Experimental and numerical study on heat transfer and fluid flow characteristics of slotted fin-and-tube heat transfer surfaces

Air side heat transfer and fluid flow characteristics of two-row slotted fin-and-tube heat transfer surface with X-type strip arrangement were studied experimentally and numerically. The heat transfer and friction factor correlations were obtained in a wide range of Reynolds number. It is found that the slotted fin-and-tube heat transfer surfaces have excellent performance compared with the plain plate fin heat transfer surfaces and the performance of X-type two-side strip fin surfaces is better than that of one-side strip fin surfaces. By numerical method, the fin efficiency curves for X-type two-side strip fin surfaces were achieved. From the viewpoint of field synergy, the air velocity and temperature fields between the two neighboring fin surfaces and the distribution of local heat transfer coefficient and pressure drop in flow direction were analyzed. The results show that the heat transfer enhancement of slotted fins is caused by the improvement of the synergy between the velocity field and the temperature gradient.