Theoretical analysis of hydrogen production by variable volume membrane batch reactors with direct liquid fuel injection

• Direct injection of liquid fuel is combined with variable volume membrane batch reactor.
• Hydrogen production via methanol steam reforming is demonstrated in the hybrid reactor.
• Comprehensive reaction-permeation-transport model for the transient batch reactor is developed.
• Reactor model is validated against experimental results by comparison of predicted and measured operational parameters.
• Effects of heat and mass transfer limitation on reactor performance are investigated using model.

A direct liquid fuel injection/variable volume reactor integrated with a hydrogen selective membrane (CHAMP-DDIR) has been recently shown to be a promising new concept for hydrogen production in portable and distributed applications. The CHAMP-DDIR reactor performance has been analyzed using a simplified transport model with which conditions for maximum performance, e.g. highest volumetric power density, were identified. A prototype reactor demonstrated the ability to realize performance improvement, while also indicating a need for more a rigorous model for accurate exploration of the design and operation space. In this paper, we present a comprehensive reactor model which carefully considers the effects of heat and mass transfer, including rigorous treatment of multi-component species transport. The model is validated against experimental results through comparison of predicted and measured hydrogen production rate, reactor pressure, and temperature. The experimentally validated model is used to identify the relationship between CHAMP-DDIR design and operating parameters and the rate-limiting processes that govern reactor output. In addition, effects of heat and mass transfer limitations on CHAMP-DDIR performance are investigated by comparing the predictions among multiple cases with increasing level of complexity used for modeling the transport phenomena within the reactor.