Cu/CHA and sodium-promoted Cu/CHA catalysts were prepared and applied to catalyze NH3-SCR reaction. Also, the effect of phosphorus poisoning on the catalytic performance of these two catalysts were ...explored. Compared with Cu/CHA catalyst, sodium-promoted Cu/CHA catalyst presented better catalytic performance, which was attributed to the optimized distribution of copper active sites. Moreover, it was proved that sodium ions as sacrificial sites could effectively protect copper active ions and improve the phosphorus poisoning resistance of the sodium-promoted Cu/CHA catalyst.
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•CuCHA and sodium-promoted Cu/CHA catalysts were synthesized.•Sodium-promoted Cu/CHA catalyst presented better catalytic performance.•The phosphorus poisoning resistance of sodium-promoted Cu/CHA catalyst was improved.•Sodium ions acted as sacrificial sites to protect copper active sites.
As zero‐emission technologies, a daytime radiative cooling (RC) strategy developed recently, and photovoltaic (PV) and thermoelectric (TE) technologies have aroused great interest to reduce fossil ...fuel consumption and carbon emissions. How to integrate these state‐of‐the‐art technologies to maximise clean electricity from the sun and space remains a huge challenge, and the limit efficiency is still unclear. In this study, a spectral‐splitting PV‐TE hybrid system integrated with RC is proposed to maximise clean electricity from the sun and space without any emissions. For the sun acting as a typical constant heat‐flux heat source, the current thermoelectric theory overestimates the thermoelectric efficiency highly since the theory is based on constant temperature‐difference conditions. A new theory based on heat‐flux conditions is employed to achieve maximum thermoelectric efficiency. The PV‐TE hybrid system with RC is superior to the conventional hybrid system, not only in terms of higher efficiency but also in its 24‐h operation capacity. In a system with a single‐junction cell, the total efficiency with 30 suns (39.4%) is higher than the theoretical PV efficiency at 500 suns (38.2%). In a hybrid system with four‐junction cells, total efficiency is over 65% which is superior to most current photoelectric and thermal power systems.
A concentrated spectral‐splitting photovoltaic‐thermoelectric hybrid system integrated with radiative cooling is proposed to maximize clean electricity from the sun and space without any emissions. The system with a low concentration ratio (Cr) can achieve conventional solar cells’ efficiency with a high Cr, and achieve 24‐h operation with maximum efficiency exceeding 65%, which outperforms most current photoelectric and thermal power systems.
The γ-Al2O3 support (nanosphere and nanoflake) was used to support Ag nanoparticles and applied in C3H8-SCR to remove NOx. Ag/Al2O3-flake exhibited superior catalytic activity than Ag/Al2O3-sphere in ...C3H8-SCR. It is found that Al2O3-flake rich in Al octacoordinated ions promoted more Agnδ+ species to disperse on Ag/Al2O3-flake than Ag/Al2O3-sphere. Agnδ+ species could strengthen the low-temperature catalytic activity for HC-SCR while Ag metal particles were unbeneficial since they could promote complete oxidation of hydrocarbon. This was the first time to explore the remarkable effect of Al2O3 intrinsic properties on catalytic activity of alumina-supported catalyst for HC-SCR from the perspective of uniform morphology.
The number of transport vehicles has increased dramatically during the past decades due to global economic growth. The accompanying concern is the huge consumption of fossil fuels, for example, gasoline and diesel, which speeds up global warming. Internal combustion engines produce toxic emissions, where NOx forms nitric acid in the atmosphere, reacts with HCs to form which causes acidification of land and lakes. Currently, it is urgent to develop a leading deNOx technique for the after-treatment of commercial engine-powered vehicles to meet stringent emission legislations.
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•Al2O3-sphere and Al2O3-flake were prepared to support Ag nanoparticles and applied in C3H8-SCR.•Al2O3-flake exhibited excellent catalytic activity for C3H8-SCR.•Al2O3-flake rich in Al octacoordinated ions promoted more Agnδ+ species.•The stability of Ag particles was highly improved when supported on Al2O3-flake.
•Segmental design method is applicable for the S-CO2 recuperator.•Local heat capacity rate ratio has crucial effects in local thermal performance.•The inflection point often appears when local heat ...capacity rate ratio is about one.•Local entransy dissipation number has relatively coherent performance behavior.
The segmental design method is employed to accurately capture the drastic variations of properties in the supercritical carbon dioxide (S-CO2) recuperator. The local heat capacity flow rates of both fluids have drastic changes in sub-heat exchangers even the mass flow rates of both fluids remain unchanged. When the heat duty is given, the local heat conductance, local temperature difference, local effectiveness and local entransy dissipation number have extremums, which appear in the vicinity of the heat capacity rate ratio is one. The heat transfer performance of recuperator improves at the expense of heat conductance. When the total heat conductance is fixed, there exist the maximum local heat flux rates, and the local effectiveness tends to be constant after the local heat capacity rate ratio reaches one, the local entransy dissipation number has the relatively coherent performance behavior in the sub-heat exchangers. The local heat capacity rate ratio has crucial influences on the heat transfer performance of recuperator, and the design parameters must be considered carefully in the design of S-CO2 recuperator.
In the present work, a new shell-and-tube heat exchanger optimization design approach is developed, wherein the dimensionless entropy generation rate obtained by scaling the entropy generation on the ...ratio of the heat transfer rate to the inlet temperature of cold fluid is employed as the objective function, some geometrical parameters of the shell-and-tube heat exchanger are taken as the design variables and the genetic algorithm is applied to solve the associated optimization problem. It is shown that for the case that the heat duty is given, not only can the optimization design increase the heat exchanger effectiveness significantly, but also decrease the pumping power dramatically. In the case that the heat transfer area is fixed, the benefit from the increase of the heat exchanger effectiveness is much more than the increasing cost of the pumping power.
