Heat Transfer and Flow Resistance Characteristics of Helical Baffle Heat Exchangers with Twisted Oval Tube

To overcome the defect of the significant increase in pressure drop when the heat transfer performance of helical baffle heat exchanger is improved, a novel helical baffle heat exchanger with twisted oval tube is proposed. Numerical simulation was done to exhibit the shell side heat transfer and flow characteristics with CFD software Fluent. The field synergy principle was used to evaluate the shell side performance. The results show that the flow velocity distribution on the shell side of the spiral baffle heat exchanger is more uniform and the velocity near the tube wall increases in the range of research parameters, as the circular tube is replaced by a twisted elliptical tube with the same perimeter length. Moreover, the helical baffle heat exchanger with twisted oval tube has better field synergy of velocity and temperature gradient, velocity and pressure gradient. The helical baffle heat exchanger with helix angle of 15° has better performance than that of circular tube, and its heat transfer coefficient is improved about 3.3% and pressure drop is reduced by 17.1%–19.1%. Hence, the comprehensive heat transfer performance is improved by 21.5%–22.5%. When the helix angle is 20°, the comprehensive heat transfer performance is increased by 16.1%–18.0% with heat transfer coefficient improvement of 3.6% and pressure drop reduction of 13.9%–16.5%.