bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accuracy in evaluating convective heat transfer coefficient by RANS CFD simulations in a rectangular channel with high aspect ratio and V-shaped ribs
Authors: Corti M , Gramazio P , Fustinoni D , Niro A 
Published: January 2025

Abstract
In the framework of heat transfer enhancement inside channels with ribbed surfaces, V-shaped ribs are placed as the most promising among the standard-shaped ribs. This works aims to present a numerical analysis of heat transfer characteristics for forced convection inside a rectangular channel with high aspect ratio 1:10 equipped with V-shaped ribs. CFD simulations are carried out by means of Reynolds Averaged Navier-Stokes (RANS) equations, working with an air flow inside a narrow rectangular channel 120 mm wide and 840 mm long. V-shaped ribs have square cross section and they have been tested both with the tip of the V pointing downwards both upwards with respect to the channel inlet. For each configuration three different values of dimensionless pitch (10, 20 and 40) have been analysed. Comparisons between numerical and experimental data on convective global heat transfer coefficient and pressure drops are presented, showing very good agreement. Finding a properly working CFD model is useful for authors because this work, together with previous studies on 90° and 60° ribs, aims to be exploited during parametric early design-phases of new heat exchangers.
Computational fluid dynamics simulation of the homogeneous flow regime in a large-scale bubble column
Authors: Varallo N , Besagni G , Mereu R , Inzoli F 
Published: January 2025

Abstract
Bubble column reactors are widely used in various industrial applications, yet their characterisation at both global and local scales remains highly complex. This study presents a CFD Eulerian multi-fluid approach to model the hydrodynamics of large-scale bubble columns, focusing on the homogeneous flow regime. Transient 3D simulations were performed using the commercial software ANSYS Fluent 2023 R2, assuming a fixed mono- or poly-dispersed bubble size distribution to represent the dispersed gas phase. The results were thoroughly analysed and the discrepancies between the numerical results and the experimental data were discussed, highlighting areas for future improvement.
Evaporation of arrays of single-component drops on hydrophobic and hydrophilic surfaces
Authors: Tonini S , Cossali G E 
Published: January 2025

Abstract
The paper focuses on modelling the evaporation of arrays of single-component identical sessile droplets, a phenomenon encountered in various applications. An analytical approach is used and developed to treat ordered and scattered sessile drop arrays of any numerosity. An approximate analytical solution for the vapour field and evaporation fluxes from general arrays of sessile drops on any type of substrate (hydrophobic or hydrophilic) is found by a proper superposition of analytical solutions of single drop fields. Comparison with accurate numerical solutions and available experimental results validates the approach. An analysis of ordered and scattered square arrays from 4 to 49 drops on substrates with contact angles from 30° to 150°, is reported and used to study the dependence of the evaporation screening coefficients on array patterns.
Measurement of thermal diffusivity with a modified Angstrom method
Authors: Piva S 
Published: January 2025

Abstract
A methodology has been developed to measure the thermal diffusivity of high thermal conductivity solid materials. The basic idea traces back to the Ångström method, but the implementation differs in some points. Originally the specimen was free to the environment, here the specimen is thermally insulated to reduce, and control, the effects of natural convection. An appropriate analytical solution is used to calculate temperature distribution. The original two-point approach is replaced by a parameter estimation technique to consider multiple measurement points and reduce the final uncertainty. The methodology is used for a pure copper bar. The results are compared with the data available in the literature. The measured thermal diffusivity is 1.16±0.07·10−4 m2/s while the most reliable data available in the literature is 1.17±0.04·10−4 m2/s. The agreement of the present value with those available in the literature is excellent. This makes the use of this simple analytical approach attractive.
Energy transition audits in industries located in Valencian region
Authors: Cañada-Soriano Mar , Peñalvo-López Elisa , Montagud-Montalvá Carla , Valencia-Salazar Iván 
Published: January 2025

Abstract
The industrial sector is a major global consumer of energy, and meeting Europe’s climate neutrality targets will require a complete transformation of the global energy industry. To this end, Energy Transition Audits (ETAs) provide industries with a comprehensive and tailored action plans to reduce their energy consumption while mitigating the impact of CO2 emissions. In this context, this work presents the first results of an Energy Transition Audit conducted in a Valencian food processing facility within the framework of the European project EnTRAINER- Energy Transition Audits towards Decarbonisation. Starting from the industry baseline in terms of energy consumption and costs and production through a one-year analysis, five improvement actions are proposed and evaluated using the following performance indicators: energy and cost savings along with emissions reduction. Finally, the improvement measures are prioritized based on the company’s emissions reduction targets. Therefore, this innovative approach empowers the industries to monitor their progress towards achieving their decarbonization targets.
Numerical investigation on geometrical parameter effects of metal foams in liquid cooling efficiency of battery thermal management within phase change materials
Authors: Arumugam A , Buonomo B , Nardini S , Plomitallo R E , Manca O 
Published: January 2025

