This study benchmarks the predictive performance of commercial multiphase flow simulators for flow assurance in Brazilian pre-salt offshore production facilities (OPFs). A dataset of 350 field measurements from seven OPFs was used to compare ALFAsim and OLGA against the in-house mechanistic model Parque das Baleias (PB), under identical geometry, fluid property, and boundary condition inputs. Steady-state simulations evaluated pressure, temperature, and liquid holdup, while transient cases examined well shut-in and restart operations, including hydrate formation risk. In steady-state analysis, all simulators achieved engineering-level accuracy, with pressure predictions within ±20

This study presents experimental analyses of liquid density and bubble-point pressure for binary mixtures of R-290 and POE ISO 32 lubricating oil between 283.15 and 343.15 K. Using a variable-volume synthetic apparatus, bubble-point pressures were measured for mixtures with R-290 mol fractions ranging from 0.2149 to 0.8140. Only vapor-liquid phase equilibrium (complete miscibility) was observed across all compositions and temperatures investigated. In addition, liquid densities were measured at temperatures between 283.15 and 343.15 K at pressures up to 5 MPa using a vibrating-tube densimeter. The experimental data were correlated using the Patel-Teja-Valderrama (PTV) and Perturbed Chain-Statistical Associating Fluid Theory (PC-SAFT) equations of state (EoS). For the bubble-point pressure calculations, the absolute average relative deviation (AAD) was 3.28% and 6.09% for the PC-SAFT and PTV EoS, respectively. For the density predictions, the corresponding AAD values for the PC-SAFT and PTV EoS were 0.94% and 6.94%, respectively.

Magnetic refrigeration is a promising alternative to traditional vapor compression systems, with potential efficiency and environmental sustainability advantages. However, the narrow operational temperature range of magnetocaloric materials (MCMs) and their reliance on rare-earth elements remain key challenges. Multilayer active magnetic regenerators (AMRs) address the temperature range limitations by combining multiple magnetocaloric layers, each with different Curie temperatures. This study investigates the impact of statistical deviations in Curie temperatures on the performance of multilayer AMRs, specifically using second-order La-Fe-Co-Si materials. A 1D multilayer AMR numerical model is developed to simulate the effects of Curie temperature variability, with radial basis function neural networks employed to efficiently predict performance. The results indicate that although increasing the number of MCM layers enhances cooling power and coefficient of performance (COP), Curie temperature uncertainties significantly degrade the AMR performance. The likelihood of achieving cooling targets diminishes as the number of MCM layers increases, particularly for standard deviations exceeding 1 K. These findings emphasize the importance of accounting for Curie temperature uncertainties in AMR design. Moreover, enhancing the manufacturing precision of the Curie temperatures of MCMs is essential for improving the performance and commercialization of magnetocaloric technology.

This study reports the first investigation of the thermal behavior of compact heat exchangers (HXs) with complex geometries 3D-printed using a photopolymeric composite as the base material. HXs with Triply Periodic Minimal Surface (TPMS) geometry were fabricated using a photopolymeric composite doped with 5 wt% hexagonal boron nitride (h-BN). Mechanical characterization revealed reductions in ultimate tensile strength (41.5%) and ductility (20.5%) compared to the neat resin, whereas hardness remained comparable. Thermal analysis showed an 11.03% increase in thermal conductivity for the composite. Performance testing of the HXs demonstrated a 28.74% improvement in overall thermal conductance and a 26.25% enhancement in heat transfer compared to neat resin heat exchangers. These findings highlight the potential of h-BN-doped photopolymeric composites for fabricating complex structures and advancing thermal management applications.

