Numerical and experimental analyses were carried out to study the heat transfer and flow in the plate-fin and tube heat exchangers with inclined block shape vortex generators mounted behind the tubes. The effects of different span angles alpha (alpha = 30degrees, 45degrees and 60degrees) are investigated in detail for the Reynolds number ranging from 400 to 3000. Numerical simulation was performed by a 3D turbulence analysis of the heat transfer and fluid flow. Experiments were carried out by an infrared thermovision and a water tunnel system, respectively, to visualize the temperature distribution and local flow structure. The results indicated that the proposed heat transfer enhancement technique is able to generate longitudinal vortices and to improve the heat transfer performance in the wake regions. The case of alpha = 45degrees provides the best heat transfer augmentation. A reduction in fin area of 25% may be obtained if vortex generators embedded fins are used in place of plain fins at Re-Dh = 500. (C) 2004 Published by Elsevier Ltd.