Experimental analysis of fixed bed combustion of rice husk briquettes enriched with croton megalocarpus oil

Abstract

Rice husk briquettes are increasingly important as an alternative and renewable fuel. This study used biofuel-absorbed briquettes, a new method for using briquette fuels. In this way, the naturally existing briquette pores are filled with croton megalocarpus oil, improving the combustion properties compared to untreated (raw) briquettes. This study investigated combustion characteristics of rice husk briquettes enriched with croton megalocarpus oil (CMO). The briquettes were burnt in a fixed bed reactor. Air-mass fluxes were varied between 0.02 and 0.284 kg/m².s while croton megalocarpus oil absorption varied between 12% and 28% with both variations done at even increments. Key combustion parameters analyzed include peak flame temperature, burning rate, reaction zone thickness, flame propagation speed, and ignition time. The results demonstrate that croton megalocarpus oil absorption significantly influences combustion dynamics and briquette performance. It was established that the oil absorbed in the briquette had a positive impact in all the combustion properties. However, as oil absorption increases beyond the optimal level, the excess oil creates a dense layer around the briquettes that impedes oxygen diffusion which leads to fuel-rich conditions resulting in incomplete combustion. Consequently, beyond the optimal level of croton oil absorption, thermal performance of the briquettes was diminished.