08. Sustainable & Renewable Energy

This research studies a float-type linear alternator driven by a thermoacoustic Stirling engine for examining the conversion among heat power, acoustic power, and electric power. In contrast to the mechanical type of external combustion engines, the thermoacoustic Stirling engine replaces mechanical solid pistons with sound waves for outputting mechanical power. By utilizing oscillating liquid columns as a load, the engine can operate without mechanical moving parts, thereby maintaining its simplicity. In this study, a permanent magnet is installed in a float within the liquid column and a solenoid coil surrounded outside the liquid column, forming the float-type linear alternator. To test its energy conversion performance, we conducted experiments with the engine under various liquid column volumes and numbers of permanent magnets. The former aims to change the acoustics impedance, and the latter aims to change the magnetic flux density. Significantly, the validation with a linear theoretical model confirms that enhancing magnetic flux density and acoustic impedance can improve conversion between heat power, acoustic power, and electric power. Therefore, the linear theoretical model is considered a guideline for designing a high-efficiency thermoacoustic Stirling generator with the float-type linear alternator.