Search Results (3,558)

The growing need for cooling, combined with the environmental concerns surrounding conventional mechanical vapour compression (MVC) systems, has accelerated research for sustainable cooling solutions driven by low-grade heat. Single-stage dual-bed adsorption chillers (ADCs) using silica gel and water provide a promising approach due to their continuous cooling output, lower complexity, and the use of environmentally safe working fluids. However, limitations in their performance, specifically in the coefficient of performance (COP), cooling capacity (Q_cc), and waste heat recovery efficiency (η_e), necessitate improvement through optimization. This study employs statistically validated regression-based objective functions to optimize ten decision variables using the single Grey Wolf Optimizer (GWO) and its multi-objective variant, Muilti-Objective Grey Wolf Optimization (MOGWO), for a silica gel–water single-stage dual-bed ADC. The results from the single-objective optimization showed a maximum coefficient of performance (COP) of 0.697, cooling capacity (Q_cc) of 20.76 kW, and waste heat recovery efficiency (η_e) of 0.125. The values from the Pareto-optimal solutions for the MOGWO ranged from 0.5123 to 0.6859 for COP, 12.45 to 20.73 kW for Q_cc and 8.24% to 12.48% for η_e, demonstrating superior performance compared to existing benchmarks. A one-at-a-time sensitivity analysis revealed non-linear and non-monotonic impacts of variables, confirming the robustness and physical realism of the MOGWO model. The developed MOGWO framework effectively enhances the performance of the single-stage dual-bed ADC and improves low-grade heat utilization, offering a robust decision-support tool for system design and optimization. Full article

In the light of increasing research into amorphous composites and their applications, as-cast specimens of multicomponent Ti₄₈Zr₁₈V₁₂Cu₅Be₁₇ amorphous composites were prepared via water-cooled copper mold suction casting. Subsequently, the as-cast specimens were subjected to semi-solid isothermal treatment to obtain semi-solid specimens. Taking the semi-solid specimens as the research object, room temperature compressive deformation behavior was investigated by analyzing the shear band characteristics on the side surfaces of the compressed specimens. The evolution of shear bands at various stages of plastic deformation was investigated via scanning electron microscopy (SEM). Additionally, significant work hardening was observed after yielding. Surface deformation morphologies indicate that the work-hardening behavior is associated with plastic deformation, interactions between shear bands, and interactions between shear bands and β-Ti crystals. Experiments have demonstrated that at a specific deformation extent, shear bands preferentially initiate at the crystal–amorphous matrix interface. In the final stage of plastic deformation, shear bands propagate through work-hardened β-Ti crystals into the amorphous matrix, with their propagation retarded by the β-Ti crystals. When shear bands in the amorphous matrix are obstructed by β-Ti crystals and can no longer propagate, some evolve into cracks. These cracks then propagate exponentially, leading to eventual fracturing of the specimens and termination of plastic deformation. The research findings provide a theoretical basis for analyzing the deformation capacities of various amorphous composites. Full article

This study presents a facile approach to fabricate PBAT/PHBV films with superior mechanical and barrier properties by in situ forming ribbon-like lamellae, achieving a PHBV platelet-reinforced PBAT films. The fabrication involves melt blending of PBAT and PHBV, where styrene–methyl methacrylate–glycidyl methacrylate copolymer as a multifunctional reactive compatibilizer (RC) regulates PHBV domain size by forming a branched/cross-linked PBAT-B-PHBV structure. The introduction of a compatibilizer into the PBAT/PHBV system can reduce domain size and improve interfacial adhesion, thereby elevating PBAT’s storage modulus and complex viscosity for optimized blow-molding processability. During blow-molding, biaxial stretching with rapid cooling transforms PHBV sea–island structures into well-aligned ribbon-like lamellae. Notably, when PHBV content is ≤30 wt.%, lamellae form in the PBAT matrix, significantly enhancing both mechanical and barrier properties. The addition of RC reduces the lateral dimensions of PHBV lamellae while increasing PHBV number density. The introduction of 0.2 wt.% RC optimizes lamellar dimensions and density to maximize permeation pathway tortuosity. Ultimately, the lamellae in the PBAT matrix yield remarkable property enhancements: yield strength increased by >600%, elastic modulus by >200%, and water vapor/oxygen transmission rate reduced by ~81% and ~85%, respectively. Full article

