Heat transfer enhancement in finned annulus of elliptic-circular heat exchanger

Abstract

In this numerical study, a trapezoidal finned elliptic-circular heat exchanger is investigated for thermal performance based on the various geometrical parameters. The inner core of this exchanger is circular and augmented with trapezoidal fins longitudinally, whereas the outer core is elliptic. For the first time, the trapezoidal fins are used in this specific duct configuration. The configuration of the proposed heat exchanger depends on the number of fins, fin height and ratio of the radius of the inner circle to the semi-minor axis of the ellipse The material of the inner circular core and trapezoidal fins is assumed to have infinite thermal conductivity. The constant heat flux condition is imposed on the inner pipe and trapezoidal fins, whereas the adiabatic condition is considered for the outer elliptical core of the heat exchanger. The simulation is performed using the finite volume method based on the software ANSYS Fluent. The friction factor (fRe) and Nusselt number (Nu) have been computed and plotted for various fin configurations. The results suggest that the performance of the heat exchanger can be effectively influenced by the number of fins, fin height and radius of the inner circular pipe. For practical interest, a larger number of trapezoidal fins with a higher height and are recommended.