Thermal Integration Research Articles

Heat Distribution Simulation in a Square Aluminum 7075 Plate Using Laplace Equation and MATLAB

The efficient management of heat transfer from aircraft engines to the wings is vital for maintaining thermal efficiency and structural integrity in modern aircraft design. Excessive heating of the wings, caused by engine-generated heat, can negatively impact aerodynamic performance and safety. This study focuses on analyzing heat distribution in a square aluminum 7075 plate to better understand heat transfer mechanisms. Using the Laplace equation, implemented through MATLAB (2023 Online Version), we aim to simulate and analyze heat distribution on the plate. The numerical method employed in this research involves solving the Laplace equation with Neumann boundary conditions, which represent insulated edges. The Liebmann method is used to iteratively reduce error to less than 1%. Simulations are conducted on an aluminum 7075 plate of dimensions 4x10⁻² m x 4x10⁻² m under various temperature conditions at the edges. Numerical results show that at the 9th iteration, the error reaches 0.71%, while MATLAB simulations yield an error of 0.4681% at the same iteration. The heat distribution across the plate is clearly visualized, and the analysis indicates that increasing the number of grids improves both the clarity and accuracy of the simulation results. In conclusion, this study demonstrates that applying the Laplace equation via MATLAB is an effective approach for analyzing heat distribution in aluminum 7075 plates. The results show that a finer grid resolution enhances accuracy, with a 101-grid system providing particularly clear and precise heat distribution patterns. These findings contribute to the optimization of thermal system designs, especially in aviation-related applications.

Online ultrasonic monitoring of FDM nozzle temperature based on metamaterial buffer rod

Abstract Fused deposition modeling (FDM) has been widely used for fabricating parts with complex geometries. However, during the printing process the nozzle temperature fluctuates which may cause nozzle blockage, inter-filament delamination, over-melting, etc. Therefore, it is of significance to develop an online and in-situ nozzle monitoring system which could overcome such drawbacks for quality assurance. In this work, a multifunctional system is designed by incorporating a traditional ultrasonic probe and a metamaterial buffer rod to online monitor the nozzle temperature and ensure a correct extrusion force and speed. A parametric simulation model is first constructed implicitly based on thermal-acoustic metamaterial structures for the buffer rod. Secondly, since the high-fidelity calculation is computationally expensive, an efficient surrogate model with kriging approach is constructed based on the dataset drawn from limited trials for rapid prediction. Thirdly, multidisciplinary optimization is performed by the NSGA-III algorithm considering the thermal insulation performance, ultrasonic attenuation and structure integrity. The rod is fabricated according to the best parameters decided. A cross-correlation algorithm is calibrated with thermocouple measurement after waveform recording at different temperatures. The online and in-situ temperature measurement can be realized during 3D printing successfully eventually. This will help to improve the printing quality with potential feedback strategies.

Investigating the influence of uncertainty on office building energy simulation through occupant-centric control and thermal comfort integration

Buildings with occupant-centric control (OCC) systems can adjust heating, ventilation, and air conditioning (HVAC) operations based on occupant status to minimize unnecessary energy use. However, because occupant behavior is stochastic rather than constant, and preferred setpoints can vary across occupant groups, this randomness significantly impacts energy use in buildings with OCC systems.This study used a stochastic simulation approach to model the uncertainty inherent in occupancy patterns and evaluate its impact on the energy consumption of an office building with OCC. In this case, the setpoint temperature was determined based on the Predicted Mean Vote (PMV) method so that each zone could be controlled to the preferred temperature according to the occupant group.The results showed that the uncertainty of the annualized sum of electricity consumption for heating and cooling was 4.3 % and 1.8 %, respectively, with 95 % confidence intervals. Notably, a negative correlation was observed between the number of occupants and the uncertainty of energy consumption. Thus, as the uncertainty in the setpoint temperature increased during periods of low occupancy, the uncertainty in the energy consumption of the HVAC system also tended to increase. These insights underscore the significant influence of occupancy-related factors on building energy utilization.

