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The article addresses the implications of adopting (a) non-kinetic theory-based correlations for the estimation of thermodynamic and transport properties and (b) over-simplifying assumptions, as re...

Reactive systems in a thermochemical conversion domain are modelled considering N-specie, 1-energy and 2-mass conservation equations assuming negligible pressure gradient resulting in N+3 non-linear coupled PDE system with dependency on thermodynamic and transport properties. Typically, simplistic temperature-dependent polynomials are chosen for estimating thermal conductivity and specific heat, however, the estimation of mass diffusion coefficient (Di;mix) follows a complicated procedure involving kinetic theory culminating in Chapman-Enskog equation. This renders the solution computationally intensive. The complexity is simplified by assuming a constant Lewis (Le) number, a standard practice in the analytical solution for conventional reactive systems. In fixing Le, (Di;mix) is equated to thermal diffusivity (a ratio of thermodynamic properties) resulting in the specie and energy equation yielding a similar solution and collapse of N+3 system of simultaneous equations to 3 equations. The current article explores the validity and limitation of assuming constant Le in the simulation of char conversion process in air and steam. Results of char conversion are compared for fixed Le and D estimated with Chapman{Enskog expresion. The analysis suggests that Le remains invariant only under a severely restricted set of conditions. Fixing Le influences, the conversion process either over-/under-predicting the conversion time scales and the product gas composition.

A novel process for the manufacture of precipitated silica from rice husk ash, having a surface area ranging from $50-400m^2/g$ and tap density of $80-600kg/m^3$ having multiple applications in the field of rubbers and plastics, paints, toothpastes, catalyst, carrier agent, insulation, stabilizing and desiccants. The process method for silica precipitation is novel, where in the chemicals used are regenerated making it a closed loop operation. The extraction process through digestion, precipitation and regeneration are done based on the application specifies, so as to get the required particle size and densities.

This invention relates to a biomass gasifier for converting the solid biomass to gaseous fuel through thermo-chemical conversion using an open top down draft, dual air entry reactor. The gaseous fuel so generated is relatively free from undesirable ingredients like tar and particulates and can be used in an internal combustion engine for power generation. It is also used in thermal application where high quality heat is required.