Two-phase Arrangement Research Articles

Prototype of a Two-Phase Axial-Gap Transverse Flux Generator Based on Reused Components and 3D Printing

This paper presents a prototype of a low-cost two-phase axial-gap transverse flux generator, in which the magnetic and electric circuits have been made of reused materials, and the stator housing has been manufactured by 3D printing of plastic. Therefore, this work presents as a novelty the combination of the novel transverse flux topology and two challenging trends in electrical machines manufacturing, such as reusing of components and additive manufacturing. Axial-gap transverse flux machines potentially enable the combination of two of the main advantages of axial flux machines and transverse flux machines, i.e., short axial length and a high number of poles. The two-phase arrangement with shared air gap is of great interest in order to reduce further the axial length while avoiding the use of magnetic materials in the rotor, such as iron or soft magnetic composites. However, the equivalent air gap might be large, with significant leakage and fringing effects as the magnetic flux closes through the air. Therefore, in this paper the accuracy of the analytical equations and the magnetic equivalent circuit is firstly investigated. The two-phase axial-gap transverse flux machine is prone to misalignment between phases and rotor imbalances that alter the air gap length, so these effects have been included in the simulations with the finite element method. Experimental tests have been conducted throughout the investigation, from the prototype characterization to the steady-state operation, both with no load and with resistive loads.

Two-Phase System for Generating a Higher-Frequency Rotating Magnetic Field Excited Causing Hyperthermic Effect in Magnetic Fluids

This article presents a new method of excitation for a fast-changing rotating magnetic field (RMF) of higher frequencies (HF) causing the hyperthermic effect in magnetic fluids. The method proposed here uses a magnetic field exciter (inductor) consisting of a ferrite magnetic circuit and a system of coils connected in a two-phase arrangement. The proposed system is powered by two higher-frequency rectangular signals, with a 90-degree phase shift between each other, through HF transformers with ferrite cores. This paper presents the outcomes of the operation of RMFs in the frequency range of 38 kHz to 190 kHz, with a value of amplitude of magnetic field intensity H equal to 20 kA/m and increasing temperature, in a sample of APG513 magnetic liquid. The obtained results show that, in the range of the magnetic field intensities of moderate values, at a constant frequency f, the values of the time derivative of temperature are proportional to the square of the magnetic field intensity dT/dt~H2. Moreover, the values of the temperature rate, which are measured with the constant value of the magnetic field intensity, are proportional to the square of the frequency dT/dt~f2. At higher amplitudes of the RMF, the relationship dT/dt~H2 is no longer fulfilled, and an inflexion point of this function appears. In the case of the highest values of the achieved intensity amplitudes (H = 20 kA/m), the parameter of the Langevin function achieves a value equal to ξ = 6.

Sorbic alcohol hydrogenation

Hydrogenation of sorbic alcohol was carried out in homogeneous, two-phase and heterogeneous arrangements. The effects of the reaction conditions on the reaction rate and the selectivity were studied. The highest selectivity was reached using ethylene glycol as the solvent and in two-phase arrangement, in which ethylene glycol was used as the catalyst phase.

Oxidation of 4-Methylanisole by Aqueous Cerium(IV) in a Two−Phase Immiscible Liquid/Liquid System: Interfacial versus Homogeneous Control

The kinetics of the oxidation of 4-methylanisole (MA) by Ce(IV) have been measured in both two-phase (MA/aqueous sulfuric acid) and single-phase (aqueous sulfuric acid) arrangements by using microelectrochemical measurements at expanding droplets (MEMED) and UV−visible spectrophotometry, respectively. In the two-phase arrangement, the electron transfer (ET) reaction appeared to occur interfacially, rather than by dissolution of MA followed by reaction in solution as previously considered. The effective first-order rate constant for the consumption of Ce(IV) at the interface is 2.0 × 10-4 cm s-1. The homogeneous reaction is first-order in both Ce(IV) and MA, with a rate constant for the loss of Ce(IV) of 1.0 mol-1 dm3 s-1. The lifetime of the 4-methylanisole radical cation in aqueous sulfuric acid, formed in the first step of the oxidation process, has been measured independently as ∼10 ms using steady-state ultramicroelectrode voltammetry. The factors leading to the different energetics of the one phase a...