The dynamics of wind turbine has to be studied carefully to avoid unpredictable outputs and to make sure that consistent and efficient power is supplied according to the load requirements. There is a great and urgent necessity to increase the efforts in the development of the researches of the renewable energy to decrease the dependency on the conventional ones. The objective of this research is to make a contribution to the ongoing wind turbine research in the area of modeling, which is the first step required for the control and implementation of wind turbines. The wind turbine transfer function is derived and its performance has been established using the MATHLAB Software. This research provided a different approach to wind turbine modeling methodology. The results of this research may be used in another step for completing the control process of the wind turbine.
In this study, a numerical investigation on the thermo-hydraulic performance of thedouble pipe heat exchanger into heat transfer by different shapes of fins on the outersurface for the inner tube as extended surfaces. The inner and outer diameters of theinner pipe were (16.05 mm), (19.05 mm) respectively, and (34.1 mm), (38.1 mm) for theouter tube. The length of the heat exchanger was (1000 mm). Hot and cold water wereused as the working fluid, where the hot water flows inside of the inner one in counterflow with the cold water which flows in the annulus. The inlet temperature for the hotwater is (75 OC) while it is (30 OC) for the cold. The hot fluid flows at constant ratewhich is (0.1kg/s) while the cold is varied from (0.1 kg/s to 0.2 kg/s).The study wasperform using the known commercial CFD package (ANSYS – FLUNET 15) .Theresults shows that both (rectangular and triangular) fins enhances the heat transfercoefficient compare with the conventional plain tube .The rectangular fins presents anheat transfer enhancement ratio of (61% to 74%). Using of extended surfaces present agood result in saving energy by enhancing the performance of the double pipe heatexchangers used in petroleum industry.