Abstract
This paper is described on the fundamental performance of the disc type thermomagnetic engine. The disc type engine has been designed in order to decrease the eddy current braking loss. The performance characteristics such as power, torque and loss has been measured, and compared with that of the cylindrical engine in the condition of the same volume of the temperature sensitive magnetic material. The eddy current braking loss is 0.04W which corresponds to 1/30 the loss in the cylindrical engine at the rotation speed of 0.4rps with the maximum power output. The total loss including partial losses due to the friction, the hydraulic effect and the eddy current braking is 0.9W in the disc type engine and is 1.8W in the cylindrical engine. The total loss in the disc type engine is reduced to be 50% of the value of the total loss in the cylindrical engine at the same condition mentioned above. The maximum output power is 6.0W at the rotation speed of 0.4rps in the disc type engine which is about 1.6 times larger than that of the cylindrical engine. The eddy current braking loss in the disc type engine is 0.7% of the value of the maximum output power, which is negligible effect in this engine. The power per unit volume of disc has the maximum value at the disc width of 40mm. The clearance between discs is decided to be of 1mm due to keeping the working fluid flow condition at a constant. The rotor thickness includes with the clearance and the disc thickness. The power per unit rotor thickness also has the maximum value at the disc thickness of 0.5mm. The thermomagnetic engine with the optimum condition can be designed by using these results. When the permanent magnet fixes the size constant, the disc type engine generates high output power in comparison with the cylindrical engine at the point of effective use of magnetic field.
