Numerical investigations on a portable outdoor waste heat-driven standing-wave thermoacoustic engine

The present study focuses on developing a portable outdoor waste heat-driven thermoacoustic engine (TAE) with the capability to harness waste heat from commonly used camping gas stoves, enabling energy storage and acoustic power generation. To conserve space while enhancing heat-driven acoustic power output, the developed thermoacoustic system is composed of two quarter-wavelength standing-wave TAEs sharing a common closed end, forming a U-shaped configuration with two stacks symmetrically distributed on both sides. The numerical study simulates the combustion of an outdoor gas stove (primarily fueled by liquefied butane) to derive its temperature function. This function is then applied to the two-dimensional full-scale U-shaped TAE to yield self-excited thermoacoustic oscillations. To improve energy efficiency and acoustic power output, the study investigates the impact of the (1) temperature function generated by combustion, (2) working gas/medium, and (3) operating pressure. Additionally, nonlinear phenomena within the system are explored. The generated acoustic power can be further converted into electricity using piezoelectric elements or electric generators, serving as an emergency power source for mobile phone charging, car engine ignition, and emergency lighting. This research unveils significant potential for utilizing low-grade thermal energy to pioneer innovative outdoor thermoacoustic power sources.