In the context of the "dual carbon" goals and the rapid development of renewable energies

solid oxide electrolysis (SOE) based hydrogen production and its derivatives present a novel approach to addressing the consumption of renewable power. High temperature operation of SOE necessitates the balance of plants such as heat exchangers and fans to maintain the thermodynamic equilibrium of the system. Proper heat exchanger design is critical for enhancing system compactness and energy efficiency. This paper proposes a multi-objective optimal design method for multi-stream compact heat exchangers based on non-dominated sorting genetic algorithm. It optimizes both the dimensional parameters and fin configurations of the heat exchanger. It also optimizes the layer arrangement of the heat exchanger by taking the mean square deviation of cumulative heat load as the index. Focusing on power-to-methane systems

the study demonstrates that fin frequency is a key factor influencing system compactness. With the fin frequency increases from 444 to 786 m−1

the specific surface area of the heat exchanger increases from 643 to 1116 m2/m3

while the friction factor and flow power consumption increase by 10.7% and 0.2 kW respectively. Optimizing the layer arrangement reduces the mean square deviation of cumulative heat load by 0.6 kW. For the gas-gas heat exchanger in power-to-methane system

compared with two-stream heat exchangers (28 kW)

the compact four-stream heat exchanger (35 kW) reduces the volume by 88%. This method optimizes the dimension

fin configurations

and layer arrangements of multi-stream plate-fin heat exchangers

providing insights for the high-temperature application of multi-stream heat exchangers.