Savonius wind turbines are a type of vertical axis wind turbine. In this research, the effect of some design parameters such as blade type, overlap ratio, separation distance, and blade thickness on the aerodynamic performance of a two-bladed Savonius wind turbine with the rotor diameter of 0,3 m was investigated numerically by using a realizable k-epsilon turbulence model. Three different levels were selected for each parameter. Computational fluid dynamics analyses were performed using Fluent software and the Taguchi method was used for the optimization process. It was seen that a Savonius rotor with an elliptical blade that has a 2 mm thickness, a 0,15 overlap ratio, and a 7,5 mm separation distance shows the best aerodynamic performance. The difference between the aerodynamic performances of the base and the optimized rotor was found to be greater at higher tip speed ratios than at lower tip speed ratios. The power coefficient was raised by nearly 17,9% for a tip speed ratio = 0,8. The optimal tip speed ratio value was changed from 0,8 to 1,0, after the optimization process.

In this study, radius-dependent solidity effect to the aerodynamic characteristic of a three bladed H-rotor Darrieus wind turbine consisting of NACA 0021 profile blades was investigated numerically in Ansys Fluent 14.1 software. After achieving independence from the mesh, the numerical method was validated with the experimental data and then numerical analyses were performed for different solidity values. Results show that the higher efficiency can be obtained both in low Type Speed Ratio (TSR) values with the increase of solidity and in high TSR values with the decrease in solidity. Power coefficient (Cp) has been enhanced as 4.25% with 0.75 m (M1) and Cp has been reduced as 0.57% with 1.25 m (M3) rotor radius according to 1 m rotor radius (M2), respectively.

One of the main issues that has limited the use of hydrogen as an energy vector for a long time is its low energy density per unit of volume. Alternative chemical storage methods have been developed in recent years to overcome the limitations associated with compressed or liquified hydrogen storage. One of these is the Liquid Organic Hydrogen Carrier (LOHC), which utilizes organic hydrocarbons that can capture hydrogen (through an exothermic hydrogenation reaction) and release hydrogen (through an endothermic dehydrogenation reaction). In this paper, a 0D model of an internal combustion engine fueled with a mixture of hydrogen and methane was used to investigate whether the enthalpy of the exhaust gases can balance the heat rate required to self-sustain the dehydrogenation stage. Two LOHC+ compounds were considered, namely, Perhydro-dibenzyltoluene and Perhydro-N-Ethylcarbazole. Four different hydrogen-to-methane ratios were considered, assuming an engine maximum brake power ranging from 500 to 6000 RPM. An energy balance was performed, balancing the dehydrogenation heat rate and the exhaust gas cooling heat rate, in order to establish the minimum temperatures of the exhaust gases required to self-sustain the LOHC+ dehydrogenation. We demonstrated that the minimum exhaust temperatures required to self-sustain the process in different running regimes and at different hydrogen-to-methane ratios are lower than literature and experimental exhaust temperatures.