bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurements of Heat Transfer in Flowing Granular Media
Authors: Alsharif Mohamed 
Published: September 2024

Abstract
In recent years, there has been an increased interest in the thermal behavior of granular solids because of many relatively new industrial applications. Process industries involving particulate solids being immersed or carried in a “continuous” fluid phase include chemical, petroleum, metallurgical, food, and pharmaceuticals, as well as many fluidized bed operations. An investigation was conducted of the heat transfer characteristics of a variety of flowing particulate solid media. Five different granular materials were studied in a vertical gravity-driven flow through an electrically-heated circular stainless steel tube test section. From measurements of wall temperature distribution, particle bulk inlet temperature, radial temperature distribution of the particle flow at the test section exit, and mass flow rate determination of local and average heat transfer coefficients along the test section were made. The key to this proposed approach lies in the use of proper equations to evaluate the thermophysical properties of the medium in the critical region adjacent to the heat transfer surface, i.e., voidage, density, thermal conductivity, thermal diffusivity, and specific heat. The design and construction of the thermal loop test facility used in this study is described in this paper. Comparison of the experimental results with available experimental data and predictions of various models appearing in the literature were made. Agreement existed with the modified versions of the packet model. However, for correlations based upon and compared with only limited data, agreement was not satisfactory.
Thermal Transport Mechanisms in Lunar Regolith at Low and High Temperatures
Authors: Cao Jiahui , Lee Jaeho 
Published: September 2024

Abstract
Many planetary bodies, such as the Moon, comet, asteroids, and meteoroids, are covered by regolith and exhibit a wide range of temperature variations from daytime to nighttime and across different altitudes. The thermal conductivity of regolith is a critical parameter in determining surface heat flow and temperature variation. In this study, we develop a comprehensive model, combining a semi-empirical approach based on Watson’s equation and an effective medium theory approach based on morphology and mineral composition, to predict the temperature-dependent thermal conductivity of lunar regolith. We study the solid thermal conductivity (ks) induced by the conductive interactions among solid particles and the radiative thermal conductivity (kr) caused by radiative heat transfer through the void spaces in porous media. We find the conductive contribution to be a complex function of morphology, particle size, packing, and the efficiency of contacts between adjacent particles, whereas the radiative contribution strongly depends on the emissivity, particle size, and porosity. More specifically, we estimate the elastic-wave-driven crystalline thermal conductivity (kcr) and the random-walk-driven amorphous thermal conductivity (kam) and evaluate the impact of crystallinity on ks. We further consider the electron contribution to kcr and the radiative influence on kr when metal-rich meteorites are present in the regolith. Considering all the relative contributions to the effective thermal conductivity (keff), we find that keff at low temperatures is dominated by the solid contribution (i.e., ks ∝ [(1 – y)kcr,p + y · kcr,e] + (1 – x)kam) and exhibits substantial variations depending on the degree of crystallinity (x) and metallic composition (y). We observe three distinct thermal transport behaviors for the corresponding solids: (1) kcr,p first increases rapidly to a peak at around 10 K and then decreases monotonically with increasing temperature due to substantial phonon-phonon scattering; (2) kcr,e increases linearly with temperature and reaches a plateau for T &gt; 100 K due to the increase of electronphonon scattering; (3) kam exhibits a unique temperature dependence due to its random walk nature. Furthermore, we find that keff at high temperatures is dominated by the radiative contribution, where kr ∝ T3. This work identifies various thermal transport mechanisms in lunar regolith with respect to microstructures, morphology, composition, and temperature. It provides valuable insights into the fundamental thermophysical properties of regolith concerning future planetary exploration.
Carbon Emission Model of Power Industry Based on Life Cycle Perspective in China
Authors: Zhao Yurong , Dong Yahong , Cheng Hong , Amin Khan Tarip , Li Wei , Mehmood Jasim 
Published: September 2024

