Fin optimization of tube-fin heat exchangers is a research hotspot

and there are few studies on tube types. A design method for a special-shaped tube with the same hydraulic radius as a circular tube is proposed. A numerical calculation model of the air-side heat transfer of the special-shaped tube-and-fin heat exchanger was established. The effects of tube shape

windward direction

and fin spacing on the performance of special-shaped tube-and-tube-fin heat exchangers were investigated. The results showed that for the double-row special-shaped tube heat exchanger

when the first row of tubes exposed to the air is larger than the second row

the air flow is the most uniform and the pressure drop is the smallest

delivering the best overall performance in the upwind direction. When the round tube

elliptical tube

special-shaped tube

and flat tube-fin heat exchangers are compared

the best resistance characteristic and comprehensive performance is the special-shaped tube at a air velocity of 4 m/s. The pressure drop is lower than that of the round tube by 31.86%

the value of performance enhancement evaluation index (Nu/Nu0)/(f/f0) is 1.456

mainly due to the large net flow area of the air between the tubes

and there is less disturbance when flowing through the heat exchanger. In addition

the larger the fin spacing

the greater the influence of the tube type on the air-side flow and heat transfer. The large fin spacing has better improvement effects on the resistance performance and overall performance of the heat exchanger than the small fin spacing.