Is there a general relationship between the exergy and HHV for rice residues?

A relationship between exergy and HHV (higher heating value) for a fuel bridges a way for estimating the exergy of the fuel. The HHVs and exergy values of twenty eight rice husk samples and twenty four rice straw samples are investigated in this study to determine if there is a general relationship between exergy and HHV for rice residues. The results obtained from this study show that the HHVs of the rice husk samples are in the range of 9735.20–17285.00 kJ/kg whereas the exergy values are in the range of 10918.00–18458.00 kJ/kg. A specific relationship between exergy and HHV is observed for the rice husk samples, and the relative errors are −4.114%–2.621%. The HHVs of the rice straw samples are in the range of 10334.80–19942.90 kJ/kg whereas the exergy values are in the range of 11700.00–21506.00 kJ/kg. A specific relationship between exergy and HHV is observed for the rice straw samples, and the relative errors are −3.350%–2.027%. A general relationship between exergy and HHV is then observed for the rice residues, and the relative errors are −4.195%–2.623%. With these acceptable relative errors, the general relationship observed in this study can be used for expeditious calculation of the exergy of rice residues.