The present paper deals with the longitudinal heat transportation by oscillatory flow in small grooved tubes. The heat transportation experiments were conducted for the grooved tubes fabricated by a 3D printer. The internal diameters of the contraction and expansion sections of the grooved tube were 2 and 4 mm, respectively. The lengths of the contraction and expansion sections were respectively 3.3 and 2.3 mm and the total length of the grooved tubes was around 165.7 mm. The frequency and stroke length of oscillatory flow were varied from 0.1 to 3.0 Hz and from 15 to 20 mm, respectively. As a result, the effective thermal diffusivity in a grooved tube reached a value 2.3 times greater than that of a straight tube when the frequency was higher than 0.5 Hz, whereas no significant effect was observed when the frequency was lower than 0.5 Hz.
