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Pool boiling in porous media has been applied in various thermal management systems by using latent heat and increasing the heat transfer area and thermal conduction path to improve the heat transfer performance. In mechanical equipment, vibration is an inevitable problem due to reasons such as engine operation and high-speed relative motion between transmission system components, which causes the system components to be affected by vibration forces or vibration accelerations. This study focuses on a review of published articles about the effects of mechanical vibration on the characteristics of boiling process in porous media by two aspects: heat transfer performance and bubble dynamics. Heat transfer coefficient (HTC) and critical heat flux are two main parameters used to measure the boiling heat transfer characteristics of porous media. For bubble dynamics investigations, properties such as migration, fragment, coalescence, departure diameter and frequency are the focus of research attention. Different mechanical vibration parameters, i.e., direction, frequency, and amplitude, will have different effects on the above characteristics. It is worth mentioning that the greatest influence occurs under resonance conditions, and this has been verified through experimental and simulation calculations. This review highlights the importance of considering mechanical vibrations in the design and optimization of porous media systems for efficient heat transfer applications. Further research is warranted to explore the detailed mechanisms and optimize the vibration parameters for enhanced heat transfer performance in thermal management systems using porous media.

Fullerene-based materials are widely used as acceptor and electron transport layer materials in organic and planar perovskite solar cells. Modeling of electronic properties such as band alignment and charge transport for these applications is typically done using optimized geometries. Here, we estimate the effects of nuclear motions on band structure, and electron and hole transport in two prototypical fullerenes, C60 and C70. We model the dynamics in solid fullerenes using Density Functional Tight Binding and we use the Density Functional Theory based Projection of Monomer Orbitals on Dimer Orbitals (DIPRO) approach to estimate the effects on the charge transfer integral in the Marcus approximation. We show that room-temperature molecular dynamics cause a shift and spread of frontier orbital energies on the order of 0.1 eV, which leads to an increase by more than a factor of two in the Marcus exponent, and can cause a decrease by up to orders of magnitude in the overlap integral, leading, in most cases, to an overall decrease in the charge transport rate.

The power module package insulation is prone to partial discharge (PD) under fast square pulses, which is one of the main reasons for power module packaging failure. However, there are few studies on PD under square electrothermal coupling stress. One of the important reasons is that the electromagnetic interference and displacement current generated by the rising and falling edges of the square pulse seriously interfere with the detection of PD. To address this problem, this paper proposes a multi-spectral optical detection method with high sensitivity and strong anti-interference. Based on the multi-spectral synchronous detection platform, the high-temperature PD characteristics of power module package insulation under square pulses are studied. The results show that the partial discharge inception voltage (PDIV) decreases with increasing temperature, and the intensity of the PD multi-spectral signal increases with increasing temperature. In addition, the statistical analysis of the maximum optical signal intensity, cumulative optical signal intensity, number of PDs, and phase of PD under square pulse shows that with the increase of temperature, the maximum optical signal intensity and cumulative optical signal intensity of PD increase, and PD events mostly occur on both sides of the square pulse. Among them, the optical signal in the near-ultraviolet band is dominant, and the near-infrared signal has an obvious increase trend. These findings are of great significance for the reliability detection of power module package insulation.

The accelerator-driven sub-critical system is driven by external neutron sources, which are generated by the spallation reaction and maintain the stable operation of the sub-critical core, while the external neutron source increases the complexity of reactor neutron kinetic processes. This article focuses on simulation analysis of neutron space–time kinetics with a dynamic analysis code, which is developed based on the improved quasi-static approximation and Monte Carlo neutron transport method. The amplitude function and shape functions are solved to achieve the dynamics simulation process. Then, the transient responses of beam interruptions and reactivity insertions are calculated and analyzed for an experimental facility. To further verify the correctness and reliability of dynamic behavior, the simulation results are compared with experimental values, and the results show that the normalized neutron fluxes varying with time are in good agreement with the corresponding values. It can be concluded that the improved quasi-static coupled probability theory method can be used to solve the neutron space–time kinetic problem of the experimental facility, and the results are reliable.

Microalgal lipid recovery for biodiesel production is currently considered suboptimal, but pre-treatment of algal biomass, the use of solvent mixtures and the positioning of transesterification can lead to increased yields. Here, the effect of various reportedly successful pre-treatments and solvent mixtures were directly compared to each other and combined with direct and indirect transesterification methods using the oleaginous microalga Tetraselmis sp. M8. Microwave and thermal pre-treatments were applied and the total lipid and fatty acid methyl ester (FAME) recoveries were investigated. The application of pre-treatments increased FAME recovery through indirect transesterification when a Soxhlet system was used but they had no significant effect for direct transesterification. Gravimetric analyses of total lipids revealed that lipid recovery was highest when utilizing the chloroform-based Bligh and Dyer extraction method; however FAME yield was the highest when applying a Soxhlet system utilizing a solvent mixture of hexane-ethanol (3:1). Total lipid recovery did not necessarily correlate with the recovery of FAMEs. The highest FAME recovery was achieved from thermal or microwave pre-treated biomass followed by indirect transesterification through Soxhlet extraction. FAME recovery could be more than doubled (increase of up to 171%) under these conditions. We conclude that a simple thermal pre-treatment (80°C for 10 min) in combination with solvent mixture extraction through indirect transesterification may present a cost-effective and scalable option for large-scale lipid extraction from microalgae.