Abstract
The objective of this numerical study is to evaluate the effects of geometrical parameters of a metal foam inserted along with a chosen PCM material on the efficiency of liquid cooling of lithium polymer-based batteries. A three-dimensional model of a lithium manganese dioxide battery module is chosen for the analysis purpose. The analysis is performed by placing the module inside a parallelopiped based arrangement at the centre position, which is cooled by liquid flowing through the tubes by means of convection phenomenon. The tubes placed in the arrangement are assumed at a constant temperature and the entire module is adiabatic in nature. The governing physical equations involved in the analysis are based on the Local Thermal Non-Equilibrium constrains. The numerical model is solved using the finite volume technique using the Ansys-Fluent software. The study involves the analysis of thermal management for different pore density values of metal foam such as 5, 10, 20 and 40 with different C-rates of 0.5 and 1C respectively. The change in the internal resistance of the battery is determined using the Generalized Reduced Gradient technique. The analysis is interpreted by the temperature and liquid fraction profiles of the battery module.
Optimal design of thermal storage in hybrid energy systems: application to a laboratory-scale case study with experimental validation
Authors: Bianco N , Di Somma M , Graditi G , Mongibello L 
Published: January 2025

Abstract
The benefits of thermal storage in hybrid energy systems (HESs) are multiple, being among others the enhancement of flexibility of the network and of the efficiency in the energy resources use, by also reducing the overall cost of the energy system. Choosing the capacity of TSS to minimize the operational cost of the HES is not a trivial task, depending on several variables existing at both supply and demand sides. The contribution of this paper is to present the experimental validation of an innovative optimization model aiming to identify the optimal capacity of TSS in HESs that maximizes the economic performances. The optimization model is based on a mixed-integer linear programming approach and allows determining the optimal hourly operating strategies of the system components as well as the optimal capacity of the TSS, while minimizing the total daily energy costs. The optimized hourly operation schedule of the HES was simulated experimentally by using one of the systems from the TSS laboratory of ENEA Portici Research Center. The experimental results demonstrated the practical applicability of the proposed optimization model. In fact, a good overlap was found between the results obtained from the implementation of the optimization model with those obtained from the experimental simulation, both considering energy and economic data.
Preliminary assessment of a two-phase direct cooling of Lithium-Ion battery pack for e-bike mobility
Authors: Giammichele L , Colarossi D , Falone M , Fioretti F 
Published: January 2025

Abstract
Electric mobility is playing an increasingly central role in emission reduction policies to mitigate climate change effect. During the operation of electric vehicles, the batteries may be subject to high variation of the required current, which can lead to a sudden increase in the cell temperature. If this condition occurs repeatedly, there would be a reduction in battery capacity and useful life, and autonomy reduction of the electric vehicle. In the worst case, this problem can lead to the thermal runaway. Therefore, cooling of electric vehicle propulsion systems is a fundamental issue for the electric mobility development. In this article we propose an innovative cooling system using a dielectric low boiling fluid in which the batteries are directly immersed. The system was tested on an electric bicycle under real operative conditions. A special test bench was realized, consisting of a real electric bicycle, a training roller to simulate the load due to road slope and an external electric motor to simulate the pedaling of the cyclist. The results show a substantial decrease in the temperature of the cells with the proposed cooling system and there was a marked improvement in the temperature uniformity of the cells inside the battery pack.
Preliminary experimental studies on coalescer efficiency for liquid-liquid separation
Authors: Carraretto I M , Scapinello D , Bellini R , Colombo L P M , Molinaroli L , Manzolini G 
Published: January 2025

