Experimental investigation of a novel standing-wave thermoacoustic engine based on PCHE and supercritical CO2

The pursuit of high amplitude and low onset temperature difference is one important topic in thermoacoustic engines. In this paper, a novel standing-wave thermoacoustic engine is constructed working with supercritical CO2, whose core components are integrated as a printed circuit heat exchanger (PCHE). Our experimental results confirm that at any location on the resonator, the pressure obeys a cosine law with time, and the whole pressure field exhibits a seesaw-like spatiotemporal behavior. Under a fixed charging mass, the amplitude of pressure oscillation increases with temperature difference, obeying a power law relation. The maximum amplitude achieved in this work is 0.419 MPa at a temperature difference of 151.0 degrees C and a mean pressure of 9.621 MPa. Besides, the frequency with an average of 7.6 Hz shows weak variations. The onset temperature difference decreases as the critical pressure is approached, and the minimum value achieved is 14.8 degrees C. Moreover, the cooling effect of oscillating CO2 to the high-temperature portion of the stack is revealed, causing the strongly nonlinear temperature profile along the stack. This paper manifests that supercritical CO2 and PCHE are highly prospective to be employed in thermoacoustic devices.