Heat transfer characteristics of staggered wing-shaped tubes bundle at different angles of attack

An experimental and numerical study has been conducted to clarify heat transfer characteristics and effectiveness of a cross-flow heat exchanger employing staggered wing-shaped tubes at different angels of attack. The water-side Re-w and the air-side Re-a were at 5 x 10(2) and at from 1.8 x 10(3) to 9.7 x 10(3), respectively. The tubes arrangements were employed with various angles of attack theta(1,2,3) from 0A degrees to 330A degrees at the considered Re-a range. Correlation of Nu, St, as well as the heat transfer per unit pumping power (epsilon) in terms of Re-a and design parameters for the studied bundle were presented. The temperature fields around the staggered wing-shaped tubes bundle were predicted by using commercial CFD FLUENT 6.3.26 software package. Results indicated that the heat transfer increased with the angle of attack in the range from 0A degrees to 45A degrees, while the opposite was true for angles of attack from 135A degrees to 180A degrees. The best thermal performance and hence the efficiency eta of studied bundle occurred at the lowest Re-a and/or zero angle of attack. Comparisons between the experimental and numerical results of the present study and those, previously, obtained for similar available studies showed good agreements.