Asymmetrically heated multi-stage travelling-wave thermoacoustic electricity generator

Recent developments of thermoacoustic engines have demonstrated that thermoacoustic technology is a viable option for waste heat recovery and low-cost electricity generation, Thermoacoustic technology is capable of converting low-grade heat to electrical power with only one moving part. Great reliance has been placed on evenly heated cores of multistage thermoacoustic engines, whatever the acoustic impedance is within the engine's core. This article proves that the unbalanced acoustic impedance within the cores can be effectively matched by using the asymmetric heat method. Accordingly, the thermoacoustic efficiency can be increased. DeltaEC code was employed to perform the numerical calculations and laboratory measurements were then taken to confirm the concept and validate the numerical model. Both numerical and experimental data show an increase in loop acoustic power with this new technique. DeltaEC simulation predicted an increase in the electrical power output from 24.4 W to 31.4 W, when heat supplied into the system went from (50%:50%) to a 40%:60% ratio, which matched an increase from 16.5 to 23 W in the experiments with no other change in the design except asymmetric heat input. DeltaEC results have implied that there is an optimal ratio of 30%:70%. It was also seen in the DeltaEC that the overall onset temperature decreased by about 40 °C for larger asymmetrical ratios of heat input, which is advantageous for this application.