Progress in Energy and Combustion Science最新文献

In this paper, we provide a comprehensive overview of the state-of-the-art in hybrid PV-T collectors and the wider systems within which they can be implemented, and assess the worldwide energy and carbon mitigation potential of these systems. We cover both experimental and computational studies, identify opportunities for performance enhancement, pathways for collector innovation, and implications of their wider deployment at the solar-generation system level. First, we classify and review the main types of PV-T collectors, including air-based, liquid-based, dual air–water, heat-pipe, building integrated and concentrated PV-T collectors. This is followed by a presentation of performance enhancement opportunities and pathways for collector innovation. Here, we address state-of-the-art design modifications, next-generation PV cell technologies, selective coatings, spectral splitting and nanofluids. Beyond this, we address wider PV-T systems and their applications, comprising a thorough review of solar combined heat and power (S–CHP), solar cooling, solar combined cooling, heat and power (S–CCHP), solar desalination, solar drying and solar for hydrogen production systems. This includes a specific review of potential performance and cost improvements and opportunities at the solar-generation system level in thermal energy storage, control and demand-side management. Subsequently, a set of the most promising PV-T systems is assessed to analyse their carbon mitigation potential and how this technology might fit within pathways for global decarbonization. It is estimated that the REmap baseline emission curve can be reduced by more than 16% in 2030 if the uptake of solar PV-T technologies can be promoted. Finally, the review turns to a critical examination of key challenges for the adoption of PV-T technology and recommendations.

Proton exchange membrane water electrolysis (PEMWE), as a promising technology for hydrogen production from renewable energy sources, has great potential for industrial application. Gas bubbles are known to influence the PEMWE cell performance significantly, but a full picture of bubble behaviors and their impacts on cell performance has been lacking. In this review, we first discuss the most recent advances toward understanding the bubble evolution and transport processes as well as the mechanisms of how bubbles impact the PEMWE. Then the state-of-the-art bubble management methods to mitigate bubble-induced performance losses are summarized. Due to the similarity between PEMWE and anion exchange membrane water electrolysis (AEMWE), we also extend related discussions for AEMWE. Lastly, we present principles of bubble management, followed by an outlook of scientific questions and suggestions for future research priorities.

Is full recyclability of polyolefins via chemical recycling a dream, or can it become a reality? The main problem in recycling plastic waste is that its composition is highly heterogeneous while sorting and purifying solutions to obtain mono-streams are complex and require large investments, thereby hampering the economy of scale. Ideally, novel chemical recycling processes are designed to have mixed plastic wastes as input and higher value products are produced such as C₂–C₄ olefins or aromatics instead of a low value oil. In this review we show the directions how we can realize these objectives. Classical thermal pyrolysis offers some possibilities but requires very high temperatures exceeding 800 °C to transform the plastic waste back into the desired temperatures. Nevertheless, because of its robustness, thermal pyrolysis of polyolefinic plastic waste is currently intensively studied and the first industrial applications are operated at low to medium temperature range to maximize oil as the main product. Catalytic pyrolysis is still under development, but under ideal lab-scale conditions around 85 wt.% of C₂–C₄ olefins can be produced when pure polyolefin feeds are used. With improved catalyst design it should be possible to get this number further up without affecting the catalyst stability. As the yield of light olefins in pyrolysis is impacted by both the process design (reactor type, the efficiency of plastic sorting prior to conversion, flexibility towards feed composition) and experimental parameters (temperature, catalyst type, catalyst/feed ratio, contact mode, residence time, addition of inert or reactants) also further improvements are possible in this respect. To industrialize pyrolysis of plastic waste, short residence times (<1 s) are crucial to avoid secondary reactions and by-products such as methane, coke, and aromatics. Pyrolysis reactors that are designed according to these principles, such as downers, spouted fluidized bed, and vortex reactors, are envisaged to result in optimal yields of C₂–C₄ olefins. However, coke formation seems to be inevitable and the reactor designs need to be sufficiently robust to allow for in-situ coke removal. For future research it will be crucial for the industrial viability of plastic waste pyrolysis to improve the purification of the plastic waste stream, optimize both the catalysts selectivity and stability, and design a suitable industrial reactor. It is envisaged that further innovations in these three areas will eventually allow reaching the 90 wt.% target.

