Investigating the potential impact of nanofluids on the performance of condensers and evaporators - A general approach

In this paper, the impact of nanofluids, when used as heat transfer fluids, on heat exchangers effectiveness is examined. The method used for the analysis is a modified ε-NTU. As it is already known from literature, any heat exchanger exhibits minimum and maximum values of effectiveness when the ratio of heat capacities Cr is one and zero, respectively. In this work, the improvement of effectiveness due to nanoparticles presence is investigated in heat exchangers in which Cr is zero (evaporators and condensers). The conducted analysis is performed for both laminar and turbulent flow conditions and it adopts specific assumptions so as the extracted results and conclusions to be generalized for most of the commonly used nanoparticles. Moreover, the effect of specific capacity drop and pressure drop as nanoparticles volume concentrations increase is explored. Finally, the potential benefit of nanofluids on minimizing heat exchangers size is investigated.