On the way to 50W electric output

Thermoacoustic electricity generation is still under development. The emphasis hereto is on  increasing power level and efficiency and in reducing the cost per Watt electric output power.

Early May, Aster together with the Nottingham Score team managed to get the demo2.2 Score thermoacoustic engine to produce 36 Watts electricity continuously, and 45 Watts peak. The working gas was air at an absolute pressure of nearly 200 kPa. A high power speaker was used as alternator. Its acoustic to electricity conversion efficiency is about 50% which means that the engine delivers 70-90 Watt net acoustic output power. Increasing the mean pressure up to 250 kPa and/or using a more efficient alternator will suffice to achieve the 50 Watt project target.

This result was obtained by modifying the acoustic circuitry toward a serial connection of two individual (acoustic) matched engine stages. This yield both a higher power density and a reduction of feedback tube length. The test set-up is shown below.

Score rig May7

The current (messy) shape of the tubing is for measuring purposes and for easy access. In a final version the tubing can be folded to fit into, or be part of, the wall of the stove.  Note the relatively short feedback tube length which allows for a higher frequency and proportionally higher electric output of the alternator.

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