Abstract
In this paper, after a short review of the heat exchangers (HEX) types and applications with different technologies was presented, a lot of parameters which mainly affect the thermal-hydraulic performance of heat exchangers have been offered to characterize the optimal design of HEX. It can be seen that the presence of a fin in a smooth channel or tube provides the best overall performance of HEX. Furthermore, the use of a vortex generator, which is considered prominent passive method, significantly increases the rate of heat transfer and reduces the pressure drop. Finally, the current review provides some recommendations for future studies to enhance the performance of HEX.