La(Fe,Si,Mn)(13)H-z are among the most promising magnetocaloric materials (MCMs) used in room-temperature magnetic refrigeration. They exhibit an intense magnetocaloric effect (MCE), a low content of rare-earth elements, and a tunable Curietemperature ( $T_{\mathrm {C}}$ ), the temperature at which the MCE reaches its apex. MCMs are assembled in a porous-layered component called active magnetic regenerator (AMR), where the materials are arranged to achieve a gradient of $T_{\mathrm {C}}$ values. Since the material constantly changes its magnetic state to trigger the giant MCE, it is important to analyze how its properties behave in both ferroand paramagnetic states. Besides that, although commercially available La(Fe,Si,Mn)(13)H-z compounds have been used in several studies in recent years, they cannot achieve the expected performance based on lab-made materials. This work investigates how the thermostructural properties of several batches of commercially available La(Fe,Si,Mn)(13)H-z microspheres, with T-C ranging from 282 to 307 K, vary according to the magnetic state of these materials at its application temperature, the room temperature. X-ray diffraction (XRD) analysis revealed that the magnetic state has a significant influence on the microstructural properties of the MCM. The crystallographic density of the magnetocaloric phase of the materials that were in the ferromagnetic state was about 1% higher than those in the paramagnetic state. Furthermore, the crystallographic results showed that the magnetic state of the magnetocaloric phase also affects the structure of secondary phases present in the material, such as the alpha-Fe, which suffers a 1% density reduction during the magnetic transition of the magnetocaloric phase. Similarly, photoacoustic absorption spectroscopy (PAS) results unveiled that the samples in the ferromagnetic state have higher values of thermal diffusivity, reaching up to 7.9 mm(2)/s, while materials in the paramagnetic state range from 4.5 to 5.5 mm(2)/s. Also, the PAS analysis also highlighted a key difference between commercially available materials and lab-scale compounds, the latter of which have lower values of thermal diffusivity (up to 1.5 mm(2)/s) because of the lack of a conductive secondary phase. The results presented in this article highlight the importance of considering the differences between the properties of commercially available materials and laboratory-made ones and also the fluctuation of thermal and structural properties depending on the material's magnetic state, which are key factors when designing magnetic refrigeration prototypes and simulating their performance.

Traditionally, designing novel materials involves exploring new compositions guided by insights from previous work, relying on a trial-and-error approach, where continuous synthesis and characterization proceed until the properties meet the improvements. This method is inefficient due to the challenges of exploring vast chemical spaces. In this study, a machine-learning-based methodology is developed to assist the design from available data in the literature, allowing us to test in silico more than 1.2 million compositions. Two databases with 1227 inputs were created from published studies. Four machine learning (ML) models were trained over the feature sets using 517 compositional features (generated from 58 atomic properties) to predict magnetocaloric properties of perovskites: Curie temperature (T C), magnetic entropy change (ME), and relative cooling power (RCP). The best model-feature combinations were used to explore the chemical space of lanthanum, praseodymium, and neodymium manganites, identifying composition trends for different temperature applications, including room temperature refrigeration, where the most suitable combinations of doping elements were highlighted. The study offers valuable guidelines for future research insights on magnetocaloric materials, and the methodology can be transferred to other perovskite related material areas, such as catalysts and solar cell materials.

The multi-jet spray cooling unit, integrated with a compact, linear, oil-free R-134a compressor introduced in previous work, is now experimentally evaluated with R-1234yf and R-600a as drop-in replacement alternatives. This unit combines the functions of the evaporator and the expansion device into a single device, allowing the subcooled refrigerant to expand through an array of oblique orifices and form a spray that directly impinges on the heated surface. The experimental analysis quantifies the cooling system thermodynamic performance, including compressor power and coefficient of performance, as well as steady-state heat transfer parameters such as heat transfer coefficient, surface temperature, and critical heat flux. The evaluation considers the influence of refrigerant charge, steady-state applied thermal load (cooling capacity), and refrigerant type. To ensure an unbiased comparison, the refrigerant charge is adjusted so that all refrigerants maintain the same evaporating temperature at the lowest thermal load of 25 W. Experimental tests are conducted across a wide range of evaporation temperatures (4.5 to 20.0 degrees C). The results indicate a trade-off between heat transfer performance and thermodynamic performance of the refrigeration system when selecting a refrigerant alternative. R-600a required the lowest refrigerant charge to achieve the reference evaporation temperature and exhibited the lowest refrigerant mass flow rate under all tested conditions. However, the heat transfer performance of R-600a is severely penalized compared to R-134a and R-1234yf, with approximately a 40% reduction in the maximum heat transfer coefficient. The maximum values of the heat transfer coefficient for R-134a, R-1234yf, and R-600a are 42.9, 43.4, and 25.8 kW/m2 K, respectively.