Abstract
China is currently the largest carbon emission country in the world. In China, the power industry’s carbon emissions accounted for more than 40% of the total. Moreover, annual electricity consumption is still rising, increasing by 6% to 9.15 trillion kWh in 2023. Therefore, the carbon emission reduction of the power industry is particularly important for achieving the goals of carbon neutrality and carbon peaking in China. From the perspective of the life cycle, the power industry can be divided into three major phases: the generation side, the transmission side, and the consumption side. Starting from these three phases, this paper constructs a life cycle carbon emission model of power systems, incorporating digital monitoring technology to realize the real-time monitoring and management of carbon emissions from power systems in China. On the consumption side, this paper selects the liquor industry in Guizhou as a typical case. It calculates the carbon emissions of some units with a capacity of 6000 kW and above in Guizhou in a month by constructing a carbon emission model. The realization of real-time carbon emission monitoring of the power grid will help the power industry achieve the goal of “dual carbon” at an early date.
Temperature Field Reconstruction of Surfaces Heated Through Radiative Heat Transfer Using Convolutional Neural Networks
Authors: Aldeia Machado Luiz C. , Coppo Leite Victor , Merzari Elia , Wright Lesley , Ibarra Lander , Ponciroli Roberto , Bhat Pramatha , Hassan Yassin 
Published: September 2024

Abstract
Diverse applications require us to know the value of a given physical quantity in real time. For many applications, we can rely on probes to fulfill this task. However, this approach can be challenging when we need to know these quantities in many locations over a given domain due to the spatial limitation involved. In this context, using Convolutional Neural Networks (CNN) can offer a good option to deal with such a problem. A well-trained physics-informed CNN can reconstruct the distribution of a given physical quantity over a domain using only a few sensors, allowing us to reconstruct the desired field distribution even in a limited space or complex geometries where a large array of sensors remains impractical.
In this work, we will present the initial approach to developing a real-time tool for monitoring the thermal behavior of nuclear reactor pressure vessels. Based on an experimental setup, the team developed a computational model using the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework, where the Ray Tracing and Heat conduction modules were used to evaluate the temperature distribution over a convex metal surface heated through radiative heat transfer. This metal surface represents a section of a heated nuclear reactor vessel wall. The team verified our computational model against the available experimental data. Part of the data generated by the MOOSE model was used to train the Convolutional Neural Network to reconstruct the vessel wall’s outer surface temperature. The CNN generalization was then verified against the experimental and computational data. The predicted temperature distribution over the vessel’s outer wall presented an R-square metric of 0.9991 when compared against the MOOSE model.
Heat Transfer Coefficients and Film Cooling Effectiveness on the Endwall of a Transonic Turbine Vane Measured With Binary Pressure Sensitive Paint
Authors: Burdett Timothy A. , Wright Lesley M. 
Published: September 2024

Abstract
Film cooling is a key technique used to reduce heat transfer from hot combustion gases to stationary and rotating components in a gas turbine engine. In high-performance engines, the endwall experiences high heat gains due to flattened mainstream temperature profiles and low solidity ratio airfoils. In this study, the thermal performance of upstream film cooling holes on the endwall of a transonic, five-vane, annular sector cascade was characterized. Transonic measurements of the adiabatic film cooling effectiveness are typically performed with binary pressure sensitive paint (BPSP), which has a reference sensor to allow compensation for temperature variation. A novel experimental technique has been demonstrated that extends the measurement capability of binary pressure-sensitive paint by using the reference sensor to measure the temperature and heat transfer coefficient. These measurements were performed in a transient heat transfer experiment assuming 1D conduction through a semi-infinite solid exposed to a convection boundary. The mainstream exit Mach number was 0.9, and the coolant-to-mainstream density ratio was 1. The coolant-to-mainstream mass flow ratio was varied from 0.75% to 1.25%. An optimum mass flow ratio of 0.75% was identified as it provided the lowest area-averaged heat transfer coefficient while increasing it had little impact on the film cooling effectiveness.
Advancements in Ni-P Plating Surfaces for Mitigating Crystallization Fouling in Microchannel Heat Exchangers
Authors: Sun Jia , Li Wei , Cao Biqi , Zhou Jianxin , Wu Zan 
Published: September 2024

