Comparative numerical analysis of various baffled heat exchangers with existence of baffle-to-shell clearance

The presence of baffle-to-shell clearance compromises shell side thermal efficiency of shell-and-tube heat exchangers (STHEs). This study investigates the effectiveness of sealing strips in mitigating flow maldistribution for the shell side of STHEs with such clearance . Periodic numerical models were established and validated for three typical STHE configurations: segmental, helical and trefoil-hole baffled exchangers. The effect of sealing strips under triangular and squared tube layout across typical baffle configurations was evaluated quantitatively with respect to shell-side performance. The sealing strips increased both heat transfer coefficient and pressure drop in segmental and helical configurations; however, their influence on trefoil-hole baffled exchangers was negligible. The comprehensive performance index, h (Δ p ) -1/3 , increased by 4.63–6.76% and 2.09–4.12% for segmental baffled STHEs with sealing strips in staggered and aligned tube arrangement, respectively. Whereas for corresponding helical configurations, the same index decreased by 23.01–26.62% and 19.51–21.95%, indicating the limited or even negative effect of sealing strips for helical baffles. The acceptability of sealing strips in helical and trefoil-hole baffled STHEs, especially for multiple-pass design and diverse operating conditions, warrants dedicated investigation. Shell side comprehensive indexes h (Δ p ) -1/3 of corresponding configurations.The comprehensive performance index, h (Δ p ) -1/3 , increased by 4.63–6.76% and 2.09–4.12% for segmental baffled STHEs with sealing strips in staggered and aligned tube arrangement, respectively. Whereas for corresponding helical configurations, the same index decreased by 23.01–26.62% and 19.51–21.95%, indicating the limited or even negative effect of sealing strips for helical baffles. The effect of sealing strips in trefoil-hole baffled STHEs is negligible.(Here the string of SS represents the square tube arrangement with sealing strips, TS refers to triangular layout with existence of sealing strips, SN denotes square pattern without sealing strips while TN addresses no sealing strips with triangular pattern. “H-SS” means Helical baffled STHEs with the square tube arrangement and sealing strips, while “S-SS” corresponds to the Segmental baffled STHEs. Other configurations can be referred to this consistent notation. And “Tre-TS” and “Tre-TN” denote trefoil-hole plates with employment and absence of sealing strips in triangular tube layout, respectively.)