Abstract
In this study, a micro heat exchange-type hydrogen supplier (MHEHS) was successfully demonstrated as a fuel supply source for micro reforming methanol fuel cell (RMFC). The purpose of this study is integrating the micro channel heat exchanger (MCHE) and the micro channel reformer (MCR) by using the technique of micro electromechanical system (MEMS). In terms of the adequate integration, we are able to reuse the heat generated by the POM reaction. The heat generated is conducted to the cold side of the MCHE, providing enough heat for liquid methanol to start boiling. Meanwhile, the extremely hot hydrogen produced by POM reaction could be cool down to 60~80℃ since it is the working temperature of fuel cell. The geometric dimension of MHEHS is20×20×2.13mm^3, for which 2.13mm is the thickness. There are 18 micro channels with 240μm for both the hot side and the cold side of MCHE. In addition, it’s worth mentioning that the diverging micro channel is designed to suppress the back flow while boiling is occurring, and to improve and enhance the stability of two-phase flow. The MCR is a finger- type design with channel depth of 350μm, provided by the lab of Professor F.G.Tseng, and the depth of micro channel in MCR is350μm. The micro channel is designed to make oxygen mix with methanol steam and subsequently pass uniformly into the MCR. Consequently, the performance of producing hydrogen may be enhanced. Besides, the nanoparticle of Cu-Mn-Zn, developed and provided by the lab of Professor Y.T.Huang, is chosen to be the catalyst in MCR. The temperature at the inlet is measured to judge the stability of transporting precursor. Moreover, the high speed camera and Neutron Radiography (NR) are employed to observe the two-phase flow pattern in MCHE. Slug flow, annular flow, film break-up, droplet flow and dry out have been successfully observed . Finally, Gas Chromatography (GC) is used to analyze the component of the product, especially hydrogen. On the other hand, the effects of methanol flow rate, oxygen flow rate and the performance of MHEHS are studied, in terms of methanol conversion ratio, hydrogen production selectivity and CO production selectivity. A hydrogen selectivity up to 77.4% is obtained under the condition of V_MeOH= 0.04 sccm; V_(O_2 )= 10 sccm; q=22.5W in this research.