Magnetocaloric systems are one of the most promising solutions for decarbonizing cooling systems. However, several challenges must be overcome to enable the technology to reach large-scale market adoption, among which the high cost and volume of the systems can be highlighted, mainly caused by the magnetic circuits (MC). Addressing these challenges requires emphasizing the trade-off between augmenting magnetic flux density and reducing the mass and complexity of the MC. This study introduces a topology optimization method focused on crafting an MC that minimizes volume while maximizing magnetic flux density while employing rectangular prismatic permanent magnet segments. The optimized design, exhibits similar volume and magnetic flux density compared to configurations with non-prismatic segments, substantially lowering manufacturing costs and underscoring the potential of topology optimization methods in overcoming key barriers to the large-scale adoption of magnetocaloric systems.

Over the last few years, the attention to the carbon footprint of cooling systems has increased substantially, and along with them the demands for the development of more efficient and greener systems. For that, magnetocaloric refrigeration represents a promising solution despite its low technological maturity. This work presents the main finding on the design, commissioning, and performance evaluation of two magnetocaloric prototypes: a wine cooler and an air conditioner. The results demonstrate that the technology still requires improvements regarding the efficiency, cost, and mass of the systems, and the reliability of materials and components. However, investments in technology are expected to soar over the next years due to pressure from society and regulatory agencies.

The present work proposes a mathematical framework for calculating heat transport and annular pressure buildup (APB) in petroleum wells, taking into account salt creep in uncemented annular segments. To achieve this, we propose a Laplace Transform-based semi-analytic method to calculate transient heat flow in the wellbore. To estimate wellbore closure due to creep, we developed a Finite Element Method (FEM) formulation to handle the three deformation components that affect salt displacement. In addition to the time-dependent creep deformation of the rock, the model initially considers the elastic deformation of the rock due to geomechanical loads and pressure changes in the exposed annulus. The model was compared against field data from a well that contained an 800-m long uncemented second annulus exposed to halite. Regarding APB, considering creep in the salt layer resulted in a 2.55-MPa increase (approximately 15%) in annulus pressure. The thermal expansion of the salt rock did not significantly affect APB but significantly increased the computational cost of the simulations.

La(Fe,Si,Mn)13Hz alloys are promising solid-state refrigerant candidates for room-temperature magnetocaloric refrigeration due to their giant magnetocaloric effect, adjustable Curie temperature (TC) and low rare-earth content. For enhanced efficiency, the magnetocaloric material (MCM) is configured into an active magnetic regenerator (AMR), a porous, layered component with a chemically-tuned TC gradient. The porous structure facilitates heat exchange with a working fluid. It is crucial to preserve the thermomagnetic properties, such as TC and the magnetocaloric effect intensity, during refrigeration cycles. This study conducts a systematic investigation of the stability of three batches of La(Fe,Si,Mn)13Hzmagnetocaloric microparticles, each with different values of TC. The commercially available microparticles (average size about 620 mu m), which simulate AMR applications, underwent a 1-year immersion in deionized water and three water mixtures with corrosion inhibitors: Entek FNE (2 % vol.), ME-1 (5 %. vol.) and ME-3 (5 % vol.). Optical and scanning electron microscopy revealed surface changes within the first week of immersion in water and later in two fluids. The TC shifted towards higher temperatures (up to 13 K) after immersion, especially in water and in the ME-3containing medium. After 40 weeks, the Entek FNE mixture caused some damage to the magnetocaloric materials. The lattice parameter of the La(Fe,Si,Mn)13Hz magnetocaloric phase changed, and magnetic entropy decreased for most aqueous media. Only ME-1 proved effective in preserving magnetocaloric microparticle properties for all TCs over a year, making it a potential candidate for long-term prototypes and commercial products.

