Study of combustion characteristics of macadamia shells and coffee husks briquettes in a fixed bed reactor

Abstract

Abstract In this paper the study was conducted to investigate the combustion characteristics of macadamia shells and coffee husks in a fixed bed reactor. The parameters tested included ignition time, flame propagation speed, mass loss history and temperature flame. Macadamia shell and coffee husk briquettes were produced by mixing with molasses in the ratio of 8:2 and compressed in a mold and piston press at a constant force of 100 K. The briquettes were tested in a fixed bed reactor operated at a constant air mass flowrate of 0.1 kg/s.. The study established that briquettes made from macadamia shells had a higher ignition time of 5.5 minutes compared to the coffee husk which had an ignition time of 2.5 minutes. In addition, briquettes made from macadamia have a lower flame propagation speed of 3.841×10-5 m/s compared to the flame propagation speed of coffee husks briquettes which was found to be 1.332×10-5 m/s. Macadamia briquettes resulted to higher flame temperatures of 600 oC compared to coffee husks briquettes 424 oC when burned in the fixed bed reactor. Therefore, Macadamia briquettes are suitable in small scale application as compared to coffee husk briquettes