A QSPR approach for accessing the lower heating value

Karsten Müller, Johannes Albert, Wolfgang Arlt Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany Institute of separation science and technology

The lower heating is an essential property for the evaluation of combustible fuels. Thermodynamically it can be seen as a heat of combustion corrected by the enthalpy of vaporisation of the water formed, which cannot be condensed in many practical energy applications. For many fuels these caloric data are available. However, no information about the heating value is available for many substances especially in the field of new tailor-made fuels based on renewable sources such as biomass. To reduce experimental effort it is desired to access this information based on fundamental structural information.
In this contribution we present a QSPR (quantitative structureâ??property relationship) model for the estimation of the lower heating value. Therein the molecular structure is divided into functional groups and a contribution to the lower heating value is assigned to each of these groups. Liquid fuel compounds and mixtures from biological as well as fossil or synthetic origin can be described using this approach.
High accuracy could be achieved using this model, not only for the reproduction of experimental data used for the parameter fitting, but also in an external validation based on compounds not used for the fitting. The absolute average error in this prediction was only 0.21 % for the reproduction of experimental data not used in the parameter fitting.
Based on the proposed method it is possible determine the energy contend of individual fuel components and based on that the value of potential new fuel mixtures.