Mohammed A. Bou-Rabee

Improving the Overall Efficiency for DC/DC Converter with LoV-HiC System

It is very important to improve the overall efficiency of systems with a source of power that has low-voltage high-current terminal characteristics such as fuel cells. A resonant converter is required for high efficiency systems. However, the peak value of the switches current is large in a resonant converter. This peak current requires a large number of switches and results in system failures. In this paper, an analysis and experiments of a resonant isolation push-pull converter are performed. A switching loss analysis is performed in order to compare losses between a resonant push pull converter and a hard switching push-pull converter. Specially, the conduction loss is studied based on the ratio between the resonant frequency and the switching frequency. In addition, a method for improving the efficiency is implemented with conventional HF insolation converters.

A photovoltaic power-generation system with peak power cut function

This paper presents a photovoltaic-peak power-cutting (PV-PPC) system capable of cutting peak load power. The proposed system is composed of a PV generator, DC–DC converter, storage battery, and an inverter. The function of the proposed PV-PPC system is to use PV energy to cut the peak load power in response to the change in the load demand and generating power. Four possible power flow scenarios are examined in detail through the bidirectional operation of the DC–DC converter and inverter, through the charging and discharging of the battery. The suggested PV-PPC system operation algorithm first selects the operational state by using differentiated charge and load information, with a simple structure to enable stopping in the case of system failure, and operates depending on the selected state. Then, the analysis modelling and operational control algorithm of the PV-PPC-generation system are performed in detail. Finally, the simulation and experimental results are presented to confirm the validity of the system.

Particle tracking velocimetry investigations on density dependent velocity vector profiles of a swirling fluidized bed

ABSTRACT Swirling fluidized bed (SFB) is a newer version of the well-known bubbling bed and very little know. An insight study is therefore required for complete understanding of the hydrodynamics of a SFB operation. The current study was conducted on stable regime of a SFB operated at different blade fin angles, blade inclination angles, particle densities and superficial air velocities. Roughly one quarter of the fluidized bed was photographed and its velocity vector field plots were generated using a MATLAB supported particle tracking velocimetry (PTV) technique. At lower superficial velocities, Gaussian distribution of the velocity vectors was predicted along the radius of the bed. Particles in the vicinity of the bed walls moved relatively slower than those marching in the middle of the bed. However, at higher superficial velocities, the particles closer to the cone boundary were moving with velocities comparable to the particles in the middle of the bed. Unlikely, the particles closer to the outer bed wall kept on moving with lower velocities regardless of increasing superficial air velocity. A further look into individual velocity vector profiles revealed negligible influence of smaller blade angles (9° and 12°) on particles’ motion. The overall velocity magnitude decreased by 6% with 3° increase in blade fin angle and by 9% with 5° increase in inclination angle. Contrarily, the particle velocity underwent a monotonic decrease with particle density.