Although magnetocaloric cooling is considered a promising long-term alternative to vapor compression, recent prototype developments have not yet made this technology commercially competitive, primarily due to its high energy consumption and lack of cost-effective, long-term mechanically-chemically stable materials. To address the first issue and understand how the efficiency of magnetocaloric systems can be improved, dynamic models can offer valuable insights into their transient operation. This work focuses on the development of an artificial neural network with experimental data to model the dynamic operation of a magnetic refrigeration system. Through a design of experiments approach, we propose excitation signals for the identification experiment, involving five manipulated variables and one selected disturbance as inputs, with the output temperature of the cold manifold and power consumption as the target parameters. We chose a nonlinear autoregressive artificial neural network with exogenous inputs to model the transient operation of the system. The temperature model achieved R2 values of 0.995 and 0.955 for the 1-step and 90-step ahead predictions, respectively. Similarly, the power consumption model achieved R2 values of 0.988 and 0.949 for the 1-step and 90-step ahead predictions, respectively. These performance metrics were evaluated on the test sets that were not used for training the models, highlighting the robustness and accuracy of the models in both short-term and long-term predictions.

This study investigates the performance of a multilayered packed-bed active magnetic regenerator (AMR) using spheroidal particles with first-order magnetocaloric properties. The hydraulic performance is assessed via the interstitial friction factor, showing significant underestimation by the Ergun Equation at high mass flow rates. Coefficient adjustments are made to accurately represent the AMR pressure drop, considering particle nonuniformity and structural components, such as layer mesh dividers. This facilitates the pressure drop modeling and provides a means to check the AMR integrity on a routine basis, without requiring AMR disassembly. The thermal performance, evaluated in terms of the regenerator effectiveness, shows a satisfactory cooling potential for practical applications but emphasizes the need for flow control to prevent effectiveness imbalance between hot and cold flows, crucial for optimal operation. The cooling capacity and maximum temperature span are also evaluated, demonstrating that higher mass flow rates yield higher cooling capacities with lower temperature spans, while lower rates achieve higher spans. Varying the blow fraction shows that regenerators at 50% blow fraction achieve 10% higher cooling capacities than at 37.5%. Increasing operational frequency improves cooling by increasing the number of cycles and reducing losses, resulting in a 15% capacity increase between 0.25 and 0.50 Hz. However, this trend may reverse at higher frequencies beyond the experimental limits. While this study improves the understanding of the hydraulic and thermal performance of packed-bed AMRs, its findings underscore the importance of flow balance and frequency in achieving optimal performance, thus providing insights for future system improvements.

The present article numerically studies the relationship between a heat exchanger's thermal performance and the occurrence of fouling, here represented by the deposition of calcium sulfate (CaSO4) on its surface. For that, a 2D geometry denoting the internal flow of a CaSO4 saturated aqueous solution between two parallel plates is simulated. The flow, which can be laminar or turbulent (k-omega SST model), is promoted by a known pressure difference across the channel, while the CaSO4 fouling is thermally triggered by a heat source in the central part of the channel. The numerical model considers the solution of the conservative equations of mass, momentum, and energy, while the mass transfer rate is determined based on a correlation available in the literature. Two approaches were used to determine the CaSO4 fouling rate: (i) the CaSO4 concentration on the fouling's surface was assumed to be identical to the concentration of the bulk flow, and (ii) the fouling concentration varies spatially, hence requiring the solution of the differential equation for conservation of species. The steady analysis showed that for both approaches, the optimal plate-to-plate spacing that maximizes the thermal performance is similar to the spacing that minimizes the fouling deposition. Finally, the transient analysis, which also considers the effect of the fouling removal rate through shear, shows that deviations might occur between the optimal spacings for maximal thermal performance and minimal deposition, especially for lower pressure drop values.