Several qualitative and quantitative methods to evaluate the performances of an ultrasonically assisted double tube heat exchanger are presented in this work. These methods are theoretically developed and applied to four different fluid-flow configurations: hot and cold fluid interchangeable positions, in parallel-flow (co-flow) or counter-flow and allow estimating heat exchanger outlet temperatures, energetic performances and heating transfer coefficients. Relevance of each method presented with respect to the selected configuration and to the required improvement is discussed. It appears that one method may be more suited than the others to analyze enhancement or thermal behavior induced by ultrasound.