Numerical investigation on the shell and tube heat exchanger with baffle leakage zones blocked

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.