Abstract
In pursuit of sustainable energy solutions and to combat the environmental challenges posed by fouling in thermal devices, this study developed Ni-P-TiO2 and Ni-P-Polytetrafluoroethylene (Ni-P-PTFE) surfaces and explored the effectiveness of coatings in minimizing fouling on heat exchange surfaces. We conducted heat exchange experiments to compare the both coating surfaces with copper surface under identical clean conditions in microchannels. Further analyses explored fouling resistance across surfaces at various flow rates and solution hardness, complemented by Scanning Electron Microscope (SEM) images of fouling morphology. The findings revealed that decreasing surface energy and enhancing hydrophobic properties can reduce crystal fouling. Notably, both Ni-P-TiO2 and Ni-P-PTFE surfaces demonstrated superior performance, showing significantly lower thermal resistance compared to copper surface. Despite the increase in thermal resistance with solution concentration, the growth rate of fouling resistance declined gradually. The Ni-P-PTFE coating, benefiting from its lower surface energy and greater hydrophobicity, showed superior looseness and porosity. This study demonstrates the effectiveness of Ni-P-TiO2 and Ni-P-PTFE coatings in reducing fouling thermal resistance, offering a promising approach for improving microchannel device performance.
Thermal Conductivity of Advanced 3D Printed Polymers
Authors: Jacques Cory , Letcher Todd , Michna Gregory J. 
Published: September 2024

Abstract
Additive manufacturing is increasingly being employed in the production of parts for end-use applications. Fused deposition modeling (FDM) is a type of 3d printing in which a molten thermoplastic is extruded to create the desired geometry. FDM has not been significantly used in heat transfer applications, but if parts with somewhat higher thermal conductivity than is currently obtainable with commonly used FDM polymers (ABS and PLA) can be produced, many potential heat transfer applications could be studied for potential use in real-world applications such as heat exchangers or heatsinks. We have previously presented our work in developing an apparatus for measuring the thermal conductivity of 3d printed materials. In the experimental study presented here, the effective thermal conductivity of many advanced FDM materials is measured using that purpose-built apparatus. The performance of the test apparatus was first validated using a sample of acrylic, a low-conductivity material in which the conductivity is well understood. Next, the thermal conductivities of parts printed from several advanced 3d printing polymer filaments were measured. The filaments tested included natural PLA, as well as composite filaments of aluminum and copper with PLA. The parts produced from composite filaments show a significantly higher thermal conductivity than those using the pure polymer material.
Distributed Single-Mode Optical Fiber High Temperatures Measurements
Authors: Hlifka Brian M. , Kinzel Edward C. 
Published: September 2024

Abstract
This paper investigates the application of single-mode silica optical fibers for capturing distributed high temperatures up to 1100°C. The optical fibers were interrogated with Luna Innovation’s optical backscattering reflectometer (OBR). The Rayleigh backscattering from the inherent inhomogeneities in the core (9 μm) was monitored to characterize the constraints of integrated SM-fiber in high-temperature environments. A relationship between time, temperature, and stress directly impacts a quality factor metric. This metric measurement is based on the degree of autocorrelation between the measured and reference Rayleigh backscattering spectra along its distributed length. Gradual creep of the natural defects in the microstructure occurs at temperatures around 750°C, and the rate of these shifts intensifies with increasing temperature, time, and stress. A continuous high-temperature measurement can be done by defining a new reference, but there is a limited time before introducing noise. This paper will demonstrate the ability of a single-mode optical fiber to temperatures up to 1100°C by defining a new reference Rayleigh spectrum. Also, the viability of an optical fiber is analyzed based on the quality factor, which provides a correlation between temperature and time.
CFD Modeling of End Effects of Gas Cooler Heat Exchanger for sCO2 Power Blocks
Authors: Duggirala Vyas , Hegde Venkata N. , Reddy Venkateswara , Kumar Pramod , Muley Arun 
Published: September 2024

