A novel type of shell and tube heat exchanger with modified fold helical baffles and twisted oblate tubes (STHXsFBTB) is proposed to seal the leakage areas in the shell center of the shell and tube heat exchanger with fold helical baffles (STHXsFB). The thermal and hydraulic properties of STHXsFB and STHXsFBTB for water chiller systems are investigated by numerical simulation. The influences of the configuration factors (screw pitch and tube diameter ratio, length width ratio and cutting ratio) on the thermal and hydraulic properties of STHXsFBTB are studied. Compared with STHXsFB, the heat transfer coefficient (h) of STHXsFBTB increases by 3.88%–8.05%, while the pressure loss (△P) decreases by 6.50%–7.38%, and the comprehensive heat transfer performance (Nu·f^−1/3) increases by 6.38%–10.35%. Moreover, as screw pitch and tube diameter ratio, length width ratio and cutting ratio increase, both h and Nu·f^−1/3 decrease. The influences of the length-width ratio and the cutting ratio on thermal and hydraulic properties of STHXsFBTB are tremendous, while the screw pitch and tube diameter ratio has a negligible effect. When the screw pitch and tube diameter ratio is 10, the length width ratio is 1.5 and cutting ratio is 0.35, the optimum configuration of STHXsFBTB is obtained.

提出了一种新型的具有改进的折叠螺旋折流板和扭曲扁管的壳管式换热器（STHXsFBTB），以利用折叠螺旋折流板（STHXsFB）密封壳管式换热器壳中心的泄漏区域。通过数值模拟研究了STHXsFB和STHXsFBTB在冷水机系统中的热力和水力特性。研究了构造因素（螺距和管径比，长度宽度比和切削比）对STHXsFBTB的热学和水力学性能的影响。与STHXsFB相比，STHXsFBTB的传热系数（h）增加3.88％–8.05％，而压力损失（△P）减少6.50％–7.38％，综合传热性能（Nu·f^−1/3）增加6.38％–10.35％。此外，随着螺杆螺距和管径比，长度宽度比和切削比的增加， h和Nu·f ^-1/3均减小。长宽比和切削比对STHXsFBTB的热和水力性能的影响很大，而螺距和管径比的影响可忽略不计。当螺距和管径比为10时，长宽比为1.5，切削比为0.35时，可获得STHXsFBTB的最佳配置。