The model has been developed by considering two distinct zones in the downdraft gasifier: pyro-oxidation zone and reduction zone. The process in the pyro-oxidation zone has been solved based on the chemical equilibrium consideration considering water gas shift reaction and methanation reaction. The composition of different species (H2, CO, CO2, CH4, H2O, N2 and Char) and the temperature of the ...

The experimental study and modeling of gravity drainage during Water Alternative Gas Injection, WAG process, in carbonate rock for one of the Iranian off-shore reservoir at lab-scale were carried out. The mechanism of gravity drainage during the WAG process, and its contribution to the oil recovery in the fract...

  This paper presents a modeling study of a CNG Homogenous Charge Compression Ignition (HCCI) engine using single-zone and multi-zone combustion models. Authors' developed code could be able to predict engine combustion and performance parameters in closed part of the engine cycle. As detailed chemical kinetics is necessary to investigate combustion process in HCCI engines, therefore, GRI-m...

[1] We developed a multicomponent, multiphase, fluid and heat flow model to describe hydrate formation in marine sediments; the oneand two-dimensional model accounts for the dynamic effects of hydrate formation on salinity, temperature, pressure, and hydraulic properties. Free gas supplied from depth forms hydrate, depletes water, and elevates salinity until pore water is too saline for further...

The spatio-temporal variations of soil gas in the seismic fault zone produced by the 12 May 2008 Wenchuan Ms 8.0 earthquake were investigated based on the field measurements of soil gas concentrations after the main shock. Concentrations of He, H2, CO2, CH4, O2, N2, Rn, and Hg in soil gas were measured in the field at eight short profiles across the seismic rupture zone in June and December 200...

Methane hydrate (MH) is a new energy resource in the 21 century. But the dissociation of MH from sediments during the MH exploration or oil/gas exploration under a hydrate layer accompanied by the softening of soils and formation of excess pore gas pressure may lead to ground failures and environmental disasters. In this study, experiments on modeling the weakening and failure of the sediment b...

According to the present situations that the construction amount of the gas drainage boreholes in mining seam is large and the gas drainage effect in low permeability coal seams doesn’t yield perfect, the hydraulic reaming technology in mining seam is proposed to increase the gas drainage efficiency. Through the gas flow method, the effective influence radius of hydraulic reaming is determined....

A new method based on generalized reflection and transmission coefficients is proposed to calculate the synthetic seismograms in radially multilayered media. This method can be used to efficiently simulate full waveform acoustic logs and crosswell seismic profiles in situations where we need to consider borehole effects. The new formulation is tested by comparing our numerical results with prev...

A hybrid cordgrass, formed from a cross between Spartina alterniflora (Atlantic cordgrass) and S. foliosa (Pacific cordgrass), has recently spread within the intertidal zone of south San Francisco Bay. Sediment properties and macroinfaunal community structure were compared in patches invaded by Spartina hybrid and adjacent uninvaded patches at 3 sites in San Francisco Bay (2 tidal flats and 1 S...

The corrosion behavior of the fusion zone of gas tungsten arc (GTA) welds of AA6061 alloy was studied. Role of gas tungsten arc welding techniques such as continuous current (CC) and pulsed current (PC) and reference filler (AA5356) were studied. Role of different grain refiners such as scandium, zirconium and Tibor in the reference filler was studied. Dynamic polarization testing was used to d...