Selection & calculation of the twist flat-tube heat exchanger 

 

 

They chose two units of twist flat-tube heat exchangers(the No. is LCLF600-2.5-74.5-6/25-6 (ST = 250)) by calculation instead of the initial two units of bow baffle plate heat exchangers(No. BES800-2.5-145-6/25-6 (B = 300)). The heat transfer surface of every unit nearly saved the double. Considering the pressure drop of shell pass, and first use of this type heat exchanger, we chose DN600mm heat exchanger. In the structural parameters, we still chose Φ 25 mm heat transfer tube, tube pitch is 32 mm, arrangement is square turn 45°, to facilitate the flow and the cleaning in the shell pass. We selected the optimal lead of twist flat-tube in single tube heat transfer experiment: 200, 250 and 300 mm. For the same lead twist flat-tube, the heat transfer and resistance performance of Φ 25 mm tube is obviously better than theΦ19 mm tube. The lead also has a direct relationship with the heat transfer coefficient, the lead is too small, flow velocity increased, point contacts of helix increased, it strengthened the function of wake flow, and improved the heat transfer coefficient, but increased the resistance; the lead is too large, the velocity is almost not change, heat transfer effect is not obvious. Therefore, we chose the lead for 250 mm.

 

Twist flat-tube heat exchanger