Experimental Temperature Data Research Articles

Thermal State of the Lithosphere of Patagonia Via Data of the Xenoliths

Ultramafic xenoliths and minerals present in intrusive rocks make it possible to infer the temperature and pressure of the upper mantle and lower crust, since they preserve their physical and chemical characteristics while being transported by magmatic processes. Thermal models incorporating thermo-barometric data have been developed to estimate the thermal field. Thus, the objective of this work is to use mineralogical temperature and pressure equilibrium information to estimate lithospheric thermal field in the Patagonian region bounded by latitudes 40º - 52º S and longitudes 67º - 71º W, these coordinates correspond to the Argentine provinces of Río Negro, Chubut and Santa Cruz. Experimental mineral temperature data indicate ranges of 917-1029 ºC in the Chubut province, 877-1253 ºC in the Río Negro region and 728-1196 ºC in the Santa Cruz province. The average heat flux and temperature values at the Moho depth are 40 mWm-2 and 734 ºC, respectively. Río Negro province has the highest temperature (760 ± 45 ºC) and the lowest thermal thickness value (75 ± 11 km), while Santa Cruz province has the highest heat flux (44 ± 7 mWm-2) at Moho depth, which indicates that there are possibly two plumes responsible for the deposition of xenoliths in the region: one in Río Negro province and the other in Santa Cruz.

A Probabilistic Model for Forging Flaw Crack Nucleation Processes for Heavy Duty Gas Turbine Rotor Operations

Abstract We present a probabilistic model for quantifying the number of load cycles for nucleation of forging flaws—for a 3.5NiCrMoV high strength low alloy rotor steel—into a crack under gas turbine operating conditions. The model correlates low cycle fatigue data, ultrasonic testing indication data, flaw morphology, and type with the nucleation process. This paper is the third of a series of publications presenting this modeling approach progressively. It focuses on the effect of temperature variation on the nucleation life of forging flaws. We quantified the number of cycles to crack nucleation was for specimens that included forging flaws at elevated temperatures. Flaws of different sizes and shapes are effectively described at respective temperature and stress levels by either an ellipsoidal finite element model or an analytical area-based model. A local probabilistic low-cycle fatigue model analyzes the resulting stress distributions accounting for statistical size effects. Via Maximum Likelihood Estimation of these probabilistic low cycle fatigue results, a probabilistic model for crack nucleation of forging flaws is obtained. This proposed probabilistic model is based on experimental data for realistic heavy duty gas turbine rotor temperature and stress conditions. It can be utilized in the energy sector for component life time quantification. Our suggested approach can support component assessment under flexible gas turbines operation conditions driven by increased availability of intermittent renewable energy sources.

Conjugate Heat Transfer Analysis and Heat Dissipation Design of Nucleic Acid Detector Instrument

Temperature affects both the stability of nucleic acid detectors and efficiency of DNA amplification. In this study, temperature and flow inside a nucleic acid detector were simulated and the results were used to design vents for the instrument casing. A test platform was constructed to collect experimental temperature data that were used for simulation validation. The experimental and simulation results showed that the temperature error was less than ±3 K. A total of two heat-dissipation schemes were designed based on the simulation and a new instrument casing was fabricated based on the scheme with the best results. Nucleic acid amplification was performed continuously for 120 min using a prototype with the new casing. The temperatures of the monitoring points were stable and the maximum temperature measured only 307.76 K (34.61 °C). Therefore, waste heat was effectively eliminated, which ensured safety of the electronic components and stability of the nucleic acid detection process.

Potential use of recycled materials on rooftops to improve thermal comfort in sustainable building construction projects

The study has two objectives. First, it experimentally measures the indoor and outdoor temperatures of a building in Peshawar and conducts validation with CFD modeling. Second, it simulates the building with the addition of locally available, natural, and recycled insulator materials on the rooftop to keep the indoor environment within a comfortable temperature range, especially in the winter and summer seasons. To achieve these objectives, experimental temperature data for January and June were recorded and validated, followed by a simulation, using ANSYS-Fluent 16 CFD, of the residential building with the application of waste thermal insulators such as straw bale, sheep wool, and recycled glass materials on the rooftop to reduce the indoor temperature. Experimental temperature measurement showed that the lowest recorded indoor temperature was 15°C on 2 January 2022 and that the highest recorded indoor temperature was 41°C on 11 June. The predicted and validated temperature results were similar, with a slight difference of less than 15%. Recycled glass positively and significantly reduced the indoor temperature in summer by 10.2% and thermal amplitude by 48.3%, with a time lag increase of 100% and an increase in the period of comfort hours of 380%. In winter, the daily average temperature increased by 7.4%, thermal amplitude was reduced by 59.3%, and the time lag increased by 100% in comparison with the baseline case results. The study concludes that recycled glass distribution gives the best improvement compared to straw bale and sheep wool.

