The objective of this paper is to obtain an excellent structure of a rotational Hydrodynamic cavitation Reactor (RHCR) by a numerical method and then to investigate the cavitating flow characteristics of the optimized RHCR experimentally. The RNG k-ε turbulence model combined with the Zwart cavitation model was applied to analyze the influence of the straight blade number, the baffle position and the baffle shape on the pressure field, bubble distribution and turbulence kinetic energy of the RHCR. The results show that compared to the original model, an RHCR with a straight blade number of 6, a baffle position of 0. 74 and a triangular baffle offers better cavitation performance. Moreover, the energy performance and the cavitation development process of the optimized RHCR were studied experimentally. The results indicate that the multiscale bubbles are induced by straight blades and baffles of the optimized RHCR, accompanied by the twice quasi-periodic shedding dynamics in one cycle. The findings of this study have positive significance for the design and optimization of RHCRs.

Biodiesel is a bio-renewable fuel derived from vegetable oils and animal fats with less environmental pollution than fossil fuels. This research aims to design, fabricate, and evaluate a Hydrodynamic Reactor for biodiesel production. According to the fluid characteristic, the rotor and stator were designed and the electric engine was chosen. The cavities of the rotor were designed for optimal cavitation. The effect of reaction time and rotational speed were examined to assess the Reactor. Speed rotor rotational speed of Hydrodynamic cavitation Reactors can intensify the transesterification reaction by increasing the occurrence of cavitation in the space between the rotor and the stator. Therefore, to investigate the effect of this variable on biodiesel production efficiency, three levels were selected (2000, 2500, and 3000 rpm). As the rotational speed of the Hydrodynamic Reactor increases, the cavitation operation increases, and as a result, the conversion percentage rises too. This experiment indicated that the rise of residence time from 30 s to 60 s increases methyl esters yield, but following the time up to 60 s, the methyl esters yield has no significant changes. The results showed that the biodiesel produced from waste oil in the Hydrodynamic Reactor could be a suitable alternative to diesel.

Anaerobic baffled Reactor (ABR) consists of a series of continuous chambers divided into two up flow and down flow parts by a baffle. ABR could effectively purify high strength wastewater types with negligible surplus sludge and doesn’t need a settlement tank [1]. ABR is a treatment system based on its Hydrodynamic characteristics and so, the Hydrodynamic study of the current flow is an important issue about it. In this study, the Hydrodynamic characteristics of the Reactor are investigated. Also, the regime of passing flow is discussed.

Biomass is a renewable and sustainable energy source. Co-firing of biomass with coal will increase the renewable energy share by decreasing the coal consumption. In the present paper, Hydrodynamic behaviour of coal and biomass mixture is investigated in a fluidized bed Reactor. A Computational Fluid Dynamic (CFD) model is developed and the Hydrodynamic behaviour of gas and solid is investigated in detail. The CFD model is based on Eulerian-Eulerian multiphase modelling approach where the solid phase properties are obtained by applying the Kinetic Theory of Granular Flow (KTGF). Six different weight percentages of coal and biomass (100: 0, 95: 5, 90: 10, 80: 20, 70: 30 and 50: 50) are used for the present study. The Hydrodynamic behaviour is analyzed in terms of the important Hydrodynamic parameters like bed pressure drop, bed expansion ratio, particle volume fraction distribution and velocity distribution. The numerical model is also validated by comparing some of the numerical results with our own experimental data generated in a laboratory scale bubbling fluidized bed Reactor.