Thermal and energy efficiency in 3D-printed buildings: Review of geometric design, materials and printing processes

Applying 3D printing in construction is a promising, sustainable alternative to conventional methods. However, the thermal and energy performance of 3D-printed buildings remains underexplored, particularly regarding the interactions between geometric design, material selection, and printing parameters. This review addresses this gap by critically examining how the main steps of the printing process impact the thermal efficiency of 3D-printed buildings. Key findings indicate that material development needs to focus on mixes that balance thermal properties,printability,and structural integrity. The review demonstrates how optimising wall cross-sections and cavity shapes can reduce thermal conductivity and enhance energy efficiency. Innovative geometric designs, such as cellular and honeycomb structures, have shown improvements in thermal insulation. Optimising printing parameters, such as extrusion rate and nozzle travel speed, is crucial to minimising thermal bridges and reducing material anisotropy. Advanced numerical models, validated by experimental data and incorporating factors like inhomogeneous porosity, anisotropy, and surface roughness, are essential for accurately predicting the thermal behaviour of 3D-printed structures. The review underscores the need for large-scale, long-term performance studies of 3D-printed buildings under diverse climatic conditions. Additionally, developing standardised fabrication protocols and testing methods is essential for ensuring consistent quality and broader adoption. Addressing these research gaps is crucial to fully realising the potential of 3D printing in sustainable construction and accelerating the adoption of additive manufacturing in the construction sector.

Enhanced thermally integrated Carnot battery using low-GWP working fluid pair: Multi-aspect analysis and multi-scale optimization

Thermally integrated Carnot battery (TICB) emerges as a promising technology for long-duration energy storage. This study aims to improve its multi-dimensional performance from the optimization design level, thereby promoting its competitiveness. Firstly, a refined system architecture is developed, integrating subsystem layout modification and advanced thermal integration mode. Sixteen potential working fluid pairs are formed by screening low-GWP refrigerants as drop-in substitutes for R245fa. Then, a comprehensive evaluation framework is established to characterize this technology from energy, exergy, and economic perspectives, and a collaborative optimization method is introduced to facilitate integrated optimization. Finally, a whole cycle cumulative exergy analysis is conducted to explore directions for further improvement. Results indicate that, compared to the basic architecture, the round-trip efficiency (RTE) of the proposed system is elevated by over 30%. The use of different alternative refrigerants in the charging and discharging cycles makes the TICB not only sustainable but also more efficient. The thermodynamic dilemma of determining the heat pump evaporation temperature disappears with a closed-type heat source. To maximize overall thermo-economics, sufficient heat pump subcooling and evaporator internal superheat are necessary, and the ideal storage temperature span and pinch point temperature difference of heat exchangers must be identified. The collaborative optimization displays that the first-rank working fluid pair is R1234ze(Z)-R1224yd(Z), with an RTE of 85.2%, a volumetric energy density of 3.10 kWh/m3, and a levelized cost of storage of 0.303 $/kWh, respectively. Furthermore, the RTE is highly sensitive to the insulation quality of storage tanks. A mere 2.5% performance degradation can lead to a 10% points decline in RTE. Internal exergy destruction is primarily caused by poor heat transfer matching, while external exergy loss mainly results from underutilized heat sources during non-charging periods. Therefore, we recommend the district heating network as the target heat source for the dual-period TICB. These achievements offer a valuable reference for the research and development of efficient, affordable, and sustainable TICB.

