Search Results (304)

The energy requirements for conditioning spaces have been increasing primarily due to population growth and climate change. This paper shows a comparison between an adsorption (ADC) and absorption cooling (ABC) systems to keep a building below the 25 °C set-point in dynamic conditions, utilizing a latent heat storage tank with MgCl₂·6H₂O and erythritol, and employing evacuated tube and parabolic trough collectors. The storage tank geometry is a plate heat exchanger. An auxiliary system was incorporated to control the temperature range of the solar cooling systems. The results showed that the coefficient of performance was kept around 0.40–0.60 and 0.70 for adsorption and absorption cooling, respectively. The latent heat storage tank with erythritol captured more solar energy than MgCl₂·6H₂O. A maximum solar fraction of 0.96 was obtained with MgCl₂·6H₂O, a thickness of 0.15 m, 20 m² of parabolic trough collector area, and absorption cooling, while the energy supply was fully satisfied with a solar collector with erythritol, a thickness of 0.1 m, 13 m² of parabolic trough area, and absorption cooling. In general, erythritol obtained better results of solar collector fractions than MCHH; however, it has less thermal stability than MgCl₂·6H₂O, and the cost is higher. Full article

Negative Ion Source Neutral beam Injection (NNBI), as a critical auxiliary heating system for magnetic confinement fusion devices, directly affects the plasma heating efficiency of tokamak devices through the reliability of its beam source system. The single-shot experiment constitutes a significant experimental program for NNBI. This study addresses the frequent equipment failures encountered by the NNBI beam source system during a cycle of experiments, employing fault tree analysis (FTA) to conduct a systematic reliability assessment. Utilizing the AutoFTA 3.9 software platform, a fault tree model of the beam source system was established. Minimal cut set analysis was performed to identify the system’s weak points. The research employed AutoFTA 3.9 for both qualitative analysis and quantitative calculations, obtaining the failure probabilities of critical components. Furthermore, the F-V importance measure and mean time between failures (MTBF) were applied to analyze the system. This provides a theoretical basis and practical engineering guidance for enhancing the operational reliability of the NNBI system. The evaluation methodology developed in this study can be extended and applied to the reliability analysis of other high-power particle acceleration systems. Full article

Electric buses (EBs) are increasingly adopted for their environmental and operational benefits, yet their real-world efficiency is influenced by climate, route characteristics, and auxiliary energy demands. While most existing research identifies winter as the most energy-intensive season due to cabin heating and reduced battery performance, this study presents a contrasting perspective based on a three-year longitudinal analysis of the LYMMO fleet in Orlando, Florida—a subtropical U.S. region. The findings reveal that summer is the most energy-intensive season, primarily due to sustained HVAC usage driven by high ambient temperatures—a seasonal pattern rarely reported in the current literature and a key regional contribution. Additionally, idling time exceeds driving time across all seasons, with HVAC usage during idling emerging as the dominant contributor to total energy consumption. To mitigate these inefficiencies, a proxy-based HVAC energy estimation method and an optimization model were developed, incorporating ambient temperature and peak passenger load. This approach achieved up to 24% energy savings without compromising thermal comfort. Results validated through non-parametric statistical testing support operational strategies such as idling reduction, HVAC control, and seasonally adaptive scheduling, offering practical pathways to improve EB efficiency in warm-weather transit systems. Full article

This study analyzed the probability of damage in heat transport pipelines buried in urban areas using pipeline attribute information and damage history data and developed an AI-based predictive model. A dataset was constructed by collecting spatial and attribute data of pipelines and defining basic units according to specific standards. Damage trends were analyzed based on pipeline attributes, and correlation analysis was performed to identify influential factors. These factors were applied to three machine learning algorithms: Random Forest, eXtreme gradient boosting (XGBoost), and light gradient boosting machine (LightGBM). The model with optimal performance was selected by comparing evaluation indicators including the F2-score, accuracy, and area under the curve (AUC). The LightGBM model trained on data from pipelines in use for over 20 years showed the best performance (F2-score = 0.804, AUC = 0.837). This model was used to generate a risk map visualizing the probability of pipeline damage. The map can aid in the efficient management of urban heat transport systems by enabling preemptive maintenance in high-risk areas. Incorporating external environmental data and auxiliary facility information in future models could further enhance reliability and support the development of a more effective maintenance decision-making system. Full article

