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A Magnetic Levitation Rooftop Turbine Ventilator: A Case Study for Wind Micro-Generation

Ponnson Kaewtip, Naebboon Hoonchareon

This case study develops a prototype of a magnetic levitation rooftop turbine ventilator (RTV) through redesigning a standard rooftop ventilator that is typically mounted upon rooftops of factories, constructed to wind microgeneration system. By re-arranging positions of the rotor and the stator and integrating the magnetic levitation system to assisting support weight of turbine body, which can result in a very low starting torque so as to minimize the selfstarting speed (m/s). Thus, it could easily turn and be able to rotate in low-speed wind ambient. This can practically improve responsiveness to intermittent wind and its directional change. The testing apparatus was conducted with wind speeds from 0-14.0 m/s, incremented by 0.2 m/s each iteration, where the test results show that the RTV self-starts at a wind speed of 0.4 m/s and minimal charged speed was recorded at 95.8 RPM at a voltage of 12.07 VDC (activated charging voltage via battery bank of two 12 V, 100 A—in parallel connection) at 7.8 m/s. Then, it reaches ceiling voltage of 35.3 VDC and 0.51 ADC at turning approximately 119 RPM in which it produces power output 18 watts. At cut-out speed of 14.0 m/s and also rated output speed, the RTV optimizes the turning at 160.6 RPM while generating 1.02 ADC, in which it produces a maximum power output of 36 watts. For the modes of finance; ROI remarks at 6.21, payback period at 4.03 years, and cost per kWh is as low as 2 cents/kWh, assuming operating at average speed of 14.0 m/s all year long.