Renewable methanol is considered a promising carrier for sustainable hydrogen due to its convenience in storage and transportation. Methanol steam reforming (MSR) using exhaust heat from industrial boilers can further enhance energy efficiency. However, existing methanol reforming systems still face challenges in terms of matching with industrial boilers, heat exchanger compactness, and adaptability to fluctuations in exhaust gas conditions. To address these issues, this study proposes the design of a modular methanol reforming system driven by the exhaust heat of small industrial boilers and develops a three-dimensional multiphysics simulation model to investigate the heat transfer and reaction characteristics within the reactor. The results indicate that, within the ranges of exhaust heat temperature (220–270 °C), flow rate (0.4–1.2 g/s), and channel spacing (60–100 mm), increasing the exhaust heat temperature enhances the endothermic reforming process, while decreasing the channel spacing improves heat transfer and increases methanol conversion. The reactor with a 60 mm channel spacing achieves a conversion ratio of up to 95.3% at a flow rate of 0.4 g/s. Although the hydrogen yield increases with flow rate, the single-pass conversion ratio decreases due to shorter residence time and increased load per unit volume. Compared to traditional fixed-structure reactors, the proposed modular system allows flexible matching of scale and heat exchange capacity through adjustable channel configurations, enhancing adaptability to fluctuations in industrial exhaust temperature and load. This design improves the utilization efficiency of low-grade waste heat and offers a practical engineering solution for sustainable distributed hydrogen production.

This study aims to explore and propose a design-oriented methodology for solar–thermal methanol reforming (ST-MSR) hydrogen production equipment suitable for marine applications. To address key challenges such as the intermittency of solar energy, spatial and environmental constraints on board ships, operational safety, and user experience, a multidisciplinary integrated-design decision-making framework is established. First, the Kano model is employed to systematically analyze the latent needs of target users regarding ST-MSR equipment, while the analytic hierarchy process (AHP) is used to determine the weighting of evaluation criteria. Second, the theory of inventive problem solving (TRIZ) is applied to generate innovative conceptual design solutions. Finally, the technique for order preference by similarity to an ideal solution (TOPSIS) is adopted to conduct a multi-dimensional comprehensive evaluation and optimization-based selection of the conceptual alternatives. The optimal design scheme is thus identified in terms of energy performance, product characteristics, user experience, economic feasibility, and environmental adaptability. The results indicate that the microchannel and phase-change thermal-storage integrated solar–thermal-tracking chemical reactor achieves the highest comprehensive evaluation score among the proposed schemes, demonstrating superior performance in terms of safety, energy efficiency, and adaptability to marine environments. This research provides a systematic industrial design methodology and practical reference for the design and product development of clean energy equipment for ships, contributing to the green and sustainable transformation of the maritime industry.