m higher than the ordinary subgrade. The replacement block-stone subgrades, as opposed to ordinary subgrades, can strengthen the foundation, raise the permafrost table, and effectively reduce the impact of the upper boundary temperature on the lower permafrost. They can also increase the stability of permafrost subgrades. Of them, the block-stone filling with a thickness of 4 m and a particle size of 6–8 cm had the best impact.

A temperature field model based on energy flow analysis of wet clutch sliding interface

A fluid-solid convective heat transfer model is constructed according to the velocity distributed calculation of lubricant in clutch groove cavity. Considering the characteristics of circumferential alternation of heat dissipation and generation area on separator plate surface,the effective energy flow characterization equations of convective hear transfer and heat generation at sliding interface are established. The non-heat source temperature field is proposed by effective convective heat transfer and heat conduction. Following the target constraint of continuous contact temperature, the temperature field change is solved during actual dynamic heat flux partition period. The tests with different intensity of heat generation and dissipation are designed, which indicates the reliability of model. The research provides a new method for the temperature field calculation of clutch.

Mixed convection heat transfer characteristics of nanofluid under magnetic field based on discrete unified gas kinetics scheme

In this paper, we proposed a discrete unified gas kinetic scheme (DUGKS) into the mixed convection issue coupled in a magnetic field and verified the accuracy by comparing with a exist literature. The flow and heat transfer characteristics of Fe3O4-water nanofluid in the mixed convection are investigated using the DUGKS model. The investigation explores the influence of Hartmann number (0.01 ≤ Ha ≤ 100), Rayleigh number (2 × 103 ≤ Ra ≤ 6 × 105), Richardson number (0.5 ≤ Ri ≤ 10), and nanoparticle fraction (0.01≤ϕ ≤ 0.05) on mixed convection heat transfer and flow characteristics. The results reveal that the critical point for the influence of the Hartmann number on the average Nusselt number is 1. When Ha < 1, the variation of Ha has little effect on Nu, but when Ha > 1, the influence of Ha becomes significant. When Ri = 1, the heat convection between the cold wall and the hot wall is strongest, and the Nusselt number at the cold wall reaches its maximum. The changes in velocity and temperature fields under all conditions are effectively captured by the DUGKS method. Therefore, the proposed method exhibits good mesh adaptability and accurately simulates the mixed convection heat transfer problem.

Coupling drying of wet and heat field of corn pile based on porous medium model

AbstractCorn that are not properly dried can result in a lot of waste. Therefore, in this study, the corn pile was used as porous medium for hot air drying, and the coupling method of multiple physical fields was used to simulate and analyze the corn air‐drying silo with different initial conditions and different sizes. The results show that increasing the temperature of hot air could increase the temperature gradient inside corns and promote the evaporation of water. The higher the wind speed, the better the convective heat transfer effect between corn and air, thus improving the drying efficiency. The smaller the ratio of height to diameter of air‐drying silo, the more corn dried in the direction of hot air flow, resulting in poor drying effect. Increasing the inner diameter of the air‐drying silo will reduce the heat transfer efficiency. The lower the bed of the air‐drying silo, the closer the corns are to the hot air inlet, the faster the heating rate and the better the drying effect. The model has good performance and can be used as a mathematical tool to predict the change of maize wet heat field.Practical applicationsIn order to solve the integral problem of corn drying, the model uses corn grain pile as porous medium for hot air drying. The model investigated the changes of temperature field and humidity field during the drying process of grain pile in corn air‐drying silo. In addition, the characteristics of the model introduced in this study may qualify it for automatic control of corn air‐drying silo and online prediction of drying times to achieve the desired drying effect.