Experimental study and motion parameter optimization of the shell side of a gas-phase rotating shell-and-tube heat exchanger based on an improved NSGA-II algorithm

Abstract

In the process of food drying, heat exchangers commonly face issues of low heat transfer efficiency and poor energy performance. This study focuses on a novel gas-phase rotary shell-and-tube heat exchanger, analyzing the effects of operational parameters (shell-side rotational speed and hot air velocity) on its shell-side heat transfer performance and pressure drop losses through a series of univariate experiments. Furthermore, an improved NSGA-II algorithm is proposed, incorporating adaptive operational mechanisms and an adaptive fuzzy penalty mechanism. This method, combined with extreme-value entropy weighting and the weighted sum method of ideal solution proximity, is used to filter the Pareto front solutions and determine the optimal operational parameter combination. The validity and accuracy of the optimal parameter combination were verified through a combination of experimental tests and numerical simulations, with the shell-side energy efficiency quantitatively assessed based on the thermal performance-to-pressure drop ratio. The results indicate that, under constant shell-side rotational speed, the Nusselt number increases with increasing hot air velocity. Pressure drop losses also rise with increasing hot air velocity, exhibiting an approximately exponential growth trend. When the hot air velocity is within the range of 2 m·s⁻¹ to 10 m·s⁻¹, the trends observed in both experimental and simulation results are consistent, with average error rates of 2.13 % for the Nusselt number and 3.46 % for the pressure drop, confirming the reliability of the numerical model. To validate the accuracy of the optimal parameter combination (shell-side rotational speed of 22.77 r·min⁻¹ and hot air velocity of 7.91 m·s⁻¹) obtained using the improved NSGA-II algorithm, the experimental and simulation results were compared. The differences between the three results were minimal, with an average error rate of 3.26 %, demonstrating the exceptional prediction accuracy and optimization performance of the new algorithm. Based on the comprehensive performance analysis of the optimization results, the thermal performance-to-pressure drop ratio is approximately 2.86, indicating that the heat transfer and energy efficiency of the shell-side are highly effective under this parameter combination. The findings provide a theoretical basis and data support for the design and optimization of gas-phase rotary shell-and-tube heat exchangers.