Technological development has leads to need of more compact thermal management system especially in electronic cooling systems. Heat pipe with the use of mono and hybrid nanofluids are recent trends to satisfy the need of enhanced heat transfer and miniaturization in size. In this article, a state-of-the-art review on different types of heat pipe s, nanofluids preparation and characterization techniques have been carried out. The study begins with an overview of heat pipe and discussed about heat pipe with sintered, grooved and mesh wick structures, applications, mono nanofluids and hybrid nanofluids. The research works carried out for last decade are analyzed in terms of types of heat pipe, working medium, nanofluids preparation and characterization techniques. Effect of operating variables like nanoparticle size, shape and concentration, filling ratio, inclination angle and heat load are also presented. In last, the possible future research thrusts are presented.
Keywords: Mechanical engineering; Nanotechnology.