Progress in Energy and Combustion Science最新文献

The investigation of shock compression in highly exothermic inorganic powder mixtures leading to reaction has been a subject of interest for several decades. In particular, understanding the processes occurring within the time scale of the high-pressure shock state, resulting in the formation of new materials and phases, has garnered significant attention. Chemical reactions in shock-compressed media are generally categorized based on their time scale: i) shock-induced chemical reactions occur in the shock front or shortly behind it (in the stress pulse) during the time scale of mechanical equilibration (<1 μs), and ii) shock-assisted chemical reactions occur on the longer time scale of bulk temperature equilibration (>10 μs) after the state of stress has been released. It is worth noting that a solid-state detonation wave involves a type of combustion with a supersonic exothermic front that accelerates through a medium, ultimately supporting the leading shock front. While extensive discussions have focused on shock-induced and shock-assisted reactions, as well as the solid-state detonation, certain questions regarding the possibility of i) shock-induced reactions occurring within the time scale of high-pressure shock state, and ii) chemical reactions occurring promptly enough after the shock wave to sustain a detonation wave (ultra-fast gasless reactions), remained unanswered. In this paper, we provide a brief review of shock compression of reactive heterogeneous media, with a particular emphasis on recent experimental studies. We critically address the chemical reactions occurring within these material systems and the underlying mechanisms, supported by in-situ and ex-situ experimental evidences. Specifically, our primary focus lies on the aluminum-nickel and the metal nitride-boron systems. Based on our analysis, we conclude that the shock-induced reactions can occur in the time scale of the propagated shock wave and can be explained by the mechanically induced thermal explosion phenomena. However, the observed phenomena so far cannot be attributed to solid-state detonation, since they cannot result in a self-sustained mode of shock wave propagation.

Thermal energy storage (TES) is increasingly important due to the demand-supply challenge caused by the intermittency of renewable energy and waste heat dissipation to the environment. This paper discusses the fundamentals and novel applications of TES materials and identifies appropriate TES materials for particular applications. The selection and ranking of suitable materials are discussed through multi-criteria decision making (MCDM) techniques considering chemical, technical, economic and thermal performance. The recent advancements in TES materials, including their development, performance and applications are discussed in detail. Such materials show enhanced thermal conductivity, reduced supercooling, and the advantage of having multiple phase change temperatures (cascade PCMs). Nano-enhanced PCMs have found the thermal conductivity enhancement of up to 32% but the latent heat is also reduced by up to 32%. MXene is a recently developed 2D nanomaterial with enhanced electrochemical properties showing thermal conductivity and efficiency up to 16% and 94% respectively. Shape-stabilized PCMs are able to enhance the heat transfer rate several times (3–10 times) and are found to be best suited for solar collector and PV-based heat recovery systems. Cascade and molten slats PCMs find their best applications in the thermal management of buildings and the power sector (concentrated solar plants). Microencapsulated, nanoPCMs and shape-stabilized PCMs effectively reduce the supercooling of hydrated salts. The recent trends of TES materials in various applications, including building, industrial, power, food storage, smart textiles, thermal management, and desalination are also briefly discussed. Finally, future research in advanced energy storage materials is also addressed in this study, which is intended to help create new insights that will revolutionize the thermal management field.

Transportation electrification is a promising solution to meet the ever-rising energy demand and realize sustainable development. Lithium-ion batteries, being the most predominant energy storage devices, directly affect the safety, comfort, driving range, and reliability of many electric mobilities. Nevertheless, thermal-related issues of batteries such as potential thermal runaway, performance degradation at low temperatures, and accelerated aging still hinder the wider adoption of electric mobilities. To ensure safe, efficient, and reliable operations of lithium-ion batteries, monitoring their thermal states is critical to safety protection, performance optimization, as well as prognostics, and health management. Given insufficient onboard temperature sensors and their inability to measure battery internal temperature, accurate and timely temperature estimation is of particular importance to thermal state monitoring. Toward this end, this paper provides a comprehensive review of temperature estimation techniques in battery systems regarding their mechanism, framework, and representative studies. The potential metrics used to characterize battery thermal states are discussed in detail at first considering the spatiotemporal attributes of battery temperature, and the strengths and weaknesses of applying such metrics in battery management are also analyzed. Afterward, various temperature estimation methods, including impedance/resistance-based, thermal model-based, and data-driven estimations, are elucidated, analyzed, and compared in terms of their strengths, limitations, and potential improvements. Finally, the key challenges to battery thermal state monitoring in real applications are identified, and future opportunities for removing these barriers are presented and discussed.

