Hydrogen, due to its abundance in the universe, is replacing fossil energy sources such as coal, oil etc. which are running out quickly. Hydrogen has an energy value per unit mass of fuel burned, which is 120.7 kJ/g compared to any fuel type (Haryanto et al., 2005). Furthermore, during combustion, fossil fuels produce pollutants such as COx, NOx, SOx, CxHx, soot, ash and other organic compounds into the atmosphere which contribute to global warming. Hydrogen was discovered by Henry Cavendish in 1766 and named in 1783 by Antoine Lavoisier with the name originating from the words "hydro" and "geni" meaning "water" and "generator" because it burns to produce only water (Song, 2003) . It is present in combination with other elements such as oxygen in water, carbon in hydrocarbons and must be extracted. Other sources can be a variety of fossil and non-fossil resources such as coal, natural gas, liquefied petroleum gas, diesel, biomass and derived fuels such as methanol, ethanol and biodiesel (Haryanto et al., 2005). Hydrogen fuel cells are used to provide energy for transportation and mobile applications in the form of electricity directly from chemical energy to power laptops, vehicles or other applications where cost is not a big issue such as space technology, submarines etc. They are energy efficient, clean, flexible in fuel, not noisy, there are no vibrations and have smooth operation resulting in user comfort (Silveira et al., 2009). Furthermore, the fuel used in fuel cells has a higher energy density than batteries (Park et al., 2007), which is necessary for portable applications such as laptops, medical and telecommunications devices, and for military applications such as remote sensors (<20 W ), silent power generation and battery charging (200 W- 2 kW) and mobile...... middle of paper ...... method of removing or adding convective heat). Thus, the ultimate “success” of this technology will largely depend on modeling, understanding, and controlling temperature excursions. In this work, ethanol is reformed with steam in a non-isothermal tubular reactor which is coupled with combustion of ethanol in a recuperative manner where heat is transferred from the exothermic reaction zone through the channel walls. A complete three-dimensional geometry consisting of coflow and counterflow configurations is modeled. The authors studied the ethanol vapor reforming-based design configurations through one-dimensional models and experiments (Table 2), but a 3-D model was needed to fully explore the various transport processes in the configurations and study variations in the performance of the reactor due to hydrodynamics and heat and mass transfer characteristics.