Three-dimensional non-linear numerical analysis on the oxygen concentration field in underground coal gasification

2004 ◽  
Vol 85 (15) ◽  
pp. 1605-1622 ◽  
Author(s):  
Lanhe Yang
Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2949 ◽  
Author(s):  
Hongtao Liu ◽  
Feng Chen ◽  
Yuanyuan Wang ◽  
Gang Liu ◽  
Hong Yao ◽  
...  

Underground coal gasification (UCG) produces less pollution and is safer than traditional coal mining. In order to investigate the effects of different gasifying agents or comprehensive analyses of the characteristics of the gas components in the three zones for the reverse underground coal gasification process, a model test was carried out. The results showed that the oxygen concentration of a gasifying agent is recommended to be higher than 21%, which will lead to more combustible gases and a higher calorific value of gas. Higher flow rates and oxygen content generally afforded more desirable gas compositions and calorific values, with the latter as high as 1430.19 kcal/Nm3. For the enriched oxygen gasifying agent in the reverse gasification process, the flow increase from 10 to 20 Nm3/h affords a rapid increase in the growth rate of the flame front, from 1.80 to 4.88 m/day, which is much faster than that for the air gasifying agent. Increasing the gas injection rate and oxygen concentration will increase the growth rate of the flame front. This affects the distribution of the three zones and further leads to different characteristics of the gas components.


2013 ◽  
Vol 688 ◽  
pp. 230-236
Author(s):  
Josip Galic ◽  
Tomislav Kisicek ◽  
Martina Galic

This paper describes the results of testing of unstrengthened and strengthened masonry walls subjected to horizontal in-plane load. Three kinds of specimens were tested: unstrengthened walls, walls strengthened with horizontal and walls strengthened with diagonal glass fiber straps. For unstrengthened walls and those strengthened with horizontal straps, a numerical simulation was performed. Software called MASA was used for this analysis. This software uses three dimensional non-linear numerical analysis of structure, made of quasi-brittle material, which is described with a microplane model. The results of numerical analysis very well described the behavior of unstrengthened and strengthened walls. In this paper, the application of such kind of strengthening, on rehabilitation of the existing masonry structure, Villa Kallina, in Zagreb, Croatia, was presented.


2000 ◽  
Author(s):  
Tien-Chien Jen ◽  
Gustavo Gutierrez ◽  
Sunil Eapen

Abstract A numerical analysis, using a control volume approach, is conducted to study the transient cutting tool temperatures with temperature dependent thermal properties. With temperature dependent thermal properties, the governing conduction equation is non-linear and thus, the standard analytical solutions are no longer valid. In any cutting processes, the temperature distribution is intrinsically three-dimensional and very steep temperature gradient may be generated in the vicinity of the tool-chip interface. In this region, where the maximum temperature occurs, the effect of variable thermal properties may become important. The full three-dimensional non-linear transient heat conduction equation is solved numerically to study these non-linear effects on cutting tool temperatures. The extremely small size of the heat input zone (tool-chip interface), relative to the tool insert rake surface area, requires the mesh to be dense enough in order to obtain accurate solutions. This usually requires very intensive computational efforts. Due to the size of the discretized domain, an efficient algorithm is desirable in the solution of the problem. Four different iterative schemes are explored, and an optimized numerical scheme is chosen to significantly reduce the required computing time. This numerical model can be used for process development in an industrial setting. The effect of two different heat flux input profiles, a spatially uniform plane heat flux and a spatially non-uniform plane heat flux at the tool-chip interface, on the tool temperatures are also investigated in the present study. Some recommendations are given regarding the condition when these non-linear effects can not be ignored.


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