(Invited) Comparing and Contrasting the Advantages and Challenges of Catalysts for Low Temperature AEM, AEL, and PEM Electrolysis

Electrolysis has been promoted as a critical route to enabling green hydrogen and a broader US Department of Energy supported H2@Scale vision enabling a clean, economic and sustainable energy system.1 Low temperature electrolysis offers advantages over high temperature electrolysis in high temperature materials challenges, limited intermittency capabilities, thermal integration, lower manufacturing and technology readiness, steam conversion and separation challenges.2 Within low temperature electrolysis anion exchange membrane (AEM), (liquid) alkaline (AEL) and proton exchange membrane (PEM) electrolysis are the three primary electrolysis technologies being investigated.These electrolysis environments are different and the catalyst materials they employ, and the cost, natural abundance, performance, and durability limitations are all different. These factors have a significant impact on the research focus and needs for each of these competing technologies. This presentation will explore catalysis in each one of these systems and compare critical limitations of each.The PEM system depends on Ir for anode (OER) catalysis. Ir is expensive and one of the least abundant elements in the earth’s crust. While earth abundance of Ir may is a potential concern for projections of electrolysis needs,3,4 the ability to thrift Ir more efficiently and achieve improved durability are critical for achieving hydrogen cost targets. Specific features impacting the cost, performance and durability trade-offs of Ir in PEM electrolysis will be discussed in terms of hydrogen levelized costs and the research advances necessary to have a positive impact on PEM electrolyzers.AEM and AEL electrolysis are distinct in terms of the concentration of supporting (KOH) electrolytes being investigated and the types of electrodes typically employed. AEM electrolyzers typically work at 1M KOH concentrations or below and employ thin film electrodes with alkaline ionomer as a parallel to most PEM designs. AEL electrolyzers typically operate at high (30 wt% KOH) concentrations and consist of electrodes deposited onto metal substrates rather than deposited as a thin film onto the membrane/separator. The materials sets and some of the performance and durability challenges of each of these systems are similar. They also have challenges at both the anode and cathode, where as PEM cathodes operate highly efficiently and durably with low loadings of Pt. The primary advantage of alkaline systems is the ability to enable highly earth abundant electrocatalysis, but challenges remain for performance and durability tradeoffs. These aspects as well as their implications for hydrogen levelized cost will be presented along with target research needs. https://www.energy.gov/eere/fuelcells/h2scale.Alex Badgett, Mark Ruth, Bryan Pivovar, “Economic considerations for hydrogen production with a focus on polymer electrolyte membrane electrolysis,” Electrochemical Power Sources: Fundamentals, Systems, and Applications, 2022, 327-364.Cortney Mittelsteadt, Esben Sorensen, and Qingying Jia, Ir Strangelove, or How to Learn to Stop Worrying and Love the PEM Water Electrolysis Energy Fuels 2023, 37, 17, 12558–12569.Mark Clapp, Christopher M. Zalitis, Margery Ryan, Perspectives on current and future iridium demand and iridium oxide catalysts for PEM water electrolysis, Catalysis Today 420 (2023) 114140.

Preparation of thermally conductive polyimide/aluminum oxide/boehmite composite separators for enhancing lithium‐ion battery safety and performance

AbstractThis study endeavors to enhance the safety of lithium‐ion batteries (LIBs) by synthesizing a polyamide acid (PAA)/Al2O3 composite spinning solution using 4,4′‐diaminodiphenyl ether (ODA) and pyromellitic anhydride (PMDA) as monomers, and nano‐Al2O3 as a thermal conductivity filler. Subsequently, the PAA/Al2O3 fiber membrane is fabricated via electrostatic spinning, followed by gradient heating imidization to produce a polyimide (PI)/Al2O3 composite membrane. This membrane is then dipped into a boron nitride (BM) slurry to ultimately yield an organic–inorganic PI/Al2O3/BM composite separator with superior flame‐retardant and thermal conductivity properties. The thermal stability, flame retardancy, electrolyte wettability, mechanical integrity, and cycle rate performance of the composite membranes are rigorously evaluated. The results demonstrate that the PI/5% Al2O3/BM composite membrane exhibits the most favorable overall performance, with no shrinkage observed at 200°C and no significant changes after sustained ignition for 10 s. The incorporation of the thermal conductivity Al2O3 filler significantly enhances the heat transfer properties of the composite separator. The room temperature ionic conductivity reaches 2.786 mS cm−1 after electrolyte absorption, and the initial discharge capacity of the assembled battery is 156.28 mAhg−1. Following 100 charge/discharge cycles at 0.2C, the capacity retention rate is 97.7%, and at a discharge rate of 5C, the capacity retention rate is 74.9%.

