As important parts of underground water conveyance equipment, diving tubular pumps are widely used in various fields related to the national economy. Research and development of submersible pumps ...with better performance have become green goals that need to be achieved urgently in low-carbon development. This paper provides an effective approach for the enhancement of the performance of a diving tubular pump by adopting computational fluid dynamics, one-dimensional theory, and response surface methodology. First, the flow loss characteristics of the pump under several flow rate conditions are analyzed by entropy production theory, and then the impeller and guide vanes are redesigned using the traditional one-dimensional theory. Then, the surface response experimental method is used to improve pump hydraulic efficiency. The streamline angle (A) of the front cover of the impeller blade, the placement angle (B) of the middle streamline inlet, and the placement angle (C) of the rear cover flowline inlet are the response variables to optimize the design parameters of the diving tubular pump. Results show that wall entropy production and turbulent kinetic energy entropy production play the leading role in the internal flow loss of the diving tubular pump, while viscous entropy production can be ignored. The flow loss inside the impeller is mainly concentrated at the inlet and the outlet of the impeller blade, and the flow loss inside the guide vane is mainly concentrated in the area near the guide vane and the entrance of the guide vane. A, B, and C are all significant factors that affect efficiency. The order of the influencing factors from strong to weak is as follows: A2 (p = 0.000) > C (p = 0.007) = A × B (p = 0.007) > B (p = 0.023) > B2 (p = 0.066) > A × C (p = 0.094) > A (p = 0.162) > C2 (p = 0.386) > A × B (p = 0.421). The best combination of response variables after surface response test design is A = 9°, B = 31°, and C = 36°. After optimization, the pump efficiency and the head of the model pump are increased by 32.99% and 18.71%, respectively, under the design flow rate. The optimized model pump is subjected to tests, and the test data and the simulation data are in good agreement, which proves the feasibility of using the surface response method to optimize the design of the model pump.
Results on overall pump head and efficiency performance, pressure pulsation and high speed camera visualization of flow patterns behavior are presented for different inlet air-water void fractions at ...a given rotational speed. With the increase of inlet void fractions and decrease of the flow rates, the size of bubbles increase and tend to agglomerate in specific impeller passage locations along the blade chord. The starting point of pump breakdown is related to a strong inward reverse flow occurring in a specific location near the shroud gap of the impeller and volute tongue region. Using a constant air void fraction value of 2%, pressure pulsation frequency results are analyzed in relation with local flow mixture patterns and flow rate modification.
Large quantities of dilute spent sulfuric acid are released in many chemical processes. Recovering the dilute acid is not only profitable to the manufacturer but also imperative to environmental ...protection. This paper proposes a spray evaporator with a Venturi-type nozzle to concentrate the dilute sulfuric acid. Both hot air and dilute acid flow concurrently upwards through the nozzle. Water involved in the droplets is vaporized in the chamber and the dilute acid is concentrated. The bench-scale experimental results show that the dilute acid with initial concentration 18
wt% can be easily concentrated to 40–75
wt%. The measured parameters, such as concentration of outlet sulfuric acid, outlet air temperature and total pressure drop, are in accordance with those estimated from a mathematical model incorporating momentum, mass and heat transfer between the acid and air. The model is also applied to simulate the performance of the concentrator, including variations of droplet diameter, droplet velocity, droplet temperature, air temperature, air absolute humidity as well as pressure drop along the concentrator.
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•Jet fuel can be produced from the dehydration-oligomerization of higher alcohols from ethanol upgrading.•The hierarchical plate like P40(0.2) catalyst has good diffusion and carbon ...resistance.•There was a good linear relationship between external Brønsted acidic and selectivity of C8-C16.•The optimized selectivity of C8-C16 products can reach 66.4 %.
One-pot dehydration-oligomerization of biomass-derived alcohols provides a promising strategy for the production of renewable jet fuels, but it is still a great challenge. In this study, the hierarchically porous plate-like HZSM-5 catalysts were constructed to catalyze dehydration-oligomerization of higher alcohols derived from upgrading of fermentation ethanol. It was observed that the P40(0.2) catalyst showed the best performance with the C8-C16 products selectivity of 66.4%. Systematic investigations revealed that the outstanding performance of P40(0.2) originated mainly from the synergistic effect of the finely tuned acidity and the hierarchical porous plate-like structure. Notably, the good activity of P40(0.2) on dehydration-oligomerization of the actual oil phase from ethanol upgrading confirmed the great potential of practical applications for the synthesis of jet fuels from biomass-derived alcohols.
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•The high content of graphited N-doped carbon encapsulated Cu0/Cu+ catalyst.•In-situ reduction of Cu in low temperature APRM.•Excellent catalytic hydrogen production rate of ...46.15 μmol·gcat-1·s−1 at 190 °C.
