Single-phase AC-AC converters using power MOSFETs

The authors analyze the performance of a single-phase AC-AC converter with particular emphasis on the output harmonic content and input voltage utilization. A complete power circuit that makes use of power MOSFETs is given. An analysis of the output waveform shows that its harmonic content is very low. It is also found that the ratio of the switching frequency to the modulating triangular wave, has negligible effect on the harmonic content. Hence, the ratio can be chosen at nominal value of 4 and it is mainly used to control the amplitude of the fundamental component in the output. The only disadvantage of the single-phase AC-AC converter is that the amplitudes of certain harmonic frequencies become abnormally high     

Emission and performance study emulsified orange peel oil biodiesel in an aspirated research engine

This study paves the way on reducing smoke emission and NO_x emissions of research diesel engine by detailing the effect of water addition in biodiesel. Fuel samples were prepared with different concentrations of water in orange peel oil biodiesel (94% waste orange peel oil biodiesel + 4% water + 2% Span 80 (WOPOBDE1) and 90% waste orange peel oil biodiesel + 8% water + 2% Span 80 (WOPOBDE2). Span 80 was employed as a nonionic surfactant, which emulsifies water in biodiesel. Experimental results revealed that the nitrogen oxides and smoke emission of orange peel oil biodiesel emulsion were reduced by 11%–19% and 3%–21%, respectively, compared to that of neat orange peel oil biodiesel (WOPOBD). In addition, the introduction of orange peel oil–water emulsions in the diesel engine considerably reduced the emissions of unburned hydrocarbons and carbon monoxide. The overall hydrocarbon emission of WOPOBDE2 was 12.2% lower than that of WOPOBD and 16.3% lower than that of diesel. The overall CO emission of WOPOBDE2 was 17% lower than that of base fuel (WOPOBD) and 21.8% lower than that of diesel. Experimental results revealed that modified fuel had higher brake thermal efficiency and lower brake specific fuel consumption than that of base fuel at all engine brake power levels.     

Influence of conical strip inserts in heat transfer enhancement under transition flow

ABSTRACT

The performance of the concentric tube heat exchangers can be increased due to the swirl flow generation caused by the inserts which exchange heat in an effective manner. Many researchers have studied the thermal behaviour of different types of inserts, such as twisted tape and wire coil, with different geometries. This work dealt with the heat transfer and friction factor behaviour of newly fabricated staggered and non-staggered conical strip insets. The conical strip insert produces much swirl flow corresponding to the twist ratios (Y?=?2, 3 and 5). The experimental results are in good agreement with the correlations developed for Nusselt number and friction factor with the help of regression analysis.     

A novel feature selection framework based on grey wolf optimizer for mammogram image analysis

Neural Computing and Applications - Breast cancer is one of the significant tumor death in women. Computer-aided diagnosis (CAD) supports the radiologists in recognizing the irregularities in an...     

CFD simulation analysis of two-dimensional convergent-divergent nozzle

ABSTRACT

Computational fluid dynamics is one of the parts of fluid mechanics and calculating numerical methods are solving the various flows of fluid. Two-dimensional models, which is to solve the flow rate of supersonic flow and analyzed the mathematical operations, which has solved the energy equations. This iteration process has analyzed and shown better results of temperature and static pressure, velocity, static temperature. The investigating results showing better temperature and velocity flows. The 2D nozzle line diagram is done in Ansys 14.5 geometry modular and calculated iteration process can be done in fluid flow. The nozzle is done and meshes using automatic method and sizing of different value of the meshing process. In the order to analyzed the Ansys fluent software and solved the flow process of the convergent-divergent iteration nozzle. Standard nozzle equation manually calculated and compared with analyzing the results.     

Analysis of Commutation of a Current Inverter Feeding an Induction Motor Load

A method for analyzing the performance of an induction motor fed from a current source inverter and especially for computing the currents during commutation of the inverter is presented. A mathematical model of an inverter-fed induction motor is given in terms of Park's vector. Based on this model a closed form time domain expression is developed for the current during commutation. The stator voltage of a current-controlled inverter-fed induction motor is shown to be almost sinusoidal with superimposed spikes during commutation of current. The computed performance of the machine is verified experimentally, and there is a very close agreement between the computed and test results. The method presented also provides information regarding the voltages across the commutating capacitors and thyristors based on which proper selection of the thyristors and commutating capacitors can be made.     

A doubly-fed induction generator-based wind generation system with quasi-sine rotor injection

Wind generating systems use doubly-fed induction generators (DFIGs) to achieve high conversion efficiency and to reduce the installation cost. The paper proposes and analyzes a simple DFIG-based wind generation system in which the excitation power is obtained from a photovoltaic (PV) panel and battery. The proposed scheme is suitable for small wind power systems for which a complex field orientation control is not justified. It can be used for stand-alone operation and also grid-tied operation. The rotor of the DFIG is applied with a quasi-sine wave instead of a sine wave. The operation and harmonic characteristics of the scheme are established using analysis, simulation, and experimentation. The details of the control circuit are given along with the experimental waveforms of voltages and currents and frequency spectra. The total harmonic distortion in the output current is found to be around 8%.     

CFD analysis of mixed convection porous square cavity

The analysis of conventional flow and transfer of heat in a square cavity which is porous in nature is being done by the numerical study and research. There is insulation at the vertical walls of the cavity and bottom surface wavy in nature upholds uniform temperature which is little more than that at the upper lid. The non-dimensional governing equations are solved using the finite volume method. Several inclination angles are examined from 0° to 180°. The isotherm and streamline distribution, including varieties of local and average Nusselt numbers with the angle of inclination, are exposed. The outputs of the observations indicate that average Nusselt number has direct relationship with a number of undulations and also inclination angle.     

A novel sine PWM scheme using waveform generators

The paper presents a novel circuit for generating the sine PWM control signals for a single phase inverter. Waveform generating ICs based on a JFET are used to generate the synchronized sine and triangular waveforms with a high accuracy and wide range of frequencies. Experimental waveforms and frequency spectra of inverter output voltage are presented     

Critical Examination of the Role of Silica Nanoparticle Dispersions in Heat Transfer Fluid for Solar Applications

Silicon - Silica nanoparticles are eco-friendly with high heat transfer potential due to their low-cost synthesis, abundant natural resources, and mass production. Silica nanoparticles with...