Shell Side Flow and Heat Transfer Performances of Trisection Helical Baffle Heat Exchangers

Abstract

The flow and heat transfer performances of three trisection helical baffle heat exchangers with different baffle shapes and assembly configurations, and a continuous helical baffle scheme with approximate spiral pitch were numerically simulated. The four schemes are two trisection helical baffle schemes of baffle incline angle of 20° with a circumferential overlap baffle scheme (20°TCO) and a end-to-end helical baffle scheme (20°TEE), a trisection mid-overlap helical baffle scheme with baffle incline angle of 36.2° (36.2°TMO), and a continuous helical baffle scheme with baffle helix angle of 16.8° (18.4°CH). The pressure or velocity nephograms with superimposed velocity vectors for meridian slice M1, transverse slices f and f1, and unfolded concentric hexagonal slices H2 and H3 are presented. The Dean vortex secondary flow field, which is one of the key mechanisms of enhancing heat transfer in heat exchangers, is clearly depicted showing a single vortex is formed in each baffle pitch cycle. The leakage patterns are demonstrated clearly on the unfolded concentric hexagonal slices. The results show that the 20°TCO and 18.4°CH schemes rank the first and second in shell-side heat transfer coefficient and comprehensive indexes ho/Δpo and ho/Δpo1/3. The 20°TEE scheme without circumferential overlap is considerably inferior to the 20°TCO scheme. The 36.2°TMO scheme is the worst in both shell-side heat transfer coefficient and comprehensive index ho/Δpo1/3.