This study investigated the flow characteristics around a cross-flow wind turbine. A wind tunnel experiment (WTE) was performed to measure the flow characteristics past the wind turbine when operating at the optimal t...This study investigated the flow characteristics around a cross-flow wind turbine. A wind tunnel experiment (WTE) was performed to measure the flow characteristics past the wind turbine when operating at the optimal tip-speed ratio of λ = 0.4. In addition, computational fluid dynamics (CFD) simulations were performed for the flow field around the wind turbine that was operating at tip-speed ratios of λ = 0.1, 0.4, and 0.7. The CFD approach was validated against the WTE measurements. CFD results confirmed that with an increase in λ, the velocity deficit was generally increased in the leeward of the return side of the wind turbine, while it was generally decreased in the leeward of the drive side of the wind turbine. It was also confirmed that with an increase in λ, the turbulence kinetic energy was generally increased in the leeward of the return side of the wind turbine, while it generally decreased in the leeward of the drive side of the wind turbine.展开更多
Amorphous silicon photovoltaic/thermal(a-Si-PV/T)technology is promising due to the low power temperature coefficient,thin-film property,thermal annealing effect of the solar cells,and high conversion efficiency in su...Amorphous silicon photovoltaic/thermal(a-Si-PV/T)technology is promising due to the low power temperature coefficient,thin-film property,thermal annealing effect of the solar cells,and high conversion efficiency in summer.The design of a-Si-PV/T system is influenced by a number of thermodynamic,structural,and external parameters.Parametric analysis is useful for a good design of the system.A dynamic distributed parameter model is built and verified in this paper.Outdoor tests are carried out.The impacts of operating temperature,mass flow rate,cover ratio of solar cells,heat transfer area,and frame shadow ratio on its performance are theoretically and experimentally investigated.The results indicate that seven or eight copper tubes are suitable to achieve a high overall efficiency of the a-Si-PV/T system.The frame and tilt angle shall avoid a shadow ratio of more than 8.3%during operation.The difference between power outputs at operating temperatures of 35℃and55℃in the first month is about 0.21%while it drops to less than 0.1%in the twelfth month.Compared with conventional PVT systems,the a-Si-PV/T system benefits from a higher design temperature with a minor efficiency decrement.展开更多
文摘This study investigated the flow characteristics around a cross-flow wind turbine. A wind tunnel experiment (WTE) was performed to measure the flow characteristics past the wind turbine when operating at the optimal tip-speed ratio of λ = 0.4. In addition, computational fluid dynamics (CFD) simulations were performed for the flow field around the wind turbine that was operating at tip-speed ratios of λ = 0.1, 0.4, and 0.7. The CFD approach was validated against the WTE measurements. CFD results confirmed that with an increase in λ, the velocity deficit was generally increased in the leeward of the return side of the wind turbine, while it was generally decreased in the leeward of the drive side of the wind turbine. It was also confirmed that with an increase in λ, the turbulence kinetic energy was generally increased in the leeward of the return side of the wind turbine, while it generally decreased in the leeward of the drive side of the wind turbine.
基金sponsored by China Postdoctoral Science Foundation(2022M713463)National Natural Science Foundation of China(52206292)+1 种基金the EU Marie Curie International Incoming Fellowships Program(703746)the Major Program of the Natural Science Foundation of Shandong Province(No.ZR2019ZD11)。
文摘Amorphous silicon photovoltaic/thermal(a-Si-PV/T)technology is promising due to the low power temperature coefficient,thin-film property,thermal annealing effect of the solar cells,and high conversion efficiency in summer.The design of a-Si-PV/T system is influenced by a number of thermodynamic,structural,and external parameters.Parametric analysis is useful for a good design of the system.A dynamic distributed parameter model is built and verified in this paper.Outdoor tests are carried out.The impacts of operating temperature,mass flow rate,cover ratio of solar cells,heat transfer area,and frame shadow ratio on its performance are theoretically and experimentally investigated.The results indicate that seven or eight copper tubes are suitable to achieve a high overall efficiency of the a-Si-PV/T system.The frame and tilt angle shall avoid a shadow ratio of more than 8.3%during operation.The difference between power outputs at operating temperatures of 35℃and55℃in the first month is about 0.21%while it drops to less than 0.1%in the twelfth month.Compared with conventional PVT systems,the a-Si-PV/T system benefits from a higher design temperature with a minor efficiency decrement.
