| 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. |
- Liu, Baoqing, et al.
(författare)
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Experimental investigation on micromixing characteristics of coaxial mixers in viscous system
- 2020
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Ingår i: Canadian Journal of Chemical Engineering. - : Wiley. - 0008-4034 .- 1939-019X. ; 98:8, s. 1815-1824
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Tidskriftsartikel (refereegranskat)abstract
- An experimental investigation into the micromixing performance of coaxial mixers in a viscous system is reported, in which the iodide-iodate reaction system is chosen to quantitatively characterize the product distributions. The effects of feeding time, feeding position, impeller speed, inner impeller configuration, and operation mode on the segregation index, Xs, are examined. It is revealed that the feeding near the inner impeller benefits micromixing and should be regarded as the preferred position. The presence of the rotating outer impeller causes the micromixing performance of the coaxial mixer to be significantly better than the single-shaft mixer. While an increase in the outer impeller speed has a limited influence on micromixing, the inner impeller speed is the dominant influencing factor, that is, the Xs decreases obviously when the inner impeller speed is increased. On the other hand, the coaxial mixers with multiple and axial inner impellers have a better micromixing performance at the same specific power consumption, PV, than that with single and radial inner impellers. Among the configurations consisting of a Rushton impeller (RT), six-straight-blade turbine impeller (SBT), and six-pitched (45°)-blade turbine impeller (PBT), the Xs of the coaxial mixer is always the smallest at the same PV when the PBT + RT configuration is used as the inner impeller. In addition, it is found that the difference in Xs that results from various operation modes is small in terms of power consumption; however, the co-rotation mode is still recommended for the micromixing of the coaxial mixer due to its excellent performance in general.
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| 3. |
- Liu, Baoqing, et al.
(författare)
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Numerical Investigation and Estimating Correlation of Micromixing Performance of Coaxial Mixers
- 2019
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Ingår i: Industrial and Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 58:49, s. 22376-22388
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Tidskriftsartikel (refereegranskat)abstract
- In view of the significance, complexity, and difficulty of micromixing in viscous system, coaxial mixers with wide adaptability to viscosity are first combined with micromixing. The effects of feeding position, rotation mode, and impeller type on the micromixing performance of coaxial mixers are investigated numerically with the standard engulfment model and eddy dissipation concept model, and a dimensionless estimating correlation of segregation index Xs is established based on the Buckingham πtheorem. The results show that feeding near the discharge zone of the impeller favors the micromixing and Rushton turbine impeller (RT) is better qualified as the impeller near feeding point compared to six-straight-blade turbine impeller (SBT) and six-pitched (45°)-blade turbine impeller (PBT). At the same specific power consumption, the coaxial mixer has better micromixing performance with PBT + RT as inner impeller than with SBT + RT, and the difference of segregation index resulting from the rotation mode is small. Moreover, the proposed correlation is validated to be suitable for qualitative evaluation of micromixing performance of coaxial mixer consisting of inner impeller combining PBT and RT and outer anchor.
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| 4. |
- Xu, Zilong, et al.
(författare)
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Experimental investigation on solid suspension performance of coaxial mixer in viscous and high solid loading systems
- 2019
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Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509. ; 208
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Tidskriftsartikel (refereegranskat)abstract
- The coaxial mixers consisting of an inner Rushton turbine or propeller and an outer anchor were combined first with the just off-bottom suspension in viscous and high solid loading systems. In this study, a new method based on RGB brightness analysis was proposed to determine the cloud height, and the measures to promote cloud height were also discussed. In addition, the effects of rotation modes, pumping modes and solid loading on the just-suspension power were investigated. The results showed that the co-rotation coaxial mixers with an up-pumping inner impeller could achieve the just suspension at lower power consumption and were recommended. The combination of anchor and up-pumping propeller was the most energy efficient among the investigated mixers, whereas its cloud height was relatively low. The high off-bottom clearance and the combined inner impeller could promote the cloud height with little power variation, but the enlargement of inner impeller had no obvious effect.
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