Abstract
The international organizations have identified both water demand and accessibility as critical challenges with both current and future implications for human well-being. In reason of that due to the growing demand, it is essential to advance the technologies used in freshwater production, focusing on sustainability while maintaining operational efficiency. Within the HORIZON 2020 program, it was thought to integrate the desalination processes with Renewable Energy Sources (RES). The desalination process is based on Forward Osmosis (FO), which uses a membrane to split pure water from seawater by exploiting the osmotic pressure difference between the feed solution (i.e., seawater) and the draw solution (i.e., permeate side). For the process to be effective, a low-cost method for regenerating the diluted draw solution is necessary. Hence, a viable alternative is to deploy a thermo-responsive polymeric draw agent that can be regenerated by the heat power rejected from a CO2 power cycle integrated with a Concentrated Solar Power. To perform the separation, a liquid-liquid separator (i.e., coalescer), mostly deployed in the oil and gas sector, is proposed to split the fresh-water from the polymeric draw solution. Hence, the aim of this work is to preliminarily assess the performances of the coalescer, aiming at the formulation of an experimental efficiency expression. Expression that is function of: (1) temperature at which the regeneration is performed, (2) residence time, and (3) draw concentration in the initial solution. The draw agent used in the experimental campaign is the PAGB2000, a thermo-responsive co-polymer that has a Lower Critical Solution Temperature (LCST) above which the fluid splits in two distinct phases: a polymer-rich (more concentrated), and a polymer-poor (more diluted). From the analysis it results that the coalescer performances strongly increase with both temperature and residence time, indeed efficiency achieves values near to 100%. On the other hand, the performances slightly worsen with increasing the initial draw concentration. Eventually, having an efficiency formulation can both help the design process of the desalination plant and provide an understanding on how much this technology can be applied in context far from the ones it was developed for.
Development of a numerical model of CaCl2 hydration and dehydration reaction for thermochemical energy storage
Authors: Baccega E , Zhang Y , Su Y , Bottarelli M 
Published: January 2025

Abstract
Periodical variations experienced by buildings’ energy demand and supply might be tackled by means of Thermal Energy Storage (TES) systems. Among these, thermochemical heat storage (TCHS) by means of thermochemical material (TCM) is one of the most promising, allowing the greatest energy storage density per unit volume, negligible heat losses and long-term storage. As part of the Horizon Europe project “ECHO”, a preliminary 2D model of the TCHS system was developed with the software COMSOL Multiphysics as a tool to support the real-scale prototype design, anticipating the behaviour of the system, as well as the implementation of the control algorithm. The model was implemented to work in both charge (dehydration) and discharge (hydration) without having to change the reaction kinetics equation from time to time, only based on the instant-by-instant boundary conditions. This ability to switch from hydration to dehydration and vice versa at any time makes it possible to estimate the performance of the TCM even in the event of not being completely hydrated or dehydrated, and also to establish some relationship between the TCM charging and discharging times.
Stability analysis of an anisotropic uniformly heated/cooled porous layer
Authors: Barletta A , Celli M , Brandão P V , Lazzari S , Ghedini E 
Published: January 2025

Abstract
The flow resulting from the combination of forced and natural convection within a horizontal porous layer filled with Newtonian fluid is analyzed. The layer boundaries are subjected to uniform and symmetrical heating/cooling. The porous layer is anisotropic such as the permeability is function of the coordinates, and a fully developed flow occurs in the layer, where the temperature is a function of both spanwise and streamwise directions. The latter steady basic state undergoes the onset of thermal instability for adequate values of the Darcy–Rayleigh number, with the neutral stability condition being heavily influenced by the Péclet number, which is linked to the mass flow rate of the basic state. A streamfunction approach is applied and the normal modes method is employed to investigate the linear stability of the basic state. The system of ordinary differential equations obtained is tackled numerically and the critical values of the governing parameters are studied as functions of the Péclet number and of the permeabilities fraction.
Topology optimization using variable-porosity metal foams: design of conduction paths for cooling a heat generating disc and comparison with tree-shaped architectures
Authors: Bianco N , Fragnito A , Iasiello M , Mauro G M 
Published: January 2025

Abstract
Topology optimization (TO) is a design algorithm providing the optimal material layout within a design domain to minimize/maximize an objective function. In thermal science, for instance, it can be used to optimize the design of heat sinks to minimize thermal compliance, entropy generation, average temperature, etc. Recently, classical TO frameworks have been enhanced in multi-material TO in order to include more materials, thereby enhancing the degrees of freedom of the system, and thus ensuring better thermal performance. This work implements both TO and multi-material TO (MMTO) to address a benchmark heat conduction problem, i.e., the cooling of a circular heat generating volume through heat conduction paths. The heat generation is uniform in the disc, the rim is adiabatic, while the centre is set at a fixed temperature – Dirichlet boundary condition – and serves as heat sink. In TO the choice is between void and high-conductivity material, while in MMTO variable-porosity metal foams are integrated. The interpolation of the materials’ thermal conductivity is conducted via an ordered solid isotropic material penalization (SIMP) algorithm. The distinction between materials is attained by setting different thresholds in the interpolation and projection functions. The dimensionless global thermal resistance and domain average temperature are alternately addressed as objective functions to be minimized at equal weight of the system. The findings unveil that MMTO outperforms TO, which outperforms constructal tree networks, considering in the latter case different configurations of different complexity.
Estimation of flow boiling heat transfer coefficient in enhanced tubes. Benchmark correlations and ANN approach
Authors: Passarelli A F , Mastrullo R , Revellin R , Viscito L , Mauro A W 
Published: January 2025