A new approach to dynamic forecasting of cavity pressure and temperature throughout the injection molding process

AbstractThe injection molding process is very sensitive to ordinary environmental alterations, as the numerical simulation is limited to within one injection cycle, and it cannot predict transient regimes. The present study presents a new approach based on SARIMAX models developed to predict the temperature and pressure inside the mold cavity. The proposed approach was developed in Python language, and it can identify the behavior of the process, allowing preventive actions. Experimental data of temperature and pressure obtained in real‐time inside an injection mold were accessed to use and to validate the proposed model. The results showed its efficiency and its high accuracy for predicting variations in temperature and pressure inside the mold, even when using a small number of samples to be trained. The proposed model can be very useful for monitoring the production of mechanical parts, under an Industry 4.0 environment. For future works, the model enables a contribution toward digital twins of a molded part, considering all the alteration on the parts' properties due to the disturbance on the injection molding process. Furthermore, it lays the groundwork for a new injection machine control system architecture.

Thermal Characteristics of a Vertical Hydrostatic Guideway System for Precision Milling Machine Applications

This paper investigates the thermal characteristics of a vertical guideway system for precision milling machine applications by considering three heat sources, namely motor heat, viscous shearing heat of hydrostatic bearings, and friction heat from a ballscrew nut. A finite element (FE) model using ANSYS/Fluent was used to simulate the thermal characteristics of the system by considering the oil film friction of the hydrostatic bearings in the operational feed speed and heat generation in the ballscrew nut. Eight K-type thermocouples were installed in the vertical hydrostatic guideway system to measure the temperature rise in the key components. Nine thermal experiments of the vertical hydrostatic guideway system under three operational feed rates, namely 1.25, 2.5 and 5 m/min were conducted to measure the temperature of seven thermocouples in practical running conditions. The experimental temperature data then was used to adjust the FE model setting to guarantee the accurate prediction of the thermal deformation in real operational conditions. The FE model of the vertical hydrostatic guideway system built in this study can be used to predict the thermal deformation of worktable at center point at any running conditions. At a sliding feed rate of 1 m/s, the thermal positioning error of worktable at center point was 0.1539 µm in the X direction, 0.0009 µm in the Y direction and 2.0246 µm in Z direction.

Prediction of 3D natural convection heat transfer characteristics in a shallow enclosure with experimental data

This study presents an inverse computational fluid dynamics (CFD) simulation combined with the least-squares method and overdetermined experimental temperature data to predict the unknown heat transfer rate Qh and three-dimensional (3D) natural convection heat transfer characteristics in a closed shallow enclosure. This novel study belongs to the inverse convection-conduction conjugate heat transfer problem. The results show that the zero-equation turbulence model is more suitable for this study compared to other flow models. Thus, the zero-equation model is chosen as the suitable flow model because its estimates are the closest to the experimental data and existing correlation. An important finding is that, for H/L = 1/15 and Ra = 1820, Bénard convection cells and eight vortices appear in 3D and two-dimensional (2D) temperature contours, respectively. This Ra value is close to the existing critical Rayleigh number of 1708. The arrangement of these cells and vortices can be merged with each other and reorganized as H/L increases. The obtained 2D velocity patterns and air temperature contours agree with existing patterns and isotherms. The obtained h‾hi values also agree well with the existing correlation. Thus, the present results have good accuracy. A review of the literature indicates that a few studies have been conducted on using the inverse method along with overdetermined experimental temperature data to study the present problem.

