Nanofluid is a new engineering fluid which could improve the performance of heat exchanger. The aim of this paper is to study the effect of different particle shapes (cylindrical, bricks, blades, and platelets) on the overall heat transfer coefficient, heat transfer rate and entropy generation of shell and tube heat exchanger with different baffle angles and segmental baffle. Established correlations were used to determine the abovementioned parameters of the heat exchanger by using nanofluids. Cylindrical shape nanoparticles showed best performance in respect to overall heat transfer coefficient and heat transfer rate among the other shapes for different baffle angles along with segmental baffle. An enhancement of overall heat transfer coefficient for cylindrical shape particles with 20 baffle angle is found 12%, 19.9%, 28.23% and 17.85% higher than 30 degrees, 40 degrees, 50 degrees baffle angles and segmental baffle, respectively in corresponding to 1 vol.% concentration of Boehmite alumina (gamma-AlOOH). Heat transfer rate is also found higher for cylindrical shape at 20 baffle angle than other baffle angles as well as segmental baffle. However, entropy generation decreases with the increase of volume concentration for all baffle angles and segmental baffle. (C) 2013 Elsevier Ltd. All rights reserved.