To analyze the wear performance induced by rotor–stator rubbing in an aero-engine sealing structure under authentic operating conditions, a transonic rotor system with double bearing is constructed. This system incorporates the disk, shaft, blades, joint bolts, and auxiliary support structure. The system was evaluated in terms of its critical speed, vibration characteristics, component strength under operational conditions, and response characteristics in abnormal extreme scenarios. A ball screw-type feeding system is employed to achieve precise rotor–stator rubbing during rotation by controlling the coating feed. Additionally, a quartz lamp heating system is used to apply thermal loads to coating specimens, and the appropriate heat insulation and cooling measures are implemented. Furthermore, a high-frequency rubbing force test platform is developed to capture the key characteristics caused by rubbing. The test rig can conduct response tests of the system with rotor–stator rubbing and abrasion tests with tip speeds reaching 425 m/s, feed rates ranging from 2 to 2000 μm/s, and heating temperatures up to 1200 °C. Test debugging has confirmed these specifications and successfully executed rubbing tests, which demonstrate stability throughout the process and provide reliable rubbing force test results. This designed test rig and analysis methodology offers valuable insights for developing high-speed rotating machinery. Full article

Land Surface Temperature (LST) is essential for understanding the interactions between the land surface and the atmosphere. This study presents a comprehensive evaluation of machine learning (ML)-based downscaling algorithms to enhance the spatial resolution of MODIS LST data from 960 m to 30 m, leveraging auxiliary variables including vegetation indices, terrain parameters, and land surface reflectance. By establishing non-linear relationships between LST and predictive variables through eXtreme Gradient Boosting (XGBoost) and Random Forest (RF) algorithms, the proposed framework was rigorously validated using in situ measurements across China’s Heihe River Basin. Comparative analyses demonstrated that integrating multiple vegetation indices (e.g., NDVI, SAVI) with terrain factors yielded superior accuracy compared to factors utilizing land surface reflectance or excessive variable combinations. While slope and aspect parameters marginally improved accuracy in mountainous regions, including them degraded performance in flat terrain. Notably, land surface reflectance proved to be ineffective in snow/ice-covered areas, highlighting the need for specialized treatment in cryospheric environments. This work provides a reference for LST downscaling, with significant implications for environmental monitoring and urban heat island investigations. Full article

Laser cladding, a cutting-edge surface modification technique for metals, offers a novel approach to enhancing the wear and corrosion resistance of substrates due to its rapid heating and cooling capabilities, precise control over coating thickness and dilution rates, and non-contact processing characteristics. However, disparities in the physical properties between the coating material and the substrate, coupled with the improper utilization of process parameters, can lead to coating defects, thereby compromising the quality of the coating. This paper examines the effects of material systems and process parameters on laser cladding composite coatings and shows that cracking is mainly caused by thermal and residual stresses. This article summarizes the methods for crack improvement and prevention in five aspects: the selection of processes in the preparation stage, the application of auxiliary fields in the cladding process, heat treatment technology, the use of auxiliary software, and the search for new processes and new structural materials. Finally, the future development trends of laser cladding technology are presented. Full article

This study explores the impact of using water-Al₂O₃ nanofluids, at different nanoparticle concentrations, in solar thermal collectors for solar cooling applications. Improving the seasonal energy performance of solar cooling systems is a current research priority, and this work investigates whether nanofluids can significantly enhance system efficiency compared to traditional heat transfer fluids. A transient simulation was carried out using a dynamic model developed in TRNSYS (TRANsient SYstem Simulation), evaluating the system performance throughout the cooling season. The results show that in July, under low volumetric flow conditions and with nanoparticle concentrations of 0.6% and 0.3%, the solar fraction reaches a maximum value of 1. Using a nanofluid at 0.6% concentration leads to significantly higher fractional energy savings compared to pure water. Despite increased pumping energy, the overall energy savings—which include the contribution from an auxiliary boiler—exceed 80% when nanofluids are used. This study goes beyond previous work by providing a dynamic, system-level simulation of nanofluid-enhanced solar cooling performance under realistic operating conditions. The findings demonstrate the practical potential of nanofluids as a valid and more energy-efficient alternative in solar thermal applications. Full article