Numerical investigation on the thermal behavior of cylindrical lithium-ion batteries based on the electrochemical-thermal coupling model

• HET model and LET model are proposed. • Radial temperature gradient of cylindrical LIB is non-negligible. • Inhomogeneous discharge due to non-uniform temperature distribution inside cylindrical LIB is investigated. • This work provides insights to choose appropriate electrochemical-thermal coupling models. In this paper, a one-dimensional electrochemical model and a three-dimensional axisymmetric heat transfer model are coupled to simulate the electrochemical and thermal behavior of cylindrical lithium-ion batteries (LIBs). The model is verified against the experimental data of discharge voltage and surface temperature of LIBs under different discharge rates. First, the holistic electrochemical-thermal coupling (HET) model and the layered electrochemical-thermal coupling (LET) model are established. In contrast to the traditional HET model, the advantage of the LET model is that it can realize the investigation on the inhomogeneous discharge and aging induced by the non-uniform temperature distribution inside the battery. We demonstrate the radially inhomogeneous discharge of cylindrical LIBs with a 4-layer LET model in this work. It is also found that the HET model can provide desirable simulation accuracy in temperature with less computational cost. This provides insights for researchers to choose more appropriate electrochemical-thermal coupling models in accordance with the different scenarios. Second, the thermal behavior of cylindrical LIBs at different discharge rates is studied by analyzing the heat generation rate and heat dissipation characteristics during the discharge process. The study reveals that, unlike pouch LIBs, there is a significant temperature gradient in the radial direction of cylindrical LIBs. Finally, the factors that affect the temperature uniformity of the battery, such as cooling conditions, ambient temperature, discharge rate, radial dimension, and radial thermal conductivity are analyzed in detail. Meanwhile, some suggestions are provided to improve the temperature uniformity. The findings in this work are of benefit to obtain profound understading of thermal behavior in cylindrical LIBs. Besides, they also have potential applications in improving the prediction accuracy of the temperature signal in the battery thermal management system of LIBs.

Numerical simulation of CO emission in a sintering pot under flue gas recirculation

A transient two-dimensional sintering model coupling porous medium flow, interphase heat mass transfer and reactions was established through computational fluid dynamics (CFD) method by Comsol Multiphysics 6.0 for a sintering pot under sintering flue gas recirculation (SFGR). The ignition was considered and CO was the carbon combustion intermediate and experienced catalytic oxidation in the ferric oxide bed. The model was verified by sintering pot experimental data of flue gas temperature and components fractions with maximum deviation less than 10 %. The bed temperature, CO emission and solid fuel consumption were focused under different SFGR parameters by the verified model. Ignition was important for the beginning flue gas component fractions, especially when the bed height was less than 700 mm. The effect of SFGR parameters on the maximum bed temperature (MBT) was sequenced: inlet gas velocity > inlet CO fraction > inlet O2 fraction > inlet gas temperature. MBT grew up when each of the four parameters increased. The impact on the CO emission was different: inlet CO fraction > inlet O2 fraction > inlet gas velocity > inlet gas temperature. CO emission declined when each of the parameters increased. The total reaction rate of CO was studied for explanation. The reduction of solid fuel consumption was studied by energy conservation to evaluate the influence of inlet CO, inlet gas temperature and flue gas recirculation fraction. The three factors had positive linear correlation with solid fuel consumption reduction. The reduction maximally reached 16.6 % at flue gas recirculation fraction of 50 %, inlet 2 % CO and 473.15 K temperature, providing theoretical support for SFGR application.

Analytical Model for Thermoregulation of the Human Body in Contact with a Phase Change Material (PCM) Cooling Vest

Cooling vests containing phase change materials (PCMs) are used to reduce heat stress in hot environments and maintain the body core temperature within a safe range. The performance of such cooling vests depends in a complicated way on the PCM material and mass, the insulation value of the clothing layers and heat loss to the environment. Conventionally, these performance parameters are evaluated experimentally or using a numerical model, both of which do need a certain amount of evaluation time. The objective of this paper is to develop a transient heat transfer model which includes metabolic heat production in the human body, as well as clothing and PCM layers and radiation to the environment but which is presented as a series of closed-form equations that can be evaluated without the need of a numerical solver. We present solutions for the body and PCM temperature as well as for the heat flux, cooling power and cooling duration. The model equations are validated by comparing them with experiments of ice PCM packs on a hotplate, as well as with published experimental and numerical data for the core temperature, heat flux and percentage of environmental heat loss using a Glauber salt type of PCM. Both the hotplate experiments and the model predictions show that the cooling power during PCM melting drops from about 70 to 32 W for increasing insulation layer thicknesses. In addition, the model is seen to compare well with experimental and simulation data in the literature. In a parametric study, we show how the equations can be used to evaluate the effects of PCM melting temperature and PCM thickness on cooling performance. The paper, therefore, can be considered as a practical means to help select the best cooling vest configuration for workers in a hot and humid environment.