Thermal integration process for waste heat recovery of SOFC to produce cooling/H2/power/freshwater; cost/thermal/environmental optimization scenarios

High-temperature fuel cells (HT-FCs) indeed hold significant promise for enhancing energy systems' efficiency and environmental sustainability. Consequently, there is growing interest in exploring and developing innovative strategies to optimize the integration of heat recovery processes with HT-FC technology. The current research presents an innovative and environmentally friendly poly-generation unit that integrates advanced subprocesses to generate essential products. These final products include electricity, refrigeration, pure water, and hydrogen. This study signifies a significant step towards sustainable and efficient energy production while meeting diverse needs for different utilities. The design unit incorporates a novel modified dual ejector-based organic flash cycle, reverse osmosis water purification, and a water electrolyzer for hydrogen extraction, all integrated with a high-temperature solid oxide fuel cell. Energy, exergy, economic, and environmental (4E) analysis is conducted to thoroughly evaluate the proposed plan. Furthermore, a comprehensive parametric analysis and sensitivity study are performed to pinpoint the key design parameters of the poly-generation unit. To attain the optimal operational status of the poly-generation unit, a three-objective NSGA-II optimization technique is employed to fine-tune the system's performance within the exergy-cost-environmental framework. This approach aims to strike a balance between maximizing efficiency, minimizing costs, and reducing environmental impact for sustainable operations. In addition, a net present value analysis spanning a 20-year timeframe was conducted to assess the profitability of the devised unit. Based on the findings, it is evident that the sensitivity index of the fuel cell operating temperature carries substantial importance, registering a notable value of 0.60. Additionally, the optimization outcomes reveal the system's enhanced performance metrics: an exergetic efficiency of 41.11 %, a unit cost of 58.96 $/GJ, and a carbon dioxide emission reduction rate of 418 kg/MWh. Also, the unit's payback period is shortened from 11.33 years to 8.817 years. Moreover, it improved the unit's sustainability index and net present value, raising them from 1.544 to 4.98 M$ to 1.66 and 7.38 M$.

Economic/sustainability optimization/analysis of an environmentally friendly trigeneration biomass gasification system using advanced machine learning

The present research presents an innovative thermal integration model for a biomass-based power plant to generate power, coolant, and liquefied hydrogen. This integrated arrangement comprises biomass gasification, gas turbine cycle, organic flash-bi-evaporator refrigeration cycle, multi-effect desalination, solid oxide electrolyzer, and Claude cycle. The selection of an eco-friendly fluid for the electricity-cooling production cycle is conduced relying on a comparative analysis. The subsequent examination evaluates the economic-sustainability performance criteria through sensitivity and contour analyses. The comparative assessment identifies R1234ze(Z) as the most suitable working fluid. Four objective functions are scrutinized, and two optimization scenarios are devised based on a machine learning approach using artificial neural networks and a multi-objective gray wolf optimization technique. In Scenario A, the focused objectives are the total destructed exergy and the cost of producing liquefied hydrogen. Meanwhile, Scenario B integrates the sustainability index and the overall system cost rate as primary criteria. Scenario A exhibits more favorable operational conditions and outcomes than scenario B, showing the objectives mentioned as 9955 kW and 3.25 $/kg, respectively. In this scenario, the sustainability index, the overall investment cost rate, and the net present value are obtained to be 1.74, 236 $/h, and 205 M$, correspondingly.

