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

Area of Science:

• Chemical Engineering
• Thermodynamics
• Energy Storage Systems

Background:

• Ammonia synthesis reactors are crucial for energy storage system performance.
• The Braun-type reactor is utilized to enhance heat release rate.
• Existing reactor designs require optimization for new applications.

Purpose of the Study:

• To redesign and optimize the Braun-type ammonia synthesis reactor.
• To analyze the impact of key parameters on reactor performance.
• To achieve minimum entropy generation and maximum exothermic rate.

Main Methods:

• A one-dimensional model based on finite-time thermodynamics was developed.
• Analyzed effects of molar flow rate, H2:N2 ratio, reactor length, and inlet temperature.
• Employed the NSGA-II algorithm for multi-objective optimization of seven parameters.
• Utilized fuzzy decision methods and deviation index to select the optimal reactor.

Main Results:

• The total exothermic rate is primarily influenced by the inlet molar flow rate.
• Optimization resulted in a 12.6% increase in total exothermic rate.
• A 3.4% reduction in total entropy generation rate was achieved.
• The optimized reactor design was identified from the Pareto front.

Conclusions:

• The optimized Braun-type reactor significantly improves performance over the reference design.
• Finite-time thermodynamics and NSGA-II provide effective tools for reactor optimization.
• Findings offer valuable guidance for the practical design and application of exothermic ammonia synthesis reactors.