The electronics industry has significantly contributed to the development of efficient heat dissipation systems. One widely used technique is pool boiling, a simple method requiring no moving parts or complex structures. It enables the removal of large amounts of heat at relatively low temperature differences. Enhancing pool boiling performance involves increasing the critical heat flux and the heat transfer coefficient, which defines how effectively a surface can transfer heat to a cooling fluid. This method is commonly applied in cooling electronic devices, digital circuits, and power systems. In this study, pool boiling at atmospheric pressure was investigated using copper surfaces. To validate the Rohsenow model used to estimate the maximum bubble departure diameter, a planimetric approach was applied. Measurements included average contact angle (CA), surface tension (σ), and droplet diameter for four working fluids: deionised water, ethanol, Novec-649, and FC-72. For each fluid, at least 15 measurements of CA and σ were conducted using the Young–Laplace model. This study provides a comprehensive analysis of the influence of contact angle and surface tension on nucleate boiling using four different fluids on copper surfaces. The novelty lies in combining high-precision experimental measurements with validation of the Rohsenow model, offering new insights into surface-fluid interactions critical for thermal system performance. Full article

Cemented paste backfill (CPB) gains strength through the hydration of the binder constituent of the CPB, where mix temperature is a key influencing factor. Both rate of strength development and ultimate strength are influenced by the overarching temperature conditions in which the binder hydration occurs. This study investigates the influence of mixing water temperature on the thermal behaviour, hydration kinetics, and microstructural development of CPB using a combination of thermal finite element modelling, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Five CPB mixtures were prepared, with water temperatures ranging from 5 °C to 50 °C, and tested under controlled conditions to isolate the effects of the initial thermal input. Results show that moderate mixing water temperatures (20–35 °C) optimize hydration and mechanical strength, while excessive temperatures (≥50 °C) increase the risk of thermal cracking due to generation of excessive heat. The thermal modelling results demonstrated that the highest temperatures were observed in the bottom section of the fill mass, in contact with the surrounding rock, where the combined effects of mix-generated heat and rock conduction were most pronounced. The 50 °C mix reached a peak internal temperature of 85.6 °C with a thermal gradient of 40.5 °C, while the 5 °C mix recorded a much lower peak of 55.7 °C and a gradient of 16.8 °C. These results highlight that higher mixing water temperatures accelerate early hydration reactions and significantly influence the internal thermal profile during the first 21 days of curing. Based on these findings, the design of paste plants can be improved by incorporating a heating/cooling system for the mixing water tank—firstly, to ensure the water temperature does not exceed 50 °C and secondly, to maintain water within an optimal temperature range, potentially reducing binder consumption. Full article

A form of long-term hydrogen storage with high volume efficiency is hydrogen absorption into the host lattice of a metal or an alloy. Unlike high-pressure hydrogen storage, this form of storage is characterised by a low operating pressure. By employing metal hydride (MH) materials in a low-pressure refuelling station, it is possible to significantly increase the safety of hydrogen storage and, at the same time, to facilitate the refuelling of external devices that use MH storage tanks without the necessity of using a compressor. In this article, a methodology for the identification of the mathematical correlations among the hydrogen pressure in the storage tank, the hydrogen concentration in the alloy and the volumetric flow rate of hydrogen is described. This methodology may be used to identify the kinetics of the process and to create simplified simulations of the hydrogen release from an absorption-based storage tank by applying a finite difference method. The mathematical correlations are based on measurements of hydrogen desorption, during which hydrogen was released from the storage tank at stabilised pressure levels. The resulting mathematical description facilitates the identification of the approximate hydrogen pressure, depending on its flow rate, for a particular MH storage tank, while respecting the complexity of its internal structure, heat transfer and the hydrogen’s passage through a porous powder MH material. The identified mathematical dependence applies to the certified MNTZV-159 storage tank at pressures ranging from 7 to 29.82 bar, with hydrogen concentrations ranging from 0.223 to 1.342%, an input temperature of 59.5 °C and a cooling water flow rate of 4.36 L·min⁻¹. This methodology for the identification of a correlation between the flow rate, pressure and hydrogen concentration applies to this particular type of storage tank, and it depends not only on the alloy used and the quantity of this alloy but also on the internal structure of the heat exchanger. Full article