A novel intermediate heat exchange intensified extractive pressure-swing distillation process for efficiently separating n-hexane-tetrahydrofuran-ethanol

The new intensified strategy can be used in special distillation processes to achieve energy savings. Through analyzing the influence of different extractants and pressure on the separation performance of n-hexane-tetrahydrofuran-ethanol. system, extractive pressure-swing distillation process (EPSD) using dimethyl sulfoxide as extractant was proposed. Multi-objective optimization was performed to definite the best operating parameters of EPSD. Based on the phenomenon that the temperature of high-temperature column top is lower than low-temperature column bottom, making it impossible to perform traditional thermal integration, an intermediate heat exchange intensified process (IHE-EPSD) was developed. The performance influencing factors and heat exchange network of IHE-EPSD were analyzed to obtained the optimal IHE-EPSD process. Three heat integration schemes of the IHE-EPSD were designed to further save energy consumption. Finally, the processes were assessed from economy, energy, environment and exergy. The results indicate that the IHE-EPSD process exhibits excellent separation performance, achieving the efficient separation of n-hexane-tetrahydrofuran-ethanol.

Thermomechanical analysis of tungsten-copper joints for fusion applications using digital image correlation

The European DEMOnstration Fusion Power Plant DEMO represents a significant milestone in the progression towards sustainable fusion energy and a critical phase between ITER and commercial fusion reactors, aiming to demonstrate sustained net positive electricity production. Thanks to its properties, tungsten is a promising material for divertor armor. Coupled with copper alloys as heatsinks, they offer robust thermal management properties to deal with intense thermomechanical loads and irradiation damage. Understanding the thermomechanical behaviour of tungsten-copper joints during their application is then necessary for divertor design.This study presents experimental analysis on tungsten-copper brazed materials subjected to thermomechanical solicitations to simulate mono-block conditions with heat fluxes expected to reach 20 MW/m2 and so to face potential creep-fatigue failure. The experimental tests were coupled with Digital Image Correlation up to 400 °C to analyse the thermomechanical behaviour of these joints, providing insights into their thermal behaviour, structural integrity, damage accumulation, joint failure and identification of strains required for creep-fatigue assessment using design codes.

Fundamental Studies on Fluids-Independent Regenerative Nanocomposite Hydrogels for Fracture Treatments of Conformance Control.

Traditional granular hydrogels showed excellent injectivity, thermal integrity, and efficient remediation of heterogeneous reservoirs. However, granular hydrogels have demonstrated their inability to adapt to fractures due to the lack of sufficient interactions. Herein, we present new nanocomposite hydrogels consisting of cationic nanogelators and anionic granular hydrogels that can chemically in situ reform bulk hydrogels in the fractures. Interestingly, our granular hydrogels showed recross-linking independence on carrying fluids, contrary to prior reported fluid-dependent recross-linking granular hydrogels. The recross-linking of nanogelators and granular hydrogels can be accomplished from room temperature to 130 °C. The nanocomposite hydrogels displayed increased shear elastic moduli compared to pristine anionic granular hydrogels, probably due to the increased covalent cross-links formed by the homogeneous regenerative approach. We found that the granular hydrogels had high salinity tolerance even in the presence of 1000 ppm divalent ions of calcium (Ca2+) since Ca2+ ions often act as the cross-linker for partially hydrolyzed acrylamide-based hydrogels. Overall, we obtained new regenerative nanocomposite hydrogels based on cationic nanogelators and anionic granular hydrogels for fracture treatments.

