Numerical investigation on double tube-pass shell-and-tube heat exchangers with different baffle configurations

Abstract

Thermo-hydraulic performances of shell-and-tube heat exchangers with different baffle types have been widely evaluated using computational fluid dynamics (CFD) methods. In this paper, double-tube-pass shell-and-tube heat exchanger (DTP-STHE) is proposed to improve the recovered heat quality from the point of exergy analysis. Results reveal that the recovered heat quality in DTP-STHE is almost twice as that in single-tube-pass shell-and-tube heat exchanger (STP-STHE). Furthermore, the heat transfer rates in both heat exchangers are nearly the same. In all heat exchangers, increasing the mass flow rate of water in shell side can increase the exergy utilizing efficiency and heat transfer rate, but the mass-weighted average temperature of water decreases. In order to investigate thermo-hydraulic performances of different DTP-STHEs, three kinds of DTP-STHEs with segmental, helical and flower baffles respectively are compared under the same conditions. Results show that flower baffles produce the lowest pressure drop and lowest heat transfer coefficient. For better evaluating the economic performance of these three kinds of heat exchangers, heat transfer rate per effective pumping power (i.e., QH/P0) is introduced. The simulation results show that QH/P0 of flower baffle is the highest and QH/P0 of segmental baffle the lowest.