Previous measurements of thermoacoustic heat transport across stacks of short plates, called thermoacoustic couples or TACs, revealed serious discrepancies between theory and experiment. The discrepancies are worst at higher drive ratios (the ratio of the peak acoustic pressure amplitude at a pressure antinode to the mean pressure of the gas), where prominent irregularities in the data series appear. In the previous work, the measurements were made with thermopiles having junctions that were located along the leading and trailing edges of the TAC plates. Because of its proximity to the edge, the thermopile may have been sensitive to effects which, though perhaps causing local deviations in the temperature profile, do not affect the temperature profile in interior regions of the plate. To investigate whether edge effects are the cause of any of these discrepancies, we have constructed a TAC with two thermopile, whose conjunction do not lie along the edge, and repeated some of the previous measurements. Measurements were also made with a stack of long plates to probe how far the irregularities extend in to the interior of the plate. It was found that the irregularities are not isolated to the edge of the TAC. The temperature profile of interior portions of the plates mimic that measured along the edge.

Subjects: Heat; Transmission; Temperature; Thermodynamics; Pressure; Sound pressure; Thermopiles; Heat pumps; Energy conversion; Energy storage.; Acoustics; Thermoacoustics; Thermoacoustic Heat Transport