Influence of Cross-Sectional Flow Area of Annular Volute Casing on Transient Characteristics of Ceramic Centrifugal Pump

The annular volute is typically used in a slurry pump to reduce the collisions between solid particles and the volute tongue and to achieve a better resistance to blocking. However, only limited studies regarding annular volutes are available, and there is no systematic design method for annular volutes. In this study, the influence of volute casing cross-sectional flow area on the hydraulic loss, pressure pulsations, and radial force under varying working conditions in a centrifugal ceramic pump are discussed in detail. Experimental tests were conducted to validate the numerical results. The results indicated that, when the volute casing flow area increases, the hydraulic performance decreases marginally under the rated working conditions, but increases at the o-design points, specifically under large flow condition. However, the volute casing with a larger flow area has a wider high-e ciency region. In addition, the increase in the volute casing flow area will decrease the pressure pulsations in the volute, regardless of the working condition, and decrease the radial force on the shaft, therefore, providing an improved pump operational stability. It is anticipated that this study will be of benefit during the design of annular volutes.

Common-mode Electromagnetic Interference Mitigation for Solid-state Transformers

Solid-state transformers(SSTs)have been widely used in many areas owing to their advantages of high-frequency isolation and high power density.However,high-frequency switching causes severe electromagnetic interference(EMI)problems.Particularly,the common-mode(CM)EMI caused by the switching of the dual active bridge(DAB)converter is conducted through the parasitic capacitances in the high-frequency transformer and impacts the system reliability.With the understanding of the CM EMI model in SSTs,CM EMI mitigation methods have been studied.For passive mitigation,the coupled inductor can be integrated with the phase-shift inductor function to reduce CM EMI.For active mitigation,variations in the DAB switching frequency can help reduce the CM EMI peak.An active EMI filter can also be designed to sample and compensate for CM EMI.Using these methods,CM EMI can be reduced in SSTs.

Coordination behavior between zinc salts and L-α-methionine

The solubility properties of ZnCl\-2/ZnAc\-2/ZnSO\-4MetH\-2O systems at 25℃ in the whole cocentration range have been investigated by phase equilibrium method. The results indicate that ZnAc\-2 and ZnSO\-4 systems are both simple systems, which do not exist any compound; there are 2 complexes formed in ZnCl\-2 system: Zn（Met）Cl\-2 and Zn（Met）\-2Cl\-2·2H\-2O. Under the direction of phase equilibrium result, 2 solid complexes have been prepared in water and characterized by chemical analysis, IR, Xray diffraction. Their combustion energies have also been determined by means of a RBCtype1 rotatingbomb calorimeter, and their standard enthalpies of formation, Δ f, coor（s）H O-, have been calculated which are （-828.32±3.00） kJ·mol -1 and （-1 117.08±6.15） kJ·mol -1, respectively.