i Na

sion hree d. A pil quid cin icle 2009 Elsevier Ltd. All rights reserved. in the itute an eat fro nents. t with hile pr tions have been conducted to study boiling and natural and forced convection using nanofluids [2]. Due to the useful features of a nanofluid, various research groups [3–14] have tried to engage it within a heat pipe and study the subsequent thermal enhancement experimentally. Different nanoparticles such as silver [3,8,11,13], CuO [5,9], diamond [6,12], titanium [4,7], nickel oxide [10], and gold [14] have been utilized within the heat pipe working fluid. The improved thermal Vafai [15] is modified to include the effects of nanofluids within a cylindrical heat pipe. A common range of concentration for differ-ent nanoparticles, namely Al2O3, CuO, and TiO2 in water is consid-ered as the operational fluid within the heat pipe under various heat inputs. The temperature profile, thermal resistance, and the maximum heat transfer limits are investigated. A significantly higher thermal performance is observed due to a reduction in the thermal resistance as well as the end to end temperature gradient. Furthermore, the maximum capillary limit heat transfer increases when using a nanofluid as the working fluid. To the best of our knowledge, there is no study on the effect of a nanofluid on th