| 1. |
- Chen, Fuqiang, et al.
(författare)
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减压阀噪声研究进展
- 2019
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Ingår i: Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering. - 1674-8530. ; 37:1, s. 49-57
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Tidskriftsartikel (refereegranskat)abstract
- In order to comprehensively understand the specific noise generation process inside pressure reducing valves (PRV) and its existing research outcomes, the generation of noise in PRV with its research methods in China and abroad was summarized. Then, the current research status of noise reduction technologies was reviewed from two aspects: source and propagation. Based on analysis and summarization, the major existing problems in current noise reduction technologies were discussed, including complex flow situation in PRV, ambiguity of vortex location and uncertain of interaction between high-velocity jet flows and so on. In the future investigation of noise reduction in PRV, it is advised that the position of noise source in valve should be determined firstly through combination of theoretical analysis, experiment and numerical analysis. Then, the directivity of noise in the valve can be clarified. Thereby, a further study of noise reduction mechanism and technology can be launched. Finally, noise in PRV can be reduced to the utmost extent. In the future, control of noise inside PRV should start with flow mechanism and structural innovation, and then a universal valve design theory with low noise will be put forward. Investigation into noise characteristics in pressure reducing valve can provide a reliable basis for reducing noise effectively.
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| 2. |
- Wu, Angjian, et al.
(författare)
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Co-generation of hydrogen and carbon aerosol from coalbed methane surrogate using rotating gliding arc plasma
- 2017
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619. ; 195, s. 67-79
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Tidskriftsartikel (refereegranskat)abstract
- A novel atmospheric pressure non-thermal plasma, i.e., rotating gliding arc (RGA), is developed to upgrade coal bed methane (CBM) into hydrogen and carbon aerosol simultaneously. CH4 is used as a CBM surrogate. In present work, the V-I characteristics of RGA discharge in CH4 conversion are monitored with different gases (N2, Ar and CO2) as carrier gas, while the active species (such as OH, CH, CN, C2, excited molecules and ions) involved in the plasma reactions are identified by optical emission spectroscopy (OES). According to the sensitivity analysis of specific energy density (SED), the importance of operating conditions on SED sensitivity is in a sequence of CH4 concentration > applied voltage > residence time. The performance of CH4 conversions are comparatively evaluated based on the variation of operating conditions. In general, the enhancement of applied voltage and residence time effectively increases the CH4 conversions, selectivity of hydrogen, as well as the energy efficiency, while the augment of CH4 concentration has a negative effect in contrast. The carbon aerosol obtained in CH4/N2 and CH4/Ar discharge are comparatively investigated. Transparent crumped-like graphene sheets and spherical nanostructure carbon are observed in both obtained carbon aerosol, with relative high ID/IG ratios (∼0.62) indicated in Raman spectroscopy. High C/O ratios (>14) are obtained in the XPS survey spectra, with the intensity ratios of sp2 C[dbnd]C/sp3 C-C occupy about 80%. However, the BET surface area of carbon obtained from CH4/N2 is almost 3 times larger than that from CH4/Ar discharge. In addition, super hydrophobic and oleophilic properties are observed in both carbon samples. The contact angles of water droplets are above 130°, while the contact angle of oil is less than 4°.
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| 3. |
- Zhang, Jinyuan, et al.
(författare)
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Bi-level Optimization of Component Sizing and Energy Management in Fuel Cell Hybrid Electric Trucks
- 2023
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Ingår i: 2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023. ; , s. 202-207
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Konferensbidrag (refereegranskat)abstract
- Electric trucks powered by hydrogen fuel cells are a promising electrified transportation technology. To compensate for the relatively slow dynamics of fuel cells, lithium-ion batteries can be incorporated into the hydrogen power systems. This paper proposes a bi-level optimization framework for proper component sizing and energy management in fuel cell hybrid electric trucks. Based on the sizing variables at the upper level, the lower level utilizes convex programming to generate an optimal energy management solution and returns the solution to the upper level. Then, the upper level runs a particle swarm optimization process to determine the optimal sizes of the fuel cells and lithium-ion batteries to minimize the sum of the component costs and operating costs. By conducting a case study using a modified ACEA long-haul drive cycle, this paper demonstrates the effectiveness of the proposed framework.
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