Modulating anionic oxygen in metal oxides offers exceptional opportunities for energy material synthesis via redox looping; however, several challenges such as overoxidation and catalyst deactivation need to be solved. This paper provides an overview of the state-of-the-art schemes for the selective synthesis of valuable chemicals via lattice oxygen-induced redox looping. Compared with previously published works, this review focuses on lattice oxygen modulated energy transformation technologies via chemical looping. This review discusses the chemical looping-based selective oxidation of methane to syngas/methanol, the oxidative coupling of methane, oxidative steam reforming of alcohols, and the oxidative dehydrogenation of hydrocarbons in the lattice oxygen-induced selective oxidation section. Additionally, moderate- and low-temperature Ellingham diagrams are extended to deduce the reactivity of the lattice oxygen based on thermodynamic calculation, which helps for oxygen carrier selection and product modulation. Moreover, less-researched but potential approaches to produce value-added energy materials by lattice oxygen are proposed in the perspective section, including selective oxidation of glycerol to glyceric acid, selective oxidation of methanol to acetic acid, and oxidative methane aromatization. Finally, implications for advanced oxygen carrier material design, preparation, and characterization are also overviewed. This study expands the scope of the lattice oxygen regulated energy conversion, which seeks to benefit both fundamental research and industrial applications of value-added energy material generation via lattice oxygen modulated energy transformation.

Aromatic hydrocarbons are important components of petroleum-based transportation fuels, biomass, coal, and solid waste, etc. The reaction kinetics of aromatic hydrocarbons largely determine the combustion characteristics and pollutant emission of vehicle/jet engines, power plants, and industrial reactors. While a few reviews have recently focused on aromatic hydrocarbons in gasoline surrogate fuels, thermochemical conversion of biomass/coal/solid waste, and combustion soot formation, a dedicated overview of research on the combustion chemistry of aromatic hydrocarbons is still lacking. In the last decades, valuable investigations addressing the reaction kinetics were reported based on the measurements from pyrolysis, oxidation, flames, shock tubes, and rapid compression machines, complemented by quantum chemistry and detailed kinetic modeling. Significant advances have allowed a better understanding of such physicochemical reacting system, from aromatic decomposition, oxidation, to pollutants formation. In the present review, aromatic hydrocarbons are systematically categorized to five common classes: basic, mono-substituted, multi-substituted, hydrogenated, and polycyclic aromatics. Fundamental aromatic combustion chemistry consists of the reactions of basic aromatic molecular structures. Then the aryl group strongly influences the reaction kinetics of aromatic derivates, which leads to very different combustion performance from those ordinary paraffins, olefins, and naphthenes. This paper seeks to provide an introduction to the knowledge gathered in the recent research, highlight pertinent aspects of this rapidly enriching information, and outlook the challenges towards fundamentally comprehensive aromatic combustion chemistry and practically efficient aromatic combustion model.

The emergence of single atom sites as a frontier research area in catalysis has sparked extensive academic and industrial interest, especially for energy, environmental and chemicals production processes. Single atom catalysts (SACs) have shown remarkable performance in a variety of catalytic reactions, demonstrating high selectivity to the products of interest, long lifespan, high stability and more importantly high atomic metal utilization efficiency. In this review, we unveil in depth insights on development and achievements of SACs, including (a) Chronological progress on SACs development, (b) Recent advances in SACs synthesis, (c) Spatial and temporal SACs characterization techniques, (d) Application of SACs in different energy and chemical production, (e) Environmental and economic aspects of SACs, and (f) Current challenges, promising ideas and future prospects for SACs. On a whole, this review serves to enlighten scientists and engineers in developing fundamental catalytic understanding that can be applied into the future, both for academia or valorizing chemical processes.

