Thermoeconomics connects thermodynamics and economics, providing tools to solve problems in energy systems, both from the point of view of cost allocation, diagnosis and project optimization. A study of a gas turbine would take into account many characteristics: combustion process, change in the composition of the working fluid, irreversibility effects and so on. Considerable simplifications are often required, resulting in several thermodynamic models, which modify the results obtained in thermoeconomic optimization and in different thermoeconomic approaches for cost allocation. In the face of context, a study to verify the influence of thermodynamic models on the results obtained in thermoeconomic optimization and in the allocation of costs, it becomes promising and appreciable as it allows to analyze the difference in results, the reasonableness of simplifications and if it is worth using such a complex model. Thereby, this article compares four thermodynamic models in a cogeneration system: a standard air model, a standard cold air model, a CGAM model and a complete combustion model. The cogeneration system is optimized from the thermoeconomic point of view for each thermodynamic model. After the optimization process, five thermoeconomic approaches are used to allocate costs to the final products. The effects of these thermodynamic assumptions and the thermoeconomic approach on thermoeconomic optimization and cost allocation are presented and discussed. Of the computational effort to optimize the design problem, the complete combustion model is more efficient than the others models, since this model reaches an objective function value 5% lower than the CGAM problem. The analysis of the thermodynamic model variation for the same thermoeconomic method presents that the maximum variation of the unit cost values for useful heat and power is 4.3% and 5%, respectively. Similarly, the variation of the thermoeconomic model to the same thermodynamic model presents that the maximum variation of unit cost values for useful heat and power is 20% and 10%, respectively.

热经济学将热力学和经济学联系在一起，从成本分配，诊断和项目优化的角度出发，提供解决能源系统问题的工具。对燃气轮机的研究将考虑许多特征：燃烧过程，工作流体成分的变化，不可逆性影响等。通常需要进行大量简化，从而产生多个热力学模型，这些模型修改了在热经济优化和成本分配的不同热经济方法中获得的结果。面对这种情况，一项旨在验证热力学模型对热经济优化和成本分配中获得的结果的影响的研究由于能够分析结果差异而变得很有希望和可贵，简化的合理性，以及是否值得使用这种复杂模型。因此，本文比较了热电联产系统中的四个热力学模型：标准空气模型，标准冷空气模型，CGAM模型和完全燃烧模型。从热经济角度出发，针对每个热力学模型对热电联产系统进行了优化。在优化过程之后，使用了五种热经济方法将成本分配给最终产品。提出并讨论了这些热力学假设和热经济方法对热经济优化和成本分配的影响。在优化设计问题的计算工作中，完整的燃烧模型比其他模型更有效，因为该模型的目标函数值比CGAM问题低5％。对同一热经济方法的热力学模型变化的分析表明，有用热和功率的单位成本值的最大变化分别为4.3％和5％。类似地，热经济模型向同一热力学模型的变化表明，有用热能的单位成本值的最大变化分别为20％和10％。