Molybdenum disulfide(MoS_(2))has shown significant promise as an economic hydrogen evolution reaction(HER)catalyst for hydrogen generation,but its catalytic performance is still lower than noble metalbased ***,a silve...
详细信息
Molybdenum disulfide(MoS_(2))has shown significant promise as an economic hydrogen evolution reaction(HER)catalyst for hydrogen generation,but its catalytic performance is still lower than noble metalbased ***,a silver nanoparticles(Ag NPs)-decorated 1T/2H phase layered MoS_(2) electrocatalyst grown on titanium dioxide nanorod arrays(Ag NPs/1T(2H)MoS_(2)/TNRs)was prepared through acid-tunable ammonium ion *** advantage of MoS_(2) layered structure and crystal phase controllability,as-prepared Ag NPs/1T(2H)MoS_(2)/TNRs exhibited ultrahigh HER ***-proposed strategy combines facile hydrogen desorption(Ag NPs)with efficient hydrogen adsorption(1T/2H MoS_(2))effectively circumventes the kinetic limitation of hydrogen desorption by 1T/2H MoS_(2).The as-prepared Ag NPs/1T(2H)MoS_(2)/TNRs electrocatalyst exhibited excellent HER activity in 0.5 mol/L H2SO4 with low overpotential(118 mV *** hydrogen electrode(RHE))and small Tafel slope(38.61 mV/dec).The overpotential exhibts no obvious attenuation after 10 h of constant current ***-principles calculation demonstrates that as-prepared 1T/2H MoS_(2) exhibit a large capacity to store *** protons can be subsequently transferred to Ag NPs,which significantly increases the hydrogen coverage on the surface of Ag NPs in HER process and thus change the rate-determining step of HER on Ag NPs from water dissociation to hydrogen *** study provides a unique strategy to improve the catalytic activity and stability for MoS_(2)-based electrocatalyst.
The photochemical system,which utilizes only solar energy and H_(2)O/CO_(2) to produce hydrogen/carbon-based fuels,is considered a promising approach to reduce CO_(2) emissions and achieve the goal of carbon *** date,...
详细信息
The photochemical system,which utilizes only solar energy and H_(2)O/CO_(2) to produce hydrogen/carbon-based fuels,is considered a promising approach to reduce CO_(2) emissions and achieve the goal of carbon *** date,numerous photochemical systems have been developed to obtain a viable solar-to-fuel production system with sufficient energy ***,more effort is still needed to meet the requirements of industrial *** this review,we systematically discuss a typical photochemical system for solar-to-fuel production,from classical theories and fundamental mechanisms to raw material selection,reaction condition optimization,and unit device/system advancement,from the viewpoint of ordered energy ***-of-the-art photochemical systems,including photocatalytic,photovoltaic-electrochemical,photoelectrochemical,solar thermochemical,and other emerging systems,are *** highlight the existing bottlenecks and discuss the developing trend of this ***,optimization strategies and new opportunities are proposed to enhance photochemical systems with higher energy efficiency.
China is the largest producer and consumer of calcium carbide in the *** calcium carbide industry is an indispensable industry to support the basic life of *** huge production capacity of calcium carbide is accompanie...
详细信息
China is the largest producer and consumer of calcium carbide in the *** calcium carbide industry is an indispensable industry to support the basic life of *** huge production capacity of calcium carbide is accompanied by a large number of solid waste carbide *** to the immature treatment technology of carbide slag,a large number of carbide slag are stacked on-site,resulting in land occupation,air-drying,easy take-off ash,and pollution of the environment and water *** China,calcium carbide is mainly used to produce acetylene and further utilized,80%of which is used to produce polyvinyl chloride(PVC).A large amount of carbide slag is not used,while only a small part is used in the traditional building materials industry,flue gas desulfurization,sewage treatment,etc.,however,the economic benefits are ***,converting the solid waste carbide slag produced by the calcium carbide industry into high value-added CaCO3,CaCl2,CaSO4 whiskers,*** become a potential way to expand the development field of the calcium carbide industry and is environmentally *** paper focuses on summarizing the traditional and emerging high value-added utiliza-tion technologies of carbide slag,and then introduces the application research of carbide slag in carbon emission ***,the defects of these technologies are summarized and further research directions are *** study provides basic guidance for the diversified development of efficient resource utilization of carbide *** abstract Diversified development of calcium carbide industry,resource utilization of solid waste carbide slag and its application of carbon emission reduction have been fully reviewed.
Helium-xenon Brayton cycle systems have significant potential as the energy conversion system for small-scale reactors in remote land,deep-sea,and space applications due to a range of advantages,including high cycle e...
详细信息
Helium-xenon Brayton cycle systems have significant potential as the energy conversion system for small-scale reactors in remote land,deep-sea,and space applications due to a range of advantages,including high cycle efficiency,compact system structures,and chemical *** objective of this review is to provide a comprehensive understanding of the helium-xenon Brayton cycle system based on the projects and ***,the basic information and development history are introduced,and a series of typical designs are ***,the system configurations,cycle parameter analysis and optimization are ***,the key components are classified,such as turbine,compressor,and heat ***,the dynamic processes and control strategies are introduced in different ***,the deficiency and prospect of current research are *** review covers the representative helium-xenon Brayton cycle systems,which could provide a reference for promoting the development of energy conversion systems.
As the global climate change and increasing requirement for thermal comfort of human, the thermal demand in the heating period is gradually climbing. The district heating system (DHS) with combined heat and power (CHP...
详细信息
A double reheat ultra-supercritical boiler is an important development direction for high-parameter and large-capacity coal-fired power plants due to its high thermal efficiency and environmental *** has developed a 1...
