PERFORMANCE EVALUATION OF DEEP SPIRALLY CORRUGATED TUBES FOR SHELL-AND-TUBE HEAT EXCHANGERS

摘要

Extended performance evaluation criteria have been used to assess the benefit of replacing the smooth tubes with deep corrugated tubes in shell-and-tube heat exchangers. The goal is to assess the influence of characteristic parameters of the corrugated tubes: height-to-diameter ratio e/ D_i, relative pitch p/e, and relative helix angle β_*, on the thermodynamic efficiency in the case of condensers with steam condensing on the outside of the vertically or horizontally mounted tubes and water in forced convection (non-boiling) flow through the tubes. The geometrical parameters of the tubes studied were in the range of e/D_i = 0.05 ÷ 0.10, p/e = 5.4 ÷ 13.9, and β_* = 0.33 ÷ 0.63 for vertically mounted tubes and e/D_i = 0.05 ÷ 0.07; p/e = 4.6 ÷ 18.2 and β_* =0.40 ÷ 0.94 for horizontally established tubes. The thermodynamic optimum can be defined by the minimizing the entropy generation number compared with the relative increase of the heat transfer rate or relative reduction of the heat transfer area.