Resource maps for open-loop ground source heat pump (GSHP) systems were developed based on heating and cooling experiments to identify areas with potential for reduced operational costs. Experiments conducted at a public hall, where groundwater temperatures fluctuate seasonally, clarified the relationships between the coefficient of performance (COP) of a heat pump and three key parameters: groundwater temperature, flow rate, and energy consumption. Multiple regression analysis produced equations for estimating the energy consumption of both the heat pump and the water pump. Results indicate that groundwater temperature influences the COP, increasing it by 0.07969 per °C during heating and decreasing it by 0.1721 per °C during cooling. These equations enable the estimation of energy consumption in open-loop systems from groundwater temperature, groundwater depth, and building type. Resource maps developed for the Nobi Plain in central Japan reveal that annual energy consumption is lower in the northwestern region, where groundwater temperatures are generally lower, except in marginal zones for hospitals and offices. Full article

Blue hydrogen is a promising low-carbon alternative to conventional fossil fuels. This technology has been garnering increasing attention with many technological advances in recent years, with a particular focus on the deployed materials and process configurations aimed at minimising the cost and CO₂ emissions intensity of the process as well as maximising efficiency. However, less attention is given to the practical aspects of large-scale deployment, with the cooling requirements often being overlooked, especially across multiple locations. In particular, the literature tends to focus on CO₂ emissions intensity of blue hydrogen production processes, with other environmental impacts such as water and electrical consumption mostly considered an afterthought. Notably, there is a gap to understand the impact of cooling methods on such environmental metrics, especially with technologies at a lower technology readiness level. Herein, two cooling methods (namely, air-cooling versus water-cooling) have been assessed and cross-compared in terms of their energy impact alongside techno-economics, considering deployment across two specific locations (United Kingdom and Saudi Arabia). A sorption-enhanced steam-methane reforming (SE-SMR) coupled with chemical-looping combustion (CLC) was used as the base process. Deployment of this process in the UK yielded a levelised cost of hydrogen (LCOH) of GBP 2.94/kg H₂ with no significant difference between the prices when using air-cooling and water-cooling, despite the air-cooling approach having a higher electricity consumption. In Saudi Arabia, this process achieved a LCOH of GBP 0.70 and GBP 0.72 /kg H₂ when using air- and water-cooling, respectively, highlighting that in particularly arid regions, air-cooling is a viable approach despite its increased electrical consumption. Furthermore, based on the economic and process performance of the SE-SMR-CLC process, the policy mechanisms and financial incentives that can be implemented have been discussed to further highlight what is required from key stakeholders to ensure effective deployment of blue hydrogen production. Full article

The intensification of urban heat in high-density cities has raised growing concerns for public health, infrastructural resilience, and environmental sustainability. As large-scale, multi-functional open spaces, sports stadiums play an underexplored role in shaping urban thermal patterns. This study investigates the spatial and temporal thermal characteristics of eight representative stadiums in central Shanghai and the Pudong New Area from 2018 to 2023. A dual-framework approach is proposed: the Stadium-based Urban Island Regulation (SUIR) model conceptualizes stadiums as active cooling agents across micro to macro spatial scales, while the Multi-source Thermal Cognition System (MTCS) integrates multi-sensor satellite data—Landsat, MODIS, Sentinel-1/2—with anthropogenic and ecological indicators to diagnose surface temperature dynamics. Remote sensing fusion and machine learning analyses reveal clear intra-stadium thermal heterogeneity: track zones consistently recorded the highest land surface temperatures (up to 37.5 °C), while grass fields exhibited strong cooling effects (as low as 29.8 °C). Buffer analysis shows that cooling effects were most pronounced within 300–500 m, varying with local morphology. A spatial diffusion model further demonstrates that stadiums with large, vegetated buffers or proximity to water bodies exert a broader regional cooling influence. Correlation and Random Forest regression analyses identify the building volume (r = 0.81), NDVI (r = −0.53), nighttime light intensity, and traffic density as key thermal drivers. These findings offer new insight into the role of stadiums in urban heat mitigation and provide practical implications for scale-sensitive, climate-adaptive urban planning strategies. Full article