详细信息
A double reheat ultra-supercritical boiler is an important development direction for high-parameter and large-capacity coal-fired power plants due to its high thermal efficiency and environmental *** has developed a 1000 MW double reheat ultra-supercritical boiler with steam parameters of 35 MPa at 605℃/613℃/613℃.Reasonable water wall design is one of the keys to safe and reliable operation of the *** order to examine the thermal-hydraulic characteristics of the double reheat ultra-supercritical boiler,the water wall system was equivalent to a flow network comprising series-parallel circuits,linking circuits and pressure nodes,and a calculation model was built on account of the conservation equations of energy,momentum and *** the iterative solving of nonlinear equations,the prediction parameters of the water wall at boiler maximum continue rate(BMCR),75%turbine heat-acceptance rate(THA)and 30%THA loads,including total pressure drops,flow distribution,outlet steam temperatures,fluid and metal temperatures were *** results of calculation exhibit excellent thermal-hydraulic characteristics and substantiate the feasibility of the water wall design of the double reheat ultra-supercritical boiler.
In the process of pyrolysis and combustion of coal particles, coal structure evolution will be affected by the ash behavior, which will further affect the char reactivity, especially in the ash melting temperature zon...
详细信息
In the process of pyrolysis and combustion of coal particles, coal structure evolution will be affected by the ash behavior, which will further affect the char reactivity, especially in the ash melting temperature zone. Lu’an bituminous char and ash samples were prepared at the N_(2) and air atmospheres respectively across ash melting temperature. A scanning electron microscope (SEM) was used to observe the morphology of char and ash. The specific surface area (SSA) analyzer and thermogravimetric analyzer were respectively adopted to obtain the pore structure characteristics of the coal chars and combustion parameters. Besides, an X-ray diffractometer (XRD) was applied to investigate the graphitization degree of coal chars prepared at different pyrolysis temperatures. The SEM results indicated that the number density and physical dimension of ash spheres exuded from the char particles both gradually increased with the increasing temperature, thus the coalescence of ash spheres could be observed obviously above 1100℃. Some flocculent materials appeared on the surface of the char particles at 1300℃, and it could be speculated that β-Si_(3)N_(4) was generated in the pyrolysis process under N_(2). The SSA of the chars decreased with the increasing pyrolysis temperature. Inside the char particles, the micropore area and its proportion in the SSA also declined as the pyrolysis temperature increased. Furthermore, the constantly increasing pyrolysis temperature also caused the reactivity of char decrease, which is consistent with the results obtained by XRD. The higher combustion temperature resulted in the lower porosity and more fragments of the ash.
The supercritical water fluidized bed(SCWFB)is a recently introduced reactor for biomass gasification that does not release *** groups of Geldart B-type quartz sands with different particle sizes were fluidized at a s...
详细信息
The supercritical water fluidized bed(SCWFB)is a recently introduced reactor for biomass gasification that does not release *** groups of Geldart B-type quartz sands with different particle sizes were fluidized at a system pressure of 20-27 MPa and system temperature of 410-570℃.A series of experiments were performed for determining the drag coefficient and volume fraction of *** effects of the particles’size,superficial velocity,system pressure,and temperature on the drag coefficient and volume fraction are *** addition,a correlation between experimental and computed values is demonstrated for both the drag coefficient and volume fraction in *** relative error of the correlation is within±30%.The results of this study provide significant guidance for the scaling-up design of SCWFBs and for the development of supercritical water gasification technology.
Although having been increasingly studied, there is still controversy as to when the addition of nanoparticles could improve the drag reduction performance of polymer drag reducer and particularly what is the underlyi...
详细信息
Although having been increasingly studied, there is still controversy as to when the addition of nanoparticles could improve the drag reduction performance of polymer drag reducer and particularly what is the underlying mechanism from the fluid dynamics viewpoint. The drag reduction effects of adding SiO_(2) nanoparticles to various polymer polyacrylamide(PAM) solutions were examined in this *** optimal combination of SiO_(2) nanoparticles with cationic polyacrylamide was ***,the addition of SiO_(2) nanoparticles to cationic polyacrylamide solution was shown to be quite efficient for reducing drag, but only at higher flow rates with Reynolds numbers more than 6000, below which the nanoparticle addition is even negative. The addition of SiO_(2) nanoparticles to the PAM solution is supposed to play a dual role. The first is an increase in flow resistance caused by the Brownian motion of nanoparticles, while the second is a decrease in flow resistance caused by acting as nodes to protect the polymer chain from shear-induced breaking under high shear action. At optimal nanoparticle concentration and under higher Reynolds numbers, the later effect is dominant, which could improve the drag reduction performance of polymer drag reducers. Our work should serve as a guide for the application of natural gas fracturing, where the flow rate is frequently very high.
Liquid Droplet Radiator (LDR) system is regarded as a quite promising waste heat rejection system for aerospace engineering.A comprehensive review on the state-of-the-art of LDR system was carried *** thermal design c...
详细信息
Liquid Droplet Radiator (LDR) system is regarded as a quite promising waste heat rejection system for aerospace engineering.A comprehensive review on the state-of-the-art of LDR system was carried *** thermal design considerations of crucial components such as working fluid,droplet generator and collector,intermediate heat exchanger,circulating pump and return pipe were *** state-of-the-art of existing mathematical models of radiation and evaporation characteristics of droplet layer from literatures were ***,thermal designs of three LDR systems were *** weight and required planform area between the rectangular and triangular LDR systems were respectively compared and the evaporation models for calculating the mass loss were *** on the review,some prospective studies of LDR system were put forward in this paper.
暂无评论