Abstract
Supercritical Carbon dioxide (sCO2) Brayton cycle power blocks provide unique advantages for power generation through flexible operation and highly compact power plants. Gas cooler heat exchangers for sCO2 power blocks are crucial to help maintain ideal conditions at the compressor inlet to maximize net power output and cycle efficiencies. Design, modeling and optimization of these heat exchangers is a challenging task given the proximity of operating conditions to the critical point. Microchannel heat exchanger configurations with repeating unit cell architecture are preferred to attain compact form factors while maximizing the heat transfer rates at reasonably low-pressure drop penalties. The current work investigates the end effects of surface heat loss and bounding walls of heat exchanger stack on thermo-hydraulic performance. A hybrid approach of unit cell CFD modeling coupled with a Thermal Resistance Network (TRN) for estimating complete stack performance is presented under end effects. A compensation strategy to mitigate the variations in pinch temperature is studied under different stack configurations. The findings from the current work indicate that the presence of end effects manifests as variations of channel pinch temperatures leading to flow maldistribution across the heat exchanger stack.
Investigation of Liquid Cooling for Lithium-Based Batteries in Phase Change Materials Using Metal Foams: a Numerical Approach
Authors: Arumugam Aanandsundar , Buonomo Bernardo , Manca Oronzio 
Published: September 2024

Abstract
This study addresses the critical issues of thermal management in electric vehicles focusing on the significant challenges related to the thermal control of rechargeable electric batteries. The optimal temperature maintenance is crucial for sustaining the electric vehicles autonomy by isolating the batteries from external climatic factors and temperature peaks during operation. In this numerical study, a threedimensional cylindrical lithium-polymer based single battery module model is employed. The thermal control process involves the utilization of phase change material (PCM) embedded in metal foam. The battery is further cooled through convective liquid flow facilitated by various tube arrangements. The model is implemented using the finite volume method. Various cases are simulated considering two different PCM’S namely RT25HC and RT 35 embedded with metal foam of two different pore densities of 20 and 40 PPI at three different C-rates of 0.25C, 0.5C and 1C respectively. The study further provides a comprehensive insight into temperature distribution along the surface of the battery during the process of discharge in terms of liquid fraction, maximum surface temperature and the maximum temperature attained by the battery model and the maximum temperature recorded by the PCM materials using the above thermal control arrangement.
Effect of Reactor Configuration on the Performance of a Closed Thermochemical Energy Storage System
Authors: Chate Akshay , Jain Kartik , Dash Susmita , Dutta Pradip 
Published: September 2024

Abstract
Thermochemical energy storage systems (TESS) offer higher volumetric energy density compared to sensible and latent heat storage systems. TESS utilizes endothermic dissociation reaction for thermal energy storage (charging process), and the stored thermal energy is subsequently retrieved by performing a reversible exothermic reaction (discharging process). The reactor of the TESS forms a critical system component as endothermic-exothermic reactions take place in it. The present study focuses on the effect of various reactor configurations on the performance of a potassium carbonate salt hydrate based closed TESS, with the help of numerical studies. The cylindrical and flat type of reactor configurations are commonly used for a closed TESS. The cylindrical reactor configuration offers volumetric compactness but poses challenges such as limited water vapor flow area for penetration into the salt hydrate domain. It is observed that the provision of annular passage for water vapor flow and U-tubes for heat transfer fluid (HTF) flow significantly improve the performance of a cylindrical reactor during the discharging process. Around 69 % of the reactant is consumed by the end of 60 minutes of discharging process with the provision of annular passage for water vapor flow, as opposed to only about 10 % conversion without the provision of the annular passage. On the other hand, a flat reactor configuration provides a larger area for water vapor flow but with higher reactor volume requirement. To reduce the volume requirement, a reactor configuration with multiple stacks of smaller flat reactors is recommended. The addition of metallic fins to the flat reactor results in noticeable improvement. During the discharging process of a flat reactor without fins, complete conversion is achieved in 44 minutes. Whereas in flat reactor with HTF tubes through the salt hydrate domain, complete conversion during the discharging process is achieved within 26 minutes, which is 41 % reduction in the completion time.
Simulation of Time-Domain Thermo-Reflectance Experiments Using the Anisotropic Fourier Heat Conduction Equation and the Phonon Boltzmann Transport Equation
Authors: Saurav Siddharth , Mazumder Sandip 
Published: September 2024

