The present study used $TiO_2$-nanofluid with different volume ratios as the working fluids of a thermosyphon and grooved heat pipe and investigated various parameters such as volume concentration of nanoparticles, orientation, heat flux, and cooling media. Further, the present study used nanofluids and dispersed $TiO_2$-nanoparticles into pure water with each cross-blended concentration of 0.05%, 0.1 %, 0.5%, and 1 %. The authors observed the best heat transfer performance in the 0.05% concentration with thermosyphon. The present study presents the enhancement of heat transfer performance with $TiO_2$-nanofluids, and fabricated a heat pipe from a straight stainless steel tube with an outer diameter and length of 10 and 500 mm, respectively. At the optimum condition for the pure refrigerant, the thermosyphon with 0.05% $TiO_2$-nanoparticle concentration gave 1.40 times higher efficiency than that of pure water.