Search Results (3)

In this paper, an axial flux electromagnetic energy harvester driven by a Stirling engine (AFEEH-SE) is presented for recovering waste heat above 200 °C. A gamma-type Stirling engine with a slider-crank drive mechanism serves as the power unit to convert thermal energy into rotational mechanical energy. The harvester comprises a rotating magnet array and a stationary coil array. Finite element simulations were conducted to analyze and compare the voltage output under different magnet and coil parameter configurations. Subsequently, a prototype utilizing mineral oil combustion as the heat source was designed, achieving a rotational speed of 950 rpm under open-circuit conditions. Through systematic adjustments to the magnet and coil parameters, the optimal performance configuration was determined to maximize the output power of the harvester. Under this optimized configuration, the AFEEH-SE achieved an effective power output of 57.13 mW, capable of charging a 2.2 mF capacitor to 28 V in 49 s. This study demonstrates the feasibility of the AFEEH-SE in practical applications and provides a solid foundation for the future field of waste heat recovery. Full article

Electromagnetic energy harvesters have been used to capture low-frequency vibration energy of large machines such as diesel generators. The structure of an electromagnetic energy harvester is either planar or tubular. Past research efforts focus on optimally designing each structure separately. An objective comparison between the two structures is necessary in order to decide which structure is advantageous. When comparing the structures, the design variations such as magnetization patterns and the use of yokes must also be considered. In this study, extensive comparisons are made covering all possible topologies of an electromagnetic energy harvester. A bench mark harvester is defined and the parameters that produce maximum output power are identified for each topology. It is found that the tubular harvesters generally produce larger output power than the planar counterparts. The largest output power is generated by the tubular harvester with a Halbach magnetization pattern (94.7 mW). The second best is the tubular harvester with axial magnetization pattern (79.1 mW) when moving yokes are inserted between permanent magnets for flux concentration. When cost is of primary concern, the tubular harvester with axial pattern may become a best option. Full article

This paper develops an electromagnetic energy harvester, which can generate small-scale electricity from non-directional water flow in oceans or rivers for remote sensors. The energy harvester integrates a Tesla disk turbine, a miniature axial-flux permanent magnet generator, and a ring cover with symmetrical grooves which are utilized to rectify flow direction. A compact structure is achieved by mounting the permanent magnets of the generator directly on the end surfaces of the turbine rotor. Theoretical analysis is implemented to illustrate the energy conversion process between flow kinetic form and electrical form. Additionally, a mathematical model is developed to investigate the magnetic field distribution produced by the cubical permanent magnets as well as parametric effect. Plastic prototypes with a diameter of 65 mm and a height of 46 mm are fabricated by using a 3D printing technique. The effect of the groove angle is experimentally investigated and compared under a no-load condition. The prototype with the optimal groove angle can operate at flow velocity down to 0.61 m/s and can induce peak-to-peak electromotive force of 2.64–11.92 V at flow velocity of 0.61–1.87 m/s. It can be observed from the results that the analytical and the measured curves are in good accordance. Loaded experiments show that the output electrical power is 23.1 mW at flow velocity of 1.87 m/s when the load resistance is approximately equal to the coil resistance. The advantages and disadvantages of the proposed energy harvester are presented through comparison with existing similar devices. Full article