Custard apple crop residues combustion: an overall study of their energy behaviour under different fertilisation conditions

Abstract

The current energy demand requires new energy sources. The use of biomass is an attractive option. In this work, the combustion thermal behaviour and kinetic of custard apple (Annona cherimola) crop remains derived from different plot fertilisation conditions (organic and inorganic) were studied. Thermogravimetry procedures were applied to seeds and wood under four heating rates (5, 10, 20 and 40 °C/min). Iso-conversional methods (Friedman, Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose) were used to determine the activation energy and the frequency factor. Fuel results showed a higher high heating value for seeds (~ 24.78 MJ/mol) when compared with wood (~ 19.33 MJ/mol). Thermogravimetric profiles denoted that, while seed samples were only affected by heating ramps, pruning remains were also influenced by the type of fertiliser. Organic fertiliser was responsible for higher maximum values on the second decomposition peak for wood samples, at 20 and 40 °C/min (56.78%/min and 23.03%/min). Kinetic indexes were also notably influenced by the fertiliser nature. Organic manure reduced the average activation energy results, being more perceptible in seeds (135.51–172.32 kJ/ mol) than wood (140.32–144.43 kJ/mol). Hence, it is proven that the type of fertilisation affects the thermal behaviour of custard apple residues