Thermal-Hydraulic System-Level Analysis of a Molten Salt Natural Circulation Loop

Molten salt reactors (MSRs) are a class of Generation IV nuclear reactors using molten salts as heat transfer fluids. MSRs bring a number of benefits, including low primary system working pressure, high working temperature, and enhanced safety due to the passive safety systems adopted. Although MSRs promise these benefits, a number of key technology needs, such as the accurate prediction of the thermal-hydraulic performance of the passive safety systems, which completely rely on natural circulation, are indispensable for MSR development, licensing, and future deployment. Therefore, this study develops the one-dimensional (1D) NAtural Circulation COde (NACCO) considering the buoyancy and radiative heat transfer effects in high-temperature molten salts for such predictions. The 1D code, developed using MATLAB, is then benchmarked with experimental data from three natural circulation flow experiments, where water, nitrate salt NaNO3-KNO3 (60–40 wt%), and fluoride salt LiF-BeF2 (66–34 mol%, FLiBe) were used as the working fluids. Our analysis shows that (1) the buoyancy and radiative heat transfer effects need to be considered for high-temperature molten salt natural circulation flows, while the radiative heat transfer effect is negligible for low-temperature water flows in the natural circulation experiments investigated, and (2) the 1D code NACCO predicts salt temperature profiles reasonably well, with less than 18°C and 25°C discrepancies from experimental data for the pipe centerline temperature of NaNO3-KNO3 and FLiBe up to 450°C and 750°C, respectively.

Thermal modeling of directed energy deposition additive manufacturing using graph theory

PurposeThe purpose of this paper is to develop, apply and validate a mesh-free graph theory–based approach for rapid thermal modeling of the directed energy deposition (DED) additive manufacturing (AM) process.Design/methodology/approachIn this study, the authors develop a novel mesh-free graph theory–based approach to predict the thermal history of the DED process. Subsequently, the authors validated the graph theory predicted temperature trends using experimental temperature data for DED of titanium alloy parts (Ti-6Al-4V). Temperature trends were tracked by embedding thermocouples in the substrate. The DED process was simulated using the graph theory approach, and the thermal history predictions were validated based on the data from the thermocouples.FindingsThe temperature trends predicted by the graph theory approach have mean absolute percentage error of approximately 11% and root mean square error of 23°C when compared to the experimental data. Moreover, the graph theory simulation was obtained within 4 min using desktop computing resources, which is less than the build time of 25 min. By comparison, a finite element–based model required 136 min to converge to similar level of error.Research limitations/implicationsThis study uses data from fixed thermocouples when printing thin-wall DED parts. In the future, the authors will incorporate infrared thermal camera data from large parts.Practical implicationsThe DED process is particularly valuable for near-net shape manufacturing, repair and remanufacturing applications. However, DED parts are often afflicted with flaws, such as cracking and distortion. In DED, flaw formation is largely governed by the intensity and spatial distribution of heat in the part during the process, often referred to as the thermal history. Accordingly, fast and accurate thermal models to predict the thermal history are necessary to understand and preclude flaw formation.Originality/valueThis paper presents a new mesh-free computational thermal modeling approach based on graph theory (network science) and applies it to DED. The approach eschews the tedious and computationally demanding meshing aspect of finite element modeling and allows rapid simulation of the thermal history in additive manufacturing. Although the graph theory has been applied to thermal modeling of laser powder bed fusion (LPBF), there are distinct phenomenological differences between DED and LPBF that necessitate substantial modifications to the graph theory approach.

