Numerical study of structural parameters of perforated baffle on heat transfer enhancement in coiled elastic copper tube heat exchanger

To bridge the research gaps regarding the heat transfer enhancement characteristics of coiled elastic copper tube (CECT) by spiral baffle, the CECT heat exchangers equipped with perforated and those with non-perforated spiral baffles (CECT-WP, CECT-NP) are presented. A two-way fluid–structure interaction method is utilized to numerically study the effects of the baffle helix turn number and perforation diameter on fluid flow and heat transfer at different inflow Reynolds numbers. The results show that there exists an optimal helix turn number and perforation diameter for the best heat transfer performance. Compared with CECT-NP, when the helix turn number ranges from 5 to 9, the JF-factor of CECT-WP is improved by up to 4.28 % at helix turn number of 8; when the baffle perforation diameter ranges from 12 to 24 mm, the JF-factor of CECT-WP is improved by up to 4.02 % at perforation diameter of 21 mm. Moreover, the structure of the CECT-WP is further optimized by reducing the number of spiral baffles from four to two, and ultimately to one. The vibration-enhanced heat transfer and overall heat transfer performances are found to be the best with one spiral baffle, showing improvements of up to 1.35 % and 4.24 %, respectively. Installing perforated spiral baffles in the CECT heat exchanger is an effective technique for improving overall heat transfer performance and has enlightening significance for engineering applications.