Abstract
The anisotropic Fourier Heat Conduction Equation (FHCE) and the multidimensional phonon Boltzmann Transport Equation (BTE) were solved numerically in cylindrical coordinates and in time domain to simulate a Time Domain Thermo-Reflectance (TDTR) experimental silicon/aluminum substrate/transducer setup. The out-of-phase response of the probe laser was predicted at various beam offset distances for a pump laser pulse frequency of 80 MHz and modulation frequency of 10 MHz and compared against experimental measurements. The isotropic FHCE was also solved for comparison. Results show that the isotropic FHCE with bulk thermal conductivity of 145 W/m/K significantly underpredicts the out-of-phase temperature difference, particularly at smaller beam offsets. With an isotropic thermal conductivity of 105 W/m/K, the computed results match experimental data at smaller beam offsets well, but overpredicts the experimental data at larger beam offsets. An almost-perfect match is obtained by using an anisotropic thermal conductivity wherein the radial (in-plane) thermal conductivity is set to 90 W/m/K and the axial (through-plane) conductivity is set to 130 W/m/K. The multidimensional frequency and polarization dependent phonon BTE is next solved. The BTE results for the out-of-phase temperature difference match experimental observations well at small and intermediate beam offsets, but overpredicts the experimental data at larger beam offsets. FHCE results are fitted to the BTE predictions, and the extracted (best fit) thermal conductivity is found to be 105 W/m/K.
Assessment of Optimal Fin Structure and Shroud Size in Fan-Cooled Heat Sinks for Next-Generation EV Battery Chargers
Authors: Najafpour Sahand , Botting Chris , Bahrami Majid 
Published: September 2024

Abstract
As next-generation battery chargers become more compact yet offer higher power outputs, efficient cooling methods are crucial. Air-cooled heat sinks are gaining prominence due to the growing demand for high-performance EV battery chargers. This study delves into the impact of shroud size and optimal fin configuration in the axial fan impingement cooling technique. Experimental study is performed on the Delta-Q XV3300 battery charger, with four distinct configurations tested, reflective of current market trends: i) no shroud, ii) half-size shroud, iii) full shroud, and iv) a Delta-Q production shroud. Results indicate that the shroud size has negligible effect on the heat sink’s thermal performance, with shrouds directing airflow through the fin array, resulting in up to a 5% temperature decrease on the heat sink’s periphery, in contrast to the no-shroud scenario. Notably, the Delta-Q production shroud lagged in performance, primarily due to its integrated “fan guards.” Furthermore, a numerical model is developed to compare various fin arrangements under the fan, namely bare fin, pin fin, and vane-shaped designs—. Under assumptions of a level heatsink skyline and a uniform heat flux boundary condition, both pin fin and vane-shaped designs surpass the bare fin configuration in thermal efficiency by 7.3% and 5.1%, respectively. At the end, a new heatsink design is provided for enhancing the cooling efficiency, especially when a protective wall shields the connectors. The proposed design introduces an additional wall on the opposite side to curb excessive airflow escape. Additionally, integrating converging radial fins that gradually transition to parallel orientations reduces air circulation, thereby decreasing temperature variances by 7% to 25% across various heat-intensive regions, respectively.