Numerical Study of Flow and Heat Transfer Characteristics of Shell-and-Tube Molten Salt Electric Heater with Circularly Perforated Baffles

Numerical simulations of the flow and heat transfer characteristics of four shell-and-tube molten salt electric heaters with different perforation rates was conducted. Shell-and-tube electric heaters have the same geometry and tube arrangement, and all of them use single segmental baffles, but there exist four different baffle openings (phi), i.e., 0%, 2.52%, 4.06%, and 6.31%. The results indicated that the reasonable baffle opening could significantly reduce the shell-side pressure drop, effectively decreasing the shell-side flow dead zone area. They can eliminate the local high-temperature phenomenon on the surface of electric heating tubes, but the heat transfer coefficient is slightly decreased. All perforated schemes significantly reduce shell-side pressure drop compared to the baseline solution without open holes. In particular, the phi=6.31% scheme exhibits the optimal performance among all the schemes, with a maximum reduction of up to 50.50% in shell-side pressure drop relative to the unopened holes scheme. The heat transfer coefficient is the highest for phi=0%, exhibiting a range of 5.26% to 5.73%, 5.14% to 5.99%, and 7.31% to 8.54% higher than phi=2.52%, 4.06%, and 6.31%, respectively, within the calculated range. The composite index h/(Delta p)1/3 was higher for all open-hole solutions than that for the unopened-hole solution. The best overall performance was for phi=6.31%, which improved the composite index by 15.29% to 17.18% over the unopened-hole solution.