On November 23th 2010, the Score team and Aster successfully tested a wood fired thermoacoustic engine with integral alternator at City University London.
Aster in collaboration with Nottingham University developed and built a planar traveling wave 2-stage thermoacoustic engine. City University London designed and built the prototype wood stove, the two were successfully integrated and power was generated on the first run. Score also includes the University of Manchester, Queen Mary University of London and the charity Practical Action.
The aim of this test was to bring all together and to demonstrate;
- The simple construction based on the idea of a finned or corrugated back plate
- Ease of integrating the planar design with a stove
- Heat transfer by convection rather than by radiation between stove and regenerator
- The rapid increase of performance at increasing mean pressure
- Feedback by near traveling waves in order to end up with the smallest possible feedback loop.
When pressurized to 0.5 barg (150 kPa) the highest electric output measured at 350 °C regenerator temperature difference was 23 W using a standard loudspeaker as linear alternator. The measured acoustic to electric conversion efficiency of this speaker however is only 35%. A better alternator of 60% efficiency is under construction by the Nottingham University. When available, this alternator in the same configuration raise electric output to nearly 40 W. Steady state running achieved 7.5 Watts to charge a 12v Battery with atmospheric pressure acoustics.
For more information about Score see: www.score.uk.com