Abstract
This paper addresses the critical gap in predicting the heat transfer coefficient during flow boiling in enhanced tubes, where the use of conventional correlations and predictive methods developed for smooth surfaces do not usually provide satisfactory results. For such purpose, a comprehensive database was collected from existing literature, including a wide range of operating conditions and enhanced tube geometries from several independent sources. The dataset includes mass flow rates spanning from 50 to 1000 kg/m2s, vapor qualities from the onset of boiling (x=0.0) to the dry-out occurrence and beyond (x=0.99), reduced pressures from 0.05 to 0.80, and tube diameters (measured up to the fin tip) from 0.7 to 11.9 mm, for a total amount of approximately 3000 data points.
Existing flow boiling heat transfer coefficient predictive methods for enhanced tubes were implemented and tested with the present dataset, proving a limited accuracy for most of them mainly in case of testing beyond the specific parameter ranges they were developed for. Extrapolation frequently resulted in statistically poor or even non-physical outcomes. Several artificial neural network models were then developed, according to sensitivity analysis approach to look for potential input parameters and network structures. Specifically, two approaches were employed: a standard neural network model and a correlated informed neural network (CINN), integrating physical correlations into the network’s architecture, thus informing the model with physical principles that govern the heat transfer process. Despite a lower overall accuracy, the correlated informed neural network demonstrated superior reliability than standard one, resulting in an instrument to improve the accuracy of existing correlations.
Two-Phase Pressure Drops Analysis in a Chevron-Type Corrugated Channel Using Image Segmentation for Void Fraction Estimation
Authors: Passoni S , Ferrario A , Mereu R , Inzoli F 
Published: January 2025

Abstract
This study examines the pressure drops and flow patterns in a Chevron-type Compact Plate Heat Exchanger (CPHE) with air-water two-phase mixture under adiabatic conditions. A transparent replica channel, made from epoxy resin, was used to mimic the heat exchanger’s fluid dynamics and allow for optical access. The channel featured a 63° corrugation angle, 2.5 mm depth, and 8.9 mm pitch, yielding a global enlargement factor of 1.17. A particular inlet section was designed to ensure even phase mixing and distribution. Operating conditions varied from 6 to 365 kg/m2s for water and 0.02 to 5 kg/m2s for air, expanding the range of previous studies. High-framerate back-illuminated visualizations provided detailed observations of the flow patterns. Moreover, frame-by-frame void fraction was estimated via HSV video analysis adopting a convolutional neural network (U-Net) to produce binary masks and estimate gas bubble volumes and via a volume-reconstruction algorithm exploiting the pseudo-2D shape of the channel. A novel correlation for Darcy’s friction factor based on Reynolds number was developed for single-phase flow, complemented by an analysis of two-phase pressure drops using a two-phase multiplier correlated with the Lockhart-Martinelli parameter. The incorporation of void fraction data significantly improved their modelling accuracy.
Changes in the role of Pacific decadal oscillation on East Asian winter surface temperature
Authors: Lee Doo Young , Yeh Sang-Wook , Jeong Hyein , Park Hyo-Seok 
Published: January 2025

Abstract
The complex interaction between the Pacific decadal oscillation (PDO) and East Asian winter temperatures remains unclear. This study reveals that since the early 2000s, East Asia has experienced a strengthening of Aleutian low (AL) and Siberian high (SH) during negative PDO phases, leading to an intensified East Asian winter monsoon (EAWM). The increased pressure gradient between the SH and the AL, driven by warming in the western Pacific associated with the negative PDO phase, has significantly contributed to a shift toward cooling in East Asia (105°–150° E, 20°–50° N) since the early 2000s. Observations and model simulations provide evidence that the enhanced tropical convection in the western Pacific under a negative PDO phase has intensified the atmospheric circulations associated with the EAWM since the early 2000s. Understanding these dynamics is crucial for improving winter temperature forecasts in East Asia.
Volume changing symmetries by matrix product operators
Authors: Borsi Márton , Pozsgay Balázs 
Published: January 2025

Abstract
We consider spin chain models with exotic symmetries that change the length of the spin chain. It is known that the XXZ Heisenberg spin chain at the supersymmetric point

Δ
=
−
1

/

2

possesses such a symmetry: it is given by the supersymmetry generators, which change the length of the chain by one unit. We show that volume changing symmetries exist also in other spin chain models, and that they can be constructed using a special tensor network, which is a simple generalization of a Matrix Product Operator (MPO). As examples we consider the folded XXZ model and its perturbations, and also a new hopping model that is defined on constrained Hilbert spaces. We show that the volume changing symmetries are not related to integrability: the symmetries can survive even non-integrable perturbations. We also show that the known supersymmetry generator of the XXZ chain with

Δ
=
−
1

/

2

can also be expressed as a generalized MPO.