PERFORMANCE EVALUATION OF LIQUID-COOLED PHOTOVOLTAIC SYSTEM USING NUMERICAL METHOD

The purpose of present study is establishing a simulation model to consider the performance of a water photovoltaic thermal system (PV/T) via the computational fluid dynamics method (CFD). The proposed model includes a water riser tube and an absorber plate to consider the conduction and convection heat transfer mechanisms. The simulation process was carried out in the ANSYS FLUENT software. The effects of two different parameters on the efficiency and performance of the system were investigated numerically. The performance of the PV/T system versus the changes in the absorbed radiation on the plate and the fluid inlet temperature were analyzed. The temperature distribution of different sections of the system was obtained. For validation of the presented method, a comparison study was carried out with the experimental results in the literature; satisfactory convergences were found between the measured data and the experimental results

Evaluation of clustering role versus Brownian motion effect on the heat conduction in nanofluids: A novel approach

In this study, the temperature and viscosity-dependent methods were used to identify the main heat conduction mechanism in nanofluids. Three sets of experiments were conducted to investigate the effects of Brownian motion and aggregation. Image processing approach was used to identify detailed configurations of different nanofluids microstructures. The thermal conductivity of the nanofluids was measured with respect to the dynamic viscosity in the temperature range between 0 and 55 °C. The results clearly indicated that the nanoparticle Brownian motion did not play a significant role in heat conduction of nanofluids, which was also supported by the observation that a more viscous sample rendered a higher thermal conductivity. Moreover, the microscopic pictures and the differences in the viscosity between theoretical and experimental values suggested the major role of particle aggregation and clustering

Numerical and experimental study of a jet impinging with axial symmetry with a set of heat exchanger tubes

The main purpose of this research is to predict the flow field of impinging turbulent jet with cylinder in a 3-d state. Nowadays, shear stress has multiple uses in the industry. The study has been conducted in both compressible and incompressible states with output velocities between 100 and 150 m/s, in different eccentricities of jet with respect to the first cylinder, and in various nozzle outlet orifice distances from front edge of the first cylinder. Pressure distribution and shear stress on cylinder surfaces have been determined and efficiency of jet in cleaning the heat exchangers pipes has been analyzed. Also, an experimental investigation has been conducted in order to verify the accuracy of the numerical results. Results show that if the distance between nozzle outlet orifice and the front edge of the first cylinder (L) equals 1.52 D (D is the diameter of the cylinder), the jet has the highest cleaning effect

Investigating the effect of adding silver nanoparticles to hybrid crystalline silicon solar cells

Hybrid silicon solar cells are an implementation of solar cells which have a simple fabrication process meanwhile absorbing a wider range of light spectrums compared to common silicon solar cells, although hybrid silicon solar cells have relatively low efficiencies. Metal nanoparticles have been known to enhance the performance of solar cells due to their localized surface plasmon resonance effect. The present study evaluates the addition of silver nanoparticles to enhance the properties and performance of hybrid silicon solar cells. In this regard silver nanoparticles are added to hybrid silicon solar cells producing different layer combinations in hybrid silicon solar cells. According to the results the addition of silver nanoparticles in specific combinations may enhance the performance whereas in other combinations may destroy the photovoltaic characteristics of the hybrid solar cell. A certain combination of the hybrid silicon solar cells including silver nanoparticles has been proposed wherein the properties of the cell are enhanced due to the plasmonic effect of silver nanoparticles. However, silver nanoparticles added on the surface of the photovoltaic cells cause shading, thus decreasing the active surface of the cell and thereby reducing the efficiency of the cells. Therefore, there is an optimum surface distribution for silver nanoparticles to benefit from the localized surface plasmon resonance effect meanwhile not shading a large amount of the cell and reducing the active surface area of the cell which is evaluated in the present research. Accordingly, by adding silver nanoparticles from a solution of 50% vl concentration the efficiency of the hybrid silicon cell reached 3.7% which is a significant increase compared to the efficiency of the ordinary hybrid silicon solar cells which was 1.8%

A Fuzzy-SOM Method for Fraud Detection in Power Distribution Networks with High Penetration of Roof-Top Grid-Connected PV

This study proposes a fuzzy self-organized neural networks (SOM) model for detecting fraud by domestic customers, the major cause of non-technical losses in power distribution networks. Using a bottom-up approach, normal behavior patterns of household loads with and without photovoltaic (PV) sources are determined as normal behavior. Customers suspected of energy theft are distinguished by calculating the anomaly index of each subscriber. The bottom-up method used is validated using measurement data of a real network. The performance of the algorithm in detecting fraud in old electromagnetic meters is evaluated and verified. Types of energy theft methods are introduced in smart meters. The proposed algorithm is tested and evaluated to detect fraud in smart meters also

PERFORMANCE EVALUATION OF LIQUID-COOLED PHOTOVOLTAIC SYSTEM USING NUMERICAL METHOD

The purpose of present study is establishing a simulation model to consider the performance of a water photovoltaic thermal system (PV/T) via the computational fluid dynamics method (CFD). The proposed model includes a water riser tube and an absorber plate to consider the conduction and convection heat transfer mechanisms. The simulation process was carried out in the ANSYS FLUENT software. The effects of two different parameters on the efficiency and performance of the system were investigated numerically. The performance of the PV/T system versus the changes in the absorbed radiation on the plate and the fluid inlet temperature were analyzed. The temperature distribution of different sections of the system was obtained. For validation of the presented method, a comparison study was carried out with the experimental results in the literature; satisfactory convergences were found between the measured data and the experimental results

GMDH algorithm for modeling the outlet temperatures of a solar chimney based on the ambient temperature

This work was carried out based on a constructed solar chimney with 2 m height and 3 m diameter. The temperature distributions were assessed based on the practical climatic conditions. In this work, the experimental data of temperature were investigated by a group method of data handling (GMDH). This method was applied as an artificial intelligence approach to predict the temperature changes, and also to find out the quality of the experimental data and temperature. In this case, a data set of 2000 condition-parameters for 30 days operation of solar chimney was applied. In order to obtain the network input and output variables, eight and four temperature sensors were set, respectively. In this study, according to the value correlation coefficient (R2) and the root-mean square error (RMSE), the results of the trained networks have been reported. In the modeling and calculations, the ambient temperatures have been considered. Also temperature prediction was carried out with high accuracy. Finally, the results showed that the solar chimney’s experimental data were qualified with no noise and some formulas were obtained for each output based on the temperature input variables

Solar radiation prediction based on ICA and HGAPSO for Kuhin City, Iran

In this study, sun radiation prediction has been carried out by utilization of ICA and HGAPSO algorithms, based on some climatic parameters such as air temperature, relative humidity and wind speed. Air temperature, relative humidity and wind speed data have been measured by accurate measuring tools in Kuhin city. The application of these data networks to predict solar radiation in a similar situation have been taught to the system. The networks precision is shown by their correlation coefficient (R2) and mean square error (MSE). Due to the different climatic conditions, solar radiation is very difficult to be predicted. Thus, the trained networks have deviations; hence the networks with R2 equal to 0.7 and above were acceptable. At the end, the solar radiation prediction was carried out for some the days of two years