123 research outputs found
Effect of Distributed Superficial-Velocity in Deep-Bed Grain Drying
This paper deals with influence of velocity field distribution to heat and mass transfer process in deep bed grain dryers. Two-dimensional (2D) models of deep-bed grain dryers were built by considering simultaneously momentum, heat, and mass transfer in the drying air phase. The Navier-Stokes momentum equations are applied to simulate pressure drop and velocity field of the drying airflow. Effect of velocity distribution to the heat and mass transfer coefficient distribution were simulated along the height of grains bed. The dynamic equations are solved numerically by using finite difference method by utilization of alternating direction implicit method, while the momentum equations are solved numerically by utilization of SIMPLE algorithm. The simulation results showed that velocity distribution along the grains bed - 5 cm of bed height - did not so influenced to the heat and mass transfer coefficient. Further, the vector plot of drying air superficial velocity field and contour of pressure distribution along deep bed of grain was simulated
Co-Generation of C2 Hydrocarbons and Synthesis Gases from Methane and Carbon Dioxide: a Thermodynamic Analysis
This paper deals with thermodynamic chemical equilibrium analysis using the method of
direct minimization of Gibbs free energy for all possible CH4 and CO2 reactions. The effects of CO2/CH4
feed ratio, reaction temperature, and system pressure on equilibrium composition, conversion, selectivity
and yield were studied. In addition, carbon and no carbon formation regions were also considered at
various reaction temperatures and CO2/CH4 feed ratios in the reaction system at equilibrium. It was
found that the reaction temperature above 1100 K and CO2/CH4 ratio=1 were favourable for synthesis
gas production with H2/CO ratio unity, while carbon dioxide oxidative coupling of methane (CO2 OCM)
reaction to produce ethane and ethylene is less favourable thermodynamically. Numerical results indicated
that the no carbon formation region was at temperatures above 1000 K and CO2/CH4 ratio larger than
Catalytic-Dielectric Barrier Discharge Plasma Reactor For Methane and Carbon Dioxide Conversion
A catalytic - DBD plasma reactor was designed and developed for co-generation of synthesis gas and C2+
hydrocarbons from methane. A hybrid Artificial Neural Network - Genetic Algorithm (ANN-GA) was developed
to model, simulate and optimize the reactor. Effects of CH4/CO2 feed ratio, total feed flow rate, discharge
voltage and reactor wall temperature on the performance of catalytic DBD plasma reactor was explored.
The Pareto optimal solutions and corresponding optimal operating parameters ranges based on
multi-objectives can be suggested for catalytic DBD plasma reactor owing to two cases, i.e. simultaneous
maximization of CH4 conversion and C2+ selectivity, and H2 selectivity and H2/CO ratio. It can be concluded
that the hybrid catalytic DBD plasma reactor is potential for co-generation of synthesis gas and higher hydrocarbons
from methane and carbon dioxide and showed better than the conventional fixed bed reactor
with respect to CH4 conversion, C2+ yield and H2 selectivity for CO2 OCM process
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