Current Issue : January - March Volume : 2013 Issue Number : 1 Articles : 6 Articles
This paper presents a MATLAB based user friendly software tool called as PV.MY for optimal sizing of photovoltaic (PV) systems.\r\nThe software has the capabilities of predicting the metrological variables such as solar energy, ambient temperature and wind speed\r\nusing artificial neural network (ANN), optimizes the PV module/ array tilt angle, optimizes the inverter size and calculate optimal\r\ncapacities of PV array, battery, wind turbine and diesel generator in hybrid PV systems. The ANN based model for metrological\r\nprediction uses four meteorological variables, namely, sun shine ratio, day number and location coordinates. As for PV system\r\nsizing, iterative methods are used for determining the optimal sizing of three types of PV systems, which are standalone PV\r\nsystem, hybrid PV/wind system and hybrid PV/diesel generator system. The loss of load probability (LLP) technique is used for\r\noptimization in which the energy sources capacities are the variables to be optimized considering very low LLP. As for determining\r\nthe optimal PV panels tilt angle and inverter size, the Liu and Jordan model for solar energy incident on a tilt surface is used in\r\noptimizing the monthly tilt angle, while a model for inverter efficiency curve is used in the optimization of inverter size....
Simulation-driven design with computational fluid dynamics has been used to evaluate the flow downstream of a hydropower\r\nplant with regards to upstream migrating fish. Field measurements with an Acoustic Doppler Current Profiler were performed, and\r\nthe measurements were used to validate the simulations. The measurements indicate a more unstable flow than the simulations,\r\nand the tailrace jet from the turbines is stronger in the simulations. A fishway entrance was included in the simulations, and the\r\nsubsequent attraction water was evaluated for two positions and two angles of the entrance at different turbine discharges. Results\r\nshow that both positions are viable and that a position where the flow from the fishway does not have to compete with the flow\r\nfrom the power plant will generate superior attraction water. Simulations were also performed for further downstream where the\r\nflow from the turbines meets the old river bed which is the current fish passage for upstream migrating fish. A modification of the\r\nold river bed was made in the model as one scenario to generate better attraction water. This considerably increases the attraction\r\nwater although it cannot compete with the flow from the tailrace tunnel....
The application of computational fluid dynamics (CFDs) in the area of porous media and adsorption cooling system is becoming\r\nmore practical due to the significant improvement in computer power. The results from previous studies have shown that CFD\r\ncan be useful tool for predicting the water vapour flow pattern, temperature, heat transfer and flow velocity and adsorption rate.\r\nThis paper investigates the effect of silica gel granular size on the water adsorption rate using computational fluid dynamics and\r\ngravimetric experimental (TGA) method....
We deal with an algorithm that, once origin and destination are fixed, individuates the route that permits to reach the destination\r\nin the shortest time, respecting an assigned maximal travel time, and with risks measure below a given threshold. A fluid dynamic\r\nmodel for road networks, according to initial car densities on roads and traffic coefficients at junctions, forecasts the future traffic\r\nevolution, giving dynamical weights to a constrained K shortest path algorithm. Simulations are performed on a case study to test\r\nthe efficiency of the proposed procedure....
The effects of Venturi structural parameters on its hydraulic performance were studied, which provided theoretical basis for the\r\ndesign of Venturi injector. With an inlet diameter of 50 mm, based on the method of computational fluid dynamics (CFD),\r\nthe effects of the structural parameters (such as throat taper, throat contraction ratio, and throat length) on their hydraulic\r\nperformance (such as outlet faceted average velocity, minimum pressure, and critical pressure) were studied under different inlet\r\npressures and pressure differences between inlet and outlet. A power function relationship existed between the mean velocity in\r\noutlet section and pressure difference, with an approximate flow stance index of 0.53. Minimum pressure occurred in the throat\r\ninlet wall and there was a linear relationship between the minimum pressure and the pressure difference at the inlet and outlet. The\r\nthroat contraction ratio was the main factor on the effect of Venturi injector performance, which was positively correlated with\r\noutlet velocity, negatively to critical pressure, the minimal in-tube pressure, coefficient of local head loss, and fertilizer absorption\r\nratio. For designing Venturi injector, contraction ratio should be reasonably selected according to the coefficient of local head loss\r\nand fertilizer absorption ratio....
Computational fluid dynamic techniques have been applied to the determination of drag on oceanographic devices (expendable\r\nbathythermographs). Such devices, which are used to monitor changes in ocean heat content, provide information that is\r\ndependent on their drag coefficient. Inaccuracies in drag calculations can impact the estimation of ocean heating associated with\r\nglobal warming. Traditionally, ocean-heating information was based on experimental correlations which related the depth of the\r\ndevice to the fall time. The relation of time-depth is provided by a fall-rate equation (FRE). It is known that FRE depths are\r\nreasonably accurate for ocean environments that match the experiments from which the correlations were developed. For other\r\nsituations, use of the FRE may lead to depth errors that preclude XBTs as accurate oceanographic devices. Here, a CFD approach\r\nhas been taken which provides drag coefficients that are used to predict depths independent of an FRE....
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