Polymer electrolyte fuel cells, including acidic proton exchange membrane fuel cells (PEMFCs) and alkaline anion exchange membrane fuel cells (AEMFCs), are the types of the most promising high-efficiency techniques for conversion hydrogen energy to electricity energy. However, the catalysts’ insufficient activity and stability toward oxygen reduction reaction (ORR) at the cathodes of these devices are still the important constraints to their performance. So far, carbon black supported platinum (Pt/C) and its alloys are still the most practical and best-performing type of catalysts. However, the scarcity of Pt is highly challenging and the high price of commercial catalyst will continue to drive up the cost of both PEMFCs and AEMFCs. Moreover, the traditional carbon black support is susceptible to corrosion especially under electrochemical operation, itself inactive for ORR and weakly binding with Pt-based nanoparticles. In this review, the advanced carbons synthesized by various template methods, including hard-template, soft-template, self-template and combined-template, are systematically evaluated as low-Pt catalyst supports and non-noble catalysts. For the templates-induced carbon-based catalysts, this review presents a comprehensive overview on the carbon supported low-Pt catalysts from aspect of composition, size and shape control as well as the non-noble carbon catalysts such as transition metal-nitrogen-carbons, metal-free carbons and defective carbons. Furthermore, this review also summarizes the applications of low/non-Pt carbon-based catalysts base on the template-induce advanced carbons at the cathodes of PEMFCs and AEMFCs. Overall, the templates-induced carbons can show some perfect attributes including ordered morphology, reasonable pore structure, high conductivity and surface area, good corrosion resistance and mechanical property, as well as strong metal–support interaction. All of these features are of particular importance for the construction of high-performance carbon-based ORR catalysts. However, some drawbacks mainly involve the removal of templates, maintenance of morphological structure, and demetalation. To address these issues, this review also summarizes some effective strategies, such as employing the easily removed hard/soft-templates, developing the advantageous self-templates, enhancing the metal–support interaction by formation of chemical binds, etc. In conclusion, this review provides an effective guide for the construction of template-induced advanced carbons and carbon-based low/non-Pt catalysts with analysis of technical challenges in the development of ORR electrocatalysts for both PEMFCs and AEMFCs, and also proposes several future research directions for overcoming the challenges towards practical applications.

Hydrogen is a promising future energy carrier due to its potential for production from renewable resources. It can be used in existing compression ignition diesel engines in a dual-fuel mode with little modification. Hydrogen's unique physiochemical properties, such as higher calorific value, flame speed, and diffusivity in air, can effectively improve the performance and combustion characteristics of diesel engines. As a carbon-free fuel, hydrogen can also mitigate harmful emissions from diesel engines, including carbon monoxide, unburned hydrocarbons, particulate matter, soot, and smoke. However, hydrogen-fueled diesel engines suffer from knocking combustion and higher nitrogen oxide emissions. This paper comprehensively reviews the effects of hydrogen or hydrogen-containing gaseous fuels (i.e., syngas and hydroxy gas) on the behavior of dual-fuel diesel engines. The opportunities and limitations of using hydrogen in diesel engines are discussed thoroughly. It is not possible for hydrogen to improve all the performance indicators and exhaust emissions of diesel engines simultaneously. However, reformulating pilot fuel by additives, blending hydrogen with other gaseous fuels, adjusting engine parameters, optimizing operating conditions, modifying engine structure, using hydroxy gas, and employing exhaust gas catalysts could pave the way for realizing safe, efficient, and economical hydrogen-fueled diesel engines. Future work should focus on preventing knocking combustion and nitrogen oxide emissions in hydrogen-fueled diesel engines by adjusting the hydrogen inclusion rate in real time.

Polyaromatic hydrocarbons, polycyclic aromatics or polyarenes are a major (by-)product fraction of multiple classical, waste, and bio-refinery operations. They have an extremely negative environmental impact, a minimal market, and a lowering demand. Parallelly, lowly alkylated single ring arenes or monoaromatics (benzene, toluene, and xylenes, the so-called BTX fraction) are highly demanded due to their applications as chemicals or fuels. Herein, we review the status of applied polyaromatic selective ring-opening (SRO) by hydrocracking into monoaromatics. This review addresses the involved mechanisms, applicable catalysts, and reported modeling approaches for SRO. Applying the multivariate analysis to the results reported in the literature using model molecules, we showcase the limitations for extrapolating the obtained knowledge to realistic polyaromatic stream processing. We also provide a statistical evaluation of the suitability of several polyaromatic streams for their SRO processing and assess the markets, usage, and production routes for monocyclic aromatics. Finally, the technologies of these processes are also evaluated and compared, while the most promising one is discussed further based on process simulations and a techno-economic assessment.