The insulation performance of oil-immersed paper bushings is prone to deteriorate, primarily due to moisture intrusion and thermal aging. The frequency domain spectroscopy (FDS) method is commonly employed to assess the insulation condition of the bushing. However, identifying and extracting relaxation polarization information from the low-frequency region of the FDS curve can be challenging, and there is little research about the condition evaluation under the combined effects of aging states and moisture content. To address this issue, this article uses the Taylor formula mathematical model to extract characteristic parameters from the dielectric modulus curve of OIP bushings and uses the KNN algorithm to achieve the evaluation of aging and moisture status. Then, the effectiveness and accuracy of the proposed method are validated on three field OIP bushings. The results demonstrate that the evaluation accuracy of the proposed method exceeds 83%, which has significant advantages compared to other classification algorithms. The innovation of this article lies in extracting new feature parameters and combining them with intelligent classification algorithms to evaluate the moisture and aging state of the bushing.

Global demand for both clean energy carriers and agricultural nutrients continues to grow rapidly, alongside increasing quantities of waste globally, interlinked challenges that may be addressed with interlinked solutions. We report on the potential efficiency and Greenhouse Gas (GHG) intensity of several configurations of a new, sustainability-driven ammonia (NH3) production processes to determine whether a waste-based process designed first around carbon dioxide (CO2) capture can compete with other available NH3 technologies. This is assessed via different scenarios: Two hydrogen generating options are paired with four CO2 fates. For either an anaerobic digestion-centered process or a two-stage dark fermentation coupled with anaerobic digestion process, the resultant CO2 may be captured and injected, sold to the marketplace, released directly in the atmosphere, or converted to urea in order to produce a green substitute for synthetic NH3. Modeled yields range from 47 t NH3 when the resultant CO2 is released or captured, or 3.8 t NH3 and 76.5 t urea when the system is designed to produce no unutilized CO2. Among the technologies assessed, NH3 production where CO2 is captured for anaerobic digestion-only is the most efficient for GHG emissions and water consumption, while the two-stage requires less energy on a fertilizer-N basis. GHG emissions for anaerobic digestion-only are approximately 8% lower than the two-stage. The best of the proposed technology configurations consumes about 41% less energy than water electrolysis coupled with Haber-Bosch and approximately 27% lower energy than Steam Methane Reforming (SMR) coupled with Haber-Bosch per kg NH3.