Computational analysis of carboxymethyl cellulose water-based Casson hybrid nanofluid (Al2O3-CuO) flow past a wedge, cone and plate

The swift advancement of heat transfer technologies can be attributed to the growing need for effective heating and cooling systems in various sectors, including the automotive, chemical, and aerospace industries. This work aims to examine the impact of radiation on the behavior of Casson hybrid nanoparticles (Al2O3-CuO) mixed convective flow in three distinct scenarios. The physical properties of copper oxide (CuO) and aluminum oxide (Al2O3) nanoparticles are utilized when mixed with CMC-water as the solvent. This paper aims to analyze the influence of mixed convective flow on the thermal integrity of hybrid nanoparticles when subjected to a wedge, cone, and plate. The analysis of chemical reactions and the existence of a permeable substance is also incorporated. The partial differential systems are appropriately transformed into a system of ordinary differential equations (ODEs). In addition, the calculation of this system of ODEs is carried out using the analytical technique known as the homotopy analysis approach (HAM). The study examines potential resolutions for flow issues in three distinct configurations: wedge, cone, and plate. A comprehensive examination and record of the impacts of various physical characteristics is carried out. The concepts of wall friction, Nusselt number, and Sherwood number, among others, are explained through the utilization of graphical representations. The porosity and Casson fluid characteristics cause a decrease in the performance of the velocity profile. Hybrid nanofluids have superior heat transfer efficiency compared to conventional nanofluids.

Modulation of multisensory nociceptive neurons in monkey cortical area 7b and behavioral correlates.

Wide-range thermoreceptive neurons (WRT-EN) in monkey cortical area 7b that encoded innocuous and nocuous cutaneous thermal and threatening visuosensory stimulation with high fidelity were studied to identify their multisensory integrative response properties. Emphasis was given to characterizing the spatial and temporal effects of threatening visuosensory input on the thermal stimulus-response properties of these multisensory nociceptive neurons. Threatening visuosensory stimulation was most efficacious in modulating thermal evoked responses when presented as a downward ("looming"), spatially congruent, approaching and closely proximal target in relation to the somatosensory receptive field. Both temporal alignment and misalignment of spatially aligned threatening visual and thermal stimulation significantly increased mean discharge frequencies above those evoked by thermal stimulation alone, particularly at near noxious (43°C) and mildly noxious (45°C) temperatures. The enhanced multisensory discharge frequencies were equivalent to the discharge frequency evoked by overtly noxious thermal stimulation alone at 47°C (monkey pain tolerance threshold). A significant increase in behavioral mean escape frequency with shorter escape latency was evoked by multisensory stimulation at near noxious temperature (43°C), which was equivalent to that evoked by noxious stimulation alone (47°C). The remarkable concordance of elevating both neural discharge and escape frequency from a nonnociceptive and prepain level by near noxious thermal stimulation to a nociceptive and pain level by multisensory visual and near noxious thermal stimulation and integration is an elegantly designed defensive neural mechanism that in effect lowers both nociceptive response and pain thresholds to preemptively engage nocifensive behavior and, consequently, avert impending and actual injurious noxious thermal stimulation.NEW & NOTEWORTHY Multisensory nociceptive neurons in cortical area 7b are engaged in integration of threatening visuosensory and a wide range of innocuous and nocuous somatosensory (thermoreceptive) inputs. The enhancement of neuronal activity and escape behavior in monkey by multisensory integration is consistent and supportive of human psychophysical studies. The spatial features of visuosensory stimulation in peripersonal space in relation to somatic stimulation in personal space are critical to multisensory integration, nociception, nocifensive behavior, and pain.

Harnessing solar power: Innovations in nanofluid-cooled segmented thermoelectric generators for exergy, economic, environmental, and thermo-mechanical excellence

Addressing the imperative need for advancements in thermoelectric generation, this study pioneers an analysis of nanofluid-cooled solar segmented thermoelectric generators with non-uniform cross-sections. Insights into thermal management, structural integrity, and economic efficiency in thermoelectric systems are provided, employing a numerical model that accurately represents thermoelectric effects by accounting for temperature dependencies of semiconductor materials. Through research, exploration of diverse coolant strategies, including TiO2, Fe3O4, Al2O3, and graphene, offers key insights into their impact on cooling dynamics. Findings demonstrate that graphene nanofluid, operating at a flow velocity of 2 m/s, outperforms others, achieving optimal power generation of 221.77 mW and an exergy efficiency of 8.99 %. Additionally, at a concentrated irradiance of 595 kWm−2, graphene leads in environmental benefits, with the highest CO2 savings of 0.38 kgyr−1, and demonstrates economic advantages with a cost-effective dollar per mW value of 3.79×10−6 $mW−1. Furthermore, the study verifies the structural integrity of these systems, with graphene achieving an optimal von Mises stress of 1.35 GPa at a semiconductor height of 0.2 mm. These advancements contribute to environmentally friendly and high-performance generators for sustainable energy solutions, paving the way for future innovations in thermoelectric technology.

