Design and analysis of heptane autothermal reformer for fuel cell applications

In this thesis, a reformer is designed to utilize heptane as a hydrocarbon source to produce sufficient hydrogen to generate 1 kW of power. In particular, the reformer is modeled as a non-isothermal, non-isobaric packed bed reactor. Heat is supplied to the reactor via a jacket and the performance is evaluated by modeling the reactor and jacket combination as a jacked packed bed reactor. The effect of temperature, pressure, oxygen to heptane ratio and steam to heptane ratio on the production of hydrogen is studied. Two different cases are considered: (1) Case I: heptane reforming as well as oxidation reactions occur in the reactor and (2) Case II: heptane reforming reactions occur in the reactor and heptane is combusted in the jacket. It is shown that the performance of the reactor system is better in Case II. In particular, it is shown that a reformer with an inside pipe diameter of 0.024m, outside pipe diameter of 0.041 m, reactor length of 0.185 m and the reactor volume of 8.4x10 -5 m3, operating non-isothermally in a temperature range of 373K-900K, inlet pressure of 2atm and initial steam to heptane ratio of 10 is able to produce sufficient hydrogen to generate 1 kW of power. The flow rate of heptane in the reactor is 7.6e-4 moles/sec and the flow rate of heptane in the jacket is 2.1e-4 moles/sec. It is observed that pressure drop is negligible throughout the reactor volume.