Thermodynamic optimization in laminar and fully developed flow in double pipe heat exchanger with arrow-shaped extended surfaces: A novel design

Abstract

An innovative design of extended fins in the form of arrow fins is optimized for high performance heat transfer in a double pipe heat exchanger (DPHX). The arrow fins are designed within the trapezoidal fin to save material, weight, cost and making energy-efficient DPH. The arrow fins are investigated for the first time in DPHX. The FEM approach is used for computational simulation of the present work. A thermal boundary condition of constant heat flux is imposed on the arrow fins and inner pipe assembly. The results are computed in terms of fRe, Nusselt number and j-factor. The results dictate that the geometrical configurations of arrow DPHX for a significant rise in the values of the Nusselt number are: 80 % height of arrow fins is recommended when the number of arrow fins varies from 6 to 24, 20 % height for 30 arrow fins in the case of smaller values of radii ratio (Rˆ). For larger values of Rˆ, 20 % height of arrow fins may be selected for M=6&30, while for arrow fins varying from 12 to 24, H*=0.8 is recommended. On comparison of the thermal performance of the arrow-finned DPHX with the trapezoidal-finned DPHX, the maximum rise of the Nusselt number and j-factor are 113.2 % and 124.2 %, respectively. The proposed design of arrow-finned DPHX has advantages over the design of trapezoidal finned DPHX due to the significant decrease both in manufacturing cost and weight, increased thermal performance, and saving energy.

Keywords

• Heat transfer enhancement
• FEM
• Double pipe heat exchanger
• Longitudinally extended fins
• Arrow-shaped fins