Analysis of flow dead zone in shell side of a heat exchanger with torsional flow in shell side

•A novel heat exchanger with torsional flow in shell side was presented.•Flow dead zone induced by baffle was discussed quantitively and qualitatively.•Distribution and volume fraction of flow dead zone on heat transfer was studied.•Change of flow dead zone in shell side with baffle arrangement was discussed.•An LDV experiment was carried out to verify numerical simulation. In order to improve the heat transfer efficiency of the heat exchanger, the characteristics of dead zone and its effect on thermal performance in the shell side of a novel heat exchanger with torsional flow were discussed. The residence time distribution method combining with the CFD were used to analyze quantitatively and qualitatively the flow dead zone. By optimizing the baffle arrangement, the minimum flow dead zone is reduced to 2.76%, and the maximum thermal performance is increased to 13.56%. The results show that the fraction of dead zone volume slightly from 10.42% to 10.28% when the Reynolds number increase from 4000 to 12,000 in the shell side of the heat exchanger with segmental baffle, and that decreases from 11.66% to 9.87% in the torsional flow heat exchanger. The dead zone in the shell side of heat exchanger with torsional flow is mainly affected by the shell inlet and the corner between the cylinder wall and the baffle. The volume ratio of the dead zone between the reverse arrangement and the forward arrangement are 24.11%, 27.96% and 31.65% respectively. The research results and methods provide a theoretical basis for the analysis and optimization of structure of heat exchanger.