科研之友
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摘要
Onboard fuel reforming to produce hydrogen for portable fuel cell applications has been widely studied because the liquid has a high volumetric density as an energy storage medium. Several portable fuel reforming devices presented in the literature attempt to scale down the designs of traditional large-scale unit operations, an approach that becomes suboptimal as the size of the application is reduced. Unique reactor designs in which the various unit operations are combined in a synergistic manner are required to achieve higher energy densities and more compact reactors. Spraying a finely atomized liquid directly onto a hot catalyst is one such method that has been experimentally demonstrated. This work focuses on developing a fundamental understanding of this approach and optimizing it by utilizing a droplet generator array with precise control over the droplet spacing, diameter, velocity, and trajectory, thus providing ultimate control over the reactor performance. The regular nature of the droplet generator array also enables modeling on a reactor-unit-cell basis with minimal empiricism, which can be used to optimize the reactor performance. The steady-state unit-cell model developed in this work accounts for the transport and evaporation of the droplet stream, impingement and subsequent film accumulation and vaporization, and gas-phase transport and reaction. The key components of the model were validated using relevant results from the literature to establish confidence in applying the complete model to predict reactor performance. Further, a reactor prototype mimicking the reactor unit cell used in the simulations was constructed and used to experimentally validate the comprehensive transport reaction model for the specific case of methanol steam reforming. In a companion article, this complete model was used to study the effects of reactor operating parameters on conversion, selectivity, and power density, aiming at an optimal reactor design.
- 出版日期2011-8-17