Climate neutrality is becoming a core long-term competitiveness asset within the aviation industry, as demonstrated by the several innovations and targets set within that sector, prior to and especially after the COVID-19 crisis. Ambitious timelines are set, involving important investment decisions to be taken in a 5-years horizon time. Here, we provide an in-depth review of alternative technologies for sustainable aviation revealed to date, which we classified into four main categories, namely i) biofuels, ii) electrofuels, iii) electric (battery-based), and iv) hydrogen aviation. Nine biofuel and nine electrofuel pathways were reviewed, for which we supply the detailed process flow picturing all input, output, and co-products generated. The market uptake and use of these co-products was also investigated, along with the overall international regulations and targets for future aviation. As most of the inventoried pathways require hydrogen, we further reviewed six existing and emerging carbon-free hydrogen production technologies. Our review also details the five key battery technologies available (lithium-ion, advanced lithium-ion, solid-state battery, lithium-sulfur, lithium-air) for aviation. A semi-quantitative ranking covering environmental-, economic-, and technological performance indicators has been established to guide the selection of promising routes. The possible configuration schemes for electric propulsion systems are documented and classified as: i) battery-based, ii) fuel cell-based and iii) turboelectric configurations. Our review studied these four categories of sustainable aviation systems as modular technologies, yet these still have to be used in a hybridized fashion with conventional fossil-based kerosene. This is among others due to an aromatics content below the standardized requirements for biofuels and electrofuels, to a too low energy storage capacity in the case of batteries, or a sub-optimal gas turbine engine in the case of cryogenic hydrogen. Yet, we found that the latter was the only available option, based on the current and emerging technologies reviewed, for long-range aviation completely decoupled of fossil-based hydrocarbon fuels. The various challenges and opportunities associated with all these technologies are summarized in this study.

Internal combustion in transport vehicles is still one of the biggest contributors to ultrafine particle emissions which have been proven to have many adverse effects on human health and the environment in general. To mitigate this problem a variety of particle filters have been developed and along with these filters a whole range of models aiming to optimise filter performance. This paper reviews a wide variety of particulate filter models for vehicular emission control and presents the volume of work in a unified and consistent notation. Particle filtration models are examined with respect to their filtration efficiency, the way they handle particle deposits within the filter wall, the formation of filter cake and the role of catalytic conversion and the effect of gaseous emission. Further, the impact of the chemical and physical properties of particulate deposits on the filter regeneration process is analysed and reaction pathways and rates are presented. In addition the accumulation of ash deposits and its impact on the filter behaviour is critically reviewed. Finally, various measures are identified that can potentially improve the current particle filter models.

Microalgae have gained considerable attention as an alternative feedstock for the biofuel production, particularly in combination with genetic modification strategies that target enhanced lipid productivity. To tackle climate change issues, phasing out the usage of fossil fuels is seen as a priority, where the utilization of biofuel from microalgae serves as a potential sustainable energy source for various applications. These photosynthetic microalgae utilize solar energy and carbon dioxide to produce energy-rich compounds (i.e., starch and lipids), that can be further converted into biofuels of different types. Among different types of biofuels, biodiesel from the transesterification of triacylglycerols stands out as the most sustainable replacement of transportation fuel over fossil-based petroleum diesel. However, hurdles such as limited productivity, overall production cost and challenges in upscaling the algal technology leaves a huge gap on the road to commercialized microalgae-based biofuel. This review article first presents a comprehensive overview of imperative knowledge regarding microalgae in terms of algal classification, factors affecting the growth of microalgae during cultivation and different steps in upstream processing. This review also discusses recent advances in downstream processing of microalgal biorefinery. Additionally, this review paper focuses on deliberating various recent strategies of genetic modifications and their feasibility for enhanced lipid productivity in microalgae. Finally, the current challenges and future perspectives of microalgae-based biofuels are highlighted in this review discussing several aspects, including sustainability of microalgae-based biofuel production, current status of algae-based industry, risks and legislation considerations of genetic modification of microalgae.