Konovalov correlation for molar heats of combustion of organic compounds: its adoption for coal

Konovalovʹs correlation for molar heats of combustion of organic compounds has been suitably adopted for coal. Studies of a number of coal models, supported by experimental data on actual coals of varying rank, have revealed that ‘x’ the structure-related factor remains virtually constant at about 0.43 MJ kg−1 for all high volatile coals (C≤81%) beyond which it decreases almost linearly with increasing rank. A logical derivative of the correlation is also presented to give calorific values of coal on dry basis, from lignite to anthracite. Accuracy of the new correlation has been found to be as good as those of previous correlations, SD being about ±0.16, whereas its potential accuracy has been found to be as low as 0.05 MJ kg−1. Such high accuracy has not been hitherto reported for any other correlation. Significance of this vis-à-vis the values of ‘x’ and hence the structural pattern of coal is also discussed.