Efficacy of almond gum for coacervation with whey protein isolate- optimization, functionality and characterization: A comparison with high-methoxyl pectin

Complex coacervates of whey protein isolate (WPI) and two polysaccharides (almond gum (AG) and high methoxyl pectin (HMP)) under the different pHs (2.5–6.0) and biopolymer mass ratios (1:1–6:1) were prepared to achieve the maximum coacervate yield (CY). The optimum pH and mixing ratio to obtain the maximum CY of WPI-AG (75.93 %) and WPI-HMP (53.0 %) coacervates were 4.3 and 2:1, and 3.5 and 3:1, respectively. Although higher serum layers in emulsions stabilized by WPI-AG/HMP coacervates were detected at the 90 °C, remarkable heat stability under processing temperatures was obtained in ex-situ emulsions with both complex coacervates. Significantly more cold-storage and ionic stabilities were observed for emulsions formulated with WPI-AG than WPI-HMP. Peak shifts in FTIR spectra in the WPI-AG coacervate compared to the individual WPI and AG biopolymers revealed strong electrostatic interactions between these biopolymers. The absence of crystalline peaks for AG and HMP in X-ray diffraction (XRD) spectra confirmed the complexation of AG and HMP with WPI. Thermogravimetric and microstructural analyses showed that porous, loose mesh-like WPI-AG coacervates had superior thermal stability and structural integrity compared to WPI-HMP coacervates and individual biopolymers, which evidenced a more gradual weight loss pattern. WPI-AG coacervates would be promising for efficient emulsion-based delivery systems.

Microencapsulation of green tea polyphenols: Utilizing oat oil and starch-based double emulsions for improved delivery

The stability and bioavailability of green tea polyphenols, crucial for their health benefits, are compromised by environmental sensitivity, limiting their use in functional foods and supplements. This study introduces a novel water-in-oil-in-water double emulsion technique with microwave-assisted extraction, significantly enhancing the stability and bioavailability of these compounds. The primary objective of this study was to assess the effectiveness of several encapsulating agents, such as gum Arabic as control and native and modified starches, in improving encapsulated substances' stability and release control. Native and modified starches were chosen for their outstanding film-forming properties, improving encapsulation efficiency and protecting bioactive compounds from oxidative degradation. The combination of maltodextrin and tapioca starch improved phenolic content retention, giving 46.25 ± 2.63 mg/g in tapioca starch microcapsules (GTTA) and 41.73 ± 3.24 mg/g in gum arabic microcapsules (GTGA). Besides the control, modified starches also had the most potent antioxidant activity, with a 45 % inhibition (inh%) in the DPPH analysis. Oat oil was utilized for its superior viscosity and nutritional profile, boosting emulsion stability and providing the integrity of the encapsulated polyphenols, as indicated by the microcapsules' narrow span index (1.30 ± 0.002). The microcapsules' thermal behavior and structural integrity were confirmed using advanced methods such as Differential Scanning Calorimetry (DSC) and Fourier-Transform Infrared Spectroscopy (FT-IR). This study highlights the critical role of choosing appropriate wall materials and extraction techniques. It sets a new standard for microencapsulation applications in the food industry, paving the way for future innovations.

