Explore the vast range of titles available.

Lignocellulosic biomasses derived from dedicated crops and agro-industrial residual materials are promising renewable resources for the production of fuels and other added value bioproducts. Due to the tolerance to a wide range of environments, the dedicated crops can be cultivated on marginal lands, avoiding conflict with food production and having beneficial effects on the environment. Besides, the agro-industrial residual materials represent an abundant, available, and cheap source of bioproducts that completely cut out the economical and environmental issues related to the cultivation of energy crops. Different processing steps like pretreatment, hydrolysis and microbial fermentation are needed to convert biomass into added value bioproducts. The reactor configuration, the operative conditions, and the operation mode of the conversion processes are crucial parameters for a high yield and productivity of the biomass bioconversion process. This review summarizes the last progresses in the bioreactor field, with main attention on the new configurations and the agitation systems, for conversion of dedicated energy crops (Arundo donax) and residual materials (corn stover, wheat straw, mesquite wood, agave bagasse, fruit and citrus peel wastes, sunflower seed hull, switchgrass, poplar sawdust, cogon grass, sugarcane bagasse, sunflower seed hull, and poplar wood) into sugars and ethanol. The main novelty of this review is its focus on reactor components and properties.

Cultivation of plant cell cultures in conventional bioreactors designed for microbial cells often results in decrease of biomass productivity as compared to that in shake flasks, presumably due to the imbalance between the mass transfer requirements and compromise with cell viability. Hit and trial methods for bioreactor design are generally performed to achieve high biomass productivity in the bioreactor. In this study, a rational approach has been adopted to choose a suitable impeller for Viola odorata cell suspension culture using computational fluid dynamics (CFD). A two-phase CFD model was employed to characterize the non-Newtonian fluid dynamics of the plant cell suspension in a stirred tank reactor using different impeller designs, a setric, Rushton and marine impeller. The simulations were performed adopting Euler-Euler approach for the two-phase flow and dispersed turbulence model. The numerical model was validated with good agreement with experimental determination of volumetric mass transfer coefficient. The impact of impeller design was then investigated on critical process parameters like mixing, oxygen mass transfer and shear. The developed CFD model demonstrated that setric impeller is a suitable choice for V. odorata cell cultivation among the three impellers offering low-shear environment at equivalent velocity magnitudes at reactor bottom with higher cell-lift capabilities which is preferable in high cell-density plant cell cultivations.

This study presents a SHAP-based adaptive multi-objective optimization method for centrifugal pump impellers. By integrating OLHS, a BPNN surrogate model, and NSGA-III, the approach overcomes traditional “black-box” limitations and computational inefficiency. SHAP values quantify design variable contributions to head, efficiency, radial and axial forces, and torque, guiding an adaptive hybrid sampling strategy. Pareto-optimal solutions are selected via TOPSIS. The optimized impeller achieves an 11.07% increase in head, a 3.7% improvement in efficiency, and a 46.4% reduction in radial force.

The successful design and operation of solid-liquid agitators require proper prediction of critical impeller speed (Njs) needed to suspend solids. It depends on system and impeller geometry as well as the properties of both solid and liquid. In this research, the effect of impeller blade thickness on Njs required for complete suspension of solid particles was discussed. Experiments were performed in an agitated vessel of 0.29 m diameter with three impellers namely Rushton turbine (RT), Pitched blade turbine (PBT) and A320 impeller. The impeller thickness was varied as 1, 2, 3 and 4 mm. The results showed that with the increase in impeller blade thickness, the critical impeller speed decreased significantly and the power required for complete suspension increased. Modifications are made in the Zwietering correlation by considering the effect of the impeller blade thickness to improve the prediction of critical impeller speed.

The ultra-low specific speed high-speed centrifugal pump with circular hole flow channel impeller is experimentally studied. The test results show that when the circular hole flow channel impeller is furnished with a sealing ring, the head of the pump is about 2% lower compared to the situation without a sealing ring. The efficiency is increased by 1.66% to 4.68%. Different throat diameters correspond to different parameter ranges. It is seen that with the increase of the throat area ratio, the allowable working range of the pump shifts towards the direction of larger flow rates, during which the maximum efficiency value gradually grows. The flow-head performance of these high-speed pumps with impellers of circular hole flow channels conforms to the similarity conversion law of pumps. The results also show that when the rotational speed rises from 8,964 rpm to 14,560 rpm, the efficiency at the similar working condition points of the pump can be enhanced by approximately 1%.

