To address the insufficient heat transfer performance of shell-and-tube heat exchangers under low Reynolds number conditions

this study aims to reveal the effects of shell-side leakage flow and tube-side enhancement structures on thermal-hydraulic performance

and to propose effective heat transfer enhancement methods. Experimental investigations are conducted under low Reynolds number conditions. The leakage flow caused by the gap between baffles and the shell wall is analyzed. The thermal-hydraulic characteristics with and without leakage flow baffles are compared. Meanwhile

a heat transfer model for low Reynolds number flow inside tubes is developed

and the enhancement effect of twisted tapes is investigated. The results show that shell-side leakage flow weakens flow disturbance and reduces heat transfer performance. After installing leakage flow baffles

the overall heat transfer coefficient increases by 4.92%~ 13.22%

while the flow resistance increases by 15.4%~59.6%. Further analysis indicates that the dominant thermal resistance is mainly located on the tube side at low flow velocity. The developed tube-side heat transfer model shows high prediction accuracy. With twisted tapes inserted into the tubes

the overall heat transfer performance increases by 21.2%~38.8%. The research results are of great significance to the design and performance verification of shell and tube heat exchangers

and also of great significance to energy conservation and emission reduction in industrial systems.