Heat transfer uniformity of a flat plate impinged by movable double nozzles: An experimental implementation

Abstract

The heat transfer characteristics of jet impingement from movable double nozzles on a fixed flat hot plate are investigated experimentally in the present implementation. The velocity of movable nozzles (Vn) is varied as 200, 400, and 600 mm/min, at a Reynolds number (Re) of 8000, 12000, 16000, 20000, and 24,000 at a nozzle-to-plate distance (H/D) of 1, 3, 5, and 7, and a spacing distance (S/D) of 2, 3, and 4. The behavior of heat transfer over a flat plate impinged by double movable nozzles in comparison to fixed ones is presented. The influences of H/D, S/D, Re and Vn on the average Nusselt number (Nu¯) and heat transfer uniformity (U) are examined for fixed and movable double nozzles cases. The results indicate that the Nu¯ and U are affected by the movement of nozzles, and the fixed case has higher heat transfer more than the movable case, whereas the movable case obtains better uniformity of heat transfer. The maximum Nu¯ equals 29 obtained at Re of 24000, H/D of 1, and S/D of 2 for the fixed case. By increasing the Vn, the U is enhanced, and its maximum value of 89.6 % is obtained at Vn of 600 mm/min, H/D of 1, S/D of 2, and Re of 24000. Additionally, multiple regression analysis is employed to acquire empirical correlations to assess the Nu¯ and U for fixed double nozzles as well as movable double nozzles as functions of Re, H/D, S/D, and Vn.