Two novel cyclometalated platinum(II) complexes based on 2-phenylpyridine (ppy) and 2,4-difluorophenylpyridine (dfppy) ligands in combination with a benzoylthiourea (4-(decyloxy)-N-((4-(decyloxy)phenyl)carbamothioyl)benzamide, BTU) functionalized with decyloxy alkyl chains as auxiliary ligands were synthesized and characterized for their mechanochromic and photophysical properties. Structural characterization was achieved through IR and NMR spectroscopy, single-crystal X-ray diffraction, and TD-DFT calculations. Both complexes exhibit significant photoluminescence with quantum yields up to 28.3% in a 1% PMMA film. The transitions in solution-phase spectra were assigned to mixed metal-to-ligand (MLCT) and intraligand (ILCT) charge–transfer characteristics. Temperature-dependent studies and thermal analyses confirm reversible phase transitions without mesomorphic behavior despite the presence of the two long alkyl chains. Both complexes displayed reversible mechanochromic and solvatochromic luminescence, with a change in emission color from green to red-orange emissions upon grinding and solvent treatment or heating at 80 °C. Full article

Aviation has become an essential part of the modern world’s ability to grow personal, market and international connections. To enable continued benefits while reducing emissions, future aircraft will need radical redesign and novel, complementary technologies. Hydrogen aircraft are potentially the means to emissions reduction. As part of the European Union’s (EU’s) Clean Aviation Joint Undertaking (CAJU), it is aimed to have hydrogen aircraft entering into service by 2035. To realise this, it would require the certification of these aircraft in a relatively short timeline, which the CONCERTO project aims to help enable. Given the lack of mature experimental designs and pending certification processes, this endeavour is ambitious. To accelerate this, dedicated preparation for the certification through regulatory analysis should be complete, requiring initial options for technologies and aircraft operations to be defined. The technologies and operations were defined, analysed and weighted in CONCERTO, upon which a Generic Concept was made, outlined in this paper, with Level 1 on the Certification Readiness Level Scale. The aircraft systems which are likely to experience the largest changes; Fuel Storage, Fuel Distribution, Propulsion, Auxiliary Power Unit (APU), Heat Exchange (HEX) System and Sensing and Monitoring for Hydrogen (H2), will be outlined in this paper with respect to their components and integration challenges, and the subsequent changes to operations to enable this. Full article

Waste heat utilization in fuel cell vehicles represents a critical technology for enhancing overall energy utilization efficiency and environmental adaptability, which reduces auxiliary heating consumption, extends driving range, and minimizes thermal management parasitic losses, holding significance for promoting application of fuel cell commercial vehicles. This study investigates a 49-ton fuel cell heavy-duty truck equipped with waste heat recovery capability, conducting vehicle energy flow experiments under multiple ambient temperatures (including 7 °C, $-7$ °C and $-25$ °C extreme cold conditions), varying load conditions, and waste heat recovery mode switching, with focused analysis on the energy consumption and temperature response of the waste heat recover critical components, to evaluate the energy utilization of fuel cell waste heat. Experimental results demonstrate the substantial impact of waste heat recovery function on the proportion of the warm air positive temperature coefficient (PTC) energy consumption on total energy consumption, showing that deactivating waste heat recovery increased the PTC energy consumption obviously. Besides, activating the waste heat recovery function contributes to elevated the stack radiator outlet temperature under low-temperature operating conditions. Full article

This paper presents a procedure for the energy optimization of domestic hot water (DHW) systems in hotels located in tropical climates that use centralized air conditioning systems. The study aims to maximize heat recovery from chillers and reduce the fuel consumption of auxiliary heaters by optimizing operational variables such as water mass flow in the primary and secondary DHW circuits and outlet temperature of the backup system. The optimization is implemented using genetic algorithms (GA), which enable the identification of the most efficient flow configurations under variable thermal demand conditions. The proposed methodology integrates a thermoenergetic model validated with real operational data and considers the dynamic behavior of hotel occupancy and water demand. The results show that the optimized strategy reduces auxiliary heating use by up to 75%, achieving annual energy savings of 8244 kWh, equivalent to 2.3 tons of fuel, and preventing the emission of 10.5 tons of CO₂. This study contributes to the design of sustainable energy systems in the hospitality sector and provides replicable strategies for similar climatic and operational contexts. Full article

