Simple heat-conduction and thermoacoustic self-sustained oscillation branches are discussed employing current thermodynamics and thermoacoustic theory. Supposing a short regenerator where the local entropy production rate is homogeneous, thermodynamic stability is discussed analytically. Minimizing the entropy production rate of the short regenerator gives both simple heat conduction and the thermoacoustic self-sustained branches for a given oscillation mode. Necessary conditions for maintaining the thermoacoustic self-sustained branch restrict the oscillation mode. The conditions required for attaining stable oscillation in the short regenerator are also discussed.