Characterisation of observed heat transfer deterioration modes at supercritical pressure with the aid of a CFD model

The paper analyses experimental data exhibiting heat transfer deterioration phenomena at supercritical pressure resulting in quite different trends of wall temperature. The two modes of deteriorated heat transfer considered here are both due to the laminarisation of flow, owing to lighter fluid appearing at the wall as a consequence of heating. However, in one of the two modes, mainly occurring in the liquid-like region at sufficiently large bulk subcooling with respect to the pseudocritical threshold, after a local deterioration heat transfer is restored almost at normal levels, while in the other, at lower pseudo-subcooling and involving at a larger degree also the gas-like region, a jump of wall temperature to a stable deteriorated condition occurs. In the latter case, the wall temperature finally decreases only when the bulk fluid approaches the pseudocritical temperature, thus causing a smaller density difference between bulk and wall, whose increase was at the root of buoyancy effects leading to deterioration.The two heat transfer deterioration modes are here investigated considering the measured trends of wall temperature in two relevant data sets exhibiting the two behaviours and by the use of a CFD model for predicting detailed data. It is shown that while the first mode of deterioration can be interpreted as an entry-length problem, related to strong buoyancy effects, the second mode is complicated by an excursion to a different manifold of what can be defined as a pseudo-boiling curve, occurring when the imposed heat flux cannot be sustained by normal or enhanced heat transfer. In the latter case, an interesting analogy can be considered with phenomena related to the boiling crisis occurring at subcritical pressures, though the causes of such similar behaviours are obviously quite different. The CFD model, validated by comparison with experimental data of wall temperature, is used as a tool to generalise the observed trends and to draw conclusions.The work is carried out in the frame of studies for assessing and possibly improving heat transfer correlations for supercritical pressure fluids, for the use in the future licensing of supercritical water reactors (SCWRs), in the aim to gain better understanding and to suggest possible modelling strategies. Conclusions are proposed in this regard.

Numerical investigation on transient arc characteristics and anode surface temperature considering the electrode movement

This work investigates the transient anode temperature and plasma parameters considering the electrode movement and the arc expansion. A transient self-consistent model is established using the dynamic mesh approach. Two cases with different maximum arc currents, representing various anode activity, have been studied. The simulations predict significant changes in spatial distribution of species densities, electron temperature and anode surface temperature in case with the anode spot formation. Furthermore, the influence of opening velocity on the plasma parameters has been studied numerically. The model was validated by comparison with experimental data for anode surface temperature as well as spectrally filtered arc images. Results of this comparison are presented and discussed.

Laser-assisted robotic roller forming of an ultrahigh strength martensitic steel

Laser-assisted robotic roller forming (LRRF) was developed as a means for bending ultrahigh strength martensitic steel (MS1300) strip without fracture. The strip is bent through application of a thermal load from a fiber laser followed by a mechanical load from a steel roller: the translational motion of both is controlled via an industrial robot. A combined experimental and computational methodology was developed using a lab-scale LRRF cell and a finite element (FE) model that accounts for thermo-elastic-plastic bending from laser irradiation and the roller contact. The FE model was calibrated according to the experimental temperature data to reconstruct the spatiotemporal temperature field. The simulated temperature field was further applied to analyze MS1300 microstructure evolution and microhardness distribution. It is shown that the material under the laser beam was austenitized and then quickly cooled down. The microstructure in the bend subsequently consisted of new martensite near the tension (irradiated) surface, a through-thickness region consisting of both martensite and tempered martensite, and tempered martensite at the compression side of the bend.

CO2 solubility modelling in Non-Precipitating aqueous solutions of potassium lysinate

Modelling of CO2 solubility in aqueous solutions of potassium lysinate (LysK) is mainly hindered by scarcity of experimental vapor–liquid equilibrium data and lack of chemical equilibrium constants associated to the reaction mechanism for the CO2/LysK/H2O system. Therefore, Kent-Eisenberg (KE) correlation stands out from the literature, being among the most used approaches for the description of the equilibrium CO2 partial pressure at different loadings. In this work, a Kent-Eisenberg-like approach has been developed, enhancing the empirical Kent-Eisenberg with Debye-Hückel activity coefficients in order to guide model calibration with reference to selected experimental data for CO2 solubility in 33.1 and 33.5 %w/w aqueous LysK solution; moreover, the KE edition provides an estimation of the missing equilibrium constants. This information has been embedded in a first thermodynamically sound and predictive Deshmukh-Mather (DM) model (average absolute deviation equal to 7 %) validated against additional experimental data in a wide temperature and concentration range.

