Sharif Digital Repository

The idea of improving performance of internal combustion engines has always been important for researchers and manufacturers. In recent decades, due to limited resources of fossil fuels and introduction of vehicle emission regulations, researchers have undertaken more efforts to achieve goals such as increased horsepower, reduced fuel consumption and pollutant emissions reductions. Homogeneous charge compression ignition engine is a modern and efficient design that has attracted attention of many researchers. In[[ these engines, homogenous mixture of fuel and air enters into the combustion chamber and with a mechanism of self ignition, produces more power and has less fuel consumption... 

The advent and advancement of technology through the conversion of Gas-Synthesis (a mixture of CO and H) into liquid hydrocarbons, by Fischer- Tropsch synthesis (FTS) gives more promising future in this field. Metals such as cobalt, nickel, zinc and iron are used as catalysts for FTS. Studies have shown that the surface structure of metal catalyst has a great influence on the process, and leads to different products and transition states. Iron has been known the most used and the most cost-effective metal catalyst in FTS. Different surfaces of Iron have different catalytic roles. In our work, Fe(100) -that is the most stable after Fe(110) and is known as the most active iron’s surface in... 

Ethylene is a cornerstone of the petrochemical industry, serving as the primary feedstock for polyethylene, ethylene dichloride, ethylene oxide, ethylbenzene and many other derivatives. The conventional production route, steam cracking of hydrocarbons, relies on extremely high furnace temperatures at near-atmospheric pressure. Although catalytic dehydrogenation of paraffins has long been practiced as an alternative, its commercial performance is constrained by equilibrium limitations, rapid coke deposition and irreversible catalyst deactivation. Oxidative dehydrogenation of ethane (ODHE), in which oxygen is introduced in a controlled manner, offers a promising means of overcoming these...