The implementation of renewable energy systems (RESs) in the agricultural sector has significant potential to mitigate the negative effects of fossil fuel-based products on the global climate, reduce operational costs, and enhance crop production. However, the intermittent nature of RESs poses a major challenge to realizing these benefits. To address this, thermal energy storage (TES) and hybrid heat pump (HHP) systems are integrated with RESs to balance the mismatch between thermal energy production and demand. In pursuit of clean energy solutions in the agricultural sector, a 3942 m² greenhouse in Yeoju-si, South Korea, is equipped with 231 solar thermal (ST) collectors, 117 photovoltaic thermal (PVT) collectors, four HHPs, two ground-source heat pumps (GSHPs), a 28,500 m³ borehole TES (BTES) unit, a 1040 m³ tank TES (TTES) unit, and three short-term TES units with capacities of 150 m³, 30 m³, and 30 m³. This study evaluates the long-term performance of the integrated hybrid renewable energy and thermal energy storage systems (HRETESSs) in meeting the greenhouse’s heating and cooling demands. Results indicate that the annual system performance efficiencies range from 25.3% to 68.5% for ST collectors and 31.9% to 72.2% for PVT collectors. The coefficient of performance (COP) during the heating season is 3.3 for GSHPs, 2.5 for HHPs using BTES as a source, and 3.6 for HHPs using TTES as a source. During the cooling season, the COP ranges from 5.3 to 5.7 for GSHPs and 1.84 to 2.83 for ASHPs. Notably, the HRETESS supplied 3.4% of its total heating energy directly from solar energy, 89.3% indirectly via heat pump utilization, and 7.3% is provided by auxiliary heating. This study provides valuable insights into the integration of HRETESSs to maximize greenhouse energy efficiency and supports the development of sustainable agricultural energy solutions, contributing to reduced greenhouse gas emissions and operational costs. Full article

Crops in greenhouses located in cold climates are frequently affected by high relative humidity (RH). This study presents the design, testing, and analysis of a dehumidifier based on thermoelectric cooling. Thermoelectric dehumidifiers (TEDs) are capable of dehumidifying greenhouses in cold regions while recovering heat for indoor air heating. The design of a TED is based on the specific characteristics of thermoelectric coolers (TECs). A TED consists of a cabinet, four heat exchangers, a duct fan, a water pump, and auxiliary components. The TED performance was evaluated in a Chinese solar greenhouse (CSG) with a volume of approximately 160 m³. The input voltage of the TECs, fan airflow rate, and cold-side fin area affected the TED performance, with their influence varying in magnitude. The radar chart results show that the optimal operating parameters are as follows: a fan airflow rate of 300 m³/h, a TEC input voltage of 15 V, and a cold-side fin area of 0.15 m². With the TED running for 120 min under the optimal parameters, the RH in the CSG decreased by 25.5%, while the air temperature increased by 3.4 °C. The installation of the TED at the bottom of the CSG improved the growing environment of the crops, particularly in the vertical range between 0.2 m and 1.5 m height inside the greenhouse. These findings provide a valuable reference for applying thermoelectric cooling technology in the greenhouse field. Full article

Film cooling can continuously cover a layer of low-temperature gas film on the surface of hot-end components, thereby achieving the effect of isolating high-temperature gas, and can achieve a temperature drop of 600 K. As an advanced and efficient cooling technique, film cooling plays a crucial role in the process of turbine power and efficiency increase, with the key factor influencing its cooling performance being the configuration and arrangement of the film holes. This paper summarizes the design and arrangement of film hole configurations and discusses the potential directions for enhancing film cooling performance. Through analysis, the optimization of film cooling performance is mainly approached from two aspects: first, optimizing the hole configuration, which includes the study of shaped holes, enhancing the cooling performance of cylindrical holes using auxiliary structures, and forming a “reverse kidney-shaped vortex” structure by using a single combined film hole; second, optimizing the arrangement of the cooling holes on the turbine surface to achieve a more uniform and efficient distribution of the cooling film. Future development trends are primarily reflected in the following aspects: designing new, easily manufacturable, high-efficiency film hole configurations and further expanding their stable operating range is an important development direction. It is essential to validate the reverse heat transfer method, assess its applicable range, and, when experimental conditions exceed the applicable range, use related theories to correct its predictive performance. This is key to overcoming the bottleneck in film cooling prediction. It is critical to develop a film hole arrangement guideline that is suitable for various types of film holes and components with temperature differences at the thermal end, to fill the gap in future film cooling optimization design technologies. This study aims to provide new ideas for the optimal design of the cooling system and further improve the power and efficiency of gas turbines. Full article