The development of a highly efficient non-noble catalyst for rapid releasing of hydrogen from methanol/water at low temperature is urgent, but challenge. In this paper, the high content of graphited N-doped carbon encapsulated reducing state copper catalyst was fabricated for low-temperature aqueous reforming of methanol. The Cu@NGC-600 catalyst gives excellent hydrogen production rate of 46.15 μmol·gcat-1·s-1 at 190 °C, which is 4 times higher than the commercial 20 % Pt/C catalyst and 3 times higher than other reported Cu-based catalysts (such as the Cu@NC-200 catalyst). Characterization and DFT calculation results revealed that rich doping of graphite N and the synergistic effect of Cu–N strengthened the electron transfer between copper and the NC matrix, decrease the reduction temperature of catalyst, which enabled the Cu to maintain a highly reduced state of Cu0/Cu+ during APRM for low temperature (150–190 °C) hydrogen production.
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•Mo-doped engineering Ni for synthesis of bio-jet fuel precursor from bioethanol.•High performance is owing to Ni electron cloud density reduction and amphipathy.•Hydrophilicity can ...promote the higher alcohol reacting on Ni and alkaline sites.•DFT reveals the energy barrier of ethanol upgrading reaction at active sites.
Direct upgrading of aqueous bio-ethanol into higher alcohols is an emerging and highly attractive protocol to produce bio-fuels. However, it remains a great challenge to achieve high yield and selectivity of long-carbon chain higher alcohols, especially for C8+ alcohols. Herein, the carbon encapsulated NiMo catalysts were designed and fabricated for direct upgrading of aqueous bio-ethanol. The NiMo@C catalyst with Ni/Mo ratio of 6/1 exhibited excellent performance with 89.4 % of bio-ethanol conversion and 42.1C-mol% of higher alcohols yield. The selectivity of C8-16 products reached 44.7 %, which can be directly hydrodeoxygenated to produce bio-jet fuels. Characterization and DFT calculation results revealed that the doping of Mo tuned the electronic state of Ni and modified the surface properties (i.e., hydrophilicity, lipophilicity, and OH− adsorption), which enhanced the interaction of active site (NiMo-OH−) with intermediate aldehyde in the oil phase and promoted secondary upgrading reaction to form C8-16 alcohols. This work provides a promising approach to produce bio-jet fuels by direct upgrading of biomass fermentation ethanol.
•The AcMPS and EnMPS showed potential anti-oxidant effects.•The polysaccharides have hepatoprotection by remitting hepatic enzymes activities.•Findings indicate the bioactivities are related to ...physical-chemical characteristics.•The polysaccharides could be functional foods and natural drugs for preventing ALD.
The present work investigated the antioxidant and hepatoprotective effects of acidic- and enzymatic-hydrolysis mycelium polysaccharide (AcMPS and EnMPS) from Pleurotus geesteranus on alcoholic liver disease (ALD) mice. The animal studies demonstrated that the polysaccharides had potential effects reflected by remitting alcoholic hepatitis, reducing lipid accumulation, preventing oxidative stress, improving inflammatory symptoms, and alleviating the liver functions by histopathologic observation. Results showed that AcMPS (yield of 84%) was composed of L-Rha, D-Rib, L-Ara, D-Glc, D-Man and D-Gal with the Mw of 3.49 × 104 Da, while EnMPS (yield of 90%) was contained L-Rha, L-Ara, D-Gal and D-Glc with the Mw of 3.67 × 104 Da. Furthermore, the GC–MS analysis indicated that both AcMPS and EnMPS were β-pyranoside polysaccharides with the (1→3)- and (1→6)-linkages. The conclusions indicated that AcMPS and EnMPS could be used as natural drugs for preventing the ALD, and providing underlying hepatoprotective mechanisms, pharmaceutically.
The demand for surface wear-resistant metal components is increasing, but the current traditional preparation method of surface heat treatment for forgings and castings can hardly satisfy the trend ...of green development. In this study, we developed wire arc additive manufacturing laser cladding (WAAM-LC) hybrid manufacturing technology for the integrated preparation of 304 component with Ni60B reinforced coating. The microstructure and mechanical properties of 304 WAAM entity and Ni60B coating were systematically investigated. The results show that a good metallurgical bond is achieved between the Ni60B coating and 304 substrate. Both γ-Fe and δ-Fe phases appear in the 304 WAAM region, and γ-(Ni,Fe), FeNi
3
, (Cr,Fe)
m
C
n
, and Ni
m
Si
n
phases are detected in the Ni60B LC coating. Slender columnar crystals and cellular crystals coexist in the 304 bonding region, while the bottom of the Ni60B coating consists of plane crystal and columnar crystals. Both molten pools appear to have a haphazardly growing dendrite structure inside. Compared to the 304 substrate, the hardness of Ni60B coating increases by 2.76 times, and the friction and wear mass loss is only 10.54% of the 304, significantly improving the wear resistance of the 304 substrate. This work indicates that WAAM-LC hybrid technology is expected to become a promising new solution for manufacturing surface wear-resistant metal components.
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