Abstract: The demand for energy has risen so much over the years because of the exponential increase in population and urbanization. Thus there is an immediate need for improving the efficiency of the heat transfer devices used in power generation. However, a major challenge to increasing the capacity of power plants is the accompanied increment in pressure drop which has to be balanced economically by the heat transfer efficiency. From ongoing studies, it was found that the heat transfer characteristics and thus the efficiency of heat exchangers can be greatly improved by using nanofluids. This paper explores previous studies on the enhancement of thermal conductivity of heat exchangers using nanofluids in them. The purpose of the paper is to prepare a review of the most recent innovations in heat exchangers using nanofluids as their working medium. It was concluded that in the majority of the situations, the use of nanofluids improves the rate of heat transfer. This in turn reduces the size of heat exchangers and saves energy, cost, reduces water usage and waste.