The present paper deals with numerical simulation and triple-objective optimization of a double-tube heat exchanger equipped with an elliptic cross section in the presence of TiO2 nanofluid. A CFD simulation is done to find the thermal, fluid flow, and entropy generation behavior of suggested heat exchanger configuration. The results indicate that the change of geometrical and operational parameters has different influences on the suggested heat exchanger performance. Findings show that increasing the Reynolds number from 10,000 to 50,000 with TiO2 concentration of 0.3% results in increasing overall heat transfer coefficient from 9445.8 to 14,622 W m-2 K-1 for the spiral diameter of 220 mm. The results of specific entropy generation infer that in the Reynolds number of 4000 with changing TiO2 particle concentration from 0 (pure water) to 0.3%, the specific entropy generation increases from 0.97 to 1.209 kJ kg-1 K-1. A triple-objective optimization with overall heat transfer, friction factor, and specific entropy generation as objective functions, and nanoparticle concentration, Reynolds number, and spiral diameter as decision variables, is done. Different states regarding three objectives introduces as optimum studied system.
