Abstract: The V-type segmented heat exchanger is commonly used in the second generation of fan coil air conditioner. The uniform distribution of fin shape and enhanced surface makes the heat transfer potential under non-uniform airflow field hardly fulfills. The C-type heat exchanger is designed and Taguchi method is used to optimize the fin surface enhancement in the high and low air velocity region, respectively. Five schemes are selected for simulation comparatively, and condensed water drainage of zones with different bridges are simulated. Optimal scheme is determined and tested experimentally. Results show that the performance reaches the best with 1.4 mm bridge width, 0.6 mm bridge height and 4 bridges in low air velocity region, but 1.2 mm bridge width, 0.6 mm bridge height and 2 bridges in high air velocity region. The heat transfer enhancement of the C-type fin and the airflow field matches accurately with favorable drainage performance, when the fin surface structure is enhanced by segment, upper and lower parts of the fin are arranged asymmetrically, and the tube spacing is unequally designed. Compared with the V-type one, APF is 6.4% higher while the cost is 14.5% lower on average for the optimized C-type heat exchanger.

Key words: C-type fin, Non-uniform airflow, Heat transfer enhancement, Taguchi method, Asymmetric design