3.8.1 Activation energy from single reaction model

The activation energies of five different biomasses, Low ash raw manure (LARM), low ash partially composted manure (LAPC), high ash raw manure (HARM), high ash partially composted manure (HAPC), and Texas Lignite coal (TXL), were determined by using the single reaction model. Tests were performed to see the variation of activation energy with changes in volatile matter (VM) of the fuel and mean particle diameter. Five fuel types were tested in a thermo gravimetric analyzer. Tests were conducted on three particle sizes: as received, 75 ^m, and 45 ^m. The activation energy for each of the fuels from the single reaction model is shown in Figure 3.17. The results indicate that the activation energy for low ash biomass is higher than that of high ash biomass for both raw and partially composted samples. In addition, the raw manure samples have slightly higher activation energies than the partially composted samples. It is noted that a uniform

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particle temperature assumption has been used. The size effect on pyrolysis values comes through the temperature gradient within the particle; however, the particle sizes here are extremely small. In addition, the heating rates are low; thus, the size effect may not be responsible for different activation energies.