Lumped Element Model for Thermomagnetic Generators Based on Magnetic SMA Films

Area of Science:

• Materials Science
• Energy Conversion
• Physics

Background:

• Thermomagnetic generators (TMGs) offer a pathway for energy harvesting.
• Magnetic shape memory alloy (MSMA) films exhibit unique thermomagnetic properties crucial for TMGs.
• Understanding the coupled dynamic properties of MSMA-based TMGs is essential for efficient energy generation.

Purpose of the Study:

• To develop and validate a lumped element model (LEM) for MSMA-based TMGs.
• To analyze the resonant self-actuation and power generation capabilities of these devices.
• To investigate potential applications in waste heat recovery, particularly near room temperature.

Main Methods:

• Development of a lumped element model (LEM) to simulate TMG dynamics.
• Experimental validation using a Ni-Mn-Ga MSMA film.
• Simulation of time-resolved temperature, magnetic field, and magnetization changes.
• Analysis of resonant self-actuation frequency and temperature variations.

Main Results:

• The LEM accurately describes the coupled dynamic properties of MSMA films in TMGs.
• A Ni-Mn-Ga film generated 3.1 µW (80 mW/cm³) at 443 K heat source temperature.
• Resonant self-actuation was observed at 114 Hz with rapid temperature changes (10 K in 1 ms).

Conclusions:

• The developed LEM is a valuable tool for studying and optimizing MSMA-based TMGs.
• The study demonstrates the feasibility of MSMA films for efficient thermomagnetic energy conversion.
• The LEM can guide future research towards waste heat recovery applications at lower temperatures.