The mixture of nanoparticles in a fluid can improve the h of the fluid. In this paper, the h of water, Al-water, Al2O3-water, Fe3O4-water and TiO2-water nanofluids with 0.04 volume fraction of nanoparticles have been analytically calculated for a shell and tube heat exchanger. Moreover, the energy effectiveness and environmental effects have also been calculated for the above nanofluids. It is found that, the h of the above nanofluids were approximately 17, 14, 13, and 10% higher compared to pure water, respectively. Furthermore, energy effectiveness also improved by 31, 35, 41, and 37%, respectively. If all sectors could use nanofluids in their heat exchanger systems, then significant amounts of heat emission could be reduced all over the world. Therefore, nanofluid can be used as a coolant to improve the performance of the heat exchanger system.