Figure of merit and improved performance of a hybrid thermomagnetic oscillator. (15th December 2019)

• Record Type: Journal Article
• Authors: Deepak, K.; Pattanaik, M.S.; Ramanujan, R.V.
• Is Part Of: Applied energy. Volume 256(2019)
• Publication Date: 2019-12-15
• Subjects: Thermomagnetic oscillator -- Figure of merit -- Energy harvesting -- Thermomagnetic cooling; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2019.113917
• Languages: English
• ISSNs: 0306-2619

Abstract

Graphical abstract: Highlights: Figure of merit analyzed for energy harvesting of a thermomagnetic oscillator. Evaluation of figure of merit for first and second order transition alloys. The alloy with best figure of merit used for comparison of spacer material. Better performance was obtained with flexible spacer compared to rigid spacer. Abstract: The figure of merit for energy harvesting of a thermomagnetic oscillator has been analyzed. For the first time, a figure of merit for a thermomagnetic device combining the material properties and device parameters has been established. Our analysis indicates that alloys with a sharp magnetic transition with respect to temperature and lower hysteresis exhibit higher figure of merit for a given set of heat load and heat sink temperatures. The material with the highest figure of merit, (MnNiSi)0.68 (Fe2 Ge)0.32, was employed to construct a thermomagnetic oscillator. A thermomagnetic alloy was coupled to a permanent magnet by a flexible spacer, one end of the flexible spacer was attached to the thermomagnetic alloy and the other to the permanent magnet. Use of a flexible spacer increases the oscillation frequency by 32% compared to a rigid spacer. The permanent magnet also exhibited damped oscillations, resulting in an increase voltage/cycle by 18% compared to the rigid spacer case. Thus, figure of merit is a suitable guideline for tuning the material properties and optimizing the device parameters for maximizing the performance of the thermomagnetic oscillator.