نشریه فناوری های نوین در سیستم های انرژی
سال یکم شماره 3 (پیاپی 103، پاییز 1394)

In this paper the nonlinear forced vibration of thin circular functionally graded plate resting on Winkler-Pasternak and nonlinear Winkler foundation is investigated. The governing equations of the system are constructed using the von-Karman geometric nonlinear theory. Plates with edges elastically restrained against rotation and inplane displacement are analyzed. In this study, it is assumed that the plate can be subjected to any periodic distributed lateral loading with respect to time. The Galerkin method is used to reduce the nonlinear partial differential equations to a nonlinearly second-order ordinary differential equation for the central deflection. The Homotopy Perturbation Method is employed to analysis the vibration of the circular plate which is subjected to the vibration amplitude of the same or bigger order of the plate thickness. The effects of various parameters including large vibration amplitude, elastic foundation parameters and volume fraction on frequency ratio and variation of radial and circumferential stresses are considered. Based on the results, with increasing the vibration amplitudes the frequency ratio is increased, consequently. On the other hand, the variation of frequency ratio versus volume fraction is reversely. According to the results, the first approximation of HPM leads to highly accurate solutions for geometrically nonlinear vibration of circular thin FGM plates. Additionally, volume fraction and vibration amplitude affect the frequency ratio significantly.

In the last two decades of the twentieth century, using of hydraulic micro turbines has been wide attention globally. Due to the global move towards decentralization of electric energy production, by using of micro hydropower plants, a comprehensive program for the development of micro turbines compatible with the geographical conditions of Iran was proposed. Hydrocoil is one of the selected turbines of this program. Hydrocoil is a portable axial turbine with low head and flow. In general, the Hydrocoil is designed and built inspired by Archimedes screw pump. Currently, only one manufacturer in the world produce Hydrocoil and Technical information related to it is exclusively at the discretion of this manufacturer. In this paper, in order to achieve the operating Characteristic of the turbine, constant blade pitch hydrocoil , has been studied numerically. Under similar conditions, this results were compared with the results obtained by the University of Pennsylvania. This comparison proves the accuracy of the results. Furthermore, this study was to determine and analyze the behavior of turbines in various conditions in order to achieve working characteristics, main characteristics and constant efficiency characteristics of hydrocoil. These results provide necessary background to build and optimization of hydrocoil.

The radiation Sun has a high power the amount of energy consumption is several thousand times and that for researchers to exploit the large amounts of energy in order to fulfill the increasing global consumption focused In this study, using data from the weather station Save radiation in a three-year period of 1393-1390 to find a suitable model to estimate the intensity to solar radiation reaching the surface of the statistics action is sunshine. The results obtained were analyzed for statistical charts. The solar data also examined at the nearest meteorological station.

Various problems due to presence of vapor water impurity in the natural gas flow have created dehumidification units in the natural gas refineries. In this article the effect of different operational parameters on the dynamic behavior of the adsorption bed and also consumed energy of desorption cycle of the Sarakhs' gas refinery dehumidification unit has been investigated via simulation using Aspen Adsim software. The obtained results indicated that increasing the inlet gas pressure as well as temperature and also molar flow decreasing will result in lower energy consumption for bed recovery and also higher capacity for the adsorption of water vapor.

One way to increase the heat transfer rate adding nanoparticles to the fluid and is making Nano fluids. Free convection heat transfer in cylindrical geometry, due to their widespread use in the chemical engineering industry and is of utmost importance. In this study free convection heat transfer by Non-Newtonian Nano fluids in a cylindrical chamber, using computational fluid dynamics were studied. For prepare the Nano fluids two types of nanoparticles Al2O3 and TiO2 was used. Effect of type and concentration of nanoparticles and also the aspect ratio cylindrical heat transfer rate were investigated. Independency of mesh operation was carried out by testing three different mesh and finally was selected the best mesh in terms of accuracy and computational time. The results of the simulations were compared with the results of empirical correlations valid. The results were in good agreement with experimental results. The results showed that low concentrations of nanoparticles significantly increase the heat transfer rate. But further increase the concentration of nanoparticles has a negative effect and decrease the transmission rate. In fact, in optimum concentrations of nanoparticles, the maximum heat transfers. The results show that the distribution of TiO2 nanoparticles is greater than the effect of Al2O3 distribution.