Pumping station structures are widely employed to supply circulating cooling water systems in nuclear power plants (NPPs) throughout China. Investigating their seismic performance under complex heterogeneous site conditions and load scenarios is paramount to meeting nuclear safety design requirements. This study proposes and implements a novel, efficient, and accurate viscous-spring boundary methodology within the ANSYS 19.1 finite element software to assess the seismic safety of NPP pumping station structures. The Maximum Initial Time-step (MIT) method, based on Newmark’s integration scheme, is employed for nonlinear analysis under coupled static–dynamic excitation. To account for radiation damping in the infinite foundation, a Compact Viscous-Spring (CVs) element is developed. This element aggregates stiffness and damping contributions to interface nodes defined at the outer border of the soil domain. Implementation leverages of ANSYS User Programmable Features (UPFs), and a comprehensive static–dynamic coupled analysis toolkit is developed using APDL scripting and the GUI. Validation via two examples confirms the method’s accuracy and computational efficiency. Finally, a case study applies the technique to an NPP pumping station under actual complex Chinese site conditions. The results demonstrate the method’s capability to provide objective seismic response and stability indices, enabling a more reliable assessment of seismic safety during a Safety Shutdown Earthquake (SSE). Full article

As the demand for efficient heat dissipation in information devices continues to escalate, the heat flux of integrated packaging devices is poised to reach 100 W/cm² universally, rendering microchannel liquid cooling technology a pivotal solution in thermal management. In this work, the microchannel heat sink with spoiler cavities, optimized via field synergy principle, was integrated into the high-power electronics, and its flow and heat transfer performance were experimentally investigated using Al₂O₃-water nanofluid. The results show that the experimental and simulation results of the optimized microchannel heat sink integrated with IGBT devices are in good agreement. With structural optimization combined with an appropriate volume fraction of nanofluid, the microchannel heat sink exhibited significantly better heat dissipation performance than that of rectangular heat sinks under a heat flux of 100 W/cm². Furthermore, when the volumetric flow rate exceeded 0.6 mL/s, the heat transfer performance was improved by 38% compared to the rectangular microchannel heat sink with 1% volume fraction of Al₂O₃-water nanofluid. Full article

Recently, plastic and agricultural waste have gained attention as sustainable alternatives. Despite efforts to recycle these materials, much still ends up in landfills, raising environmental concerns. To optimize their potential, these wastes ought to be transformed into value-added products for diverse industrial applications. This work focused on producing thin composite material films using olive oil solid waste called JEFT and recycled plastic bottles. JEFT was cleaned, dried, and processed mechanically via ball milling to produce nano- and micron-sized particles. Composite films were produced via melt compounding and compression molding with a rapid cooling process for controlled crystallinity and enhanced flexibility. Their density, water absorption, tensile strength, thermal stability, water permeability, functional groups, and biodegradation were comprehensively analyzed. Results indicated that 50% JEFT in recycled plastic accelerated thermal deterioration (42.7%) and biodegradation (13.4% over 60 days), highlighting JEFT’s role in decomposition. Peak tensile strength (≈32 MPa) occurred at 5% JEFT, decreasing at higher concentrations due to agglomeration. Water absorption and permeability slightly increased with JEFT content, with only a 1% rise in water permeability for 50% JEFT composites after 60 days. JEFT maintained the recycled plastic’s surface chemistry, ensuring stability. The findings of this study suggest that JEFT/r-HDPE films show potential as greenhouse coverings, enhancing crop production and water efficiency while improving plastic biodegradation, offering a sustainable waste management solution. Full article

