mohammad javad azarhoosh

In this study, hydrogen production was simulated and optimized using the coal gasification in the moving-bed reactor. In this reactor, coal from the top and the combination of oxidizing gas and steam from below is in contact with solid and gas produced comes out from the top of reactor. The results of the simulation have been compared with the experimental values and the average relative error of 2.47% indicated acceptable accuracy of simulation results. The effects of inlet gas temperature, reactor pressure, ratio of steam to oxygen and coal to oxygen are investigated on the hydrogen production efficiency. Although some studies have been published regarding the modeling of the moving-bed reactor in the coal gasification, limited parametric studies are available to investigate the effect of different variables on the reactor performance with Pittsburgh coal as food. Also, in this study, simulation with discrete temperature for gas and solid to determine the exact maximum temperature of the solid phase, the kinetics of all possible reactions, simultaneous use of shrinking core and volumetric models in different areas of reactor and considering the distribution of gas components in the pyrolysis stage, happened that it is useful to find out more precisely the composition of the product gas. Finally, the reactor performance for generating maximum hydrogen yield is optimized using the particle swarm optimization method. The optimization results show that there is a 24.3% increase in hydrogen production yield compared to the basic mode.

Moisture damage is one of the common causes of asphalt pavement failure in moisture presence. To reduce this damage, different additives such as lime, liquid anti stripping, etc. is conventionally added to mix. In this study, the effect of nano hydrated lime (Nano-HL), on the moisture susceptibility of asphalt mixtures was investigated by applying surface free energy principals, indirect tensile strength and resilient modulus tests. The asphalt specimens were prepared with granite aggregate and neat bitumen of 60/70 penetration grade containing 0%, 3% and 6% Nano-HL by bitumen weight. The results of this study indicate that modification of bitumen with Nano-HL decreases the acidic component of surface free energy and increases its basic components. So these changes improve the adhesion between the bitumen and aggregate. Also, cohesion free energy of bitumen is improved by an increase in a nonpolar component of bitumen. Furthermore, the results of the indirect tensile strength test and resilient modulus test indicate that the addition of Nano-HL in mixtures causes an increase in ITS and Mr values of modified HMA. On the other hand, the de-bonding energy of bitumen-aggregate for bitumen modified with this Nano material was decreased. This led to an increased resistance to moisture damage.