Numerical analysis of the photovoltaic system inspection with active cooling

The use of solar energy may replace the present fossil fuel or gas to produce electricity. The goal of this study is to set up a simulation model to survey the performance of a photovoltaic thermal system (PV/T) based on the computational fluid dynamics (CFD) method. Ansys fluent software has been used for the simulation procedure. The electrical panel output and its efficiency were investigated numerically. In addition, the effect of variations in absorbed radiation on inlet fluid and absorber panel temperature on the system performance was investigated. The study was conducted for three cases, in a first case, where there is no refrigerant in the system and in the latter case, at constant fluid rate of the pump, whereas the third case with optimal pump operation. The numerical findings obtained from CFD simulators have been compared with the test records of the experimental results of the literature. The two results have a good agreement. From the obtained results, it can be noted that the system shows a good improvement for the electric net efficiency level of 3.52% with a lower reduction of the thermal system efficiency of 1.96% in comparison to the system when using the constantly high flow rate

The Influence of the Mixed Electric Line Poles on the Distribution of Magnetic Field

With the wide spread of the transmission lin

Measurement of the SAR Levels Near the Human Head for Different Types of Mobile Phone device

With the increasing of mobile phones users during the last decades , the potential adverse outcomes from exposure to electromagnetic fields (EMF) emitted from different types of these mobile phones has also been increased. In this work the measurement of electric field (EF) emitted from different types of mobile phone have been conducted and the Specific Absorption Rate (SAR) had been mathematically calculated for different types of mobile phones in different ranges from the human head . The comparison of measured levels with the international radiation exposure ICNIRP indicate that they are lay within the standards limits .that means there is no negative effect on human health from the exposure to these radiations if the exposure is for a short and discontinues period

Modeling of magnetic sensitivity of the metal-oxide-semiconductor field-effect transistor with double gates

In this paper, we investigated the effect of magnetic field on the carrier transport phenomenon in metal-oxide-semiconductor field-effect transistor (MOSFET) with double gates by examining the behavior of the semiconductor under the Lorentz force and a constant magnetic field. Various behaviors within the channel have been simulated including the potential distribution, conduction and valence bands, total current density, total charge density and the magnetic field. The results obtained indicate that this modulation affects the electrical characteristics of the device such as on-state current (ION), subthreshold leakage current (IOF), threshold voltage (VTh), and the Hall voltage (VH) is induced by the magnetic field. The change in threshold voltage caused by the magnetic field has been observed to affect the switching characteristics of the device, such as speed and power loss, as well as the threshold voltage VTh and (ION/IOF) ratio. Note that it is reduced by 10-3 V. 102 for magnetic fields of ±6 and ±5.5 tesla respectively

Study and analysis the effect of panel rear surface temperature on the photovoltaic system efficiency

As the operating temperatures increase, the efficiency of the solar system will be decreases. Therefore, the examination of the mode of transmission and dissipation of the temperature of the solar panel and its impact on the level of electricity generation of the panel has made a significant contribution to determining the solar panel efficiency. In order to reduce the possibility of excessive heating, in particular its upper part, so, leaving a certain air gap between the hatching roof surface and the panel back at which the solar panel can be allowed heat dissipation. The aim of this work is to study and investigate the impact of the solar panel rear surface temperature on its output. The study was performed experimentally on three heights (10, 20 and 30 cm) in 3 positions. The study was first carried out with three identical panels on one height of the roof, then ,the height of the first panel remains unchanged, while,  the other two panels being changed by 20 cm and 30 cm in the woe steps respectively. The results obtained show that the solar panel output level is inversely proportional to the panel rear surface temperature. So, we can conclude that in case of leaving a certain air gap will lead to more dissipation of panel heat which lead to a much increase in the panel output level.

Study and analysis the effect of the Circular Flat Spiral Coil Structure on the performance of the Wireless Power Transfer System

The proper selection of winding parameters for resonant circuits in inductive power transmission systems is an important issue, as it has a significant impact on system performance and power transmission, and these parameters can be optimized. Depending on the relationship between the coil design and the electrical parameters, the optimal number of coils can be selected for different criteria and protection conditions. This paper presents a method for calculating the geometrical and electrical parameters of planar coils used in parallel resonant systems for wireless power transmission (WPT) system, and for selecting the optimal number of coils. The equations for calculating the active resistance and inductance of the coils are normalized based on the given coil design parameters.. Practical examples of application of the selected method to transmitter and receiver windings of WPT systems are given. The obtained results indicates that the system performance and dissipated power are higher when windings with a calculated number of windings are provided. The proposed method can be used to choose the optimal design of toroidal coils in fixed frequency systems, as well as in systems where the operating frequency depends on the of the resonant circuit parameters

Investigate and Analyze the Electromagnetic Field Levels Inside Electric Power Substation

Electric power transformers are a very important part of modern electric power and transmission line network systems and they consider as a high level source of electromagnetic fields which can affect the health of workers in station.  In this research, electric and magnetic fields caused due to the operation of power distribution substation of 132/33 kV are investigated in order to avoid the overexposure of these fields to workers. Research has been conducted on both the mathematical calculations and practical measurements. The intensities of electric and magnetic fields have been measured at substation by EMF tester device. Safe zones from some equipment have been determined. Comparison the obtained results with the standard safety guideline limits shows that they are within the acceptable limits. DOI: http://dx.doi.org/10.25130/tjes.24.2017.26 </p