Heat Transfer Experiments of Mini-Tube Bank

Heat transfer and flow behavior in the mini rod bank were examined. The tubes are simulated with a 1 mm diameter nickel wire. The tube bank was composed of the 5×5 square-lattice array and the 5×5 staggered array. The tube banks were arranged in the flow channel of 30 mm wide or 15 mm wide, 15 mm high and 480 mm long. Water was used as the test fluid. A flow rate was varied in the range of the Reynolds number Re = uD/ν of 1 ∼ 800, where D is the tube diameter. The approaching velocity of fluid in the channel was in the range of 0.0036 m/s ∼ 0.68 m/s. Experiments were performed at atmospheric pressure. The measured heat transfer coefficients of the rows after the second row were lower than those of the first row and the difference between those increased as the Reynolds number was increased. The difference turned to decrease around Reynolds number = 50 in the 15 mm wide test section experiments of the square–lattice array and around Reynolds number = 200 in the 30 mm wide test section experiments of the staggered array. The heat transfer coefficients reached back to the first row value around Re = 400 in the former experiments. It was confirmed through the present results and the previous results that the heat transfer in the rear rows is deteriorated by the flow stagnation in the wake region of the preceding rod and the deterioration is recovered as the Reynolds number is increased since the wake region becomes disturbed.