Clarification of Some Important Issues in Basic Thermoacoustic Theory

The past two decades have seen great development in thermoacoustic heat engines from standing wave thermoacoustic refrigerators to traveling wave thermoacoustic engines, from small scale thermoacoustically driven pulse tube coolers to large scale gas liquefiers, etc. In the meantime, thermoacoustic theory has also improved, which may be used to generalize the working principles in all oscillating flow heat engines. While thermoacoustic theory has been proved to be very useful in analyzing and modeling thermoacoustic heat engines, there are still some important basic points which are misleading or ambiguous and easily cause confusion. This article clarifies these issues by discussing enthalpy flow, entropy flow, work flow and Gedeon DC flow loss. The clarification is important because it helps one to understand the thermodynamics in thermoacoustic systems and to correctly simulate the system performance, especially when the thermoacoustic theory is extended into a non‐linear field considering gas non‐linearity, high order thermoacoustic terms, etc.