In this research, the effect of nanofluids including graphite and water on the heat transfer enhancement in heat Exchangers with both straight and rotational inner tube were examined. Nano-fluids including graphite and water were obtained at 0.01, 0.02 and 0.03 %volume concentrations by means of pure water as a base fluid. The aim of the study is to experimentally investigate and compare the influence of straight inner tube on the performance of a double tube heat exchanger at different flow rates, different capacity ratios (0.25, 0.5, 0.75, 1), different rotation rates (0 RPM, 100 RPM, 150 RPM, 200 RPM, 300 RPM, 500 RPM and 750 RPM) and by using nanofluid including graphite and water volume at values of 0.01, 0.02, 0.03%. In the experiments the flow is turbulent. In order to determine the heat transfer enhancement, the experimental datas were compared for pure water and nano-fluids. According to the results, Nusselt number, pressure loss, efficiency of heat exchanger were gauge. By the results achieved from experiments, correlations for Nusselt number have been reproduce and experimental data have been compared with ones in the literature by drawing graphics. The experiment that provides the best increase in heat transfer is the nanofluid including 0.02% volume concentrations of graphene/water at 500RPM speed.