Investigation on shell side performance in half-cylindrical desuperheating zone of ladder type helical baffle heat exchangers

The shell-side flow and heat transfer performance in half-cylindrical desuperheating zones of high pressure feedwater heaters were simulated by Fluent. The investigated structures include three ladder type helical baffle heat exchangers, i.e. the two unilateral ladder types with folded and inclined plane strip baffles, and the bilateral plane type, and two comparative schemes of eggcrate support type and double-segmental type and all baffle types are of three different baffle pitches. The visualized flow patterns in the desuperheating zone were demonstrated on special slices to clearly reveal the mechanisms and impacts of baffle configurations and geometrical parameters on thermal-hydraulic performances. The numerical results show that the shell-side heat transfer coefficients h(o) of all ladder type helical models are superior to those of both eggcrate support and double-segmental ones, among which the bilateral plane model has the best performances. The average values of h(o) and evaluation indexes h(o)Delta p(o)(-1) and h(o)Delta p(o)(-1/3) of nine helical models raise 2.99%, 149.50% and 36.26% respectively in contrast to those of the corresponding double-segmental models, and the average values of evaluation performance eta for schemes of three baffle pitches 80, 120 and 160 (mm) are respectively 1.202, 1.367 and 1.525.