Study of amorphous alumina coatings for next-generation nuclear reactors: High-temperature in-situ and post-mortem Raman spectroscopy and X-ray diffraction

The present work focuses on the investigation of the thermal stability and structural integrity of amorphous alumina coatings intended for use as protective coatings on cladding tubes in Generation IV nuclear reactors, specifically in the Lead-cooled Fast Reactor (LFR) type. High-temperature Raman spectroscopy and high-temperature X-ray diffraction analyses were carried out up to 1050 °C on a 5 µm coating deposited by the pulsed laser deposition (PLD) technique on a 316L steel substrate. The experiments involved the in-situ examination of structural changes in the material under increasing temperature, along with ex-situ Raman imaging of the surface and cross-section of the coating after thermal treatments of different lengths. As it was expected, the presence of α-alumina was detected with the addition of other polymorphs, γ- and θ-Al2O3, found in the material after longer high-temperature exposure. The use of two structural analysis methods and two lasers excitation wavelengths with Raman spectroscopy allowed us to detect all the mentioned phases despite different mode activity. Alumina analysis was based on the emission spectra, while substrate oxidation products were identified through the structural bands. The experiments depicted a dependence of the phase composition of oxidation products and alumina’s degree of crystallization on the length of the treatment. Nevertheless, the observed structural changes did not occur rapidly, and the coating’s integrity remained intact. Moreover, oxidation signs occurred locally at temperatures exceeding the LFR reactor’s working temperature, confirming the material’s great potential as a protective coating in the operational conditions of LFR nuclear reactors.

Performance enhancement attempts on the photovoltaic/thermal module and the sustainability achievements: A review

Scientists initiated a pursuit of more resilient and long-lasting energy sources due to the continuous deterioration of the environment and the substantial rise in the expense of conventional energy sources. Solar energy is one of the most cost-effective, environmentally friendly, and easily accessible sustainable energy sources. Photovoltaic/thermal (PV/T) solar modules are gaining popularity due to their ability to utilise more solar radiation to generate electric power and heat gain simultaneously. This study reviews recent advancements in PV/T modules, focusing on the dual conversion of solar radiation into electrical and thermal energy. The review highlights significant improvements, such as the use of nanoparticles, bi-fluid circulation, and innovative cooling techniques. The study examined the main categories of PV/T systems, including air-cooled, water-cooled, bi-fluid-cooled, nano-fluid-cooled, and ternary nanofluid-based units. This paper offers an in-depth analysis of various components within PV/T modules, covering aspects such as concepts, materials, and review techniques. However, challenges remain, including the trade-off between thermal and electrical efficiency and integration into existing infrastructure. Despite these limitations, PV/T systems show great potential for contributing to sustainable energy solutions and achieving global sustainable development goals. Future research directions include integrating an artificially intelligent approach for system optimization and expanding hybrid PV/T technologies.

Extended mapping and systematic optimisation of the Carnot battery trilemma for sub-critical cycles with thermal integration

Thermally integrated pumped thermal energy storage (TI-PTES) is a flexibility option to recover low-grade heat and provide overnight storage. Common criteria when designing such systems are the power-to-power efficiency (electricity recovery), the exergy efficiency (combined heat and electricity recovery) and the energy density (storage size). However, these are generally conflicting and multi-criteria optimisation is therefore required. Design guidelines have been proposed for some specific case studies but are still lacking for the remaining wide range of possible integrations. This work therefore presents a systematic multi-criteria analysis of a TI-PTES, consisting of a vapour compression heat pump, a sensible heat storage and an organic Rankine cycle, in an extended integration domain. Results show that the storage temperature levels are key variables, as they directly influence the conflict between the performance of the heat pump and the organic Rankine cycle. Also, the intensity of the conflict between the three criteria increases with the temperature difference between the source and the sink, mainly because of the power-to-power efficiency (the density and the exergy efficiency are much less conflicting with each other). Finally, the relevance of thermal integration in TI-PTES is questioned when it leads to a sharp deterioration in exergy efficiency and density.