Combustion efficiency and CO/NO[formula omitted] emissions for a biomass plancha-type stove: Effect of the air excess ratio

Abstract

For plancha-type stoves, the chemical model of the combustion process and the influence of the air excess ratio (λ) have received little attention. The goal of this work is to use numerical simulations to study the influence of λ on the performance of a plancha-type stove. To simulate species transport, heat transfer, and fluid dynamics, the ANSYS FluentTM software is used. A two-reaction chemical model is employed to calculate volatile combustion efficiency (VCE), emissions of carbon dioxide (CO2), carbon monoxide (CO), and nitrogen oxides (NOX). Additionally, global parameters like thermal efficiency (TE) and heat transfer through the comal (Q) are evaluated. The following comparisons are offered to validate the numerical methodology: (i) to experimental measurements for the TUYA plancha type stove, (ii) to a one-reaction chemical model, and (iii) for various solid biofuels (fuelwood, charcoal, and peat). Results show that λ has a considerable impact on both VCE and CO2 emissions. VCE values were found to be up to 98% for λ=2.5 and λ=3. Lower combustion temperatures and higher values for λ increased NOX and CO emissions. Aside from the two-reaction model, the comparison to experimental performance is better when the air excess ratio and secondary-air were considered. Finally, with λ=3 and a temperature of injection of 1123 K, fuelwood has a higher VCE than charcoal and peat. Emissions and energy performance might vary dramatically for the different solid biofuels.