Abstract: | The longitudinal heat transfer in capillary pipes is enhanced by fluid oscillation. The analytical solution to this phenomenon was obtained considering the wall thermal conductivity. Based on this solution, the effects of wall conductivity and thickness were investigated for the case of large amplitude of fluid motion. The longitudinal heat transfer through the fluid part was more enhanced in highly conductive thick pipes. This is because the region where the heat is transferred backwards is smaller in these pipe sections. The direction of longitudinal heat transfer depends on the phase difference of temporary change between the velocity and temperature; it depends on whether or not the difference exceeds π/2. From this point of view, the most effective wall regarding this problem is presented, where the wall temperature does not change preserving the mean temperature of the location during the oscillation. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(2): 129–139, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10126 |