Tidal power generation is viewed as a leading green energy approach. It is expected that the use of tidal power generation will become a primary method for local-supply-and-local-consumption energy, similar to photovoltaics and wind power. Because the current produced by tides changes with a definite periodicity, it is straightforward to forecast the production of electricity by tidal power generation. However, to cover the supply-and-demand differences in electric power, an accumulation-of-electricity system or a controllable electric power source is required. Hence, in this paper, the cost and electric power quality of an interconnection system constructed with a solid oxide type fuel cell (SOFC), photovoltaics (PV), and tidal power generators are investigated. By accessing the high-speed tidal current in the lake inlets of the Saroma Lake in Hokkaido, the demand of electric power and heat in a surrounding area are provided by the proposed system. As a result of the estimations of numerical analyses, the facility planning, costs, and electric power quality of the proposed system are identified, and the amount of time required to recover the cost versus the present energy cost is expected to be approximately ten years.
A prediction system with a one-region model was developed to predict water temperature in a spent fuel pit (SFP) after the shutdown of its cooling systems based on three-dimensional (3D) thermal hydraulic behavior calculated by using the CFD software, FLUENT 6.3.26. The system was extended to calculate the water level in the SFP during loss of all AC power supplies. In the prediction system, decay heat calculated by using the burn-up calculation software, ORIGEN 2.2, and the previously proposed correlation for evaporation heat fluxes from the water surface to air were used. Predicted results were compared with 3D calculations and measured temperatures for the shutdown of cooling systems and with the water temperature and level measured in SFPs at the Fukushima Daiichi Nuclear Power Station for loss of all AC power supplies. As a result, the predicted temperatures were found to agree well with the 3D calculations and it was confirmed that ORIGEN 2.2 well predicted decay heat for fuel assemblies with large decay heat which had been taken relatively recently from the shutdown reactor core. However, it was shown that decay heat predicted by ORIGEN 2.2 was overestimated for longtime cooled fuel assemblies with small decay heat and the previously proposed evaporation heat flux correlation overestimated the water temperature in the SFP, too.
Horizontal axis wind turbines can experience significant time varying aerodynamic loads, potentially causing adverse effects on structures, mechanical components, and power production. As designers attempt lighter and more flexible wind energy machines, greater accuracy and robustness will become even more critical in future aerodynamics models. Aerodynamics modeling advances, in turn, will rely on more thorough comprehension of the three dimensional, unsteady, vortical flows that dominate wind turbine blade aerodynamics under high load conditions. These variations may express the incidence angle and wind velocity changes over a 2-D S809 airfoil with the surface roughness effect. To numerically characterize these flows, the instantaneous speed and wind direction variations, represented by a peak function were used to characterize dynamic stall vortex kinematics and normal force amplification. For lack of experimental data in the pulsating motion case, the present numerical approach has been validated by comparing our results with an oscillating S809 airfoil experimental data. The results show the importance of taking into account the behaviour of the unsteady flow subject to abrupt variation of wind direction and velocity. As well as the influence of the surface roughness in the modelling of wind turbine flow. These results give an accurate estimation of aerodynamic loads which will subsequently improve the design of wind turbines.
The authors develop a small and simple steam-reforming reactor in a home-use size for n-dodecane as a heavy-hydrocarbons fuel. Under such a well-controlled condition by a thermal diffuser as the reactor satisfies two target-temperature criteria, the authors measure the inside-temperature profile and the hydrogen molar fraction (concentration) CH2, together with the molar fractions CCH4, CCO and CCO2 of other main gass components such as CH4, CO and CO2, respectively, using a gas chromatograph. In addition, the authors conduct theoretical calculations based on the thermal-equilibrium theory, and reveal CH2, CCH4, CCO and CCO2, as well as experiments. As a result, the authors successfully achieve suitable inside-temperature profiles. The steam-reforming reaction becomes more active at the position where temperature T > 800 K. The effects of the steam-to-carbon molar ratio S/C upon CH2, CCH4, CCO and CCO2 are shown, experimentally and theoretically. The experimental results agree well with the theoretical ones. Besides, carbon balance and conversion ratio show high accuracy in experiments.