Effect of Gedeon streaming on thermal efficiency of a travelling-wave thermoacoustic engine

•The enthalpy flow carried by Gedeon streaming interacts with the local temperature.•Mechanism beneath the effect of Gedeon streaming on thermal efficiency is revealed.•Gedeon streaming changes the energy flow rates related to entropy transportation.•The unique temperature profile is the key essence. Gedeon streaming can lead to a drastic decrease in thermal efficiency of a travelling-wave thermoacoustic engine with looped configuration, which is conventionally attributed to the thermal loss carried by the streaming. This paper addresses the interdependence between the enthalpy flow carried by Gedeon streaming and the local temperature. Taking the newly developed four-stage travelling-wave thermoacoustic engine as an example, the simulations for various amounts of Gedeon streaming have been conducted to analyze the interaction between the enthalpy flow rate delivered by Gedeon streaming and the local temperature inside the regenerator and the thermal buffer tube. The characteristics of acoustic field, the impact of Gedeon streaming on the temperature profiles, the generated acoustic power and also the required input of heating power are presented and discussed in detail. The results indicate that the varying temperature profiles inside the regenerator and the thermal buffer tube, caused by the various amounts of Gedeon streaming, can substantially change certain energy flow rates, i.e., equivalent acoustic power and equivalent conduction heat flow rate due to the entropy transportation. This is the essential mechanism for Gedeon streaming affecting the thermal efficiency, instead of the enthalpy flow itself carried by the Gedeon streaming as the thermal loss.