This study investigates the effects of varying filler content on the thermal and mechanical performance of metakaolinite-based geopolymer composites designed for thermal energy storage applications. The composites were formulated using a geopolymer binder, combined with a thermally stable filler (ground chamotte) and a thermal energy storage filler (waste steel chips) in different proportions. Chamotte content within the binder matrix (binder + chamotte) ranged from 20 to 40 wt.%, while steel chip content varied from 0 to 40 wt.% of the total composite mass. The thermal properties of the composites were evaluated at room temperature and compared with conventional reference materials, including Ultraboard, chamotte brick, and magnetite brick. Mechanical performance, specifically flexural and compressive strength, was evaluated at room temperature and after exposure to elevated temperatures (800 and 1100 °C), followed by two cooling regimes, slow furnace cooling and rapid water quenching. Microstructural characterization via optical microscopy was used to examine filler dispersion and matrix–filler interactions. The results showed that the thermal effusivity of the optimized composites exceeded that of chamotte brick by more than 50%. The highest flexural (12.68 MPa) and compressive (86.18 MPa) strengths were achieved in the composite containing 20 wt.% steel chips, prior to thermal exposure. Microstructural observations revealed the diverse geometry of the steel chips and arrangement of the chamotte particles. These findings highlight the potential of incorporating metallic waste materials into geopolymer systems to develop multifunctional composites with improved thermal storage capacity and mechanical resilience. Full article

This study analyzes the dynamics of temperature and moisture in a cylindrical silo with a conical roof and floor used for storing corn in the Bajío region of Mexico, considering conditions both with and without aeration. The model incorporates external temperature fluctuations, solar radiation, grain moisture equilibrium with air humidity through the sorption isotherm (water activity), and grain respiration to simulate real storage conditions. The model is based on continuity, momentum, energy, and moisture conservation equations in porous media. This model was solved using the finite element method (FEM) to evaluate temperature and interstitial humidity variations during January and May, representing cold and warm environmental conditions, respectively. The simulations show that, without aeration, grain temperature progressively accumulates in the center and bottom region of the silo, reaching critical values for safe storage. In January, the low ambient temperature favors the natural dissipation of heat. In contrast, in May, the combination of high ambient temperatures and solar radiation intensifies thermal accumulation, increasing the risk of grain deterioration. However, implementing aeration periods allowed for a reduction in the silo’s internal temperature, achieving more homogeneous cooling and reducing the threats of mold and insect proliferation. For January, an airflow rate of 0.15 m³/(min·ton) was optimal for maintaining the temperature within the safe storage range (≤17 °C). In contrast, in May, neither this airflow rate nor the accumulation of 120 h of aeration was sufficient to achieve optimal storage temperatures. This indicates that, under warm conditions, the aeration strategy needs to be reconsidered, assessing whether a higher airflow rate, longer periods, or a combination of both could improve heat dissipation. The results also show that interstitial relative humidity remains stable with nocturnal aeration, minimizing moisture absorption in January and preventing excessive drying in May. However, it was identified that aeration period management must be adaptive, taking environmental conditions into account to avoid issues such as re-wetting or excessive grain drying. Full article

Indirect evaporative coolers (IECs) are becoming a viable alternative to the more energy-intensive traditional HVAC systems for space cooling, especially in arid regions. In this work, a recently developed computational model of an IEC was used to conduct a parametric study. The model employs a spray dryer model to track the flow path and evaporation rate of droplets. The key parameters investigated were the temperature of the droplets, a bypass effect where the amount of exhaust air and water was reduced to as low as 10%, and the length of the heat exchanger. The results suggest that the wet bulb efficiency could be increased from the previously observed 35% to 72.5% if the water temperature is decreased to 16 °C. In order to drastically increase the performance, the heat exchanger length should be increased from 50 cm to 100 cm, which could still end up in a more compact design overall as fewer plates are required. The bypass study resulted in peak performance when 40% of the secondary air flow was used as working air in conjunction with a proportional reduction in water usage. Overall, the computational model has been employed in an attempt to reduce the bulkiness, increase the efficiency and reduce the water consumption of such a system. Full article