For the inverse designs of centrifugal and mixed-flow pump impellers, clarifying the generation process of secondary flows and putting forward corresponding suppression measures is an important approach to improve the impeller performance. In this paper, to provide a better qualitative insight into the generation mechanism of secondary flows in the impeller, a simple kinematic equation is derived based on the ideal assumptions, which indicates that the potential rothalpy gradient (PRG) is the most important dynamic source that actively induces secondary vortical flows. Induced by the natural adverse PRG on the S1 and S2 stream surfaces, two typical secondary flows, H-S and P-S secondary flows, are clearly presented. To specially suppress these typical secondary flows, a general alternate loading technique (GALT) is proposed, aiming to adjust the real blade loading δp to control the PRG features. At the blade fore part, the δp on the hub streamline should be slowly increased to avoid breakneck growth of the potential rothalpy to reduce adverse streamwise PRG on the S2 streamsurface. At the blade middle part, the δp should be moderately decreased to reduce adverse streamwise PRG on the S1 streamsurface. At the blade aft part, the difference in the δp between the shroud and hub streamlines should be decreased faster to control the exit uniformity. By applying the GALT to the impeller designs of three typical pump types in hydraulic engineering, the organizational effect of the PRG on fundamental flow structures is proven. The GALT can effectively control the PRG distributions and suppress the secondary flows, thereby widening the pump’s high-efficiency zone, improving flow uniformity and suppressing pressure fluctuations. Compared with the current Z-G method and the ALT, the GALT can meet the requirements of “de-experience” better, thereby enabling the designers to obtain good products explicitly and quickly.

In the centrifugal pump, cavitation often leads to the noise and pressure pulsation, further affects the performance and operation of the pump. Therefore, it is essential to improve cavitation performance at the stage of pump design. In this paper, three centrifugal pump impellers are designed by using different inlet geometry, where one is the conventional type and has cross section diffusion of flow passage along flow direction, and other two impellers are proposed and have cross section contraction of flow passage from impeller inlet to exit. For comparison of cavitation performance, the three-dimensional cavitating turbulent flows are simulated using the RANS method for the pumps. The results show that the pumps with the proposed meridional section have much better cavitation performance at design point while their hydraulic efficiency is also improved at larger flow rate, compared with that with the conventional meridional section design. Extending the blade leading edge of the proposed impeller is very helpful to obtain better cavitation performance further due to the uniform flow and smaller pressure drop around impeller inlet.

Through the analysis of the wide and efficient mechanism of centrifugal pump, this paper finds that the shape of the blade inlet angle to the outlet angle distribution line of the centrifugal pump impeller within the blade wrapping angle is the key factor determining the width and efficiency. Two sets of blade thickening laws are adopted, namely the equal thickness type and the NACA1933 air-foil. Tests have shown that the hill-type is superior Linear scheme, NACA1933 air-foil blades are superior to equal-thickness blades. The hill-type solution achieves the performance indicators of wide and efficient centrifugal pumps. Firstly, the angle distribution line of the inlet angle to the outlet angle of the pump is designed, and the calculus equation is applied to solve the conformal transformation line in the square grid, so as to produce a wide and efficient centrifugal pump impeller profile. The design method is applied to different specific speed centrifugal pumps, and the test results show that this method achieves the purpose of wide and efficient centrifugal pump, reaches the international advanced level, and provides a new method for the hydraulic design of centrifugal pump.

Gas-inducing reactors (GIRs) are widely used in applications where external gas recycling is unsafe or operationally restricted, yet quantitative design guidelines for impeller–stator geometry remain scarce, despite its strong influence on gas dispersion and retention. This study investigates the effects of stator blade number and blade thickness on gas holdup in a double-impeller GIR using a three-dimensional Euler–Euler CFD framework. Stator configurations with 12–48 blades and blade thicknesses of 1.5–45 mm were examined and validated against experimental data, with gas holdup predictions agreeing within 5–10%. The results show that the stator open-area fraction (ϕA) is the dominant geometric parameter governing the balance between radial dispersion and axial confinement. High-ϕA stators (fewer, thinner blades) enhance bulk recirculation and bubble residence time, increasing gas holdup by up to ~20% relative to dense stator designs, whereas low-ϕA stators suppress macro-circulation, promote axial gas transport, and reduce holdup despite higher local dissipation near the rotor–stator gap. A modified gas-holdup correlation incorporating ϕA is proposed, yielding strong agreement with CFD and experimental data (R2 = 0.96). Torque analysis further reveals competing effects between impeller gassing, which lowers hydraulic loading, and increased flow resistance at low ϕA, which elevates torque. Overall, the results provide quantitative guidance on how stator blade number and thickness influence gas holdup, enabling informed stator design and optimization in GIRs to improve gas dispersion through rational geometric selection rather than trial and error approaches.

Helical ribbon impellers are commonly used for mixing high‐viscosity fluids, but they are expensive to manufacture. To address this, the authors developed the Advanced Mixing (AM) impeller, which demonstrated higher mixing efficiency compared to other high‐viscosity impellers. In a subsequent study, the authors explored reducing the number of basic components in the AM impeller to further lower costs. The development process of the AM impeller and its high mixing efficiency have been described in detail in our previous studies (Furukawa et al., 2023, 2025), and the present results further demonstrate the consistent high performance of this impeller. Meanwhile, many multistage impellers for high‐viscosity applications, produced by both domestic and international manufacturers, feature blades arranged with a 90‐degree phase shift. Therefore, the authors evaluated the performance of the AM impeller using the same configuration. They found that using the concept of pitch ratio allows for the simultaneous evaluation of the number of stages and phase, enabling the determination of the optimal configuration for the AM impeller.