Flow and heat transfer performances of helical baffle heat exchangers with different baffle configurations

摘要

The flow and heat transfer performances of four helical baffle heat exchangers were numerically simulated. The exchangers exhibited an approximate spiral pitch and different configurations, i.e., a trisection circumferential overlap baffle scheme with a baffle incline angle of 20 degrees (20 degrees TCO), a quadrant circumferential overlap baffle scheme with a baffle incline angle of 18 degrees (18 degrees QCO), a quadrant end-to-end baffle scheme with a baffle incline angle of 18 degrees (18 degrees QEE), and a continuous helical baffle scheme with a baffle helical angle of 18.4 degrees (18.4 degrees CH). Velocity vectors superimposed pressure nephogram for meridian slice M1, transverse slices f and f1, and superimposed velocity nephogram for unfolded concentric combination slices CS2 and CS3 are presented. The heat transfer enhancement mechanisms of secondary flow were analyzed. Curves describing the local average heat fluxes of heat transfer tubes T1-T9 within a 60 sector region and those of concentric heat transfer tube layers N1-N4 are presented. The results show that the 20 degrees TCO scheme possesses the best market application value for its highest shell-side heat transfer factor j(o) and average comprehensive index (j(o)/f(o)). The 18.4 degrees CH scheme performs difficulty in manufacturing with continuous helical baffle but exhibits the worse performances in terms of jo and (C). 2015 Elsevier Ltd. All rights reserved.