Multi-Objective Optimization of Braun-Type Exothermic Reactor for Ammonia Synthesis

Abstract

The exothermic reactor for ammonia synthesis is a primary device determining the performance of the energy storage system. The Braun-type ammonia synthesis reactor is used as the exothermic reactor to improve the heat release rate. Due to the entirely different usage scenarios and design objectives, its parameters need to be redesigned and optimized. Based on finite-time thermodynamics, a one-dimensional model is established to analyze the effects of inlet gas molar flow rate, hydrogen–nitrogen ratio, reactor length and inlet temperature on the total entropy generation rate and the total exothermic rate of the reactor. It’s found that the total exothermic rate mainly depends on the inlet molar flow rate. Furthermore, considering the minimum total entropy generation rate and maximum total exothermic rate, the NSGA-II algorithm is applied to optimize seven reactor parameters including the inlet molar flow rate, lengths and temperatures of the three reactors. Lastly, the optimized reactor is obtained from the Pareto front using three fuzzy decision methods and deviation index. Compared with the reference reactor, the total exothermic rate of the optimized reactor is improved by 12.6% while the total entropy generation rate is reduced by 3.4%. The results in this paper can provide some guidance for the optimal design and application of exothermic reactors in practical engineering.

Four-Objective Optimization for an Irreversible Porous Medium Cycle with Linear Variation in Working Fluid’s Specific Heat

“…With the increase in OOs, there are contradictions among different OOs. To select the optimal result under the coexistence of multiple OOs, many scholars have carried out multi-objective optimization (MOO) [ 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 ] by NSGA-II [ 78 ]. Li et al [ 68 ] established a regenerative Brayton cycle model and carried out MOO on the , and dimensionless thermal economic performance.…”

“…Baghernejad et al [ 72 ] took exergy efficiency, overall cost rate and exergy unit cost of generated electricity as OOs, and performed MOO on the combined Brayton and Rankine cycle. Xie et al [ 73 ] performed MOO on the molar flow rate, reactor lengths and inlet temperatures of Braun-type exothermic reactor for ammonia synthesis. Shi et al [ 74 ] and Ge et al [ 75 ] used , , and as OOs and performed MOO for the diesel [ 74 ], dual [ 75 ] and MHD [ 76 ] cycles.…”

Thermodynamic Optimization of Ammonia Decomposition Solar Heat Absorption System Based on Membrane Reactor

“…Kong et al [26][27][28] optimized the temperature distribution of the HI decomposition membrane reactor with the objectives of highest HI conversion rate, maximum hydrogen yield, and minimum entropy generation rate. In addition, FTT has shown broad prospects on the analysis and optimization of reactors for ammonia synthesis [29], sulfuric acid decomposition [30,31], methane steam reforming [32,33], methanol synthesis [34,35] and so on.…”

Multi-Objective Constructal Design for Quadrilateral Heat Generation Body with Vein-Shaped High Thermal Conductivity Channel

“…Therefore, the multi-objective optimization (MOO) not only adapts to the engineering design requirements but also promotes the update and replacement of the heat dissipation design strategy of electronic devices. The Non-dominated Sorting Genetic Algorithm II (NSGA-II) [ 57 ] with an elite strategy has been successfully applied to many engineering designs [ 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 ]. In particular, some scholars apply the NSGA-II algorithm to the study of constructal design with different optimization objectives.…”