Les systèmes de pompage d'eau à énergie solaire photovoltaïque connaissent un grand succès dans les régions où il n'y a pas de possibilité de connecter le réseau. La technologie photovoltaïque convertit l'énergie solaire en énergie électrique pour faire fonctionner une pompe à eau à moteur CC ou CA. Dans le cas d'une pompe à eau à moteur solaire à courant alternatif, elle engage deux étages de conversion d'énergie (DC-DC et DC-AC) dans l'unité de conditionnement d'énergie. Cela a généralement entraîné une augmentation de la taille, des coûts, de la complexité et une diminution de l'efficacité de l'ensemble du système. En outre, l'étage onduleur à deux niveaux existant (DC-AC) génère des harmoniques plus élevées dans la tension de sortie qui détériore les performances du moteur à courant alternatif. En conséquence, un seul étage de conversion d'énergie avec plus de deux niveaux de tension de sortie pourrait être possible en utilisant des onduleurs multiniveaux qui remplacent facilement l'étage d'inversion à deux niveaux pour obtenir des niveaux plus élevés de tensions de sortie ainsi que pour extraire les meilleurs résultats du moteur. De plus, ils peuvent fonctionner avec une fréquence de commutation réduite qui réduit certainement les pertes de commutation. Pourtant, les niveaux de tension accrus comprennent un nombre plus élevé de commutateurs à semi-conducteurs de puissance, la contrainte de tension cumulative et les pertes de commutation rendent le système plus compliqué. Dans cet article, un onduleur innovant à sept niveaux avec cinq commutateurs avait été utilisé pour étudier la pompe à eau à moteur à induction monophasée 0,5 H. P. Cette topologie garantit des pertes de commutation minimales, réduisant ainsi la taille et les coûts d'installation. Afin de mieux comprendre le fonctionnement et les performances de cette topologie proposée, les résultats de simulation effectués dans l'environnement Matlab / Simulink et la mise en œuvre matérielle sont représentés. Los sistemas de bombeo de agua con energía solar fotovoltaica están teniendo mucho éxito en regiones donde no hay oportunidad de conectar la red. La tecnología fotovoltaica convierte la energía solar en energía eléctrica para operar bombas de agua basadas en motores de CC o CA. En el caso de una bomba de agua de motor de CA solar, se acopla a dos etapas de conversión de energía (CC-CC y CC-CA) en la unidad de acondicionamiento de potencia. Esto generalmente resultó en un aumento del tamaño, costo, complejidad y disminución de la eficiencia de todo el sistema. Además, la etapa existente del inversor de dos niveles (CC-CA) genera armónicos más altos en el voltaje de salida que deteriora el rendimiento del motor de CA. Como consecuencia, una sola etapa de conversión de energía con más de dos niveles de voltaje de salida podría ser posible utilizando inversores multinivel que reemplacen fácilmente la etapa de inversión de dos niveles para obtener niveles más altos de voltajes de salida, así como para extraer los mejores resultados del motor. Además, pueden funcionar con una frecuencia de conmutación reducida que sin duda reduce las pérdidas de conmutación. Aún así, el aumento de los niveles de voltaje comprende un mayor número de interruptores semiconductores de potencia, el estrés de voltaje acumulado y las pérdidas de conmutación están haciendo que el sistema sea más complicado. En este trabajo se ha utilizado un innovador inversor de siete niveles con cinco interruptores para investigar la bomba de agua con motor de inducción monofásico 0,5 H.P. Esta topología garantiza pérdidas de conmutación mínimas, reduciendo el tamaño junto con un menor coste de instalación. Con el fin de proporcionar una mejor comprensión del trabajo y el rendimiento de esta topología propuesta, se representan los resultados de la simulación realizados en el entorno MATLAB / Simulink y la implementación de hardware. Solar photovoltaic powered water pumping systems are becoming very successful in regions where there is no opportunity for connecting the grid. The photovoltaic technology converts solar energy into electrical energy for operating DC or AC motor-based water pump. In the case of a solar AC motor water pump, it engages two energy conversion stages (DC-DC and DC-AC) in the power conditioning unit. This usually resulted in increased size, cost, complexity and decreases efficiency of the entire system. In addition, the existing two-level inverter (DC-AC) stage generates higher harmonics in output voltage that deteriorates AC motor performance. As a consequence, a single energy conversion stage with more than two-level output voltage could be possible by utilizing multilevel inverters which replaces two-level inversion stage easily to get higher levels of output voltages as well for extracting best results from the motor. Moreover, they can able to operate with reduced switching frequency that certainly reduces switching losses. Still, the increased voltage levels comprise a higher number of power semiconductor switches, cumulative voltage stress and switching losses are making the system more complicated. In this paper an innovative seven-level inverter with five switches had been taken to investigate 0.5 H. P single phase induction motor water pump. This topology ensures minimum switching losses, lowering size along with less installation cost. In order to provide better insight into the working and performance of this proposed topology the simulation results performed in the MATLAB / Simulink environment and hardware implementation are depicted. أصبحت أنظمة ضخ المياه بالطاقة الشمسية الكهروضوئية ناجحة للغاية في المناطق التي لا توجد فيها فرصة لتوصيل الشبكة. تعمل التكنولوجيا الكهروضوئية على تحويل الطاقة الشمسية إلى طاقة كهربائية لتشغيل مضخة المياه التي تعمل بالتيار المستمر أو محرك التيار المتردد. في حالة مضخة مياه محرك التيار المتردد الشمسية، فإنها تشرك مرحلتين لتحويل الطاقة (DC - DC و DC - AC) في وحدة تكييف الطاقة. وعادة ما يؤدي ذلك إلى زيادة حجم النظام بأكمله وتكلفته وتعقيده وتقليل كفاءته. بالإضافة إلى ذلك، تولد مرحلة العاكس الحالي ثنائي المستوى (DC - AC) توافقيات أعلى في جهد الخرج مما يؤدي إلى تدهور أداء محرك التيار المتردد. ونتيجة لذلك، يمكن أن تكون مرحلة تحويل الطاقة الواحدة التي تحتوي على أكثر من جهد خرج من مستويين ممكنة من خلال استخدام محولات متعددة المستويات تحل محل مرحلة الانقلاب ذات المستويين بسهولة للحصول على مستويات أعلى من الجهد الناتج وكذلك لاستخراج أفضل النتائج من المحرك. علاوة على ذلك، يمكنهم العمل بتردد تبديل منخفض يقلل بالتأكيد من خسائر التبديل. ومع ذلك، فإن زيادة مستويات الجهد تشمل عددًا أكبر من مفاتيح أشباه الموصلات للطاقة، وإجهاد الجهد التراكمي وفقدان التبديل تجعل النظام أكثر تعقيدًا. في هذه الورقة، تم أخذ عاكس مبتكر من سبعة مستويات مع خمسة مفاتيح لفحص 0.5 مضخة مياه بمحرك تحريضي أحادي الطور. تضمن هذه الطوبولوجيا الحد الأدنى من خسائر التبديل، وخفض الحجم جنبًا إلى جنب مع تكلفة تركيب أقل. من أجل توفير نظرة ثاقبة أفضل على عمل وأداء هذه الطوبولوجيا المقترحة، يتم تصوير نتائج المحاكاة التي تم إجراؤها في بيئة ماتلاب / سيمولينك وتنفيذ الأجهزة.