Many attempts have been made to improve heat transfer for thermally integrated microchannel reforming reactors. However, the mechanisms for the effects of design factors on heat transfer characteristics are still not fully understood. This study relates to a thermochemical process for producing hydrogen by the catalytic endothermic reaction of methanol with steam in a thermally integrated microchannel reforming reactor. Computational fluid dynamics simulations are conducted to better understand the consumption, generation, and exchange of thermal energy between endothermic and exothermic processes in the reactor. The effects of wall heat conduction properties and channel dimensions on heat transfer characteristics and reactor performance are investigated. Thermodynamic analysis is performed based on specific enthalpy to better understand the evolution of thermal energy in the reactor. The results indicate that the thermal conductivity of the channel walls is fundamentally important. Materials with high thermal conductivity are preferred for the channel walls. Thermally conductive ceramics and metals are well-suited. Wall materials with poor heat conduction properties degrade the reactor performance. Reaction heat flux profiles are considerably affected by channel dimensions. The peak reaction heat flux increases with the channel dimensions while maintaining the flow rates. The change in specific enthalpy is positive for the exothermic reaction and negative for the endothermic reaction. The change in specific sensible enthalpy is always positive. Design recommendations are made to improve thermal performance for the reactor.

Like electricity, hydrogen is an excellent energy carrier, as it can be produced from many different and abundant precursors, such as natural gas, coal, water, and renewable energy. The use of hydrogen in fuel cells, particularly in the transport sector, will make it possible to diversify the energy supply, take advantage of domestic resources, and reduce oil imports dependence. Unlike other fuels, hydrogen (H₂) can be generated and consumed without emitting carbon dioxide (CO₂). This results in great ecological benefits and fundamental challenges. Hydrogen can operate in a closed and inexhaustible cycle based on the cleanest, most abundant, and elemental substances: water, oxygen, and hydrogen. If hydrogen is generated using light, heat, and electricity produced from solar, wind, or nuclear energy, hydrogen becomes a versatile and universal means of storing and transporting energy and a necessary element for future energy systems that operate without environmental pollution, CO₂, and other gases that contribute to the greenhouse effect. Hydrogen is necessary to eliminate environmental pollution and stabilize the composition of the planet’s atmosphere and climate. This paper investigates different methods of hydrogen production in the term of their technological and economic aspects. This paper shows that thermochemical methods dominate the hydrogen market while emerging electroreduction methods are developing fast, which might turn the tide in the future.