Determination of the figurative point trajectory on the phase diagram of NiO lithiation-oxidation process by x-ray diffraction and Compton scattering methods.

The positions of the figurative points on the triangular Gibbs phase diagram for the process of high-temperature synthesis of solid solutions LiyNi2-yO2 were determined for the first time using a combination of x-ray diffraction (XRD) and Compton scattering methods. The trajectory of the figurative point is built according to experimental data for temperatures of 650 and 750 °C. The ratios of the phases in equilibrium are found. It was established that, when the structure goes from rock salt to layered structures, the composition of the reagent mixture changes nonmonotonically: with an increase in the degree of ordering of the solid solution lattice, the sum molecular weight of the solid reagents increases. It has been shown experimentally that the combined use of XRD and Compton scattering makes it possible to carry out physicochemical analysis of the process and predict the final product.

Simulation of an orographic gravity wave above the Amazon rainforest and its influence on gases transport near the surface

The influence of the topography at the ATTO site (Amazon Tall Tower Observatory) in the formation of Gravity Waves (GW) was investigated in this work. The role of these waves in gas transport on different heights in the nocturnal boundary layer, was also investigated. For this, were analyzed: experimental data of wind speed, temperature, humidity and CO2 to identify the GW. Furthermore satellite images, ECMWF ERA5 (European Center for Medium-Range Weather Forecasts) reanalysis, and numerical simulations from the mesoscale JULES-CCATT-BRAMS model (Brazilian Regional Atmospheric Modeling System) version 5.3 were used to perform GW simulations. The simulations involved two configurations (Control-With Topography and No Topography). The sattelite images made it clear that the GW was not associated with convective activities. The simulations showed clear ondulatory signs in air temperature, vertical component of the wind, and gases like CO and O3. Moreover, they also reveal that the wave originated by the presence of the local topography and this orograph gravity wave had and important role in the transport of gases above the ATTO site.

Simultaneous identification of the heat capacity and the anisotropic thermal conductivities of a Li-ion pouch cell by a non-destructive analytical approach

The specifications and aging of Li-ion batteries highly depends on temperature. Battery thermal models are therefore useful to improve the thermal management of battery packs. This study presents a method to determine the heat capacity and the anisotropic thermal conductivities of a Li-ion pouch cell. A single experimental setup is devised and involves local heating of the battery with a resistance heater. The thermal properties of the cell are then identified by calibrating an analytical thermal model with the experimental temperature data. A three-dimensional analytical model is developed for this purpose. It allows for simultaneous characterization of the cell anisotropy. The thermal properties are identified at 50% state of charge between 0 °C and 40 °C. Models with adiabatic and convection boundary conditions are compared and showed similar results. Overall, the values and tendencies agree with the literature. This non-destructive method can be directly applied to any pouch and prismatic cells, and adapted to cylindrical cell.

Investigation of Temperature Variations and Extreme Temperature Differences for the Corrugated Web Steel Beams under Solar Radiation.

Due to the coupling impacts of solar radiation, wind, air temperature and other environmental parameters, the temperature field of steel structures is significantly non-uniform during their construction and service stages. Corrugated web steel beams have gained popularity in structural engineering during the last few decades, while their thermal actions are barely investigated. In this paper, both experimental and numerical investigations were conducted to reveal the non-uniform features and time variation of the corrugated web steel beams under various environmental conditions. The heat-transfer simulation model was established and verified using the experimental temperature data. Both the experiment and simulation results demonstrate that the steel beam has a complicated and non-uniform temperature field. Moreover, 2-year continuous numerical simulations of steel beams’ thermal actions regarding eight different cities were carried out to investigate the long-term temperature variations. Finally, based on the long-term simulation results and extreme value analysis (EVA), the representative values of steel beams’ daily temperature difference with a 50-year return period were determined. The extreme temperature difference of the steel beam in Harbin reached up to 46.9 °C, while the extreme temperature difference in Haikou was 28.8 °C. The extreme temperature difference is highly associated with the steel beam’s location and surrounding climate. Ideally, the outcomes will provide some contributions for the structural design regarding the corrugated web steel beam.