Thermal energy transfer for green urban development: numerical investigation on the heat transfer and flow noise in heat exchangers with different helical and segmental baffles

Noise pollution in pipelines of heat exchangers has existed for a long time, which often results in severe equipment destruction and environmental pollution. To emphasize the importance of green urban development and satisfy the growingly stringent environmental noise policy, it is essential to investigate the thermal energy transfer process and develop low-noise heat exchangers while maintaining heat transfer capability. The shell and tube heat exchangers with helical baffles have clear advantages in enhancing heat transfer and reducing pressure drop, although the acoustic characteristics are not very distinct. This work numerically investigated the heat transfer and flow noise propagation mechanism inside heat exchangers, including path lines routes, sound pressure distributions, shell side pressure drops, heat transfer coefficients, and outlet sound pressure levels. The low-noise advantage of helical baffles in shell and tube heat exchangers has been proved. And the effect of different baffles has been analyzed from the perspective of multi-objective optimization. The results show that the helical baffle heat exchanger with β = 40° offers the best overall performance, which has a relatively higher h/Δp and a lower noise level. This paper's novelty lies in investigating the effect of different baffles on the flow-induced noise in shell and tube heat exchangers. It is innovative to perform a comprehensive evaluation of heat exchanger in flow noise, flow resistance, and heat transfer from the perspective of thermal energy transfer process. And it is a new trial to investigate the noise generation with fluid flowing across the tube bundles in integrated heat exchangers. The research on the heat transfer and flow noise in the shell and tube heat exchangers can not only emphasize the low-noise advantages of helical baffles and improve the comprehensive performance, but also provide a new design basis for the vibration and noise reduction in heat exchangers.