Thermal performance escalation of cross flow heat exchanger using in-line elliptical tubes.

In the present research work, heat transfer and friction characteristics of in-line elliptical tubes are studied experimentally and numerically with the aiming to enhanced the thermal performance. The elliptical tubes with an aspect ratio (AR) of 0.35 and 0.50 and with circular tubes of the aspect ratio of 1 are selected for Reynolds number (Re) ranging from 5000 to 21000. The results indicate that the elliptical tube shows higher heat transfer rate with a significant reduction in the friction factor for the entire range of Reynolds number. The superior performance of the elliptical tube is often due to the aerodynamic cross-section profile of the tubes which promotes better heat transfer with a reduction in the frontal area of the tubes. The study is performed for the two different pitch to major axis ratios (PR) of 1.25 and 1.5, respectively. The results show that at a pitch ratio of 1.25 the elliptical tube with an aspect ratio of 0.50 leads to the superior heat transfer rate, while at pitch ratio of 1.50 elliptic tubes with an aspect ratio of 0.35 indicate better thermo-hydraulic efficiency relative to 0.50. [ABSTRACT FROM AUTHOR]