Start-up considerations for a small vertical-axis wind turbine for direct wind-to-heat applications

•Self-starting capability of a direct wind-to-heat VAWT system is predicted•Aerodynamic-induced torque is calculated from transient experimental data•Thermal generator impeller is analyzed with respect to start-up potential•Parametric study is conducted for thermal generator design parameters•Signif...

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Bibliographic Details
Published in:Energy conversion and management 2022-06, Vol.261, p.115595, Article 115595
Main Authors: McLean, D., Pope, K., Duan, X.
Format: Article
Language:English
Subjects:
Agitation
Darrieus
Data points
Heat generator
Impellers
Renewable heat
Rotating shafts
Rotation
Start-up
Systems design
Torque
Turbines
Vertical axis wind turbines
Vertical-axis wind turbine
Water heating
Wind power
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Summary:•Self-starting capability of a direct wind-to-heat VAWT system is predicted•Aerodynamic-induced torque is calculated from transient experimental data•Thermal generator impeller is analyzed with respect to start-up potential•Parametric study is conducted for thermal generator design parameters•Significant temperature rise is predicted for a properly-sized fluid volume Renewable production of space and water heating is needed for a sustainable society. The rotating shaft of a vertical-axis wind turbine can be equipped with a paddle wheel-style mixing impeller to directly heat a fluid by agitating or stirring the fluid. A Darrieus vertical-axis wind turbine, operating at or near its nameplate power capacity, is able to perform this function reliably as it is producing significant amounts of power; however, an autonomous wind-to-thermal system presents a challenge due to the difficulties associated with the start-up process of this type of turbine. The start-up difficulty is quantified herein by using a set of well-referenced vertical-axis wind turbine start-up data to derive the turbine’s torque and power values for each rotational velocity data point. It is shown that the turbine produces minimal positive torque during an extended region of operation around tip-speed ratio λ=1. A fluid-agitation thermal generator is considered by employing fluid mixing theory to compute the torque of a conceptual mixing impeller for different impeller diameters and styles. A thermal generator impeller is sized based on the derived experimental values and operational characteristics of the vertical-axis wind turbine data set. Thermodynamic analysis for the conceptual fluid-agitation generator shows that for an enclosed fluid volume ▪ = 1L, a fluid temperature rise of approximately ΔT=5°C can be achieved during one hour of system operation. The results demonstrate the potential of H-Darrieus turbines as renewable heat generating devices, while highlighting the need for careful system design to achieve successful start-up.
ISSN:0196-8904
1879-2227
DOI:10.1016/j.enconman.2022.115595