Investigation on thermal-hydraulic performance of parallel-flow shell and tube heat exchanger with a new type of anti-vibration baffle and wire coil using RSM method

Abstract

To overcome the deficiencies of parallel-flow shell and tube heat exchanger with round rod baffles (RRB-STHX), STHX with a new type of anti-vibration baffle (hexagon clamping baffle) and equilateral triangle cross sectioned wire coils (HCBetsw-STHX) is proposed in this paper. Response surface methodology (RSM) is adopted to investigate its thermal-hydraulic performance. Baffle distance, coil pitch, coil diameter and Reynolds number are considered as four design parameters. Analysis is conducted based on CFD to acquire the objective functions (NuH, NuH/NuR, fH, fH/fR and PEC) for different combination of design parameters. The RSM with Central Composite design is used to identify the relationships between the objective functions and the design parameters. Variances of the linear term, quadratic term and interactive term for design parameters in the response variables are analyzed. The mechanism of heat transfer enhancement of HCBetsw-STHX is illustrated from the view of field synergy theory. The results indicate that the heat transfer enhancement of HCBetsw-STHX is quite better than that of RRB-STHX. In the given design space, the NuH/NuR is in the range of 1.335–1.720; the fH/fR is in the range of 5.462–12.936. The most significant factor on NuH is Reynolds number, while the most significant effect factor on NuH/NuR, fH, fH/fR and PEC is coil pitch. The sensitivity of three objective functions (NuH, fH and PEC) to design parameters is explored. In addition, the design parameters optimization for the maximum value of NuH and PEC and that for the minimum value of fH are also carried out and corresponding flow structures are shown and illustrated.