Constructal design for a boiler economizer

Carrying out structural and parametric design and performance optimization of boiler economizer is important to improve comprehensive performance of supercharged boiler. By application of constructal theory, the design of a boiler economizer is conducted in this paper. Firstly, a complex function composed of linear weighted sum of heat transfer rate and power consumption rate is minimized. The total heat transfer area is given, and outer diameter, group number and row number of the serpentine tubes are taken as design variables, respectively. The optimal performance of the boiler economizer is gained. It reveals that in the limited ranges of the design variables, the optimal dimensionless outer diameter, optimal group number and optimal row number of the serpentine tubes are 0.92, 16 and 8, respectively, which individually lead to the minimum complex function. The complex functions derived by individually optimizing the outer diameter, group number and row number of the serpentine tubes are decreased by 5.7%, 4.9% and 5.0%, respectively. Secondly, multi-objective optimization based on non dominated sorting genetic algorithm (NSGA-II) is also conducted, and the Pareto frontier is obtained. The research results of this paper will provide certain theoretical guidelines for structural and parametric designs of various boiler economizers. (c) 2021 Elsevier Ltd. All rights reserved.