Neto Abel F G, Huda Muhammad N, Marques Francisco C, Borges Rosivaldo S, Neto Antonio M J C
Laboratory of Preparation and Computation of Nanomaterials (LPCN), Federal University of Pará, C.P. 479, Belém, PA, 66075-110, Brazil.
Post-graduation Program of Natural Resources Engineering of Amazon - PRODERNA; ITEC, State University of Pará, 2626, Belém, PA, 66.050-540, Brazil.
J Mol Model. 2017 Aug;23(8):224. doi: 10.1007/s00894-017-3401-1. Epub 2017 Jul 14.
Density functional theory was performed for thermodynamic predictions on natural gas, whose B3LYP/6-311++G(d,p), B3LYP/6-31+G(d), CBS-QB3, G3, and G4 methods were applied. Additionally, we carried out thermodynamic predictions using G3/G4 averaged. The calculations were performed for each major component of seven kinds of natural gas and to their respective air + natural gas mixtures at a thermal equilibrium between room temperature and the initial temperature of a combustion chamber during the injection stage. The following thermodynamic properties were obtained: internal energy, enthalpy, Gibbs free energy and entropy, which enabled us to investigate the thermal resistance of fuels. Also, we estimated an important parameter, namely, the specific heat ratio of each natural gas; this allowed us to compare the results with the empirical functions of these parameters, where the B3LYP/6-311++G(d,p) and G3/G4 methods showed better agreements. In addition, relevant information on the thermal and mechanic resistance of natural gases were investigated, as well as the standard thermodynamic properties for the combustion of natural gas. Thus, we show that density functional theory can be useful for predicting the thermodynamic properties of natural gas, enabling the production of more efficient compositions for the investigated fuels. Graphical abstract Investigation of the thermodynamic properties of natural gas through the canonical ensemble model and the density functional theory.
采用密度泛函理论对天然气进行热力学预测,应用了B3LYP/6 - 311++G(d,p)、B3LYP/6 - 31+G(d)、CBS - QB3、G3和G4方法。此外,我们还使用G3/G4平均值进行了热力学预测。对七种天然气的每种主要成分及其各自的空气 + 天然气混合物在室温与喷射阶段燃烧室初始温度之间的热平衡状态下进行了计算。获得了以下热力学性质:内能、焓、吉布斯自由能和熵,这使我们能够研究燃料的热阻。此外,我们还估算了一个重要参数,即每种天然气的比热比;这使我们能够将结果与这些参数的经验函数进行比较,其中B3LYP/6 - 311++G(d,p)和G3/G4方法显示出更好的一致性。此外,还研究了天然气热阻和机械阻力的相关信息以及天然气燃烧的标准热力学性质。因此,我们表明密度泛函理论可用于预测天然气的热力学性质,从而为所研究的燃料生产更高效的成分。图形摘要 通过正则系综模型和密度泛函理论对天然气热力学性质的研究。