A COMPREHENSIVE CHARACTERISTICS ANALYSIS OF FLUCTUATING CAM-SHAPED FIN AND TUBE HEAT EXCHANGER USING COMPUTATIONAL FLUID DYNAMIC

Abstract

Heat exchangers have admitted as prevalent devices with different practical applications in energy systems. Several approaches were used to enhance the efficiency of heat exchangers. In this study, a 3D CFD analysis of the oscillation of tube banks in a fin and tube heat exchanger is analyzed comprehensively to examine the effect of tube fluctuation on the heat exchanger’s efficiency. Thus, the hydro-thermal efficiency of the cam-shaped fluctuating tube bank with two different oscillation amplitudes (10°,20°) is investigated for the Re number of 13000. As a complementary analysis, exergy analysis is performed since exergy analysis is uncommon in this specific field, which can assist for further comprehension of heat transfer. Re number at inlet is set 13000 for air as the working fluid and RNG k–ε approach is employed for turbulent model. The effect of oscillating tube on the main performance criteria including, drag coefficient, mean Nu number, average friction factor, exergy loss, and two parameters of Nu_ave/f and J/f is evaluated. Based on the obtained results, the fluctuation of the tube with an amplitude of 10° leads to highest efficiency factors compared to non-oscillating tube and tubes with the α_m=20°. The possible improvement can be resulted from the lower relative pressure drop and higher relative heat transfer improvement. The fluctuating arrangement has a noticeable impact on the outcome of both thermal and hydrodynamic performances of the tube banks. However, the higher turbulence generation rate can lead to a more improved heat transfer coefficient, but the combined effect of the tube geometry and fluctuation would decide the overall performance.