In the present work the field synergy principle is applied to the optimization design of the shell-and-tube heat exchanger with segmental baffles. The field synergy number which is defined as the ...indicator of the synergy between the velocity field and the heat flow is taken as the objective function. The genetic algorithm is employed to solve the heat exchanger optimization problems with multiple design variables. The field synergy number maximization approach for heat exchanger optimization design is thus formulated. In comparison with the initial design, the optimal design leads to a significant cost cut on the one hand and an improvement of the heat exchanger performance on the other hand. The comparison with the traditional heat exchanger optimization design approach with the total cost as the objective function shows that the field synergy number maximization approach is more advantageous.
In the present work, a multi-parameter optimization approach of Isopropanol–Acetone–Hydrogen (IAH) chemical heat pump is developed based on the entransy theory. In the optimization process, the total ...low-temperature heat consumed by the heat pump system generally decreases while the high-temperature heat recovered by the heat pump increases remarkably. When the temperatures of the reboiler and endothermic reaction are fixed, the temperature of exothermic reaction in the optimal design scheme is larger than that in the initial design scheme, and the high-temperature heat released from the exothermic reactor increases significantly in the optimal design scheme. The enthalpy efficiency (COP) and exergy efficiency monotonously increase as the entransy efficiency increases in the optimization process. The entransy efficiency has a definite physical meaning and pays more attention to the quality of the high-temperature heat recovered by the heat pump than enthalpy efficiency; it does not introduce an additional parameter and has more succinct expression than exergy efficiency. The multi-parameter optimization approach taking entransy efficiency as the objective function is very effective in the optimization design of IAH chemical heat pump.
► A multi-parameter optimization approach of chemical heat pump is developed. ► The multi-parameter optimization approach is very effective in first and second law. ► Entransy efficiency is defined based on the entransy theory. ► Entransy efficiency is superior to enthalpy efficiency in quality. ► Entransy efficiency has more succinct expression than exergy efficiency.
Two phosphate- and potassium-solubilizing strains (KNP413 and KNP414) were isolated from the soil of Tianmu Mountain, Zhejiang Province (China) and they were phenotypically and phylogenetically ...characterized. Both isolates effectively dissolved mineral phosphate and potassium, while strain KNP414 showed higher dissolution capacity even than Bacillus mucilaginosus AS1.153, the inoculant of potassium fertilizer widely used in China. When grown on Aleksandrov medium, both strains were rod-shaped spore-formers with a large capsule, and they formed slimy and translucent colonies. The DNA G+C contents were 57.7 mol% for strain KNP413 and 56.1 mol% for strain KNP414. Strain KNP413 shared a 16S rRNA gene sequence similarity of more than 99.1% with strain KNP414 and Bacillus mucilaginosus strains HSCC 1605 and YNUC0001, and a 94.6% similarity with Bacillus mucilaginosus VKM B-1480D, the type strain of Bacillus mucilaginosus. Strains KNP413 and KNP414 together with other Bacillus mucilaginosus were clustered with Paenibacillus strains in a group. The use of a specific PCR primer PAEN515F designed for differentiating the genus Paenibacillus from other members of the Bacillaceae showed that strains KNP413 and KNP414 had the same amplified 16S rRNA gene fragment (0.9-kb) as members of the genus Paenibacillus. In conclusion, phosphate- and potassium-solubilizing strains KNP413 and KNP414 should be integrated into the same species different from strain VKM B-1480D and they might be transferred to the genus of Paenibacillus, i.e. Paenibacillus mucilaginosus.PUBLICATION ABSTRACT
In order to meet the performance requirements of global optimality and path smoothness in robot path planning, a new fusion algorithm of jump-A * algorithm and dynamic window approach is proposed. ...First, A * algorithm is optimized by using the jump point search method and a new distance evaluation function defined by Manhattan and Euclidean distance to obtain global path information. Then take the dynamic window approach as the core by integrating the global path information to safely plan a global optimal path with high smoothness. The experimental results show that the new fusion algorithm proposed in this paper can not only effectively solve the problem of non-continuous curvature and excessive turning angle at the turning points of the path planned by jump-A * algorithm, but also improve the smoothness of the path and the global optimality. This research is beneficial to the motion control of robots and has certain reference for robot navigation.
Based on the entransy dissipation theory, the multi-parameter optimization design of recuperator is conducted in an Isopropanol–Acetone–Hydrogen (IAH) chemical heat pump system. The performance of ...the heat pump system can be improved significantly through the multi-parameter optimization, when the main operation parameters of chemical heat pump remain unchanged. When the main operation parameters of chemical heat pump and the heat transfer area of recuperator remain unchanged, the heat transfer rate of recuperator, the high-temperature heat released from the exothermic reactor, and the coefficient of performance (COP) and exergy efficiency of IAH heat pump system greatly increase while the compressor power decreases remarkably as entransy dissipation number decreases. This is done only by optimizing the combination of design parameters of recuperator taking entransy dissipation number as the objective function under certain constraint conditions, and the cost is no more than the low-temperature waste heat having no practical value.
► Optimization of heat exchanger based on entransy dissipation is conducted at system level. ► The optimization approach is very effective at both component and system levels. ► The performance of the system is improved significantly after the optimization design. ► The obtained high-temperature heat is improved greatly at the expense of low-temperature heat.
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