Possible black universes in a brane world

A black universe is a nonsingular black hole where, beyond the horizon, there is an expanding, asymptotically isotropic universe. Such spherically symmetric configurations have been recently found as solutions to the Einstein equations with phantom scalar fields (with negative kinetic energy) as sources of gravity. They have a Schwarzschild-like causal structure but a de Sitter infinity instead of a singularity. It is attempted to obtain similar configurations without phantoms, in the framework of an RS2 type brane world scenario, considering the modified Einstein equations that describe gravity on the brane. By building an explicit example, it is shown that black-universe solutions can be obtained there in the presence of a scalar field with positive kinetic energy and a nonzero potential.Comment: 8 pages, 5 figures, gc styl

Tar formation influence on fixed bed air-blown biomass gasification process efficiency

The paper is devoted to reduced biomass gasification tar formation model. According to this model, fixed volatiles part escapes fuel in the form of tars. Tar content influence on the cold gas efficiency is analyzed. It is shown that tar formation in is key process that determines gasification process efficiency

MATHEMATICAL MODELLING OF WOOD GASIFICATION WITH TARRY PRODUCTS DECOMPOSITION ON ACTIVE MATERIAL PARTICLES

The work is devoted to the numerical study of the process of downdraft fixed-bed gasification of woody biomass. Such processes are used to produce combustible gases at lowcapacity power plants. To improve the quality of the produced gas, it is proposed to use a mixture of wood fuel with a non-combustible material that can exhibit catalytic activity in the decomposition of undesired tary products. Adding a non-combustible material leads to lower heat value of fuel mixture, but contributes to a deeper gas purification. The aim of the study is to select the optimal "active material / wood fuel" ratio and to determine the minimum material activity at which its addition to the fuel becomes effective